RU2260653C1 - Method for bored and cast-in-place pile forming in ground having silty interlayers - Google Patents

Abstract

FIELD: building, particularly to erect foundations of artificial structures.

SUBSTANCE: method involves drilling hole in ground; arranging casing pipe in the hole; determining the levels of silty interlayer locations; immersing reinforcement case with retained form in hole, wherein retained form is made as geotextile shell and connected to reinforcement case at silty interlayer location zone. Shell has height H, which is equal to sum of at least two reinforcement case diameters and silty interlayer thickness and exceeds above zone ends for at least pile diameter value.

EFFECT: extended range of cast-in-place pile erection methods with the use of removable casing pipes, increased quality and reliability of pile building is silty ground or in ground with silty, namely sapropel, interlayers.

6 cl, 3 dwg

Description

The invention relates to the field of construction, namely to the production of foundation work carried out in the construction of artificial structures. The foundations of deep laying, built in a wide variety of soils using both domestic and imported equipment, have become widespread. This is due to their high technical and economic advantages (large bearing capacity, profitability, high mechanization of work) over other types of foundations. Bored piles can be built both in hard, dense rocks, and in sufficiently weak, underlain by strong rocks.

The closest known method is the method of constructing a bored pile in a structure for securing a slope in non-rocky soils, in which, after a well is formed, a reinforcing cage is placed in it and the well is filled with concrete, and drainage elements in the form of panels of non-woven synthetic material are used to drain ground water ( SU No. 878862, 1981).

The construction of bored piles in monogrunts is well mastered and is not difficult. It is also not difficult to construct bored piles in soils with alternating layers with different bearing capacity and physical and technical properties. Problems begin when it is necessary to build bored piles in silty soils underlain by solid rocks or in soils with silty interlayers (sapropels). In these cases, as a rule, it is necessary either to abandon the use of bored piles and switch to driven piles, or to perform bored piles in abandoned steel pipes or reinforced concrete shells, since concreting piles using the VPT (vertically moving pipe) method in silt soils can be done when removing casing pipes lead to a loss in the quality of the bored pile due to the mixing of cast concrete and sludge (sapropel). The use of non-removable steel pipes or reinforced concrete shells instead of removable casing pipes causes additional technological operations that extend the time of work, and also significantly increases the cost of building foundations.

The objectives of this technical solution are to expand the scope of classical methods for constructing bored piles using removable casing pipes, to ensure the guaranteed quality and reliability of bored piles when building them in completely silty soils or in soils with silty interlayers (sapropels).

This is achieved by the fact that the method of constructing a bored pile in the soil with silty interlayers includes forming a well in the soil with a casing in it, determining the level of silt interlayers in the well, immersing the reinforcing cage in the well with a fixed formwork in the form of a geotextile sheath fixed to in the zone or in zones of the level of location in the well of silty interlayers, and the height of the shell is not less than two diameters of the reinforcing cage of the pile plus the height of the sludge is N and exceeds the height of the specified zone on each side of it not less than the size of the pile. In this case, the shell is fixed to the reinforcing cage in its vertical, inclined or horizontal position. The shell can be formed of several layers by wrapping the perimeter of the reinforcing cage with a geotextile cloth and then securing it to the reinforcing cage, preferably with a knitting wire. The shell can be formed by wrapping around the perimeter of the reinforcing cage with a geotextile cloth along a helix. The reinforcing cage can be wrapped around the perimeter with a geotextile cloth not less than the height of the reinforcing cage placed in the well.

The invention is illustrated by drawings, where

- figure 1 shows a well drilled in the ground with a casing;

- figure 2 shows that the walls of the well are kept from collapsing by a casing pipe, into which a reinforcing cage with an attached sheath - a "stocking" of geotextiles is inserted;

- figure 3 shows that as the casing is removed, the cast concrete mixture is laid, and at the intersection with the sapropel, geotextile serves as an impermeable fixed formwork for the cast concrete mixture.

The method of constructing a bored pile in the soil with silty layers is implemented as follows. After drilling in the casing 2 of the well 1, the level (depth) of the bed of sludge (sapropel) “N” and its power are determined. On the reinforcement cage 3 put on a "stocking" of geotextile 4 (figure 2) and fix it to the frame with knitting wire. The size of the geotextile “stocking” is determined from the condition that the geotextile overlap of the sapropel layer “A” on each side (FIG. 2) was not less than the diameter d of the borehole (piles), that is, A> d, then the height of the shell (H + 2A). The diameter of the geotextile “stocking” should be equal to the diameter of the well (piles). The reinforcing cage 3 is lowered into the casing 2 and concreting the well 1 by cast concrete using the VPT method. In the process of concreting the pile pile, after lifting the casing 2, from the pressure of the concrete mixture, the “stocking” of geotextiles takes the form of a column with a diameter d and prevents the concrete mixture from being squeezed out into the sapropel layer, while simultaneously forming the corrective protective concrete layer. In this case, the “stocking” of geotextiles (for example, the Habesker Stabilenka 400 fabric) perceives the pressure difference between the concrete mixture (inside) and the sapropel layer (outside). If it is necessary to install a bored pile in silty soils (with underlying solid soils), the “stocking” of geotextile 4 is worn over the entire length of the reinforcement cage 3. The frame can be wrapped around the perimeter with a geotextile cloth to ensure adjacency along the face of the layer once or repeatedly as separate segments along an arc circles connected by a knitting wire to the reinforcing cage, and along a helix with overlapping at least a quarter of the width of the geotextile panel, which eliminates the need for yōkan liquid phase.

Claims (6)

1. A method of constructing a bored pile in soil with silt interlayers, including forming a well in the ground with a casing in it, determining the level of silt interlayers in the well, immersing the reinforcing cage in the well with a fixed formwork in the form of a geotextile sheath fixed on it in the zone of the location in the well of silty interlayers, and the height of the shell is not less than two diameters of the reinforcing frame of the pile plus the height of the sludge N exceeds the height of the specified zone on each side by at least the diameter of the pile. 2. The method of constructing a bored pile in the soil with silt layers according to claim 1, wherein the sheath is fixed to the reinforcing cage in its vertical or inclined position. 3. The method of constructing a bored pile in the soil with silt layers according to claim 1, in which the shell is fixed to the reinforcing cage in its horizontal position. 4. The method of constructing a bored pile in soil with silt layers according to claim 1, wherein the shell is formed of several layers by wrapping a geotextile fabric around the perimeter of the reinforcing cage and then securing it to the reinforcing cage, preferably with knitting wire. 5. The method of constructing a bored pile in the soil with silt layers according to claim 1 or 4, wherein the shell is formed by wrapping a geotextile with a geotextile cloth along a helical line around the perimeter of the reinforcing cage. 6. The method of constructing a bored pile in soil with silt layers according to claim 1, wherein the reinforcing cage is wrapped around the perimeter with a geotextile cloth not less than the height of the reinforcing cage placed in the well.

Images