JPH01226919A - Improvement of weak ground - Google Patents

Abstract

PURPOSE:To prevent the clogging of the inside of a gravel pile by filling a long-sized bag body made of a water-permeable sheet with gravel in a bagging manner, also laying the water-permeable sheet on the head section of the gravel pile on a poor subsoil and filtering sand, etc., by the water-permeable sheet. CONSTITUTION:A required number of gravel piles 2 acquired by filling reticular bag bodies 1 made of a synthetic resin finer than the grain size of gravel G with gravel G and bagging gravel are buried into a poor subsoil W. The gravel piles 2 are buried, and a filter material 3 composed of a reticulate sheet consisting of the same net material as the bag body 1 is laid onto one surface so as to be brought into contact with the head sections of each gravel pile 2 on the top face of the poor subsoil W. A gravel mat 4 made up of gravel G having the same grain size as gravel G in the gravel piles 2 and having required height is formed on the filter material 3.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for improving soft ground, and in particular, it is necessary to use gravel (gravel, crushed stone, The present invention relates to a method and device for burying piles made of gravel (gravel, mine slag) (hereinafter referred to as gravel piles), draining moisture in soft ground from the gravel piles, and thereby preventing liquefaction of the original sand.

(Prior Art) Conventionally, in this type of construction method, gravel made of gravel, crushed stone, etc. was formed into columnar shapes in a completely random manner without considering their precision distribution.

(Problem to be solved by the invention) Gravel used in this type of construction method is required to have sufficiently high water permeability to the original ground sand, but when it flows into the gravel pile, it becomes clogged inside the pile. It is necessary to prevent this from happening. However, in conventionally formed gravel piles, the grain size composition of the gravel exhibits a completely random distribution when viewed in the cross section of the pile.
Sand from the surrounding ground easily flows into the gravel pile along with water, causing clogging inside the pile (this has the problem of inhibiting the water absorption function of the gravel pile and preventing sufficient drainage). .

In view of the above-mentioned problems, an object of the present invention is to prevent clogging inside the gravel pile, to fully exhibit its water absorption function, and to enable effective drainage. A further object of the present invention is to effectively perform drainage on the upper surface side of the soft ground in which gravel piles are buried.

(Means for solving the problem) In order to achieve the above purpose, in the construction method of the present invention,
A long bag made of a water-permeable sheet is filled with gravel, such as gravel, and then the gravel pile is buried in soft ground, and then a water-permeable bag similar to the bag described above is placed on top of the soft ground. A flat filter material made of a rubber sheet is laid so as to be in contact with the head of the gravel pile, and a gravel mantle made of gravel similar to the bagged gravel pile is formed on this filter material. .

(Function) When the moisture in the soft ground is absorbed into the gravel pile, the sand, etc. contained in the moisture is reduced by the water-permeable bag, and only soil particles with extremely small particle sizes enter the inside of the pile. . In this way, the soil particles that have entered the pipe inside the pile are sucked upward together with moisture without clogging the drain layer. In addition, a flat filter material is laid on the top surface of the soft ground in contact with the head of the gravel pile, and a gravel muff is deposited on top of this, so water absorbed from the gravel pile is filtered again by the filter material. At the same time, when water containing sand from the nose gravel pile on the top side of the ground is absorbed into the gravel mat, the sand, etc. is filtered by the filter material to prevent clogging of the gravel mantle. .

(Example) An example of the method of the present invention will be described with reference to the drawings. As shown in Figure 1, a mesh made of synthetic resin (e.g. vinyl chloride) with a finer grain size than the grain size of the gravel to be filled. A required number of gravel piles 2, which are made by filling a bag body 1 with gravel G made of gravel or crushed stone, are buried in the soft ground ZW. After burying the bagged gravel piles 2 in this way, a filter material 3 made of a net-like sheet of the same net material as the bag body 1 is placed on the upper surface of this soft ground W so as to be in contact with the head of each gravel pile 2. A gravel mat 4 of a required height is formed on the filter material 3, which is made of gravel G having the same particle size as the gravel G of the gravel pile.

By burying the gravel pile P in the soft ground 51w as described above and providing the gravel mat 4 on the top surface of the ground W with the flat filter material 3 interposed therebetween, moisture in the soft ground W can be removed from each gravel pile. By passing through the mesh bag 1 of the pile 2, sand, etc. with relatively large grain size in the water is transferred to the gravel pile 2.
are prevented from entering the interior of the gravel pile 2, and only particles with extremely small diameters flow into the gravel pile 2 and are sucked up through the gravel pile 2 to the upper surface of the ground @W. The water absorbed on the upper surface side of the ground W is filtered again by the planar filter material 3, sucked up to the gravel mat 4, and drained to an appropriate place via the gravel mat 4.

In this case, the gravel mat 4 also absorbs moisture including sand on the upper surface of the ground W, but due to the presence of the filter material 3, a filtration action is performed in the same manner as described above, and the gravel mat 4 is not clogged. .

Next, in carrying out the above-mentioned construction method, an apparatus for bagging gravel G and burying bagged gravel piles P in soft ground W will be described.

As shown in Fig. 2, this device consists of a league (not shown)
A rotary casing 7 with a screw having a shoe 6 at the lower end is rotatably hung from the lower part of the machine frame 5 suspended from the machine frame 5, and a fixed casing 8 is inserted and deployed over the entire length into the rotary casing 7. At the lower end of the gravel supply hopper 9 provided on the upper side of the machine frame 5, a cylindrical forming chute 10 is integrally connected and suspended directly above the fixed casing 8. An on-off valve 12 is provided which is driven by a cylinder 11 to open and close the entrance of the molding chute 10, and a forming plate 13 is further provided on the upper side of the molding shade 10, and a rolled band-shaped net sheet 14 is passed from this forming plate 13. The mesh sheet 14 is supplied to a forming chute 10 and formed into a cylindrical shape while aligning both longitudinal edges of the net sheet 14 with each other on the outer circumferential surface of the forming chute 10. Then, a longitudinal heat sealer 15
The overlapping edges of the mesh sheets 14 are thermally welded to continuously form a cylindrical mesh bag 1, and the formed mesh bag 1 is conveyed downward by the feed rollers 16 and 16 on both sides/pair. and is inserted into the fixed casing 8.

Note that the rotating casing 7 is driven by a rotational drive mechanism (not shown), and the feed roller 16 is driven by a motor 17.

When using such a configuration device, a roll-shaped net sheet 14 is fed out, the leading end of which is fed through a support roller 18 to a forming plate 13, and further fed to a forming chute 10 via this forming plate 13 to form a cylindrical shape. The rotary casing 7 is formed into a shape and held between the feed rollers 16°16.Then, while rotating the rotary casing 7 in the direction of the arrow as shown in FIG. 2A, it is penetrated into the soft ground W.
On the other hand, the vertical heat sealer 15 is moved oppositely toward the forming shoe 10, and the mesh sheet 14 is formed into a cylindrical shape.
After forming the bag l by heating and welding the overlapping edges on both sides by the length of the heat sealer 15, the heat sealer 15 is
is retracted to its original position, and the bag l is removed by a length approximately corresponding to the length of the bag 1 formed by welding and joining.
is sent down by the feed roller 17.17, and then the heat sealer 15 is again moved opposite to the forming chute 10 to weld and join the overlapping edges on both sides of the mesh seam 4. The bag 1 is inserted into the fixed casing 8 while being formed almost continuously (see Fig. 4 A@). Note that the cylindrical bag 1 that is formed first is being formed. The tip of the bag 1 is tied up with a string or the like (it is necessary to do so, and in order to easily and reliably insert the bag into the fixed casing 8, after the tip of the bag 1 is tied up, the opening/closing valve 12 is Open the bag and pour a small amount of gravel G in the hopper 9 into the bag 1 as shown in FIG. 2A to use it as a weight.

When the rotating casing 7 reaches a predetermined depth in the ground W and the tip of the bag l reaches the lower end of the fixed casing 8, the on-off valve 12 is opened as shown in FIG. 2B. The gravel G in the gravel supply hopper 9 is fully filled into the bag body 1 through the forming chute IO. After filling the bag 1 with the label G, the bag 1 is cut with a canter or the like below the forming chute 10. after that,
As shown in Fig. 2C, the rotary casing 7 is rotated in the opposite direction to the direction in which it was drilled, and the fixed casing 8 is pulled out from the ground W, and only the bag body 1 filled with gravel G is placed into the ground W. A gravel pile 2 as shown in Fig. 1 is created by leaving it behind.

In this example, while forming the cylindrical bag at the construction site,
Although the case of filling with gravel has been described, a ready-made bag manufactured in advance at a factory may also be used.

In addition, although a bag formed of a net sheet was used in the example,
A bag made of any suitable sheet material other than the net sheet can be used as long as it has the desired water permeability.

(Effects of the Invention) According to the present invention, especially in sandy soft ground, sand, etc. in the original ground is filtered by the water-permeable bag of the gravel pile, and only soil particles with extremely small particle sizes enter the interior together with water. Because of the inflow, it is difficult for clogging to occur inside the gravel pile, so the permeability and drainage functions of the gravel pile are fully utilized, and liquefaction of the original ground can be effectively prevented.
In addition, the planar filter material laid on the top surface of the ground filters moisture sucked up through the gravel piles or existing on the top surface of the ground, which prevents clogging inside the gravel mat. Good drainage can be done.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional explanatory diagram showing an embodiment of the present invention, Fig. 2A-
C is an explanatory diagram showing an example of forming a bagged gravel pile. G...Gravel, 1...Bag body, 2...Gravel pile, 3...Filter material, 4...Gravel mat.

Claims (1)

[Claims] A long bag made of a water-permeable sheet is filled with gravel, such as gravel, and then the gravel pile is buried in soft ground, and then a water-permeable bag similar to the bag described above is placed on top of the soft ground. A flat filter material made of a rubber sheet is laid so as to be in contact with the head of the gravel pile, and a gravel mat made of gravel similar to the bagged gravel pile is formed on the filter material. Ground improvement method.