JPH07116705B2 - Method and apparatus for improving sandy soft ground - 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 removing groundwater contained in sandy soft ground to the ground to improve the sandy soft ground, and an apparatus for carrying out the method.

[0002]

2. Description of the Related Art Soft sandy ground may be liquefied during an earthquake and groundwater existing between sand particles may be ejected onto the surface of the ground, causing the ground to sink and collapse a building. For this reason, as shown in FIG. 5
As shown in Fig. 4, a large number of gravel columns b are placed in the sandy soft ground a at appropriate intervals, and when a earthquake occurs, the large gaps between the gravel columns are used to quickly bring groundwater to the ground surface. I'm trying to get it out.

On the other hand, as a construction method for improving the soft ground in advance, the sand drain construction method has been widely adopted. In this method, a large number of sand pillars are placed vertically on the soft ground and a loading embankment such as earth and sand is provided on the surface of the ground to increase the groundwater pressure in the ground by the load of the embankment, and the soft ground between the sand pillar particles. The groundwater contained in the groundwater is guided and discharged through the gaps of sand particles to the side of the sand mat laid on the ground surface to consolidate the ground.

[0004]

However, according to the former method of removing groundwater by using the gravel pillar b, when a small-scale earthquake frequently occurs, the sand grains in the soft ground a penetrate into the gravel to cause clogging. When a large earthquake occurs due to the clogging, ground water may not be able to be discharged to the ground surface through the gravel of the gravel pillar b.

On the other hand, according to the latter sand lane method,
In order to discharge the groundwater in the soft ground to the surface of the earth through the sand column having the gaps of sand particles, the groundwater pressure must be increased, and for that purpose, a large amount of embankment such as earth and sand must be placed on the surface of the ground. I have to. And, in order to consolidate the soft ground and increase the pore water pressure in the ground by loading such earth and sand, the embankment reaching the height of 5 to 10 m is usually performed. When the construction is applied to the soft ground, the large load may cause lateral flow or slip, and the movement may cause the sand pillar to be cut at the middle part, resulting in discontinuity. The soft ground must be gradually subsided.

[0006] Therefore, after the soil is improved by the consolidation according to the loading embankment to improve the ground, it is necessary to perform the next stage of embankment and to perform consolidation subsidence again, and this work must be repeated. 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.

The present invention has been made in view of the above problems. The groundwater pressure is forcibly increased without virtue of loading embankment and vibration is applied to compact the sand ground, and discharge to the surface is also positive. It is an object of the present invention to provide a method for improving sandy soft ground and a device for implementing the method, which enables efficient improvement of the ground.

[0008]

In order to achieve the above object, a method for improving sandy soft ground according to the present invention is provided with a vertical direction inside.
There is a drainage passage in the upper part and a water supply chamber in the upper part and the lower end.
There are water storage chambers inside and the upper and lower end of these water supply chambers.
A large number of water supply holes and water supply holes leading to the water chamber and the water storage chamber are provided respectively.
At the same time, connect the lower end of the drainage passage to the water storage chamber, and
In addition, it penetrates the water supply chamber to the outside of the drainage passage and the water reservoir chamber.
Jill communication hole a provided comprising rigid pipe and Da設in sandy soft ground, and the water feed chamber giving vibration to the pipe
Water is supplied to the ground through the water supply hole and the suction force is continuously or intermittently generated in the drainage passage to generate groundwater in the sandy soft ground and the above water supply hole.
The water that permeates into the ground flows into the water reservoir inside the pipe.
Then, the water is drained from the upper end of the pipe body to the outside through the drainage passage.

As a device for carrying out the above method, a small-diameter drainage pipe having a drainage passage inside is arranged vertically.
The water supply chamber and the water reservoir are located in the upper and lower ends of the installed pipe body.
Each of the chambers is provided and the upper periphery and the lower end of the pipe body are provided.
Water supply holes and water passages around these water supply chambers and water reservoirs
Each of the holes is provided, and the above-mentioned supply is provided outside the small diameter drain pipe.
A communication hole that penetrates the water chamber and leads to the water reservoir is provided.
Connect the lower end of the small diameter drain pipe to the water reservoir and
Connect the upper end of the small diameter drain pipe to the suction pipe,
Connect the water supply pipe from the side and at the top of the pipe body
It has a structure provided with a vibrator mounting portion .

[0010]

After the pipe body having the above-mentioned structure is driven on the sandy soft ground, or when the pipe body is vibrated by a vibration generator during the driving, the vibration is applied to the sandy ground through the pipe body. It is transmitted, the sandy ground is compacted, and the groundwater pressure that causes the liquefaction phenomenon rises, and the bottom end of this pipe body is punctured.
Groundwater enters the water reservoir below through a large number of water holes.
To enter.

Further, when suction means composed of a vacuum generator such as vacuum is connected to the upper end of the opening of the drainage passage through a pipe and the suction means is operated, the groundwater flowing in and accumulating in the water reservoir moves upward. Suctioned and discharged. At this time, sand
Groundwater in soft and soft ground is immersed in the pipe body through the water passage hole.
While supplying water, supply water to the water supply chamber in the upper end of the pipe body.
When supplied, the water flows into the sandy soft ground through the water supply holes.
Ejects and permeates, and moves to the side of the water hole in the sandy soft ground
However, due to the osmotic pressure at that time, the sandy soft ground around the pipe body
After compacting the board, through the water passage hole with the groundwater, the pipe body
Is sucked into.

[0012]

EXAMPLE 1 1 is a pipe body made of a rigid pipe such as a long steel pipe having a constant diameter , and its lower end as shown in FIGS.
A large number of water passage holes 2 and water supply holes 22 communicating with the inside of the pipe are provided on the peripheral walls of a predetermined length portion in the upper portion and the upper portion , respectively.
In addition, the lower end is formed into a sharp end, and the lid 3 is attached to the upper end opening. Inside the lower end of this pipe body 1 ,
As shown in FIG. 2, a partition frame 4 made of a perforated plate is stretched to form a lower space portion of the partition frame 4 in a water reservoir chamber 5, and a small-diameter drain pipe 6 having no holes is vertically provided in the center of the interior. And the inside of this small-diameter drain pipe 6 is formed into a drainage passage 7, and the lower end of the opening of the drainage passage 7 is fixed to the partition frame 4 in a penetrating state to communicate with the water reservoir chamber 5, and the upper end of the opening is the lid body. It faces the lower surface of No. 3 in a facing state.

Also, the above-mentioned water passage hole 2 and water supply hole 22 are provided.
Feed water chamber with filter layer 8 at the lower end portion and the upper portion of the pipe body 1
25 are provided respectively. That is, fixing a partition plate 24 in the lower end inside of the pipe body 1 made of similarly perforated plate by presence of the desired length interval in the upper part of the partition frame 4 made from a perforated plate,
The filter layer 8 is provided between the partition frame 4 and the partition plate 24, and in the upper portion of the pipe body 1, there is no hole at a desired length in a length portion corresponding to the water supply hole 22. fixing a vertical partition plates 26 and 27, to form a feed water chamber 25 between these partition plates 26, 27. Reference numeral 23 is an air inflow hole formed at an appropriate position of the lid body 3. This lid 3 that are mounted exciter mounting portion 9 at its upper central. Furthermore, connecting the water supply pipe 28 through the lid 3 from the outside to the paper water chamber 25, which communicates. In the figure, 29 is an air communicating pipe to the vertical pipe and communicated with the feed water chamber 25, the outer pipe of a small diameter drainage tube 6
The inside of 1 is communicated with the atmosphere.

In order to drive the perforated pipe 1 constructed as described above on the sandy soft ground A, as shown in FIG. The head of the perforated pipe 1 is hung by a crane carriage (not shown) through the shaker 12, and the vibration generator 12 is operated so that its downward vibration force is larger than its upward vibration force. Drive vertically until it reaches a state where it protrudes appropriately.

Even during and after this driving,
When the vibration exciter 12 is operated, the sandy soft ground A is compacted by the vertical vibration force thereof, the groundwater pressure rises, and the groundwater exuded between the sand particles due to the liquefaction phenomenon occurs in the pipe body 1.
It passes through the filter layer 8 from the lower end water passage 2 and moves and stays at the lower water reservoir chamber 5 side.

The operation of placing the pipe body 1 is repeated on the sandy soft ground A to be improved vertically and horizontally at desired intervals, and penetrates the lid body 3 of each of the placed pipe bodies 1 to eject a small diameter.
After connecting one end of the suction pipe 13 to the upper end of the drainage passage 7 of the water pipe 6 and communicating it, and connecting the other end of the suction pipe 13 to the suction device 14 such as a vacuum pump as shown in FIG.
When the suction means 14 is operated to generate a vacuum suction force in the suction pipe 13, the groundwater staying in the lower end water reservoir chamber 5 of the pipe body 1 is sucked up through the drainage passage 7 of the small diameter drainage pipe 6, and the surface of the ground surface passes through the suction pipe 13. Discharged to the sandy soft ground
The ground water inside flows into the water passage 2 side of the pipe body 1 and is stored in the water reservoir chamber 5 in the lower end portion of the pipe body 1 through the filter layer 8.
Be done. The removal of groundwater by this suction may be performed continuously or intermittently at appropriate intervals.

Although such ground water may be removed during the driving of the pipe body 1, as shown in FIG. 4 , after the driving of a large number of pipe bodies 1, the suction device 14 is operated. Main suction pipe 15
Is connected to each of the suction pipes 13 through the branch pipes 16 which are arranged in correspondence with the plurality of pipe body rows, and the pipes are communicated with each other. In this case, the after casting of the pipe 1, any pie
As described above, the exciter 12 is mounted on the exciter mounting portion 9 of the pump body 1, and the exciter 12 is operated, as described above.
While improving the water collection efficiency by compacting the sandy ground,
Absorb and remove water.

[0018] On the other hand, pie through the water supply pipe 28 from the ground
Supplying water to supply the water chamber 25 in the upper part of the flop body 1 Then, the water flows out to the sandy soft in the ground A through the water supply hole 22 from the water supply chamber 25. At this time, as described above , since the water in the water reservoir chamber 5 is removed through the suction pipe 13 and the water pressure is lost,
The water flowing into the sandy soft ground A from the water supply hole 22 is
Becomes downward flow moving into water communicating hole 2 side as shown in FIG. 3 with shaking in the ground by the force, this with sandy soft ground A perforated pipe around the penetration force of the water is compacted The permeated water flows from the water passage 2 together with the groundwater.
It flows into the ilter layer 8 . At this time, the ground surface may be loaded with a low embankment 30.

In the above embodiment, the pipe body 1
The vacuum force from the suction device 14 is applied to the upper end of the small-diameter drainage pipe 6 inside to suck and discharge the groundwater accumulated in the water storage chamber 5.
In the pipe body 1, a compressed air pipe whose lower end faces the lower end of the drainage passage 7 of the drainage pipe 6 upward (not shown).
No.) is provided and the upper end of the compressed air pipe is penetrated through the lid body 3.
Te is connected to an external air supply pipe (not shown), connecting the flue 19 to the gas device, such as a compressor (not shown), made to communicate with, of act gas from gas device to the lower end of the drain passage 7 <br/> allowed may be forced out exhaust <br/> groundwater staying in the water reservoir 5 by Rukoto. Further, although the perforated pipe 1 having a circular cross section is used in the above-mentioned embodiment, a perforated pipe having a rectangular cross section may be adopted.

[0020]

According to the present invention as described above, according to the present invention, the upper inside
There is a drainage passage in the downward direction and a water supply room in the upper part.
A water reservoir inside the lower end, and
A large number of water supply holes and water passage holes leading to these water supply chamber and water reservoir
Each of them is installed and the lower end of the drainage passage is connected to the water storage chamber.
In addition, the water is passed through the water supply chamber outside the drainage passage.
The rigid pipe formed by providing a communication hole communicating with the reservoir and Da設in sandy soft ground, and on giving vibration to the pipe
While supplying water to the water supply chamber and supplying water into the ground from the water supply hole , the suction force is continuously or intermittently generated in the drainage passage to generate groundwater in the sandy soft ground and
The water that permeates into the ground through the water supply hole is stored in the water storage chamber of the pipe body.
To flow into the inside, the vibration since it is intended to drained out from the upper end of the pipe through the drain passage, a pipe body hitting under construction in sandy soft ground, or After Da設by exciter to the pipe body Given a, passing sandy soil is compacted to be able to raise the groundwater pressure, a large number of water passing holes provided let me forcibly cause liquefaction at a lower end portion of the pipe
Therefore, the groundwater can be efficiently flowed into the water storage chamber and can be forcibly discharged from the water storage chamber through the drainage passage.
You can

Furthermore, the above-mentioned passages provided at the lower end of the pipe body.
A method to let groundwater in sandy ground flow into a water reservoir from a water hole
Water supply to the water supply chamber in the upper end of the pipe body
Permeate and penetrate into the sandy soft ground through the holes, and the penetration
It is possible to move water downward by gravity to the water passage side.
The sand around the pipe body is created by the osmotic pressure caused by the movement.
Are those capable of compaction quality soft ground, therefore, the workability by shortening the ground improvement work period it is possible to make improvements sandy soft ground without a conventional large amount of loading embankment as It is possible to improve and economically form the improved ground.

[Brief description of drawings]

FIG. 1 is a simplified front view of a pipe body ,

FIG. 2 is a vertical sectional front view,

FIG. 3 is a simplified vertical cross-sectional side view showing the state of ground improvement.

FIG. 4 is a simplified flat view showing a state of piping after the pipe is placed.
Floor plan ,

FIG. 5 is a simplified vertical sectional view showing a conventional example .

[Explanation of symbols]

1 pipe 2 water passage holes 5 water reservoir 6 small diameter drain pipe 7 drain passage 9 exciter mounting portion 12 exciter 13 suction pipe 22 the water supply hole 25 water chamber A sandy soft ground

Claims (2)

[Claims] 1. A vertical drainage passage is provided inside.
In addition, a water supply chamber is provided in the upper part and a water storage chamber is provided in the lower end.
In addition, the upper and lower ends are connected to the water supply chamber and the water storage chamber.
A number of water supply holes and water supply holes are provided respectively, and
The lower end communicates with the water storage chamber, and further outside the drain passage.
Has a communication hole that penetrates the water supply chamber and leads to the water reservoir
A rigid pipe body was Da設in the sandy soft ground, this pipe
While vibrating the body and supplying water to the water supply chamber to supply water into the ground through the water supply holes, continuously or in the drainage passage.
Sandy soft ground by generating suction force intermittently
The groundwater inside and the water that permeates into the ground through the water supply holes
Flow into the water chamber of the pipe body and through the drainage passage
A method for improving sandy soft ground, characterized by draining water from the upper end of a pipe body . 2. A small-diameter drainage pipe having a drainage passage inside is vertically arranged.
Water in the upper and lower ends of the pipes arranged in the direction
A water chamber and a water reservoir are provided, and the upper part of the pipe is surrounded.
And the water supply leading to these water supply chambers and sump chambers around the lower end
Holes and water passages are provided respectively, and further outside the small diameter drain pipe.
A communication hole that penetrates the water supply chamber and leads to the water storage chamber.
When connecting the lower end of the small diameter drain pipe to the water reservoir,
Connect the upper end of this small-diameter drain pipe to the suction pipe, and
Connect the water supply pipe from the ground side to the room and pipe body
An apparatus for improving sandy soft ground, characterized in that a vibrating machine mounting portion is provided at the upper end of the .