JP2528743B2 - Ground improvement method and drain device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving soft ground such as soft cohesive ground containing pore water, and a drain device used for the method.

[0002]

2. Description of the Related Art A sand drain method has been widely used as a method for improving soft ground. This method is
As shown in FIG. 9 , a large number of sand pillars B are vertically driven on the soft ground A to guide the groundwater (hereinafter referred to as pore water) contained in the soft ground between the particles of the sand pillar, The interstitial water is discharged to the side of the sand mat C laid on the ground surface through the interstices of the sand particles to reduce the interstitial water in the soft ground.

Further, as other soft ground improvement methods, there are a paper drain method and a plastic board drain method, and these methods are formed by a paper or a plastic material having a gap corresponding to the gap between the sand particles of the sand pillar. It is a method of driving ponds into the ground to reduce pore water.

[0004]

However, in any of the above methods, in order to discharge the pore water in the soft ground to the ground surface through the drain material having many pores such as sand particles and paper, the pore water pressure is increased. Therefore, it is necessary to place a large amount of loading embankment D such as earth and sand on the soft ground.

Then, by loading such soil or the like, the soft ground is consolidated to increase the pore water pressure in the ground, and the pore water is permeated into the gap of the drain material and discharged to the surface side as described above. However, this drainage action is performed because the pore water pressure in the soft ground due to the applied load is higher than the pore water pressure (natural head) that permeates into the gap of the drain material, and it is necessary to improve the drainage capacity. Must increase the water pressure difference.

For this reason, normally, embankment reaching a height of 5 to 10 m is carried out. However, if the necessary amount of embankment is constructed all at once, the soft ground will cause lateral flow and slip due to its large load, and its movement Since there is a risk that the drain material will be cut at the middle part and a discontinuous portion will be generated, it is necessary to carry out loading embankment in stages to gradually settle the soft ground.

[0007] Therefore, after the soil improvement strength is obtained by consolidation according to the loading embankment, the next step of embankment must be carried out and consolidation subsidence must be carried out again, and this work must be repeated, so that the construction management becomes complicated. However, in view of the fact that a long construction period is inevitably required, and the construction and removal of the embankment occupies most of the total construction cost, increasing the embankment volume poses problems in terms of workability and economy. there were.

For this reason, JP-A-49-82115
Non-perforated pipe inside perforated pipe body, as described in
Insert the body and suck the inside of the non-perforated pipe with a vacuum pump
Vacuum suction force inside the perforated pipe through the non-perforated pipe
Generated, and the suction force sucks and eliminates pore water
Although a device configured as in
The problem that the dehydration efficiency is poor due to the small contact area between the ground and the ground
In addition, there is a problem, and the perforated pipe body is grounded at the time of construction.
After embedding it in the board, the non-perforated pipe body is placed in the perforated pipe body.
Since it is inserted and integrated, workability may deteriorate.
Becomes Also, the upper end of the perforated pipe body is sealed by a seal.
Due to the fact that it is closed, there is normally no pore water inside the non-perforated pipe.
Cannot be raised and the pore water rises due to the vacuum suction force.
To do this, supply water from the ground side into the perforated pipe body or empty it.
It is necessary to supply energy.

The present invention has been made in view of the above problems, and by actively draining the water in the drain material to eliminate the natural head of the drain material, a large amount of embankment cannot be carried out. An object of the present invention is to provide a ground improvement method for efficiently improving the ground by relatively increasing the pore water pressure in soft ground and a drain device for carrying out the method.

[0010]

In order to achieve the above object, the ground improvement method of the present invention has a non-perforated pipe body having an open upper end and a large number of water passage holes on the contact surface with the ground. A plurality of perforated pipe bodies that are provided and open at the upper end are arranged in parallel
And the lower end of each perforated pipe body as described above.
A drain material is formed by communicating with the lower end of the non-perforated pipe body,
A large number of this drain material at regular intervals in the plane direction,
Pouring water vertically to the desired depth in the ground, and pouring the pore water in the ground that has flowed into the perforated pipe body from the water passage small holes of the perforated pipe body of each drain material And one of the pipe bodies is opened upward from the ground surface, and is forcibly discharged to the ground surface side by suction or pressure through the upper end opening of the other pipe body. .

As a drain device for carrying out the above method, a non-perforated pipe body having an open upper end,
A large number of water passage holes are provided on the contact surface with the board and the upper end is open.
A plurality of perforated pipes that are installed in parallel in one body
In addition, the lower end of each perforated pipe body
A drain member is formed by communicating with the lower end, and one of the non-perforated pipe member and the perforated pipe member of the drain member is opened with the upper end opened upward from the ground surface and the other pipe member is opened. It is characterized in that a suction means or a pneumatic means is connected to and communicated with the upper end.

[0012]

[Operation] When a drain material that is a combination of a perforated pipe body and a non-perforated pipe body is placed in soft ground, the upper end opening of the pipe body communicates with the atmosphere side, so suction force is not generated in the pipe body. However, the pore water in the ground infiltrates into the perforated pipe body due to the groundwater pressure through a large number of water passage small holes of the perforated pipe body, and stays there. At this time, the multiple perforated pipe bodies
Since it is in contact with the ground, the dehydration efficiency of the ground is significantly improved.
It Then, a suction means composed of a vacuum generator such as a vacuum is connected to the upper end of the non-perforated pipe body through a pipe, and when the suction means is operated, the perforated pipe body and the non-perforated pipe body communicate with each other at their lower ends. In addition, since the upper end of the perforated pipe body is opened upward from the ground surface, air enters the perforated pipe body due to suction through the non-perforated pipe body, and atmospheric pressure and no A negative pressure is generated in the perforated pipe body, and due to this pressure difference, pore water retained in the perforated pipe body rises in the non-perforated pipe body and is sucked and discharged.
When the suction means is connected to and communicates with the upper end of the perforated pipe body, air is sent into the pipe through the non-perforated pipe body whose upper end is open to the ground surface according to the suction force. Pore water in the pipe is sucked and discharged.

Contrary to the suction means, a compressed air supply device consisting of a compressed air supply device is connected to the upper end of the non-perforated pipe body through a pipe to supply pressurized air into the non-perforated pipe body. In this case, in this case, the accumulated water in the perforated pipe body rises due to the compressed air, opens upward from the ground surface, and the inside is at atmospheric pressure from the upper end opening of the perforated pipe body to the ground surface. Drained to the side. A pneumatic means may be connected to and communicate with the upper end of the perforated pipe body. In this case, the accumulated water in the perforated pipe body is forcibly discharged upward through the non-perforated pipe body.

[0014]

EXAMPLE FIG. 1 shows a drain material 1 of the present invention.
Made of flexible synthetic resin material, thin steel plate, or thick cloth, with a thickness of 3 to 6 mm and a width of 70 to 100 mm
The length is long, and it is formed in a hollow oblong rectangular shape with a horizontal cross section of about 100 m. As shown in FIG. 2, the drain member 1 is formed into a plurality of pipe bodies by being divided into a plurality of parts in the width direction by vertical partition plates 4, 4, ... 4 having both ends integrally fixed to front and rear walls. There is. The pipe bodies 3 and 3 other than the central pipe body 2 are provided with a large number of slit-shaped water passage holes 5 at appropriate intervals in the longitudinal direction on the front and rear side wall surfaces of the drain member 1 forming these pipe bodies 3. 5 ... 5 are bored to form a perforated pipe body, and the central pipe body 2 is a non-perforated pipe body.

Further, filters 6 made of non-woven fabric are attached to the front and rear outer wall surfaces of the drain material 1, and a cap body 7 is attached to the lower end of the opening of the drain material 1.
The cap body 7 is formed in an inverted triangular shape in cross section, and as shown in FIG. 3, the front and rear end portions of the upper end surface thereof are horizontally projected outward from both side walls of the drain member 1.

As a mounting structure of the cap body 7 to the drain member 1, for example, as shown in FIG. 4, a horizontally elongated rectangular mounting frame portion 7a is provided on the upper end surface of the cap body 7 and the mounting frame portion 7a is projected. 7a is fixed to the outer wall surface of the drain material 1 at the lower end of the opening by an appropriate means such as a screw. At the open lower end of the drain member 1 closed by the upper end surface of the cap body 7, the lower ends of the central non-perforated pipe body 2 and the perforated pipe body 3 communicate with each other through a passage 8.

In order to drive the drain material 1 thus constructed on the soft ground A, for example, as shown in FIG. 5, the long drain material 1 is arranged in a wound state on the driving carriage 11. At the same time, the punching and sandwiching member 13 for the drain material 1 is mounted on the lead 12 vertically supported on the tip of the carriage 11 so as to be able to move up and down, and an appropriate length of the drain material 1 is pulled out and the sheave 14 at the upper end of the lead is inserted. As shown in FIG. 6, it is sandwiched by the sandwiching member 13, and the lower end of the sandwiching member 13 is brought into contact with the outer peripheral surface of the upper end of the cap body 7 protruding from the lower end of the drain member 1.

In this state, the holding member 13 is lowered along the lead 12 and driven to the desired depth of the soft ground A. Next, when the clamping force of the clamping member 13 is released and pulled up, the drain member 1 is prevented from rising together by the cap body 7 attached to the lower end of the drain member 1 and is maintained in a state of being vertically driven in the soft ground A, and is clamped. Only the member 13 is pulled up. afterwards,
The drain material 1 is cut at the lower end side of the holding member 13 so that the upper ends of both pipes 2 and 3 of the drain material 1 are opened upward from the ground surface.

At the time of driving the drain material 1 next time, the drain material 1 is pulled out through the sheave 14 in response to the driving of the drain material 1 having the predetermined length, and therefore the lower end of the opening cut as described above. After mounting the cap body 7 on the ground, it is placed on the soft ground A in the same manner as described above. By repeating this placing work, as shown in FIG. 7, a large number of drain members 1 are placed in the plane direction of the soft ground A at desired intervals.

Then, as shown in FIG. 8, drainage pipes 15 are connected to the open upper ends of the non-perforated pipe bodies 2 of the drain materials 1 that are open to the ground surface, and these drainage pipes 15 are placed at appropriate places on the ground. Connected to suction means 16 such as vacuum pump installed,
The drain device is configured to communicate with each other.

When the drain material 1 is placed in the soft ground A, the pore water in the ground passes through the filter 6 and flows into the perforated pipe body 3 through the large number of water passage small holes 5, and the drain material is discharged. 1
Stays in the lower part of the. At this time, when the soft ground A is sand ground, a bar pile is driven into the ground between the placed drain members 1 and 1 and the bar pile is vibrated to increase the horizontal pore water pressure. As a result, the efficiency of collecting pore water with respect to the drain material 1 can be improved.

Further, even in the case of the ground other than the sand ground, an inflatable bag body is placed in the ground between the drain members 1 and 1 in place of the bar pile, and the bag body is inflated. Can forcibly increase the pore water pressure in the horizontal direction.
Furthermore, it is not always necessary to carry out embankment on the ground surface, but because the ground will be consolidated and settled due to the removal of pore water, embankment 17 with a height corresponding to the amount of subsidence should be performed beforehand, and Thus, the soft ground may be subjected to vertical consolidation. Thereby, drainage from the soft ground on the surface layer side is effectively performed.

As described above, when the pore water is infiltrated into the lower portion of the drain material 1 and the suction means 16 is operated, the inside of the non-perforated pipe body 2 is exhausted to a negative pressure, while the perforated pipe is Since the upper end of the body 3 is opened upward from the ground surface and the inside is always at atmospheric pressure, the pressure difference between these causes the body material 3 to penetrate into the drain material 1, as shown in FIG.
The remaining pore water rises up the non-perforated pipe body 2 from the passage 8 and is discharged and removed via the suction means 16. The suction and removal of the interstitial water by the suction means 16 may be performed continuously or intermittently at appropriate intervals.

Although the vacuum force from the suction means 15 is applied to the non-perforated pipe body 2 in the above embodiment,
Connect the drain pipe 15 to the upper end opening of each perforated pipe body 3,
Water may be pumped through the perforated pipe body 3. In this case, the non-perforated pipe body 2 serves to send outside air into the drain material 1 according to its suction force.

Further, instead of the suction means 16, each drain material 1
A pneumatic means (not shown) such as a compressor is connected to the upper end of the opening of the non-perforated pipe body 2 via an air supply pipe, and the pressurized air means is used to eliminate the pore water that enters and stays in the drain material 1. Good.

That is, when compressed air is fed into the non-perforated pipe body 2, the pore water in the drain material 1 is pushed up through the perforated pipe body 3 communicating with the atmosphere, and the upper end of the perforated pipe body 3 is pushed up. It is discharged to the surface side through the opening.
Further, according to the drainage action in the drain material 1 by the compressed air, the water level drop in the soft ground A can be made larger than the drainage amount by the suction action. The pumping by the compressed air may be performed by connecting an air supply pipe to the upper end of the opening of the perforated pipe body 3, like the pumping means by the suction action.

In the above embodiment, the non-perforated pipe is used.
Center the body 2 and place multiple perforated pipe bodies 3 on both sides.
Although they were installed side by side as a unit, the non-perforated pipe body 2 was not always arranged in the center.
There is no need to install one non-perforated pipe body 2 and multiple
If the hole pipe body 3 and the hole pipe body 3 are integrally assembled in parallel.
Good. Further, as the perforated pipe body 3 having the filter 6 attached thereto, a large number of stretched narrow flat yarns formed by making fine cracks in the stretched direction of the synthetic resin stretched film or tearing the synthetic resin stretched film are arranged at small intervals. Formed in a cylindrical shape from a so-called split cloth material, in which a large number of fine rectangular fine pores are provided between stretched narrow flat yarns arranged in the vertical and horizontal directions by fusing each of them and welding the intersections You may.

In this case, if a plurality of reinforcing strips of polyethylene or the like are integrally welded to at least the longitudinal direction of the peripheral wall surface, the casting can be easily performed, and the size of the rectangular strip pores can be increased. It can also be used as a filter and water passage hole.

Further, the cap body 7 is attached to the lower end of the drain material 1, but when the drain material 1 is driven into the soft ground A and then the pore water accumulated therein is pumped, the opening lower end of the drain material 1 It is not necessary because a passage is naturally formed in the soil on the side by the pumping force.

[0030]

As described above, according to the present invention, a non-perforated pipe body is provided in soft ground and a large number of water-permeable small holes are formed in the contact surface with the ground.
Multiple perforated pipes with
And Da設the drain material made by setting, penetrates into the drain material through a plurality of water-passing pores of the organic hole pipe, the pore water of soft in the ground staying, the perforated pipe or nonporous pipe Since the upper end of one of the pipes is opened to the atmosphere, it is forcibly pumped and removed by suction or pressure in the other pipe, so the pore water that has infiltrated and stayed in the drain material remains in both pipes. The pressure difference can be surely raised, and the pore water pressure in the soft ground can be relatively increased to efficiently improve the ground without performing a large amount of embankment as in the conventional case.

Furthermore, a non-perforated pipe body and a plurality of perforated pies
And the body are installed side by side to form the drain material.
In the soft ground, a non-perforated pipe body and multiple perforated pipe bodies
And can be placed at the same time, which improves workability.
Not a scale but multiple perforated pipes are in contact with the ground
Therefore, the water absorption efficiency of pore water is improved and the ground is improved in a short period of time.
Is what you can do.

Further , in the conventional well-point method, it is necessary to constantly apply suction force into the pipe body to take in the pore water in the soft ground into the pipe body. However, in the present invention, the upper end of the pipe body is placed in the atmosphere. Since it is opened to the side, pore water can penetrate and stay in the pipe body through the small pores without exerting suction force in the pipe body. It is only necessary to apply suction force or pressing force from the upper end of the pipe body to eliminate the accumulated pore water only when the pipe body is in use, so it is possible to economically improve the ground without constantly using pumping power. .

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a drain material,

FIG. 2 is a cross sectional view thereof,

FIG. 3 is a vertical sectional side view of a cap body portion,

FIG. 4 is a cross-sectional view showing a pumped state by suction force,

FIG. 5 is a simplified side view of the drain material placing device,

FIG. 6 is a cross-sectional view of a sandwiching member sandwiching a drain member,

FIG. 7 is a plan view of a drain material placed in soft ground,

FIG. 8 is a simplified vertical sectional view showing a ground improvement state,

FIG. 9 is a simplified vertical sectional view showing a conventional example.

[Explanation of symbols]

 1 Drain material 2 Non-perforated pipe body 3 Perforated pipe body 5 Small water passage hole 6 Filter 7 Cap body 8 Passage 15 Drain pipe 16 Suction means

Claims (2)

(57) [Claims] And 1. A non-porous pipe body and the upper end is opened, and a plurality of perforated pipe body and an upper end provided with a large number of water passing the small holes in the contact surface with the ground is opened in a parallel state Arranged in one
In addition, the lower end of each perforated pipe body
A drain material is formed by communicating with the lower end, and a large number of this drain material are vertically placed at a fixed interval in the plane direction to a desired depth in the ground, and water is passed through the perforated pipe body of each drain material. Pore water in the ground that has flowed into the perforated pipe body from a small hole is opened in the state in which the upper end of one of the non-perforated puff body and the perforated puff body is opened upward from the ground surface. A ground improvement method characterized in that the pipe is forcedly discharged to the ground surface side by suction or air pressure through the upper end opening of the pipe body. 2. A non-perforated pipe body having an open upper end, and a ground
A large number of water passage holes are provided on the contact surface with the board and the upper end is open.
A plurality of perforated pipes that are installed in parallel in one body
In addition, the lower end of each perforated pipe body
A drain member is formed by communicating with the lower end, and one of the non-perforated pipe member and the perforated pipe member of the drain member is opened with the upper end opened upward from the ground surface and the other pipe member is opened. A drain device characterized in that a suction means or a pneumatic means is connected to and communicated with the upper end.