JP2004044224A - Driving method for multipurpose drain - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form an anti-clogging multipurpose drain by which anti-liquefaction measure and consolidation acceleration of a soft viscous ground can be realized only by one drain. <P>SOLUTION: A filter 3a using a knit fabric having a water permeability several times as much as sand or a woven fabric and a filter 3b using a continuous fiber nonwoven fabric made of a synthetic resin are laid at the surrounding of synthetic resin made cylindrical draining member in which cylindrical draining materials 2 that linear synthetic resin are overlapped in accordance with the variation of the earth layers of an objective ground or a number of holes are formed and by connecting them at an arbitrary length, one drain member 1 is formed. And an anti-liquefaction measure that the drain member 1 is placed in the ground and consolidation acceleration of a soft viscous ground are carried out. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multipurpose drain placing method capable of both countermeasures against liquefaction and promotion of consolidation of soft viscous ground.
[0002]
[Prior art]
As a liquefaction countermeasure method, a drain pipe method, a crushed stone drain method, and the like are known. The drain pipe method is a method to prevent liquefaction in sandy ground, etc., by suppressing a liquefaction phenomenon by digging a kind of well in the sandy ground and letting the groundwater pressure that rises at the time of the earthquake to the ground surface. Conventionally, for example, sand having a thin sheet-like filter material made of woven cloth wound around the outer peripheral surface of a drain pipe having a large number of holes in a plastic pipe having a diameter of 10 cm, for example. A plurality of pieces are buried in the vertical direction at a predetermined interval in the ground.
[0003]
In the crushed stone drain method, for example, a plurality of holes having a diameter of about 50 cm and a depth of about 20 m are excavated in a target sandy ground at a predetermined interval, and crushed stones are charged into the holes and filled to form crushed stone piles.
[0004]
Both the drain pipe method and the crushed stone drain method are applied only to the liquefaction countermeasures of the liquefied ground. In the case of the drain pipe method, one type of filter material made of woven fabric is wound around the pipe in order to prevent the inflow of sand. In the case of the crushed stone drain method, the particle size of crushed stone is used so that sand does not flow into it. However, both soils pass through filters and crushed stones and cause clogging of drainage for viscous ground where consolidation is a problem.
[0005]
Vertical consolidation methods such as sand drain, paper drain, and plastic board drain are known as methods for promoting consolidation of soft and viscous land. The vertical drain method is a method that installs a lot of permeable vertical drainage material in soft and viscous ground, shortens the drainage distance, promotes consolidation, and increases the shear strength of the ground. The construction method uses granular sand as a drain material, the paper drain method uses cardboard as a water-permeable material and is installed in viscous soil, and the plastic board drain method uses a plate-shaped synthetic resin water-permeable material. Is. Both methods are intended for viscous ground, and the drainage is not so permeable, so it is difficult to use it for the purpose of liquefaction countermeasures.
[0006]
In natural grounds, there are some conditions in which loose sandy soil layers and soft viscous soil layers are alternately stacked, and both sand ground liquefaction measures and cohesive soil consolidation promotion measures are required. However, since all of the drain methods use a single material filter, methods corresponding to the respective purposes have been used in combination.
[0007]
For such an alternate layered soil, a sand drain (sand pile) is created in the cohesive soil layer to promote consolidation, and in the sandy soil layer, there is a method called a composite drain method that creates a crushed stone drain by switching to crushed stone. There is a problem that sand enters the crushed stone part and water permeability is lowered.
[0008]
In order to eliminate the disadvantages of the drain pipe construction method and the crushed stone drain construction method, Japanese Patent No. 2556801 discloses that a well hole having a predetermined size and a predetermined depth is drilled at predetermined intervals in the geology and ground of sand. The resin strings are irregularly curled in these well holes and laminated in a hollow cylindrical shape having predetermined holes along the length in the center, and the contact portions between the strings are welded, and a filter is provided on the outer peripheral surface. A method for preventing sand geology and ground liquefaction has been proposed, characterized in that drainage materials arranged by wrapping materials are buried.
[0009]
According to the liquefaction prevention method of Japanese Patent No. 2556801, drainage material having a porosity of 80% or more is used in the well hole, so that any part of the filter material wound around the outer peripheral surface can be introduced into the drainage material. Since the groundwater invades, the clogging phenomenon of the filter material is hardly seen, sufficient drainage capacity can be maintained for a long time, and the drainage material itself has excellent pressure resistance, so the shape of the well hole over the long term It can be maintained.
[0010]
[Problems to be solved by the invention]
However, even the liquefaction prevention method of the above-mentioned Japanese Patent No. 2556801 uses a filter as a single material, so it can not cope with both liquefaction measures for sand ground and consolidation promotion measures for viscous ground. There wasn't.
[0011]
The object of the present invention is to eliminate the disadvantages of the conventional example, and to cope with various grounds where loose sandy soil layers and soft viscous soil layers are alternately stacked, It is an object of the present invention to provide a multipurpose drain placing method capable of promoting consolidation of a single drain and forming a drain with less clogging.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention firstly covers a filter using a knitted or woven fabric having water permeability several times that of sand and a filter using a continuous long-fiber nonwoven fabric made of synthetic resin. Attached around a cylindrical drainage material with linear synthetic resin piled up or a synthetic resin cylindrical drainage material with a large number of holes according to changes in the soil layer of the ground, and connected with any length Thus, the gist is to form as one drain material, and to prevent the liquefaction by building this drain material on the ground and to promote the consolidation of the soft viscous ground.
[0013]
Second, a filter using a knitted or woven fabric having water permeability several times that of sand is a mesh or mesh fabric knitted with yarn made of synthetic resin such as nylon, and is made of synthetic resin. A filter using a continuous long-fiber nonwoven fabric made from a raw material is a continuous long-fiber nonwoven fabric made from a polypropylene resin or a polyester resin having a water permeability of about 5 × 10 ⁻¹ to 1 × 10 ⁻³ cm / sec. It is what.
[0014]
Third, during casing drilling or penetration with construction machinery, measure the drilling speed or penetration resistance of construction machinery and determine the soil thickness on site to cope with changes in soil thickness. The gist is to determine and adjust the length of the drain material fitted with each filter on site.
[0015]
According to the first and second aspects of the present invention, in the drain material portion of the drainage material to which a filter using a knitted or woven fabric having water permeability several times that of sand is attached, the drain material is surrounded by the drain material portion. When the groundwater pressure rapidly increases, groundwater is quickly drained or ejected from the hole in the center of the drain material, so that no liquefaction phenomenon occurs in the surrounding ground. In particular, the filter has water permeability several times that of sand, does not clog, and can quickly pass excess pore water into the drain material.
[0016]
In addition, in a filter using a continuous long-fiber nonwoven fabric made of synthetic resin, in order to prevent clogging of the drain material due to the relatively slow inflow of pore water into the drain and the inflow of fine particles, Since the grain does not pass through, consolidation can be promoted for the viscous soil layer.
[0017]
Thus, by selecting the filter material, it can be used as a drain material for liquefaction countermeasures or as a consolidation promotion for soft ground. Furthermore, even with a single drilling hole, a multipurpose drain adapted to the location can be installed by connecting and installing a short drain material having an arbitrary length and filter according to the ground conditions. Furthermore, by appropriately selecting a filter, a drain that does not clog the soil at each point can be formed.
[0018]
According to the third aspect of the present invention, in addition to the above-described function, a suitable filter material that guides water to the drainage material is provided as a countermeasure against liquefaction and as a consolidation of soft and viscous land.
[0019]
According to the present invention as set forth in claim 4, in addition to the above-mentioned function, the number of preliminary geological survey points is limited, and the thickness and depth of the strata at the time of drilling are different from those estimated from the preliminary survey depending on the location. It is possible to determine and adjust the length of each drain member in response to changes in the soil layer thickness by simply determining the soil layer thickness on the spot. Become.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal side view showing an embodiment of the multipurpose drain placing method of the present invention, and FIGS. 2 and 3 are perspective views of a drain material used in the present method.
[0021]
The drain material 1 will be described first. The drainage material 2 includes a cylindrical drainage material 2 and filters 3a and 3b wound around the drainage material 2.
[0022]
The drainage material 2 is, for example, a resin string, that is, a synthetic resin of a thermoplastic material such as polypropylene, polystyrene, polyethylene, or polyester, heated and melted to form a string with a constant diameter of about 1 to 6 mm (standard diameter 2 mm) from the nozzle. Extruded and irregularly curled in order, the resin strings are laminated one after the other, and the cross-contact part of laminated string-like polypropylene or polystyrene or polyethylene or polyester having a predetermined cavity along the length in the center is welded and hollow cylinder A product similar in shape to a commercially available product (trade name: Hetimaron-Shinko Nylon Co., Ltd.) having an outer diameter of 50 mm to 150 mm is used.
[0023]
The drainage material 2 has a predetermined hole 4 formed along the length direction at the center thereof, is substantially flexible and has high pressure resistance, and has a surface opening ratio of 90 to 95% (varies depending on density). The porosity is 85 ± 5% (the density and the like can be adjusted).
[0024]
Although the basic length of the drainage material 2 is about 3 to 4 m, it can be changed to an arbitrary length by cutting it appropriately as described later, and it is extended using a dedicated joint 5 to be in the ground at a predetermined depth. Can be installed.
[0025]
Although not shown, the drainage material 2 may be a synthetic resin drainage material formed into a cylindrical shape having a large number of holes.
[0026]
The filter 3a is for liquefaction countermeasures, and uses a mesh-like or mesh-like knitted or woven fabric having water permeability several times that of sand. For example, a knitted fabric or a woven fabric made of synthetic fiber as a raw material, for example, a nylon special yarn (30 denier monofilament yarn) knitted with a basis weight of 40 g / m ² is often available and is generally commercially available (trade name: TN30-Shinko Nylon). Corporation). As shown in FIG. 4, the filter has a chain structure in the vertical direction and a triangular two-stage network structure in the horizontal direction.
[0027]
The filter 3b is for promoting consolidation of soft ground. The inflow of pore water into the drain is relatively slow, and the drain material is not clogged by the inflow of fine particles. A non-woven fabric that does not pass through is used for the filter. For example, a continuous long-fiber non-woven fabric made of polypropylene resin or polyester resin having a water permeability coefficient of about 5 × 10 ⁻¹ to 1 × 10 ⁻³ cm / sec is preferable. For example, trade name [Tafnel EX] (Mitsui Chemicals, Inc.) ) Is preferred.
[0028]
The product name [Toughnel EX] is made from polypropylene resin, and the spunbond method (polypropylene resin fed into the hopper passes through the extruder and is spun in a molten state from the spinning nozzle, thus forming a fiber-like polypropylene resin. , A continuous long fiber nonwoven fabric produced by a matte product in which fibers are entangled with each other by a needle punching machine after being taken up by a take-up device and deposited on a screen belt.
[0029]
These filters 3a and 3b are mounted by being wound around and adhered to the drainage material 2.
[0030]
As shown in FIG. 6, the drain material 1 is first drilled by the casing 8 of the tip closing bit 7 using a construction machine 6 such as a dedicated small boring machine. As shown in FIG. 5, the construction machine 6 is provided with a relatively short leader 13 on a heavy machine 12 such as a small crawler so that it can be raised and lowered, and moves the chuck / rotation drive device 14 of the casing 8 along the leader 13. In order to measure the drilling speed or penetration resistance force of the construction machine 6 when drilling or penetrating the casing 8, a displacement meter 15 is provided for the reader 13, and a rotational torque meter 16 is provided for the chuck / rotation drive device 14. The output is provided to the data recorder 17.
[0031]
In this way, as a stratum judgment system, the drilling speed or penetration resistance force of the construction machine 6 is measured to systematically grasp the soil layer state, and each soil layer of sandy soil layer α and viscous soil layer β Thickness can be determined.
[0032]
As the formation determination system, in addition to measuring the drilling speed and rotational torque of the construction machine, a density meter 21 for measuring the drilling water is provided, and the particle size of the soil particles contained in the drilling water or the drilling water You may make it discriminate | determine between sandy soil and viscous soil by the density of slime.
[0033]
Then, the drain material 1 is inserted into the built-in casing 8, and the drain material 1 is inserted with the drainage material 2 of about 3 to 4 m being sequentially added by the joint 5. At this time, the filter 3a or the filter 3b is attached to the outer periphery of the drainage material 2, and the filter 3a or the filter 3b is attached in accordance with the change in the thickness of each of the sandy soil layer α and the viscous soil layer β. Install and determine the length of the drainage material 2 locally.
[0034]
When the above-mentioned formation determination system reveals the difference in thickness or depth of each layer (sandy soil layer α, cohesive soil layer β) in the field, various filters can be used using a field cutter and a fixing jig. The drainage material 2 with the (filter 3a or filter 3b) attached thereto can be cut to an appropriate length on site.
[0035]
FIG. 7 and FIG. 8 show such a state, and the drain material 1 can be cut using a small high-speed cutting machine 18, but the drain material 1 delivered as described above includes Since the filter 3a or the filter 3b is mounted, if the filter is cut as it is, the filter is pulled and broken or twisted.
[0036]
Therefore, when cutting, as shown in FIG. 7, the filter can be cut without damaging the filter by covering the drain cutting portion with a soft plastic pipe 19 or winding the tape around the drain cutting portion.
[0037]
Further, when the drain fixing jig 20 is installed on the base of the cutting machine 18, it is possible to easily cut without mounting the pipe 19 and the tape each time. As the drain fixing jig 20, for example, a machined neck-shaped gold band can be used.
[0038]
Changes in the soil layer of the target ground are a filter 3a using a knitted or woven fabric having water permeability several times that of sand and a filter 3b using a continuous long-fiber non-woven fabric made of synthetic resin. Depending on the type, it can be installed around a cylindrical drainage material 2 with a linear synthetic resin or a synthetic resin cylindrical drainage material with a large number of holes, and connected by any length. If the drain material 1 formed as follows is inserted, the casing 8 is pulled out leaving the tip closing bit 7 as a weight, and the drain material 1 is left on the ground. Then, a drainage treatment facility (such as a gravel mat 9 or a water permeable mat) is applied to the surface layer.
[0039]
Note that a blind pipe may be connected to the drain material 1 in a place where the drain function is not required (the formation).
[0040]
【The invention's effect】
As described above, the multipurpose drain placing method of the present invention is suitable for various liquefaction countermeasures and soft-viscous land corresponding to various soils in which loose sandy soil layers and soft viscous soil layers are alternately stacked. The consolidation of the board can be promoted by one drain, and a drain with less clogging can be formed.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view showing an embodiment of the multipurpose drain placing method of the present invention.
FIG. 2 is a perspective view of a drain material used in the multipurpose drain placing method of the present invention.
FIG. 3 is a perspective view showing a joint state of a drain material used in the multipurpose drain placing method of the present invention.
FIG. 4 is an explanatory diagram of the stitch structure of the filter material of the drain material used in the multipurpose drain placing method of the present invention.
FIG. 5 is an explanatory view of a construction machine of the multipurpose drain placing method of the present invention.
FIG. 6 is an explanatory view showing each step of the multipurpose drain placing method of the present invention.
FIG. 7 is a perspective view showing an example of cutting a drain material used in the multipurpose drain placing method of the present invention.
FIG. 8 is a perspective view showing another example of cutting the drain material used in the multipurpose drain placing method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Drain material 2 ... Drainage material 3a, 3b ... Filter 4 ... Hole 5 ... Joint 6 ... Construction machine 7 ... End block bit 8 ... Casing 9 ... Gravel mat 10 ... Liquefaction layer 11 ... Non-liquefaction layer 12 ... Heavy machine 13 ... Reader 14 ... Chuck / rotation drive device 15 ... Displacement meter 16 ... Rotational torque meter 17 ... Data recording machine 18 ... Cutting machine 19 ... Pipe 20 ... Fixing jig 21 ... Density meter

Claims (4)

Filters using a knitted or woven fabric with water permeability several times that of sand and filters using a continuous long-fiber nonwoven fabric made of synthetic resin as a raw material are made of linear synthetic resin according to changes in the soil layer of the target ground. Attached around the piled cylindrical drainage material and connected with an arbitrary length to form a single drainage material. This drainage material is built on the ground and measures against liquefaction and consolidation of soft viscous ground Multi-purpose drain placement method characterized by promoting. A large number of holes are opened according to changes in the soil layer of the target ground, a filter using a knitted or woven fabric that has water permeability several times that of sand and a filter using a continuous long-fiber nonwoven fabric made of synthetic resin. Mounted around a cylindrical plastic drainage made of synthetic resin and connected with an arbitrary length, it is formed as one drain material, and liquefaction measures and soft viscous land to build this drain material on the ground A multi-purpose drain placing method characterized by promoting consolidation of the panel. A filter using a knitted or woven fabric having water permeability several times that of sand is a mesh-like or mesh-like fabric knitted with yarn made of synthetic resin such as nylon, and uses synthetic resin as a raw material. The filter using a continuous long-fiber non-woven fabric is a continuous long-fiber non-woven fabric made of a polypropylene resin or a polyester resin having a water permeability of about 5 x ^10-1 to 1 x ^10-3 cm / sec. The multipurpose drain placement method described. When drilling or penetrating casings on construction machines, measure the drilling speed or penetration resistance of the construction machine and determine the soil layer thickness on site, so that each filter can be used in response to changes in the soil layer thickness. The multipurpose drain placing method according to any one of claims 1 to 3, wherein the length of the drain material attached is determined and adjusted on site.

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