JPH0441811A - How to form a drain pillar - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a drain column and a method for forming the same that are applied to a consolidation dewatering method, which is a soil improvement method for soft ground.

(Conventional technology) To improve soft and viscous soil with high water content and high fluidity,
A large number of vertical drain columns are formed at appropriate intervals in the soft ground to shorten the horizontal consolidation drainage distance in the ground, and a loaded embankment is applied to the surface of the soft ground to fill gaps in the ground due to the load. The so-called consolidation dewatering method is used to promote consolidation of the ground by increasing water pressure and draining pore water in the ground to the ground through drain pillars.

In such consolidation dewatering methods, the sand drain method and the back drain method have been known as methods for forming the drain pillars. After vertically press-fitting sand piles into the ground to the required depth, sand is supplied and filled into the steel pipe while being pulled up, thereby placing sand piles of a certain diameter (300 to 600 mmφ) into the ground at desired intervals ( The back drain method is a method in which sand piles are driven and formed in the same way as the sand drain method, but in order to shorten the time required for consolidation and drainage of the ground. The sand piles are driven at intervals of 1 to 2 m, and their diameter is also small (approximately 120 mm), and the entire sand pile is covered with a nonwoven fabric.

(The problem that the invention aims to solve! However, according to the above-mentioned consolidation dewatering method, it is not only difficult to obtain high-quality sand that can be used as a drain material, but also to keep the sand pile in a homogeneous state over its entire length. It is difficult to pour concrete, and small diameter sections or large diameter sections are formed, or partially discontinuous sections are formed, making it impossible to obtain sufficient drainage capacity.In addition, soil consolidation or progress may occur. As a result, there is a possibility that the deformation and discontinuity of the sand pile will increase.

In particular, in the former sand drain construction method, sand piles cannot stand up on their own in soft ground with high water content and high fluidity, and in addition, due to the difference in the weight of the sand and the weight of the surrounding ground, the horizontal direction of the sand piles This greatly accelerates the deformation of the water, resulting in partial discontinuity, and there are cases where the drainage effect cannot be exerted.

An object of the present invention is to provide a drain column and a method for forming the same that can solve these problems.

(Means for Solving the Problems) In order to achieve the above object, the drain column of the present invention has water-permeable cylindrical members buried in soft ground to a desired depth, and inside the water-permeable cylindrical members, each other has a surface. It is characterized in that it is formed into a columnar shape by filling a large number of foamed resin particles, which are integrally fused together, with gaps provided between the particles.

In addition, as a method for forming such a drain column, after burying a water-permeable cylindrical member to a desired depth in soft ground, a foamed resin granule obtained by melting only the surface by foaming is sent into the water-permeable cylindrical member. The method is characterized in that the surfaces of the foamed resin particles are fused and integrated within a water-permeable cylindrical member, and gaps are formed between the foamed resin particles that are not in contact with each other.

At this time, it is desirable to attach a floating resistance plate to the lower end of the water-permeable cylindrical member buried in the soft ground.

The water-permeable cylindrical member used is a non-woven fabric or a split fabric made by arranging a large number of stretched thin flat yarns in length and width and welding their intersections.

(Function) The drain material is made of foamed resin granules with a larger diameter than sand particles, and when filled in a water-permeable cylindrical member, the surfaces of adjacent foamed resin granules are fused and integrated, forming the granules. Since gaps are formed between the drain pillars, the gap ratio is significantly larger than that of sand piles, and the particle sizes of the foamed resin granules are approximately uniform, so they are uniform over the entire length of the drain pillar. In addition to exhibiting high water permeability, the drain resistance (head loss) associated with the movement of pore water in the vertical direction is extremely small, making it difficult for the phenomenon of decreased drainage efficiency to occur, which is a problem especially in deep construction. .

Furthermore, even if fine soil particles in the ground permeate the water-permeable cylindrical member, the gap ratio between the foamed resin particles is large as described above, so the fine soil particles will fill the gaps and reduce water permeability. It takes an extremely long time for this to occur, and within the normal consolidation and dewatering period, the permeability deteriorates and there is no tremor.

In addition, in the method of forming drain columns, since the foamed resin granules are lighter than sand materials, it is possible to transport them by air at low pressure, and the water-permeable cylindrical member can be connected to the water-permeable cylindrical member by simple piping from the heating foaming equipment side. Since the contact area of the foamed resin granules is fused and integrated within the water-permeable cylindrical member, the drain column is made of smooth and precise foamed resin granules and evenly has countless voids. can be formed,
The constructability of the drain pillar is improved.

In addition, by attaching a floating resistance plate to the lower end of the water-permeable cylindrical member, it is possible to prevent deformation or lifting of the drain pillar due to the buoyancy of the lightweight foamed resin granules that are the drain material during or after forming the drain pillar. It is something that can be prevented.

(Example) To explain an example of the present invention with reference to the drawings, in Figs.
The drain pillar is installed in a vertical state to the desired depth of (a), and is placed in a permeable cylindrical member (2) with a diameter of about 80 to 100-1 buried in the soft and viscous soil (a). Foamed resin granules (3) such as expanded polystyrene with a diameter of 1 to 3 ms are filled as a drain material, and the portions of adjacent foamed resin granules (3) (3) in contact with each other are subjected to primary foaming (pre-foaming) or complete foaming. Foamed resin particles that are integrally fused by heating and melting the surface due to foaming and are not in contact
3) A gap (4) is formed between the surfaces of (3).

(5) is a floating resistance plate attached to the lower end of the water-permeable cylindrical member (2), and the lower surface of the tip cap body (6) attached to the bottom of the cylindrical member (2) to close the bottom of the opening. It protrudes horizontally from the base and is press-fitted and locked into the soft and viscous soil (a).

The water-permeable cylindrical member (2) filled with countless foamed resin particles (3) as the drain material may be made of water-permeable nonwoven fabric sewn into a cylindrical shape, or as shown in FIG. , a large number of stretched thin flat yarns (2a) (2
a) are arranged vertically and horizontally at small intervals and welded at their intersections to form stretched narrow flat yarns (2a) arranged vertically and horizontally (
2a) A cloth formed into a cylindrical shape with a large number of fine rectangular pores ('7) having an average mesh size of 1.0 mm or less between them is used.

Note that reinforcing strips (8) made of polyethylene or the like may be spirally wound at regular intervals around the outer peripheral surface of the water-permeable cylindrical member C) made of such a split cloth.

Next, place the drain pillar as above on a soft and viscous land plate (a).
This section describes the method of pouring and forming the concrete vertically to the desired depth.

FIG. 3 is an overall simplified diagram of the drain column pouring and forming device, and 0ω is a pouring machine for the pouring pipe 00, which inserts and supports the pouring pipe 00 so as to be movable in the vertical direction. Installation piping 0
It is equipped with a press-fitting and extracting mechanism 021 for υ.

The tip of the supply hose 0 hot water for the foamed resin granules (3) is connected and communicated with the upper end of the opening of the pouring pipe 00, and this hose (+31 is connected to the foamed resin granules storage tank 04). The foamed resin granules (3) in the tank (b) are fed to the hose surface by a compressor.

Further, a curing and maturing tank 051 for foamed resin granules (3), a heating and foaming tank (17), and a bead-shaped unfoamed resin granules storage tank 08) are successively connected and communicated with the storage tank side.

As shown in Fig. 4, the above-mentioned pouring pipe GO has an inner diameter of 8 (
Outer tube (lla) of about 1 to 100 sv and inner diameter of 40 to 6
It has an inner and outer double tube structure with an inner tube (llb) of about 0 mm, and the upper end of the outer tube (lla) is formed with a large diameter to connect these inner and outer double tubes (11a011b) (llb). Continuing to the upper end of a water permeable cylindrical member (2) disposed at the upper end up to the lower end between the inner and outer double pipes (lla) (llb),
Remaining long water-permeable cylindrical member (2) to be used for the next pouring
A storage chamber 09) is formed in which the container is housed in a contracted state in the length direction.

In addition, when the water-permeable cylindrical member (2) is contracted and stored in this chamber side, the water-permeable cylindrical member (2) is in contact with the inner peripheral surface of the outer tube (lla), and this water-permeable cylindrical member (2) is in contact with the inner peripheral surface of the outer tube (lla). The diameter of the water-permeable cylindrical member (2) is set so that an interval is provided between the inner circumferential surface of the water-permeable cylindrical member (2) and the inner tube (llb) to allow the foamed resin granules (3) to flow. are doing.

Furthermore, there is an exhaust port (toward) with a valve at the top end of the inner pipe (llb).
is provided, and the foamed resin granules (3) are provided at the lower end of the opening.
) is covered with a backflow prevention wire mesh (21) having a large number of meshes smaller than the particle size of the particles.

Further, a disc-shaped tip cap body (6) is attached to the lower end of the opening of the water-permeable cylindrical member (2) to close the opening end.
As shown in Fig. 7.8, a detent anchor plate (22) is provided at the center of the lower surface of the anchor plate (22) to protrude downward, and tip cap bodies (
The semicircular floating resistance plates (5) (5) are arranged on the lower surface of 6), and the negative ends of these floating resistance plates (5) (5') are attached to the tip cap body (6). 23).

(24) is a rod body for rotating the resistance plate that protrudes downward from both sides of the lower end of the outer pipe (lla) of the cast pipe θ0, and is brought into contact with and engaged with one end of the floating resistance plate (6). be.

Now, the pouring machine 0ω holds the pouring pipe OD in a vertical state so that it can be raised and lowered, and the pouring pipe OD is press-fitted from the ground surface to a desired depth in the soft and viscous soil (a) using the press-fitting and extracting mechanism surface. At this time, the outer pipe (lla) and inner pipe (ll
b) The water permeable cylindrical member (2), which is disposed in an extended state through the space between them and extends to the lower end, is attached to the upper surface of the outer periphery of the tip cap body (6) attached to the lower end under the opening of the pouring pipe OD. Since it is locked to the end face, the water-permeable cylindrical member (2) is connected to the pouring pipe 0θ while preventing earth and sand from entering the pouring pipe 00 by the tip cap body (6). It can be press-fitted into a soft and viscous soil plate (a) as one piece.

After the pouring pipe θ0 is press-fitted and buried to the desired depth in the soft and viscous soil (a), when the pouring pipe OD is manually or mechanically rotated in the circumferential direction, as shown in Fig. 9.10. The semicircular floating resistance plates (5) (5) arranged on both sides of the lower surface of the cap body (6) are fixed to both sides of the lower end of the pouring pipe θθ by the round bodies (24). (2
3) Rotates outwards, press-fits into the ground, and locks. At this time, since the anchor plate (22) protruding from the center of the lower surface of the tip cap body (6) has plunged into the ground, the tip cap body (6) does not rotate together and the floating resistance plate (5) ) only opens horizontally and is press-fitted into the ground and locked.

In this way, after pouring the pouring pipe 00 into the soft and viscous ground (a), it is then temporarily stored in the storage tank 04) in the permeable cylindrical member (2) disposed inside the pouring pipe OD. The foamed resin granules (3) in the primary foamed state are fed by the compressor surface.

The foamed resin granules (3) are supplied to the storage tank (b) from the storage tank 08) side.

That is, unfoamed resin granules such as bead-shaped expandable polystyrene are put into the storage tank side, and a foaming agent is mixed therein, and then the foaming resin granules are fed into a heated foaming tank 07) to foam them. , and then supplied to the storage tank (b) through the curing and aging tank (06).

At this time, the expandable resin granules are heat-foamed by primary foaming into single-cell particles (particle size 1 to 3II11) in which only the surface is in a molten state, and a series of foaming devices such as those described above are used. Alternatively, completely foamed single-cell foamed resin granules may be supplied to the storage tank 08) from a separate foaming device. , Cast piping 0D through the supply hose side
It may be possible to feed it to the side.

In this way, when the foamed resin granules (3) are pneumatically fed into the water-permeable cylindrical member (2) from the upper end opening of the water-permeable cylindrical member (2) while maintaining the foamed resin granules at a high temperature during foaming, the water-permeable cylindrical member The foamed resin granules (3) are collected and deposited on the tip cap body (6) of (2), and the surface portions where the foamed resin particles (3) touch each other are welded and integrated, and there are gaps (4) between the surface portions that are not welded. ) will be formed.

At this time, the molten surface of the foamed resin particles (3) in contact with the inner peripheral surface of the water-permeable cylindrical member (2) is welded to the water-permeable cylindrical member (2).

On the other hand, when the pouring pipe 0υ is gradually pulled up according to the input amount of the foamed resin granules (3), the foamed resin granules (3) are inside.
The permeable cylindrical member (2), which is filled with the materials (2) in an accumulated state, is fixed in the ground by the floating resistance plate (5) installed at its lower end, so it does not rise together, and as shown in Figure 5. From the lower end of the poured pipe 0υ to the soft viscous ground plate (a
) and left in the ground (a).

Plumbing ODO inner pipe (llb) with foamed resin granules (3)
The compressed air from the compressor 0ω to be fed into the space between the cylindrical member and the water-permeable cylindrical member (2) is supplied to the inner pipe (Ilb
) rises within the inner tube (llb) through the open lower end of the tube and is discharged to the outside from the exhaust port. At this time, the inner tube (ll
Since a backflow prevention wire mesh (21) with a finer mesh than the foamed resin granules (3) is stretched over the lower end of the opening of b), the foamed resin granules (3) flow into the inner pipe (llb). It is filled and deposited in the water-permeable cylindrical member (2) separately from the transport air. Further, the foamed resin particles (3) deposited inside the water-permeable cylindrical member (2) are pressed down by the pressurized air, and the pressurized air flows through the installed pipe a.
In order to flow through the gap between the outer tube (lla) of O and the water-permeable cylindrical member (2), the water-permeable cylindrical member (
2) The frictional force is reduced, and the cast pipe 00 can be pulled up smoothly.

In this way, by accumulating the foamed resin particles (3) inside the water-permeable cylindrical member (2) while pulling up the pouring pipe θθ and welding the parts that touch each other together, a large number of cells are formed between the non-contacting cell particles. A porous drain column (1) with a gap (9) is formed up to the ground surface.

When the lifting of the cast pipe OD is completed, the said cast pipe 00
Inside, a water-permeable cylindrical member (2) necessary for the next pouring is pulled out from the storage chamber 09, and the pouring pipe θυ, which is the connection part with the upper end of the drain column (1), is in a state of being pulled out from the storage chamber 09. Cut the part that is pulled out from the bottom of the opening and attach it to the drain column (1
) The upper cap body (25) is attached to the upper end of the drain column (1), and the construction work of the - drain pillar (1) is completed (see Fig. 6).

The upper end of this drain column (1) is placed on the upper surface of a sand mat (b) laid on a soft and viscous soil plate (a).

Next, the driving machine 0ω is moved to the next drain pillar driving position, and the drain pillar (1) is constructed in the soft and viscous ground (a) again in the same manner as described above.This operation is repeated until the horizontal direction A large number of drain posts (1) are installed at regular intervals.

In this way, a large number of drain pillars (1) are installed in the soft and viscous soil platform (a) to be improved, and a sand mat (
When loading embankment (not shown) is applied through the b), the pore water contained in the soft and viscous soil plate (a) forms the permeable cylindrical member (2) forming the outer shell of the drain column (1). Countless foamed resin granules (
3) Water permeates into the gap (4) between (3), flows upward due to consolidation of the ground (a), and is discharged to the sand mat). At this time, the gap (4) between the foamed resin granules (3) (3)
) are larger than the gaps between sand grains in drain columns made of conventional sand piles, so water permeability is extremely high and drain resistance (head loss) is small, resulting in soft and viscous soil (a).
Drainage can be smoothly carried out through the gap (4) without reducing the drainage efficiency even in the deep part of the gap.

Furthermore, the drain column (1) is made up of countless foamed resin particles (3
) are welded and integrated into a columnar shape and covered with a water-permeable cylindrical member (2), so it can withstand the sinking deformation of the ground due to the progress of consolidation compared to conventional sand piles. As such, there are no discontinuous portions, and continuity is always maintained over the entire length to ensure reliable dehydration.

In addition, when a non-woven fabric is used as the water-permeable cylindrical member (2), the non-woven fabric performs a filtration action through the gaps between the fibers caused by the entanglement of the fibers. Although it is possible to allow only pore water to pass through without passing fine particles of mud, its relatively thick thickness increases resistance to water passage, and soil particles remain and accumulate between the fibers on the surface of the filter. However, in the case of the water-permeable cylindrical member (2) formed from the above-mentioned split cloth, it is thin and strong, and moreover, the cross-section of the cuts provided in the stretched film is
The large number of pores formed by polymerization always maintain a constant size and shape, resulting in extremely low resistance to water passage, allowing water to permeate through the thin pores quickly and easily, providing smooth drainage over a long period of time. This is preferable because it can be done.

(Effects of the Invention) As described above, according to the drain column of the present invention, a water-permeable cylindrical member that reaches a desired depth is buried in soft ground, and the surfaces of the water-permeable cylindrical member are fused and integrated with each other within the water-permeable cylindrical member. Since it is formed by filling a large number of foamed resin granules with gaps between the granules and forming a columnar shape, the foamed resin granules with approximately uniform particle sizes The gaps formed always maintain a constant size without deformation, and the gap ratio is significantly larger than that of sand piles.
Uniform and high water permeability can be achieved over the entire length of the drain column, and in addition, drain resistance due to vertical pore water movement is extremely small, allowing drain columns to be installed deep in soft and viscous soil. Even when concrete is poured, smooth dewatering is achieved without causing a decrease in drainage efficiency.

Furthermore, even if fine soil particles in the ground permeate the water-permeable cylindrical member, the gap ratio between the foamed resin particles is large as described above, so the fine soil particles will fill the gaps and reduce water permeability. It takes an extremely long time to dewater, and there is no risk of deterioration of water permeability within the normal consolidation dewatering period. Therefore, even in consolidation dewatering using deep drain columns, the dewatering effect can be maintained for a long period of time. It is possible to perform reliable ground improvement, and
Drain columns are formed into a columnar shape by welding and integrating countless foamed resin granules, and are covered with a water-permeable cylindrical member. Unlike sand piles, there are no discontinuous parts, and continuity is always maintained over the entire length, resulting in smooth dewatering.

In addition, as a method for forming such a drain column, after burying a water-permeable cylindrical member to a desired depth in soft ground, a foamed resin granule obtained by melting only the surface by foaming is sent into the water-permeable cylindrical member. The foamed resin granules are fed and filled, and the surfaces of the foamed resin granules are fused and integrated within the water-permeable cylindrical member, and gaps are formed between the foamed resin granules that are not in contact with each other. Because it is lightweight compared to other materials, it is possible to transport the air at low pressure, and it is possible to supply the foamed resin into the water-permeable cylindrical member through simple piping from the heating and foaming equipment side. Since the contact portions of the granules are fused and integrated, it is possible to reliably form a drain column made of the foamed resin granules that is smooth and precise, and the workability of the drain column is improved.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and Fig. 1 is a simplified longitudinal sectional front view of a drain column installed in a soft and viscous soil.
The figure is a partially enlarged sectional view, Figure 3 is a simplified side view of the entire device showing the construction status of the drain pillar, Figures 4 to 6 are simplified longitudinal sectional front views showing the construction order, and Figure 7 is the pouring. A longitudinal sectional front view showing the floating prevention means of the drain column at the lower end of the pipe, Fig. 8 is a cross-sectional bottom view thereof, Fig. 9 is a longitudinal sectional front view showing the floating resistance plate in an open state, and Fig. 10 is its transverse bottom view. It is a diagram. (1)...Drain column, (2)...Water permeable cylindrical member, (3)...Foamed resin granules, (4)...Gap, (
5)...Floating resistance plate, (6)...Tip cap body,
0ω...Pouring machine, OD...Pouring piping, (11a)
(llb)...Internal and external tubes, ■...Storage chamber, (a)...
・Soft viscous land plate. →be 1 hardabe J

Claims (5)

[Claims] (1) A water-permeable cylindrical member is buried in soft ground to a desired depth, and within the water-permeable cylindrical member, a large number of foamed resin granules whose surfaces are fused and integrated are placed with gaps between the granules. A drain column characterized in that it is formed into a columnar shape by being filled with a drain column. (2) The drain column according to claim 1, wherein the foamed resin granules are primarily foamed polystyrene beads. (3) A drain column characterized in that the water-permeable cylindrical member is formed from a non-woven fabric or a split fabric made by arranging a large number of stretched thin flat yarns vertically and horizontally and welding their intersections. (4) After burying the water-permeable cylindrical member to a desired depth in soft ground, the foamed resin granules, which are formed by foaming and melting only on the surface, are fed and filled into the water-permeable cylindrical member. 1. A method for forming a drain column, which comprises fusing and integrating the surfaces of foamed resin granules within the container and forming gaps between the foamed resin granules that are not in contact with each other. (5) The method for forming a drain column according to claim 4, characterized in that the water-permeable cylindrical member having a floating resistance plate attached to its lower end is buried in soft ground.