JP6368158B2 - Seismic reinforcement structure for earth structure, retaining structure, and construction method of improved body - Google Patents

Description

  The present invention relates to a seismic reinforcement structure for earth structures using an improved body, a retaining structure using the improved body, and a method for constructing the improved body.

  The embankment for traffic used as a roadbed is generally constructed more firmly than the embankment for other uses because it is required to reliably support the track and road provided at the top. Nevertheless, the strength is inferior to that of concrete structures, etc., and there is a possibility of collapse due to shaking when a large earthquake occurs. If a collapse occurs while a train or car is passing, it will lead to a serious accident. Therefore, it is required to make the existing embankment earthquake resistant and difficult to collapse.

As a seismic reinforcement method for embankments, conventionally, from the slope of embankments, methods such as driving anchors into the embankments are common. However, when a space for performing seismic reinforcement work cannot be secured on the side of the embankment, for example, a structure is provided on the immediate side of the embankment, work using this method becomes extremely difficult. In particular, the embankments in urban areas where the traffic of trains and cars are relatively large and the seismic reinforcement is urgent are often the case. In recent years, as a seismic reinforcement method that can also be used in such cases, the soil inside the embankment is mixed with a solidifying agent and solidified to form an improved pile extending vertically in the embankment, A technique for increasing the strength of embankment has been proposed (see Non-Patent Document 1).
Moreover, such an improved pile may be used as a retaining wall.

Maki Takayama, Yasuo Watanabe, Kazuhisa Mikami, “Vibration test of model embankment reinforced with improved piles”, Summary of 68th Annual Scientific Lecture Meeting of Japan Society of Civil Engineers, Japan Society of Civil Engineers, September 2013 Month, p. 101-102

A strong earth pressure acts on the improved piles provided on the embankment or the natural ground in the direction from the shoulder to the foot or from the natural ground to the space. Especially during an earthquake, the earth pressure becomes even greater. However, since the improved pile alone does not have sufficient strength, it is necessary to reinforce the strength by arranging the steel material so as to extend in the vertical direction in the improved pile. In addition, in order for the steel material to function as a reinforcing material, it is necessary to fix the steel material to the improved pile with a fixing length of a predetermined value or more. However, improved piles made by solidifying the embankment often have insufficient strength, and it is necessary to ensure a considerable anchorage length in order to firmly fix the steel material. And in order to take much fixing length, you have to form an improved pile deeply in the ground, and the solidification agent and the core material are needed for that much.
In other words, the seismic reinforcement and earth retaining of embankments with improved piles that have been proposed so far have a long construction period and cost.

  The present invention has been made in view of the above problems, and an object of the present invention is to enable construction of a seismic reinforcement structure or earth retaining structure for earth structures using an improved body made of a solidifying agent or the like in a short period of time and at low cost. And

In order to solve the above problems, an invention according to the present application is an earthquake-proof reinforcement structure for an earth structure comprising an earth structure and an improved body provided so as to extend in the vertical direction inside the earth structure. The improved body is formed into a rod shape made of a material having a strength higher than that of the improved pile, the lower part being more than the central axis of the improved pile. A core material that is fixed to the improved pile in a state extending vertically in the site near the top end of the earth structure, and a core member whose upper portion protrudes above the improved pile, and stronger than the improved pile. The fixing member is formed of a high material, has an upper part fixed on the core material, and includes a fixing unit that restricts the relative movement of the core material in the vertical direction .

Here, the earth structure refers to all structures formed of earth and sand, such as embankments, dikes, and cuts.
Moreover, steel, a fiber reinforced plastic (FRP), an organic material, etc. are contained in the material whose strength is higher than the improved pile which forms a core material.
Moreover, mortar, concrete, etc. are contained in the material higher in strength than the improved pile forming the fixing portion.

  Generally, the higher the strength of the material to which the core material is fixed, the shorter the fixing length necessary for fixing the core material. According to the present invention, since the upper part of the core material is fixed to a material having higher strength than the improved pile, the strength of the improved body is not lowered from the conventional improved pile composed only of the improved pile and the core material, and the entire improved body Can be shortened. Therefore, while providing the earth structure with an earthquake resistance comparable to that using the conventional technology, the construction period can be shortened by shortening the improved body, and the required solidifying agent and core material are reduced. So the cost can be reduced.

In the above invention, the fixing portion may be formed of mortar or concrete.
Since general mortar and concrete have a strength 20 times higher than that of an improved pile made of earth and sand and a solidifying agent, in this way, an improved body having a strength comparable to that of a conventional improved pile can be shortened. Can be formed. Therefore, the construction period can be further shortened and the cost can be reduced.

Further, another invention according to the present application is a soil retaining structure having an underground continuous wall formed by arranging a plurality of improved bodies extending in the vertical direction in the horizontal direction along the side surface of the natural ground. At least a part of the plurality of improved bodies is formed into a rod-like shape with an improved pile obtained by solidifying a mixture containing at least earth and sand and a solidifying agent, and a material higher in strength than the improved pile, and the lower part is the center of the improved pile A core material fixed to the improved pile in a state of being arranged to extend in a vertical direction in a portion closer to the top end of the earth structure than the shaft, and a core member whose upper portion protrudes above the improved pile; and the improved pile It is made of a material having higher strength than the above, and includes a fixing portion that fixes the upper portion of the core material and restricts the relative movement of the core material in the vertical direction .

  According to the invention, since the upper part of the core material is fixed to a material having higher strength than the improved pile, the improved body as a whole can be obtained without dropping the strength of the improved body from the conventional improved pile composed only of the improved pile and the core material. Can be shortened. Therefore, while sufficiently suppressing the collapse of the natural ground, the construction period is shortened by shortening the improved pile, and the necessary solidifying agent and core material are reduced, so that the cost can be suppressed.

Further, according to another invention of the present application, there is provided a method for constructing an improved body in which an improved body is provided so as to extend in a vertical direction inside the earth structure or the ground, and is solidified inside the earth structure or the ground. An improved pile that becomes a lower part of the improved body by injecting an agent, mixing with the earth and sand of the earth structure or the earth and sand of the natural structure, and solidifying the mixture formed by mixing the solidifying agent and the earth and sand A core material formed in a rod shape with a material higher in strength than the improved pile in a portion closer to the top end of the earth structure than the central axis of the improved pile, and a lower portion of the improved pile. It extends vertically inside, and is inserted so that the upper part protrudes above the improved pile, and the lower part is fixed to the improved pile, and the upper part of the core material is stronger than the improved pile. high material, the fixing part serving as the upper of the improved body, fixed to the core material, prior It characterized that you formed so as to restrict the relative movement vertically in the core material.

  According to the invention, since the upper part of the core material is fixed to a material having higher strength than the improved pile, the improved body as a whole can be obtained without dropping the strength of the improved body from the conventional improved pile composed only of the improved pile and the core material. Can be shortened. Therefore, while demonstrating the required seismic performance or earth retaining performance, the construction period can be shortened by the amount that the formation start position of the improved pile can be made shallower, and the cost can be reduced because fewer solidifying agents and core materials are used. .

In the above invention, excavating the earth and sand above the core material, forming a space around the upper portion of the core material, pouring mortar or concrete into the space to solidify the core material, You may make it fix to mortar or the said concrete.
In this way, the embankment around the space or the embankment of the embankment replaces the formwork, so that the fixing portion can be formed simply by pouring and solidifying the mortar or concrete, and the construction becomes easy.

Moreover, in the said invention, when the object which provides the said improvement body is the said earth structure, and the natural ground under the said earth structure is what is easy to express intensity | strength by improvement, inside the said natural ground The lower part of the improved pile may be formed, and then the upper part of the improved pile may be formed inside the earth structure above the lower part of the improved pile.
In this way, the strength of the lower part of the improved body is increased, and the overall length of the improved body is reduced without dropping from the improved pile formed by improving the earth and sand that is difficult to express the strength even if the improved body is improved. Can be shortened.

Moreover, in the said invention, you may make it fix the lower end part of the said core material to the lower part of the said improved pile.
If it does in this way, since the lower part of a core material will settle in a site | part with high intensity | strength, the length of the whole improvement pile can be shortened further.

In the above invention, after the improved pile is formed, a hole extending in the vertical direction is drilled in the improved pile, the core material is inserted into the hole, and the gap between the improved pile and the core material is initially May have a fluidity and may be solidified by being filled with a filler that has higher strength than the improved pile after curing.
If it does in this way, even if it is a case where it is difficult to insert a core material in the mixture of the earth and sand which has not yet solidified, and a solidifying agent, a core material can be fixed to an improvement pile.

  ADVANTAGE OF THE INVENTION According to this invention, the earthquake-proof reinforcement structure or earth retaining structure of the earth structure using the improved pile which consists of a solidifying agent etc. can be constructed | assembled for a short period of time and low cost.

It is a vertical sectional view of the earthquake-proof reinforcement structure for earth structure according to the first embodiment of the first invention. It is II-II sectional drawing of FIG. It is a figure which shows 1 process of the seismic reinforcement method of the earth structure which concerns on the embodiment. It is a figure which shows the process after the process of FIG. It is a figure which shows the process after the process of FIG. It is a vertical sectional view of a seismic reinforcement structure for earth structures according to a second embodiment of the present invention. It is a figure which shows the process after the process of FIG. It is a figure which shows 1 process of the seismic reinforcement method of the earth structure which concerns on the embodiment. It is a figure which shows the process after the process of FIG. It is a vertical sectional view of a seismic reinforcement structure for earth structures according to a third embodiment of the present invention. (A) is a perspective view of the earth retaining structure which concerns on embodiment of 2nd invention, (b) is bb sectional drawing of (a).

<First Embodiment of the First Invention>
Hereinafter, a first embodiment of the first invention will be described in detail with reference to FIGS.

[Seismic reinforcement structure for earth structures]
First, the seismic reinforcement structure of the earth structure will be described using an embankment as an example. FIG. 1 is a vertical sectional view of a seismic reinforcement structure 10 for embankment according to the present embodiment, and FIG. 2 is a sectional view taken along line II-II in FIG.
The embankment seismic reinforcement structure 10 increases the strength of the embankment 1 by the retaining wall 2 provided on the slope 12 of the embankment 1 and the plurality of improved bodies 3 provided from the slope to the inside of the embankment 1. It has become. Moreover, the structure St is provided on the side of the embankment 1 without being spaced from the embankment 1, and a space cannot be secured on the side of the slope 12 of the embankment 1.

The embankment 1 is continuously built along the direction orthogonal to the paper surface of FIG. The cross-sectional shape when the embankment 1 is cut along a plane orthogonal to the building direction is substantially trapezoidal (in FIG. 1, only the vicinity of the slope on one side is shown). The top end 11 is horizontal, and above it, a track and a road (not shown) are provided along the direction in which the embankment 1 continues. The upper part of the slope 12 (hereinafter referred to as the upper slope 12a) has a predetermined slope, and the lower part of the slope 12 (hereinafter referred to as the lower slope 12b) is less than the upper slope 12a due to the site restrictions due to the structure St. Even the slope is steep.
In the embankment 1 constructed in such a shape, when the reinforcement is not sufficient, the earth and sand on the side portions are liable to collapse on the side of an arcuate curved surface (hereinafter referred to as a slip surface) as shown by P in the figure. It is known. In addition, the sliding surface P of a figure has shown what is assumed on calculation when the embankment 1 is reinforced only by the retaining wall 2, and in the embankment 1 of a shape like this embodiment, the center part of the top end 11 is shown. In general, it spreads from the vicinity to the outer edge 14.

  The retaining wall 2 is formed so as to cover the entire lower slope 12b. The retaining wall 2 is inclined in parallel with the lower slope 12b when viewed from the direction shown in FIG. It is designed to resist 1 earth pressure.

A plurality of the improved bodies 3 are installed along the continuous direction of the embankment 1 so as to be arranged at a predetermined interval. Each improvement body 3 is provided so that the slip surface P assumed may be penetrated, and the intensity | strength of the embankment 1 in the slide surface P vicinity is raised.
Each improved body 3 includes an improved pile 31 provided in the embankment 1, a core 32 arranged so as to penetrate the improved pile 31 in the vertical direction, and an upper portion protruding above the improved pile 31, and the improved pile The fixing unit 33 is provided above 31 and around the upper portion of the core member 32.

  The improved pile 31 is solidified in a state where a solidifying agent such as cement slurry and the same sediment as the embankment 1 are mixed, and is formed in a columnar shape extending in the vertical direction below the upper slope 12a. Has been. Moreover, the improved pile 31 is formed so that the sliding surface P mentioned above may be penetrated up and down, and the lower part may reach the natural ground G under the embankment 1. An anchor 311 is driven into the upper surface of the improved pile 31.

  The core material 32 is made of a rod material made of steel (including shape steel), FRP or the like having a higher strength than the improved pile 31, and the top end 11 of the cylindrical improved pile 31 is higher than the central axis C. One or a plurality of pieces (FIG. 2 shows a plurality of pieces) extending in the vertical direction in the part closer to the side and having the lower end thereof reaching below the sliding surface P or the boundary surface B between the embankment 1 and the natural ground G. Case) is arranged. The lower part of the core material 32 is fixed to the improved pile 31, the upper part protrudes upward from the upper surface of the improved pile 31, and the upper end part is bent sideways. In addition, when using two or more core materials 32 with respect to the one improvement pile 31, when it sees in parallel mutually and from upper direction, as shown in FIG. It is preferable to arrange it along the side surface.

  The fixing portion 33 is made of mortar or concrete (in some cases, a reinforcing bar may be used in combination), is provided above the improved pile 31, and is fixed to the core member 32 protruding upward from the improved pile 31. That is, the upper part of the core member 32 is fixed to the fixing unit 33. In addition, the fixing unit 33 is also fixed to the anchor 311 of the improved pile 31, thereby improving the integrity of the improved pile 31 and the fixing unit 33. When a plurality of core members 32 are used for one improved pile 31, fixing portions 33 may be formed at the upper end portion of each core member 32, or a plurality of fixing members 33 may be formed in one fixing portion 33. The upper end portion of the core member 32 may be fixed.

  In general, the fixing length of the core material 32 depends on the strength of the material to be fixed. That is, the higher the strength of the material to which the core material 32 is fixed, the shorter the fixing length. For this reason, when fixing the whole core material 32 to the improvement pile 31 by fixing a part of the core material 32 to the mortar or concrete (fixing part) whose strength is higher than the improvement pile 31 like this embodiment. Compared with, the overall length of the improved body 3 can be shortened without reducing the strength of the improved body 3. Accordingly, while the embankment 1 has an earthquake resistance comparable to that of the conventional technique, the construction period is shortened by shortening the improved body 3, and the necessary solidifying agent g and core material 32 are provided. Since it decreases, the embankment 1 required for the embankment 1 can be provided with the earthquake resistance at low cost.

[Seismic reinforcement method for earth structures]
Next, a method for forming the embankment 1 as described above will be described.
The method for reinforcing the embankment 1 of the present embodiment includes an improved body formation / core material arranging step and a fixing portion forming step.

(Improvement body formation and core material installation process)
In the first improved body formation / core material installation step, first, as shown in FIG. 3, the working scaffold Sc is constructed on the upper slope 12a, and the equipment M1 for forming the improved pile 31 is provided thereabove. Install. Then, an improved pile 31 is formed in the embankment 1. In this embodiment, it forms, for example using a high pressure injection stirring method. Specifically, first, the high-pressure solidifying agent g is sprayed onto the natural ground G from the injection port at the lower end of the equipment M1, and the earth and sand 3a and the solidifying agent g are removed. Mix. Thereafter, the solidifying agent g is jetted and the earth and sand 3a of the embankment 1 is stirred while moving the jet port upward.

  After mixing the earth and sand 3a in a predetermined range with the solidifying agent g, as shown in FIG. 4, the equipment M1 used for forming the improved pile 31 is removed from the scaffold Sc, and the earth and sand 3a that has not yet solidified is solidified. The core material 32 is pushed into the mixture with the agent g from the upper slope 12a into the lower end of the mixture. As a method of pushing in, one long core material 32 may be pushed in, or the core material 32 is divided into a plurality of short bars, and one of the bars is pushed in, and the upper end of the core material 32 is pushed into the upper end. You may make it repeat the operation | work of adding and pushing in the next bar. When a plurality of core members 32 are used for one improved pile, the plurality of core members 32 are sequentially pushed in while shifting the position to the side. When the mixture of the earth and sand 3a and the solidifying agent g is solidified, the improved pile 31 is formed, and the core material 32 is fixed to the improved pile 31.

(Fixing part forming process)
After fixing the core material 32 to the improved pile 31, the process proceeds to the fixing portion forming step. In the fixing portion forming step, first, the earth and sand around the upper portion of the core material 32 is excavated until the upper surface of the improved pile 31 is exposed. The excavation is performed while forming a cylindrical retaining wall 33a around the core member 32 as shown in FIG. Thereafter, the upper end of the core member 32 is bent sideways, the anchor 311 is driven into the upper surface of the improved pile 31, and a reinforcing bar (not shown) is assembled in the inner space S1 of the earth retaining wall 33a. Then, concrete or mortar is poured into the inner space S1 of the retaining wall 33a. By doing so, the retaining wall 33a can be used instead of the formwork, so that the work of pouring mortar or concrete is facilitated. When the poured concrete or mortar is solidified, the fixing portion 33 shown in FIG. 1 is formed, and the upper portion of the core member 32 is fixed to the fixing portion 33. In this way, one improvement body 3 is built inside the embankment 1. Note that the step with the upper slope 12a formed after the fixing portion 33 is formed may be left as it is or may be backfilled.

  Thereafter, by repeating the above-described improved body formation / core material installation step and fixing portion formation step a plurality of times while shifting the position where the scaffold Sc is assembled by a predetermined distance in the continuous direction of the embankment 1, A plurality of improved bodies 3 are provided so as to be arranged along the continuous direction of the embankment 1, and the embankment earthquake-proof reinforcement structure 10 of the present embodiment is completed.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to FIGS. Here, only differences from the first embodiment will be described, and description of similar points will be omitted.

[Seismic reinforcement structure for earth structures]
First, a seismic reinforcement structure for a soil structure will be described using an embankment as an example in the present embodiment. FIG. 6 is a vertical cross-sectional view of the embankment seismic reinforcement structure 10A according to the present embodiment.
The embankment earthquake-proof reinforcement structure 10A of the present embodiment is different from the first embodiment in the configuration of the improved pile.

The improved body 3 </ b> A of the present embodiment is such that the embedded material 34 is filled between the improved pile 31 and the core material 32.
The embedding material 34 is obtained by solidifying a material that can ensure material inseparability while having high fluidity and filling properties, such as cement milk and mortar, and the like that forms the fixing portion 33. It is fixed to the improved pile 31 and the core material 32. That is, the lower part of the core material 32 of the present embodiment is fixed to the improved pile 31 via the embedded material 34.

[Seismic reinforcement method for earth structures]
Next, the method of making the embankment 1 into the above-described seismic reinforcement structure 10A will be described. The embankment seismic reinforcement method of the present embodiment is different from the first embodiment in that the core material is installed after the improved body is formed. Different.

(Improvement process)
In the present embodiment, first, as in the first embodiment, the solidifying agent g is jetted and stirred with the earth and sand 3a while moving the jetting port upward. After the earth and sand 3a in a predetermined range is mixed with the solidifying agent g, the mixture of the earth and sand 3a and the solidifying agent g is solidified as it is without inserting the core material 32 to form the improved pile 31.

(Core material installation process)
After forming the improved pile 31 in the embankment 1, it moves to a core material installation process. In the core material forming step, first, the equipment M1 used for forming the improved pile 31 is removed from the scaffold Sc, and the earth and sand around the upper portion of the core material 32 is excavated until the upper surface of the improved pile 31 is exposed. Excavation is performed while forming a cylindrical retaining wall 33a around the core member 32 as shown in FIG. And the drilling machine M2 is installed in scaffold Sc. Then, the improved pile 31 is drilled vertically downward from a location closer to the top end 11 than the center axis C on the upper surface of the improved pile 31 by the punching machine M2, thereby forming the insertion hole 31b. The insertion hole 31b is formed so as to have a perforation depth corresponding to the strength to be provided (a fixing length can be secured) in a range that does not penetrate the improved pile 31 (the bottom of the insertion hole 31b is formed in the improved pile 31). . Thereafter, as shown in FIG. 8, the core member 32 is inserted into the insertion hole 31b until the lower end reaches the bottom of the insertion hole 31b. Then, cement milk or mortar is filled in the gap between the core material 32 and the insertion hole 31b. When the cement milk or mortar is solidified, an embedding material 34 is formed, and the core material 32 is fixed to the improved pile 31 via the embedding material 34 as shown in FIG.

<Third Embodiment>
Next, a third embodiment of the present invention will be described with reference to FIG. Here, only differences from the first embodiment will be described, and description of similar points will be omitted.

[Seismic reinforcement structure for earth structures]
First, a seismic reinforcement structure for a soil structure will be described using an embankment as an example in the present embodiment. FIG. 9 is a vertical sectional view of the embankment seismic reinforcement structure 10B according to the present embodiment.
The embankment seismic reinforcement structure 10B of the present embodiment is different from the first embodiment in that the target embankment and soil soil quality are limited, and the structure of the improved pile.

  The natural ground Gb under the embankment 1b of this embodiment has a high-quality soil that is easier to improve than the embankment 1b. Specifically, when the natural ground Gb is sandy soil and the embankment 1b is viscous soil or sandy soil containing viscous soil, or the natural ground Gb is sandy soil including viscous soil, and the embankment 1b is In the case of clay soil, the ratio of the sandy soil in the natural ground Gb is higher than that of the embankment 1b.

  In the improved pile 3B of the present embodiment, the strength of the lower portion of the improved body 31, more specifically, the portion provided inside the natural ground Gb is higher than the upper portion provided inside the embankment 1b. Hereinafter, the lower part (part having higher strength than the upper part) of the improved body 31 is referred to as a lower fixing part 31a. Further, the lower end portion of the core member 32 is fixed to the lower fixing portion 31a. For this reason, the improved pile 3A has a strength comparable to that of the first embodiment, but is shorter than that of the first embodiment (the lower end is shallower). Accordingly, the construction period is shortened by that amount, and the necessary solidifying agent g and core material 32 are reduced. Therefore, an embankment earthquake-proof reinforcement structure 10B having an earthquake resistance comparable to that of the conventional construction is constructed at a low cost. Can do.

[Seismic reinforcement method for earth structures]
Next, a method of using the embankment 1 as the above-described seismic reinforcement structure 10B will be described.
The embankment seismic reinforcement method of the present embodiment is different from the first embodiment in the flow of the improved body forming process.

(Improvement process)
In the improved body formation process of this embodiment, formation of the improved body is started from a position below the boundary surface B and shallower than the start position of the improved body formation process in the first embodiment. And the formation of the improved body from the starting position to the boundary surface B is performed by using a solidifying agent having a higher concentration than the solidifying agent used in the improved body forming step of the first embodiment or a solidifying agent having a high solidification performance. Alternatively, it is formed by increasing the injection amount of the solidifying agent g per unit volume of the earth and sand 3a than in the first embodiment. The higher the percentage of sandy soil contained in the earth and sand, the easier it is to increase the strength by changing various conditions such as solidifying agents and construction methods. In the natural ground Gb having a high ratio, the lower fixing portion 31a having a higher strength than the improved body 31 is formed. On the other hand, even if the sand with a relatively low proportion of sandy soil forming the embankment 1b is improved under the same condition as the earth and sand Gb, the strength cannot be expected so much. The upper part of the improved body 31 after forming the part 31a is formed in the same manner as in the first embodiment.

In this way, the strength of the lower portion (lower fixing portion 31a) of the improved body 31 is higher than the upper portion of the improved body 31, so that the entire structure including the lower portion is made the same as the upper portion without damaging the strength of the improved pile 3B. The length in the vertical direction can be made shorter than that of the improved pile composed only of the formed improved body 31 and the core material 32. Accordingly, the construction period is shortened by the amount by which the formation start position of the improved body 31 can be shallow, and the cost of the solidification agent g and the core material 32 to be used can be reduced.
In particular, railway embankments that support tracks in the Tokyo metropolitan area are often built under the soil conditions as in this embodiment, so there are many cases where the lower fixing portion 31a is provided as in this embodiment. It is effective for earthquake-proof reinforcement of the embankment in a short period.

<Second Invention Embodiment>
Next, an embodiment of the second invention will be described with reference to FIG. Here, only differences from the first embodiment of the first invention will be described, and description of similar points will be omitted.
The first invention is a seismic reinforcement structure for earth structures using the improved body 3, but the second invention is a earth retaining structure using the improved body 3.

[Retaining structure]
First, the earth retaining structure will be described. FIG. 10A is a perspective view of the earth retaining structure 10C according to the present embodiment, and FIG. 10B is a cross-sectional view taken along line bb of FIG. 10A.
The earth retaining structure 10 </ b> C is, for example, a structure in which both side surfaces of a space S <b> 2 formed in a natural ground are earthed by a pair of underground continuous walls 4.

The continuous walls 4 in each place are formed as one wall body by providing a plurality of the improved bodies 3 adjacent to each other in the horizontal direction. The structure of each improvement body 3 is the same as that of the improvement body 3 used in 1st Embodiment.
The fixing unit 33 may be provided for each improved body 3 or may be formed so as to extend long in the arranging direction of the improved bodies 3 so that a plurality of core members 32 can be fixed together. Good.
The lower part of each improvement body 3 is located below the bottom face of the space S2, and is embedded in the natural ground G.

[Dwelling method]
Next, a method for constructing the earth retaining structure as described above will be described.
First, the some improvement body 3 is formed in the side of the location which is going to form the space S2 of the natural ground G. FIG. The method of forming the individual improved bodies 3 is almost the same as that of the first embodiment. However, as shown in FIG. 10B, when the work location of the natural ground G is horizontal, the work platform is constructed. Can be omitted.
The improvement bodies 3 may be formed sequentially so as to be next to the formed improvement piles, or in order to form without any gaps, each improvement body 3 is slightly smaller than the width of one improvement pile. After forming at a short interval, a new improvement body 3 may be formed between the improvement body 3 and the improvement body 3 so as to be partially integrated with the improvement body of the existing improvement body 3. In addition, as shown to Fig.10 (a), when forming the fixing | fixed part 33 so that it may extend long in the row direction of the some improvement body 3, only the improvement pile 31 and the core material 32 are incomplete improvement previously. After constructing a plurality of piles, the fixing portion 33C is finally formed.

  After constructing the pair of underground continuous walls 4 so as to be parallel to each other, the soil between them is excavated. When the earth and sand are excavated to a predetermined depth, a space S <b> 2 is formed between the pair of underground continuous walls 4, and a natural ground G on the side of the space S <b> 2 is retained by the underground continuous wall 4.

As mentioned above, although the invention based on this application was concretely demonstrated based on embodiment, this invention is not limited to the said embodiment, It can change in the range which does not deviate from the summary.
For example, in the first to third embodiments of the first invention, embankment is taken as an example, but the present invention can also be applied to other earth structures such as cuts and dikes.
In the first to third embodiments, the embankment in which a part of the slope is protected by the retaining wall is taken as an example, but the present invention can also be applied to an earth structure having no retaining wall.
Moreover, in 1st-3rd embodiment, although the some improvement pile was formed so that the space | interval might be spaced apart, it is good also as a wall body by making a some improvement pile adjoin like the underground continuous wall of 2nd invention.
Further, in the third embodiment and the second embodiment of the first invention, the improved pile is the core material fixed directly to the improved body, but, as in the second embodiment, the embedded pile is interposed. It is also possible to fix it.
In the first embodiment, the space for forming the fixing portion is formed after the core material is embedded, but before the mixing of the earth and sand and the solidifying agent is started, or after the earth and sand and the solidifying agent are mixed. You may make it form before embedding a core material.
In the above embodiment, the fixing force is increased by bending the upper end portion of the core member 32 to the side. However, a fixing plate is attached to the upper end portion, or a fixing plate or a retaining wall support portion is used by using a joint. It may be integrated with the reinforcing bar.
Moreover, in the said embodiment, although the improved body was formed by the high pressure injection stirring method, what is necessary is just a method which can form the improvement body by the earth and sand 3a and the solidifying agent g, such as a mechanical stirring method and a high pressure injection combined use type mechanical stirring method. .
Moreover, in the said embodiment, although the anchor 311 which connects the improved pile 31 and the fixing | fixed part 33 was driven after solidification of the improved pile 31, the anchor 311 is arrange | positioned during formation of the improved pile 31 (before solidifying). In addition, it may be fixed at the time of solidification.

10, 10A, 10B Embankment seismic reinforcement structure (earth structure seismic reinforcement structure)
10C Earth retaining structure 1, 1b Embankment (earth structure)
11 Top edge 12 Slope 12a Upper slope 12b Lower slope 13 Shoulder 14 Leg 2 Retaining wall 3, 3A, 3B Improved body 3a Earth and sand 31 Improved pile 31a Lower anchorage (lower part of improved pile)
31b Insertion hole 311 Anchor 32 Core material 33 Fixing part 33a Earth retaining wall 34 Embedding material (material having higher strength than improved pile)
4 Underground continuous wall B Boundary surface C Center axis G, Gb Ground mountain g Solidifying agent M1 Equipment M2 Drilling machine P Sliding surface S1, S2 Space Sc Scaffolding St Structure

Claims (8)

An earthquake-proof reinforcement structure for an earth structure comprising an earth structure and an improved body provided so as to extend in the vertical direction inside the earth structure,
The improved body is:
An improved pile made by solidifying a mixture containing at least earth and sand and a solidifying agent;
The improved pile is formed in a rod shape with a strength higher than that of the improved pile, and the lower portion is arranged so as to extend in a vertical direction in a portion closer to the top end of the earth structure than the central axis of the improved pile. A core material fixed to the pile, and the upper part protruding above the improved pile;
Seismic reinforcement structure for earth structure, characterized in that it is formed of a material having strength higher than that of the improved pile, the upper portion of the core material is fixed, and a fixing portion for restricting relative movement in the vertical direction of the core material is provided. .   The seismic reinforcement structure for earth structure according to claim 1, wherein the fixing portion is formed of mortar or concrete. A soil retaining structure having an underground continuous wall formed by arranging a plurality of improved bodies extending in the vertical direction in the horizontal direction along the side surface of the natural ground,
At least some of the plurality of improvements are
An improved pile made by solidifying a mixture containing at least earth and sand and a solidifying agent;
The improved pile is formed in a rod shape with a strength higher than that of the improved pile, and the lower portion is arranged so as to extend in a vertical direction in a portion closer to the top end of the earth structure than the central axis of the improved pile. A core material fixed to the pile, and the upper part protruding above the improved pile;
An earth retaining structure , comprising a fixing portion that is formed of a material having a strength higher than that of the improved pile, the upper portion of the core material is fixed, and the vertical movement of the core material is restricted . In the construction method of the improved body provided in the earth structure or the natural ground so that the improved body extends in the vertical direction,
Injecting a solidifying agent into the earth structure or ground and mixing it with the earth and sand of the earth structure or ground, and solidifying the mixture formed by mixing the solidifying agent and the earth and sand. By forming an improved pile that becomes the lower part of the improved body,
In the part closer to the top end of the earth structure than the central axis of the improved pile, a core formed in a rod shape with a material stronger than the improved pile, the lower part is in the vertical direction inside the improved pile And the upper part protrudes above the improved pile, and the lower part is fixed to the improved pile.
Around the upper part of the core material, a fixing part that is an upper part of the improved body is fixed with the core material with a material stronger than the improved pile, and the relative movement in the vertical direction of the core material is restricted. forming to a method for constructing an improved body, characterized in Rukoto as. Excavating the earth and sand above the core material, forming a space around the upper portion of the core material,
The construction method of the improved body according to claim 4, wherein the core material is fixed to the mortar or the concrete by pouring mortar or concrete into the space and solidifying the mortar or concrete. When the object to be provided with the improved body is the earth structure, and the natural ground below the earth structure is easy to express strength by improvement,
Form the lower part of the improved pile inside the natural ground,
6. The method for constructing an improved body according to claim 4 or 5, wherein the upper portion of the improved pile is formed inside a soil structure above the lower portion of the improved pile.   The construction method of the improved body according to claim 6, wherein a lower end portion of the core material is fixed to a lower portion of the improved pile. After forming the improved pile, drill a hole extending vertically in the improved pile,
Insert the core material into the hole,
8. The gap between the improved pile and the core material is filled with a filler that initially has fluidity and is harder than the improved pile after hardening, and is solidified. The construction method of the improvement body as described in any one of these.

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