JP2012136898A - Earth retaining wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the formation and progress of a crack from being caused by deformation of a soil cement pillar line wall.SOLUTION: An earth retaining wall 10 comprises a soil cement pillar line wall 14 that is constructed on ground 16 and that surrounds an excavation section 20. The excavation section 20 is excavated to an excavation surface 18 after the completion of the earth retaining wall 10. A lower portion of the soil cement pillar line wall 14 is constructed up to a position deeper than the excavation surface 18. The soil cement pillar line wall 14 is constructed like a wall by making outer peripheral surfaces of adjacent soil cement pillars 12 overlap each other. In this case, the soil cement pillars 12 make the ground 16 being excavated by means of an auger not shown in Fig., and excavated soil and cement milk are mixed and agitated to be constructed in a cylindrical shape. Fibers 22 for reinforcement are mixed in the soil cement pillar line wall 14.

Description

  The present invention relates to a mountain retaining wall.

  For excavation of the ground where a water stop function is required, a mountain wall constructed of soil cement column walls is widely used. Here, since the soil cement column wall is manufactured by mixing the soil of the original ground and cement milk, the strength is lower than that of general concrete. For this reason, a core material such as H-shaped steel is embedded below the excavation surface, and the core material bears earth pressure from the natural ground, and the soil cement column wall shares the water stop function. . From such a background, the use of the soil cement column wall was limited to the mountain wall that does not bear the vertical load, and it was considered that it could not be used for other purposes. Furthermore, even if the earth pressure can be borne by the core material, it is not possible to suppress the generation and growth of cracks due to deformation due to an external force such as an earthquake, and there is a problem that securing of the water stop function is insufficient. .

Then, the technique which increases the intensity | strength of a soil cement pillar row wall and bears the vertical load of a building to a soil cement pillar row wall is disclosed (patent document 1).
That is, Patent Document 1 increases the amount of cement in cement milk to be mixed with soil only in the core material root part when constructing the soil cement column wall, and increases the strength of the core base part. It is also used as a support pile that supports the building.

  However, in patent document 1, in order to raise the intensity | strength of a soil cement column row wall, the amount of cement in cement milk is increased, and cost increases by the increase in the amount of cement. In addition, the labor for managing the cement amount also increases. Furthermore, crack generation and growth due to deformation of the soil cement column wall cannot be suppressed.

Japanese Patent No. 4466418

  An object of this invention is to provide the mountain retaining wall which suppresses generation | occurrence | production and growth of the crack by deformation | transformation of a soil cement column wall in view of the said fact.

  The mountain retaining wall according to the first aspect of the present invention is a soil cement column wall constructed by wrapping outer peripheral surfaces of soil cement columns, and a reinforcing wall mixed in the soil cement column wall. And a fiber.

According to the first aspect of the present invention, the soil cement column wall is constructed by wrapping the outer peripheral surface of the soil cement column, and fibers are mixed inside the soil cement column wall.
As a result, the mixed reinforcing fibers resist the tensile force acting on the soil cement column wall and increase the strength. As a result, even if the soil cement column wall is deformed by an external force such as an earthquake, the mixed fibers resist the generation and growth of cracks. That is, the generation and growth of cracks are suppressed and the water stop function is ensured. Furthermore, for example, a soil cement column wall can be used as a column in the reverse driving method.

The invention according to claim 2 is the mountain retaining wall according to claim 1, characterized in that a core material embedded below the excavation surface is embedded in the soil cement column wall. .
According to the second aspect of the present invention, the core material is embedded below the excavation surface. Thereby, since the earth pressure from a natural ground can be borne on a core material, excavation depth can be deepened. At this time, since the soil cement column wall is reinforced with fibers, the burden of the core material embedded in the soil cement column wall can be reduced. As a result, it is possible to reduce the number of core materials used and to reduce the core material diameter.

  The mountain retaining wall according to the invention described in claim 3 is a soil cement column wall in which a plurality of rows are constructed on the ground mountain side by wrapping the outer peripheral surface of the soil cement column, and any of the soil cement column walls It is characterized by having reinforcing fibers mixed in the inside of the row and a core material embedded in an arbitrary row of the soil cement column wall and rooted below the excavation surface.

According to the third aspect of the present invention, the multiple rows of soil cement column walls are constructed on the natural ground side by wrapping the outer peripheral surfaces of the soil cement columns. Reinforcing fibers are mixed in an arbitrary row of the soil cement column wall. Furthermore, a core material embedded below the excavation surface is embedded in an arbitrary row of the soil cement column wall.
Thereby, a plurality of soil cement column walls share and bear earth pressure from the natural ground. As a result, the strength required for the mountain retaining wall can be easily adjusted. Furthermore, even if the soil cement column wall is deformed by an external force such as an earthquake, the mixed fibers resist the generation and growth of cracks. As a result, generation and growth of cracks are suppressed, and a water stop function is ensured. Furthermore, the utilization range of the soil cement column wall can be expanded, such as utilization as a column in the above-described reverse driving method.

According to a fourth aspect of the present invention, in the mountain retaining wall according to any one of the first to third aspects, the fiber is mixed only in a portion where bending stress acts on the soil cement column wall. It is characterized by having.
According to invention of Claim 4, a fiber is mixed only in the part to which the bending stress acts in the soil cement column wall. That is, by reinforcing only the range that requires reinforcement, it is possible to ensure the bending strength required for the soil cement column wall, and to reduce the amount of fibers to be mixed.

  According to a fifth aspect of the present invention, in the mountain retaining wall according to any one of the first to fourth aspects, the fiber is a lower part of the soil cement column wall where the lower part of the core material is fixed. It is characterized in that a stud is provided in the lower part of the core material.

According to invention of Claim 5, the fiber is mixed in the lower part of the soil cement column wall where the lower part of a core material is fixed. A stud is provided at the bottom of the core material. As a result, the soil cement column wall and the core material can be firmly fixed.
That is, by reinforcing only the fixing portion of the core material that requires bending strength, the bending strength required for the soil cement column wall can be secured, and the amount of mixed fibers can be reduced.

The invention according to claim 6 is the mountain retaining wall according to any one of claims 1 to 3, wherein the soil cement column wall sews a slip surface on which a landslide is predicted. It is characterized by being built.
According to the sixth aspect of the present invention, the soil cement column wall is constructed so as to sew a slip surface on which a landslide is predicted. Thereby, the landslide in an inclined land can be suppressed by the soil cement column wall.

  The invention according to claim 7 is the mountain retaining wall according to any one of claims 1 to 6, wherein the fiber has a length ratio to the thickness of the fiber material adjusted to 1000 or more. It is a polypropylene fiber, and the polypropylene fiber is mixed in the soil cement column wall within a range of 0.4 to 2.0% by volume.

According to the seventh aspect of the present invention, the soil cement column has a volume ratio of 0.4 to 2.0% of the polypropylene fiber in which the ratio of the length to the thickness of the fiber material is adjusted to 1000 or more. It is mixed in the row wall.
That is, polypropylene fibers of appropriate dimensions and mixed with the appropriate amount resist the tensile force. Thereby, the intensity | strength of a soil cement pillar row wall can be raised, and generation | occurrence | production of the crack to a soil cement pillar row wall and growth can be suppressed. Moreover, since an inexpensive polypropylene fiber can be used, an increase in cost can be suppressed.

  Since this invention is set as the said structure, generation | occurrence | production and the growth of a crack by deformation | transformation of a soil cement column row wall can be suppressed.

It is a figure which shows the basic composition of the mountain retaining wall which concerns on the 1st Embodiment of this invention. It is a schematic diagram which shows the state which mixed the fiber in the soil cement pillar. It is a block diagram of the excavation apparatus which mixes a fiber in a soil cement pillar. It is a figure which shows the effect of the mountain retaining wall which concerns on the 1st Embodiment of this invention. It is a figure which shows the example of expansion | deployment of the mountain retaining wall which concerns on the 1st Embodiment of this invention. It is a figure which shows the basic composition of the mountain retaining wall which concerns on the 2nd Embodiment of this invention. It is the figure which shows the basic composition of the mountain retaining wall which concerns on the 3rd Embodiment of this invention, and the figure which shows the example of an expansion | deployment. It is a figure which shows the basic composition of the mountain retaining wall which concerns on the 4th Embodiment of this invention.

(First embodiment)
As shown in FIG. 1, the mountain retaining wall 10 according to the first embodiment has a soil cement column wall 14 constructed on the ground 16 and surrounding the excavation part 20. The excavation part 20 is excavated to the excavation surface 18 after completion of the mountain retaining wall 10. The lower part of the soil cement column wall 14 is constructed to a position deeper than the excavation surface 18.
The soil cement column wall 14 is constructed in a wall shape by wrapping the outer peripheral surfaces of adjacent soil cement columns 12. Here, the soil cement pillar 12 is constructed in a cylindrical shape by excavating the ground 16 with an auger (not shown), and mixing and stirring the excavated soil and cement milk.

As a result, it is possible to prevent the ground 16 on the natural ground side from collapsing into the excavation part 20 surrounded by the mountain retaining wall 10 and to exhibit a water stop function, thereby enabling excavation of the excavation part 20.
Reinforcing fibers 22 described later are mixed in the soil cement column wall. That is, the mixed reinforcing fibers 22 increase the strength of the soil cement column wall. As a result, it is possible to more strongly resist, for example, earth pressure from the natural mountain side acting on the soil cement column wall and horizontal force at the time of the earthquake than when there is no reinforcing fiber 22. .

  Thereby, the excavation depth of the excavation part 20 can be increased. Moreover, even if the soil cement column wall 14 is deformed by an external force such as an earthquake, the generation and growth of cracks are suppressed and the water stop function is ensured. Furthermore, for example, the soil cement column wall 14 can be used as a column in the reverse driving method.

Next, the mixed fibers will be described with reference to FIGS.
As shown in FIG. 2, it is desirable that the fibers 22 mixed in the soil cement column wall 14 have mechanical properties with a breaking strength of 200 to 1200 MPa and a Young's modulus of 2 to 15 GPa. For example, polypropylene fiber is applicable.

The diameter of the fiber 22 is preferably in the range of 10 to 50 μm. This is because a certain amount of size is necessary to ensure sufficient contact between the soil cement column wall 14 and the fiber 22, while when the diameter of the fiber 22 becomes too large, the fiber 22 is bent. This is because it is difficult to intertwine each other, and there is a limit to the size.

  Even if the diameter is an appropriate size, as shown in FIG. 2C, in the case of the fiber 23 having a linear shape, the fiber 23 and the fiber 23 are not entangled with each other. For this reason, a sufficiently large frictional resistance cannot be obtained between the soil cement column wall 14 and the fiber 23. As a result, as shown in FIG. 2D, even if the fibers 23 are mixed, generation of cracks 36 on the surface of the soil cement column wall 14 and growth of the cracks 36 cannot be suppressed.

  On the other hand, as shown in FIG. 2A, in the bent shape of the fiber 22, the fiber 22 and the fiber 22 can be easily entangled with each other, and the frictional resistance can be increased. As a result, a sufficiently large frictional resistance acts between the soil cement column wall 14 and the fiber 23 as shown in FIG. By this frictional resistance, generation of cracks 36 on the surface of the soil cement column wall 14 and growth of the cracks 36 can be suppressed.

In addition, in order to make the fiber 22 into a bent shape and to exert a sufficiently large frictional resistance between the soil cement column wall 14 and the fiber 22, the larger the aspect ratio (the ratio of the length to the thickness of the fiber) is, the larger the aspect ratio is. It is advantageous. Specifically, the aspect ratio is desirably 1000 or more.
Furthermore, if a knot-like or massive anchor portion larger than the fiber diameter is provided at both ends of the fiber 22, the frictional resistance between the soil cement column wall 14 and the fiber 23 can be further increased.

The mixing ratio of the soil cement column wall 14 and the fiber 22 is such that the fiber 22 having an aspect ratio adjusted to 1000 or more is in a range of 0.4 to 2.0% in volume ratio with the soil cement column wall 14. It is desirable to mix. Thereby, the fiber 22 resists the tensile force, and the generation and growth of the crack 36 on the surface of the soil cement column wall 14 can be suppressed.

Next, the construction method of the soil cement column wall 14 mixed with the fibers 22 will be described.
As shown in FIG. 3, the excavator 60 has two rods 64A and 64B having an auger portion 62 attached to the lower end, and supplies the fiber 22 between the two rods 64A and 64B. A tube 61 is attached. The excavator 60 has a configuration in which a portion of the supply pipe 61 is added to a generally used excavator.

Inside the supply pipe 61 attached between the two rods 64A and 64B, a through hole for sending the fiber 22 is provided, and the upper end of the supply pipe 61 is connected to a fiber supply section (not shown). An injection port 61E is opened at the lower end of the fiber, and the fibers 22 are injected by air pressure from the injection port 61E.

Discharge ports 65A and 65B for discharging cement milk are formed at the lower ends of the rods 64A and 64B. The cement milk flows down the rods 64A and 64B and is supplied to the discharge ports 65A and 65B.

  The rods 64A and 64B are rotatably held at a predetermined distance by fixing members 66U and 66L arranged at two locations above and below. Further, a plurality of stirring blades 67 having inclined surfaces and a plurality of excavation blades 68 are provided from the side walls of the rods 64A and 64B toward the outside in the radial direction. The excavation blade 68 is provided with an excavation bit 69 having a blade portion for excavating the ground 16 when the rods 64A and 64B rotate.

When excavating the ground 16 using the excavator 60, the fiber 22 is sprayed from the supply pipe 61 together with the cement milk, and the auger 62 stirs and mixes the fiber 22, the cement milk, and the soil of the original ground 16. The fibers 22 can be mixed into the row wall 14.
The method using the excavator 60 described above is an example, and the fibers 22 may be mixed into the soil cement column wall 14 by other methods.

Next, the mixing effect of the fibers 22 will be described.
The method of confirming the effect is that three specimens mixed with fibers 22 and three specimens not mixed with fibers 22 are cut out from soil cement pillars constructed under the same conditions, and each is subjected to a uniaxial compression test. Evaluation was made based on the test results.

That is, the test specimen in which the fibers 22 were mixed, while excavating the original ground, the sand and cement milk mixed with the fibers were added, and the soil cement pillar was constructed by mixing and stirring the fibers 22, cement milk and soil. On the other hand, in the test body in which the fiber 22 was not mixed, the soil cement pillar was constructed by stirring and mixing only the cement milk and the soil without introducing the fiber.

FIG. 4 shows the result of the uniaxial compression test. The horizontal axis represents strain (%), and the vertical axis represents uniaxial compressive strength (kgf / cm ² ).
The characteristics A, B, and C shown in FIG. 4A are the characteristics of the three specimens mixed with the fiber 22, and the characteristics AN, BN, and CN shown in FIG. The characteristics of each of the three specimens not mixed are shown.

Comparing FIG. 4A and FIG. 4B, the uniaxial compressive strength of the test body mixed with the fiber 22 is higher in any of the test bodies than the test body in which the fiber 22 is not mixed. 5kgf / cm ² degree is high. The strain is also measured up to a range that is about 1.0% larger. From this, the uniaxial compressive strength is increased and the toughness is also enhanced. It can be seen that this difference is the effect of improving the soil cement column wall by the fibers 22. That is, it can be said that the strength of the soil cement column wall is improved.

  Further, when the variations of the three specimens are examined, since all show the same tendency, it can be seen that the fibers 22 introduced into the center are mixed almost uniformly into the soil cement column.

Next, a development example of this embodiment will be described.
As shown in FIG. 5, in the mountain retaining wall 26 according to the development example, a core material (H-shaped steel) 30 is embedded in a soil cement column wall 28 that constructs the mountain retaining wall 26. The H-section steel 30 is embedded below the excavation surface 18.

  Thereby, since the earth pressure from the natural ground can be borne by the H-section steel 30, the excavation depth can be increased. Moreover, since the soil cement column wall 28 is reinforced with the fibers 22, the burden of the H-section steel 30 embedded in the soil cement column wall 28 can be reduced. As a result, when the earth pressure is small, the number of H-section steels 30 used can be reduced, and the diameter of the H-section steel 30 can be reduced.

  As shown in FIG. 5 (B), the H-shaped steel 30 is not only inserted into all the soil cement columns 12 constituting the soil cement column wall 28, but also when the earth pressure to be borne is small. As shown in FIG. 5 (B), the number of H-section steel 30 inserted may be reduced.

(Second Embodiment)
As shown in FIG. 6 (A), the mountain retaining wall 32 according to the second embodiment wraps the outer peripheral surface of the soil cement column 12 and is constructed in two rows on the ground mountain 16 side. Row walls 38 and 39 are provided. The lower part of the soil cement column wall 38, 39 is constructed up to the bottom of the excavation surface 18. The other configuration is the same as that of the first embodiment. Only parts different from the first embodiment will be described.

  The soil cement column wall 38 is constructed on the excavation part 20 side, and an H-section steel 30 is inserted therein. The H-section steel 30 is embedded under the excavation surface 18. The soil cement column wall 39 is constructed on the ground pile 16 side of the soil cement column wall 38, and reinforcing fibers 22 are mixed therein.

  Thereby, the soil cement column wall 38 and 39 can share and bear the earth pressure from the natural ground 16 side. As a result, the strength required for the retaining wall 32 can be easily adjusted. Furthermore, even if the soil cement column walls 38 and 39 are deformed by an external force such as an earthquake, the mixed fibers 22 resist the generation and growth of cracks. Thereby, generation | occurrence | production and growth of a crack are suppressed and a water stop function is ensured. As a result, the utilization range of the mountain retaining wall 32 can be expanded, such as utilization as a support in the above-described reverse driving method.

Next, a development example of the present embodiment will be described.
As shown in FIG. 6 (B), the pile wall 33 according to the first development example wraps the outer peripheral surfaces of the soil cement pillars 12 and is constructed in two rows on the ground pile 16 side. Walls 38 and 39 are provided. The lower part of the soil cement column wall 38, 39 is constructed up to the bottom of the excavation surface 18.

Here, the mountain retaining wall 33 has a configuration in which the order of the mountain retaining wall 32 and the soil cement column wall 38, 39 according to the second embodiment is changed. That is, the reinforcing fiber 22 is mixed in the soil cement column wall 39 on the excavation part 20 side, and the H-shaped steel 30 is inserted in the soil cement column wall 38 on the ground 16 side.
Thereby, the same effect as the mountain retaining wall 32 which concerns on 2nd Embodiment can be acquired. Other configurations are the same as those of the second embodiment, and a description thereof will be omitted.

  As shown in FIG. 6 (C), the pile wall 34 according to the second development example wraps the outer peripheral surfaces of the soil cement columns 12 so that two columns are constructed on the ground pile 16 side. Walls 39 and 39 are provided. The lower part of the soil cement column wall 39, 39 is constructed to the bottom of the excavation surface 18.

  Here, the mountain retaining wall 34 is configured by replacing the soil cement column wall 38 of the mountain retaining wall 32 according to the second embodiment with a soil cement column wall 39. That is, the reinforcing fiber 22 is mixed in the soil cement column wall 39 on the excavation unit 20 side, and the reinforcing fiber 22 is also mixed in the soil cement column wall 38 on the ground 16 side.

Thereby, when receiving the earth pressure which does not require the H-section steel 30, the same effect as this Embodiment can be acquired.
In the first and second embodiments, the soil cement column wall 38 and 39 constructed in two rows has been described as an example. However, it is not limited to this, and it may be constructed in three or more rows. By mixing the reinforcing fibers 22 in any one or more rows, it is possible to provide a mountain retaining wall that can ensure a water stop function even when receiving a horizontal force during an earthquake or the like.

(Third embodiment)
As shown in FIG. 7A, the mountain retaining wall 40 according to the third embodiment has a soil cement column wall 42 surrounding the excavation part 20. The soil cement column wall 42 wraps the outer peripheral surfaces of the soil cement columns 12, and the lower end portion is constructed up to the bottom of the excavation surface 18.

  Further, the fibers 22 are mixed only in the portion where the bending stress acts inside the soil cement column wall 42. Specifically, the fibers 22 are mixed only in the range of the height H2 above and below the excavation surface 18 in the soil cement column wall 42 constructed at the depth H1. Thereby, a big bending stress acts and the range which needs reinforcement can be reinforced.

  As a result, the bending strength required for the mountain retaining wall 40 can be ensured, and the amount of fibers to be mixed can be reduced. Other configurations are the same as those of the first embodiment, and a description thereof will be omitted.

Next, a development example of the present embodiment will be described.
As shown in FIG. 7B, the mountain retaining wall 44 according to the development example has a soil cement column wall 46 surrounding the excavation part 20. The soil cement column wall 46 wraps the outer peripheral surfaces of the soil cement columns 12, and the lower end portion is constructed up to the bottom of the excavation surface 18.

Further, inside the soil cement column wall 46, the fibers 22 are mixed at a height H3 only in the lower part. Here, the upper end portion in which the fibers 22 are mixed is located on the excavation surface 18. An H-section steel 30 is inserted into the soil cement column wall 46. The lower portion of the H-shaped steel 30 is embedded in the lower portion in which fibers are mixed. At this time, a stud is provided at the lower part of the H-shaped steel 30, and the lower part of the soil cement column wall 46 and the lower part of the H-shaped steel 30 are firmly fixed.
Thereby, it is possible to reinforce only the fixing portion of the H-section steel 30 that requires a large bending strength. As a result, the bending strength required for the mountain retaining wall 44 can be ensured, and the amount of fibers to be mixed can be reduced.

(Fourth embodiment)
As shown in FIG. 8A, the mountain retaining wall 50 according to the fourth embodiment has a soil cement column wall 56 on an inclined land 52. The soil cement column wall 56 is constructed by wrapping the outer peripheral surfaces of the soil cement columns 12, and reinforcing fibers 22 are mixed therein. Further, the lower end portion of the soil cement column wall 56 is constructed up to below the sliding surface 54.

At this time, the soil cement column wall 56 is constructed on the slope 52 so as to sew the slip surface 54 on which a landslide is predicted.
Thereby, the landslide along the slip surface 54 in the inclined land 52 can be suppressed by the soil cement column wall 56.

  As shown in FIG. 8B, when the area of the sliding surface 54 is large, a plurality of mountain retaining walls 50 (three rows in the figure) may be constructed so as to sew the sliding surface 54. That is, the soil cement column wall 57, 58, 59 in which the reinforcing fibers 22 are mixed is constructed at a predetermined interval. Thereby, the landslide along the slip surface 54 in the inclined land 52 can be suppressed by the soil cement column wall 56.

10 Yamato Wall 12 Soil Cement Column 14 Soil Cement Column Row Wall 18 Drilling Surface 22 Fiber 30 H Shape Steel (Core)
52 Slope 54 Sliding surface

Claims (7)

A soil cement column wall constructed by wrapping the outer peripheral surfaces of the soil cement columns,
Reinforcing fibers mixed inside the soil cement column wall,
Yamatome wall with.   The mountain retaining wall according to claim 1, wherein a core material embedded below the excavation surface is embedded in the soil cement column wall. The soil cement pillar column wall where the outer peripheral surfaces of the soil cement pillars are wrapped, and multiple rows are built on the natural mountain side,
Reinforcing fibers mixed in any row of the soil cement column wall,
A core material embedded in an arbitrary row of the soil cement column wall and embedded below the excavation surface;
Yamatome wall with.   The mountain retaining wall according to any one of claims 1 to 3, wherein the fiber is mixed only in a portion where bending stress acts on the soil cement column wall.   The said fiber is mixed only in the lower part of the said soil cement column wall where the lower part of the said core material is fixed, The stud is provided in the lower part of the said core material. Yamatome wall according to item.   The mountain retaining wall according to any one of claims 1 to 3, wherein the soil cement column wall is constructed on an inclined land so as to sew a slip surface on which a landslide is predicted.   The fiber is a polypropylene fiber whose length ratio to the thickness of the fiber material is adjusted to 1000 or more, and the polypropylene fiber is 0.4 to 2.0% by volume on the soil cement column wall. The mountain retaining wall according to any one of claims 1 to 6, which is mixed within a range.

Images