JP3589050B2 - How to improve soft ground - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for improving soft ground using, for example, a vertical drain material.
[0002]
[Prior art]
One of the methods for improving soft ground is an atmospheric pressure method using a drain material. In the atmospheric pressure method, a large number of drain materials made of PVC, plastic or non-woven fabric, etc., which have formed many pores in the vertical direction, penetrate vertically into the ground at predetermined intervals, and the capillarity causes moisture in the ground to reach the surface. It pumps water to consolidate the ground.
[0003]
FIG. 3 shows an example of equipment arrangement by the atmospheric pressure method, in which a large number of horizontal drain materials 2 intersect with a plurality of vertical drain materials 1 penetrating at predetermined intervals into the ground E of the ground improvement area. Is laid on the ground surface, and a perforated pipe 3 is piped at the end of the horizontal drain material 2 so as to intersect it. Shield the entire area. The end of the porous tube 3 is connected to one end of a suction hose 5, and the other end of the suction hose 5 is connected to a vacuum suction pump 6 arranged outside the improvement area. By burying the suction hose 5 in the ground E together with the end of the sheet 4 and fixing it, the peripheral portion of the sheet 4 is hermetically sealed.
[0004]
After the above preparatory work, the vacuum suction pump 6 is operated to generate a negative pressure between the ground surface and the sheet 4, to suck the moisture in the ground with the atmospheric pressure as a load, and to form the porous pipe 3 and the suction pipe. Water is drained out of the improvement work area through the hose 5 to promote consolidation settlement and improve the density and strength of the ground.
[0005]
[Problems to be solved by the invention]
However, in such a conventional method for improving soft ground, since the non-breathable sheet 4 is laid after the work of laying the horizontal drain material is completed, the horizontal drain material 2 may be erroneously stepped on or used as a foothold. When the work is performed, the weight of the horizontal drain material 2 sinks into the ground or is crushed to cause clogging, so that there is a problem that the water absorbing capacity is reduced. In addition, when the non-breathable sheet 4 is laid, the arrangement is disturbed by the unfolding operation of the sheet 4 and the arrangement is disturbed, and the sheet 4 may be bent or twisted.
[0006]
The present invention solves the above problems, and provides an improved method of soft ground that does not cause a decrease in absorption capacity due to stepping pressure and that can speed up preparation work for construction.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a number of vertical drain materials penetrating into the ground of the improvement area, laying on the ground surface of the improvement area, and embedding the periphery to the side of the improvement area. And a non-breathable sheet material for sealing the surface of the improved area, and a perforated pipe laid on the ground surface and buried in a horizontal drainage material , wherein the soft ground sucks the perforated pipe by a vacuum suction pump. Wherein the horizontal drainage material is laminated on the back surface of the non-permeable sheet material using a laminated sheet.
In the present invention, it is preferable that after the vertical drain material is laid, the porous tube is laid, and then the laminate sheet is laid over the entire area of the improvement area.
[0008]
Therefore, according to the present invention, since the suction removal operation can be prepared only by laying the non-breathable laminate sheet, the laying operation is simplified, and a decrease in the water absorbing ability due to the stepping pressure can be prevented.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same parts as those in the related art are denoted by the same reference numerals, and only different parts or newly added parts will be described using different reference numerals.
[0010]
FIG. 1 shows an example of the overall configuration of a facility arrangement according to the present invention, and FIG. 2 is a cross-sectional perspective view showing an enlarged main part thereof.
[0011]
In the figure, a large number of vertical drain materials 1 penetrate at predetermined intervals into the ground E in the ground improvement area, and after this penetrating operation, a perforated pipe 3 is piped to the surface of the ground. Although only one perforated tube 3 is shown in the figure, it goes without saying that a plurality of perforated tubes 3 are actually arranged.
[0012]
Thereafter, the laminate sheet 10 according to the present invention is laid over the entire area of the improvement area. As shown in an enlarged view in FIG. 2, the laminate sheet 10 is formed by laminating a horizontal drainage material 14 having a predetermined thickness on the entire surface (or a part thereof) on the back surface of a non-permeable sheet material 12. The material of the non-breathable sheet material 12 includes a PVC sheet, a rubber sheet, and the like used for a water-blocking sheet and the like. In addition, the material used for the horizontal drainage member 14 is made of an open-cell porous material that is self-supporting and does not cause early clogging.
[0013]
The non-breathable sheet material 12 and the horizontal drainage material 14 are previously laminated integrally in a factory or the like, and are conveyed to the site in a state of being wound in a roll. However, the edge of the sheet 10 is composed of the non-breathable sheet material 12 alone for a predetermined embedding margin 12a, and this embedding margin 12a is embedded in the side of the improvement area. Accordingly, the work of laying the laminate sheet 10 can be laid all over the surface by simply extending the laminate sheet 10 in the longitudinal direction from the buried margin 12a toward the improvement area.
[0014]
The sheets 10 adjacent to each other in the width direction are subjected to the same stretching operation, and then their joint edges are sealed by welding or the like, so that the airtightness of the joint edges in the width direction is also ensured.
[0015]
At this time, the worker rides on the laminate sheet 10, but the elasticity of the horizontal drainage material 14 causes the elasticity to return immediately even when the stepping pressure is applied. No, and even if it sinks into the soil, it is partial and does not interfere with the overall ventilation.
[0016]
Finally, the end of the perforated pipe 3 is connected to the suction hose 5, the side of the improvement area is excavated as shown by the broken line, and the suction hose 5 and the burial 12a of the sheet material 12 are both U-shaped in the groove. The sheet 10 is hermetically sealed by embedding in the sheet 10 and backfilling with excavated earth and sand. Then, if the other end of the hose 5 is connected to the vacuum suction pump 6 via a steam separator (not shown) or the like, the preparation of drainage is completed.
[0017]
Thereafter, by driving the vacuum suction pump 6, a negative pressure is generated between the ground surface and the laminate sheet 10, and groundwater is pumped up through the vertical drain material 1 and absorbed by the horizontal drainage material 14. The water in the ground is sucked into the pump 6 through the suction hose 5 and discharged out of the improvement work area.
[0018]
In the drawing, only one vacuum suction pump 6 is used. However, if the improvement area is a wide area, a plurality of vacuum suction pumps 6 should be provided in accordance with the capacity of the improvement area, and sufficient sealing treatment of the joint end between the sheets 4 should be performed. Thus, even if the improvement area is a wide area, it is of course possible to perform good drainage.
[0019]
【The invention's effect】
As is apparent from the above description, the method for improving soft ground according to the present invention is suitable for improving the working efficiency without reducing the water absorbing ability due to the stepping pressure as compared with the conventional method. In addition, since the work only needs to be performed to spread the sheet, the work preparation work can be speeded up.
[Brief description of the drawings]
FIG. 1 is an explanatory cross-sectional view showing an example of the overall configuration of a facility arrangement according to the method of the present invention.
FIG. 2 is an enlarged cross-sectional perspective view of a main part in a portion viewed from an arrow in FIG. 1A.
FIG. 3 is an explanatory cross-sectional view showing a configuration example of a facility arrangement in a conventional ground improvement method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vertical drain material 5 Suction hose 6 Vacuum suction pump 10 Laminate sheet 12 Non-breathable sheet material 12a Embedded space 14 Horizontal drainage material

Claims (2)

A number of vertical drains penetrating into the ground of the improvement area, and non-ventilating laid on the surface of the improvement area and having a peripheral edge embedded in the side of the improvement area to seal the surface of the improvement area A method for improving soft ground, comprising a porous sheet material and a perforated pipe laid on the ground surface and embedded in a horizontal drainage material , wherein the perforated pipe is suctioned by a vacuum suction pump,
A method for improving soft ground, characterized by laying using a laminate sheet obtained by laminating the horizontal drainage material on the back surface of the non-permeable sheet material . The method for improving soft ground according to claim 1, wherein after laying the vertical drain material, the perforated pipe is laid, and thereafter, the laminate sheet is laid over the entire area of the improvement area.

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