JP5813995B2 - Method of placing drain material for liquefaction countermeasures - Google Patents

Description

  The present invention relates to a placement method for embedding a liquefaction countermeasure drain material in soft ground or the like.

  Conventionally, as a countermeasure for liquefaction in soft ground, sand ground, etc., for example, a drain material is placed on a saturated loose sand ground with a drain placing device as shown in FIG. A drainage method (grid drain method, drain pipe method) that is applied over the entire surface and quickly dissipates excess pore water pressure during an earthquake is known. The drain material used in this construction method is, for example, about 150 mm wide and 30 mm thick. The drain material is rolled up on a drum at a factory and transported to the site by a truck or the like. The drain material is attached to a take-up reel in the drain placing device, passed through a mandrel which is a guide body for embedding, and then placed in the ground together with the mandrel using a hydraulic device.

  Due to the presence of the drain material, pore water in the soil is collected and drained by the drain material at the time of an earthquake, and liquefaction is prevented. In addition, what is described in patent document 1 and patent document 2 is known as a prior art example of a liquefaction prevention construction method and a drain material.

Japanese Patent Laid-Open No. 01-125415 Japanese Unexamined Patent Publication No. 01-97715

  However, in the conventional method of placing a drainage material for countermeasures against liquefaction, it is necessary to use a drainage material having a large water flow capacity in order to quickly dissipate excess pore water pressure during an earthquake. In placing the drain material, since the drain material is inserted into the mandrel as the guide body, the width of the drain material is appropriately about 150 mm, and it is difficult to further increase the width. On the other hand, when the thickness of the drain material is increased, there is a problem that the volume reduction amount due to the restraining pressure in the ground increases. Therefore, if ribs are installed on the wall surface of the drain material in order to reinforce the strength of the drain material, it becomes difficult to wind it up in a roll shape, so that it is necessary to process slits, and it takes time and costs increase. There is a problem. The liquefaction countermeasure drain material placing method according to the present invention has been proposed in order to solve such problems.

The gist of the present invention for solving the above-mentioned problems of the method for placing a liquefaction countermeasure drain material according to the present invention is to provide a drain material having a length that can be transported by a transportation means. The drain material is transported to a placement site by means of transportation, the drain material is extended to a desired length by a connecting tool to form a buried drain material, and a hanging bracket is attached to one end of the buried drain material. The rope is inserted from the upper opening to the lower opening of the mandrel in the drain placing device, the leading end of the rope is connected to the hanging bracket of the burying drain material, and the rear end side of the rope Pull the buried drain material into the mandrel for storage,
An anchor plate is attached to the lower end of the buried drain material, the mandrel and the buried drain material are press-fitted into the ground by the drain placing device, and then the mandrel is pulled up to the ground to bring the buried drain material into the ground. Embed and remove the rope from the hanging bracket at the tip of the burial drain material above the ground, then connect the drain material and repeat the subsequent steps from the burial drain material formation process to burial on the ground to be improved In the placement method of the drainage material for liquefaction measures to bury the drain material for use,
The mandrel of the drain driving device is inclined with respect to the ground by the mandrel support device when pulling the rope and pulling the burying drain therein.

According to the liquefaction countermeasure drain material placing method of the present invention, since the drain material having a high water passage capacity is used, the pore water pressure can be quickly dissipated. In addition, it becomes possible to bury the drain material with a wider placement interval, which is an economical measure for liquefaction.
Since the drain material can be formed to a desired length with a connecting tool in accordance with the placement depth, there is no waste, and one or one can be placed with the drain placement apparatus, thereby improving the construction efficiency. Furthermore, in the past, the slit material was processed to wind the drain material into a roll shape, but the drain material of the present invention does not require the processing, so it is possible to use a drain material that is less expensive than the conventional one. It has the excellent effect of being able to do it.

It is a perspective view of the drain material 1 used for the placement method of the drain material for liquefaction measures concerning this invention. In the method for placing a liquefaction countermeasure drain material according to the present invention, a side view (A) showing a state of transporting a regular drain material 1 by a truck 8 and a drain material 1 a for burial were formed. It is a side view (B) of the state. They are the side view (A) of the anchor plate 2a in the connection tool 2, and a front view (B). They are the side view (A) of the connection plate 2b in the connection tool 2, and a front view (B). They are the side view (A) of the head cap 2c in the connection tool 2, and a front view (B). It is a perspective view of the state which is preparing to insert the draining material 1a for embedding in the drain placement apparatus 5. FIG. It is a perspective view of the state where the leader 5a of the drain placing device 5 is inclined obliquely. FIG. 3 is a cross-sectional view of a state in which a draining material 1a is embedded in the ground 7 with a drain driving device 5; It is a perspective view which shows the placement method of the drain material which concerns on a prior art example.

  As shown in FIGS. 1-A and 1-B, the liquefaction countermeasure drain material placing method according to the present invention is such that the drain material 1 having a large water flow section is linear, and the transportation means such as a truck 8 is used. It is formed into one that can be carried by The drain material 1 is directly attached to the mandrel 4 and embedded in the ground 7 with a large interval.

  As shown in FIG. 1-A and FIG. 1-B (A), a drain made of, for example, a hard synthetic resin (semi-hard vinyl chloride resin) that cannot be wound into a roll and has appropriate flexibility. The material 1 is formed as a drain material having a length not longer than the length that can be conveyed by the truck 8 as a transportation means (for example, about 5 m to 8 m). The flexibility of the drain material is, for example, about a radius of curvature R = 3 m to 5 m. In such a case, it is possible to improve usability by preparing about 3 to 4 types of the drain material 1 in advance at the factory as 2 m, 3 m, 5 m, and 8 m standard objects.

  As shown in FIG. 1-A, the drain material 1 has a rectangular cross section, a width of 165 mm, a thickness of about 30 to 50 mm, and a long cylinder in one direction. It consists of a water-permeable material 1b in which the wide surface 1f that faces is a water-permeable plate surface, and a nonwoven fabric (olefin-based mesh) 1c that covers the surface of the water-permeable material. Inside the water-permeable material 1b, a plurality of ribs 1d are arranged in parallel along the longitudinal direction at equal intervals in the width direction. Thereby, the water flow path 1e is formed in a longitudinal direction. The wide surfaces 1f and 1f facing each other are provided with a large number of water passage holes 1g communicating with the water passage 1e. The drainage coefficient of the drain material 1 is about 500 to 700 (cm / sec).

  Further, in order to make the drain material 1 have an appropriate length to be embedded in the ground 7, a connection tool 2 is prepared. As shown in FIGS. 2A to 2C, the connector 2 is an anchor plate 2a (see FIG. 2) for connecting the drain material 1 as appropriate to form a buried drain material 1a having a desired length. 2-A), a connection plate 2b (FIG. 2-B), and a head cap 2c (FIG. 2-C).

  Each of the anchor plate 2a, the connection plate 2b, and the head cap 2c in the connector 2 is provided with a plurality of reverse protrusions 2d that prevent it from coming out in the reverse direction after being inserted. The anchor plate 2a is provided with a flange 2e for preventing co-raising.

  As described above, the draining material 1 and the connection tool 2 are prepared in advance, and the placing method of the present invention will be described. First, as shown in FIG. 1-B (A), the drain material 1 is carried to a placement site by a truck 8 which is a transportation means. A straight drain material 1 is used to carry a necessary number of standard objects in a plurality of types.

  As shown in FIG. 1-B (B), the connecting tool 2 is used to form a required number of buried drain materials 1a having a required length to be embedded in the ground 7.

  Next, the hanging metal fitting 3 is attached to one end of the burying drain material 1a (the side that becomes the upper position when buried). As shown in FIG. 3, the rope 6 is inserted from the upper opening to the lower opening of the mandrel 4 in the drain placing device 5, and the tip of the rope 6 is connected to the hanging fitting 3 of the burying drain material 1a. Put on.

  As shown in FIG. 4, the mandrel 4 of the drain placing device 5 is inclined with respect to the ground by the leader 5a, which is a mandrel support device, when the rope 6 is pulled and the burying drain 1a is pulled in. . In this way, the flexible burying drain 1a can be easily drawn into the mandrel 4.

  Then, by pulling the rear end side of the rope 6, the burying drain material 1 a is drawn into the mandrel 4 and stored, and the anchor plate 2 a is attached to the lower end of the burying drain material 1 a. Thereafter, as shown in FIG. 5, the mandrel 4 and the buried drain material 1 a are press-fitted into the ground 7 by the drain placing device 5.

  Thereafter, the mandrel 4 is pulled up to the ground, and the burying drain material 1 a is buried in the ground 7. The rope 6 is removed from the hanging metal fitting 3 at the tip of the burying drain material 1a on the ground and diverted to another burying drain 1a.

  Thereafter, the drain material 1 is connected at the site, and the subsequent steps from the step of forming the buried drain material 1a are repeated to embed the buried drain material 1a in the improvement target ground 7.

  The method for placing the drainage material for liquefaction measures according to the present invention is related to the improvement work of the soft ground, but is not limited to this and can be applied to various improvement methods.

1 drain material, 1a buried drain material,
1b water-permeable material, 1c non-woven fabric,
1d rib, 1e waterway,
1f wide surface, 1g water vent,
2 connectors,
2a Anchor plate, 2b Connection plate,
2c head cap, 2d reverse projection,
2e flange,
3 Hanging bracket,
4 Mandrels,
5 Drain placing device, 5a Support device (leader),
6 ropes,
7 Ground,
8 tracks.

Claims (1)

A flexible drain material is formed as a drain material having a length that is less than or equal to the length that can be transported by transportation means, the drain material is transported to the placement site by transportation means, and the drain material is extended to a desired length by a connector. Then, a drain material for burial is formed, a hanging bracket is attached to one end of the drain material for burial, and a rope is inserted from the upper opening to the lower opening of the mandrel in the drain placing device, and the tip of the rope is attached. It is attached to the hanging bracket of the buried drain material, and the buried drain material is drawn into the mandrel by pulling the rear end side of the rope, and stored.
An anchor plate is attached to the lower end of the buried drain material, the mandrel and the buried drain material are press-fitted into the ground by the drain placing device, and then the mandrel is pulled up to the ground to bring the buried drain material into the ground. Embed and remove the rope from the hanging bracket at the tip of the burial drain material above the ground, then connect the drain material and repeat the subsequent steps from the burial drain material formation process to burial on the ground to be improved In the placement method of the drainage material for liquefaction measures to bury the drain material for use,
The mandrel of the drain driving device is inclined with respect to the ground by the mandrel support device when pulling the rope and pulling the burial drain into it,
A method for placing a drainage material for liquefaction measures characterized by the above.

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