JPH02213522A - Construction method for base of structure - Google Patents

Abstract

PURPOSE:To largely reduce the quantity of improved soil, so as to decrease a cost required for construction and shorten a construction period by partly improving the sandy earth layer below a structure by the provision of a solid wall body and a solid board and restricting fluidity from a side face and an upper face. CONSTITUTION:A solid wall body W circularting the circumference around a position where a structure B is constructed and extending from a ground surface G to a support layer S2 is constructed. Then, the sandy earth layer S1 below the bottom face of the structure B is improved with the suitable thickness of layer throughout its whole surface by means of a solid construction method. A solid board M is constructed continuously on the upper part of the solid wall body W, unified with the solid wall W to form a base F. Then, the sandy earth layers S1 below the structure B is insulated from an outer peripheral part on the side face and the upper face by the wall body W and the solid board M, thereby fluidity being restricted. The earth layer S1 apt to be liquefied may be constructed in such a way that ground water level is lowered or the inside of the wall body W is partitioned by a partition wall to improve a restriction effect and prevent liquefaction.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention is a structure foundation that creates a foundation under a structure that insulates and restrains sandy ground that may liquefy during an earthquake from the surrounding area. It is related to the construction method.

(Problem to be solved by the invention) As a measure to prevent liquefaction of the sandy soil layer that exists under a structure and is likely to liquefy during an earthquake, the weight of the structure has been used as a restraining effect. There are methods to improve the entire soil layer beneath the structure, methods to build piles under the structure and utilize their horizontal resistance and circumferential friction, and methods to build water-stop walls around the structure to block the propagation of water pressure. Methods such as building a structure inside the structure and improving the ground inside it, or allowing the underground part of the structure to reach the supporting layer and completely eliminating the sandy soil layer in that part, etc., are being implemented.

However, since both methods involve improving the entire surface of the ground under the structure, if the thickness of the sandy soil layer or the planar area of the structure's foundation is large, the amount of improved soil or excavation will be enormous, reducing construction costs. The reality is that an increase in construction costs and a prolongation of the construction period are unavoidable.

This invention was made based on this background, and aims to propose a new liquefaction countermeasure that requires a small amount of ground improvement soil.

(Means for Solving the Problems) In the present invention, a solidified wall by ground improvement, which is a water stop wall that blocks the propagation of water pressure, is constructed only around the structure construction location, and the sandy soil directly under the structure is By improving the upper layer horizontally to the required thickness and creating a consolidated slab, the amount of improvement of the sandy soil layer can be significantly reduced, reducing construction costs and shortening the construction period.

The sandy soil layer is insulated from its surroundings by the consolidation slab under the structure and the surrounding consolidation walls, and its behavior during an earthquake is restrained, thereby suppressing the occurrence of liquefaction. Also, during a major earthquake,
Even if liquefaction occurs, the liquefaction layer directly under the building is blocked by the solidified slab and surrounding solidified walls, so the supporting function of the building is maintained.

Consolidated walls are constructed by improving the ground around the structure construction location vertically from the ground surface to the supporting layer below the sandy soil layer, which goes around the structure in the form of an underground continuous wall. A continuous pine slab is built on top of this solidified wall,
Isolate the entire sandy soil layer under the structure from the surrounding area.

(Example) The present invention will be explained below based on the drawings showing one embodiment.

As shown in Fig. 1, this invention
The surrounding sandy soil layer is improved throughout the entire layer by ground improvement.
This is a method of constructing a foundation F that is isolated from 1 and restrains its behavior during an earthquake.

As shown in the figure, the foundation F goes around the structure B and is made up of a solidified wall W that reaches from the ground surface G to the support layer S2 and a solidified slab M that is constructed horizontally just below the structure B. It is constructed by improving the ground using the injection method or the consolidation method that creates consolidated columns by mixing and stirring.

The solidified wall W goes around the construction position of the structure B and is constructed over the entire sandy soil layer Sl from the ground surface G to the support layer S2.

When the underground part of the structure B is constructed underground, after the solidification wall W is constructed, root cutting work can be performed using this as a retaining wall.

Consolidation plate M covers the entire sandy upper layer S1 under the bottom of structure B, improves the ground with an appropriate layer thickness using the consolidation method described above, and is constructed continuously on the top of consolidation wall W, and is consolidated. It is integrated with the wall W.

As a result, the sandy soil layer SI under the structure B is insulated from the outer periphery on the side and upper surfaces by the consolidation wall W and the consolidation plate M, and the flow is restrained.

Figure 1 shows an example in the case of a direct foundation, and Figure 2 shows an example in the case of a pile foundation. In the figure, P indicates anti.

In addition, if there is a high possibility of liquefaction of the sandy soil layer S, the third
As shown in the figure, the groundwater in the sandy soil layer S1 can be drained by sand compaction, deep wells, etc. to lower the groundwater level, or as shown in Figure 4, the inside of the consolidation wall W can be partitioned off with partition walls W. , the effect of preventing liquefaction is enhanced by increasing the restraining effect of sandy soil N s + .

(Effects of the Invention) This invention is as described above, and since the sandy soil layer under the structure is partially improved and restrained from the sides and top, the amount of improved soil can be greatly reduced, and the construction This will reduce costs and shorten the construction period.

[Brief explanation of the drawing]

Figures 1-1 and II are an elevation view and a plan view showing an embodiment of the present invention, Figure 2 is an elevation view showing another embodiment, and Figure 3 is a drainage situation of a sandy soil layer. Elevation view showing Figure 4-I
, II is an elevational view and a plan view showing an embodiment in which partition walls are provided, and FIG. 5 is an elevational view showing another embodiment. B...Structure, F...Foundation, W...
... Consolidated wall, M... Consolidated plate, W...
・Partition wall, S,, S, “...Sandy soil layer, S2
...Supporting layer, G...Ground surface, P...
...Pile. Part ■

Claims (1)

[Claims] 1) Improve the ground around the structure construction location in the vertical direction from the ground surface to the support layer below the sandy soil layer, and create a continuous solidified wall that goes around the structure in the form of an underground continuous wall. At the same time, the sandy soil layer directly under the structure was similarly ground-improved in the horizontal direction, and a mat slab-like consolidation slab with the required thickness was created continuously on the top of the consolidation wall, and the area under the structure was improved. A method for constructing a structure's foundation, which consists of constructing a foundation that is insulated from the surrounding area through all layers of sandy soil.