JP2004218377A - Improvement method for soft ground - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for improving a soft ground, which can drain water stagnating on an airtight sheet and also, when an embankment is made on the soft ground, can avoid liquefaction of the embankment to be kept in a stable condition. <P>SOLUTION: A drainage structure including a water stopper valve 10 is provided on the air-tight sheet 1. Furthermore, the water on an upper surface of the airtight sheet 1 is drained to the inside of the airtight sheet 1. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for improving a soft ground, which improves a soft ground into a hard ground by discharging a large amount of water contained in the soft ground such as a landfill area around a lake. In detail, an apparatus for improving soft ground capable of draining water accumulated on an airtight sheet and preventing liquefaction of the embankment and maintaining a stable state even when embankment is performed on the improved ground About.
[0002]
[Prior art]
Conventionally, as an apparatus for improving soft ground, for example, there is an apparatus shown in FIGS. The improvement device for soft ground shown in FIGS. 4 and 5 is a vertical drain material for forming a vertical drain wall in the ground A by driving the improved ground A while leaving the upper end portion 11a at a predetermined interval. 31, a horizontal drain material 33 disposed in parallel so as to contact the upper end portion 13a of the vertical drain material 31 protruding from the upper surface of the ground A, and a vacuum tank connected to one end of the horizontal drain material 33 A water collecting pipe 35 connected to a vacuum pump 36 via 37 and an airtight sheet 38 covering the improved ground A together with the upper end 31a of the vertical drain material 31, the horizontal drain material 33 and the water collecting pipe 35 are provided.
[0003]
In the improved apparatus 30, the negative pressure from the vacuum pump 36 is transmitted to the horizontal drain material 33 via the vacuum tank 37 and the water collecting pipe 35, and further into the improved ground A through the vertical drain material 31 with which the upper end 31a contacts. Thus, the ground A around the vertical drain member 31 is in a negative pressure state, and a difference is generated between the ground A and the pore water pressure in the ground A.
[0004]
Then, due to this pressure difference, water and air in the ground A are sucked out to the surface of the ground A through a vertical drain wall made of the vertical drain material 31 formed in the ground A. Water and air on the ground surface are discharged to a vacuum tank 37 through a horizontal drain material 33 and a water collecting pipe 35 which are arranged horizontally so as to come into contact with the upper end 31a of the vertical drain material 31. I have.
[0005]
As shown in FIG. 4, the improved ground A consolidates and sinks as much as the water and the air are sucked out, and a concave portion 30 is created there. Thereafter, as shown in FIG. 5, the earth and sand 42 are scattered in the recess 30 formed by the consolidation settlement of the improved ground A. As a result, a consolidation load is applied on the improved ground A by the embankment made of the earth and sand 42, and consolidation dewatering of the improved ground A is performed (for example, see Patent Document 1).
[0006]
[Patent Document 1]
JP-A-11-131465 (pages 2 to 9, FIGS. 7 and 8)
[0007]
[Problems to be solved by the invention]
However, rainwater, snow-melting water, or inflow water from the surroundings accumulates in the concave portion 30 formed by the consolidation settlement of the improved ground A improved by the above-described improvement device, and the condensed water enters the concave portion 30 by the retained water. The embankment 43 made of the scattered earth and sand was liquefied, and the embankment 43 was unstable.
[0008]
The present invention has been made in view of such circumstances, and is capable of draining water accumulated on an airtight sheet, preventing liquefaction of the embankment even when embankment is performed on the improved ground, and stabilizing the embankment. It is an object of the present invention to provide a soft ground improvement device capable of maintaining a stable state.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is characterized in that each vertical drain material is provided at a predetermined interval in the improved ground under a hermetic sheet covering the upper surface of the improved ground, and each vertical drain material is provided. And a drainage path for draining pore water sucked out of the improved ground due to the propagation of the vacuum pressure. In a soft ground improvement device having a soft ground improvement device, characterized in that a drainage structure is provided in the airtight sheet, and water on the upper surface of the airtight sheet is drained into the airtight sheet. did.
[0010]
According to a second aspect of the present invention, the drainage structure is a water stop valve provided on an airtight sheet, and water on the upper surface of the airtight sheet flows into the airtight sheet through the water stop valve, and is improved through a drainage path below the airtight sheet. The gist of the invention is an apparatus for improving soft ground according to claim 1, wherein the apparatus is drained out of the ground.
[0011]
According to a third aspect of the present invention, the water stop valve is connected to a drain tank connected to a horizontal drain material and a water collection pipe, and water on the upper surface of the airtight sheet flows into the drain tank through the water stop valve, and the drain tank is The apparatus for improving soft ground according to claim 2 is characterized in that the apparatus is drained out of the improved ground through a drain pipe connected to the ground.
[0012]
The gist of the invention according to claim 4 is that the improvement device for soft ground according to claims 1 to 3, wherein the second horizontal drain material and the water collecting pipe are arranged on the upper surface of the airtight sheet.
[0013]
The invention according to claim 5, wherein the drainage structure is a drainage slit including an unbonded portion formed at a joint portion of the airtight sheet, and water on the upper surface of the airtight sheet flows into the airtight sheet through the drainage slit, The gist of the invention is a soft ground improvement apparatus according to claim 1, wherein the water is drained out of the improved ground through a drainage path below the airtight sheet.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an apparatus for improving soft ground of the present invention (hereinafter, referred to as an improvement apparatus) will be described in more detail with reference to an embodiment shown in the drawings. The improvement device shown in FIG. 1 transmits a vacuum pressure into the improved ground A to create a decompression region isolated from the improved ground peripheral portion B in the improved ground A. It has a propagation path for the vacuum pressure for transmitting the pressure to the improved ground A, and another drainage path.
[0015]
In the improvement device shown in FIG. 1, vertical drain members 6 are cast in the improved ground A at predetermined intervals. A number of horizontal drain members 2 are connected to each of the vertical drain members 6. Furthermore, each horizontal drain material 2 is connected to water collecting pipes 3 and 4, and is connected to a vacuum pump 11 via a ventilation pipe 13 and a vacuum tank 7 connected to the water collecting pipes 3 and 4.
[0016]
Then, the negative pressure from the vacuum pump 11 is transmitted to the horizontal drain material 2 via the vacuum tank 7, the ventilation pipe 13, and the water collecting pipe 3, and further through the vertical drain material 6, which is in contact with the upper end portion, in the improved ground A. The ground A around the vertical drain member 6 is in a negative pressure state, and a difference is generated between the ground A and the pore water pressure in the ground A.
[0017]
Due to this pressure difference, water and air in the improved ground A are sucked out through the vertical drainage wall made of the vertical drain material 6 formed in the improved ground A, and collected through the horizontal drain material 2 and the water collection pipes 3 and 4. The exhausted air is exhausted to the vacuum tank 7 through the ventilation pipe 13.
[0018]
The vacuum tank 7, the ventilation pipe 13, the water collecting pipe 3, the horizontal drain material 2, and the vertical drain material 6 constitute a propagation path of the vacuum pressure for transmitting the vacuum pressure from the vacuum pump 11 to the improved ground A.
[0019]
The upper surface of the improved ground A is covered with the airtight sheet 1 together with a part of the ventilation pipe 13, the water collecting pipes 3 and 4, the upper end of the horizontal drain material 2 and the upper end of the vertical drain material 6, and a negative pressure from the vacuum pump 11. Is efficiently and reliably applied to the ground A.
[0020]
On the other hand, the water sucked through the vertical drain material 6 and collected through the horizontal drain material 2 and the water collecting pipes 3 and 4 is drained to a drain tank 5 arranged below the water collecting pipes 3 and 4 and connected to the drain tank 5. The water is drained to the vacuum tank 7 through the drain pipe 8.
[0021]
In the example shown in the drawing, a drain pump (not shown) is provided in the drain tank 5 so that the water in the drain tank 5 is forcibly drained. The water collecting pipe 4, the drain tank 5, and the drain pipe are drain paths for draining pore water from inside the improved ground A.
[0022]
The air and pore water in the improved ground A are discharged by the above-described improved device, and the improved ground A consolidates and sinks as much as the water and the air are sucked out, and the concave portion 14 is created therein.
[0023]
In the example of FIG. 1, earth and sand are scattered into the concave portion 14 formed by the consolidation settlement of the improved ground A, and the embankment 20 made of the sand is formed on the airtight sheet 1 on the improved ground A. Then, a consolidation load is applied to the improved ground A by the embankment 20, and consolidation dewatering of the improved ground A is performed.
[0024]
The airtight sheet 1 shown in FIG. 1 is provided with a drainage structure which is the greatest feature of the present invention, and rainwater, snowmelt water, or water on the upper surface of the airtight sheet 1 of the concave portion 14 formed by consolidation settlement of the improved ground A. When the inflowing water from the surroundings stagnates, the water is drained into the airtight sheet 1.
[0025]
In the case of the airtight sheet 1 shown in FIG. 1, a large number of horizontal drain materials 12 and a water collecting pipe 9 composed of a perforated pipe are arranged on the airtight sheet 1, and water that has accumulated on the upper surface of the airtight sheet 1 in the concave portion 14 is removed. It is being collected. At substantially the center of the airtight sheet 1, a water stop valve 10 is provided which communicates with the inside and outside of the airtight sheet 1, and water collected by the horizontal drain material 12 and the water collecting pipe 9 is used as a water stop valve of the airtight sheet 1. The air flows into the airtight sheet 1 (inside the yard) through 10.
[0026]
The water shutoff valve 14 in FIG. 1 can be opened and closed by a remote control, and can be opened and closed appropriately according to the amount of rainwater or snowmelt water remaining on the upper surface of the airtight sheet 1 in the concave portion 14 or the amount of water flowing from the periphery. It has become.
[0027]
Further, the water stop valve 14 shown in FIG. 1 is directly connected to the drainage tank 5, and water flowing from the upper surface of the airtight sheet 1 through the water stop valve 14 flows into the drainage tank 5, and enters the drainage tank 5. Water is drained out of the improved ground (vacuum tank 7) through the connected drain pipe 8.
[0028]
For this reason, rainwater, snowmelt water, or inflow water from the surroundings does not accumulate on the upper surface of the airtight sheet 1 of the concave portion 14 created by the consolidation settlement of the improved ground A, and the embankment 20 is not liquefied, and 20 can be maintained in a stable state.
[0029]
The configuration shown in FIG. 2 shows a configuration in which a water stop valve 10 that communicates with the inside and outside of the hermetic sheet 1 is attached to almost the center of the hermetic sheet 1 in a concave portion 14 formed by consolidation settlement of the improved ground A, In this case, the water flowing into the airtight sheet 1 from the upper surface of the airtight sheet 1 through the water stop valve 14 passes through the upper layer of the ground A, and the above-described drainage path under the airtight sheet 1, that is, the horizontal drain material 2 and the water collecting pipe 3 , 4 to a drain tank 5, and drain to the outside of the improved ground (vacuum tank 7) through a drain pipe 8 connected to the drain tank 5.
[0030]
The form shown in FIG. 3 is a drainage slit 30 formed of a non-adhered portion formed at a seam portion 1a (adhered portion) of the seam of the airtight sheet 1, and the water on the upper surface of the airtight sheet 1 passes through the drainage slit 30. The water flows into the airtight sheet 1, reaches the drainage tank 5 via the above-mentioned drainage path under the airtight sheet 1, that is, the horizontal drain material 2 and the water collecting pipes 3 and 4, and is connected to the drainage pipe 8. Through the improvement ground (vacuum tank 7).
[0031]
Note that the example shown in the above-described embodiment is merely an illustrative example. For example, water stop valves are installed at a plurality of locations on the airtight sheet according to the scale of the yard, and the water on the upper surface of the airtight sheet is more increased from the plurality of locations. It can be freely changed within the range described in the claims section, for example, to efficiently drain water into the airtight sheet.
[0032]
【The invention's effect】
In the improved device of the present invention, a drainage structure is provided on the airtight sheet, and water on the upper surface of the airtight sheet is drained into the airtight sheet. Even when the embankment is laid on the improved ground, liquefaction of the embankment can be prevented and the embankment can be maintained in a stable state.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an improved device of the present invention.
FIG. 2 is an enlarged schematic view showing a drainage structure provided on an airtight sheet in the improved device of the present invention.
FIG. 3 is an enlarged schematic view showing another drainage structure provided on the airtight sheet in the improved device of the present invention.
FIG. 4 is a schematic view showing a state in which the improved ground has been compacted and settled by the conventional improvement device.
FIG. 5 is a schematic diagram showing a state in which embankment is filled in a concave portion of the improved ground which has been compacted and settled by the improvement device shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Airtight sheet 2 ... Horizontal drain material 3, 4 ... Water collecting pipe 5 ... Drain tank 6 ... Vertical drain material 7 ... Vacuum tank 8 ... Drain pipe 11 ... Vacuum pump 20 ... embankment 10 ... water stop valve

Claims (5)

Under the airtight sheet covering the upper surface of the soft ground to be improved (hereinafter referred to as improved ground), each vertical drain material installed at a predetermined interval in the improved ground, and a horizontal drain material connected to each vertical drain material A soft ground having a propagation path of vacuum pressure composed of a water collecting pipe connected to the horizontal drain material, and a drainage path for draining pore water sucked out of the improved ground due to the propagation of the vacuum pressure. A device for improving soft ground, wherein a drainage structure is provided in the airtight sheet, and water on the upper surface of the airtight sheet is drained into the airtight sheet. The drainage structure is a water stop valve provided on the airtight sheet, so that water on the upper surface of the airtight sheet flows into the airtight sheet through the water stop valve, and is drained outside the improved ground through a drainage path below the airtight sheet. The apparatus for improving soft ground according to claim 1, wherein: The water stop valve is connected to a drain tank connected to a horizontal drain material and a water collection pipe, and water on the upper surface of the airtight sheet flows into the drain tank through the water stop valve, and is improved through a drain pipe connected to the drain tank. 3. The improvement device for soft ground according to claim 2, wherein the water is drained out of the ground. The improvement device for soft ground according to any one of claims 1 to 3, wherein a second horizontal drain material and a water collecting pipe are arranged on an upper surface of the airtight sheet. The drainage structure is a drainage slit formed of an unbonded portion formed at a joint portion of the airtight sheet, and water on the upper surface of the airtight sheet flows into the airtight sheet through the drainage slit, and is improved through a drainage path below the airtight sheet. The apparatus for improving soft ground according to claim 1, wherein the apparatus is drained out of the ground.

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