JP2556801B2 - How to prevent sand liquefaction and ground liquefaction - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to artificially formed land such as a landfill or embankment, as well as to the geology and ground of sand where the groundwater level is high and soft in the sea or riverside land.
The present invention relates to a method for preventing liquefaction caused by an earthquake.

[0002]

2. Description of the Related Art The liquefaction of sand of this kind in the geology and ground is a phenomenon in which the geology and ground of soft sand becomes unstable like a liquid due to a sudden rise in groundwater pressure due to an earthquake. When a building such as a house or a lifeline such as a road is constructed, these collapse or collapse. As a conventional method of preventing such liquefaction, a drain pipe method and a crushed stone drain method are known.

In the above-mentioned drain pipe construction method, for example, a plastic pipe having a diameter of 10 cm and a length of 9 m, in which a large number of holes are formed, is used. It is a construction method in which a plurality of wound filter materials are buried vertically in the geology / ground of the target sand at a predetermined interval.

In the above-mentioned crushed stone draining method, a plurality of holes having a diameter of 50 cm and a depth of about 20 m are excavated at predetermined intervals in the target sand geology and ground, and crushed stones are put into the holes to be formed by tamping. It is a construction method.

In each of these conventional examples, a kind of well is dug in the sand geology and ground, and the groundwater pressure that rises at the time of an earthquake is released from the well to the surface of the ground to suppress the liquefaction phenomenon. is there.

[0006]

In the above-mentioned drain pipe construction method, the outer peripheral surface of a plastic pipe having a large number of holes is covered with a sheet-shaped filter material, and the intervals of the large number of holes are wide. Not only is drainage not possible due to a sudden increase in groundwater pressure, but the filter material corresponding to the part with holes only acts locally, significantly reducing the filter function and the filter used is woven. Since it is a cloth, it is easily clogged,
In addition, in the initial stage, fine soil particles (sand particles) pass through and accumulate in the drain pipe, which makes it impossible to cope with the rise in groundwater pressure and loses the drain pipe function. There is.

On the contrary, if the distance between the holes formed is reduced,
Although water collection improves, the strength of the pipe itself, that is, the pressure resistance to earth pressure deteriorates, and the pipe is crushed by earth pressure due to long-term burial and multiple small earthquakes, causing an emergency (Seismic intensity class of the Japan Meteorological Agency). When there is an earthquake of about 5 or more, the function cannot be fulfilled.

Further, in the above-mentioned crushed stone drain method, since crushed stones are thrown into the excavated well hole and hardened, not only the workability of the construction work is poor, but also the groundwater level rises due to rainfall and earthquakes. At times, the sand gradually enters the gaps of the crushed crushed stones and gradually fills the gaps, which also causes a problem that the function cannot be fully fulfilled in the event of an emergency.

Therefore, the conventional example has problems to be solved in terms of workability of construction and maintenance of the shape and function of the well over a long period of time.

[0010]

As a concrete means for solving the above-mentioned problems of the prior art, the present invention is to drill well holes of a predetermined size and a predetermined depth in a sand geology and ground at predetermined intervals,
With the resin strings randomly curled in these well holes, they are laminated in a hollow columnar shape having a predetermined hole along the lengthwise direction in the center part, the contact parts of the strings are welded, and the filter is attached to the outer peripheral surface. The present invention provides a method for preventing sand liquefaction and ground liquefaction, characterized in that drainage materials wound around are buried respectively. The drainage material has a porosity of 80% or more and a filter material. As the long-fiber non-woven fabric made of resin is used, the buried drainage material is a vertical direction, an oblique direction, a horizontal direction, or a combination thereof, and a crushed stone layer is provided on top of the buried drainage material. It is formed as a lid portion, and a non-water passage portion is formed in the filter material of the drainage material corresponding to the stratum.

[0011]

[Function] Since the drainage material with a porosity of 80% or more is used in the well hole, groundwater will come into the drainage material from all parts of the filter material wrapped around the outer peripheral surface. Almost no clogging phenomenon is seen,
It is possible to maintain a sufficient drainage capacity for a long period of time, and since the drainage material itself has excellent pressure resistance, it is possible to maintain the shape of the well hole for a long period of time.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in more detail with reference to the illustrated embodiment. In FIG. 1, reference numeral 1 denotes the geology and ground of sand to be prevented from liquefaction. Using a drilling device such as an auger, a predetermined size (100 to 2
00 mm) and the depth (3 to 15 m) of the well hole 2 are drilled,
A cylindrical drainage material 3 is inserted and embedded in the well hole.

The cylindrical drainage material 3 is made of a resin string, that is, a linear polypropylene of about 2 mm, which is melted by heating, extruded from a nozzle, and sequentially laminated in a curled state irregularly . Mutual contact part
The component is welded and molded into a hollow column, and is generally commercially available (trade name: hemitalone-Shinko Nylon Co., Ltd.).

The drainage material 3 has a predetermined hole 4 formed in the central portion along the length thereof, is substantially flexible and has a high pressure resistance, and the surface porosity thereof is 95-9.
7%, porosity 80-95%, load approximately 10 t / m
The porosity of 2 is 80%.

The filter material 6 is wound around and fixed to the outer peripheral surface of the drainage material 3. The filter material 6 is, for example, a polypropylene long-fiber non-woven fabric as a most preferable example.

The drilling of the well holes 2 is carried out at intervals of about 0.5 to 5 m, depending on the condition of sand geology and ground, and the drainage material 3 is inserted into each well hole 2. To do. In this case,
For example, the drainage material 3 may be inserted in advance inside the auger, and at the end of drilling, the bit at the tip may be opened to forcibly push the drainage material 3 and remove the auger.

Then, the drainage material 3 inserted in the well hole 2
The upper end portion of may be protruded a few centimeters as it is, or as shown in the figure, it may be buried slightly lower than the surface of the earth, and a lid may be formed by forming a crushed stone layer 6 on the upper portion thereof.

Further, in the sand geology / soil 1, there is a case where the impermeable layer 1a made of clay, silt or the like exists in the middle. The water-impermeable layer 1a has a very fine particle size, and the fine particles may be sequentially melted and adhered to the filter material 6, and may be sequentially deposited in the drainage material 3 to cause a substantial clogging phenomenon.

In such a case, in order to suppress the dissolution of fine particles, a material that does not allow water to pass through the outer peripheral surface of the filter material 6 at the portion corresponding to the hardly water permeable layer 1a,
For example, the non-water-permeable portion 7 formed by winding vinyl tape or the like.
To form.

The formation of the non-water-permeable portion 7 enables confirmation of whether or not the water-impermeable layer 1a is present when excavating the soil geology / ground 1 for liquefaction prevention in advance and conducting a geological survey. The non-water-permeable portion 7 may be formed by winding a vinyl tape or the like around the outer peripheral surface of the filter material 6 in consideration of the depth corresponding to the water-impermeable layer 1a.

That is, it also includes the selection of the filter material 6 according to the stratum. Particularly in the case of the water impermeable layer 1a, the filter at the position corresponding to the water impermeable layer should be prevented from entering the drainage material 3. The material 6 is blocked.

Since the specific gravity of the substance of the drainage material 3 is often smaller than 1, a weight 8 may be attached to the tip of the well hole 2 in order to prevent it from floating. The weight in this case is formed of, for example, concrete or the like, and the end portion of the drainage material 3 is embedded in the concrete before the concrete is put into the mold and hardened, so that the drainage material 3 and the weight 8 are integrated. It should be attached.

For example, in the case of a built-up land,
Perform liquefaction prevention as shown in. That is, the groundwater table 12 is also formed in the embankment 11, and the drainage material 3 is buried in a plurality of locations in the groundwater table 12 where liquefaction is likely to occur, as shown in FIG. In this case, it can be embedded vertically or obliquely.

As shown in FIGS. 3 and 4, when the house 13 is already built on the soft sand geology / ground 1,
A plurality of drainage materials 3 vertically on the circumference of the house.
And a plurality of slanted drainage materials 3 are buried from the peripheral surface of the house to the lower part of the house. Even in this case,
The filter material in the portion of the drainage material 3 which is in contact with the water-impermeable layer 1a is a water impermeable portion.

Further, as shown in FIGS. 5 and 6, before the house is built on the soft sand geology / ground 1, the entire site including the part under the floor of the house, that is, the vicinity of the foundation 14 is included. A large number of drainage materials 3 are vertically embedded in the area.

Further, also in the embankment portion 11 for roads or railroads as shown in FIG. 7, a plurality of drainage materials 3 are buried in the vertical direction and the oblique direction similarly to the above. In this case, it is more effective to bury a part of the drainage material 3 in the embankment portion 11 obliquely upward, and a drainage function can be imparted especially during rainfall.

FIGS. 8 and 9 show soft sand geology / ground 1
FIG. 8 shows examples of the roads constructed above.
In the case of, a plurality of drainage materials 3 are embedded vertically in the foundation 15 and the sidewalk 16 of the road, and a crushed stone layer 5 is formed on the upper part of the drainage material 3 to cover the side surface of the road. It is communicated with the side groove 17 provided in the. With this configuration, groundwater that has rapidly risen through the drainage material 3 can escape from the crushed stone layer 5 to the gutter 17.

In the case of the road shown in FIG. 9, a plurality of drainage materials 3 are arranged in parallel and diagonally from the side surface of the road to the lower part of the foundation portion 15.
Is buried and one end of the drainage material 3 is opened to the gutter 17, so that groundwater from the drainage material 3 escapes directly to the gutter 17. Reference numeral 18 is asphalt that forms the road surface.

In any of the above embodiments, the drainage material 3
Is buried in the soft sand geology / ground 1 vertically, diagonally or horizontally. By ejecting the groundwater pushed up by the rise in pore water pressure due to an earthquake, etc. to the surface of the earth or gutters for drainage, etc. It is possible to suppress the geology of sand and the liquefaction of the ground, and prevent the collapse or collapse of houses and roads.

Furthermore, when the drainage material 3 itself is buried,
It not only plays the role of a building pile for sand geology and ground 1, but also absorbs vibrations, suppresses subsidence and landslides of buildings, and runs trucks or dump trucks or passes trains. Of course, it also acts to mitigate the transmission of underground vibrations based on.

[0031]

As described above, the method for preventing liquefaction of sand geology / ground according to the present invention is to drill well holes of a predetermined size and a predetermined depth in the sand geology / ground at predetermined intervals. ,
In the state where the resin strings are irregularly curled in these well holes, they are laminated in a hollow cylindrical shape having a predetermined hole in the central portion along the length direction to weld the contact portions of the strings to each other, and to filter the outer peripheral surface with a filter material. By embedding the drainage materials that are wound around each other, the well hole shape is maintained in a state where water can enter from almost the entire surface of the drainage material, and the clogging phenomenon of the filter material does not occur even for a long period of time. Not only is it rarely seen , but especially when groundwater pressure is sudden due to an earthquake, etc.
When it ascends sharply, groundwater is sped up through the hole in the center of the drainage material.
Since it drains or gushes to the outside gently,
It does not cause the phenomenon of liquefaction. And the structure of drainage material
It has an excellent effect that it is easy to form and can be provided at low cost, and that once the drainage material is buried , it is possible to almost semipermanently suppress the sand geology and the liquefaction phenomenon of the ground.

Further, since the drainage material has a porosity of 80% or more and a long-fiber non-woven fabric made of resin is used as the filter material, it is lightweight and easy to carry or carry during the construction. Since the drainage material itself is elastic and has excellent pressure resistance, construction work is easy, and the well shape can be maintained for a long period of time, and the drainage function is not lost. .

The buried drainage material is vertical, oblique or horizontal, or a combination thereof, and a crushed stone layer is formed on top of the buried drainage material to form a lid. , The geology of sand under various conditions
Even in the ground, it has an excellent effect that construction work for preventing liquefaction is possible.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an essential part showing a method of preventing liquefaction of sand geology and ground according to the present invention.

FIG. 2 is an explanatory diagram showing an example in which the same liquefaction prevention method is applied to an embankment land reclamation site.

[Fig. 3] The same liquefaction prevention method is used for the geology of sand with a house built
It is explanatory drawing which shows schematically the side surface of the example applied to the ground.

FIG. 4 is an explanatory view showing a plane of FIG.

FIG. 5 is an explanatory view schematically showing a side surface of an example in which the liquefaction prevention method is applied to sand geology / ground before building a house.

FIG. 6 is an explanatory view showing a plane of FIG.

FIG. 7 is an explanatory view schematically showing a side surface of an example in which the same liquefaction prevention method is applied to embankment for roads or railways.

FIG. 8 is an explanatory diagram schematically showing a side surface of an example in which the same liquefaction prevention method is applied to a road.

FIG. 9 is an explanatory view schematically showing a side surface of another example in which the liquefaction preventing method is applied to a road.

[Explanation of symbols]

 1 Sand Geology / Soil 1a Impervious layer 2 Well hole 3 Drainage material 4 Hole in the center 5 Crushed stone layer 6 Filter material 7 Water impermeable part 8 Weight 11 Filled part 12 Groundwater surface 13 Building 14 Foundation 15 Foundation part 16 Sidewalk 17 Gutter 18 Asphalt

 ──────────────────────────────────────────────────続 き Continuing from the front page (73) Patent holder 592195056 Kazuo Kamura 5-11-2 Hanazono Ward, Hanamigawa-ku, Chiba Chiba Prefecture (73) Patent holder 592195067 Osamu Fukaoka 3-12-3-Masa, Mihama-ku, Chiba Chiba 207 (73) Patent holder 592195078 Asahi Construction Co., Ltd.3-1, Machimachi, Chuo-ku, Chiba-shi, Chiba (73) Patent holder 592195089 Keisei Construction Co., Ltd. 4-17-3, Miyamoto, Funabashi-shi, Chiba-ken (73) Patent holder 592195090 Industrial Construction Co., Ltd. 2-13-12 Minamicho, Chuo-ku, Chiba City, Chiba Prefecture (73) Patent holder 592195104 Abe Construction Co., Ltd. 832-7, Ro, Asahi-shi, Chiba Prefecture (73) Patent holder 592195115 Shirai Construction Co., Ltd.Chiba 2-4-21 Tsudanuma, Narashino (73) Patent holder 592195126 Nozaki Construction Co., Ltd.223-3 Shinko, Mihama-ku, Chiba-shi, Chiba (72) Inventor Kenji Ishihara Nara, Midori-ku, Yokohama-shi, Kanagawa 2415-123 (72) Inventor Hisashi Musai 397-22 Sannocho, Inage-ku, Chiba-shi, Chiba Prefecture (72) Inventor Yoshitada Yoshida 401-196 Jiyugaoka, Kukizaki-cho, Inashiki-gun, Ibaraki Prefecture (72) Inventor Takashi Kusuda Chiba-shi, Chiba Prefecture Omori-machi, Chuo-ku 260-141 (72) Inventor Kazuo Kamura 5-11-2 Hanazono, Hanamigawa-ku, Chiba-shi, Chiba (72) Inventor Osamu Kazeoka 3-12-3-207 (72) Masago, Mihama-ku, Chiba-shi Inventor Kennori Matsumoto 3-1 Asahi Construction Co., Ltd. 3-1 Chuo-ku, Chiba City, Chiba Prefecture (72) Inventor Tetsuya Ando 4-17-3 Miyamoto, Funabashi City, Chiba Prefecture Keisei Corporation (72) Inventor Kenji Ogura 2-13-12 Minamimachi, Chuo-ku, Chiba, Chiba Prefecture Construction Co., Ltd. (72) Inventor, Hibumi Abe 832-7 Ro, Asahi, Chiba Abe Construction Co., Ltd. (72) Inventor, Yasuhiko Shirai, Narashino, Chiba Prefecture 2-4-21 Tsudanuma Shirai Construction Co., Ltd. (72) Inventor Takuji Nozaki 223-3 Shinko, Mihama-ku, Chiba, Chiba Prefecture Nozaki Construction Co., Ltd. (56) References Special Rights 2-183006 (JP, A) Patent Rights 2-85414 (JP, A) JP Akira 49-31106 (JP, A) JitsuHiraku Akira 61-58227 (JP, U)

Claims (5)

(57) [Claims] 1. Wells having a predetermined size and a predetermined depth are drilled at a predetermined interval in the sand geology and ground, and these well holes are
In the center part with the resin string curled irregularly
Characterized in that the drainage materials are laminated in the shape of a hollow cylinder having predetermined holes along the length direction, the contact portions of the strings are welded, and the drainage material wound around the outer peripheral surface is embedded. How to prevent sand liquefaction and ground liquefaction. 2. The method for preventing liquefaction of sand geology and ground according to claim 1, wherein the drainage material has a porosity of 80% or more and the filter material is a resin long-fiber nonwoven fabric. 3. The method for preventing liquefaction of sand geology / ground according to claim 1, wherein the drainage material to be buried is in any of a vertical direction, an oblique direction, a horizontal direction, or a combination thereof. 4. The method for preventing liquefaction of sand geology and ground according to claim 1 or 3, wherein a crushed stone layer is formed on an upper part of the buried drainage material to form a lid. 5. The sand geology according to claim 1 or 2, wherein a non-water-permeable portion is formed in the filter material of the drainage material corresponding to the stratum.
Ground liquefaction prevention method.