RU2498017C1 - Method to submerge piles by pressing in - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: method of pile submersion by pressing in includes insertion of a pile pressing plant into a working device, which is installed vertically and pressed in a clamping mechanism, the pile is submerged for the value of travel of the pressing mechanism hydraulic jack piston (up to 1.0 m), the pile is undone in the working device of the plant, stems of the pressing mechanism hydraulic jacks are raised to the upper position (idle running), the pile is again pressed, and the cycle is repeated again until the pile is submerged to the design depth. In layers of dense soils with soil resistance to submersion, exceeding the maximum force of the pressing plant as the minimum speed of submersion is achieved, the pile motion is periodically stopped due to reduction of pressing force to zero value, the pile is withdrawn from soil by the value equal to the length of its side, and then the pile is lowered to the previous level at the minimum pressing force, afterwards the pressing force is increased to the maximum value, and the pile is submerged by the made step of the process cycle of alternating pressing-withdrawal-pressing.

EFFECT: provision of reliability of a process of pile submersion by pressing method through guaranteed reach of a bearing layer via layers of dense soils.

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Description

The invention relates to the field of construction and can be used when immersing piles by pressing them into interlayers of dense soils with soil resistance exceeding the maximum force of the pressing unit.

A known method of immersion of piles by indentation, which includes applying static indentation force to a pile by various methods (V. Burov, Research of the processes of immersion of piles by the indentation method in order to substantiate the selection of optimal parameters of pile-pressing installations: abstract of dissertation of Candidate of Technical Sciences. - Omsk, 1969 . - 20 s.).

The disadvantages of the method are the impossibility of reaching the pile of the bearing layer of the soil when immersed in the prevailing dense soils (deformation modulus E> 14 MPa, yield index I _L <0.3) when the soil resistance to immersion exceeding the maximum force of the pressing unit.

Closest to the proposed technical solution is a method of immersing piles by indentation, which involves loading piles into an operating unit of an impression installation, which is installed vertically and clamped in the clamping mechanism, pile is immersed by the piston stroke of the hydraulic jacks of the indentation mechanism (up to 1.0 m), the piles are expanded in the working body of the installation, raise the hydraulic ram jacks of the indentation mechanism to the upper position (idle), clamp the pile again and the cycle is repeated first until the pile is immersed in the design deep depth. When piles are immersed in interlayers of dense soils with an immersion resistance exceeding the maximum indentation force provided by the installation, in which the immersion is stopped, the pile is removed and the special methods described below for lowering the soil resistance to immersion are used (Guiding technical material. RTM 36.44.12.2-90. Design and installation of foundations from piles, immersed by the indentation method. - SPb .: VNIIGS, 1992. - 46 p.).

However, the considered method has the following disadvantages: extraction of piles from the soil and the subsequent use of special methods to reduce soil resistance to immersion in the form of drilling leader wells, loosening the soil with a screw, the use of antifriction coatings of the pile surface lead to a decrease in labor productivity by more than 2 times, an increase in the cost of work 40% and reduce the bearing capacity of piles on the ground to 20%. In addition, it is technically difficult to remove submerged piles from a depth of more than 10 m, which requires a change in design and the immersion of additional piles.

The objective of the solution to which the present invention is directed is to ensure the reliability of the pile sinking process by the indentation method.

The method of immersing piles by pressing includes loading piles into the working body of the pressing installation, which is installed vertically and clamped in the clamping mechanism, pile is immersed by the size of the piston stroke of the hydraulic jacks of the pressing mechanism (up to 1.0 m), the piles are expanded in the working body of the installation, and the hydraulic jacks are raised pushing the mechanism into the upper position (idle), again clamp the pile and the cycle is repeated first until the pile sinks to the design depth. At the same time, in interlayers of dense soils, when the soil resistance to immersion exceeds the maximum force of the pressing installation, when the minimum speed of immersion is reached, the movement of the piles is periodically stopped by reducing the pressing force to zero, the pile is removed from the soil by an amount equal to the length of its side, and then the pile is lowered to the previous level with a minimum indentation force, after that, the indentation force is brought to the maximum value and the pile is immersed in the adopted step of the technological cycle alternate indentation-extraction-indentation.

This action provides a reduction in the mass of soil attached to the pile and a decrease in lateral friction forces, by analogy with the effect of “pacing” casing strings in drilling if they are caught by rock. As a result, the piles slip relative to the near-pile soil and exclude its “sticking” to the side faces of the piles.

During pile driving, the number of alternate indentation cycles is determined depending on specific engineering and geological conditions, including the occurrence of soils of different densities in the pile driving interval.

The step size of the alternate indentation-extraction-indentation technological cycle equal to the length of the side of the prismatic pile (in cross section) was determined by the authors on the basis of statistical processing of experimental data obtained under production conditions on a significant number of real construction objects. In the course of experiments in various engineering and geological conditions, the dependences of the change in the depth and time of the pile sinking on the change in the alternate step of indentation-extraction-indentation were studied. So, it was found that with a step greater than the length of the side of the prismatic pile, when the pile is removed, the soil can be “sucked” into the cavity under the fifth pile, which prevents further pressing of the pile, in addition, the energy consumption for removing the pile increases. Reducing the step size less than the length equal to the side of the prismatic pile does not lead to a noticeable decrease in the mass of soil attached to the pile and a decrease in lateral friction forces. As a result, the indentation of the piles is stopped when the resistance of the soil to immersion exceeding the maximum force of the pressing installation is reached.

The method of dipping piles by indentation is illustrated, in which figure 1 presents the steps of indentation of piles;

on figa - the stage at which stop the movement of piles when the resistance of the layer of dense soil to immersion exceeding the maximum force of the pressing unit;

on figb - the stage of extracting piles from the soil by an amount equal to the length of its side d;

on figv - the stage at which the pile is lowered to the previous level with minimal pushing force;

Fig.1d is the stage at which the indentation force is brought to the maximum value and the pile is immersed in the adopted step of the alternate indentation-extraction-indentation technological cycle;

on fig.1d - the stage of extraction of piles from the soil by an amount equal to the length of its side d.

The method is implemented as follows.

Pile 2 is pressed in from the soil surface by the pile-in installation 1. When deepened into dense soils upon reaching level 3, at which the immersion resistance reaches a value exceeding the maximum indentation force, the movement of the pile 2 is stopped by reducing the indentation force to zero, then pile 2 removed from the soil by a value of q equal to the length of its side to level 4, after which the pile 2 is lowered to the previous level 3 with a minimum indentation force, and the indentation force is brought to the maximum values 2 and submerged pile indentation on the received step up to the level 5.

These processes are repeated as many times as necessary to immerse the piles to the design level through the occurring layers of dense soils.

As a result, it is ensured that the piling immersion process is reliable by the indentation method by guaranteed achievement of the bearing layer.

Claims (1)

The method of immersing piles by pressing includes loading piles into the working body of the pressing installation, which is installed vertically and clamped in the clamping mechanism, the pile is immersed by the piston stroke of the hydraulic jacks of the indentation mechanism (up to 1.0 m), the piles are expanded in the working body of the installation, the hydraulic jacks are lifted pushing the mechanism into the upper position (idle), again clamp the pile and the cycle is repeated first until the pile is submerged to the design depth, characterized in that in interlayers of dense soils when copro when the soil is submerged, exceeding the maximum force of the pressing unit when the minimum speed of immersion is reached, the movement of the pile is periodically stopped by reducing the pressing force to zero, remove the pile from the soil by an amount equal to the length of its side, and then lower the pile to the previous level with minimal effort indentations, then bring the indentation force to the maximum value and immerse the pile on the accepted step of the alternate indentation-extraction-indentation technological cycle Nia.

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