GB2192419A

GB2192419A - Method of producing a pile or a diaphragm wall

Info

Publication number: GB2192419A
Application number: GB08616799A
Authority: GB
Inventors: Juei-Jse Lin
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-07-10
Filing date: 1986-07-10
Publication date: 1988-01-13
Also published as: GB8616799D0

Abstract

A pile shoe (2) or a diaphragm wall footing fixed to the bottom of a reinforcing cage (1), and having a grouting pipe (3) and a displacing pipe (4) extending therethrough is placed into a bore (5). Water under pressure is then made to flow through the grouting pipe (3) to flush loose soil below the pile shoe (2) and to form slurry (51) which is then discharged to the ground level through the displacing pipe (4). Concrete (81) is then grouted into the reinforcing cage (1) and allowed to set, whereafter grout (52) and/or soil stabilizing agent is forced into the space around and below the pile shoe (2) or diaphragm wall footing to stabilize and strengthen the foundation. The cage (10) may be encased by a waterproof membrane (21) to prevent ingress of slurry (51). <IMAGE>

Description

SPECIFICATION Slurry displacement and soil stabilization method for pile foundation This invention relates to construction of castin-place concrete pile or diaphragm wall, particularly a method to flush and displace soil at the bottom of file foundation, and to fill grout and soil stabilizing agent after concrete grouting and setting of concrete in order to stabilize pile foundation.

Generally, foundation engineering is a key to support a building firmly. Conventionally, pile or diaphragm wall is constructed directly, a considerable quantity of slurry may accumulate in the bottom of pile bore or well, and it can't be displaced completely after grouting for making cast-in-piace concrete pile. The soil for support the pile is always loosen during boring process. Therefore stabilization of pile foundation is always not satisfactorily.

Conventionally, slurry in the bottom of pile bore or well is pumped out directly or displaced by concrete grouted to the bottom directly. However, dense slurry and loose soil at the bottom can't be removed by the conventionaly method, and then, pile foundation or diaphragm wall does not stand on satisfactorily stabilized ground, sinking may occur and safety of construction works is affected.

The present invention relates to a slurry displacement and soil stabilization method for pile foundation applicable to cast-in-place pile and diaphragm wall construction. It uses a pile shoe or a diaphragm wall footing fixed to the bottom of a reinaforcing cage, grouting pipe and displacing pipe penetration into the pile shoe or footing located in the bottom of a bored well, and high pressure water to flush soil below the pile shoe or footing to form slurry which is then discharged to ground level through the-ldisplacing pipe before grouting of concrete. After setting of the concrete, grout and/or soil stabilizing agent are filled to space around and below the pile shoe to stabilize the ground in order to increase loading capacity of the pile foundation or diaphragm wall, and to prevent from sinking.

Therefore, the main objective of the present invention isto provide an effective method for slurry displacement and soil stabilization which displace slurry and loss in the bottom of bored well both in the middle and corners of the well.

Another objective of the present invention is tb stabilize ground, increase loading capacity and prevent from sinking by filling grout and soil stabilizing agent after grouting.

Embodiments-of the invention are described by way of example, with reference to the drawings, in which: Figure 1 is a sectional view illustrating application ofthe present invention In a bored well, the first embodiment according to the present invention; Figure 2 illustrates connection of the grouting pipe and displacing pipe to the pile shoe in the first embodiment; Figure 3 is a sectional view illustration application of the present invention with a pipe for both grouting and displacing for pile shoe of different pile shoe, the second embodiment according to the present invention, in which the manifolds are shown in perspective view; Figure 4 illustrates the third embodiment according to the present invention; Figure 5 is a sectional view illustrating working with the first embodiment according to the present invention; and Figure 6 is a sectional view illustrating result of application of the first embodiment in a bored well.

Please refer to Figure 1, a sectional view of application of an embodiment in a bored well according to the present invention. The present invention involves Fixing of a pile shoe (2) to the-bottom of a reinforcing cage (1).

The pile shoe (2) can be a concrete structure precasted at the bottom of the reinforcing cage (1). During the precasting process, the lower manifold (32) of a grouting pipe (3) and the lower manifold (42) of a displacing pipe (4) are pre-installed within the pile shoe (2) so that the grouting pipe (3) and the displacing pipe (4) can penetrate into the pile shoe and connect to each other through some holes at the bottom of the pile shoe as shown in Figure 2. The manifolds of both the grouting and displacing pipes are distributed evenly at the bottom of the pile shoe in order to extend grouting and displacing effect.

After placing the reinforcing cage (1) with the pile shoe (2) into a bored well (5) till the pile shoe (2) has its bottom kept in touch with the ground (52), water can be filled into the ground (52) via the main pipe (31) and manifold (32) of the grouting pipe (3) and displaced to ground level through the manifold (42) and main pipe (41) of the displacing pipe (4).

In order to prevent from the flowing of slurry (51) into the reinforcing cage (1) above the pile shoe (2) through the gap between the pile shoe (2) and the bored well (5) which may affect further grouting, the reinforcing cage (1) above the pile shoe (2) are covered with water proof membrane- (21) made of PE film or other water proof material (see Figure 2).

Please refer to Figure 3, a sectional view of application of another embodiment in a bored well according to the present invention. It is different from that shown at Figure 2 in the shape of the pile shoe (2) and the way to contact with the ground, and it is an alternative choice to meet different soil condition and bore size.

In the latter embodiment, a single pipe (6) for grouting and displacing is used instead of the aforesaid grouting pipe (3) and displacing pipe (4). The pipe (6) has a main pipe (61) and a manifold (62) penetrating the pile shoe (2). During operation, water grouting and slurry displacement are done alternately.

Please refer to Figure 4, which illustrates the third embodiment according to the present invention to fist application of construction of diaphragm wall. It is different from that shown at Figure 2 in the shape of bored well (7) reinforcing cage (1) and footing (2') for the diaphragm wall. The manifold (42) of the dis placing pipe (4) and the- manifold (32) of the grouting pipe (3) are distributed widely in the footing (2'), and number of main pipes (41 and 31) for the displacing pipe (4) and grout ing pipe (3) can be increased if necessary.

Waterproof membrance is installed above the footing (2'). Please refer to Figure 5, a sec tional view illustrating working with the first embodiment. The grouting pipe (3) is connect ing- a water-source so that water which flows through the' main pipe (31), the manifold (32) and the pipe shoe (2) is used to flush loose soil on the ground (52) below the pile shoe (2) in order to form slurry-,(51), which is then discharged via the- manifold (42) at- the bottom of the pile shoe (2) and the main pipe (41) to the ground level. Finally, concrete (81) is grouted through a grouting pipe (8) into the reinforcing cage (1) above the pile shoe (2) till the pile shoe gets contact with a predeter mined rigid ground level. Grout and/or stabiliz ing agent are filled by pressure grouting to the space (9) around and below the pile shoe (2) to improve soil condition (see Fig. 6) in order to strengthen loading capacity of the pile and to prevent from sinking.

For construction of diaphragm wall, the same process of flushing slurry -displacement, grouting 'and soil improvement is applicable to meet the'thigh loading capacity as required by diaphragm wall and to prevent from sinking.

Claims

1. A slurry displacement and. soil stabiliza tion method for pile foundation by using of a pile shoe or a diaphragm wall footing fixed to the bottom of a reinforcing cage, a grouting pipe and- a displacing pipe penetrating into the pile shoe or diaphragm wall footing placed in a bored -well and water-to flush loose soil in the bottom of the bored well' through the grouting pipe and displacing fipe to form slurry which is then discharged to ground level through the displacing pipe before concrete is grouted into the reinforcing cage above the pile shoe; and filling of-grout and soil stabiliz ing agent to space around and below the pile shoe after setting of concrete in order to strengthen the foundation to increase loading capacity and to prevent from sinking

2.A slurry displacement and soil stabiliza tion method for pile foundation as claimed in Claim 1 wherein a plurality of manifolds are distributed evenly at the bottom of the pile shoe or diaphragm wall footing, a half of the manifolds are connecting to a grouting pipe, and another half of the manifolds are connecting to a displacing pipe in order to increase contact of the grouting pipe and the displacing pipe to the ground for improving grouting and displacing effect.

3. A slurry displacement and soil stabilization method for pile foundation as claimed in C!aim 1 wherein a plurality of manifolds -are distributed evenly at the bottom of the pile shoe or diaphragm wall footing and the manifolds are connecting to a pipe for grouting and displacing alternately.

4. A slurry displacement and soil stabiltzation method for pile foundation as claimed in Claim 1 wherein the reinforcing cage above the pile shoe is covered with waterproof membrane to prevent from flow of slurry into the reinforcing cage through the gap between the pile shoe and the reinforcing cage.