JP4961538B2 - Ground stabilization method - Google Patents

Description

  The present invention relates to a ground stabilization method, and by draining groundwater with a pipe body having a drainage function and reinforcing the ground, and further compacting the ground with a bag filled with a consolidation material, Such inherently unstable ground can be effectively reinforced.

  It is known that ground that is inherently unstable, such as land created by valley filling embankments with a gentle slope, can cause large ground disasters such as landslides during heavy rains or earthquakes. Yes.

  And ground disasters such as landslides are often caused mainly by the phenomenon of groundwater infiltrating into the ground. The ground strength (shear resistance) decreases due to groundwater infiltration, the groundwater pressure increases due to the increase in groundwater level, It is said that this occurs due to liquefaction caused by an increase in pore water pressure during an earthquake.

  For this reason, when such land is created, sufficient stabilization of the ground is required along with the creation work. Such ground stabilization methods include: (1) Inserting a reinforcing bar with mortar and other solidified material into a hole formed by boring, etc., and fixing the reinforcing bar in the ground with the solidified material. Reinforcing method, (2) Inserting an injection tube into the drilling hole, injecting a caking material into the ground through the injection tube and solidifying the entire ground, and (3) In the drilling hole By inserting an injection tube fitted with a bag body and injecting a solidified material such as plastic gel or cement grout into the bag body through the injection tube, a mass consolidated body is formed in the ground. A method of reinforcing the ground by using the consolidation effect of the ground is known.

JP-A-62-82113 Japanese Patent Laid-Open No. 04-281912 JP 2008-291437 A Patent No. 2509005

  However, in the method (1), since there is no particular consideration for draining groundwater, there is a problem that fundamental reinforcement cannot be made against ground disasters such as landslides. In the method (2), although the ground strength is increased, the water permeability of the ground is decreased, so that the water pressure on the back surface is increased, which may cause the collapse of the natural ground. And the method of (3) is a method of filling the bag body with a solidified material such as a plastic gel through the tube body to form a massive solid body, particularly when the bag body is impermeable. During filling, the bag body expands in proportion to the amount of solidified material, but after the completion of filling of the solidified material, the solidified material gradually solidifies, but the excess water contained in the solidified material is reduced. In some cases, the bag body is separated and pulled out of the bag body. As a result, the bag body contracts and the consolidation effect as expected is not obtained.

  In addition, when the bag body is water permeable, a part of the consolidated material is pulled out of the bag body, so that the required size of the consolidated body cannot be formed, and the consolidation effect as expected cannot be obtained. was there. Furthermore, there was also a risk of clogging the water transmission port of the pipe body by escaping in the axial direction of the pipe body.

  The present invention was made to solve the above problems, and drains groundwater, which is a major cause of causing ground disasters, with a tubular body having a drainage function, and at the same time strengthens the ground by the tensile resistance of the tubular body. Further, it is an object of the present invention to provide a ground stabilization method that enables effective reinforcement of unstable ground by compacting the ground with a bag body filled with a binder.

The ground stabilization method according to claim 1 is a method of inserting a pipe body having a water permeability opening provided with a water-permeable bag body and a filter for preventing inflow of earth and sand into the drilling hole, and placing the pipe body outside the pipe body. The tube body is injected into the bag body through a pipe and the bag body is inflated to fix the pipe body in a drilling hole, and drains groundwater to the ground surface through the pipe body from the water permeable port. It is characterized by strengthening the ground by the tensile resistance of the body.

  The present invention eliminates the main cause of causing ground disaster by draining groundwater in the ground through the pipe, and at the same time gives the pipe a tensile resistance against the spread of the ground in the event of landslide etc. The effective ground is strengthened and the ground is stabilized.

  Drainage function and tension for perforated steel pipes (such as steel sheet piles that have a drainage function by having a water permeable opening and slits), glass fiber reinforced resin perforated pipes, and RC structure perforated pipes A tube having strength can be used. Further, the water-permeable port includes a slit, and the slit elongated in the longitudinal direction of the tube body can efficiently permeate the groundwater into the tube body.

  For water-permeable bags, bags made of high-strength fibers such as aramid fibers and geotextiles are suitable in addition to hemp bags, and plastic gels, quick-setting grouts, cement grouts, etc. may be used for the consolidated material. it can.

  An injection tube (double packer) or the like can be used to inject the consolidated material into the bag. Alternatively, an injection tube that leads to each bag body is attached to the outside of the tube body, for example, and can be directly injected into each bag body through this injection tube.

The ground stabilization method according to claim 2 is an injection in which a pipe body having a water permeability opening provided with a water-permeable bag body and a filter for preventing inflow of earth and sand is inserted into the drilling hole and installed outside the pipe body. excess pore by the tube body fixed to the boring by inflating the bag body by injecting consolidating material into the bag through the tube, draining the ground water to the surface through the tubular body from said water permeable port While suppressing the rise in water pressure to prevent liquefaction, the ground is strengthened by the tensile resistance of the tubular body.

  The present invention is a ground stabilization method especially for liquefaction during an earthquake, and the increase of excess pore water pressure is suppressed by draining groundwater around the pipe through the pipe through the pipe through the pipe during the earthquake. This makes it possible to stabilize the ground.

  For this reason, even if the ground including the pipe periphery is liquefied due to large earthquake motion, after the earthquake ends, the excess pore water pressure in the surrounding ground is quickly dissipated to quickly restore the current situation, thereby improving the structure and ground on the ground. Can be reduced.

  The pipe body in this case includes a steel pipe pile provided with drain holes or slits for drainage, a hollow part for drains continuous in the axial direction of the material, and a steel sheet pile provided with holes or slits communicating with the hollow parts. It is suitable because it can also serve as a structural member that supports a structure on the ground and a retaining wall that prevents lateral flow of earth and sand.

  In addition, the fall of the drainage function of a pipe body can be prevented by attaching the filter for earth and sand inflow prevention to the through-hole and slit of a pipe body. Further, by forming a mat drain by spreading sand or crushed stone on the ground surface to a predetermined thickness, the groundwater drained to the ground through the pipe can be treated promptly.

The ground stabilization method according to claim 3 is an injection in which a pipe body having a water permeability opening provided with a water permeable bag body and a filter for preventing inflow of earth and sand is inserted into the drilling hole and installed outside the pipe body. together with the tube body fixed to the boring by inflating the bag body by injecting consolidating material into the bag, to drain groundwater to the surface through the tubular body from the water permeable hole through the tube, the tube It is characterized in that the ground is strengthened by the tensile resistance of the tensile reinforcement placed on the body.

  The present invention is a method suitable particularly when a perforated pipe having a low tensile strength, such as a perforated pipe made of plastic or PVC, is used as a tubular body. Even when a perforated tube having a tensile strength is used as a tubular body, it can be implemented.

  In this case, a reinforcing steel (such as a reinforcing steel cage), a steel material (lightweight profile, etc.), and a PC steel (PC steel wire, etc.) can be used as the tensile reinforcing material. Further, the tensile reinforcing material can be installed on one or both of the outer side and the inner side of the tubular body.

  When installing the tensile reinforcement on the outside of the pipe, for example, install a tensile reinforcement made of a reinforcing steel cage, attach a metal mesh or resin net to the outer periphery, and fill it with a water-absorbing filler such as a sponge. By filling, it is possible to prevent the water-permeable opening from being clogged with slime or the like in the hole. Moreover, a steel pipe can be installed as a tensile reinforcement and can also be used as an injection pipe for injecting the consolidated material into the bag body.

  On the other hand, when installing the tensile reinforcement inside the pipe, a reinforcing bar or PC steel bar is suitable as the tensile reinforcement, and these tensile reinforcements are fixed in the bore after fixing the pipe in the drilling hole. Inserted from the ground surface, its tip penetrates the tip of the tube, or penetrates the tube, and settles in the ground before it. Can be granted.

  The ground stabilization method according to claim 4 is the ground stabilization method according to any one of claims 1 to 3, wherein the bag body is inflated to push the hole wall of the drilling hole, thereby compacting the ground. It is characterized by strengthening.

  The present invention makes it possible to reinforce the ground by utilizing the compaction effect due to the compaction of the ground due to the expansion of the bag body. According to the present invention, the reinforcement by drainage of groundwater and the tubular body or the tensile reinforcement In addition to the reinforcement by the tensile resistance force, the unstable ground can be more strongly reinforced by the three reinforcement methods of the reinforcement by the compaction of the ground by the bag body filled with the binder.

  The present invention drains groundwater through a tubular body having a drainage function and simultaneously reinforces the ground by the tensile resistance of the tubular body, and further reinforces the ground by compaction with a bag filled with a consolidated material, thereby filling the valley. Unstable ground like embankment can be reinforced very effectively.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of the present invention, (a) is a cross-sectional view showing the ground of a valley-filled embankment, (b) is a cross-sectional view of a dike, and (c) is a cross-sectional view showing the ground of a landfill. The tubular body inserted in the drilling hole is shown, (a) is a partial side view thereof, and (b), (c), (d) are transverse sectional views thereof. It is a partial side view of a tubular body showing a case where a tensile reinforcing material is installed in the tubular body. A method for injecting a caking material into a water-permeable bag is shown, (a) and (b) are partial side views of the tube, and (c) is a transverse cross-sectional view thereof.

  1 to 4 show a ground of a valley-filled embankment reinforced by the present invention. In the figure, a tubular body 2 is inserted into a borehole 1 formed by boring with a constant water gradient. . A perforated steel pipe is used for the pipe body 2, a plurality of water-permeable ports 2 a are formed on the peripheral wall of the pipe body 2 at regular intervals, and a plurality of water-permeable holes are formed on the outer periphery of the pipe body 2. The bag body 3 is attached at regular intervals in the longitudinal direction of the tube body 2.

  In addition to the perforated steel pipe, the tubular body 2 may be a perforated pipe made of plastic, a perforated pipe made of glass fiber reinforced resin, a perforated pipe made of PVC, or a perforated pipe having an RC structure. In particular, for a perforated pipe having a poor tensile strength, such as a plastic or PVC perforated pipe, a plurality of tensile reinforcement members composed of reinforcing bars or the like on the outer periphery of the pipe body 2 as shown in FIG. Tensile strength is given by tying 4 and attaching.

  In this case, the tensile reinforcement member 4 is attached in a lattice shape in the longitudinal direction and the circumferential direction of the tube body 2, and in particular, the circumferential tensile reinforcement member 4 is attached spirally in the longitudinal direction of the tube body 2. Is preferable in terms of strength.

  Furthermore, as shown in FIG. 2 (d), by filling the inner side of the tensile reinforcement member 4 attached in a lattice shape with a filler 5 having a high water absorption property such as a sponge, the water-permeable port 2 a is formed in the hole 1. Consideration is made so that the water permeability does not deteriorate due to clogging with slime.

  FIG. 3 shows a case in which a tensile reinforcement member is installed in the pipe body. After fixing the pipe body 2 in the drilling hole 1, the tensile reinforcement member 4 is inserted into the pipe body 2 from the ground surface side and installed. The distal end 4a penetrates through the distal end portion of the tube body 2 or the tube body 2 and is fixed by the solidifying material 6 in the ground beyond the distal end. Then, the end 4b on the ground surface may be fixed on the ground surface. Thereby, the tensile resistance can be applied to the tube body 2.

  In this case, the tensile reinforcement member 4 can be a reinforcing bar, a PC steel rod, or the like, and the tensile reinforcement member 4 can be tensioned to introduce prestress into the tube body 2. Furthermore, when fixing the tip 4a of the tensile reinforcing material 4 to the tip of the tubular body 2, the consolidated material 6 directly fills the distal end of the tubular body 2, and the distal end 4a of the tensile reinforcing material 4 penetrates the tubular body 2. When fixing in the ground at the tip, as shown in the figure, the bag 3 previously attached to the tip of the tube 2 may be filled.

  The water-permeable bag 3 is a bag made of high-strength fibers such as non-woven fabric, geotextile, and aramid fiber in addition to the hemp bag, and is attached so as to surround the tube body 2.

  And each permeable bag body 3 is expanded so as to strongly push the hole wall around the tube body 2 by being filled with the consolidation material 6, thereby forming the respective massive solid bodies 7. The tube body 2 is fixed integrally with the surrounding ground in the drilling hole 1. Further, the base end side of the tube body 2 protrudes from the embankment slope reinforced by the retaining wall 8 and serves as a drain port 2b.

  The consolidated material 6 is made of plastic gel, quick setting grout, cement grout or the like. In particular, the plastic gel is filled in the water-permeable bag body 3 so that the bag does not leak to the surroundings. The body 3 can be expanded to reliably form a massive solid body 7 having a required diameter.

  Moreover, since the circumference | surroundings of the pipe body 2 are not missed in the longitudinal direction, the fixed area of the pipe body 2 which has the water-permeable opening 2a is hold | maintained, and there is no possibility of clogging the water-permeable opening 2a.

  In order to fill the bag 3 with the consolidated material 6, an injection tube (such as a double packer) 9 as shown in FIG. 4A is used. The injection pipe 9 is inserted into the pipe body 2 from the drain port 2 b, and the consolidated material 6 is filled into the bag body 3 through the injection pipe 9. And as soon as the filling operation of the consolidated material 6 is completed, the injection tube 9 is removed.

  As another method for filling the bag material 3 with the consolidated material 6, as shown in FIG. 4 (b), injection pipes 10a, 10b, 10c leading to each bag body 3 are provided on the outer periphery of the tube body 2. Alternatively, a method may be used in which each bag body 3 is directly filled with the consolidated material 6 through the injection pipes 10a, 10b, and 10c. The injection pipes 10a, 10b, 10c are left in the drilling hole 1.

  Further, as shown in FIG. 4 (c), these injection pipes 10a, 10b, 10c may be formed from a steel pipe and used also as a tensile reinforcement. According to this method, the consolidated material 6 can be easily and reliably filled in each bag 3.

  Further, since one of the injection tube and the tensile reinforcing material can be omitted, it is possible to reduce the number of members used and to save labor and cost. In addition, a steel pipe can be utilized for the injection pipes 10a, 10b, and 10c, and can also be helically attached to the outer periphery of the pipe body 2.

  In such a configuration, groundwater in the ground permeates into the pipe body 2 from the water permeability port 2a and drains from the drainage port 2b on the surface through the pipe body 2, thereby eliminating the retention of groundwater and lowering the pore water pressure. By being able to make it possible, it is possible to prevent the ground from collapsing due to a decrease in ground strength, a landslide and a landslide due to an increase in the water pressure of the back soil, and an unstable ground can be strengthened to a stable ground.

  In particular, for the spread of the ground in the case of landslides, the tensile resistance force of the tube body 2 or the tensile reinforcing material 4 is applied to the ground through a plurality of massive solid bodies 7 corresponding to the partition walls. Therefore, it is possible to prevent a large landslide disaster.

  Furthermore, the unstable ground can be strengthened to a stronger ground by gradually expanding the bag body 3 so as to push the hole wall of the drilling hole 1 and compacting the surrounding ground.

  FIG. 1 (b) shows an embodiment of the present invention in a dike constructed along a river, and FIG. 1 (c) shows an embodiment of the present invention in a landfill such as a coastal industrial zone. However, in such landfills near the river and the sea, there is a risk that pore water pressure will rise due to vibrations during earthquakes and cause liquefaction.

  As a result of the application of the present invention, groundwater penetrates into the pipe body 2 from the water inlet 2a of the pipe body 2 provided under the groundwater surface, rises through the pipe body 2, and drains from the ground outlet port 2b. Since the increase in the pore water pressure is suppressed, liquefaction of the ground is suppressed, so that the stable state of the embankment 12 and the ground structure 13 can be maintained.

  In this case, in particular, the pipe body 2 is a steel pipe pile provided with drain holes or slits for drainage, or a steel sheet pile provided with drain holes and slits communicating with the hollow parts continuous in the axial direction of the material. Etc. are used. Moreover, what is necessary is just to fix the edge part by the side of the ground surface of each pipe body 2 to the bearing plate 14 which consists of RC plates etc. which were installed in the ground surface.

  Furthermore, in landfills such as the coastal industrial zone shown in FIG. 1 (c), sand and crushed stone are spread on the ground surface to a certain thickness to form a mat drain 15 through each pipe 2 above the ground. The groundwater drained into the water can be treated promptly.

  Note that the pipe body 2 may be installed vertically around the embankment 12 and the structure 13 or obliquely from the periphery of these structures toward the direction directly below the structure. It is also possible to introduce prestress by tensioning the tube body 2.

  The present invention can effectively reinforce unstable ground by draining groundwater as a main cause of causing ground disasters such as landslides and simultaneously strengthening the ground.

DESCRIPTION OF SYMBOLS 1 Drilling hole 2 Tubing body 2a Permeation port 2b Drainage port 3 Permeable bag body 4 Tensile reinforcement 5 Filler rich in water absorption 6 Consolidation material 7 Consolidation body 8 Retaining wall 9 Injection tube 10a Injection tube 10b Injection tube 10c Injection pipe 11 Filter 12 Embankment 13 Structure 14 Bearing plate 15 Mat drain

Claims (4)

Insert a tube body with a water permeable bag body and a water permeable opening with a filter for preventing sediment inflow into the drilling hole, and inject the consolidated material into the bag body through an injection pipe installed outside the tube body. Then, the tubular body is fixed in the drilling hole by inflating the bag body, groundwater is drained to the ground surface through the tubular body from the water-permeable port, and the ground is strengthened by the tensile resistance force of the tubular body. A ground stabilization method characterized by Insert a tube body with a water permeable bag body and a water permeable opening with a filter for preventing sediment inflow into the drilling hole, and inject the consolidated material into the bag body through an injection pipe installed outside the tube body. and the tube body fixed to the boring by inflating the bag body, prevent and suppress the increase of the excess pore water pressure liquefaction by draining the ground water to the surface through the tubular body from said water permeable port And a ground stabilization method characterized by strengthening the ground by the tensile resistance of the tubular body. Insert a tube body with a water permeable bag body and a water permeable opening with a filter for preventing sediment inflow into the drilling hole, and inject the consolidated material into the bag body through an injection pipe installed outside the tube body. and the tube body fixed to the boring by inflating the bag body, wherein while draining the ground water to the surface through the tubular member from the permeable opening, the tensile resistance force of the tension reinforcement disposed in said tubular body A ground stabilization method characterized by strengthening the ground.   The ground stabilization method according to any one of claims 1 to 3, wherein the ground is compacted and strengthened by expanding the bag body so as to push the hole wall of the drilling hole.

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