JP2016204959A - Construction method of underground base-isolation wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction method of an underground base-isolation wall capable of constructing in an original position the underground base-isolation wall provided by filling an underground hole of a column row shape with a clay-based material having water absorptive expandability.SOLUTION: A method for constructing a continuous wall-shaped underground base-isolation wall by filling an underground hole 12 of a column row shape excavated-formed in the ground with a clay-based material having water absorptive expandability, constructs the underground base-isolation wall by repeating a process of discharging excavation soil 20 on the ground by excavating-forming the underground hole 12 by an auger 10 and a process of substituting-filling one underground hole 12 with-by the clay-based material having the water absorptive expandability by injecting-filling slurry S of predetermined density composed of the clay-based material having the water absorptive expandability into a space of the underground hole 12 from the tip of the auger 10 by sending to the tip of the auger 10 via a hollow pipe 18 installed in the auger central axis, on the respective underground holes 12 formed in the column row shape.SELECTED DRAWING: Figure 1-3

Description

  The present invention relates to a method for constructing underground seismic isolation walls constituting a ground displacement absorbing base isolation structure for reducing stress on underground structures such as open tunnels during earthquakes.

  2. Description of the Related Art Conventionally, a ground displacement absorbing base isolation structure for reducing stress during an earthquake on an underground structure such as an open tunnel is known (see, for example, Patent Document 1 or 2). FIG. 5 is a schematic cross-sectional perspective view of the ground displacement absorbing base isolation structure of Patent Document 1. As shown in this figure, when the underground seismic isolation wall 3 is provided along the underground structure 2 embedded in the surrounding ground 1, it is sufficient for the earth pressure acting on the underground seismic isolation wall 3. While it is a material that can withstand long-term stability, it is desirable that the material has low rigidity in order to exhibit the seismic isolation effect. Is required.

  The above-mentioned Patent Document 1 has been made in view of the above-described problems, and can secure the long-term stability of the underground seismic isolation wall and reduce stress on underground structures such as an open tunnel during an earthquake. A ground displacement absorbing seismic isolation structure that can be used is realized by the following measures (1) to (4).

(1) As shown in FIG. 5, between the surrounding ground 1 and the structure 2, a continuous wall-shaped seismic isolation layer 3 (underground wall or underground seismic isolation wall) made of water-absorbing and swelling clay-based material. Is installed.
(2) As a clay-based material constituting the underground wall, a mixture of bentonite and water, or a mixture of bentonite and aggregate (soil material such as gravel or artificial material that is difficult to change for a long time such as glass beads) and water is used. .
(3) The region filled with a material composed of a mixture of bentonite and water in the clay-based material constituting the underground wall is characterized by having a bentonite dry density value in a range of 300 to 1200 kg / m ^3. .
(4) In a material composed of a mixture of bentonite, aggregate and water, which is a clay-based material constituting the underground wall, an area filled with bentonite and water (bentonite and water filling the area excluding the aggregate area) In the range of 300 to 1200 kg / m ³ in terms of bentonite dry density.

  On the other hand, the underground wall construction method disclosed in Patent Document 2 is not limited to a material containing 100% bentonite, but a bentonite material adjusted to have a predetermined bentonite effective dry density, or a mixture of bentonite and aggregate. A process of filling a bag with a material filled with a bag.

  By the way, said patent document 1 uses the water-absorbing expansive clay (for example, bentonite) which exhibits the swelling pressure (water absorption expansion pressure) which can oppose earth pressure, although it is a continuous underground wall, There was a feature in maintaining the structural form. On the other hand, in order to improve the seismic isolation effect, it is desirable to use a material having a smaller shear rigidity (in other characteristics, a low transverse wave velocity Vs) as the underground wall material.

  When constructing the underground seismic isolation wall 3 as shown in FIG. 5 with a material having a low shear rigidity, a continuous groove-shaped excavation space is formed in the ground, and the space is filled with a material having a low shear rigidity. The construction method is applicable. Further, instead of such a method, for example, as shown in FIGS. 6 and 7, a plurality of cylindrical underground holes 4 are excavated in a column shape and filled with water-absorbing expansive clay (for example, bentonite). You may build with.

On the other hand, according to Non-Patent Document 1, as shown in FIG. 8, the smaller the ratio (Vs ratio) of the shear wave velocity Vs of the underground wall (base isolation wall) material to the shear wave velocity of the surrounding ground is, Since the reduction rate (after / before) of the shear force of (structure) is reduced, the seismic isolation effect is large. Further, according to Non-Patent Document 2, it is desirable that the construction density of bentonite is about 0.4 to 1.0 g / cm ³ in terms of dry density as shown in the graph of FIG.

  Such low-density water-absorbing expansive clay (for example, bentonite) has the property of not shrinking the volume when subjected to external pressure, and has rigidity against volume deformation, but has poor bending rigidity and shear rigidity. It is difficult to construct this in advance and then insert it into the columnar underground hole. For this reason, it is required to construct in situ immediately after excavating the underground hole.

JP 2012-031662 A JP 2012-031663 A

Zhang Zhiyue, Fukutake Yasuyoshi et al., “Examination of seismic isolation wall structure of underground structure using bentonite (Part 2: Consideration of seismic isolation effect by FEM analysis)”, Japan Society of Civil Engineers 65th Annual Lecture, Heisei September 22 Yoichi Taji, Toshiyoshi Fukutake et al., “Examination of ground-displacement seismic isolation wall structure using bentonite -Evaluation of shear wave velocity of bentonite specimen-”, 68th Annual Conference of Japan Society of Civil Engineers September 2013

  This invention is made in view of the above, Comprising: An underground seismic isolation wall obtained by filling a columnar underground hole with a clay-based material having water-absorbing expansibility is constructed in situ. The purpose is to provide a construction method for underground seismic isolation walls.

  In order to solve the above-described problems and achieve the object, the construction method of the underground seismic isolation wall according to the present invention is a clay-based material having a water-absorbing expansibility in a columnar underground hole excavated in the ground. This is a method of constructing a continuous wall-shaped underground seismic isolation wall by filling it with an auger, excavating and forming an underground hole, and discharging the excavated soil to the ground, and attaching it to the auger central axis One underground hole is formed by sending a slurry of a predetermined density made of a clay-based material having water-absorbing expansibility from the ground to the tip of the auger through the hollow tube, and injecting and filling the space from the tip of the auger into the space of the underground hole. It is characterized in that a seismic isolation wall is constructed by repeating the step of substituting and filling with a clay-based material having water-absorbing expansibility for each central hole in a columnar shape.

  In addition, another underground seismic isolation wall construction method according to the present invention is a continuous wall-like structure in which a columnar underground hole excavated in the ground is filled with a clay-based material having water-absorbing expansibility. A method for constructing a seismic isolation wall in the ground, in which a drilling device excavates the ground in the planned drilling area and discharges the excavated soil to the ground, and protects the hole wall of the underground hole The step of inserting a casing pipe with the progress of excavation is repeated to form an excavation of an underground hole whose hole wall is protected by the casing pipe, and then the water-absorbing expansibility from the ground via the hollow pipe A step of filling and filling one underground hole with a clay-based material having water-absorbing expansibility by injecting and filling a slurry of a predetermined density made of a clay-based material having a water content into the casing tube and then removing the casing tube; Repeat for each hole in the column. Characterized in that it build a Chumen Shinkabe.

  Moreover, the construction method of another underground seismic isolation wall according to the present invention is the above-described invention, in which the porous tube is inserted into the central shaft portion of the underground hole that is replaced and filled with the clay-based material having water-absorbing expansibility, The porous tube is characterized by pouring water having an electrolyte concentration lower than pore water in the surrounding ground.

  Moreover, the construction method of another underground seismic isolation wall according to the present invention is characterized in that, in the above-described invention, the slurry to be injected and filled is a mixed material of ethanol water or salt water and bentonite.

  Moreover, the construction method of another underground seismic isolation wall according to the present invention is characterized in that, in the above-described invention, the slurry to be injected and filled is a mixed material of ethanol water or salt water, bentonite and aggregate.

  In addition, in the above-described invention, the construction method of the underground seismic isolation wall according to the present invention is the bentonite content per unit volume of the slurry to be injected and filled, wherein the clay-based material having water-absorbing expandability is a bentonite-based material. Is increased according to the depth of the underground hole.

  In addition, another underground seismic isolation wall construction method according to the present invention is a continuous wall-like structure in which a columnar underground hole excavated in the ground is filled with a clay-based material having water-absorbing expansibility. A method for constructing a seismic isolation wall in the ground, in which a drilling device excavates the ground in the planned drilling area and discharges the excavated soil to the ground, and protects the hole wall of the underground hole And a step of excavating and forming an underground hole in which a hole wall is protected by the casing tube by repeating the step of inserting the casing tube with the progress of excavation, and thereafter, a clay having a water-absorbing expansive property partially or entirely in advance. By inserting the water-impervious bag filled with the system material into the casing tube and then removing the casing tube, one underground hole is loaded into the water-impervious bag blocked from the surrounding groundwater Substitution filling with clay-based material with excellent water absorption That the process, characterized by constructing the underground MenShinkabe is repeated for all over the pores forming the pillar rows.

  In addition, in the above-described invention, the construction method of the underground seismic isolation wall according to the present invention is such that the clay-based material loaded in the water-impervious bag is a mixed material of ethanol water or salt water, bentonite, and aggregate. It is characterized by.

  According to the construction method of an underground seismic isolation wall according to the present invention, a continuous wall-shaped ground is formed by filling a columnar underground hole excavated in the ground with a clay-based material having water-absorbing expansibility. This is a method of constructing a middle seismic isolation wall, in which a hole is excavated and formed by an auger, and the excavated soil is discharged to the ground, and a water absorption expansion is performed from the ground via a hollow tube attached to the central axis of the auger. A slurry of a specific density made of clay-based material is sent to the tip of the auger and injected into the space of the underground hole from the auger tip to replace and fill one underground hole with a clay-based material having water-absorbing expansibility This process is repeated for each central hole in the columnar shape to construct a seismic isolation wall, eliminating the possibility of collapse of the inner wall of the columnar underground hole. Underground obtained by filling clay holes with water-absorbing expansibility into the borehole The Shinkabe an effect that can be relatively easily be constructed in situ using auger and hollow tubes.

  In addition, according to the construction method of the other underground seismic isolation wall according to the present invention, the columnar underground holes excavated in the ground are continuously filled with a clay-based material having water-absorbing expansibility. This is a method of constructing a wall-shaped underground seismic isolation wall by excavating the ground in the planned drilling area with a drilling device and discharging the excavated soil to the ground, and protecting the hole wall of the underground hole The step of inserting a casing tube for the purpose of excavation and excavating and forming an underground hole in which the hole wall is protected by the casing tube, and then absorbing water from the ground via the hollow tube A slurry of a predetermined density made of an expandable clay-based material is injected and filled into the casing tube, and then the casing tube is removed to replace and fill one underground hole with a clay-based material having water-absorbing expandability. Repeat the process for each hole in the column. Therefore, it is possible to eliminate the possibility of collapse of the inner wall of the columnar underground hole, and the columnar underground hole is filled with a clay-based material having water absorption and expansion properties. The underground seismic isolation wall obtained in this way has the effect that it can be constructed relatively easily in situ using a casing tube and a hollow tube.

  Further, according to another method for constructing a ground-isolated wall according to the present invention, a porous tube is inserted into the central shaft portion of the underground hole that is replaced and filled with a clay-based material having water-absorbing expansibility. Since water with a lower electrolyte concentration than the pore water in the surrounding ground is poured, the clay-based material with water-absorbing expansibility filled in the underground pores is always saturated with water with a low electrolyte concentration and the water retention capability is maintained. The For this reason, the clay-based material can be maintained at a constant density for a long period of time without drying and shrinking, and the rigidity thereof can be kept small. As a result, it is possible to provide an underground seismic isolation wall that is excellent in long-term stability, because the displacement absorption capacity of the underground seismic isolation wall consisting of columnar underground holes, and thus the seismic isolation performance, is maintained. Play.

  In addition, according to another underground seismic isolation wall construction method according to the present invention, since the slurry to be injected and filled is a mixed material of ethanol water or salt water and bentonite, the viscosity of the slurry can be reduced, and the bentonite has a high concentration. It has the effect that it can be filled in the underground hole.

  Further, according to another method for constructing an underground seismic isolation wall according to the present invention, the slurry to be injected and filled is a mixed material of ethanol water or salt water, bentonite and aggregate, so that the viscosity of the slurry can be reduced, and bentonite Can be filled in the underground hole at a high concentration.

  Further, according to another underground seismic isolation wall construction method according to the present invention, the water-swellable clay-based material is a bentonite-based material, and the bentonite content per unit volume of the slurry to be filled is Since it is increased according to the depth of the borehole, it is possible to provide an underground seismic isolation wall that can sufficiently resist the lateral earth pressure received from the surrounding ground.

  In addition, according to the construction method of the other underground seismic isolation wall according to the present invention, the columnar underground holes excavated in the ground are continuously filled with a clay-based material having water-absorbing expansibility. This is a method of constructing a wall-shaped underground seismic isolation wall by excavating the ground in the planned drilling area with a drilling device and discharging the excavated soil to the ground, and protecting the hole wall of the underground hole The step of inserting a casing tube for the purpose of excavation to repeat the step of excavating and forming an underground hole in which the hole wall is protected by the casing tube, and then, in advance, partially or entirely absorbing water expandability By removing the casing tube after inserting the water-impervious bag loaded with the clay-based material into the casing tube, one underground hole is made into a water-impervious bag that is blocked from the surrounding groundwater Place the loaded clay-based material with water swellability. Since the underground seismic isolation wall is constructed by repeating the filling process for each hole in the columnar shape, the ground obtained by filling the columnar underground hole with a clay-based material having water absorption and expansion properties There is an effect that the middle seismic isolation wall can be constructed relatively easily in the original position using the casing tube and the water-impervious bag.

1-1 is a figure which shows the process 1 of Embodiment 1 of the construction method of the underground seismic isolation wall which concerns on this invention. 1-2 is a figure which shows the process 2 of Embodiment 1 of the construction method of the underground seismic isolation wall which concerns on this invention. 1-3 is a figure which shows the process 3 of Embodiment 1 of the construction method of the underground seismic isolation wall which concerns on this invention. FIGS. 1-4 is a figure which shows the process 4 of Embodiment 1 of the construction method of the underground seismic isolation wall which concerns on this invention. FIGS. 2-1 is a figure which shows the process 1 of Embodiment 2 of the construction method of the underground seismic isolation wall which concerns on this invention. FIGS. 2-2 is a figure which shows the process 2 of Embodiment 2 of the construction method of the underground seismic isolation wall which concerns on this invention. 2-3 is a figure which shows the process 3 of Embodiment 2 of the construction method of the underground seismic isolation wall which concerns on this invention. FIGS. 2-4 is a figure which shows the process 4 of Embodiment 2 of the construction method of the underground seismic isolation wall which concerns on this invention. 2-5 is a figure which shows the process 5 of Embodiment 2 of the construction method of the underground seismic isolation wall which concerns on this invention. FIG. 3-1 is a diagram showing a step 1 in the third embodiment of the underground seismic isolation wall construction method according to the present invention. 3-2 is a figure which shows the process 2 of Embodiment 3 of the construction method of the underground seismic isolation wall which concerns on this invention. FIG. 3-3 is a diagram showing a process 3 of the third embodiment of the underground seismic isolation wall construction method according to the present invention. FIG. 4-1 is a diagram showing a process 1 in the fourth embodiment of the underground seismic isolation wall construction method according to the present invention. FIG. 4-2 is a diagram showing a process 2 of the fourth embodiment of the underground seismic isolation wall construction method according to the present invention. FIG. 5 is a schematic cross-sectional perspective view showing a conventional ground displacement absorbing base isolation structure and an underground base isolation wall constituting the same. FIG. 6 is a cross-sectional perspective view showing an example of a columnar underground seismic isolation wall composed of a plurality of bags filled with water-absorbing expandable clay. FIG. 7 is a cross-sectional perspective view showing an example of a columnar underground seismic isolation wall in which a plurality of bags filled with water-absorbing expansive clay are staggered. FIG. 8 is a diagram showing the relationship between the ratio of the shear wave velocity of the underground wall material to the shear wave velocity of the surrounding ground and the seismic isolation effect. FIG. 9 is a graph showing the relationship between bentonite dry density and shear wave velocity.

  Below, an embodiment of a construction method of an underground seismic isolation wall concerning the present invention is described in detail based on a drawing. The underground seismic isolation wall construction method according to the present embodiment is a continuous wall-shaped ground by filling a columnar underground hole excavated in the ground with a clay-based material having water-absorbing expansibility. This is a method of constructing a middle seismic isolation wall. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
First, Embodiment 1 of the present invention will be described.
First, as shown in Step 1 of FIG. 1-1, the auger 10 is rotated and penetrated into the ground G, and the underground hole 12 is formed by excavation. Here, the auger 10 is constructed by attaching a spiral blade 16 to a long rotating rod 14 positioned on the auger rotation center axis, and a hollow tube 18 is inserted into the rotating rod 14. Yes. Further, during excavation of the underground hole 12, water, muddy water, air, or the like may be injected from the hollow tube 18 and injected from the tip of the auger 10 to facilitate excavation. On the other hand, as shown in step 2 of FIG. 1-2, the excavated soil 20 is discharged onto the ground GL by the rotation of the auger 10. The discharged excavated soil 20 is appropriately removed.

  Next, as shown in Step 3 of FIG. 1-3, the auger 10 is rotated and the excavated soil 20 is discharged to the ground, while the hollow tube 18 attached to the inside of the rotating rod 14 is passed through the hollow pipe 18. The bentonite slurry S (slurry) adjusted to the density is sent to the tip of the auger 10 and injected and filled into the space of the underground hole 12 from the tip of the auger 10. The auger 10 is pulled up according to the filling amount of the underground hole 12. 1-4, the bentonite slurry S is injected and filled into the space of the underground hole 12 from the tip of the auger 10 to replace the underground hole 12 with bentonite-based material (clay-based material). Fill.

  The above steps 1 to 4 are repeated for each of the central holes 12 in the form of a column of columns to construct an underground seismic isolation wall in the ground G. By doing so, the underground seismic isolation wall obtained by filling the columnar underground holes 12 with the bentonite-based material is relatively easily constructed in situ using the auger 10 and the hollow tube 18. Can do.

(Embodiment 2)
Next, a second embodiment of the present invention will be described.
First, as shown in step 1 of FIG. 2A, a casing pipe 28 for protecting the hole wall 12a of the underground hole 12 is installed at the mouth of the underground hole 12 before excavation, and the casing pipe 28 during excavation. Prepare for insertion. Then, the ground G in the planned excavation area of the underground hole 12 is excavated by the auger 22 (excavator). The auger 22 has a configuration in which a spiral blade 26 is attached to a long rotating rod 24 positioned on an auger rotation center axis. As the excavation progresses, the casing pipe 28 is inserted into the underground hole 12. As shown in Step 2 of FIG. 2B, the excavation of the underground hole 12, the discharge of the excavated soil 20 to the ground, and the insertion of the casing pipe 28 are repeated.

  As shown in Step 3 of FIG. 2C, after the excavation of the underground hole 12 is finished, the casing tube 28 is left and the auger 22 is removed. The underground hole 12 in which the hole wall 12 a is protected by the casing tube 28 is excavated and formed in the ground G. Thereafter, as shown in Step 4 of FIG. 2-4, the hollow pipe 30 is inserted into the casing pipe 28, and the bentonite slurry S (slurry) adjusted to a predetermined density from the ground is passed through the hollow pipe 30 to the casing pipe. The inside of 28 is injected and filled. When the inside of the casing tube 28 is replaced and filled with the bentonite material (clay material) by the bentonite slurry S, the casing tube 28 is pulled up and removed as shown in step 5 of FIG. 2-5.

  The above steps 1 to 5 are repeated for each of the central holes 12 in the form of a column, and an underground seismic isolation wall is constructed in the ground G. In this way, the underground seismic isolation wall obtained by filling the columnar underground holes 12 with the bentonite material is relatively easily constructed in situ using the casing tube 28 and the hollow tube 30. be able to.

(Embodiment 3)
Next, a third embodiment of the present invention will be described.
In the construction method of the underground seismic isolation wall according to the third embodiment, a porous tube is inserted into the central shaft portion of the underground hole 12 that is replaced and filled with the bentonite material in the first or second embodiment. Water that has an electrolyte concentration lower than the pore water in the surrounding ground is poured into the porous tube. Hereinafter, a case where the present invention is applied to the second embodiment will be described as an example.

  First, as shown in Step 1 of FIG. 3A, it is assumed that the underground hole 12 in which the hole wall 12 a is protected by the casing tube 28 is excavated and formed in the ground G by the auger 22. Next, as shown in step 2 of FIG. 3-2, the hollow tube 30 is inserted into the underground hole 12, and the bentonite slurry S (slurry) is passed through the hollow tube 30 from the ground to the inside of the casing tube 28. Fill with injection. After the inside of the casing tube 28 is replaced and filled with the bentonite material (clay material) by the bentonite slurry S, the casing tube 28 is pulled up and removed.

  Next, as shown in Step 3 of FIG. 3C, the porous tube 32 is inserted to the lower end of the central shaft portion of the underground hole 12 that is replaced and filled with the bentonite slurry S. Then, water W having an electrolyte concentration lower than the pore water in the surrounding ground G is poured into the porous tube 32. In the present embodiment, the underground hole 12 is not completely replaced by the bentonite slurry S, and a space is secured inside the underground hole 12 above the bentonite slurry S. In this space, a water tank made of the water W is formed, and a casing pipe 34 constituting the wall of the water tank is provided in the hole wall 12a of this portion. The upper part of the water tank is closed with a lid 36. With this water tank, water W having a low electrolyte concentration can be constantly supplied to the porous tube 32.

  As a result, the bentonite material filled in the underground hole 12 is always saturated with the water W having a low electrolyte concentration, and the water retention capacity is maintained. For this reason, the bentonite-based material can maintain its constituent material density constant for a long period of time without drying and shrinking, and can maintain its rigidity in a small state. As a result, it is possible to provide the underground seismic isolation wall having excellent long-term stability while maintaining the displacement absorption capability of the underground seismic isolation wall composed of the columnar underground holes 12 and the seismic isolation performance.

(Embodiment 4)
Next, a fourth embodiment of the present invention will be described.
First, as shown in Step 1 of FIG. 4-1, a casing pipe 38 for excavating the underground hole 12 with an unillustrated excavator and protecting the hole wall 12a of the underground hole 12 as the excavation progresses is provided. Insert and arrange. Subsequently, a water-impervious bag 40 in which bentonite-based material M (clay-based material) is partially or entirely loaded in advance is inserted into the casing tube 38.

  Next, as shown in step 2 of FIG. 4B, the bentonite-based material loaded in a water-impervious bag 40 in which the casing pipe 38 is pulled up and removed, and one underground hole 12 is blocked from the surrounding ground water. Replace with M.

  The above-described steps 1 and 2 are repeatedly performed for each of the central holes 12 in the form of a column, and an underground seismic isolation wall is constructed in the ground G. In this way, the underground seismic isolation wall obtained by filling the columnar underground holes 12 with the bentonite-based material is relatively easily constructed in situ using the casing tube 38 and the water-impervious bag 40. can do.

  In the above-described embodiment, above the bentonite material M in the bag 40, a soil material such as water having a lower electrolyte concentration than the surrounding ground water or sand containing similar water in the gap may be disposed. In this way, the same effects as those of the third embodiment can be obtained. Moreover, you may comprise the bentonite-type material M inside the bag 40 with the mixed material of ethanol water or salt water, bentonite, and an aggregate. Even if it does in this way, there can exist an effect similar to said Embodiment 3. FIG.

(Embodiment 5)
Next, a fifth embodiment of the present invention will be described.
The construction method of the underground seismic isolation wall according to the fifth embodiment is the same as in the first to third embodiments described above, with the bentonite slurry S to be injected and filled into the underground hole 12 being a mixture of ethanol water or salt water and bentonite. It is a thing.

  It is known that a slurry in which bentonite and ethanol water are kneaded or a slurry in which bentonite and an aqueous electrolyte solution (for example, salt water) are kneaded can have a smaller viscosity than a slurry in which bentonite and water are kneaded.

For example, according to the following publication A, the bentonite slurry shown in Table 1 is connected to a commercially available MONO pump (pump maximum pressure 1.2 MPa) and a pressure-resistant rubber hose (outer diameter 61 mm, inner diameter 50.8 mm) with an extension of 20 m. As a result of the pumping experiment, it was difficult to pump a slurry having a bentonite concentration of 0.2 Mg / m ³ (0.2 g / cm ³ ) when bentonite and water were kneaded, whereas bentonite and a 4 wt% NaCl solution In the case of a slurry in which bentonite was kneaded or a slurry in which bentonite and 60 wt% ethanol water were kneaded, it could be pumped to a bentonite concentration of 0.8 Mg / m ³ (0.8 g / cm ³ ). Therefore, it turns out that it is easy to fill with the underground hole. For this reason, according to this Embodiment, the viscosity of a slurry can be made small and a ground hole can be filled with bentonite with high concentration.

[Public Publication A] Nuclear Environment Improvement Promotion and Funds Management Center, “Fiscal 2007 Survey on Geological Disposal Technologies, etc. High-Level Radioactive Waste Disposal Related Disposal System Engineering Element Technology Advancement Development Report”, March 2008, pp. 3-255-3-283

  The bentonite slurry S to be injected and filled may be a mixed material of ethanol water or salt water, bentonite and aggregate. Even if it does in this way, the viscosity of a slurry can be made small and a underground hole can be filled with a high concentration of bentonite.

(Embodiment 6)
Next, a sixth embodiment of the present invention will be described.
In the construction method of the underground seismic isolation wall according to the sixth embodiment, the bentonite content per unit volume of the bentonite slurry S to be injected and filled into the underground hole 12 in the above first to third embodiments It is enlarged according to the depth of the hole 12. By setting the bentonite content to a deeper position, the underground seismic isolation wall that can sufficiently resist the lateral earth pressure received from the surrounding ground can be provided. Note that the detailed operation principle of the present embodiment is described in the detailed description of the invention related to Japanese Patent Application No. 2013-146579 filed by the present applicant.

  As described above, according to the construction method of the underground seismic isolation wall according to the present invention, by filling the columnar underground hole excavated in the ground with a clay-based material having water-absorbing expansibility, A method of constructing a continuous wall-shaped underground seismic isolation wall by excavating and forming an underground hole with an auger and discharging the excavated soil to the ground, and through a hollow tube attached to the central axis of the auger Then, a slurry of a predetermined density made of clay-based material having water-absorbing expansibility from the ground is fed to the tip of the auger and injected into the space of the underground hole from the auger tip, so that one underground hole has the water-absorbing expansibility. The process of replacing and filling with clay-based materials is repeated for each of the boreholes in the columnar shape to build the underground seismic isolation wall, eliminating the possibility of collapse of the inner wall of the columnar underground hole. , Clay-based material with water-absorbing expansibility in columnar underground holes Underground MenShinkabe obtained by Hama, can be constructed relatively easily in situ using auger and hollow tubes.

  In addition, according to the construction method of the other underground seismic isolation wall according to the present invention, the columnar underground holes excavated in the ground are continuously filled with a clay-based material having water-absorbing expansibility. This is a method of constructing a wall-shaped underground seismic isolation wall by excavating the ground in the planned drilling area with a drilling device and discharging the excavated soil to the ground, and protecting the hole wall of the underground hole The step of inserting a casing tube for the purpose of excavation and excavating and forming an underground hole in which the hole wall is protected by the casing tube, and then absorbing water from the ground via the hollow tube A slurry of a predetermined density made of an expandable clay-based material is injected and filled into the casing tube, and then the casing tube is removed to replace and fill one underground hole with a clay-based material having water-absorbing expandability. Repeat the process for each hole in the column. Therefore, it is possible to eliminate the possibility of collapse of the inner wall of the columnar underground hole, and the columnar underground hole is filled with a clay-based material having water absorption and expansion properties. The underground seismic isolation wall obtained in this way can be constructed relatively easily in situ using a casing tube and a hollow tube.

  Further, according to another method for constructing a ground-isolated wall according to the present invention, a porous tube is inserted into the central shaft portion of the underground hole that is replaced and filled with a clay-based material having water-absorbing expansibility. Since water with a lower electrolyte concentration than the pore water in the surrounding ground is poured, the clay-based material with water-absorbing expansibility filled in the underground pores is always saturated with water with a low electrolyte concentration and the water retention capability is maintained. The For this reason, the clay-based material can be maintained at a constant density for a long period of time without drying and shrinking, and the rigidity thereof can be kept small. As a result, it is possible to provide an underground seismic isolation wall having excellent long-term stability while maintaining the displacement absorption capacity of the underground seismic isolation wall made up of columnar underground holes, and hence the seismic isolation performance.

  In addition, according to another underground seismic isolation wall construction method according to the present invention, since the slurry to be injected and filled is a mixed material of ethanol water or salt water and bentonite, the viscosity of the slurry can be reduced, and the bentonite has a high concentration. It is possible to fill the underground hole.

  Further, according to another method for constructing an underground seismic isolation wall according to the present invention, the slurry to be injected and filled is a mixed material of ethanol water or salt water, bentonite and aggregate, so that the viscosity of the slurry can be reduced, and bentonite Can be filled into the underground hole at a high concentration.

  Further, according to another underground seismic isolation wall construction method according to the present invention, the water-swellable clay-based material is a bentonite-based material, and the bentonite content per unit volume of the slurry to be filled is Since it is increased according to the depth of the borehole, it is possible to provide an underground seismic isolation wall that can sufficiently resist the lateral earth pressure received from the surrounding ground.

  In addition, according to the construction method of the other underground seismic isolation wall according to the present invention, the columnar underground holes excavated in the ground are continuously filled with a clay-based material having water-absorbing expansibility. This is a method of constructing a wall-shaped underground seismic isolation wall by excavating the ground in the planned drilling area with a drilling device and discharging the excavated soil to the ground, and protecting the hole wall of the underground hole The step of inserting a casing tube for the purpose of excavation to repeat the step of excavating and forming an underground hole in which the hole wall is protected by the casing tube, and then, in advance, partially or entirely absorbing water expandability By removing the casing tube after inserting the water-impervious bag loaded with the clay-based material into the casing tube, one underground hole is made into a water-impervious bag that is blocked from the surrounding groundwater Place the loaded clay-based material with water swellability. Since the underground seismic isolation wall is constructed by repeating the filling process for each hole in the columnar shape, the ground obtained by filling the columnar underground hole with a clay-based material having water absorption and expansion properties The middle seismic isolation wall can be constructed relatively easily in situ using a casing tube and a water-tight bag.

  As described above, the construction method of the underground seismic isolation wall according to the present invention is an underground seismic isolation that constitutes a ground displacement absorbing base isolation structure for reducing stress on underground structures such as open tunnels during an earthquake. It is useful for a seismic wall, and is particularly suitable for constructing an in-situ seismic isolation wall obtained by filling a columnar underground hole with a clay-based material having water absorption and expansion properties.

1 Surrounding ground 2 Underground structure 3 Underground seismic isolation wall (underground wall)
DESCRIPTION OF SYMBOLS 10 Auger 12 Underground hole 12a Hole wall 14, 24 Rotating rod 16, 26 Spiral blade 18, 30 Hollow tube 20 Excavated soil 22 Auger (excavator)
28, 34, 38 Casing tube 32 Porous tube 36 Lid 40 Bag G Ground GL Ground M Bentonite material (clay material)
S Bentonite slurry (slurry)
W Water

Claims (8)

A method for constructing a continuous wall-shaped underground seismic isolation wall by filling a columnar underground hole formed by excavation in the ground with a clay-based material having water-absorbing and expanding properties,
Excavating and forming underground holes with auger and discharging excavated soil to the ground;
By sending a slurry of a predetermined density made of clay-based material having water-absorbing and expanding properties from the ground via a hollow tube attached to the auger central shaft to the auger tip, and filling and filling the space of the underground hole from the auger tip, Replacing and filling one underground hole with a clay-based material having a water-swelling property;
A method for constructing an underground seismic isolation wall, characterized by repeatedly constructing an underground seismic isolation wall for each central hole in a columnar shape. A method for constructing a continuous wall-shaped underground seismic isolation wall by filling a columnar underground hole formed by excavation in the ground with a clay-based material having water-absorbing and expanding properties,
Excavating the ground in the planned excavation area with the excavator and discharging the excavated soil to the ground; and inserting a casing pipe for protecting the hole wall of the underground hole as the excavation progresses; Repeatedly excavating and forming an underground hole in which the hole wall is protected by the casing tube;
After that, a slurry of a predetermined density made of clay-based material having water-absorbing expansibility is injected into the casing pipe through the hollow pipe, and then the casing pipe is removed, thereby removing one underground hole. Replacing and filling with a clay-based material having water absorbability,
A method for constructing an underground seismic isolation wall, characterized by repeatedly constructing an underground seismic isolation wall for each central hole in a columnar shape.   Insert a perforated tube into the center shaft of the underground hole that is replaced and filled with a clay-based material with water-absorbing expansibility, and inject water into the perforated tube with an electrolyte concentration lower than the pore water in the surrounding ground. The construction method of the underground seismic isolation wall according to claim 1 or 2, characterized in.   The construction method of the underground seismic isolation wall according to any one of claims 1 to 3, wherein the slurry to be injected and filled is a mixed material of ethanol water or salt water and bentonite.   The construction method of the underground seismic isolation wall according to any one of claims 1 to 3, wherein the slurry to be injected and filled is a mixed material of ethanol water or salt water, bentonite and aggregate.   The clay-based material having water absorbability is a bentonite-based material, and the bentonite content per unit volume of the slurry to be injected and filled is increased according to the depth of the underground hole. The construction method of the underground seismic isolation wall as described in any one. A method for constructing a continuous wall-shaped underground seismic isolation wall by filling a columnar underground hole formed by excavation in the ground with a clay-based material having water-absorbing and expanding properties,
Excavating the ground in the planned excavation area with the excavator and discharging the excavated soil to the ground; and inserting a casing pipe for protecting the hole wall of the underground hole as the excavation progresses; Repeatedly excavating and forming an underground hole in which the hole wall is protected by the casing tube;
After that, by inserting a water-impervious bag preliminarily or partially filled with a clay-based material having water-absorbing expansibility into the casing tube, the casing tube is removed to surround one underground hole. Replacing and filling with a clay-based material having a water-swelling property loaded in a water-impervious bag that is blocked from the groundwater of
A method for constructing an underground seismic isolation wall, characterized by repeatedly constructing an underground seismic isolation wall for each central hole in a columnar shape.   The construction method of an underground seismic isolation wall according to claim 7, wherein the clay-based material loaded in the water-impervious bag is a mixed material of ethanol water or salt water, bentonite and aggregate.

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