RU2737303C1 - Bored pile reinforcement method - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to construction and can be used for prevention and correction of emergency situations when erecting heavy buildings and structures on foundations of deep bored piles of large diameter, in the process of their manufacturing defects in the form of voids inside the pile concrete body are installed and/or design strength of concrete piles is not achieved. Bourbon pile reinforcement method produced by well borehole piles drilling, its filling with concrete and merging bored pile with foundation plate. Method comprises preliminary determination of solidity and strength of cross-section of boron-boring shaft by drilling additional wells and sampling cores therefrom. Then, after borehole drilled cores, hollow metal rods with length exceeding the length of bored pile are introduced with perforated tips with simultaneous supply of cement solution under high pressure, which fills defects detected during coring. Then, when the perforated tip is immersed below the bored pile edge, high-pressure cementing of its base is performed. Then upper parts of hollow metal rods are equipped with anchoring plates and are embedded in foundation plate body, thus forming additional spatial frame from hollow metal rods interacting with bored pile barrel and resting on its reinforced base.

EFFECT: technical result consists in improvement of carrying capacity of pile, providing maximum effective use of long bored piles of large diameter with shaft defects made in soil for reducing construction cost and reducing time for performance of works.

1 cl, 2 dwg

Description

The invention relates to construction and can be used to prevent and correct emergencies during the erection of heavy buildings and structures on foundations of deep bored piles of large diameter, during the manufacture of which defects in the form of voids inside the concrete body of the pile were established and / or the design strength of concrete was not achieved piles.

In many cases, high-rise buildings are densely built up and significant specific loads are transferred to a relatively small area of the foundation, which leads to the need to use a deep foundation to transfer the load from the aboveground structure to denser, stronger, low-compressive, deep-lying soil layers. For this, drill piles of large length and large diameter are used in the range of d = 1.0-1.8 m and more. Given the limited dimensions of the foundation patch, the total number of piles in the foundation can be small, and each pile of the pile field must be guaranteed to provide a bearing capacity, often measured in several hundred, and sometimes several thousand tons. Thus, each individual pile is a very important element of the overall bearing capacity of the foundation and therefore the reliability of the entire building.

When manufacturing piles of large length and large diameter, it is necessary to strictly observe the drilling technology, submersion of the frame, the requirements for laying and gaining strength of concrete. If in any pile after manufacture defects of the solidity are revealed or, according to the test results, the required bearing capacity is not achieved, then such a pile, in most cases, must be replaced with a new one. However, new piles cannot always be made due to the fact that when making new piles in a limited spot of the foundation and in the presence of a number of piles, the minimum inter-pile distance may be violated, in addition, piles with defects may not be single, but constitute a significant part of all completed piles. With the risk of re-formation of such defects in re-drilled piles, given the very significant costs of additional drilling, as well as the difficulty of moving the drilling rig within the field of actually completed piles, re-drilling may not lead to the desired result and greatly increase the cost of construction.

There is a known method of strengthening foundations, in which a layer of weak soils is fixed using jet geotechnology, which makes it possible to significantly increase the bearing capacity of the base (SU 1733567 A1, class E02D 3/12, 1992 - analogue), including those that include old foundations with insufficient bearing capacity.

The disadvantage of this solution is the high cost of this method of strengthening, since the entire or almost the entire array of soft soil must be fixed to obtain the same characteristics at each point of the array after it has been reinforced.

Known invention (RU 2462557, E02D 5/46, 2012 - prototype), including drilling a well for a bored pile shaft, filling it with concrete and combining a bored pile with a foundation slab in order to increase the bearing capacity of a short bored (soil-cement) pile by aligning it with longer, small diameter piles passing through its body at predetermined angles.

The disadvantage of this invention is the absence of a rigid connection between the large diameter soil-cement pile and the inclined small diameter piles, which leads to insufficient rigidity of their single structure under dynamic loads. In SP 24.133330.2011, p. 12.12 it is noted: "The upper ends of the piles must be rigidly embedded in the grillage to a depth determined by a calculation that takes into account seismic loads"

The technical result is the most effective use of long bored piles of large diameter made in the ground with shaft defects to reduce the cost of construction and shorten the time of work.

The technical result is achieved due to the fact that in the method of strengthening a bored pile, including drilling a well for a bored shaft, filling it with concrete and combining a bored pile with a foundation slab according to the invention, the continuity and strength of the section of the bored shaft are preliminarily determined by drilling additional wells and taking cores from them , then, after drilling out the cores, hollow metal rods with a length greater than the length of the bored pile are introduced into the formed wells after drilling out the cores with the simultaneous supply of cement slurry under high pressure, which fills the defects revealed in the process of drilling the cores, then when the perforated tip is immersed below the tip of the bored high pile cementation of its base, then the upper parts of the hollow metal rods are supplied with anchoring plates and embedded in the body of the foundation slab, forming an additional spatial frame of hollow metal rods interacting with the bored pile shaft and resting on its reinforced base.

The scientific novelty of the invention lies in the fact that the proposed method of strengthening a bored pile, due to the use of modern geotechnologies, allows to preserve for further use an element with a revealed broken strength and continuity and, as a result, form a foundation element in the soil with a high bearing capacity.

The essence of the invention is illustrated by the drawing, where FIG. 1 shows a long and large diameter bored pile with identified defects inside the concrete body, as well as its cross-section shown in FIG. 2.

The method of reinforcing a bored pile is implemented as follows: the necessary studies of piles 1 are carried out for the presence of voids and defects 2 in their body, formed during the installation of piles 1, by drilling holes 3 with core sampling. If piles 1, which need to be strengthened, are identified, the voids 2 formed during the concreting of piles 1 are injected by filling these voids by introducing vertical metal rod elements 4 into the body of the weakened pile 1, placed in vertical through holes 3 previously made in the body of the pile circular cross-section and small diameter, while through the hollow barrel of the metal rod element 4 in the process of its deepening through the cylindrical wells 3, high-pressure cementation is carried out and the filling of defects 2 inside the concrete body of the pile 1 through the perforated tip 5 of the hollow metal rod 4, then when the tip 5 is immersed below the tip of the pile 1, high-pressure cementation of the base 6 is performed, after which the rod elements 4 inserted into the pile are anchored into the body of the foundation slab 8 through special plates 7, forming an additional spatial frame of rods interacting with the body of the pile 1, resting on a reinforced soil base 6.

Claims (1)

A method of strengthening a bored pile obtained by drilling a well for a bored shaft, filling it with concrete and combining a bored pile with a foundation slab, characterized in that the continuity and strength of the section of the bored shaft is preliminarily determined by drilling additional wells and taking cores from them, then into the formed wells after drilling out the cores, hollow metal rods with a length exceeding the length of the bored pile are introduced with perforated tips with simultaneous supply of cement slurry under high pressure, which fills the defects revealed during the drilling process, then when the perforated tip is immersed below the tip of the bored pile, its base is cemented the upper parts of the hollow metal rods are supplied with anchoring plates and embedded in the body of the foundation slab, forming an additional spatial frame of hollow metal rods interacting with the drill barrel on a pile and resting on its reinforced base.

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