JPH09151448A - Improvement construction method for weak ground and device for executing the improvement work - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and properly discharge water and the air contained in weak ground. SOLUTION: Drain members except the upper ends 11a thereof are driven into ground A at the preset intervals, and a vertical drain wall is thereby constructed in the ground A. Also, a water passage member 13 connected to a vacuum pump 16 is laid, so as to come in contact with the upper ends 11a of the drain members. In addition, the ground A is covered with an airtight sheet 18, together with the upper ends 11a of the drain members and the water passage member 13. Then, the vacuum pump 16 is operated to generate a vacuum state on the upper surface of the ground A.

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 and a method for improving the soft ground by discharging water and air contained in the soft ground without replacing soil. More specifically, the present invention relates to an improved construction method for soft ground and an improved construction device for efficiently and reliably discharging water and air contained in the soft ground.

[0002]

2. Description of the Related Art
As a method for improving soft ground, there is a vertical drain method, which is typified by a sand drain method and a per drain method. The sand drain method is
A large number of sand piles (artificial sand pillars) are installed in the vertical direction at appropriate intervals in the soft ground, and water in the ground is drained through this sand pile to promote consolidation and strength increase of the ground, and hard It is a method to improve to the ground.

On the other hand, the paper drain method is for promoting the consolidation of soft ground and has a thickness of 3 mm and a width of 1 mm.
A cardboard having continuous water passages in the longitudinal direction in a belt-shaped base paper of about 00 mm is driven and set by a mandrel at appropriate intervals, and water in the ground is drained through the cardboard.

However, in the vertical drain method such as the sand drain method or the per drain method, it is good at the beginning of the treatment, but if the degree of vacuum in the ground increases as the water drains, There was a problem that there was no gap to become a passage for water, and finally it was not drained.

Then, an improved construction method shown in FIG. 8 has been proposed for the purpose of further improving the drainage efficiency. This method
After forming the paper drain, a perforated pipe 2 horizontally connected to a vacuum pump 3 is arranged on the upper end portion 1a of the card board 1 so as to come into contact with the paper drain, and the card board 1 and the perforated pipe 2 are attached to the sand layer 4 The negative pressure is applied to the upper surface of the ground A through the perforated pipe 2 connected to the vacuum pump 3 to increase the difference between the pore water pressure in the ground A and the water in the ground A. The cardboard 1 and the perforated pipe 2 are used for draining.

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. In addition, the holes 5 of the perforated pipe 2 may be clogged with sand or soil from inside the ground A, and there is a problem that the effect of sucking out water due to the pressure difference to the deep part of the ground A cannot be obtained. There was a case where it was not possible to drain water.

In the case of the improved construction method shown in the drawings,
In order to operate the vacuum pump 3, it is necessary to suck with a strong suction force in order to create a negative pressure environment on the upper surface of the ground A, and moreover, the suction is continued until the drainage in the ground A is completed. Since much electricity and light oil are consumed, the cost required to create a negative pressure environment on the top surface of the ground is enormous.

The present invention has been made in view of the above circumstances, and an improved construction method for a soft ground and an improved construction apparatus therefor capable of efficiently and reliably discharging water and air contained in the soft ground. It is intended to provide.

[0009]

In order to achieve the above object, the invention according to claim 1 is to drive the drain material into the ground at a predetermined interval while leaving the upper end portion of the drain material in the ground. The process of constructing a vertical drainage wall, the process of arranging a water-passing member horizontally connected to a vacuum pump so as to come into contact with the upper end of the drain member, and the air-tightness on the ground together with the drain member upper end and the water-passing member The gist is a method for improving soft ground, which comprises a step of covering with a sheet and a step of operating the vacuum pump to create a negative pressure state on the upper surface of the ground.

The invention according to claim 2 has as its gist a method for improving soft ground, characterized by placing a consolidation load of sand on a vertical drainage wall area.

A third aspect of the present invention has as its gist a method for improving soft ground, which comprises embankment on an airtight sheet.

According to a fourth aspect of the present invention, any or all of the drain material, the water-permeable material and the airtight sheet used in each step are made of a biodegradable molding material. Was the gist.

A fifth aspect of the present invention has as its gist a method for improving soft ground, characterized in that the biodegradable molding material is mainly composed of a natural polymer.

The invention according to claim 6 further comprises the step of intermittently operating the vacuum pump to alternately create a normal pressure state and a negative pressure state on the upper surface of the ground, thereby improving the soft ground. Was the gist.

A seventh aspect of the present invention has as its gist a method for improving soft ground, characterized in that air is sent to the upper surface of the ground when the upper surface of the ground changes from a negative pressure state to a normal pressure state. did. The gist of the invention of claim 8 is to improve the method for improving soft ground, characterized in that the drain material is vibrated.

According to a ninth aspect of the present invention, the drain material is placed at a predetermined interval while leaving the upper end portion in the ground, and water is horizontally arranged so as to contact the upper end portion of the drain material. The gist is an improvement construction device for soft ground, which comprises a material, a vacuum pump connected to the water material, and an airtight sheet covering the ground with the drain material upper end and the water material.

A tenth aspect of the present invention has as its gist an apparatus for improving soft ground, characterized in that the water-permeable material comprises a net and a fiber sheet attached to the surface of the net.

The invention of claim 11 has as its gist an improvement construction device for soft ground, characterized in that the water-permeable material is integrally provided inside the airtight sheet.

The twelfth aspect of the invention has as its gist an apparatus for improving soft ground, characterized in that any or all of the drain material, the water-permeable material and the airtight sheet are made of a biodegradable molding material.

The thirteenth aspect of the present invention has as its gist an improvement construction device for soft ground, characterized in that the biodegradable molding material is mainly composed of a natural polymer.

The invention of claim 14 has as its gist an improvement construction device for soft ground, characterized in that a pipeline for sending air is provided on the upper surface of the ground.

The invention of claim 15 has as its gist an improvement construction device for soft ground, characterized in that a vibration generator is attached to a drain material.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

(Operation) In the method for improving soft ground according to claim 1, the top surface of the ground is covered with the airtight sheet together with the drain material upper end and the water-permeable material, and the vacuum pump connected to the water-permeable material is activated. As a result of the evacuation, the upper surface of the ground is in a negative pressure state, and there is a difference with the pore water pressure in the ground.

Due to this pressure difference, the drain material is placed in the ground at a predetermined interval while leaving the upper end portion, and water and air in the ground are passed through the vertical drainage wall formed in the ground. It is designed to be sucked out to the surface. Water and air on the ground surface are discharged (to a drain tank) through a water-permeable material arranged horizontally so as to come into contact with the upper end of the drain material.

In the method for improving soft ground according to a second aspect of the present invention, the consolidation loading load of sand is placed on the vertical drainage wall construction area, and the consolidation loading of the sand pressurizes the soil. It progresses at the same time as the suction due to the difference, and the water and air in the soft ground are efficiently discharged to the upper surface of the ground.

In the method for improving soft ground according to the third aspect, when the load for sand consolidation is not placed on the vertical drainage wall construction area, the load is applied by the embankment provided on the airtight sheet. Consolidation dehydration of the ground proceeds at the same time as suction due to the pressure difference, and water and air in the soft ground are efficiently discharged to the upper surface of the ground.

In the case where the sand consolidation load is placed on the vertical drainage wall area, the sand consolidation load on the vertical drainage area is added to the sand consolidation load by the embankment provided on the airtight sheet. As a result, the soil is subjected to consolidation dewatering with a larger consolidation load.

In the method for improving soft ground according to claim 4, since any or all of the drain material, the water-permeable material and the airtight sheet used in each step are made of a biodegradable molding material, Is easily decomposed by microorganisms and water existing in the soil or water in the ground, and it is not necessary to remove these members.

In the improvement method for soft ground according to claim 5, the biodegradable molding material constituting the drain material, the water flow material and the airtight sheet used in each step is mainly composed of natural polymer. Even if it is decomposed in the ground after the enforcement, it will not adversely affect the environment.

The method for improving soft ground according to claim 6 is characterized in that the vacuum pump is operated intermittently. When the ground surface becomes a negative pressure state and the pressure difference causes water and air in the ground to be sucked out to the ground surface,
In the ground, especially around the drain material, the gaps between the particles forming the ground are narrowed, and it becomes difficult for water and air to pass through. As a result, the water and air remaining in the ground cannot be sufficiently sucked out due to the pressure difference.

In the improved construction method according to this claim, since the vacuum pump is operated intermittently,
On the upper surface of the ground, normal pressure and negative pressure are created alternately. When the state of negative pressure changes to the state of normal pressure, the difference in pressure causes air to be absorbed. For this reason, a large impact force is applied to the ground to cause air to vibrate and vibrate, so that the ground, particularly the particle gaps that form the ground around the drain material, expand, and water and air easily pass through.

As a result, the vacuum pump is activated again,
When the ground surface changes from a normal pressure state to a negative pressure state, the pressure difference causes water and air in the ground to be sucked out.

In the method for improving soft ground according to the seventh aspect, when the top surface of the ground changes from a negative pressure state to a normal pressure state, not only air enters due to the pressure difference, but also positively. Since air is sent to the ground, the impact force acting on the ground becomes larger, and the ground, especially the particle gaps that make up the ground around the drain material, expand further,
Water and air are easier to pass through.

As a result, the water and air in the ground can be sucked out more effectively, and the upper surface of the ground can be returned to the normal pressure state more quickly.

In the method for improving soft ground according to the eighth aspect, by vibrating the drain material, the pores of the ground, particularly the particles constituting the ground around the drain material, are widened, and water and air can easily pass through.

According to the ninth aspect of the present invention, in the apparatus for improving soft ground, the drain material is driven at a predetermined interval leaving the upper end in the ground so that the drain material comes into contact with the upper end of the drain material. A water permeable material is arranged horizontally, and a vacuum pump is connected to this water permeable material. Further, if the air-tight sheet is covered on the ground together with the drain material upper end and the water-passing material, and the vacuum pump is operated in this state, the upper surface of the ground becomes a negative pressure state, and a difference is generated between the pore water pressure in the ground. Like

Due to this pressure difference, water and air in the ground are sucked out to the ground surface through the vertical drainage wall formed in the ground, and the water and air on the ground surface come into contact with the upper end of the drain material. It is designed to be discharged through the horizontal water-passing material (to the drain tank).

In the apparatus for improving soft ground according to the tenth aspect of the present invention, water and air sucked onto the ground surface cause a gap between the net constituting the water-permeable material and the fiber sheet attached to the net surface, And is discharged through the fiber gap in the fiber sheet (to the drain tank).

In the soft ground improving construction device according to the eleventh aspect of the present invention, the water-permeable material provided integrally with the airtight sheet as the inside (ground side) is in contact with the upper end of the drain material. The installation of the airtight sheet and the placement of the water-permeable material can be done at the same time. In addition, transportation can be handled as one item.

In the apparatus for improving soft ground according to the twelfth aspect, any or all of the drain material, the water-permeable material and the airtight sheet are made of biodegradable molding material. It is easily decomposed by microorganisms and water present in the inside or water, and it is not necessary to remove these members.

In the apparatus for improving soft ground according to the thirteenth aspect, the biodegradable molding material constituting the drain material, the water-permeable material and the airtight sheet is mainly composed of natural polymer.
Even if it is decomposed in the ground after the enforcement, it will not adversely affect the environment.

In the apparatus for improving soft ground according to claim 14, when the pipeline for feeding air is provided on the upper surface of the ground, when the upper surface of the ground shifts from the negative pressure state to the normal pressure state. In addition, not only the air enters due to the pressure difference but also the air is positively sent through the pipeline, the impact force acting on the ground becomes larger, and the ground, especially the particle gap forming the ground around the drain material, becomes more It spreads widely, making it easier for water and air to pass through.

As a result, the water and air in the ground can be more effectively sucked out, and the upper surface of the ground can be returned to the normal pressure state more quickly.

In the apparatus for improving soft ground according to the fifteenth aspect, since the drain material vibrates by the vibration generator, the ground, particularly the particle gaps forming the ground around the drain material expand, and water and air Becomes easier to pass.

The method for improving soft ground and the apparatus for improving soft ground according to the present invention will be described in detail below with reference to an embodiment shown in the drawings. First, a method for improving soft ground according to claims 1 to 8 will be described. This improved method is a step of forming a vertical drainage wall in the ground, a step of disposing a water-permeable material connected to the vacuum pump, and a step of placing a consolidation load of sand on the vertical drainage wall area, It consists of a step of covering the ground with an airtight sheet and a step of operating a vacuum pump to create a negative pressure state on the top surface of the ground.

The step of constructing the vertical drainage wall in the ground consists of driving the drain material at a predetermined interval in the ground leaving the upper end portion. A conventionally used drain material can be used as the drain material. Among them, as shown in FIG. 1, the paper drain material penetrates into the ground A while being inserted in the mandrel 12, and the mandrel 12 is left with the paper drain material 11 left on the ground A.
It is preferable because it can be placed by pulling it up, it is easy to place it, does not easily cause clogging, and has a function as a reliable water-permeable material. In this embodiment, this drain material is used.

By placing the drain material 11 in the ground A at a predetermined interval, vertical drainage walls are formed in the ground A at a predetermined interval, and each drainage water is drained. Water and air contained in the ground between the walls pass through the drainage wall made of the drain material 11 as shown by the arrow in FIG.
It is sucked up to the upper surface and discharged from the drain material upper end 11a left on the ground upper surface.

Next, the water-permeable material connected to the vacuum pump is placed. As shown in FIG. 2, the drain material upper end 11 a projects from the upper surface of the ground A. Water-transmitting material 13
Are arranged in parallel so that they contact each other. Water material 1
3 may be any as long as it has a function as a passage through which water and air can move in the longitudinal direction of the water-permeable material 13, but an opening through which water and air from the ground side enter the water-permeable material. , For example, holes and slits may be blocked by sand and earth in the ground, making it difficult for water and air to enter the water-permeable material. Similarly, sand and earth in the ground may block passages. Further, it is preferable to use a structure in which water and air are less likely to move in the longitudinal direction of the water-permeable material.

Specifically, as shown in FIG. 3, a preferable example is a plastic net 14 and a fiber sheet 15 laminated on the surface thereof. In the water-permeable material 13, water and air enter from the side of the fiber sheet 15 laminated on the surface of the plastic net 14, and move through the gap between the plastic net 14 and the fiber sheet 15 and between the constituent fibers of the fiber sheet 15. Like

A vacuum pump 1 is provided at one end of the water-permeable member 13.
6 are connected. In the embodiment shown in FIG. 2, the vacuum pump 16 is not directly connected to one end of the water-permeable member 13 but via the drain tank 17. That is, the negative pressure from the vacuum pump 16 is transmitted to the water-permeable member 13 via the drain tank 17. By this action, water and air enter the water-permeable material 13, move in the water-permeable material 13, and are discharged to the drainage tank 17.

Then, as shown in FIG. 4, the ground A is covered with the airtight sheet 18 together with the drain material upper end 11a and the water-permeable material 13. The airtight sheet may be a synthetic resin sheet, a fiber substrate surface laminated with a synthetic resin film, or the like, as long as it is a material through which air cannot pass. When the ground A is covered with the airtight sheet 18 and the vacuum pump 16 is operated in this state, the negative pressure from the vacuum pump 16 is transmitted to the water passing material 13 via the drain tank 17, and the upper surface of the ground A is negative. A pressure state is reached, and a difference is generated between the pore water pressure in the ground A.

Due to this pressure difference, water and air in the ground A are sucked out to the surface of the ground A through the vertical drainage wall formed in the ground A, as indicated by the arrow in FIG.
The water and air on the ground surface are discharged to the drainage tank 17 through the water-passing member 13 arranged horizontally so as to come into contact with the drain member upper end 11a.

The vacuum pump 16 may of course be operated continuously, but it may also be operated intermittently. As shown in FIG. 5, when the ground A surface is in a negative pressure state and the pressure difference causes water and air in the ground A to be sucked out to the ground A surface, the ground, especially around the drain material 11, is The gap between the particles forming A becomes narrow, and it becomes difficult for water and air to pass through. As a result, the water and air remaining in the ground A cannot be sufficiently sucked out due to the pressure difference.

By intermittently operating the vacuum pump,
On the upper surface of the ground A, normal pressure and negative pressure are alternately created. When the state of negative pressure changes to the state of normal pressure, air will be absorbed. For this reason, air is absorbed into the ground A due to the pressure difference, and the impact force at this time acts on the ground A to rock the ground A. As a result, as shown in FIG. The gap between the particles forming the ground A around 11 is widened, and water and air can easily pass through.

Then, by operating the vacuum pump 16 again, the surface of the ground A is changed from the normal pressure state to the negative pressure state, so that the water and air in the ground A are sucked out due to the pressure difference. become. By intermittently operating the vacuum pump in this way, water and air in the ground are sucked out more efficiently.

When the vacuum pump is intermittently operated to alternately create a normal pressure state and a negative pressure state on the upper surface of the ground A, when the negative pressure state is changed to the normal pressure state, the pressure difference is caused. Not only can you like the air, but you can also send the air more positively. In this case, the impact force acting on the ground is also larger,
The ground, especially the particle gaps that make up the ground around the drainage material, become larger and water and air are more easily passed.

As a result, the water and air in the ground can be sucked out more effectively, and the upper surface of the ground can be returned to the normal pressure state more quickly.

Another method of rocking the ground A is to vibrate the drain material. Also in this case, the ground, especially the particle gaps forming the ground around the drain material, are widened, and water and air can easily pass through. If the method of vibrating the drain material and the method of intermittently operating the vacuum pump described above are used together, the water and air in the ground A can be sucked out more effectively.

As shown in FIG. 7, sand 19 is formed in the vertical drainage wall construction area formed by placing the drain material 11 in the ground A at a predetermined interval while leaving the upper end 11a.
It is also possible to overload the consolidation load due to. As a result, the consolidating and dehydrating of the ground A is performed by the consolidating load of the sand 19 placed on the vertical drainage area, and the water and air in the ground A are cooperated with the suction due to the aforementioned pressure difference. To promote the discharge to the upper surface of the ground A.

Further, as shown in FIGS. 8 and 9, embankment 20 can be provided on the airtight sheet 18. In the embodiment shown in FIG. 8, the embankment 20 is applied on the airtight sheet 18 that covers the ground A together with the drain material upper end 11a and the water-passing material 13, and the embankment 2 applied on the airtight sheet 2
With the consolidation load of 0, the soil A is compressed and dehydrated, and in cooperation with the suction due to the aforementioned pressure difference, the water and air in the soil A are expelled to the upper surface of the soil.

That is, when the embankment 20 is placed on the airtight sheet 18, since water and air are present in the ground A at the beginning of the evacuation, the consolidation load due to the embankment 20 is the deep portion (L2) of the ground A. ) Does not work, but works around the relatively shallow part (L1). Since the soft ground not only has an improved surface but also the surrounding area is soft (the strength is small), the consolidation loading by the embankment 20 acts on the surrounding area.

As the water and air in the ground A are sucked out by the subsequent vacuuming, the pressure in the ground A gradually decreases. When the pressure is reduced, the consolidation load due to the embankment 20 will work even to the deep part (L2) of the ground A, and more effective and reliable discharge of water and air, improvement to the hard ground (stable ground) Will be done.

In this case, the pore water pressure in the ground A temporarily rises due to the pressure due to the consolidation load of the embankment 20. However, since the inside of the drain material 11 in the ground A is decompressed, the water and air in the ground A are quickly sucked to the surface of the ground A, and the increase in pore water pressure is immediately canceled. .

On the other hand, FIG. 9 shows an embodiment in which the consolidation load of sand 19 is placed on the vertical drainage wall construction area and the embankment 20 is provided on the airtight sheet 18. In this case, in addition to the consolidation load of sand 19 on the ground A, the consolidation load of the embankment 20 acts, and the consolidation dehydration of the ground A is performed by the larger consolidation load.

Simultaneously with the subsequent vacuuming, water and air in the ground A are sucked out, so that the ground A is gradually decompressed. The consolidation load due to the sand 19 and the embankment 20 is the consolidation load of the sand 19. It works from the depth of only heavy (L3) to the deepest part of the ground A (L4), and more effective and reliable discharge of water and air, improvement to hard ground (stable ground) Will be done.

For example, sand 1 is added to the vertical drainage wall construction area in FIG.
When only the consolidation load of 9 is overlaid, the depth (improved depth) at which consolidation dehydration can be promoted is 10.0 t /
The limit is m ² and the depth is 10.0 m (actually 8
However, when the embankment 20 is applied to this, the depth is significantly lower than the limit of 10.0 m, which has been the limit until then, and it is possible to improve to the deepest part of the ground A.

It should be noted that any or all of the drain material, the water-permeable material and the airtight sheet used in each step may be made of a biodegradable molding material. The biodegradable molding material refers to a material that is easily decomposed by microorganisms or water present in soil or water. When the improved construction method is implemented according to the above method using the drain material, water-permeable material and airtight sheet composed of this biodegradable molding material, if the mortar is injected after the execution, the drain material, water-permeable material And since the biodegradable molding material that constitutes the airtight sheet is easily decomposed by microorganisms and water existing in the soil or water in the ground, it is not necessary to remove these members, and improvement of soft ground is possible. It is possible to significantly reduce the cost and labor required for the.

Examples of the biodegradable molding material include starches such as potatoes, rice, and corn, starch derivatives obtained by copolymerizing starch with vinyl monomers such as vinyl acetate, pulp,
Plant fiber or plant powder such as cellulose, natural rubber, plant polymers such as gum arabic, casein, gelatin,
Those mainly composed of natural polymers such as animal proteins such as gluten are preferable. The reason for this is that with those mainly composed of these natural polymers, even if they are decomposed in the ground after the execution, they will not adversely affect the environment.

Next, an apparatus for improving soft ground according to claims 9 to 15 will be described. As shown in FIG. 4, this improved construction device is provided with a drain material 11 that is placed in the ground A.
A water-permeable material 13 arranged so as to contact the drain material upper end 11a, and a vacuum pump 16 connected to the water-permeable material 13.
And an airtight sheet 18 covering the ground.

The drain material 11 has an upper end 11 in the ground A.
A vertical drainage wall can be formed in the ground by placing it at a predetermined interval while leaving a, and in this embodiment, a vertical continuous paper is passed through the strip-shaped base paper conventionally used. A card board with water holes was used. Then, the water and air contained in the ground A between the drainage walls formed by placing the drain material 11 are sucked up to the upper surface of the ground A through the drainage wall composed of the drain material 11 as shown by the arrows in the figure. The drain material is discharged from the upper end 11a of the drain material left on the upper surface of the ground.

A device for generating vibration may be attached to the drain material 11. As this vibration generating device, for example, electrodes (not shown) made of a conductive plate such as iron or aluminum are attached to the front and back in the thickness direction of the drain material 11, and a current is caused to flow through them to generate a magnetic field. The electrode sucks and repels repeatedly,
The thing which made it cause a vibration can be mentioned.

The water-passing material 13 is the upper end portion 11 of the drain material.
The drain member 11 is horizontally arranged so as to come into contact with a.
It should be a movement route for horizontally moving water and air sucked up to the upper surface of the ground A through the drainage wall made of and discharging it to the outside of the soft ground (or the outside of the improved area). As a mode of this water-permeable material 13, as shown in FIG. 3, a net 14 and a fiber sheet 1 laminated on both surfaces thereof.
5, which allows water and air to invade and move through the gap between the net 14 and the fiber sheet 15 and the gap between the fibers forming the fiber sheet (in this case, the fiber sheet is made of non-woven fabric). However, a woven fabric or a knitted fabric may be used as well), or a net in which a fiber sheet is laminated only on one side of the net may be mentioned as a preferable example.

The water-permeable material 13 is a long material having a width of, for example, 1 m to 2 m, and is wound in a roll shape during transportation or the like, and is placed on the drain material upper end 11a. The upper surface of the ground A may be entirely unrolled from one end side to the other end side of the ground A so as to cover the entire upper surface of the ground A. Further, the water-permeable material 13 is the drain material upper end 11
It has a strip shape having a width capable of covering the vicinity of a, and is arranged from one end side to the other end side along the drain material upper end 11a on the upper surface of the ground A, and the upper surface of the ground A is in a stripe shape or a grid shape. It can also be placed in.

A vacuum pump 16 is connected to the water-permeable member 13. The water-passing material 13 and the vacuum pump 16 do not necessarily have to be directly connected, and may be connected via a drain tank 17 as shown in FIG. 4, for example. Vacuum pump 1
The performance and model of No. 6 are not particularly limited, and may be anything as long as the upper surface of the ground A can be kept in a negative pressure state for a long time. Although the vacuum pump 16 is connected to only one end of the water material 13 in the drawing, it may be connected to both ends.

The airtight sheet 18 may be any material such as a synthetic resin sheet or a laminate of a synthetic resin film on the surface of a fiber base as long as it is a material that does not allow air to permeate. When the ground A is covered with the airtight sheet 18 and the vacuum pump 16 is operated in this state, the negative pressure from the vacuum pump 16 is transmitted to the water passing material 13 via the drain tank 17, and the upper surface of the ground A is negative. A pressure state is reached, and a difference is generated between the pore water pressure in the ground A.

Due to this pressure difference, water and air in the ground A are sucked out to the surface of the ground A through the vertical drainage wall formed in the ground A, as indicated by the arrow in FIG.
The water and air on the ground surface are discharged to the drainage tank 17 through the water-passing member 13 arranged horizontally so as to come into contact with the drain member upper end 11a.

The airtight sheet 18 and the water-permeable material 1
3 and 3 can be provided integrally. In this case, the water-permeable material 1 in which the airtight sheet 18 and the airtight sheet 18 are integrally provided
By setting 3 as the inner side (ground side) so as to be in contact with the drain material upper end 11a, it is possible to install the airtight sheet 18 and the water-passing material 13 at one time, and also to transport the same. It becomes possible to handle it as an article.

Any or all of the above-mentioned drain material, water-permeable material and airtight sheet may be made of biodegradable molding material. In this case, if mortar is injected after the operation, the biodegradable molding materials that make up the drain material, water flow material and airtight sheet will be easily decomposed by microorganisms and water present in the soil or water in the ground. Because it will
Since it is not necessary to remove these members, the cost and labor required for improving the soft ground can be significantly reduced.

Further, as biodegradable molding materials, starches such as potatoes, rice and corn, starchy derivatives obtained by copolymerizing starch with vinyl monomers such as vinyl acetate, plant fibers such as pulp and cellulose, or Even if it is decomposed in the ground after the execution, when the ones mainly composed of plant powders, natural polymers such as natural gums and gum arabic and natural polymers such as animal proteins such as casein, gelatin and gluten are used. It has the advantage of not adversely affecting the environment.

A pipeline for sending air to the upper surface of the ground is provided, and when the upper surface of the ground shifts from a negative pressure state to a normal pressure state, not only does air enter due to the pressure difference, but also through the pipeline. The air can be positively sent in. In this case, the impact force acting on the ground becomes larger, the particle gaps forming the ground, especially the ground around the drain material, become wider, and water and air become easier to pass through.

As a result, there are advantages that water and air in the ground can be sucked out more effectively, and the upper surface of the ground can be returned to the normal pressure state more quickly.

It should be noted that what has been shown above is merely an example of explanation, and for example, fixing means may be provided to the drain material upper end portion 11a and the water flow material 13 so that the positions thereof do not shift during construction. Etc. can be freely changed within the scope described in the claims.

[0083]

In the method for improving soft ground according to the first aspect of the present invention, the upper surface of the ground is covered with the airtight sheet together with the upper end of the drain material and the water-permeable material, and the vacuum pump connected to the water-permeable material is used. Since it is evacuated by operating it, the upper surface of the ground is in a negative pressure state, and there is a difference with the pore water pressure in the ground, and this pressure difference causes the drain material to leave a predetermined upper part in the ground. By arranging at intervals, the water and air in the ground are sucked out to the ground surface through the vertical drainage wall formed in the ground.

Therefore, in this improved construction method, a perforated tube connected horizontally to the vacuum pump is arranged at the upper end of the card board so as to come into contact with the card board, and the card board and the perforated tube are formed by a sand layer. It is possible to discharge water and air in the ground more efficiently and reliably as compared with the conventional improved construction method of covering.

Further, in this construction method, the upper surface of the ground is covered with the airtight sheet, so that the negative pressure environment can be realized more efficiently. Therefore, it is necessary to create the negative pressure environment on the upper surface of the ground. The cost can be significantly reduced.

In the method for improving soft ground according to the second aspect of the present invention, the consolidation load due to sand is placed on the vertical drainage wall construction area, and the consolidation load due to this sand causes pressure consolidation dehydration of the ground. It progresses at the same time as the suction due to the difference, and the water and air in the soft ground are efficiently discharged to the upper surface of the ground.

In the method for improving soft ground according to the third aspect, when the load for compaction of sand is not placed on the vertical drainage wall construction area, the load is applied by the embankment provided on the airtight sheet. Consolidation dehydration of the ground proceeds at the same time as suction due to the pressure difference, and water and air in the soft ground are efficiently discharged to the upper surface of the ground. That is, the consolidation load due to the embankment works even deep inside the ground, effective and reliable discharge of water and air, and improvement to hard ground (stable ground) can be achieved.

Further, when the consolidation load of sand is placed on the vertical drainage wall construction area, the stronger consolidation load of sand and embankment acts on the ground and deeply, which is more effective. Efficient and reliable discharge of water and air, and improvement to hard ground (stable ground) will be made.

In the method for improving soft ground according to claim 4, since any or all of the drain material, the water-permeable material and the airtight sheet used in each step are made of biodegradable molding material, Is easily decomposed by microorganisms and water existing in the soil or water in the ground, and it is not necessary to remove these members, and it is possible to significantly reduce the cost and labor required for improving soft ground. it can.

In the method for improving soft ground according to claim 5, the biodegradable molding material constituting the drain material, the water-permeable material and the airtight sheet used in each step is mainly composed of natural polymer. Even if it is decomposed in the ground after the enforcement, it will not adversely affect the environment.

In the method for improving soft ground according to the sixth aspect, the vacuum pump is intermittently operated to alternately create a normal pressure state and a negative pressure state on the upper surface of the ground. By sucking out the water and air of the ground, the particle gap that constitutes the ground, especially the ground around the drain material, becomes narrower,
The phenomenon that it becomes difficult for water and air to pass is unlikely to occur, and water and air in the ground can be efficiently and reliably sucked out.

In the method for improving soft ground according to claim 7, when the top surface of the ground shifts from a negative pressure state to a normal pressure state, not only is air introduced due to the pressure difference, but also positively. Since air is sent to the ground, the impact force acting on the ground becomes larger, and the ground, especially the particle gaps that make up the ground around the drain material, expand further,
Water and air are easier to pass through.

As a result, the water and air in the ground can be sucked out more effectively, and the upper surface of the ground can be returned to the normal pressure state more quickly.

In the method for improving soft ground according to the eighth aspect, by vibrating the drain material, the ground, especially the particle gaps forming the ground around the drain material, widen, and water and air easily pass through.

In the apparatus for improving soft ground according to claim 9, the upper surface of the ground is covered with an airtight sheet together with the upper end of the drain material and the water-permeable material, and a vacuum pump connected to the water-permeable material is used for vacuuming. As it is pulled, the upper surface of the ground is in a negative pressure state, and there is a difference between the pore water pressure in the ground and this pressure difference causes the drain material to leave a predetermined interval in the ground leaving the upper end. By placing
Water and air in the ground are sucked out to the ground surface through a vertical drainage wall formed in the ground.

Therefore, in this improved construction device,
It is more efficient than the conventional improved construction method in which a perforated pipe connected horizontally to the vacuum pump is placed at the upper end of the card board so as to contact it, and the card board and perforated pipe are covered with a sand layer. In addition, it is possible to reliably discharge water and air in the ground.

Further, in this improved construction device, since the upper surface of the ground is covered with the airtight sheet, the negative pressure environment can be realized more efficiently, so that the negative pressure environment is created on the upper surface of the ground. The cost required for can be reduced significantly.

In the apparatus for improving soft ground according to the tenth aspect, water and air sucked onto the ground surface cause a gap between the net constituting the water-permeable material and the fiber sheet attached to the net surface, And it is discharged through the fiber gap in the fiber sheet (to the drainage tank), so clogging is less likely to occur, and water and air are discharged to the ground surface by negative pressure, and also discharged to the ground surface. Water and air (to the drain tank) can be discharged stably and efficiently.

According to the eleventh aspect of the soft ground improvement construction device, the watertight material provided integrally with the airtight sheet is placed inside (ground side) so that the airtight sheet comes into contact with the upper end of the drain material. By installing the air-tight sheet, it is possible to install the airtight sheet and the water-permeable material at the same time, and the handling such as transportation is easy.

[0100] In the apparatus for improving soft ground according to the twelfth aspect, since any or all of the drain material, the water-permeable material and the airtight sheet are made of biodegradable molding material, the soil in the ground after the operation is carried out. It is easily decomposed by microorganisms and water present in the inside or water, and it is not necessary to remove these members, and the cost and labor required for improving the soft ground can be greatly reduced.

In the apparatus for improving soft ground according to claim 13, the biodegradable molding material constituting the drain material, the water-permeable material and the airtight sheet is mainly composed of natural polymer.
Even if it is decomposed in the ground after the enforcement, it will not adversely affect the environment.

In the apparatus for improving soft ground according to claim 14, when a pipeline for feeding air is provided on the upper surface of the ground, when the upper surface of the ground shifts from a negative pressure state to a normal pressure state. In addition, not only the air enters due to the pressure difference but also the air is positively sent through the pipeline, the impact force acting on the ground becomes larger, and the ground, especially the particle gap forming the ground around the drain material, becomes more It spreads widely, making it easier for water and air to pass through.

As a result, water and air in the ground can be sucked more effectively, and the upper surface of the ground can be returned to the normal pressure state more quickly.

In the apparatus for improving soft ground according to the fifteenth aspect, since the drain material vibrates by the vibration generator, the ground, especially the particle gaps forming the ground around the drain material expand, and water and air Becomes easier to pass.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view showing a state in which water-permeable members are arranged in parallel so as to come into contact with the upper end portion of the drain member.

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

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

FIG. 5 is a schematic diagram showing the ground around the drain material after water and air have been sucked out.

FIG. 6 is a schematic diagram showing a state in which the particle gaps forming the ground around the drain material are expanded by returning from a negative pressure state to a normal pressure state.

FIG. 7 is a cross-sectional view showing a state in which a consolidation loading load of sand is placed on a vertical drainage wall construction area.

FIG. 8 is a cross-sectional view showing a state in which the embankment is provided on the airtight sheet when the sand compaction load is not placed on the vertical drainage wall construction area.

FIG. 9 is a cross-sectional view showing a state in which embankment is provided on an airtight sheet when a compaction loading load of sand is placed on the vertical drainage wall construction area.

FIG. 10 is a cross-sectional view showing a conventional improvement construction device for soft ground.

[Explanation of symbols]

 11 ... Drain material 13 ... Water material 14 ... Net 15 ... Fiber sheet 16 ... Vacuum pump 18 ... Airtight sheet 19 ... Sand 20 ... Embankment

Claims (15)

[Claims] 1. A step of forming a vertical drainage wall in the ground by placing the drain material at a predetermined interval in the ground leaving the upper end portion, and a step of contacting with the drain material upper end portion. A step of horizontally arranging the water-passing material connected to the vacuum pump, a step of covering the ground with an airtight sheet together with the drain material upper end and the water-passing material, and operating the vacuum pump to apply a negative pressure to the top surface of the ground. An improvement method for soft ground, which is characterized by the process of creating a state. 2. The method for improving soft ground according to claim 1, wherein a consolidation load of sand is placed on the vertical drainage wall area. 3. The method for improving soft ground according to claim 1, wherein embankment is performed on the airtight sheet. 4. The drain material, the water-permeable material, and any or all of the airtight sheets used in each of the steps are made of a biodegradable molding material.
The method for improving the soft ground described. 5. The method for improving soft ground according to claim 4, wherein the biodegradable molding material is mainly composed of a natural polymer. 6. The method according to claim 1, further comprising a step of intermittently operating a vacuum pump to alternately create a normal pressure state and a negative pressure state on the ground upper surface.
Or the method for improving soft ground according to any one of 5 above. 7. The air is sent to the upper surface of the ground when the upper surface of the ground shifts from a negative pressure state to a normal pressure state. The method for improving soft ground described in crab. 8. The method for improving soft ground according to claim 1, wherein the drain material is vibrated. 9. A drain material placed at a predetermined interval in the ground leaving an upper end portion thereof, a water-passing material horizontally arranged so as to contact the upper end portion of the drain material, and a water-passing material. An improved construction apparatus for soft ground, comprising a vacuum pump connected to the material, and an airtight sheet covering the ground with the drain material upper end and the water-passing material. 10. The apparatus for improving soft ground according to claim 9, wherein the water-permeable material comprises a net and a fiber sheet attached to the surface of the net. 11. The apparatus for improving soft ground according to claim 9, wherein the water-permeable material is integrally provided inside the airtight sheet. 12. The improvement of soft ground according to claim 9, 10 or 11, wherein any or all of the drain material, the water-permeable material and the airtight sheet are made of a biodegradable molding material. Construction equipment. 13. The apparatus for improving soft ground according to claim 12, wherein the biodegradable molding material is mainly composed of a natural polymer. 14. A pipeline for feeding air to the upper surface of the ground is provided.
Or the improvement construction device for soft ground according to any one of 13 above. 15. The vibration generator is attached to the drain member.
The improvement construction device for soft ground according to any one of 2, 13, and 14.