JPH10183642A - Method for constructing structure foundation in viscous soil ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve construction feasibility by a method wherein after improved soil is banked on a viscous soil ground, a foundation pile is made to penetrate to a load bearing layer, and a floor slab having a floor steel plate forming permanent forms is formed on pile heads. SOLUTION: Improved soil 5 comprising a cement curing material and soil is cured as a bank on a viscous soil ground 1 of a present ground 11 and a given strength is provided. A foundation pile 3 is then driven down to penetrate through an underlying load bearing layer 2 and a capital made of precast reinforced concrete is arranged such that a central hole is fitted in a pile head. Floor steel plates forming permanent forms are laid on a frame assembled on modified soil 5 between the capitals. After reinforcing bars are arranged on the floor plates, floor slab concrete 4 is placed, a gap between a pile 3 and the capital is filled with mortar, and the concrete 4 and the capital are integrally formed by means of reinforcing bars. This method remarkably reduces a banking amount and a viscous soil ground subsidence, and uses piles of property quality, and further improves workability of a flat slab construction method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of constructing a foundation for constructing a building on a viscous ground such as a former rice paddy field.

[0002]

2. Description of the Related Art When constructing a building on a viscous ground 1 such as a site of a paddy field as a site, prior to the construction work, the ground 11 is raised to a planned ground 12 with a buried land 13. Construction is performed. The cohesive ground is normally in a normal consolidation state (a state in which the effective stress of the cohesive soil is equal to the consolidation yield stress), and the cohesive soil is not deformed as it is, but the load of the embedded soil 13 is loaded on the ground. When the effective stress increases, the water in the viscous soil is discharged and deformed, causing land subsidence due to consolidation.
(See FIG. 4).

As a countermeasure against land subsidence due to this consolidation, the following two methods are usually adopted.

(1) When there is enough time.

[0005] A large amount of embankment 15 is loaded on the buried land 13 to promote the settlement of the viscous ground 1 by its weight,
When it is considered that the subsidence has sufficiently proceeded, a large amount of the embankment 15 is removed, and the ground preparation work is performed again. (See FIG. 5).

(2) When there is not enough time.

[0007] Give up the support of the building by viscous ground 1,
After the ground preparation work, the foundation pile 3 is driven into the support layer 2 below the viscous ground 1 and the entire building is supported via the foundation pile 3.
And the land subsidence of the viscous ground 1 is left to occur. (See Fig. 6)

[0008]

According to the above-mentioned method (1), in addition to the ground preparation work, the work of loading and removing a large amount of embankment is added, so that the construction period becomes longer and the construction cost increases. A particularly big challenge is that it takes a long time per year to determine that land subsidence is complete.

In the above method (2), after the pile is driven into the ground, land subsidence occurs due to the weight of the loaded soil, and the land subsidence acts not only as a negative frictional force on the foundation pile but also as a gap 16 at the pile head. And lower the bearing capacity of the foundation pile. For this reason, it is necessary to use foundation piles of excessive quality in anticipation of a decrease in bearing capacity.

[0010]

SUMMARY OF THE INVENTION The present invention uses a foundation pile of appropriate quality in the case where there is not enough time in the above (2), and facilitates the operation of a construction vehicle, thereby shortening the construction period and reducing the construction work. It is intended to provide a construction method for efficiently building a foundation at a low cost.

That is, the present invention provides (A) a step of embedding improved soil, which is a mixture of a cement-based solidifying material and soil, on a cohesive ground to improve the surface layer of the cohesive ground; After the solidification, the pile tip penetrates into the lower support layer and the foundation pile is driven so that the pile head projects above the improved soil layer. (C) Precast reinforced concrete capital is fitted to the protruding foundation pile pile head. And laying the floor steel sheet between adjacent capitals, (D) the floor steel sheet as a form,
A method for constructing a floor slab by casting reinforced concrete thereon, and a method for constructing a foundation for a building on a viscous ground.

A first point of the present invention is to improve the surface layer of a cohesive ground by using an improved soil which is a mixture of a cement-based solidifying material and soil as an embankment for raising the level, and to improve a planned ground level above the ground. First, the floor slab is constructed by the flat slab method, and the constructed floor slab is used as the planned ground.
The amount of improved soil to be embanked should be as small as possible without impeding the operation of construction vehicles running on it.
It is preferable from the viewpoint of suppressing land subsidence, and is usually embanked to a thickness of about several tens of cm. The amount of embankment is significantly less than the conventional embankment for raising, and the amount of embankment is greatly reduced.

A second point of the present invention is that, in the above flat slab method, a precast reinforced concrete product is used as capital for a foundation pile head, and a floor steel plate is discarded as a post-cast reinforced concrete form for constructing a floor slab. The point of use is to integrate the floor slab and the foundation pile via capital with good workability.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is an elevational sectional view of one example of a foundation constructed according to the present invention, FIG. 2 shows an example of installation of a precast reinforced concrete capital, (a) is a plan view of a square capital, and (b) is A vertical sectional view of a state in which square capital is installed and floor slab concrete is cast, (c) is a plan view of a round capital, and (d) is a state in which round capital is installed and floor slab concrete is cast. FIG. 3 shows an example of arrangement of floor steel plates at the time of placing floor slab concrete, (a) is a plan view, and (b) is BB of (a).
FIG. 2C is a view as viewed from the direction of the arrow, and FIG.

The construction procedure of the present invention will be described with reference to FIGS.

(1) An improved soil 5 which is a mixture of a cement-based solidifying material and soil is tens of cm on the viscous ground 1 of the local ground 11.
Fill and cure to a thickness of 5mm and wait for the improved soil 5 to harden.

(2) When the improved soil 5 hardens and develops a predetermined strength, it becomes possible for a construction vehicle to ride on it, and at the same time, the ground rigidity of the pile head of the foundation pile 3 to be driven next is reduced. Get higher. A construction vehicle is loaded on the improved soil 5,
The foundation pile 3 is driven in until its tip penetrates into the lower support layer 2. The pile head of the foundation pile 3 is projected about several tens of cm above the improved soil 5.

(3) The precast reinforced concrete capital 6 is installed by fitting the center hole of the precast reinforced concrete capital 6 into the pile head of the foundation pile 3.

(4) L on the improved soil 5 between the capitals 6
A gantry is assembled from the shape steel 9, and a floor steel plate 8 serving as a disposal form is laid on the gantry. As the floor steel plate 8, a normal deck plate or keystone plate is used.

(5) Predetermined reinforcement for the floor slab is provided on the floor steel plate 8 and the floor slab concrete 4 is poured. The gap between the pile head of the foundation pile 3 and the hole of the precast reinforced concrete capital 6 is filled with concrete or mortar. The floor slab concrete 4 and the capital 6 are integrated by a connecting reinforcing bar 7 protruding from the capital 6, and the capital 6 and the foundation pile 3 are integrated by the filled concrete or mortar. Floor slab concrete 4
After the hardening of the soil, the construction of the foundation on the viscous ground 1 is completed.

The upper surface of the constructed floor slab concrete 4 becomes the planned ground 12, and the local ground 11 is raised to a predetermined height. At the same time, a space having a height corresponding to the raised height is formed between the lower surface of the floor slab concrete 4 and the upper surface of the improved soil 5.

[0023]

【The invention's effect】

(1) It is possible to greatly reduce the amount of buried soil by using improved soil mixed with cement-based solidification material as buried soil for raising the soil, and to significantly reduce the land subsidence of the cohesive ground that is in a normally consolidated state. Can be reduced. As a result, foundation piles, which had to be used in the past and had to use excessive quality in anticipation of the effects of land subsidence, can be replaced with original proper quality piles, and costs can be reduced.

(2) The workability of the flat slab method can be improved by using a precast reinforced concrete product as the capital of the foundation pile head and using the floor steel plate as the formwork of the post-cast reinforced concrete for constructing the floor slab. improves.

In summary, a reasonable basis is provided in all aspects of construction period, cost and quality.

[Brief description of the drawings]

FIG. 1 is a sectional elevation view of an example of a foundation constructed according to the present invention.

FIG. 2 shows an example of installation of precast reinforced concrete capital, (a) is a plan view of square capital,
(B) is a vertical sectional view in a state where square capital is installed and floor slab concrete is cast, (c) is a plan view of round capital, and (d) is a round capital is installed and floor slab concrete is installed. It is an elevation sectional view in the state where it was cast.

3A and 3B show an example of the arrangement of floor steel plates at the time of placing floor slab concrete, wherein FIG. 3A is a plan view, FIG. 3B is a view taken along the line BB of FIG. 3A, and FIG. It is a CC arrow view.

FIG. 4 is a conceptual sectional view of a ground preparation work for raising a local ground to a planned ground by burying soil.

FIG. 5 is a conceptual elevation sectional view of a method for improving the ground by promoting consolidation by loading a large amount of embankment.

FIG. 6 is a conceptual vertical sectional view of a conventional pile foundation method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... viscous ground, 2 ... support layer, 3 ... foundation pile, 4 ... floor slab concrete, 5 ... improved soil, 6 ... precast reinforced concrete capital, 7 ... connecting rebar, 8 ... floor steel plate,
9: L-shaped steel, 11: local soil, 12: planned ground, 13: buried, 14: local soil after sinking, 15: embankment, 16: clearance of pile head.

Claims (1)

[Claims] (A) a step of embedding an improved soil, which is a mixture of a cement-based solidifying material and soil, on a cohesive ground to improve the surface layer of the cohesive ground; and (B) a pile after solidification of the improved soil. Driving the foundation pile so that the tip penetrates the lower support layer and the pile head protrudes above the improved soil layer. (C) Fit the precast reinforced concrete capital to the protruding foundation pile head and install it. A step of laying a floor steel sheet between adjacent capitals, and (D) a step of constructing a floor slab by disposing of the floor steel sheet as a formwork and placing reinforced concrete thereon. How to build a building foundation into a building.