JP6013745B2 - Ground improvement method - Google Patents

Description

  The present invention relates to a ground improvement method for stabilizing a structure by improving the ground directly under a structure such as a road embankment, a retaining wall, or a lifeline pipe buried in the ground to prevent liquefaction.

  Conventionally, ground improvement has been carried out by solidification treatment not only for the overload of a structure but also for the purpose of preventing liquefaction of the ground. Although it is necessary to increase the strength of the ground due to the solidification treatment for the load on the structure, it is not necessary to increase the strength of the ground due to the solidification treatment in order to prevent liquefaction of the ground.

JP 2000-212949 A JP 2007-297839 A

  However, in order to prevent liquefaction of the ground, if the amount of the solidifying material added is reduced, the strength of the solidified ground will vary, which is unavoidable.

  Therefore, the present invention has been made to solve the above-described problems, and a ground improvement method capable of reducing the cost without increasing the ground strength more than necessary to prevent liquefaction. The purpose is to provide.

According to the first aspect of the present invention, when the ground directly under the structure is improved, the ground immediately below the structure is stabilized by solidification treatment with respect to the overload of the structure, and the liquefaction during an earthquake is It is a ground improvement method that stabilizes the structure by desaturating the ground area by injecting air into the ground area necessary to ensure the stability of the structure, where liquefaction sometimes occurs. Then, improve the ground by a solidification process with a plurality of columnar piles in the ground immediately below the structure by a solidification process with a plurality of columnar piles , and then a solidification process with the plurality of columnar piles The unsaturated region is formed by injecting the air below the groundwater level in the region between the plurality of columnar piles improved by ground.

  The invention of claim 2 is the ground improvement method according to claim 1, wherein when the air is injected, a borehole is formed from the ground, and then an air injection tube is inserted into the borehole. The air is injected from an injection hole of an air injection tube.

Invention of Claim 3 is the ground improvement method of Claim 1, Comprising: The said air is carried out below the said groundwater level of the passive earth pressure area | region of the circumference | surroundings of the area | region required stably with respect to the mounting load of the said structure. A region that is unsaturated by implantation is further formed.

  According to the present invention, it is necessary to stabilize the structure by increasing the strength of the ground for the load on the structure, and to stabilize the structure by desaturating the ground for liquefaction of the ground. The cost can be reduced without increasing the strength of the ground.

That is, by combining the desaturation process by injection of groundwater level below the air in the region between the plurality of columnar Pile soil improvement methods and ground improvement by solidification of a plurality of columnar pile, a range of ground improvement The cost can be reduced as much as possible, the cost can be further reduced, and the effects of both methods can be superimposed to prevent liquefaction during an earthquake more effectively. .

(A) is explanatory drawing before construction of the ground improvement method of 1st Embodiment of this invention, (b) is explanatory drawing in the middle of construction of the method. It is explanatory drawing after construction of the ground improvement method of the said 1st Embodiment. (A) is explanatory drawing before construction of the ground improvement method of 2nd Embodiment of this invention, (b) is explanatory drawing in the middle of construction of the method. It is explanatory drawing after construction of the ground improvement method of the said 2nd Embodiment. (A) is explanatory drawing before construction of the ground improvement method of 3rd Embodiment of this invention, (b) is explanatory drawing in the middle of construction of the method, (c) is explanatory drawing after construction of the method. (A) is explanatory drawing before construction of the ground improvement method of 4th Embodiment of this invention, (b) is explanatory drawing in the middle of construction of the method. It is explanatory drawing after construction of the ground improvement method of the said 4th Embodiment. (A) is explanatory drawing before construction of the ground improvement method of 5th Embodiment of this invention, (b) is explanatory drawing in the middle of construction of the method. It is explanatory drawing after construction of the ground improvement method of the said 5th Embodiment. (A) is explanatory drawing before construction of the ground improvement method of 6th Embodiment of this invention, (b) is explanatory drawing in the middle of construction of the method. It is explanatory drawing after construction of the ground improvement method of the said 6th Embodiment. It is explanatory drawing in the middle of construction of the modification of the ground improvement method of the said 6th Embodiment. It is explanatory drawing in the middle of construction of the ground improvement method of 7th Embodiment of this invention. It is explanatory drawing in the middle of construction of the ground improvement method of 8th Embodiment of this invention.

  In the ground improvement method of the present invention, the whole surface improvement method and the partial improvement method can be adopted as a solidification treatment method for stabilizing the structure by increasing the strength of the ground due to the solidification treatment with respect to the overload of the structure. In the improved form, a method of arranging the columnar solidified piles at appropriate intervals, a method of bundling the columnar solidified piles and arranging them in a block form, or a lattice-like improvement is adopted as a modification of the block-like improved form.

  In order to ensure the stability of the ground where liquefaction occurs during an earthquake for each improved type, air is injected into the improved earth pressure region (front surface), main earth pressure region (rear surface), and the lower part of the improved portion to desaturate. To prevent liquefaction. Moreover, in the liquefaction countermeasure in the column-shaped solidified pile and the grid-like improved form, it is desaturated by injecting air into the improved area.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the embodiments, air is injected after the structure is constructed by performing ground improvement by solidification processing in advance, but air may be injected before the structure is constructed.

<First Embodiment>
1A is an explanatory diagram before construction of the ground improvement method according to the first embodiment of the present invention, FIG. 1B is an explanatory diagram during construction of the method, and FIG. 2 is an explanatory diagram after construction of the method. It is.

  In the ground improvement method according to the first embodiment, first, the area 2 that is stably required for the load on the road embankment (structure) 10 is improved by the solidification treatment of the solidified pile 8, and then liquid in the event of an earthquake. The region 2 of the ground 1 is desaturated by injecting the air A into the region 2 of the ground 1 necessary to ensure the stability of the road embankment 10 in the ground 1 where the slagging occurs. As a result, the road embankment 10 is stabilized by increasing the strength of the ground 1 with respect to the loading load of the road embankment 10, and the road embankment 10 with the ground 1 being desaturated with respect to the liquefaction of the ground 1. This is a method capable of reducing the cost without increasing the strength of the ground 1 more than necessary, and will be described in detail below with reference to FIGS. 1 (a), 1 (b) and FIG.

First, as shown in FIG. 1 (a), a predetermined number of columnar solidified piles (columnar piles) 8 are arranged in the ground 1 such as sand ground directly below the road embankment 10, and the road embankment 10 Immediately solidify and improve the ground 1 directly under the solidified pile 8. In this case, the solidified pile 8 is constructed to a depth at which stability can be ensured with respect to the road embankment 10. A region to be solidified and improved by the solidified pile 8 is denoted by reference numeral 2 in FIG.

  Next, as shown in FIG. 1 (b), a boring hole 6 is excavated in the vertical direction from the road embankment 10 in the region 2 to be solidified and improved by the plurality of columnar solidified piles 8. In this case, a plurality of boring holes 6 are formed at intervals at which air A can be reliably injected into the ground 1. The drilling direction of the boring hole 6 is not limited to the vertical direction, and the boring hole 6 may be drilled obliquely downward in the region 2 to be solidified and improved from the ground 1a or the road embankment 10 on both sides of the road embankment 10. good.

Next, the air injection tube 7 is inserted to the lower end of the boring hole 6. Then, as shown in FIG. 1 (b), by injecting air injection tubes 7 or al air A, plurality of solidified improved by a plurality of columnar solidification pile 8 of cylindrical between solidification pile 8 Air A is injected into the region 2 to form an unsaturated region 2 'below the groundwater level 101 as shown in FIG.

  The injection of the air A into the region 2 to be solidified and improved by the solidified pile 8 is performed after the air injection pipe 7 is inserted to the lower end of the boring hole 6, but the air injection pipe 7 is lowered to the lower end of the boring hole 6. You may perform in the middle or in the middle of pulling up the air injection pipe 7 from the lower end of the boring hole 6. The air injection tube 7 used here has, for example, a large number of fine through holes as injection holes for injecting air at the tip.

  In this way, by forming the unsaturated region 2 'below the groundwater level 101 in the region 2 to be solidified and improved by the solidified pile 8 of the ground 1 directly below the road embankment 10, the region immediately below the road embankment 10 during an earthquake. The liquefaction of the ground 1 can be reliably prevented. In this case, a boring hole 6 is excavated in a vertical direction from the road embankment 10 in the region 2 to be solidified and improved by the solidified pile 8, and an air injection pipe 7 is inserted into the bore hole 6. Since it is a simple method of simply injecting air A, it can be constructed with low cost by a small machine, and measures for liquefaction in the area 2 to be solidified and improved by the solidified pile 8 of the ground 1 directly under the road embankment 10 It can be performed easily and reliably at low cost. As a result, it is possible to reliably prevent liquefaction of the ground 1 immediately below the road embankment 10 at the time of an earthquake and increase the bearing capacity of the road embankment 10 in an economical construction. The sinking and inclination of the road embankment 10 can be reliably prevented, and the stability of the road embankment 10 can be sufficiently ensured.

  Furthermore, since the boring hole 6 is excavated in the vertical direction from the ground surface of the road embankment 10, the construction is simple and the construction cost can be suppressed. Further, when the boring hole 6 cannot be excavated from the ground surface of the road embankment 10, the road embankment 10 is avoided and the boring toward the region 2 solidified and improved by the solidified pile 8 from the ground 1a of the ground 1 is performed. A hole is excavated obliquely downward, an air injection pipe 7 is inserted into the drilled borehole, and air A is injected from the tip of the air injection pipe 7 into the region 2 to be solidified and improved by the solidified pile 8. Thus, the unsaturated region 2 'may be formed. In this case, since the boring hole is excavated obliquely downward from the ground 1a of the ground 1, the construction is easy, the construction cost can be reduced, and the ground 1 directly below the road embankment 10 can be easily and reliably removed. Can be saturated.

Second Embodiment
FIG. 3 (a) is an explanatory diagram before construction of the ground improvement method of the second embodiment of the present invention, FIG. 3 (b) is an explanatory diagram during construction of the method, and FIG. 4 is an explanatory diagram after construction of the method. It is.

  In the ground improvement method according to the second embodiment, first, the area 2 that is stably required for the load on the road embankment (structure) 10 is improved by solidifying the solidified pile 8, and then the liquid is restored during an earthquake. By injecting air A into the areas 2 and 3 of the ground 1 necessary to ensure the stability of the road embankment 10 in the ground 1 where the slagging occurs, the areas 2 and 3 of the ground 1 are desaturated. As a result, the road embankment 10 is stabilized by increasing the strength of the ground 1 with respect to the loading load of the road embankment 10, and the road embankment 10 with the ground 1 being desaturated with respect to the liquefaction of the ground 1. This is a method that can reduce the cost without increasing the strength of the ground 1 more than necessary, and will be described in detail below with reference to FIGS.

  First, as shown in FIG. 3 (a), a predetermined number of columnar solidified piles 8 are arranged in the ground 1 such as sand ground directly under the road embankment 10, and the ground 1 directly under the road embankment 10 is disposed. Solidification is improved with the solidified pile 8. In this case, the solidified pile 8 is constructed to a depth at which stability can be ensured with respect to the road embankment 10. A region to be solidified and improved by the solidified pile 8 is denoted by reference numeral 2 in FIG. 3, a surrounding passive earth pressure region is denoted by reference numeral R in FIG. 3, and a passive earth pressure collapse angle is denoted by reference numeral α in FIG. Here, the passive earth pressure region R is a region of the ground that is pressed when the region 2 is subjected to horizontal force due to the horizontal acceleration of the earthquake and the region 2 tries to move horizontally during the earthquake. The earth pressure collapse angle α refers to an angle at which the ground 1 collapses in the passive earth pressure region R, and both the passive earth pressure region R and the passive earth pressure collapse angle α are obtained by a known calculation method.

  Next, as shown in FIG. 3 (b), liquefaction occurs at the time of the earthquake in the region 2 to be solidified and improved by the plurality of columnar solidified piles 8 and the passive earth pressure region R around the region 2 to be solidified and improved by the solidified piles 8. The borehole 6 is excavated in the vertical direction on the road embankment 10 and on the ground 1a in the region 3 in which it is expected. In this case, a plurality of boring holes 6 are formed at intervals at which air A can be reliably injected into the ground 1. The direction in which the boring hole 6 is excavated is not limited to the vertical direction, but the region 2 that solidifies and improves on the road embankment 10 of the ground 1 or the ground 1a and the passive earth pressure region R are regions where liquefaction is expected during an earthquake. 3 may be excavated with the bore hole 6 obliquely downward.

Next, the air injection tube 7 is inserted to the lower end of the boring hole 6. Then, as shown in FIG. 3 (b), by injecting air injection tubes 7 or al air A, plurality of solidified improved by a plurality of columnar solidification pile 8 of cylindrical between solidification pile 8 Air A is injected into the region 3 where the liquefaction is expected in the region 2 and the passive earth pressure region R, and as shown in FIG. 4, the unsaturated regions 2 'and 3' are below the groundwater level 101 or lower. To form.

  Injecting the air A into the region 2 to be solidified and improved by the solidified pile 8 and the region 3 in the passive earth pressure region R where liquefaction is expected at the time of an earthquake, insert the air injection pipe 7 to the lower end of the boring hole 6. However, the air injection tube 7 may be lowered to the lower end of the boring hole 6 or may be performed while the air injection tube 7 is pulled up from the lower end of the boring hole 6. The air injection tube 7 used here has, for example, a large number of fine through holes as injection holes for injecting air at the tip.

  As described above, the regions 2 ′ and 3 that are desaturated into the region 2 that is solidified and improved by the solidified pile 8 of the ground 1 immediately below the road embankment 10 and the region 3 that is expected to be liquefied during an earthquake in the passive earth pressure region R. By forming ′ below the groundwater level 101 or less, liquefaction of the ground 1 immediately below the road embankment 10 can be reliably prevented during an earthquake. In this case, a drilling hole 6 is excavated on the road embankment 10 and in the vertical direction from the ground 1a in the region 2 where solidification is improved by the solidified pile 8 and the region 3 where liquefaction is expected in the passive earth pressure region R. Since the air injection pipe 7 is inserted into the boring hole 6 and the air A is simply injected from the air injection pipe 7, it can be constructed with a small machine at low construction cost. It is possible to easily and reliably carry out liquefaction countermeasures in the region 2 where solidification is improved by the solidified pile 8 of the ground 1 immediately below and the region 3 where the liquefaction is expected in the passive earth pressure region R during an earthquake. As a result, it is possible to reliably prevent liquefaction of the ground 1 immediately below the road embankment 10 at the time of an earthquake and increase the bearing capacity of the road embankment 10 in an economical construction. The sinking and inclination of the road embankment 10 can be reliably prevented, and the stability of the road embankment 10 can be sufficiently ensured.

  Furthermore, since the boring hole 6 is excavated in the vertical direction from the ground surface of the road embankment 10 and the ground 1a of the ground 1, the construction is simple and the construction cost can be suppressed. Further, when the borehole 6 cannot be excavated from the ground surface of the road embankment 10, the area 2 to be solidified and improved by the solidified pile 8 from the ground 1a of the ground 1 and the passive earth pressure are avoided. In the region R, a boring hole is drilled obliquely downward toward the region 3 where liquefaction is expected at the time of an earthquake, and an air injection pipe 7 is inserted into the drilled bore hole. By injecting A into the region 2 where solidification is improved by the solidified pile 8 and the region 3 where the liquefaction is expected in the passive earth pressure region R, the unsaturated regions 2 'and 3' are below the groundwater level 101 or lower. You may make it form in. In this case, since the boring hole is excavated obliquely downward from the ground 1a of the ground 1, the construction is easy, the construction cost can be suppressed, and the ground 1 directly below the road embankment 10 can be easily and reliably constructed. Can be unsaturated.

  Further, the area 3 where the liquefaction is expected in the passive earth pressure area R around the area 2 to be solidified and improved by the solidified pile 8 of the ground 1 immediately below the road embankment 10 is the boundary of the site of the road embankment 10 Even when it is outside, by excavating the boring hole 6 diagonally downward from the ground 1a in the boundary of the road embankment 10 site, the passive earth pressure region R applied outside the site boundary of the road embankment 10 The air A can be easily and reliably injected into the region 3 where liquefaction is expected during an earthquake through the air injection pipe 7 and can be desaturated. In other words, the desaturation method for injecting air A into the ground 1 can be improved while still in the original ground state, and since it is air A that exists in nature, there is no harm and boring from within the site area. By excavating the hole diagonally, air A can be injected into the passive earth pressure region R, and it is not necessary to provide a construction yard etc. outside the site area. Can do.

<Third Embodiment>
FIG. 5A is an explanatory diagram before construction of the ground improvement method of the third embodiment of the present invention, FIG. 5B is an explanatory diagram during construction of the method, and FIG. 5C is after construction of the method. It is explanatory drawing of.

  In the ground improvement method of the third embodiment, first, the area 2A that is stably required for the load on the road embankment (structure) 10 is improved to a block shape by solidification processing such as deep mixing processing, and then The region 3 of the ground 1 is desaturated by injecting air A into the region 3 of the ground 1 necessary to ensure the stability of the road embankment 10 in the ground 1 where liquefaction occurs during an earthquake. As a result, the road embankment 10 is stabilized by increasing the strength of the ground 1 with respect to the loading load of the road embankment 10, and the road embankment 10 with the ground 1 being desaturated with respect to the liquefaction of the ground 1. Therefore, the cost can be reduced without increasing the strength of the ground 1 more than necessary, and will be described in detail with reference to FIGS. 5 (a), 5 (b), and 5 (c).

  First, as shown in FIG. 5A, the ground 1 such as sand ground directly on both sides of the road embankment 10 is solidified and improved in a block shape by a method such as deep mixing treatment. The area to be solidified and improved on both sides immediately below the road embankment 10 is indicated by reference numeral 2A in FIG. 5, the surrounding earth pressure area is indicated by numeral R in FIG. 5, and the earth pressure collapse angle is indicated by the numeral in FIG. Indicated by α.

  Next, as shown in FIG. 5 (b), liquefaction is expected during an earthquake in the passive earth pressure regions R and R around the regions 2A and 2A where the ground 1 on both sides just below the road embankment 10 is solidified and improved. Boring holes 6 are excavated in the vertical direction from the ground 1a in the regions 3 and 3 to be drilled. In this case, a plurality of boring holes 6 are formed at intervals at which air A can be reliably injected into the ground 1. The excavation direction of the bore link hole 6 is not limited to the vertical direction, and drilling from the ground surface 1a of the ground 1 or the ground surface side of the road embankment 10 to the region 3 where liquefaction is expected at the time of an earthquake in the passive earth pressure region R. You may excavate the hole 6 toward diagonally downward.

  Next, the air injection tube 7 is inserted to the lower end of the boring hole 6. Then, as shown in FIG. 5B, by injecting air A from the air injection pipe 7 into the region 3 where liquefaction is expected in the passive earth pressure region R in the passive earth pressure region R, Air A is injected into the region 3 where liquefaction is expected to form an unsaturated region 3 ′ below the groundwater level 101 as shown in FIG.

  In the passive earth pressure region R, the injection of the air A into the region 3 where liquefaction is expected at the time of an earthquake is performed after inserting the air injection tube 7 to the lower end of the boring hole 6, but to the lower end of the boring hole 6. You may perform in the middle of lowering the air injection pipe 7, or in the middle of raising the air injection pipe 7 from the lower end of the boring hole 6. The air injection tube 7 used here has, for example, a large number of fine through holes as injection holes for injecting air at the tip.

  In this manner, the areas 2A and 2A around the ground 1 immediately below the road embankment 10 where the solidification is improved, the passive earth pressure areas R and R around the areas 1 and 3 are desaturated in the areas 3 and 3 where liquefaction is expected during an earthquake. By forming the regions 3 'and 3' below the groundwater level 101 or less, liquefaction of the ground 1 immediately below and around the road embankment 10 can be reliably prevented during an earthquake. In this case, the bored hole 6 is excavated in the vertical direction from the ground 1a of the ground 1 to the regions 3 and 3 where liquefaction is expected in the passive earth pressure regions R and R around the regions 2A and 2A to be solidified. Since the air injection pipe 7 is inserted into the borehole 6 and the air A is simply injected from the air injection pipe 7, it can be constructed with a small machine at a low construction cost. The countermeasure for liquefaction around the area 2A where the solidification improvement of the ground 1 immediately below 10 is improved can be performed easily and reliably at low cost. As a result, it is possible to reliably prevent liquefaction during an earthquake and enhance the bearing capacity of the road embankment 10 in economical construction, and due to liquefaction directly below and around the road embankment 10 during an earthquake. The sinking and inclination of the road embankment 10 can be reliably prevented, and the stability of the road embankment 10 can be sufficiently ensured.

  Further, the areas 3 and 3 where the liquefaction is expected in the passive earth pressure areas R and R around the areas 2A and 2A around the ground 1 on both sides immediately below the road embankment 10 are expected to be liquefied. Even when it is outside the boundary of the site of the bank embankment 10, by drilling the boring hole 6 diagonally downward from the ground 1a in the boundary of the site of the road embankment 10 outside the boundary of the site of the road embankment 10 In the passive earth pressure region R, the air A can be easily and reliably injected into the region 3 where liquefaction is expected during an earthquake through the air injection pipe 7 and can be desaturated. In other words, the desaturation method for injecting air A into the ground 1 can be improved while still in the original ground state, and since it is air A that exists in nature, there is no harm and boring from within the site area. By drilling the hole 6 diagonally, air A can be injected into the passive earth pressure region R, and there is no need to provide a construction yard or the like outside the site area, so construction is easy and reliable at a low cost in a gentle construction environment. be able to.

  Further, as shown in FIG. 5C, when the main earth pressure area 2B between the areas 2A and 2A of the ground 1 on both sides immediately below the road embankment 10 is liquefied by an earthquake, the main earth pressure is reduced. Since the area 2A that has been solidified and improved becomes unstable, the main earth pressure area 2B is also liquefied. By injecting air A into this area and desaturating it, the road embankment 10 in the event of an earthquake is obtained. Liquefaction of the entire region directly below and the surrounding ground 1 can be reliably prevented.

<Fourth embodiment>
6A is an explanatory diagram before construction of the ground improvement method of the fourth embodiment of the present invention, FIG. 6B is an explanatory diagram during construction of the method, and FIG. 7 is an explanatory diagram after construction of the method. It is.

  In the ground improvement method of the fourth embodiment, first, the region 2 that is stably required for the loading load of the retaining wall (structure) 11 is improved by solidifying the solidified pile 8, and then liquefied during an earthquake. The region 2 of the ground 1 is desaturated by injecting air A into the region 2 of the ground 1 necessary to ensure the stability of the retaining wall 11 in the ground 1 where the ground is generated. Accordingly, the retaining wall 11 is stabilized by increasing the strength of the ground 1 with respect to the loading load of the retaining wall 11, and the retaining wall 11 is stabilized with desaturation of the ground 1 against liquefaction of the ground 1. Therefore, this is a method capable of reducing the cost without increasing the strength of the ground 1 more than necessary, and will be described in detail with reference to FIGS. 6 (a), 6 (b) and FIG.

  First, as shown in FIG. 6A, a predetermined number of columnar solidified piles 8 are disposed in the ground 1 such as sand ground directly below the foundation 11a of the retaining wall 11 made of reinforced concrete, and the foundation of the retaining wall 11 is formed. The ground 1 immediately below 11 a is solidified and improved by the solidified pile 8. In this case, the solidified pile 8 is constructed to a depth at which stability can be ensured with respect to the foundation 11 a of the retaining wall 11. A region to be solidified and improved by the solidified pile 8 is denoted by reference numeral 2 in FIG.

  Next, as shown in FIG. 6 (b), a boring hole 6 ′ is excavated obliquely downward from the ground 1 a of the ground 1 directly below the region 2 to be solidified and improved by a plurality of columnar solidified piles 8. In this case, a plurality of boring holes 6 ′ are formed while maintaining an interval and an oblique angle at which air A can be reliably injected into the ground 1.

  Next, the air injection pipe 7 is inserted to the lower end of the bored hole 6 'excavated obliquely downward. Then, as shown in FIG. 6 (b), air A is injected into the region 2 to be solidified and improved by the solidified pile 8 by injecting air A from the air injection pipe 7 to the region 2 to be solidified and improved by the solidified pile 8. Then, as shown in FIG. 7, the unsaturated region 2 ′ is formed below the groundwater level 101.

  The injection of the air A into the region 2 to be solidified and improved by the solidified pile 8 is performed after inserting the air injection pipe 7 to the lower end of the borehole 6 'excavated obliquely downward. You may perform in the middle of inserting the air injection pipe 7 to a lower end, or in the middle of raising the air injection pipe 7 from the lower end of the boring hole 6 '. The air injection tube 7 used here has, for example, a large number of fine through holes as injection holes for injecting air at the tip, but a large number of fine through holes for air injection are provided from the tip to the middle part. It may be good.

  In this way, by forming the unsaturated region 2 ′ below the groundwater level 101 in the region 2 to be solidified and improved by the solidified pile 8 of the ground 1 directly below the foundation 11a of the retaining wall 11, Liquefaction of the ground 1 directly below the foundation 11a can be reliably prevented. In this case, a boring hole 6 ′ is excavated obliquely downward from the ground 1 a in the site where the retaining wall 11 is provided in the region 2 to be solidified and improved by the solidified pile 8, and the air injection pipe 7 is inserted into the boring hole 6 ′. This is a simple method of injecting air A from the air injection pipe 7, so that it can be constructed with low cost by a small machine, and the ground 1 immediately below the foundation 11 a of the retaining wall 11 is solidified. The measures for liquefaction of the region 2 to be solidified and improved by the pile 8 can be easily and reliably performed at low cost. Thereby, it is possible to increase the bearing capacity of the retaining wall 11 by reliably preventing the liquefaction of the ground 1 immediately below the foundation 11a of the retaining wall 11 at the time of an earthquake by economical construction. The retaining wall 11 can be reliably prevented from sinking or tilting, and the retaining wall 11 can be sufficiently stable.

  Further, avoiding the foundation 11a of the retaining wall 11, the boring hole 6 'is excavated from the ground 1a of the ground 1 diagonally downward to the region 2 where the solidified pile 8 solidifies and improved, and the oblique boring hole 6'. Since the air injection pipe 7 is inserted into the area 2 where the air A is solidified and improved by the solidified pile 8 from the tip of the air injection pipe 7, the ground 1 immediately below the foundation 11 a of the existing retaining wall 11 is inserted. This can be easily applied when the region 2 to be solidified and improved by the solidified pile 8 is made unsaturated. That is, the construction is simple, the construction cost can be suppressed, and the ground 1 immediately below the foundation 11a of the retaining wall 11 can be easily and reliably unsaturated.

  Further, even when the installation position of the boring hole 6 'excavated obliquely downward from the ground 1a is limited, it can be easily handled by changing the excavating angle of the boring hole 6'.

<Fifth Embodiment>
8A is an explanatory diagram before construction of the ground improvement method of the fifth embodiment of the present invention, FIG. 8B is an explanatory diagram during construction of the method, and FIG. 9 is an explanatory diagram after construction of the method. It is.

  In the ground improvement method of the fifth embodiment, first, the region 2 that is stably required for the loading load of the retaining wall (structure) 11 is improved by solidifying the solidified pile 8, and then liquefied during an earthquake. The region 2 and 3 of the ground 1 is desaturated by injecting the air A into the regions 2 and 3 of the ground 1 necessary for ensuring the stability of the retaining wall 11 in the ground 1 where the ground is generated. Accordingly, the retaining wall 11 is stabilized by increasing the strength of the ground 1 with respect to the loading load of the retaining wall 11, and the retaining wall 11 is stabilized with desaturation of the ground 1 against liquefaction of the ground 1. Therefore, this is a method capable of reducing the cost without increasing the strength of the ground 1 more than necessary, and will be described in detail with reference to FIGS. 8 (a), 8 (b) and FIG.

  First, as shown in FIG. 8 (a), a predetermined number of columnar solidified piles 8 are arranged in the ground 1 such as sand ground directly under the foundation 11a of the reinforced concrete retaining wall 11, and the foundation of the retaining wall 11 is arranged. The ground 1 immediately below 11 a is solidified and improved by the solidified pile 8. In this case, the solidified pile 8 is constructed to a depth at which stability can be ensured with respect to the foundation 11 a of the retaining wall 11. The region to be solidified and improved by the solidified pile 8 is indicated by reference numeral 2 in FIG. 8, the surrounding passive earth pressure region is indicated by reference numeral R in FIG. 8, and the passive earth pressure collapse angle is indicated by reference numeral α in FIG.

  Next, as shown in FIG. 8 (b), liquefaction occurs in an earthquake in the region 2 to be solidified and improved by a plurality of columnar solidified piles 8 and the passive earth pressure region R around the region 2 to be solidified and improved by solidified piles 8. Is drilled in the vertical direction and obliquely downward from the ground 1a of the ground 1 below the region 3 where the ground is expected. In this case, a plurality of boring holes 6, 6 ′ are formed while maintaining an interval and an oblique angle at which air A can be reliably injected into the ground 1.

  Next, the air injection pipe 7 is inserted to the lower end of the bored holes 6 and 6 'excavated vertically and obliquely downward. Then, as shown in FIG. 8 (b), air A is injected from the air injection pipe 7 into the region 2 where solidification is improved by the solidified pile 8 and the region 3 where liquefaction is expected at the time of the earthquake in the passive earth pressure region R. By injecting air A into the region 2 to be solidified and improved in the solidified pile 8 and the region 3 in the passive earth pressure region R where liquefaction is expected at the time of an earthquake, as shown in FIG. ', 3' is formed below the groundwater level 101.

  The injection of air A into the region 2 to be solidified and improved by the solidified pile 8 and the region 3 in the passive earth pressure region R where liquefaction is expected at the time of an earthquake is caused by boring holes 6 drilled vertically and obliquely downward. This is performed after the air injection tube 7 is inserted to the lower end of 6 ', but in the middle of inserting the air injection tube 7' to the lower end of each boring hole 6, 6 ', or the air injection tube 7 is connected to each boring hole 6, You may perform in the middle of pulling up from the lower end of 6 '. The air injection tube 7 used here has, for example, a large number of fine through holes as injection holes for injecting air at the tip, but a large number of fine through holes for air injection are provided from the tip to the middle part. It may be good.

  In this way, the region 2 that is solidified and improved by the solidified pile 8 of the ground 1 directly below the foundation 11a of the retaining wall 11 and the region 2 ′ that is desaturated into the region 3 that is expected to be liquefied during an earthquake in the passive earth pressure region R. , 3 'are respectively formed below the groundwater level 101, it is possible to reliably prevent liquefaction of the ground 1 directly below the foundation 11a of the retaining wall 11 during an earthquake. In this case, each boring hole 6, 6 ′ from the ground 1 a in the site where the retaining wall 11 is provided in the region 2 to be solidified and improved by the solidified pile 8 and the region 3 in the passive earth pressure region R where liquefaction is expected at the time of an earthquake. Is excavated vertically and obliquely downward, and the air injection pipe 7 is inserted into each of the boring holes 6 and 6 ′ and air A is injected from the air injection pipe 7. An area 2 that can be constructed with low cost by a small machine and is solidified and improved by the solidified pile 8 of the ground 1 directly below the foundation 11a of the retaining wall 11 and an area where the passive earth pressure area R is expected to be liquefied during an earthquake. The liquefaction countermeasure 3 can be easily and reliably performed at low cost. Thereby, it is possible to increase the bearing capacity of the retaining wall 11 by reliably preventing the liquefaction of the ground 1 immediately below the foundation 11a of the retaining wall 11 at the time of an earthquake by economical construction. The retaining wall 11 can be reliably prevented from sinking or tilting, and the retaining wall 11 can be sufficiently stable.

  Further, avoiding the foundation 11a of the retaining wall 11, each of the boring holes 6, 6 'is solidified and improved by the solidified pile 8 in the vertical direction and obliquely downward from the ground 1a of the ground 1 in the passive earth pressure region R. Excavation is performed up to the region 3 where liquefaction is expected at the time of the earthquake, and an air injection pipe 7 is inserted into each of the excavated bore holes 6 and 6 ′ to solidify the air A from the tip of the air injection pipe 7. Since it is injected into the region 2 where solidification is improved in the region 2 and the region 3 where the liquefaction is expected in the passive earth pressure region R, solidification is improved with the solidified pile 8 on the ground 1 directly below the foundation 11a of the existing retaining wall 11. This can be easily applied when the region 2 and the passive earth pressure region R are unsaturated in the region 3 where liquefaction is expected during an earthquake. That is, the construction is simple, the construction cost can be suppressed, and the ground 1 immediately below the foundation 11a of the retaining wall 11 can be easily and reliably unsaturated.

  Furthermore, the area 3 where liquefaction is expected in the passive earth pressure area R around the area 2 to be solidified and improved by the solidified pile 8 of the ground 1 directly below the foundation 11a of the retaining wall 11 is the site of the retaining wall 11 Even when it falls outside the boundary, it takes outside the boundary of the retaining wall 11 site by excavating the boring holes 6 and 6 ′ vertically and diagonally downward from the ground 1 a in the boundary of the retaining wall 11 site. In the passive earth pressure region R, the air A can be easily and reliably injected into the region 3 where liquefaction is expected during an earthquake through the air injection pipe 7 and can be desaturated. That is, the desaturation method of injecting air A into the ground 1 can be improved in the original ground state, and there is no harm because what is injected is the air A existing in the natural world. By drilling the boring holes 6 and 6 'vertically and diagonally downward, air A can be injected into the passive earth pressure region R, and there is no need to install a construction yard etc. outside the site, so it is easy in a gentle construction environment. And it can be reliably and inexpensively constructed.

<Sixth Embodiment>
FIG. 10A is an explanatory diagram before construction of the ground improvement method of the sixth embodiment of the present invention, FIG. 10B is an explanatory diagram during construction of the method, and FIG. 11 is an explanatory diagram after construction of the method. It is.

  In the ground improvement method of the sixth embodiment, first, the region 2 that is stably required for the loading load of the retaining wall (structure) 11 is improved by solidifying the solidified pile 8, and then liquefied during an earthquake. Of the ground 1 in which the retaining wall 11 is stabilized, by injecting air A into the areas 2, 4 and 5 of the ground 1 necessary to ensure the stability of the retaining wall 11, the areas 2, 4 and 5 of the ground 1 are desaturated. . Accordingly, the retaining wall 11 is stabilized by increasing the strength of the ground 1 with respect to the loading load of the retaining wall 11, and the retaining wall 11 is stabilized with desaturation of the ground 1 against liquefaction of the ground 1. Therefore, this is a method capable of reducing the cost without increasing the strength of the ground 1 more than necessary, and will be described in detail with reference to FIGS. 10 (a), 10 (b) and FIG.

  First, as shown in FIG. 10 (a), a predetermined number of columnar solidified piles 8 are disposed in the ground 1 such as sand ground directly under the foundation 11a of the retaining wall 11 made of reinforced concrete. The ground 1 immediately below 11 a is solidified and improved by the solidified pile 8. In this case, the solidified pile 8 is constructed to a depth at which stability can be ensured with respect to the foundation 11 a of the retaining wall 11. A region to be solidified and improved by the solidified pile 8 is denoted by reference numeral 2 in FIG. 10, a region immediately below the region 2 to be solidified and improved by the solidified pile 8 is denoted by reference numeral 4 in FIG. 10, and a region 2 to be solidified and improved by the solidified pile 8 A stress distribution region (region 5 where liquefaction is expected during an earthquake) around the region 4 immediately below is indicated by a symbol R ′ in FIG. 10, and a stress distribution angle is indicated by a symbol α ′ in FIG. Here, the stress distribution region R ′ means that when the region 4 directly below the improved body 2 receives a force in the horizontal direction due to the earthquake horizontal acceleration during an earthquake, the region 4 immediately below the improved body 2 attempts to move horizontally. The area of the ground to be pressed is referred to, and the stress dispersion angle α ′ is an angle at which the ground 1 collapses in the stress dispersion area R ′. Both the stress dispersion area R ′ and the stress dispersion angle α ′ are known calculations. Required by the method. In addition, the improvement width of the region 5 in which liquefaction is expected at the time of the earthquake is an improvement to the width of the region in which the load (upload) of the retaining wall 11 is stress-dispersed on the bottom surface of the region 2 solidified and improved by the solidified pile 8. The improvement depth of the region 5 is an improvement up to the non-liquefaction layer (support layer) 1b where the liquefaction does not occur.

  Next, as shown in FIG. 10 (b), a region 4 just below the region 2 to be solidified and improved by the plurality of columnar solidified piles 8 and a region 4 just below the region 2 to be solidified and improved by the solidified pile 8 From the ground 1a of the ground 1 to the boring holes 6 and 6 'vertically and obliquely to the lower liquefaction layer (support layer) 1b below the region 5 where liquefaction is expected in the surrounding stress distribution region R' Drill down. In this case, a plurality of boring holes 6, 6 ′ are formed while maintaining an interval and an oblique angle at which air A can be reliably injected into the ground 1.

  Next, the air injection pipe 7 is inserted to the lower end of each bored hole 6, 6 ′ excavated vertically and obliquely downward. Then, as shown in FIG. 10 (b), a region 4 immediately below the region 2 to be solidified and improved by the solidified pile 8 from the air injection pipe 7 and a region 5 in which liquefaction is expected at the time of an earthquake in its stress dispersion region R ′. By injecting air A into the region 2, the region 2 solidified and improved by the solidified pile 8, the region 4 just below the region 2 solidified and improved by the solidified pile 8, and the region where the stress dispersion region R ′ is expected to be liquefied during an earthquake As shown in FIG. 11, the unsaturated regions 2 ', 4' and 5 'are formed below the groundwater level 101 by injecting air A into the air.

  The region 2 to be solidified and improved by the solidified pile 8, the region 4 just below the region 2 to be solidified and improved by the solidified pile 8, and the stress dispersion region R ′ of the air A into the region 5 where liquefaction is expected during an earthquake. The injection is performed after the air injection pipe 7 is inserted to the lower end of each boring hole 6, 6 ′ excavated vertically and obliquely downward, and the air injection pipe 7 is inserted to the lower end of each boring hole 6, 6 ′. You may perform in the middle of inserting or in the middle of pulling up air injection pipe 7 from the lower end of each boring hole 6 and 6 '. The air injection tube 7 used here is, for example, provided with a number of fine through holes for air injection at the tip, but provided with a number of fine through holes as injection holes for air injection from the tip to the middle part. It may be good.

  Thus, the earthquake is caused in the region 2 solidified and improved by the solidified pile 8 of the ground 1 directly below the foundation 11 a of the retaining wall 11, the region 4 directly below the region 2 solidified and improved by the solidified pile 8, and its stress dispersion region R ′. By forming the unsaturated regions 2 ', 4' and 5 'below the groundwater level 101 or lower in the region 5 where liquefaction is expected at times, the ground 1 immediately below the foundation 11a of the retaining wall 11 in the event of an earthquake Liquefaction can be reliably prevented. In this case, the retaining wall 11 is located in the region 2 solidified and improved by the solidified pile 8, the region 4 immediately below the region 2 solidified and improved by the solidified pile 8, and the region 5 where liquefaction is expected during an earthquake in its stress dispersion region R ′. Is drilled in the vertical direction and obliquely downward from the ground 1a in the site provided with the air, and the air is drilled in the vertical direction and obliquely downward. Since it is a simple method of inserting the injection pipe 7 and injecting the air A from the air injection pipe 7, it can be constructed at a low cost by a small machine, and the ground directly below the foundation 11 a of the retaining wall 11. Measures for liquefaction in region 2 where solidification pile 8 is solidified, region 4 just below solidification pile 8 is solidified and improved, and region 5 where liquefaction is expected during an earthquake in its stress dispersion region R ′ Easy and reliable at low costThereby, it is possible to increase the bearing capacity of the retaining wall 11 by reliably preventing the liquefaction of the ground 1 immediately below the foundation 11a of the retaining wall 11 at the time of an earthquake by economical construction. The retaining wall 11 can be reliably prevented from sinking or tilting, and the retaining wall 11 can be sufficiently stable.

  Further, avoiding the foundation 11 a of the retaining wall 11, each of the boring holes 6, 6 ′ is solidified and improved by the solidified pile 8 and the solidified pile 8 in the vertical direction and obliquely downward from the ground 1 a of the ground 1. Drilled to the region 4 directly below the region 2 and the stress distribution region R ′ to the region 5 where liquefaction is expected in the event of an earthquake and drilled in the vertical direction and obliquely downward. The air injection pipe 7 is inserted into 6 'and the area 2 where the air A is solidified and improved by the solidified pile 8 from the tip of the air injection pipe 7 and the area 4 which is further directly below the area 2 where the solidified and improved is solidified by the solidified pile 8 and its Since it is injected into the region 5 where liquefaction is expected at the time of an earthquake in the stress dispersion region R ′, the solidification pile 8 in the solidified pile 8 of the ground 1 directly below the foundation 11 a of the existing retaining wall 11 and the solidified pile 8 The region 4 directly below the region 2 to be solidified and its stress It can be easily applied to a case where the region 5 liquefaction is expected during an earthquake in diffusing region R 'each unsaturated. That is, the construction is simple, the construction cost can be suppressed, and the ground 1 immediately below the foundation 11a of the retaining wall 11 can be easily and reliably unsaturated.

  Further, a region 5 where liquefaction is expected at the time of an earthquake in the stress distribution region R ′ around the region 4 further below the region 2 to be solidified and improved by the solidified pile 8 of the ground 1 immediately below the foundation 11a of the retaining wall 11, Even when it is outside the boundary of the retaining wall 11 site, the drilling holes 6 and 6 'are excavated from the ground 1a in the boundary of the retaining wall 11 in the vertical direction and obliquely downward. Air A can be easily and reliably injected into the region 5 where liquefaction is expected in the event of an earthquake in the stress distribution region R ′ outside the boundary of the site via the air injection pipe 7 and can be desaturated. . That is, the desaturation method of injecting air A into the ground 1 can be improved in the original ground state, and there is no harm because what is injected is the air A existing in the natural world. By drilling the drilling holes 6 and 6 'vertically and obliquely, air A can be injected into the stress distribution region R', and it is not necessary to provide a construction yard etc. outside the site area. It can be reliably constructed at low cost.

<Modification of Sixth Embodiment>
FIG. 12 is explanatory drawing in the middle of construction of the modification of the ground improvement method of 6th Embodiment of this invention.

  In the modification of the sixth embodiment, as shown in FIG. 12, the region 4 further below the region 2 to be solidified and improved by the plurality of columnar solidified piles 8 and the region 2 to be further solidified and improved by the solidified pile 8. In the stress distribution region R ′ around the region 4, the boring hole 6 ′ is inclined obliquely downward from the ground 1 a of the ground 1 to the non-liquefaction layer (support layer) 1 b below the region 5 where liquefaction is expected during an earthquake. And then drilling by changing the horizontal direction from the non-liquefaction layer 1b, and then freely forming a flexible air injection pipe 7 'along the drilling hole 6' whose shape of excavation is variable. Deform and insert. Then, by injecting air A from the air injection pipe 7 ′ to the region 4 just below the region 2 to be solidified and improved by the solidified pile 8 and to the region 5 where liquefaction is expected at the time of an earthquake in its stress dispersion region R ′, Air A is injected into the region 2 where solidification is improved by the solidified pile 8, the region 4 just below the region 2 where solidification is improved by the solidified pile 8, and the region 5 where liquefaction is expected during an earthquake in the stress dispersion region R ′. Thus, as shown in FIG. 11, the unsaturated regions 2 ′, 4 ′ and 5 ′ are formed below the groundwater level 101.

  At this time, the air into the region 5 where solidification is improved by the solidified pile 8 and the region 4 immediately below the region 2 where solidification is improved by the solidified pile 8 and the region 5 where the stress dispersion region R ′ is expected to be liquefied during an earthquake. The injection of A is performed after the flexible air injection pipe 7 'is inserted to the tip of the boring hole 6' having a variable excavation shape, but in the middle of inserting the air injection pipe 7 'to the tip of the boring hole 6'. Alternatively, it may be performed in the middle of lifting the air injection pipe 7 'from the tip of the boring hole 6'. The air injection tube 7 'used here has, for example, a large number of fine through holes as injection holes for air injection at the tip, but there are many fine through holes for air injection from the tip to the middle part. It may be provided.

  In this way, the retaining wall is located in the region 2 solidified and improved by the solidified pile 8, the region 4 just below the region 2 solidified and improved by the solidified pile 8, and the region 5 where liquefaction is expected at the time of an earthquake in its stress dispersion region R ′. 11 is excavated from the ground 1a in the premises in the site obliquely downward, and the excavation is changed in the horizontal direction from the middle, and the excavation shape is changed into a boring hole 6 ′. The flexible air injection pipe 7 'is freely deformed and inserted along the air injection pipe 7' so that the air A is injected from the air injection pipe 7 '. Liquefaction is expected at the time of an earthquake in the region 2 solidified and improved by the solidified pile 8 of the ground 1 immediately below the foundation 11a, the region 4 immediately below the region 2 solidified and improved by the solidified pile 8 and its stress dispersion region R ′. Measures for liquefaction in area 5 It can be performed in a single and reliable low cost. Thereby, it is possible to increase the bearing capacity of the retaining wall 11 by reliably preventing the liquefaction of the ground 1 immediately below the foundation 11a of the retaining wall 11 at the time of an earthquake by economical construction. The retaining wall 11 can be reliably prevented from sinking or tilting, and the retaining wall 11 can be sufficiently stable.

  Further, a region 5 where liquefaction is expected at the time of an earthquake in the stress distribution region R ′ around the region 4 further below the region 2 to be solidified and improved by the solidified pile 8 of the ground 1 directly below the foundation 11a of the retaining wall 11 Even when it falls outside the boundary of the retaining wall 11 site, by excavating the borehole 6 'from the ground 1a within the boundary of the retaining wall 11 in the horizontal direction from diagonally below, In the stress distribution region R ′ applied outside the boundary, the air A can be easily and reliably injected into the region 5 where liquefaction is expected during an earthquake through the flexible air injection tube 7 ′, and can be desaturated. it can. In other words, the desaturation method for injecting air A into the ground 1 can be improved while still in the original ground state, and since it is air A that exists in nature, there is no harm and boring from within the site area. By drilling the hole 6 'diagonally, the air A can be easily injected into the stress dispersion region R', and it is not necessary to provide a construction yard etc. outside the site area. It can be reliably constructed at low cost.

<Seventh embodiment>
FIG. 13 is explanatory drawing in the middle of construction of the ground improvement method of 7th Embodiment of this invention.

  In the ground improvement method of the seventh embodiment, first, the area 2 that is stably required for the load on the lifeline pipe (structure) 12 is improved by the solidification treatment of the solidified pile (improved pile) 8, Next, the region 2 of the ground 1 is desaturated by injecting air A into the region 2 of the ground 1 necessary to ensure the stability of the lifeline piping 12 in the ground 1 where liquefaction occurs during an earthquake. . As a result, the lifeline piping 12 is stabilized by increasing the strength of the ground 1 with respect to the loading load of the lifeline piping 12, and the lifeline due to the desaturation of the ground 1 with respect to the liquefaction of the ground 1. This is a method capable of reducing the cost without increasing the strength of the ground 1 more than necessary because the piping 12 is stabilized, and will be described in detail below with reference to FIG.

  First, as shown in FIG. 13, a predetermined number of cylindrical solidified piles 8 are arranged in the ground 1 such as sand ground directly under the lifeline piping 12 that is expected to be liquefied during an earthquake, and the lifeline piping is arranged. The ground 1 immediately below 12 is solidified and improved by the solidified pile 8. In this case, the solidified pile 8 is constructed to a depth where stability can be ensured for the concrete bottom plate 13 of the lifeline pipe 12. A region to be solidified and improved by the solidified pile 8 is denoted by reference numeral 2 in FIG.

  Next, as shown in FIG. 13, a boring hole 6 is excavated in a vertical direction from the ground 1 a of the ground 1 in a region 2 to be solidified and improved by a plurality of columnar solidified piles 8. In this case, a plurality of boring holes 6 are formed at intervals at which the injected air can surely permeate into the ground 1. The drilling direction of the boring hole 6 is not limited to the vertical direction, and the boring hole 6 may be drilled obliquely downward in the region 2 to be solidified and improved from the ground 1a on both sides of the lifeline pipe 12 of the ground 1.

  Next, the air injection tube 7 is inserted to the lower end of the boring hole 6. Then, as shown in FIG. 13, by injecting air A from the air injection pipe 7 to the region 2 to be solidified and improved by the solidified pile 8, the air A is injected into the region 2 to be solidified and improved by the solidified pile 8, An unsaturated region is formed below the groundwater level 101.

  The injection of the air A into the region 2 to be solidified and improved by the solidified pile 8 is performed after the air injection pipe 7 is inserted to the lower end of the boring hole 6, but the air injection pipe 7 is lowered to the lower end of the boring hole 6. You may perform in the middle or in the middle of pulling up the air injection pipe 7 from the lower end of the boring hole 6. The air injection tube 7 used here has, for example, a large number of fine through holes as injection holes for injecting air at the tip.

  In this way, by forming the unsaturated region in the region 2 to be solidified and improved by the solidified pile 8 of the ground 1 directly below the lifeline piping 12 below the groundwater level 101, the region immediately below the lifeline piping 12 at the time of an earthquake. The liquefaction of the ground 1 can be reliably prevented. In this case, a boring hole 6 is excavated in the vertical direction from both sides of the lifeline pipe 12 on the ground 1a in the region 2 to be solidified and improved by the solidified pile 8, and an air injection pipe 7 is inserted into the boring hole 6, Since it is a simple method of simply injecting air A from the air injection pipe 7, it can be constructed at a low cost by a small machine, and is solidified as a whole by the solidified pile 8 of the ground 1 directly under the lifeline pipe 12. The liquefaction countermeasure of the area | region 2 to improve can be performed simply and reliably at low cost. As a result, it is possible to increase the bearing capacity of the lifeline pipe 12 by reliably preventing the liquefaction of the ground 1 immediately below the lifeline pipe 12 at the time of an earthquake by economical construction. It is possible to reliably prevent the lifeline pipe 12 from sinking or tilting, and the lifeline pipe 12 can be sufficiently stable.

  Furthermore, since the boring hole 6 is excavated from both sides of the lifeline pipe 12 on the ground 1a of the ground 1 in the vertical direction, the construction is simple and the construction cost can be reduced. Further, when the borehole 6 cannot be excavated by hitting the lifeline pipe 12, the lifeline pipe 12 is avoided and the solidification improvement is performed from the ground 1a of the ground 1 by the solidified pile 8 toward the region 2. Drilling the boring hole diagonally downward, inserting the air injection pipe 7 into the drilled boring hole, and injecting air A from the tip of the air injection pipe 7 into the region 2 where the solidified pile 8 solidifies and improves. By doing so, an unsaturated region may be formed. In this case, since the boring hole is excavated obliquely downward from the ground 1a of the ground 1, the construction is easy and the construction cost can be suppressed, and the ground 1 directly below the lifeline pipe 12 can be easily and reliably provided. Can be desaturated.

  Further, in the ground improvement method of the seventh embodiment, air A is injected into the region 2 where the ground 1 immediately below the lifeline pipe 12 is solidified and improved by the solidified pile 8, and the region 2 where the solidification is improved is unsaturated. However, the air A was injected into the passive earth pressure area around the area where the ground 1 immediately below the lifeline piping 12 was solidified and improved, or the area where the liquefaction is expected in the main earth pressure area. You may make it desaturate each area | region where liquefaction is anticipated at the time of an earthquake in the passive earth pressure area | region or main earth pressure area | region around the area | region which solidifies and improves. In this case as well, liquefaction countermeasures in each region can be easily and reliably performed at low cost, the supporting force of the lifeline pipe 12 can be increased, and the stability of the lifeline pipe 12 is sufficiently secured. be able to.

<Eighth Embodiment>
FIG. 14 is explanatory drawing in the middle of construction of the ground improvement method of 8th Embodiment of this invention.

  In the ground improvement method of the eighth embodiment, the region 2 that is stably required for the loading load is ground improved by a solidification process such as a deep mixing process, and then liquefaction is expected during an earthquake. By injecting air A from the air injection pipe 7 inserted in the borehole 6 into the ground 1 surrounded by the improved body 9, the ground 1 below the groundwater level 101 surrounded by the lattice-shaped improved body 9 is unsaturated. Turn into.

  Thereby, the improvement width | variety of the grid | lattice-like part of the grid-like improvement body 9 can be made small, or a grid-like space | interval can be enlarged, and the depth of the grid-like improvement body 9 can be made shallow. Construction can be simplified and construction costs can be reduced. As a result, liquefaction during an earthquake can be more effectively prevented, and the structure can be reliably supported.

  According to the first to fifth embodiments and the seventh and eighth embodiments, the boring hole is excavated from the ground in the vertical direction or obliquely downward, and air is injected into the bored hole excavated in these directions. While inserting a pipe and injecting air into the ground where liquefaction is expected during an earthquake, as in the modification of the sixth embodiment, the borehole is excavated obliquely downward from the ground. Drill in the horizontal direction from the middle, insert the air injection pipe freely deformed along the drilling hole with variable drilling shape, and inject air into the ground where liquefaction is expected during an earthquake You may make it inject | pour. If the air injection pipe is freely deformed and inserted along the drilling hole with a variable drilling shape, air will enter the ground outside the site boundary where liquefaction is expected during the earthquake from within the site boundary of the structure. Can be easily and reliably injected, and can be desaturated, and it is not necessary to provide a construction yard outside the site, so it should be constructed easily and reliably at a low cost in a gentle construction environment. Can do.

1 Ground 1a Ground 2 Area to be solidified 2 'Desaturated area 3 Area where liquefaction occurs in the passive earth pressure area 3' Area where the passive earth pressure area is desaturated 4 Directly below the area to be solidified Area 4 'Area where the area just below the area to be solidified is desaturated 5 Area where the liquefaction occurs in the passive earth pressure area around the area just below the area to be solidified 5' Unsaturated region 6, 6 'Boring hole 7, 7' Air injection pipe
8 Multiple solidified piles (multiple pillars)
10 Road embankment (structure)
11 Retaining wall (structure)
12 Lifeline piping (structure)
A Air R Passive earth pressure area 101 Groundwater level

Claims (3)

When improving the ground directly under the structure, the ground directly under the structure is stabilized by solidification treatment, and for liquefaction during an earthquake, the ground where liquefaction occurs during the earthquake A ground improvement method of stabilizing the structure by desaturating the ground area by injecting air into the ground area necessary to ensure the stability of the structure,
The area that is stably necessary for the load of the structure on the ground directly below the structure is improved by solidification treatment using a plurality of columnar piles , and then the ground is obtained by solidification treatment using the plurality of columnar piles. A ground improvement method characterized by forming an unsaturated region by injecting the air below the groundwater level in the region between the improved columnar piles . The ground improvement method according to claim 1,
When injecting the air, forming a borehole from the earth, in the following, foundation improvement characterized by injecting the air from the injection hole of the air injection pipe to the borehole by inserting the air injection tube Method. The ground improvement method according to claim 1 ,
A ground improvement method characterized by further forming an unsaturated region by injecting the air below the groundwater level in a passive earth pressure region around a region that is stably required for an overload of the structure. .

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