JPH07102553A - Precast foundation structure using ground improvement agent - Google Patents

Abstract

PURPOSE:To extend an opportunity to use a precast concrete product as a small scale building foundation by a method wherein an improved ground zone is created by earth produced at a site and a ground improving agent and a precast concrete member in a rectangular shape in cross section having no base is installed thereon. CONSTITUTION:Earth produced at a site and a ground improving agent are well mixed together in a given ratio. Further, compaction is effected to level an upper surface to form an improved ground zone 6. A PC member 1 in the shape of a rectangle in cross section is then installed thereon. The load of an upper structure is applied on a joint and evenly distributed over the bottom of the PC member 1 and transmitted to the central part of the improved ground zone 6. The load is further transmitted to an original ground 4 through the lower part of the improved ground zone 6. The degree of the allowable support force of the original ground 4 making contact with the lower part of the improved ground zone 6 is increased with a press effect of earth being added. This structure copes with a site having an adverse condition and extends an opportunity to use a factory product having excellent term of works.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a structure for using factory-produced products as a basis for small-scale buildings such as houses.

[0002]

2. Description of the Related Art In general, a factory product as a foundation is formed by integrally molding a foundation beam and a foundation board, or by separately molding them and connecting them by some method for use.

[0003]

[Problems to be Solved by the Invention] Concrete molded member manufactured in a factory in advance (hereinafter referred to as PC member)
When using as a building foundation, the ground work such as root cutting, quarry stone, and waste concrete is constructed at the building place in the same way as the in-situ foundation, and the shape of the member is carried in to install and join the PC member. Depending on the size, topography of the construction site, etc., there are restrictions on transportation vehicles, heavy equipment for installation, etc., and opportunities to take advantage of quality, construction period, etc. by using factory products are limited.

The present invention mitigates the drawbacks of such prior art techniques and provides for the advantageous use of PC components.

[0005]

[Means for Solving the Problems] The conventional problems have been solved by providing an improved ground zone with soil generated at the site and a ground improving material, and installing a precast concrete member having a rectangular section without a foundation on it.

FIG. 1 is a sectional view of a substructure according to the present invention. FIG. 2 (a) is a general cross-sectional view of the foundation structure of cast-in-place or precast concrete mill products. FIG. 2B is a sectional view of the rapple concrete foundation structure.

Reference numeral 1 in FIG. 1 is a PC member according to the present invention, and reference numeral 6 in FIG. 1 is obtained by adding and mixing a soil improvement material to soil at the site,
It is a part that has been sufficiently tightened (ie, improved ground zone). The type and amount of ground improvement material to be mixed are determined depending on the type and condition of soil, and the cross section of the improved ground zone is determined according to the load of the upper structure and the bearing capacity of the original ground. It is a basic structure formed by installing a PC member having a rectangular cross section without a foundation plate on the improved ground.

The type and mixing amount of the ground improvement material are described in detail in the Ground Improvement Manual for Cement-Based Solidifying Materials (Cement Association), etc., but they will be confirmed by experiments using soil at the site.

[0009]

[Operation] The load of the upper structure is P of the rectangular cross section without the foundation plate.
It is applied to the column joints of the C member, uniformly distributed on the bottom surface of the PC member, transmitted to the upper center of the improved ground zone, and further transmitted to the original ground from the lower portion of the improved ground zone. The allowable bearing capacity of the original ground contacting the lower part of the improved ground zone increases due to the effect of holding the soil. The improved ground zone should have a necessary and sufficient strength and cross section so that the underlying ground contacting the lower part thereof will not be destroyed by the load of the upper structure. That is, it is not always necessary to use a PC member having a strength such as rapple concrete and a wide foundation board.

[0010]

EXAMPLE FIG. 3 (a) is a diagram in which a cloth foundation subjected to a vertical load of 2 tons per 1 m was mounted on a cohesive ground with an N value of 3. Fig. 3 (a) The improved ground zone of reference numeral 6 is a ground improvement material (registered trademark QCB1 of 250 kg per cubic meter of excavated soil).
00 Kanematsu Nissan Norin) was mixed well, tightened and flattened on the top. The uniaxial compressive strength on the 7th day of the improved ground is 5kg.
/ Square centimeter.

FIG. 4 (a) is a diagram in which a cloth foundation subjected to a load similar to the above is implemented on a sandy ground with an N value of 7. Figure 4
(A) For the improved ground zone of reference numeral 6, 200 kg of ground improvement material per cubic meter of excavated soil (the same as the example in FIG. 3) was used. The uniaxial compressive strength on the 7th day was 12 kg / square centimeter.

FIG. 3 (b) is a diagram of the conventional method under the same conditions as FIG. 3 (a) and FIG. 4 (b). In each case, the building basic structure design guideline (Architectural Institute of Japan) was referred to for calculating the cross section. The scale is the same.

[Table 1]

[Table 2] Table 1 is a comparison table of materials and yield per 1M of length in FIG. 3 and FIG.

[0013]

The PC member of the basic structure according to the present invention has a small cross section because it does not have a basic board. Therefore, it can be easily carried into and installed on site. In other words, it is possible to use a carrying-in vehicle and a heavy equipment for installation with a smaller capacity, that is, it is possible to cope with a site with worse conditions.

Also in the manufacture of PC members in a factory, the cross-section is small and simple, so that the formwork and the equipment are simpler and the manufacturing work itself becomes easier. It requires less material such as concrete and reinforcing bars.

Kuriishi, which is the usual earthwork at the installation site,
No waste concrete is used, so there is no need for material and work. Since a large part of the excavated soil is used at that position, the amount of residual soil that needs to be discharged and disposed can be small.

As described above, the present invention breaks the conventional concept of the basic structure of a small-scale building and expands the opportunity to use factory products excellent in quality and construction period, and at the same time, transmits power to superstructures and PCs.
Providing a foundation structure that is highly compatible with beams, improved ground zones, and original ground.

[Brief description of drawings]

FIG. 1 shows the basic structure of the present invention.

FIG. 2A shows a conventional general foundation structure, and FIG. 2B shows a wrinkle concrete foundation structure.

FIG. 3 is a comparison diagram of the present invention and a conventional structure when installed on a clay ground.

FIG. 4 is a comparison diagram of the present invention and a conventional structure when installed on a sandy ground.

[Explanation of symbols]

 1 PC member 2 Waste concrete 3 Kuriishi 4 Original ground 5 Wraple concrete 6 Improved ground zone

Claims (1)

[Claims] 1. A foundation structure using a soil improvement material for a small-scale building, in which an improved soil zone formed by soil generated at the site and a soil improvement material is provided, and a precast concrete member having a rectangular cross section without a foundation is installed thereon. .