JPH0742692B2 - Protective method for structures constructed on sand ground that tends to liquefy - Google Patents

Description

TECHNICAL FIELD The present invention relates to a protection method for a structure constructed on sand ground that is likely to be liquefied, and more particularly to a method for preventing the structure from sinking or rising.

<Conventional technology> When building structures are built on sand ground, excess pore water pressure rises in the ground at the time of an earthquake, and the sand ground is liquefied, causing damage to these structures that sink or float. Often occur in earthquakes.

As measures against such problems, there are ground improvement, gravel drains and groundwater level lowering construction methods, but they are not often used because of restrictions on site conditions and problems in long-term maintenance.

Then, as a method for solving such a problem, for example, there is a liquefaction prevention structure as disclosed in JP-A-58-127823.

However, there is a problem described below when the structure disclosed in this publication is specifically applied to the protection of the structure.

<< Problems to be Solved by the Invention >> That is, in the liquefaction prevention structure of the above publication, gravel is formed on the outer periphery of the permeable concrete column in the foundation ground supporting the structure.
A certain number of drain columns are constructed by permeable walls made of fine stones, slag, and other materials, and the drain columns prevent the increase of excess pore water pressure. The installation is not only difficult to construct, but also expensive to construct.

Further, in the structure in which the drain pillar is provided below the structure, there is a problem that the structure floats due to the pressure of water rising in the drain pillar when the ground is liquefied.

The present invention has been made in view of such conventional problems, and an object of the present invention is to easily and economically construct a sand ground that can prevent the sinking or rising of a structure and can be liquefied easily. The purpose is to provide a protection method for the structures constructed in.

<< Means for Solving Problems >> In order to achieve the above-mentioned object, the present invention is directed to the area of the ground foundation in the horizontal direction below the ground foundation of the structure constructed on the sand ground that is easily liquefied. While forming a gravel layer that has a corresponding area and doubles as paving masonry, install one or more drainage pipes that extend horizontally from this gravel layer through the underground foundation, and the sand ground The excessive pore water generated in 1) is collected in the gravel layer and then naturally drained from the drain pipe to the ground.

<Operation> According to the protection method with the above configuration, when seismic force acts on the sand ground and the pore water pressure rises, excess pore water is collected in the gravel layer and then buried in the underground foundation of the structure. Since it is quickly drained to the ground from the horizontally extending drain pipe, the rise of pore water pressure and liquefaction are suppressed in the ground under the ground foundation, and the subsidence and uplift of the structure are effectively prevented.

<Example> Hereinafter, a preferred example of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a method for protecting a structure constructed on sand ground which is easily liquefied according to the present invention.

The structure 10 shown in the figure is located on a sand ground 12 that is easily liquefied, and its foundation 14 is provided in the ground slightly dug from the surface of the ground.

The construction of the protective construction method is performed before the construction of the structure 10, and first, the gravel layer 16 having a predetermined thickness which also serves as paving stone is formed below the foundation 14 of the structure 10.

As the gravel layer 16, gravel having a predetermined size is used, and the gravel layer 16 is spread over a size corresponding to the area of the foundation 14 to be constructed.

When the gravel layer 16 is formed in this manner, the foundation is formed above it.
The structure 10 is constructed by constructing 14 and constructing the side wall 18, the slab 20, etc. of the structure 10 on the foundation 14.

Then, during construction of the foundation 14, one or a plurality of drain pipes 22a to 22c extending in the horizontal direction are installed therein.

In this embodiment, three hollow pipe-shaped drain pipes 22a to 22c are used.
Is installed, and one end of each drainage pipe 22a-c is a gravel layer 1
Located at 6, the other end is a rainwater drainage mass 24 provided above ground.
It is open to.

Now, with the protection method constructed as above, the sand ground 12
When the pore water pressure rises due to the seismic force acting on the ground, excess pore water is collected in the gravel layer 16 and then buried in the foundation 14 of the structure 10 and drained from the drain pipes 22a to 22c extending in the horizontal direction. twenty four
Since the water is quickly drained, the rise of pore water pressure and liquefaction in the ground below the underground foundation 14 are suppressed, and the subsidence and uplift of the structure 10 are effectively prevented.

<< Effects of the Invention >> As described in the above embodiments, according to the method for protecting a structure constructed on the sand ground that is liquified easily according to the present invention, the structure constructed on the sand ground that is easily liquefied Form a gravel layer that has an area equivalent to the area of the underground foundation in the horizontal direction below the underground foundation and also serves as paving stone, and extends horizontally from this gravel layer through the underground foundation. Since one or more drainage pipes are installed and excess pore water generated in the sand ground is collected in the gravel layer, this is naturally drained to the ground from the drainage pipe, so that in the ground below the ground foundation. Liquefaction associated with the increase of pore water pressure is relaxed and eliminated, and the subsidence and uplift of the structure are prevented.

In the protection method, a gravel layer that doubles as paving stone is formed below the foundation of the structure, and extends almost horizontally from this gravel layer.
Since only one or a plurality of drainage pipes are installed, the construction can be performed easily, which is advantageous in terms of economy.

[Brief description of drawings]

 FIG. 1 is a sectional view showing an embodiment of the method of the present invention. 10 …… Structure 12 …… Sand ground 14 …… Foundation 16 …… Gravel layer 22a ～ c …… Drainage pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeki Tsuchiyama 1 No. 20 Kitakanyama, Otaka-cho, Midori-ku, Nagoya-shi, Aichi Chubu Electric Power Co., Inc. Research Institute (72) Inventor Makoto Hayakawa Nagoya, Aichi 20-1 Kitakanyama, Otakamachi, Midori-ku Chubu Electric Power Co., Inc. Research Institute (72) Inventor Yozo Goto 5-30-13-101 Kugayama, Suginami-ku, Tokyo (72) Inventor Tadao Koide Sayama, Saitama Prefecture 468-30 Mizuno, Ichino (72) Inventor, Ho Ho Endo 3-1-4-1-404, Azamino, Midori-ku, Yokohama, Kanagawa Prefecture (72) Makoto Toriihara 5-28-9, Musashidai, Hidaka-cho, Iruma-gun, Saitama Prefecture (72) ) Inventor Joji Ejiri 4-640 Shimoseido, Kiyose City, Tokyo (56) Reference JP-A-55-142815 (JP, A)

Claims (1)

[Claims] 1. A gravel layer that doubles as a masonry is formed in a horizontal direction below a ground foundation of a structure constructed on a sand ground that is easily liquefied and has an area corresponding to the area of the ground foundation. At the same time, one or a plurality of drain pipes extending horizontally from the gravel layer through the underground foundation are installed, and excess pore water generated in the sand ground is collected by the gravel layer. A method for protecting a structure constructed on sand ground that is easily liquefied, characterized in that the water is naturally drained from the drainage pipe to the ground.