JPH03103535A - Countermeasure structure for liquefaction of building - Google Patents

Abstract

PURPOSE:To control a liquefied phenomenon and to stabilize the subsoil by loading a soil cement layer to the outside of an underground wall consisting of steel pipes driven up to a hard bed in the subsoil around a building and, at the same time, filling the insides of the steel pipes with cement. CONSTITUTION:Steel pipes 8 are driven in succession up to a hard bed 4 in the subsoil 1 around a building 5 to be constructed, and an underground wall 7 used as a retaining wall is provided. After that, a soil cement layer 10 is loaded to the outside of the underground wall 7 and, at the same time, the inside of each steel pipe 18 is filled with soil cement 11. Then, a circumferential wall 14 of the building 5 constructed on the foundation piles 6 and the upper parts of the steel pipes 8 are held together as a unit through studs 14. The subsoil of the building 5 is separated from an outside liquefaction dangerous layer 3 through the underground wall 7, and the shearing deformation in the inside subsoil is prevented. According to the constitution, the constructed subsoil can be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a structure for preventing limbs of buildings in ground areas where there is a risk of liquefaction due to earthquakes.

(Prior Art) Generally, it is known that in sandy ground containing a lot of water, when an external force due to an earthquake is applied, the ground becomes liquid-like, a so-called liquefaction phenomenon. This phenomenon occurs when the pore water pressure of the sandy ground rapidly increases due to local shear deformation of the sandy ground, creating water currents that cause sand particles to flow.

Conventionally, countermeasures against ground liquefaction include compaction methods such as sand compaction, mixed treatment methods that incorporate cement or soil solidifying agents, replacement methods that replace soil with soil that is less likely to form limbs, and the use of crushed stone in the ground. Drainage construction methods that install a large number of pillars are known, but not only do they require large-scale construction, but they are often subject to restrictions on the construction site.

Therefore, as a construction method different from the above, a construction method in which a porous sea bream pipe filled with crushed stone etc. is used as the foundation pile of the building, and the excess water pressure is released upward through the pile.
Construction methods have been proposed in which porous walls are buried in the ground around buildings to dissipate excess pore water pressure.

(Problem to be Solved by the Invention) However, the former type of perforated steel pipe piles not only has problems with the strength of the pile, but also has many holes that cause lateral flow, resulting in excessive gaps. There is a problem that water pressure is not sufficiently dissipated. Furthermore, even in the case where the porous wall is buried, excess pore water pressure cannot be sufficiently dissipated. Moreover, although these construction methods have some effect in releasing excess pore water pressure upward, they are not sufficient to suppress the lateral movement of the ground that occurs during an earthquake.

Furthermore, in areas where there is a risk of liquefaction, the bearing capacity of the ground itself is weak, so special measures to increase the bearing capacity are required, such as requiring longer foundation piles or increasing the number of foundation piles. However, the construction cost was troublesome and required a large amount of money.

In view of the above-mentioned conventional problems, the present invention utilizes an underground wall installed as earth retaining for construction of the basement of a building, and connects the wall and the building integrally to the building construction ground. The aim is to suppress the spread of liquefaction caused by earthquakes, and to create structures with high earthquake resistance and supporting capacity.

(Means for Solving the Problems) The structure of the present invention for achieving the above object will be described with reference to embodiments and corresponding drawings.
Steel pipes 8.8 are continuously connected in the ground surrounding the building 5 to be constructed, a fill cement layer IO is applied on the outside, and each steel pipe 8 is filled with fill cement l1. The structure is characterized in that a wall 7 is installed, a structure 5 is constructed inscribed in this underground wall 7, and the upper part of the underground wall 7 and the structure 5 are integrally connected.

(Function) The present invention is configured as described above, and the constructed ground of the building 5 is separated from the outside ground by the underground wall 7. Therefore, the influence of excessive pore water pressure from the outer ground caused by an earthquake is suppressed, and the lateral flow of the ground is suppressed, and shear deformation of the inner ground of the underground wall 7 is prevented.

The underground wall 7 is formed by integrally connecting steel pipes, and a fill cement layer 10 is applied around the steel pipes, and soil cement II is also filled in each sea bream pipe, so it is made strong and strong enough to withstand construction. It will provide great support. In addition, since the underground wall is a heavy structure, it is also used as a restraining force against the floating of the building when liquefaction occurs.

(Point Embodiment) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In Figures 1 and 2, ■ indicates the ground that is at risk of liquefaction due to an earthquake, and generally a soft liquefaction risk layer (saturated layer) 3 is formed under the topsoil layer 2 over a considerable depth. , and below that is hard stratum 3.

5 is a structure built on the above-mentioned ground l, with hard ground layer 4
It is supported by a foundation shaft 6.6 that is deeply rooted and sunk inside. 7 is an underground wall formed around this building 5, which is a combination of continuous steel pipes and soil cement;
As shown in Figs. 3 and 4, a large number of steel pipes 8.8 are sunk into the ground I so that their lower parts are rooted in the hard stratum 4 below the liquefaction danger layer 3. They are connected by joints 9, 9, and a soil cement layer IO is applied to the outside thereof, and each steel pipe 8 is also filled with filling soil cement 11. In this case, if the steel pipe 8 is a striped steel pipe with a large number of protrusions 12 threaded around its outer periphery, the bond between the steel pipe 8 and the soil cement 10 will be strengthened.

Further, on the upper part of each steel pipe 8, on the side in contact with the peripheral wall l3 of the building 5, a stud 14, 14 is provided to protrude and be buried in the concrete of the peripheral wall l3 as a connector with the peripheral wall l2. As shown in FIG. 3, this stud 14.14 is attached to a triangular stud plate l5 fixed to the steel pipe 8.
It will be installed in the field by arc stud welding and will project diagonally upward and downward.

The underground wall 7 is installed prior to the construction of the structure 5, but at that time, the fill cement layer IO is not applied to the upper inner side of the underground wall 7 in contact with the surrounding wall l3, and the steel pipes 8.8 are installed on the surrounding wall. Make it directly contact l3. After constructing the underground wall 7, the ground inside it is excavated, foundation piles 6, 6 are sunk, and the structure 5 is constructed on top of the foundation piles 6, 6. Building 5 is the surrounding wall I3 of the underground part.
are in contact with the steel pipes 8.8 of the underground wall 7, and studs 14.14 protruding from each steel pipe 8 are buried in the poured concrete, so that the upper part of the underground wall 7 and the underground part of the structure 5 are integrated. This results in a rigid connection.

(Effects of the Invention) As explained above, the present invention connects the JT continuously in the ground surrounding the building to be constructed, coats the fill cement layer on the outside, and We installed an underground wall filled with fill cement, built a building inscribed in this underground wall, and integrated the upper part of the underground wall with the building. It has many excellent effects such as:

(]) The underground wall built around the tUt structure divides and isolates the strata at risk of liquefaction inside and outside the building, and the ground inside the underground wall is separated from the ground outside. It is possible to suppress the effects of shear strain on the liquefaction-prone ground and excessive pore water pressure during an earthquake, and it is possible to stabilize the ground on which buildings are built.

(2) Since underground walls are made of steel pipes covered with soil cement to make them strong, they have a large resistance against lateral movement of the ground, and they also have a strong resistance to the lateral movement of the ground. It will exhibit a large bearing capacity, and the load on the bearing capacity of the foundation piles can be greatly reduced. In addition, since it has a heavy structure with steel pipes and fill cement on the underground wall, and is firmly installed in the ground, it will exhibit great resistance against buoyancy that occurs when liquefaction occurs.

(3) The earth retaining facilities required when constructing a building are no longer necessary, and costs can be reduced accordingly.

[Brief explanation of drawings]

Fig. I is a vertical sectional view showing one embodiment of the present invention, Fig. 2 is a cross-sectional view of the same, Fig. 3 is an enlarged longitudinal sectional view showing the state of connection between the steel pipe and the building, and Fig. 4 is a vertical sectional view showing the connection state between the steel pipe and the building. FIG. 3 is an enlarged plan cross-sectional view showing a main part of the inner wall. ■...Ground 2...Topsoil layer 3...Liquefaction risk layer 4...Hard soil layer 5...Building 6...Foundation pile 7...Underground wall 8...Steel pipe
10, I1... Fill cement l3... Peripheral wall
14...Stud figure 1

Claims (1)

[Claims] Steel pipes are connected continuously into the ground surrounding the building to be constructed, a layer of soil cement is applied to the outside of the pipes, and an underground wall filled with soil cement is installed inside each steel pipe. A liquefaction-resistant structure for a building, characterized by building the building inscribed in the middle wall and integrally connecting the upper part of the underground wall and the building.