JP4874224B2 - Drain material and ground improvement device - Google Patents

Description

  The present invention relates to a drain material used to improve the soft ground by discharging moisture and the like contained in the ground softening the ground, and a ground improvement device using the drain material.

  As a method for improving the soft ground by discharging moisture in the soft ground, the ground surface is covered with a sand mat made of sand that has water permeability, and vertical drain material is applied in the vertical direction of the ground. The construction method is known.

  In addition, vertical drain material is placed in soft ground, this soft ground is covered with a sealing sheet, moisture in the ground is extracted through the vertical drain material, and soft ground improvement method by vacuum consolidation that promotes consolidation of the ground The so-called atmospheric pressure method is also known. This atmospheric pressure construction method creates a vacuum state in the soft ground by covering the soft ground with a sealing sheet to consolidate the soft ground, and connect a pump as a decompression means to the vertical drain material facing the ground surface. By doing so, the water | moisture content etc. in a soft ground can be discharged | emitted.

  Further, in another soft ground improvement method, instead of using a sealing sheet, there is an air-impermeable portion that has water permeability inside the end portion by a certain length from the end portion and blocks ventilation from the peripheral surface. There is also known a method of using a ground material from a ground surface to a predetermined depth as a sealing layer using a provided drain material. Furthermore, it is also known to artificially form a sealing layer by applying clay-like embankment on the ground surface.

  These construction methods are appropriately selected by a contractor or the like in consideration of various circumstances such as preparation and removal of embankment, sealing sheets, and the cost required for these. However, no matter which method is selected, the drain material is indispensable.

  By the way, the drain material that has been used to improve soft ground by the above-mentioned method has a constant cross-sectional dimension for both the vertical drain material and the horizontal drain material, and attention is paid to the change in the flow rate of water flowing through the drain material. There were few things I did.

JP 2001-226951 A

  Therefore, the present invention has been made in view of the above circumstances, and a drain material capable of reducing the cost by suppressing the cost while improving the water flow capacity or maintaining the water flow capacity, and this An object of the present invention is to provide a ground improvement device using a drain material.

  In order to solve the above-described problem, a drain material according to the present invention is surrounded by a long outer wall part partially or entirely permeable to water and the outer wall part, and communicated in the longitudinal direction of the outer wall part. A hollow portion serving as a flow path, and the outer wall portion is characterized in that a cross-sectional area of the hollow portion decreases from one end portion to the other end portion in the longitudinal direction.

  Further, the outer wall portion may be configured such that the cross-sectional area of the hollow portion decreases from one end portion to the other end portion in the longitudinal direction for a while or in stages.

  Further, the ground improvement device according to the present invention is a ground improvement device that drains moisture in the ground to improve the ground, and is a long outer wall portion that is placed on the ground and partly or entirely has water permeability. A vertical drain member having a hollow portion surrounded by the outer wall portion and communicating with a longitudinal direction of the outer wall portion, and communicated with the hollow portion of the vertical drain material at one end portion of the vertical drain material. A horizontal drain material having a long outer wall portion and a hollow portion that is surrounded by the outer wall portion and communicates in the longitudinal direction of the outer wall portion, the vertical drain material and / or the horizontal drain material. The drain material is characterized in that each outer wall portion has a smaller cross-sectional area of the hollow portion from one end portion to the other end portion in the longitudinal direction.

  The present invention is a drain material having a structure in which the outer wall portion has a structure in which the cross-sectional area of the hollow portion decreases from one end portion to the other end portion in the longitudinal direction, and has a cross-sectional area of the hollow portion corresponding to the flow rate. Therefore, the cost can be reduced as compared with the conventional case.

  Hereinafter, embodiments of a ground improvement device according to the present invention and a drain material used in the ground improvement device will be described in detail with reference to the drawings.

  As shown in FIG. 1 to FIG. 3, the ground improvement device 1 was placed on the ground surface 2 a and the vertical drain material 10 placed in the soft ground 2 facing the ground surface 2 a with a predetermined length. A first ground layer 3, a horizontal drain material 20 disposed on the first bank layer 3 and connected to the vertical drain material 10, and the soft ground 2 covering the horizontal drain material 20 and including the horizontal drain material 20. It is comprised from the 2nd embankment layer 4 piled up so that it might seal.

  The ground improvement device 1 includes a vertical drain material 10 in which the soft ground 2 is consolidated by an embankment layer 3 piled on the soft ground 2, and is placed on the soft ground 2 to a predetermined depth, and the vertical drain material 10. By the horizontal drain material 20 connected to, water, air, etc. in the ground are discharged in the directions indicated by arrows A and B in FIG. 1 and the ground is improved. As shown in FIGS. 2 and 3, the ground improvement device 1 is, for example, 30 to 50 [m] at an interval of about 1 [m] on the soft ground 2 in 300 [m] square as shown in FIGS. 2 and 3. A horizontal drain material 20 is connected to the vertical drain material 10 placed in a grid pattern at a depth of 3 mm to discharge moisture and the like in the ground.

  The first embankment layer 3 piled up on the soft ground 2 serves as a scaffold for a driving machine or the like that performs consolidation on the soft ground 2 and places the vertical drain material 10 into the soft ground 2. It is a layer formed by depositing ordinary soil. Moreover, the 2nd embankment layer 4 heaped so that the horizontal drain material 20 may be covered seals the soft ground 2, and is formed by embedding normal soil like the 1st embankment layer 3. Layer.

  As shown in FIGS. 4 and 5, the vertical drain member 10 includes a long outer wall 11 and a hollow portion 12 formed by being surrounded by the outer wall 11. The outer wall 11 of the vertical drain material 10 is formed from a water permeable member having water permeability. As shown in FIG. 5A, the outer wall 11 of the vertical drain member 10 is formed so that the cross-sectional area of the hollow portion 12 decreases from the upper end 11b to the lower end 11a. This is based on the assumption that the drainage capacity on the upstream side, that is, the lower end 11a side of the outer wall 11, and the drainage capacity on the downstream side, that is, the upper end 11b side of the outer wall 11, are different, and that the downstream side has a larger drainage flow rate. Thus, material costs can be saved. Specifically, as shown in FIG. 5A, the outer wall 11 of the vertical drain material 10 has a relationship in which the thickness S1 at the upper end 11b and the thickness S2 at the lower end 11a satisfy S1> S2, The thickness is formed to be S2 for a while from S1.

  As described above, the outer wall 11 of the vertical drain member 10 is not limited to be formed such that the cross-sectional area of the hollow portion 12 gradually decreases from the upper end 11b to the lower end 11a. For example, FIG. As shown in FIG. 3, the cross-sectional area of the hollow portion 12 may be formed so as to decrease stepwise from the upper end 11b to the lower end 11a. Specifically, the vertical drain member 40 shown in FIG. 5B is formed by connecting outer walls 41, 42, 43, and 44 having different thicknesses. Each outer wall 41-44 has thickness of S3-S6, respectively, and the thickness is formed in S3> S4> S5> S6. In addition, the vertical drain member 40, for example, abuts the end portions of the outer wall 41 and the outer wall 42 and is connected by an adhesive tape 45. Similarly, the vertical drain member 40 is formed by abutting adjacent outer walls and connecting them with an adhesive tape 45. The vertical drain member 40 is formed by connecting outer walls 41 to 44 having a predetermined length from the upper end 40b to the lower end 40a so that the thickness gradually decreases. In addition, although the vertical drain material 40 is formed by connecting the four outer walls 41-44 in FIG.5 (B), not only this but a multistage connection, the cross-sectional area of the hollow part 12 is the same. Any material can be used as long as it is formed so as to be gradually reduced. In addition, the vertical drain member 40 is described as being connected by the adhesive tape 45, but is not limited thereto, and may be formed by being connected by a binding tool such as an adhesive or a staple. Furthermore, it is preferable that the adhesive tape 45 used for the vertical drain material 40 is a thing which has many water-permeable holes intermittently so that it may have water permeability. Furthermore, although the vertical drain material 40 described each abutting each outer wall 41-44 and connecting with the adhesive tape 45, you may make it project the edge part of the other outer wall to the edge part of one outer wall. .

  Further, the outer wall 11 of the vertical drain material 10 has a substantially rectangular cross section, and a hollow portion 12 is formed inside by the outer wall 11. The vertical drain material 10 is placed at a predetermined depth in the soft ground 2 and is disposed so that the upper end 11b faces the ground surface 2a of the soft ground 2 for a predetermined length. Since the outer wall 11 has water permeability, the vertical drain material 10 is arranged vertically on the soft ground 2 in order to improve the soft ground by discharging moisture in the soft ground 2. As shown in FIGS. 2 and 3, a plurality of vertical drain members 10 are arranged on the soft ground 2 at intervals of 1 m, for example, and the upper end 11b of each outer wall 11 is connected to the horizontal drain member 20, and this horizontal drain member Through 20, the moisture in the soft ground 2 is discharged.

  As shown in FIG. 4, the outer wall 11 of the vertical drain material 10 is made of a water-permeable material, and the outer wall 11 provides a hollow portion 12. In the hollow portion 12, a core material 13 having a certain degree of flexibility and shape retention is provided. The outer wall 11 has a substantially rectangular cross section, and moisture in the soft ground 2 is passed through the hollow portion 12 formed by the gap between the outer wall 11 and the core material 13.

  The core material 13 of the vertical drain material 10 has a number of grooves in the longitudinal direction, and the grooves serve as a water passage for water that has permeated the outer wall 11 in the soft ground 2. The core member 13 has a certain degree of flexibility in consideration of convenience such as followability / stretchability and transportation due to ground subsidence in ground improvement, and has a sufficient water passage after being placed on the soft ground 2. For example, it is formed from a resin material such as plastic having shape retention. The core material 13 is formed from materials, such as vinyl chloride and polyethylene, for example. Further, the core material 13 is formed in accordance with the shape of the outer wall 11, that is, the outer wall 11 is formed so that the cross-sectional area of the hollow portion 12 decreases from the upper end 11b to the lower end 11a. The number of grooves in the width direction is reduced, or the height of the grooves in the height direction is reduced.

  In addition, the core material 13 is not limited to the above, and flexibility in consideration of the subsidence / stretchability due to the settlement of the ground in ground improvement, and the shape retaining property capable of ensuring the hollow portion 12 serving as a water passage. As long as it has, it may be made of any material and shape. In addition, the core material 13 is not limited to the above, and can be made environmentally friendly by being formed of a biodegradable resin material.

  The outer wall 11 is formed of a material having water permeability, and is formed so as to cover the outer periphery of the core member 13 leaving the hollow portion 12. The outer wall 11 is formed of, for example, a polyester non-woven fabric, allows moisture in the soft ground 2 to permeate through the hollow portion 12, and allows the permeated moisture to pass through the horizontal drain material 20 to be discharged. The outer wall 11 is made of a biodegradable resin material in the same manner as the core material 13, so that it is environmentally friendly even when the entire vertical drain material 10 is left in the ground. it can.

  A plurality of such vertical drain members 10 are placed vertically at a predetermined interval on the soft ground 2 using a known placement device. The vertical drain material 10 is placed at a predetermined position by, for example, winding an anchor (not shown) around the lower end. At that time, by making the lower end portion of the vertical drain material 10 in a folded state, it is possible to prevent the entry of sand or the like from the lower end.

  The vertical drain material 10 is formed by, for example, forming the core material 13 by extrusion molding while continuously changing the height or width, and covering the nonwoven material that becomes the outer wall 11. The vertical drain material 10 formed in this way is wound in a roll shape at a manufacturing factory or the like and installed in a driving device.

  Next, the horizontal drain material 20 will be described.

  As shown in FIGS. 6 and 7, the horizontal drain member 20 includes a long outer wall 21 and a hollow portion 22 formed by being surrounded by the outer wall 21. The outer wall 21 of the horizontal drain material 20 is a drainage member that drains water from the vertical drain material 10 to the outside of the soft ground 2, and is formed of a material having water permeability similar to that of the vertical drain material 10. As shown in FIG. 7A, the outer wall 21 of the horizontal drain member 20 is formed so that the cross-sectional area of the hollow portion 22 decreases from the downstream end 21b to the upstream end 21a. This is similar to the vertical drain material 10, assuming that the drainage capacity on the upstream side is different from the drainage capacity on the downstream side, and the flow rate of drainage is higher on the downstream side. Cost savings can be made. Specifically, as shown in FIG. 7A, the outer wall 21 of the horizontal drain member 20 has a width T1 at the downstream end 21b and a width T2 at the upstream end 21a such that T1> T2. There is a relationship, and the width is formed to be T2 for a while from T1. In addition, the horizontal drain member 20 is closed at the upstream end portion 21a by turning back the end portion with a heavy stone, staple, or the like (not shown) to prevent drainage from flowing out from the upstream end portion 21a.

  As described above, the outer wall 21 of the horizontal drain member 20 is not limited to be formed so that the cross-sectional area of the hollow portion 22 gradually decreases from the downstream end 21b to the upstream end 21a. As shown in FIG. 7B, the cross-sectional area of the hollow portion 22 may be formed so as to gradually decrease from the downstream end portion 21b to the upstream end portion 21a. Specifically, the horizontal drain material 50 shown in FIG. 7B is formed by connecting outer walls 51, 52, 53, 54 having different widths. Each outer wall 51-54 has the width | variety of T3-T6, respectively, and the width | variety is formed in T3> T4> T5> T6. Further, the horizontal drain member 50 is connected by pushing and fitting the end of the outer wall 52 to the end of the outer wall 51. Similarly, the horizontal drain member 50 is formed by connecting the end portions of the adjacent outer walls by pushing and fitting each other. The horizontal drain member 50 is formed by connecting outer walls 51 to 54 having a predetermined length from the downstream end 50b to the upstream end 50a so that the width gradually decreases. In addition, although the horizontal drain material 50 is formed by connecting the four outer walls 51 to 54 in FIG. 7B, the horizontal drain material 50 is not limited to this, and the cross-sectional area of the hollow portion 22 is connected in multiple stages. Any material can be used as long as it is formed so as to be gradually reduced. Further, the horizontal drain member 50 is not limited to being connected by pushing and fitting the respective outer walls, and may be connected by, for example, the adhesive tape 45 used in the vertical drain member 40. Alternatively, they may be formed by being connected by a binding tool such as an adhesive or a staple.

  Further, the outer wall 21 of the horizontal drain material 20 has a substantially rectangular cross section, and the outer wall 21 forms a hollow portion 22 inside. As shown in FIG. 3, the horizontal drain member 20 is placed on the outer wall 21 at the upper end of the vertical drain member 10 exposed from the soft ground 2. As shown in FIGS. 2 and 3, the horizontal drain material 20 is arranged along the vertical drain material 10 arranged in a straight line, and the upper end of the vertical drain material 10 is placed on the outer wall 21. The drainage from the vertical drain material 10 flows into the horizontal drain material 20 and is finally discharged out of the soft ground 2.

  The vertical drain material 10 and the horizontal drain material 20 are not limited to the upper end of the vertical drain material 10 placed on the outer wall 21 of the horizontal drain material 20 as described above, and are connected using a well-known connecting member. It may also be possible to place a heavy stone such as a sandbag and maintain the mounting state. Furthermore, an opening may be provided in the outer wall 21 of the horizontal drain material 20, and the upper end of the vertical drain material 10 may be inserted to ensure water flow.

  As shown in FIG. 6, the outer wall 21 of the horizontal drain member 20 is made of a water permeable material, and the outer wall 21 provides a hollow portion 22. In the hollow portion 22, a core member 23 having a certain degree of flexibility and shape retention is provided. The outer wall 21 has a substantially rectangular cross section, and moisture in the soft ground 2 is passed through the hollow portion 22 formed by a gap between the outer wall 21 and the core member 23.

  The core material 23 of the horizontal drain material 20 is embossed to form unevenness on the plate-like member, and the gap formed by the unevenness becomes the hollow portion 22. The horizontal drain material 20 discharges moisture from the vertical drain material 10 to the outside of the soft ground 2 through this gap. The core material 23 has a certain degree of flexibility in consideration of convenience such as followability / stretchability and transportation due to ground subsidence in the ground improvement, similar to the core material 13 used for the vertical drain material 10, It is formed from a resin material such as plastic having shape retaining properties for securing the hollow portion 22 that becomes a water passage for moisture from the vertical drain material 10. The core material 23 is made of a material such as vinyl chloride or polyethylene. Further, the core member 23 is formed in accordance with the shape of the outer wall 21, that is, the outer wall 21 is formed so that the cross-sectional area of the hollow portion 22 decreases from the downstream end portion 21b to the upstream end portion 21a. Accordingly, the core material 23 is formed to have a small width.

  In addition, the core material 23 is not limited to the above, and flexibility in consideration of the subsidence / stretchability due to ground subsidence in ground improvement, and the shape retaining property that can secure the hollow portion 22 serving as a water passage. As long as it has, it may be made of any material and shape. The core material 23 is not limited to the above, and can be made environmentally friendly by being formed of a biodegradable resin material.

  The outer wall 21 is formed from a material having water permeability, and is formed so as to cover the outer periphery of the core member 23 leaving the hollow portion 22. The outer wall 21 is formed of, for example, a polyester non-woven fabric, allows moisture from the vertical drain material 10 to permeate through the hollow portion 22 and discharges the permeated moisture. The horizontal drain member 20 is not limited to the above, and the outer wall 21 may be formed of a water-impermeable material made of vinyl chloride. Furthermore, the outer wall 21 can be made environmentally friendly by forming it with a biodegradable resin material, like the core material 23.

  As described above, the vertical drain member 10 and the horizontal drain member 20 are not limited to changing only one of the thickness and width in a temporary or stepwise manner, and the thickness and width are changed in a temporary or stepwise manner. May be.

  In the ground improvement device 1 having the above-described configuration, moisture and the like in the ground pass through the outer wall 11 of the vertical drain material 10 by the consolidation action of the first embankment layer 3 and the second embankment layer 4, It flows into the hollow part 12, flows into the hollow part 22 of the horizontal drain material 20 through this hollow part 12, and is drained. Each of the drain members 10 and 20 is formed so that the cross-sectional area decreases from one end to the other end, and the other end side is disposed upstream and the one end side is disposed downstream. For this reason, each drain material 10 and 20 has the shape according to the drainage capacity in each position, and can reduce material cost. Moreover, since each drain material 10 and 20 has a cross-sectional area according to a flow volume, it can drain efficiently.

  In addition, although the ground improvement apparatus 1 installs the vertical drain material 10 and the horizontal drain material 20, and is used for the ground improvement construction method by the compaction by the embankment layer 4, it does not restrict to this but decompresses to the horizontal drain material 20. Of course, it may be used in a ground improvement method in which a pump as means is connected and a negative pressure is applied to the ground by the action of the pump.

  Next, another embodiment of the ground improvement device 1 will be described. In addition, about the structure same as the ground improvement apparatus 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted. As shown in FIG. 8, the ground improvement device 60 shown as the second embodiment includes a vertical drain material 70 placed in a soft ground 2 facing a predetermined length of the ground surface 2a, and a ground surface 2a. It is composed of a sand mat layer 61 stacked on top, a sealing sheet 62 covered on the sand mat layer 61, and a drainage pump 63 that sucks out moisture in the sand mat layer 61.

  The ground improvement device 60 is a vertical drain material in which the soft ground 2 is consolidated by a sealing sheet 62 covered on the soft ground 2 and is placed on the soft ground 2 at a predetermined depth, for example, 30 to 50 [m]. 70, the moisture, air, etc. in the ground flows in the direction indicated by the arrow A in FIG. 8, that is, toward the ground surface 2a, and the moisture, etc. that has flowed into the sand mat layer 61 is discharged by the drain pump 63. It is a device that improves.

  The sand mat layer 61 is formed of sand or the like having good water permeability, and allows water or the like from the vertical drain material 70 to flow through the drainage pump 63.

  The sealing sheet 62 is a sheet made of a water-impermeable member for covering the soft ground 2 including the sand mat layer 61 and compacting the soft ground 2. As shown in FIG. 8, the end portion of the sealing sheet 62 is embedded in the ground in order to enhance the compactness.

  The vertical drain material 70 has the same configuration as that of the vertical drain material 10, and includes a long outer wall 71 and a hollow portion 72 formed by being surrounded by the outer wall 71 as shown in FIG. 9. The outer wall 71 of the vertical drain material 70 is formed from a water permeable member having water permeability. As shown in FIG. 9A, the outer wall 71 of the vertical drain member 70 is formed so that the cross-sectional area of the hollow portion 72 decreases from the upper end 71b to the lower end 71a. This is based on the assumption that the drainage capacity on the upstream side, that is, the lower end 71a side of the outer wall 71 is different from the drainage capacity on the downstream side, that is, the upper end 71b side of the outer wall 71, and that the drainage flow rate is higher on the downstream side. Thus, material costs can be saved. Specifically, as shown in FIG. 9A, the outer wall 71 of the vertical drain material 70 has a relationship in which the thickness S1 at the upper end 71b and the thickness S2 at the lower end 71a satisfy S1> S2, The thickness is formed to be S2 for a while from S1. Further, a water impermeable portion 73 is formed in the vertical drain material 70 over a predetermined distance from the upper end 71b. When the vertical drain material 70 is driven into the soft ground 2, the impermeable portion 73 has a predetermined depth, for example, 2 to 3 [m] from the ground surface 2 a as an impermeable layer, and an embankment layer is not provided. To fulfill the role of The impermeable portion in the vertical drain material is a member provided when a so-called atmospheric pressure method is used. The impermeable portion 73 in the vertical drain material 70 may be formed by winding an impermeable adhesive tape 74, or may be formed by applying an impermeable material.

  Note that the outer wall 71 of the vertical drain material 70 is not limited to be formed so that the cross-sectional area of the hollow portion 72 gradually decreases from the upper end 71b to the lower end 71a, as in the vertical drain material 10, for example, FIG. As shown to (B), you may form so that the cross-sectional area of a hollow part may become small in steps from an upper end to a lower end. In addition, the example of the vertical drain material in FIG. 9 (B) is not limited to abutting the end portions of the outer walls as in the vertical drain material 40 shown in FIG. 5 (B). What is connected by 45 is shown.

  In the ground improvement device 60 having the above-described configuration, due to the compacting action of the sealing sheet 62, moisture or the like in the ground passes through the outer wall 71 of the vertical drain material 70 and flows into the internal hollow portion 72. The water flows into the sand mat layer 61 through 72 and is drained by the drain pump 63. The vertical drain members 70 are formed so that the cross-sectional area decreases from one end to the other end, and the other end side is disposed upstream and the one end side is disposed downstream. For this reason, the vertical drain material 70 has a shape corresponding to the drainage capacity at each position, and can reduce the material cost. Moreover, since the vertical drain material 70 has a cross-sectional area corresponding to the flow rate, efficient drainage can be performed.

  In addition, although the example which provides the sand mat layer 61 was demonstrated in the ground improvement apparatus 60, you may make it provide a horizontal drain material similarly to the ground improvement apparatus 1 not only this.

  Moreover, in the ground improvement apparatuses 1 and 60, as shown in FIG. 10, you may make it install a horizontal drain material on the ground surface 2a so that it may become a grid | lattice form. At this time, since the horizontal drain material drains from the vicinity of the center of the soft ground 2 to the outside of the soft ground 2, as shown in FIG. 10, the cross-sectional area increases toward the outside of the soft ground 2. By arranging so as to be, wastewater treatment can be performed more efficiently. In addition, you may make it select such a horizontal drain material suitably according to the planar shape of the soft ground planned to improve, or the position which guides drainage.

It is sectional drawing which showed the outline of the ground improvement apparatus. It is the top view which showed the outline of the ground improvement apparatus. It is the perspective view which showed the connection of a vertical drain material and a horizontal drain material. It is the fracture | rupture perspective view which showed a part of vertical drain material. (A) is sectional drawing in the A-A 'line | wire of the vertical drain material of FIG. 4, (B) is sectional drawing shown as other embodiment of a vertical drain material. It is the fracture | rupture perspective view which showed a part of horizontal drain material. (A) is sectional drawing in the B-B 'line | wire of the horizontal drain material of FIG. 6, (B) is sectional drawing shown as other embodiment of a horizontal drain material. It is sectional drawing which showed the outline of the ground improvement apparatus shown as other embodiment. It is sectional drawing of the vertical drain material used for the ground improvement apparatus shown as other embodiment. It is the top view which showed the example of installation of a horizontal drain material.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,60 Ground improvement apparatus, 2 Soft ground, 2a Ground surface, 3rd 1st embankment layer, 4th 2nd embankment layer 10,40,70 Vertical drain material, 11, 21, 71 Outer wall, 12, 22, 72 Hollow part, 13, 23 Core material, 20, 50 Horizontal drain material, 45 Adhesive tape, 61 Sand mat layer, 62 Seal sheet, 63 Drain pump, 73 Impervious part, 74 Adhesive tape

Claims (3)

A long outer wall part or all of which has water permeability,
A hollow portion surrounded by the outer wall portion and serving as a flow path communicating in the longitudinal direction of the outer wall portion;
The drain material, wherein the outer wall portion has a sectional area of the hollow portion that decreases from one end portion to the other end portion in the longitudinal direction.   2. The drain material according to claim 1, wherein the outer wall portion has a cross-sectional area of the hollow portion that is gradually or gradually decreased from one end portion to the other end portion in the longitudinal direction. In the ground improvement device that drains the moisture in the ground and improves the ground,
A vertical part having a long outer wall part that is pierced in the ground and partially or entirely permeable, and a hollow part that is surrounded by the outer wall part and that is a flow path that communicates in the longitudinal direction of the outer wall part. Drain material,
An elongated outer wall portion that communicates with the hollow portion of the vertical drain material at one end of the vertical drain material, and a hollow portion that is surrounded by the outer wall portion and serves as a flow path that communicates in the longitudinal direction of the outer wall portion. A horizontal drain material having
The vertical drain material and / or the horizontal drain material is a ground improvement device in which each outer wall portion has a cross-sectional area of the hollow portion that decreases from one end portion to the other end portion in the longitudinal direction.

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