JPS5824024A - Backfilling work for empty portion of in-place pile - Google Patents

Abstract

PURPOSE:To ensure the passive earth pressure of soil and sand backfilling in the empty portion of in-place pile by a method in which a curable mud water is charged into the empty portion and then backfilling material, e.g., excavated soil, etc., is packed in the empty portion. CONSTITUTION:A curable mud water 3 composed of about 5-10% bentonite and about 10-20% a hardening agent, e.g., ordinary or slag cement, etc., is charged into the impty portion 2 from the upper end to the ground of an in-place pile, and then a backfilling material 4, e.g., excavated soil, etc., is packed into the empty portion to the ground level. In the empty portion 2 filled with the solidified mixture of the curable mud water 3 and the embedding material 4, sufficient passive earth pressure can be expected because no deformation and settlement occur in the peripheral area of the pile 1 owing to its higher strength than the surrounding ground.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for backfilling the blank portion of a cast-in-place pile.

When building a structure that includes an underground section on ground where a thick layer of soft soil has accumulated, it is common to support the structure by driving piles that reach the support layer.

When using cast-in-place piles that are constructed from the ground, the poured concrete is stopped near the bottom of the structure's foundation. The area from the bottom to the top of the foundation where no concrete was poured, that is, the blank area, was backfilled with earth and sand.

However, the backfill earth and sand could not be sufficiently compacted and was disturbed and extremely loose, so its strength was significantly lower than that of the surrounding ground, and it was not possible to expect a passive earth shoal. Therefore, if there is a large proportion of areas that are not backfilled, retaining walls constructed prior to cast-in-place pile construction may
Before excavation work began, there were many problems such as deformation.

SUMMARY OF THE INVENTION In order to eliminate the above-mentioned drawbacks, it is an object of the present invention to allow passive soil to be incorporated into the earth and sand backfilled into the blank part of a cast-in-place pile.

Embodiments of the present invention will be described below with reference to the drawings.

1 is a cast-in-place pile made by pouring concrete into a hole drilled with a suitable excavator such as an earth drill. The cast-in-place pile/dry part from the upper end to the ground surface is first coated with bentonite s to θ% and a hardening agent such as ordinary cement or blast furnace cement. A predetermined amount of hardening mud 3 consisting of 20% is poured from the upper part of the keratin, and then reclamation material such as excavated soil is thrown in from the upper part and backfilled to the ground level. Then, the gaps in the backfill material such as excavated soil are filled with hardening mud 3, and over time, the harden mud 3 in the blank space and the backfill material solidify as one. do.

Alternatively, the hardening mud 3 and the backfilling material may be stirred and mixed in advance on the ground and then charged into the blank part.

The following table shows the unconfined compressive strength of the solidified material when backfilling material is mixed with hardening mud. According to this, the solidified material shows a strength of lυ in the age of 3 weeks (2 g days), and the surrounding ground (03 to
It was confirmed that the strength was greater than Zθ, and that it was able to fully accommodate the passive tosho.

If this is not available, it is also a hot idea to fill and solidify the entire dry-shot area with hardening mud, or to mix a hardening agent into the drilling mud in the dry-shot area to convert it into hardenable mud and solidify it. It is possible.

The method of backfilling the blank portion of cast-in-place piles according to the present invention is as follows:
When the pile is constructed using the above process, the hollow cast part, which is made of a solidified mixture of hardening mud and backfill materials such as excavated soil, has stronger strength than the surrounding ground and deforms into the ground around the pile.・
Since there is no subsidence, passive earth pressure can be fully accommodated, and the mixed solidity has low strength, so underground excavation work can be carried out smoothly without folding after the pile work is completed. It also has the advantage of allowing progress.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a method of backfilling the blank portion of a cast-in-place pile according to the present invention.

Claims (1)

[Claims] A method for backfilling the hollow part of a cast-in-place pile, characterized by pouring hardening mud into the hollow part of the cast-in-place pile, and then backfilling with backfilling material such as excavated soil.