JPS5847823A - Construction of in-place concrete pile - Google Patents

Abstract

PURPOSE:To prevent the lowering of the bonding strength of reinforcing bars caused by mud water films by a method in which soil-cement piles are driven along the periphery side of a pile to be constructed to form a pillar-row sheathing wall, the inside area is excavated, and then fresh water is filled therein. CONSTITUTION:Excavation is made to a given depth while injecting a cement milk mixed with bentonite, etc., from the tip of an earth auger, and then soil- cement piles B are placed orderly in such a way as to overlap them on the periphery of the soil-cement piles B already placed, whereby forming a pillar-row sheathing wall B'. The inside area of the wall B' is excavated by the bucket of an excavator and fresh water D is filled up in the excavated pit C to balance it with earth pressure. Then, an iron bar cage E is inserted, and fresh concrete is gradually poured through a tremie tube F to the bottom of the pit to construct in-place concrete piles.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for constructing cast-in-place concrete piles.

Recently, as buildings become taller, foundation piles are required to have an extremely large bearing capacity, so cast-in-place concrete piles are generally used.

This type of packet earth construction method or reparse circulation construction method uses a muddy water stabilizing solution (hentonite solution or zero
．． M, O) is used, which makes it difficult to mix the muddy water stabilizer and control crosstalk, and the overflowing muddy water causes various pollution problems.

In addition, the hole wall collapses to a greater or lesser degree, and when reinforcing steel is inserted, the hole wall also collapses and the collapsed material mixes into the ready-mixed concrete, making the finished pile brittle. Another drawback was that a muddy water film formed, weakening the adhesion (bond) of the concrete.

This invention aims to eliminate the above-mentioned drawbacks by using fresh water instead of mud stabilizer during excavation.

In this invention, soil cement piles are continuously driven along the outer periphery of the piles to be constructed to construct a column-row earth retaining wall, and then the inside of this earth retaining wall is excavated and removed, and fresh water is poured into the excavated hole. Fill the hole and balance it with the external forces of earth pressure and groundwater pressure applied to the earth retaining wall. When the above excavation reaches a predetermined depth, a reinforcing bar cage is inserted into the hole. Provided is a method for constructing cast-in-place concrete piles in which fresh concrete is gradually poured.

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

First, soil cement piles B are continuously driven along the outer periphery of the piles to be constructed to construct the column retaining wall Bt.

In the case shown in the figure, the construction of the pillar-row earth retaining wall B9 is carried out by using the earth auger 2 of the excavator 1 to drill a cement mixture containing hardening retardant such as bentonite from the ground to the ground from the tip of the earth auger 2. Excavation is carried out while pouring (using the tube axis which is the axis of the auger), and after the excavation reaches a predetermined depth, the soil cement pile B is driven by pulling out the earth auger 2.

Next, the earth auger 2 is positioned on the column advancing direction side of the soil cement pile B, and the peripheral edge of the earth auger 2 is placed over the circumferential surface of the driven soy cement pile B. By sequentially driving the soil seven piles B, a columnar earth retaining wall B1 is formed.

Then, the inside of the columnar earth retaining wall Bl is excavated and removed by the packet 4 of the excavator 3, and the drilled hole C is filled with fresh water to reduce the external force of the soil and groundwater pressure that is received by the columnar earth retaining wall B1. In addition to maintaining a balance with this, collapse of the hole wall of the columnar earth retaining wall B+ is prevented.

When the above-mentioned excavation reaches the supporting layer, a submersible pump is used to suck up the slime at the bottom of the drilled hole C (so that the tip supporting force can be maximized).

After that, a reinforcing bar cage E is inserted into the drilled hole C, and then fresh concrete G is gradually poured from the bottom of the hole using a V-shaped pipe F to create a cast-in-place concrete pile A.

In addition, by pasting a vinyl sheet (not shown) on the hole wall of the column retaining wall B1 before pouring the fresh concrete using the tremor pipe F, the friction effect can be reduced and the ground where the negative chip acts can be reduced. effective.

As described above, according to the method for constructing cast-in-place concrete piles according to the present invention, soil cement piles are continuously driven from the ground to a predetermined depth underground along the outer periphery of the pile to be constructed. After the earth retaining wall has been redone, the inside of this pillar-row earth retaining wall is excavated and removed, and the hole is filled with fresh water. After the hole reaches the specified depth, a reinforcing bar is installed inside the hole. The cast-in-place concrete piles are constructed by inserting the concrete and pouring fresh concrete gradually from the bottom of the hole using a V-shaped pipe, so unlike the conventional muddy water stabilization method, there is no muddy water coating on the surface of the steel rods of the reinforcing bar cage. This eliminates the disadvantages of weakening the adhesion of concrete, making it difficult to mix muddy water and managing crosstalk, and causing various pollution problems due to overflowing muddy water.

In addition, since the column retaining wall is in close contact with the outer periphery of the pile, the column retaining wall becomes the friction surface of the pile9, increasing the friction effect.

Furthermore, since there is a column retaining wall in the ground outside the pile, it is extremely safe even in sandy ground that is prone to quicksand phenomena.

In addition, since the column retaining wall is constructed by continuous driving of soil cement (soil cement) piles, the collapse of the hole wall due to excavation or the collapse of the hole wall when reinforcing bar cages are inserted is avoided.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; Fig. 1 is a side view showing an excavator for making soil-cement piles, Fig. 2 is a cross-sectional plan view of a column retaining wall, and Fig. 3 is a diagram showing an excavator for drilling a hole. Side view, 4th
The figure is an enlarged vertical front view of the columnar retaining wall with holes drilled, Figure 5 is a vertical front view of the same as above with reinforcing bar cages inserted, Figure 6 is a cross-sectional plan view of the same as above, Figures 7 and 8 are tremor pipes. Fig. 9 is a longitudinal sectional front view of the pile with fresh concrete poured into it.

Claims (1)

[Claims] After constructing a pillar-row earth retaining wall by continuously driving mento piles in soi A/- from the ground to a specified depth along the outer periphery of the piles to be constructed, excavate the inside of this pillar-row earth retaining wall. At the same time as removing the soil, the drilled hole is filled with clean water, and after the drilled hole has reached the specified depth, reinforcing bars are inserted into the drilled hole, and ready-mixed concrete is gradually poured into the bottom of the nine holes of the tremor pipe. A method for constructing cast-in-place concrete piles, which is characterized by casting.