JP2000319872A - Underground intercepting-plate construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an underground intercepting-plate construction method in which high impervious performance is maintained stably even when there is the defective filling of a sealing material or even when external force such as vibrations is applied while an intercepting plate is driven easily and workability is improved. SOLUTION: The underground intercepting-plate construction method is composed of the first process, in which a pit is formed into a ground in specified depth and a low-strength impervious wall 5 having unconfined compressive strength of 0.1-1.0 kgf/cm2 is constructed in the pit 4, and the second process in which an intercepting plate 10 is driven into the low-strength impervious wall 5 and an impervious wall 20 having sandwich structure in which the low- strength impervious wall 5 pinches the intercepting plate 10 from both surfaces and an underside is built.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of constructing an underground cut-off plate for the purpose of preventing the spread of underground pollution caused by waste, and containing a regulating pond or a river embankment, for example.

[0002]

2. Description of the Related Art Conventionally, for the purpose of preventing the spread of underground pollution due to waste, and containing regulating ponds and river embankments,
When constructing an underground blocking wall, a method is generally employed in which a blocking plate such as a sheet pile or a water blocking board having an appropriate width is sequentially connected in the width direction under the ground.

[0003] A steel plate or a sheet made of a flexible synthetic resin, which exhibits rigidity even when the thickness is small, is mainly used as the blocking plate.
For example, as shown in FIG.
1.5 m, the sheet main body 11 having an effective length in which the plate length H varies depending on the driving depth, the lower gripping margin 18 when setting to the driving machine, and the engagement of both ends engaging with the adjacent blocking plate A barrier plate 10 having a part 12 is known.

As a method of sealing the engaging portion 12 of the blocking plate 10, there are a method using a water-expandable sealing material and a method using a joint grout. In the case of a water-swellable sealing material, as shown in FIG. 4, the engaging portion 12 is formed of an engaging male member 15 and an engaging female member 14 in which the sheet body 11 of the blocking plate is welded to the end of the sheet body 11. Connect by mating,
High watertightness is maintained by interposing a water-swellable sealing material 13 in a fitting gap between the engaging male member 15 and the engaging female member 14. On the other hand, in the case of the joint grout, although omitted in the drawing,
A gap formed in the engaging portion 12 of the sheet main body 11 of the blocking plate is filled with an impermeable grout containing cement, water, a bulking agent, a swelling agent, and the like to maintain high watertightness.

[0005]

However, in the engaging portion 12 of the shut-off plate 10, there is a rare case where a defective filling of the sealing material or the joint grout may occur. In addition, damage may occur over time due to unexpected external force such as vibration. In such a case, water may leak from the seal portion, and the blocking plate may not be able to maintain the desired water blocking. In addition, although the installation of the blocking plate is usually performed until a penetration portion is formed in the impermeable layer of the ground, there is a possibility that the landing of the blocking plate on the impermeable layer may be incomplete, and in this case, However, there is a problem that water leakage occurs.

Accordingly, it is an object of the present invention to stably maintain a high water blocking performance even when there is a defective filling of a sealing material and even when an external force such as vibration is applied, and to place a blocking plate. It is an object of the present invention to provide an underground barrier plate construction method which is easy to perform and is excellent in workability.

[0007]

Under such circumstances, the present inventors have made intensive studies and as a result, have previously replaced the ground on which the blocking plate is to be cast with a specific low-strength artificial clay or the like.
After that, if a continuous barrier plate is constructed in artificial clay by penetrating the barrier plate, it is easy to cast the barrier plate due to its low resistance and has excellent workability, and the surroundings of the barrier plate are wrapped with low-strength impermeable walls. In order to complete the present invention, it has been found that even if there is a defective filling of the sealing material, and that even if external force such as vibration is applied, it can stably maintain high water shielding performance even if there is a defective filling of the sealing material. Reached.

That is, in the first aspect, a groove is formed at a predetermined depth in the ground, and a uniaxial compressive strength of 0.1 to 0.1 is formed in the groove.
A first step of constructing a low-strength impermeable wall of 1.0 kgf / cm ² , placing a blocking plate in the low-strength impermeable wall, and the low-strength impermeable wall attaches the blocking plate from both sides and a lower surface; And a second step of constructing an impermeable wall having a sandwich structure to be sandwiched therebetween. By adopting such a configuration, (1) it is possible to always maintain a stable and high water impermeability regardless of the filling failure of the sealing material.
(2) Because it adopts a sandwich-like triple structure, it has a high ability to follow the ground and is resistant to shaking such as earthquakes.
(3) It is easy to penetrate into the low-strength ground (low resistance) and the workability is improved.

[0009] The second aspect of the present invention is characterized in that the construction of the low-strength impermeable wall is based on replacement of artificial clay by ground grooving or by stirring and mixing in situ. An underground barrier plate construction method according to claim 1 is provided. By adopting such a configuration, the same effects as those of the first aspect can be obtained. (4) In the case where the impermeable wall of the artificial clay is formed, if the excavated soil is effectively used, the waste treatment is eliminated.

[0010] In addition, the low-strength impermeable wall may be configured as follows.
The underground barrier plate construction method according to claim 1 or 2, wherein the underground barrier plate is constructed so that a root portion is formed in an impermeable layer of the ground. By adopting such a configuration, the same effects as those of claim 1 and claim 2 can be obtained,
(5) Even if the grout is not filled up to the tip of the rooting portion, the water barrier can be maintained, and the amount of grout used can be reduced.
Moreover, since the construction is easy, the cost can be reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An underground barrier plate construction method according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram illustrating a first step of the present embodiment,
(A) is a schematic diagram showing a preparation step, and (B), (C), and (D) showing a step of excavating the ground with an excavator to form a groove and constructing a water impermeable wall in the groove. FIGS. 2A and 2B are views for explaining a second step of the present embodiment, wherein FIG. 2A is a step of preparing a placement of a shielding plate, FIG. 2B is a step of penetrating a water impervious wall, and FIG. FIG. 3D is a schematic diagram showing an end and drawing start step, and FIG.

In FIG. 1A, an excavator 1 cuts a groove 4 having a predetermined depth in a ground 3, and a penetrating machine 2 that cuts the ground is hung on a suspension wire 8 of a crawler crane 1a. Has been lowered. In the groove of the ground in the first step, the groove 4 is formed at a predetermined position at a predetermined depth by the penetrating machine 2. The depth can be reduced to such an extent that it penetrates into the impermeable layer 7 of the ground. A low-strength impermeable wall, which will be described later, forms a root in the water-impermeable layer 7 of the ground. It is preferable in that the water barrier property can be maintained without filling with grout. The width of the groove 4 is usually about 30 to 5
0 cm.

Next, in the groove 4, the uniaxial compressive strength is 0.1
A low-strength impermeable wall 5 of 1.0 kgf / cm ² is constructed. The low-strength impermeable wall 5 is formed by replacing artificial clay with a ground groove or by mixing and stirring in situ. As a method of replacing the artificial clay, a method of preparing an artificial clay by previously mixing cement and water with bentonite or locally generated clay, and injecting the artificial clay into the groove 4 may be used. Of these, the use of artificial clay consisting of locally generated clay, cement and water makes it possible to effectively use the soil generated by grooving and to reduce the cost in that the disposal of the discharged soil can be omitted.

As an example of mixing in situ at the in-situ, for example, a rod is rotated in accordance with the core of a column to which the tip of a mechanical stirrer is installed, and a low-strength solidified material is discharged from the tip of the apparatus. Rotate the stirring blade while mixing, excavate while mixing with excavated soil, stop discharging when reaching a predetermined depth, reverse the rod, pull up on the ground while mixing and stirring to form a columnar body A mechanical stirring method for constructing a wall-shaped impermeable wall 5 by connecting a large number of them, and an insertion pipe provided with an injection nozzle near the tip end penetrates into the ground, and lowers the injection nozzle while rotating the injection nozzle. A high-pressure jet jet method in which a solidified material is injected to form a cylindrical object, and a large number of the solid objects are connected to form a wall-shaped impermeable wall 5 may be used. This in-situ mixing and mixing is advantageous in that the groove and the impermeable wall can be constructed with the same device.

The low-strength impermeable wall 5 has a uniaxial compressive strength after solidification of 0.1 to 1.0 kgf / cm ² , preferably 0.3 to 0.8 kgf / cm ² .
kgf / cm ² . When the uniaxial compressive strength of the impermeable wall 5 is in this range, the workability is improved due to low resistance when the intercepting plate 10 is cast, and a sandwich shape formed by pouring the intercepting plate 10 is formed. The water impermeability wall can be stably maintained. Here, the unconfined compressive strength refers to the unconfined strength of the soil determined by the unconfined compression test method of the Japan Society of Geotechnical Engineers, "Soil unconfined compression test method (T511)".

As a grooving machine for grooving the ground in the first step or a piercing machine for grooving the ground and constructing a low-strength impermeable wall, known devices can be used, for example, an auger boring machine, Examples include a chain-type grooving machine and a mechanical stirring type solidification pile forming machine. These are appropriately selected according to the environmental conditions of construction and the properties of the construction ground.

In a second step of the present invention, a sandwiching plate is provided in the low-strength impermeable wall formed in the first step, and the low-strength impermeable wall sandwiches the blocking plate from both sides and a lower surface. Build impermeable walls of structure. The low-strength impermeable wall on which the blocking plate is cast has a uniaxial compressive strength after solidification within the above range, but may be in a semi-solid state or a solidified state at the time of setting.

As the shielding plate 10, a steel plate having a small thickness and showing rigidity or a sheet having relatively small rigidity or a sheet made of a flexible synthetic resin can be used. In addition, as a method of penetrating the blocking plate 10 into the low-strength impermeable wall 5, a known method is used. That is, for example, the barrier plate 10 having a relatively small rigidity such as a thin steel plate is replaced with the penetration frame 9 having a high rigidity by the penetration machine 6.
At the same time, it penetrates into the underground 3 ((A), (B) in FIG. 2), penetrates to a predetermined depth ((C) in FIG. 2), and raises the penetrating frame 9 leaving the blocking plate 10 (FIG. 2). ((D) in FIG. 2)
It is done by doing. The shielding plate 10 is in the low-strength impermeable wall 5,
It is erected at the center in the width direction, and its tip is a low-strength impermeable wall 5
It is better to be slightly above the lower end of. Thereby, the low-strength impermeable wall 5 sandwiches the blocking plate 10 from both sides and the lower surface,
The impermeable wall 20 having a sandwich structure in which a part 21 of the root cut portion is formed in the impermeable layer in the ground can be constructed. If such a water-impermeable wall 20 is constructed, it is possible to always maintain a stable and high water-shielding performance regardless of shaking due to an earthquake or the like irrespective of poor filling of the sealing material or the joint grout.

Examples of the method of placing the barrier plate 10 in the water impervious wall in the second step include a press-fit type penetration method and a penetration method using a high-frequency vibrator. It is appropriately selected according to the required construction environment and the nature of the construction ground.

[0020]

According to the first aspect of the present invention, it is possible to always maintain a stable and high water blocking performance irrespective of a poor filling of the sealing material. Since the impermeable wall has a sandwich-like triple structure, it has a high ability to follow the ground and is resistant to shaking such as an earthquake. In addition, penetration into low-strength ground is easy (low resistance), and workability is improved.

According to the second aspect of the present invention, the same effects as those of the first aspect can be obtained.
By effectively utilizing the grooving soil as a component of artificial clay,
The cost can be reduced because the disposal process can be omitted. According to the third aspect of the present invention, in addition to the same effects as those of the first and second aspects, the water barrier can be maintained without filling the joint grout up to the tip of the rooting portion, and the amount of grout used is reduced. Since it can be reduced and the construction is easy, the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a first step of an underground barrier plate construction method according to an embodiment of the present invention, wherein (A) is a preparation step,
(B), (C), (D) is a schematic diagram showing a process of forming a groove by digging the ground with an excavator and constructing a water impermeable wall in the groove.

FIGS. 2A and 2B are diagrams illustrating a second step of the present embodiment, wherein FIG. 2A is a step of preparing a placement of a blocking plate, FIG. 2B is a step of penetrating a low-strength impermeable wall, and FIG. FIG. 3D is a schematic diagram showing a step of completing penetration and a step of starting extraction, and FIG. 4D shows a step of constructing an impermeable wall having a sandwich structure.

FIG. 3 is a front view in which a part of a blocking plate is cut away.

FIG. 4 is a partial perspective view showing a connection part of the blocking plate of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Excavator 1a Crawler crane 2, 6 Penetration machine 3 Ground 4 Groove 5 Low-strength impermeable wall 7 Impermeable layer 9 Penetration frame 10 Shielding plate 11 Sheet main body part 12 Engagement part 13 Water swellable sealing material 20 Sandwich structure Permeable wall

Continued on the front page (72) Inventor Tomohisa Izushi 2-11-16 Hakata-ekimae, Hakata-ku, Fukuoka Prefecture Inside Fudo Construction Co., Ltd. (72) Inventor Kenji Harada 1-2-1 Taito, Taito-ku, Tokyo Fudo Construction Co., Ltd. In-house F term (reference) 2D049 EA01 FB02 FB03 FB11 FB20 GA17 GB05 GC11 GE02 GE10 GE20

Claims (3)

[Claims] A first step of forming a groove in the ground at a predetermined depth and constructing a low-strength impermeable wall having a uniaxial compressive strength of 0.1 to 1.0 kgf / cm ^{2 in} the groove; A second step of placing a blocking plate in the low-strength impermeable wall, and forming the impermeable wall having a sandwich structure in which the low-strength impermeable wall sandwiches the blocking plate from both sides and a lower surface. Underground cut-off board construction method. 2. The method according to claim 1, wherein the construction of the low-strength impermeable wall is based on replacement of artificial clay by ground grooving, or by stirring and mixing in situ. Underground barrier plate construction method. 3. The underground barrier plate construction method according to claim 1, wherein the low-strength impermeable wall is constructed so that a root is formed in an impermeable layer of the ground.