JP3138909B2 - Improved construction method for soft ground and its improved construction equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving a soft ground, which improves water into a hard ground by discharging water and air contained in the soft ground without replacing the soil, and an improved construction apparatus for the soft ground. More specifically, the present invention relates to a method for improving soft ground and an improved construction apparatus capable of efficiently and surely discharging water and air contained in soft ground.

2. Description of the Related Art
As a method for improving soft ground, there is a vertical drain method, which is typically exemplified by a sand drain method and a paper drain method. The sand drain method is
Numerous sand piles (artificial sand columns) are installed in the soft ground at appropriate intervals in the vertical direction, and water is extracted from the ground through these sand piles to promote the consolidation and strength of the ground. This is a method of improving the ground. on the other hand,
The paper drain method is for promoting the consolidation of soft ground, and a cardboard provided with a vertically continuous water passage hole in a band-shaped base paper having a thickness of about 3 mm and a width of about 100 mm is appropriately formed with a mandrel. Driving and installing at intervals,
The water in the ground is drained through this card board. However, vertical drain methods such as the sand drain method and the paper drain method are good at the beginning of the treatment, but when the degree of vacuum in the ground increases as the water removal proceeds, water There was no gap to become a passage, and there was a problem that drainage was not completed at last. Therefore, an improvement method shown in FIG. 8 has been proposed for the purpose of further improving drainage efficiency. This method, after creating a paper drain,
A perforated pipe 2 connected to a vacuum pump 3 is disposed horizontally at the upper end 1a of the card board 1 so as to be in contact with the card board 1, and the card board 1 and the perforated pipe 2 are covered with a sand layer 4. Yes, by making the upper surface of the ground A a negative pressure through the perforated pipe 2 connected to the vacuum pump 3, the pressure difference with the ground A is increased, and the water in the ground A is removed from the card board 1 and the perforated pipe 2.
It is designed to be drained through. However, the perforated pipe 2 connected to the vacuum pump 3 is only covered with the sand layer 4, and a sufficient negative pressure environment cannot be created on the upper surface of the ground A. The hole 5 of the perforated pipe 2 is made of sand or ground A
Clogging may occur due to earth and sand from the inside, and there is a problem that a water suction effect cannot be obtained due to a pressure difference to a deep portion of the ground A, and sufficient drainage may not be performed. In the case of the improvement method shown in the drawings, the ground A
In order to create a negative pressure environment on the upper surface, suction must be performed with a strong suction force, and since suction is continued until drainage in the ground A is completed, it is consumed to operate the vacuum pump 3. Electric power and light oil were also large, and the cost required to create a negative pressure environment on the ground surface was enormous. The present invention has been made in view of such circumstances, and provides an improved construction method for a soft ground capable of efficiently and surely discharging water and air contained in the soft ground, and an improved construction apparatus thereof. The purpose is to do so.

In order to achieve the above object, according to the first aspect of the present invention, a vertical drainage wall is formed in the ground by driving a drain material into the ground at a predetermined interval. And a step of disposing a water-permeable material connected to a vacuum pump horizontally so as to be in contact with the drain material upper end, and laminating a synthetic resin film together with the drain material upper end and the water-permeable material on the ground. a step of covering in an airtight sheet, an improved method comprising the step of creating a state of negative pressure to the ground top surface by operating the vacuum pump, before
By operating the vacuum pump intermittently,
Normal pressure and negative pressure are alternately created, and the ground
When transitioning from a normal state to a normal pressure state,
To improve the soft ground, which is characterized by
The gist of the According to the second aspect of the invention, the drain material is grounded.
By the pouring child at a predetermined interval in the board, in the ground
Forming a vertical drainage wall at the upper end of the drain material;
Material that is connected horizontally to the vacuum pump so that it contacts
Arranging the drain material upper end portion on the ground and
Airtight laminated synthetic resin film with water-permeable material
Covering with a sheet and operating the vacuum pump to ground
A process of creating a negative pressure state on the upper surface.
And that the drain material is made to vibrate.
The feature of this method is the characteristic soft ground improvement method. Claim
The invention described in Item 3 is the method in which the steel is cast at a predetermined interval in the ground.
The drain material to be contacted with the upper end of the drain material.
Water-permeable material arranged horizontally and connected to the water-permeable material
A vacuum pump, the upper end of the drain material and water flow through the ground.
Airtight laminated synthetic resin film covering with materials
An improved construction apparatus of soft ground composed of a sheet, before
By operating the vacuum pump intermittently,
Normal pressure and negative pressure are alternately created, and the ground
When transitioning from a normal state to a normal pressure state,
A soft pipeline characterized by providing a pipeline for feeding air
The outline of the system is to improve the weak ground. Claim 4
The invention of the present invention relates to a drain which is cast at predetermined intervals in the ground.
Horizontal so that it contacts the top of this drain material.
Material and a vacuum pump connected to the material
On the ground together with the upper end of the drain material and the water passage material.
Airtight sheet laminated with synthetic resin film covering
An improved construction device for soft ground, comprising:
Softness characterized by attaching a vibration generator to the material
The gist is an improved construction device for the ground.

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Function) In the method for improving soft ground according to claim 1, the method for improving the soft ground
The surface is made of synthetic resin together with the drain material
It is covered with an airtight sheet laminated with film
At the same time, the vacuum pump connected to the water
The ground surface is under negative pressure,
And the pore water pressure in the above. So
This pressure difference causes the drain material to enter the ground
Formed in the ground by casting at intervals
Intake water and the air in the ground through vertical drainage wall to the ground surface
It is coming out. Water and air on the ground surface
Horizontally arranged passages in contact with the upper end of the drain material
Now drains through the water (to the drainage tank)
ing. The ground surface is under negative pressure, and the pressure difference
When water and air in the ground are sucked out to the ground surface,
The ground, especially around the drain material, is between the particles that make up the ground.
The gap is narrowed, making it difficult for water and air to pass through. As a result,
The water and air remaining in the panel are sufficiently absorbed even by the pressure difference.
No more. Also, in this improved method, vacuum
Because the pump is operated intermittently,
The top surface of the board must be created alternately between normal pressure and negative pressure
become. When changing from negative pressure to normal pressure
Means that the air or water is absorbed by the pressure difference
become. For this reason, the ground should be filled with air.
Vibration caused by a large impact force due to
The gap between the particles constituting the ground around the drain material expands,
Water and air are easier to pass through. Furthermore, in this improved construction method
Changes from negative pressure to normal pressure on the ground surface
Sometimes the pressure difference allows air or water to enter
Instead, we tried to send air actively,
Impact on the ground, especially the
The gap between the particles that compose the ground around the
Water and air are easier to pass through. This results in a more effective
In addition to being able to extract water and air from the ground,
Top surface can be returned to normal pressure faster
Has become. According to the method for improving soft ground described in claim 2,
The top surface of the ground is
Covered with airtight sheet laminated with synthetic resin film
And the vacuum pump connected to the water
Vacuum is applied, the top surface of the ground is in a negative pressure state.
And there will be a difference from the pore water pressure in the ground.
become. And this pressure difference causes the drain material to
By casting at predetermined intervals in the ground,
Water and air in the ground pass through the created vertical drain wall
It is designed to be sucked out to the surface. Ground surface water
And the air is horizontal so that it contacts the top of the drain material.
Discharged (through drainage tank) through distributed water penetration material
It has become. In this improved method,
By vibrating the ground material, the ground, especially the drain material
The gap between the particles that make up the surrounding ground expands, allowing water and air to pass through.
Easier. The improved construction device for soft ground according to claim 3
If necessary, hit the drain material at predetermined intervals in the ground.
And place it horizontally so that it contacts the upper end of the drain material.
A water passing material is provided, and a vacuum pump is connected to the water passing material. Change
On the ground together with the upper end of the drain material and the water-permeable material.
Cover with an airtight sheet laminated with a synthetic resin film,
When the vacuum pump is operated in the condition of
And there is a difference with the pore water pressure in the ground.
Become so. And due to this pressure difference,
Water and air in the ground pass through the vertical drainage wall
Surface and water and air on the ground surface are drained.
Pass through the water-permeable material that is arranged horizontally so that it contacts the upper end.
(To the drain tank). Ma
In this improved construction equipment, the vacuum pump is intermittently
Because it is designed to operate, the ground surface
Negative pressure states are created alternately. Negative pressure
When the pressure changes from normal to normal pressure, the pressure difference
I like air and water. For this reason,
Large impact force due to the air getting into the ground
Acts and vibrates, so the ground, especially around the drain material
The gap between the particles that compose the ground expands, allowing water and air to pass easily
Become. Furthermore, in this improved construction equipment,
Due to the pipeline that sends air,
When the surface transitions from negative pressure to normal pressure,
The pressure difference not only allows air and water to enter, but also
Acts on the ground because the air is sent extremely
The impact force is also greater, and the ground, especially around the drain material
The gap between the particles that compose the ground expands more, and water and air
Becomes easier to pass. As a result,
Water and air can be sucked out, and the ground
It can be returned to normal pressure. The soft according to claim 4
In the improved construction equipment for weak ground, the specified spacing
Place the drain material at
Arrange the water-permeable material horizontally so that it comes into contact with
Connect an empty pump. Further, the drain member on end on ground
Laminate a synthetic resin film with
Cover with airtight sheet, and operate the vacuum pump in this state.
Then, the upper surface of the ground is in a negative pressure state and the gap in the ground
There will be a difference between the pressure and the water pressure. And this pressure
Due to the difference, the ground is drained through vertical drainage walls created in the ground.
Water and air in the board are sucked out to the ground surface,
Water and air are horizontal so that they contact the top of the drain material
Is discharged (through the drainage tank)
It has become so. Also in this improved construction equipment
Is the drain material vibrated by the vibration generator?
Between the particles that make up the ground, especially around the drain material
The gaps widen and the water and air pass easily. Hereinafter, the present invention
Drawing of the soft ground improvement method and soft ground improvement construction equipment
This will be described in detail according to the embodiment shown in FIG. Below
The improvement method for soft ground described in Item 1 and 2 is explained.
You. In the course of this explanation, the soft ground of claim 3 and 4
We will also explain about the improved construction equipment. This break
The good method is a process of forming a vertical drain wall in the ground,
Arranging the water-permeable material connected to the vacuum pump;
The process of loading the consolidation load by sand in the area where the water wall is formed
And the process of covering the ground with an airtight sheet and creating a vacuum pump.
To create a negative pressure state on the ground surface by moving
You. The process of creating a vertical drainage wall in the ground involves drain material
In the ground at predetermined intervals.
As the drain material, the conventionally used drain
Materials can be used. Among them, paper drain
The material was inserted into the mandrel 12 as shown in FIG.
Penetrates into the ground A in the state, and the paper drain material 11
Casting by pulling up the mandrel 12 while leaving it at A
Simplicity of casting work and less occurrence of clogging
It is preferred because it has a function as a reliable permeable material
In the present embodiment, in the conventional strip-shaped base paper,
The paper bets Bu lane in which a longitudinally continuous water passage holes
Adopted. The drain material 11 is inserted into the ground A at a predetermined interval.
The ground A is installed at a predetermined interval.
Vertical drainage walls will be created,
The water and air contained in the intervening ground are indicated by arrows in FIG.
On the ground A through the drain wall made of drain material 11
Sucked up to the surface and discharged from the drain material upper end 11a
Will be done. Next, the water passing material connected to the vacuum pump
Place. As shown in FIG.
a protrudes from the upper surface of the ground A. Pass water through this protruding part
The members 13 are arranged in parallel so as to be in contact with each other. Through
The water material 13 passes through a drain wall made of the drain material 11.
Water and air sucked up to the ground A
To the outside of the soft ground (or outside the improvement area)
It should be a moving route for This water-permeable material
13, water and air flow in the longitudinal direction of the water-permeable material 13.
Anything that has a function as a passage that can move
Good, but water and air from the ground side penetrate into the water-permeable material
Mouths, such as holes and slits, may cause sand or sediment in the ground.
Is blocked by water, etc.
Difficult to penetrate into the ground,
The passage is blocked by throat and water and air are
With a structure that is unlikely to be able to move in the direction
Is desirable. The water-permeable material 13 shown in FIG.
And the fiber sheet 15 laminated on both surfaces thereof
The water and air flow through the plastic net 14 and the fiber
Gap with the sheet 15 and the fiber gap constituting the fiber sheet
Used to penetrate and move through
However, using plastic nets
A fiber sheet laminated only on one side of the knette,
In the case shown in FIG. 3, the fiber sheet employs a nonwoven fabric,
In addition, a material using a woven or knitted material may be used.
The water-permeable material 13 has a length of, for example, 1 m to 2 m.
It is a scale-shaped material.
To be placed on the drain material upper end 11a
Is sequentially from a roll from one end side to the other end side of the ground A upper surface.
Unwinding and covering the entire surface of the ground A
it can. The water-permeable material 13 is located near the upper end 11a of the drain material.
It has a band shape with a width that can cover
To one end side along the drain material upper end 11a on the top surface of the ground A
To the other end, and the upper surface of the ground A
Alternatively, they can be arranged in a grid. This water-permeable material 13
Is connected to a vacuum pump 16 at one end. In FIG.
In the embodiment shown, the vacuum pump 16 is connected to one end of the water-permeable material 13.
It is not directly connected, but via a drain tank 17. I mean
Negative pressure from the vacuum pump 16 passes through the drain tank 17.
It is transmitted to the water material 13. And this
The action allows water and air in the ground to pass through the train material.
It enters the water material 13 and moves inside the water material 13 to drain.
This is to be discharged to the tank 17.
The performance and model of the vacuum pump 16 are not particularly limited.
It can maintain the surface of the ground A under negative pressure for a long time.
Anything is fine. In the drawing, the water is passed through the vacuum pump 16.
Connected to one end of material 13 but connected to both ends
Can also. Next, as shown in FIG.
An airtight seal is provided together with the drain material upper end 11a and the water-permeable material 13.
It is covered with a port 18. The airtight sheet 18 is made of synthetic resin.
Laminate synthetic resin film on sheet and fiber substrate surface
Thus, air cannot pass through. This feeling
The ground A is covered with the dense sheet 18 and the vacuum pump is
When the vacuum pump 16 is operated, the negative pressure from the vacuum pump 16 is drained.
It is transmitted to the water-permeable material 13 via the tank 17 and
The surface is in a negative pressure state, and is between the pore water pressure in the ground A
Will be different. And this pressure difference
The ground A through the vertical drainage wall created in the ground A
As shown by the arrow in FIG. 4, the water and air
And the water and air on the ground surface
Water-permeable material 1 arranged horizontally so as to be in contact with end 11a
3 to the drain tank 17.
The airtight sheet 18 and the water-permeable material 13 are integrally provided.
You can also go. In this case, the airtight sheet 18 is
The inside of the water-permeable material 13 provided integrally with the sheet 18 (ground
Side) so that it contacts the drain material upper end 11a.
By installing, the installation of the airtight sheet 18 and the
Can be arranged at one time, and transportation is one article
Can be handled as Vacuum pump 1
6 is operated intermittently. As shown in FIG.
The surface becomes negative pressure, and the pressure difference
When water and air are sucked into the ground A surface, the ground, especially
Around the drain material 11, there is a gap between the particles constituting the ground A.
It becomes narrow, making it difficult for water and air to pass through. As a result, ground A
The remaining water and air can be sufficiently absorbed by the pressure difference.
Will not be issued. Intermittent operation of the vacuum pump
In the upper surface of the ground A, the condition of normal pressure and negative pressure is alternately created.
Will be. Change from negative pressure to normal pressure
Sometimes, you'll love the air. others
The air in the ground A
The impact force at this time acts on the ground A and
The board A was rocked, and as a result, as shown in FIG.
In particular, the gap between the particles constituting the ground A around the drain material 11 is
Spreads out, making water and air easier to pass through. Therefore, vacuum port again
By operating the pump 16, the surface of the ground A is in normal pressure
From negative pressure to negative pressure,
Water and air in the ground A are sucked out. This
By operating the vacuum pump intermittently,
Water and air will be sucked out more efficiently. Also
By operating the vacuum pump intermittently, the ground A
When alternately creating normal pressure and negative pressure conditions,
A pipeline for feeding air is provided, and the ground
When changing from a normal state to a normal pressure state,
Not only do you like the air, but also through the pipeline
So that air is actively pumped. in this case
In addition, the impact force acting on the ground becomes larger,
In particular, the gap between the particles constituting the ground around the drain material is larger.
Spreads well, making water and air easier to pass through. As a result,
The water and air in the ground can be sucked out more effectively.
The ground surface can be quickly returned to normal pressure.
There is a merit that it. Another thing that shakes ground A
Means for generating vibration in the drain material 11
A method of attaching and attaching and vibrating the drain material 11
There is. Also in this case, the ground, especially around the drain material
The constituent particle gap widens, and water and air pass easily.
As the vibration generator, for example, the thickness direction of the drain material 11
Electrodes made of conductive plate such as iron or aluminum on both sides
(Not shown) and apply current to these
A field is generated, and the electrode is attracted and
What caused vibration by repeating departure
And the like. Also, as shown in FIG.
The embankment 20 can be formed on the airtight sheet 18. FIG.
In the embodiment shown in FIG.
embankment on the airtight sheet 18 covering with the a and the water-permeable material 13
20 on the airtight sheet 18.
Consolidation dewatering of the ground A is performed by the consolidation load of the embankment 20
Ri Na as, in cooperation with the suction by the pressure difference between the above
To promote the discharge of water and air in the ground A to the upper surface of the ground
Become so. That is, the embankment 20 is placed on the airtight sheet 18.
If this is done, water and air exist in the ground A at the beginning of evacuation.
And the consolidation load due to the embankment 20 is
The relatively shallow part that works on the water and raises the pore water pressure
(L1) works to move to the periphery of the embankment 20. Soft ground
The board is not only improved, but also its periphery is soft and low in strength.
No. From this, the effect of consolidation loading by embankment 20 is
It extends to the periphery of the embankment 20. Continued evacuation
The water and air in the ground A are sucked out by the
During A, the pressure is gradually reduced. Along with it
The relatively shallow part (L1) of board A is the periphery of embankment 20
Inward volume contraction occurs. Also, the pore water pressure of the ground A
Rises (consolidation advances), embankment loading weight with embankment 20
Works on the soil particles on the ground A, and the depth of the ground A (L
2) works even on soil particles, more effective and reliable
Water and air discharge, conversion to hard ground (stable ground)
Good things will be done. In this case, in the ground A
Is the pressure due to the consolidation load of the embankment 20
And rise once. However, drain material in ground A
11 is decompressed, the water in ground A
Air is quickly sucked out to the ground A surface,
The rise is to be resolved immediately. In addition, shown above
What is done is just an example, for example on drain material
The position of the end 11a and the water-permeable material 13 is shifted during construction.
In order to avoid this, such as providing a fixing means,
Free modification within the scope described in the claims
Can be.

According to the first aspect of the present invention, there is provided a method for improving soft ground,
For good construction equipment, operate the vacuum pump intermittently.
This creates a normal pressure and negative pressure state alternately on the ground surface
And the ground surface shifts from negative pressure to normal pressure.
When the air just enters due to the pressure difference
No, actively by the pipeline installed on the ground surface
Impact force acting on the ground because air was sent in
Become even larger, the ground Especially around the drain material
The constituent particle gaps are larger and the water and air are more
It becomes easier to pass. As a result, water and sky in the ground
The air can be sucked out and the upper surface of the ground can be pressed at normal pressure faster
Can be returned to the state. Soft ground according to claim 2
For improved construction methods and improved construction equipment, drain materials are shaken.
The ground, especially around the drain material,
The particle gaps that make up the air spread, making it easier for water and air to pass through.
You.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state where a drain material is cast in the ground.

FIG. 2 is a cross-sectional view showing a state in which a water-permeable material is arranged in parallel so as to contact an upper end portion of the drain material.

FIG. 3 is an enlarged sectional view of a main part showing a water-permeable material.

FIG. 4 is a cross-sectional view showing a state where the ground is covered with an airtight sheet together with an upper end portion of the drain material and a water-permeable material.

FIG. 5 is a schematic view showing the ground around the drain material after water and air are sucked out.

FIG. 6 By returning from a negative pressure state to a normal pressure state,
The schematic diagram which shows the state which expanded the particle | grain gap which comprises the ground around drain material.

FIG. 7 is a sectional view showing a state in which embankment is provided on an airtight sheet.

FIG. 8 is a sectional view showing a conventional soft ground improvement construction apparatus.

[Description of Signs] 11 ・ ・ ・ Drain material 13 ・ ・ ・ Water-permeable material 14 ・ ・ ・ Net 15 ・ ・ ・ Fiber sheet 16 ・ ・ ・ Vacuum pump 18 ・ ・ ・ Airtight sheet 19 ・ ・ ・ Sand 20 ・ ・ ・Embankment

Continuation of the front page (56) References JP-A-50-7309 (JP, A) JP-A 64-14415 (JP, A) JP-A-1-105581 (JP, A) JP-A-6-299535 (JP) , A) JP-A-50-88810 (JP, A) JP-A-58-62211 (JP, A) JP-B-46-7348 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB Name) E02D 3/10 E02D 3/00

Claims (4)

(57) [Claims] A step of forming a vertical drain wall in the ground by placing a drain material in the ground at a predetermined interval; and a horizontal vacuum pump so as to contact the upper end of the drain material. Arranging a water-permeable material connected to the ground, covering the ground with an airtight sheet laminated with a synthetic resin film together with the upper end of the drain material and the water-permeable material, and activating the vacuum pump to apply a negative pressure to the upper surface of the ground. an improved method comprising the states from the creating step, by operating the vacuum pump intermittently, soil top
A normal pressure and a negative state are alternately created, and the ground
When the state changes from normal to normal pressure,
An improved method of soft ground characterized by sending air. 2. Drain materials are placed in the ground at predetermined intervals.
Construction work to create a vertical drainage wall in the ground by casting
The horizontal direction so that it contacts the upper end of the drain material.
The process of arranging the water-permeable material connected to the vacuum pump and
Together with the drain material upper end and the water-permeable material.
Covering the film with a laminated airtight sheet;
Operate the vacuum pump to create a negative pressure state on the ground surface
An improved method comprising the steps of:
Improvement of soft ground characterized by vibrating
Construction method. 3. A door which is installed at predetermined intervals in the ground.
Make sure that the drain material is in contact with the upper end of the drain material.
A flat water-permeable material and a vacuum port connected to the water-permeable material
And the upper end of the drain material and the water-permeable material on the ground.
Airtight sheet laminated with synthetic resin film to cover
An improved construction device for soft ground consisting of By operating the vacuum pump intermittently,
A normal pressure and a negative state are alternately created, and the ground
When the state changes from normal to normal pressure,
It is characterized by having a pipeline for sending air
Improved construction equipment for soft ground. 4. A door which is installed at a predetermined interval in the ground.
Make sure that the drain material is in contact with the upper end of the drain material.
A flat water-permeable material and a vacuum port connected to the water-permeable material
And the upper end of the drain material and the water-permeable material on the ground.
Airtight sheet laminated with synthetic resin film to cover
An improved construction device for soft ground, comprising:
Characterized in that a vibration generator is attached to the
Improved construction equipment for weak ground.