RU2706848C1 - Bored pile manufacturing method - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to construction, namely, to production of bored piles. Method includes drilling of well, installation of reinforcement frame in it with fixed on it tubes-injectors, supply of concrete solution to well and when it reaches 5–10 % strength of measuring device, lowering it in series into tubes-injectors, with pitch of not more than 300 mm, temperature of pile concrete is measured. Spatial temperature distribution charts are constructed and minimum temperature zones are determined. After that, without removing the measuring device from one of the injector tubes, through the free tube-injectors into the minimum temperature zones, the reinforcing solution is successively injected under a pressure of not less than 50–70 % from concrete strength achieved by the moment of injection and with temperature above temperature of minimum temperature zones to temperature equalization in these zones. Then the pile is held for 15–60 minutes. Temperature is measured and, in case of temperature reduction, solution injection is repeated.

EFFECT: technical result consists in enabling control of pile shaft continuity and elimination of detected defects during its manufacturing.

4 cl, 1 dwg

Description

The invention relates to the construction, and in particular to the technology of manufacturing bored piles.

The main problem encountered in the manufacture of piles in the ground is to ensure the integrity of the pile shaft. Concreting of bored piles causes defects in the pile shaft, for example, due to exceeding the permissible rate of rise of the concrete pipe, which creates a vacuum in the well and the formation of unpredictable air and water interlayers in the pile shaft, soil dumping from the walls into the cavity of the well and soil penetration into the concrete “body” of the pile and other unfavorable technological factors leading to the formation in the concrete “body” of the pile of decompressed zones, voids and sections with reduced concrete strength, which, in turn, leads to a decrease in the overall strength and reliability of the pile. Typically, bored piles are checked for defects in them, for example, by seismoacoustic or ultrasonic methods after setting concrete mix laid in the well and gaining hardened concrete of a certain strength when it is no longer possible to eliminate these defects (voids). As a result, the pile with defects is rejected and a new duplicate pile is performed instead, which leads to a significant increase in material and labor costs for the construction of the pile foundation.

In order to reduce material and labor costs for the manufacture of piles, the quality of concreting in the pile shaft and the presence of defects should be determined immediately after filling the well with concrete mixture, that is, before hardening (formation of a rigid spatial structure) of concrete begins. The gel state of the concrete is maintained, depending on the composition of the concrete mixture, for a short period of time - from 1 hour to 4-5 hours after it is laid in the well. Piles are usually concreted with concrete with high grades of cement and concrete. As a rule, cements with a high content of tricalcium silicate and aluminate are used. Hydration of such cements produces a significant amount of heat. Moreover, the more heat is generated, the higher the class (strength) of concrete. By measuring the temperature of the set concrete mixture, already at this stage it is possible to evaluate the zones of reduced strength at a lower temperature in comparison with the rest of the concrete mass.

For example, there is a known method for controlling the manufacture of piles, including forming a well, installing a reinforcing cage in it with temperature sensors mounted on it, laying communication lines, supplying a cured material to the well and monitoring its temperature using a system of installed sensors (RF Patent No. 2538362, IPC G01K 13/00, E02D 5/34, published 01/10/2015, bull. No. 1). However, a reinforcing cage with values of heat capacity and thermal conductivity that are different from concrete can have a significant effect on the readings of sensors mounted on it.

A known method for assessing the continuity of a concrete pile, including drilling a well, lowering the reinforcing cage and installing measuring tubes inside and outside the reinforcing cage along the longitudinal axis of the pile, supplying concrete to the well and measuring the temperature of the concrete during pouring by moving the measuring device inside the measuring tubes. Then, in real time, the temperature profile of the pile body is built, which is compared with the profile built for ideal conditions, and the presence and position of pile defects are determined by anomalous temperatures. As a remedial measure, the authors of the known method propose the extraction of concrete from the zone of abnormal temperatures, washing with water and re-pouring concrete (US Patent No. 6,783,273, IPC G01N 25/00, 25/72, G01K 3/00, publ. 31.08.2004). This well-known solution is taken as a prototype.

The technical result, to which the proposed technical solution is aimed, is to increase the reliability of bored piles by providing the ability to control the integrity of the pile shaft and eliminate identified defects during the work process, as well as reducing material and labor costs.

The claimed technical result is achieved in that in a method including drilling a well, installing a reinforcing cage in it with measuring tubes fixed to it, supplying a concrete mortar to the well and holding it until it hardens, according to the invention, to the inner side of the reinforcing cage in advance, with a given step at least three injector tubes made with slotted openings closed by elastic cuffs acting as check valves in the cross section and the entire length of the piles are secured to which, after supplying concrete mortar to the well and achieving 5-10% strength, using a measuring device, lowering it down the entire pile shaft, measure the temperature of concrete piles with a step of no more than 300 mm, build spatial temperature distribution graphs and determine the minimum temperature zones, then, without removing the measuring device from one of the injection tubes, through the free injection tubes into the zones of minimum temperatures, the strengthening solution is sequentially injected under a pressure of at least 50-70% of that reached to the moment of injection of concrete strength and with a temperature above the temperature of the zones of minimum temperatures until the temperature is even in these zones, then the pile is kept for 15-60 minutes, the temperature is measured and, if the temperature drops, the solution is repeated.

Injection tubes are made with slotted holes with a length of at least 100 mm and arranged in increments equal to the step of determining the temperature of concrete in the pile body.

As an injectable solution, quick-hardening cements with increased exothermic ability are used.

The essence of the proposed method is illustrated by drawings, where in FIG. 1 shows a vertical section of a pile and a horizontal section of a pile with installed measuring tubes-injectors.

A method of manufacturing a bored pile is implemented as follows.

At least one of the known methods forms a well 1. On the inner side of the reinforcing cage 2 parallel to its longitudinal axis, at least 3 special tubes — 3a, 3b, 3c — are attached uniformly, with a given step in the cross section, designed to measure the temperature in the body of the pile and injection of a strengthening solution. The tubes are perforated, with slotted holes of at least 100 m in length, located in increments equal to the step for determining the temperature of concrete in the pile body and closed with elastic cuffs 4, which act as check valves. Next, the reinforcing cage is lowered into the well and the well is poured with a solution of concrete. After filling the well, the solution is kept for 1-6 hours until it reaches 5-10% strength. After that, the measuring device 5 is lowered sequentially into all three measuring tubes-injectors 3a, 3b and 3c, for example, a thermometric probe connected to the recording analyzer-analyzer 8 and allowing to determine the concrete temperature with an accuracy of at least 0.1 degrees. Then, along the height over the entire cross-section of the pile with a step of not more than 300 mm, temperature is measured. The measurement results are automatically sent to the recording device 8 and according to the results of measurements in real time, spatial graphs of the temperature distribution in the pile body are built, which determine the location of the defects of the pile - zones of concrete with a lower temperature compared to the rest of the concrete mass. This allocation of zones of reduced strength can already be done with a difference in temperature from the rest of the concrete mass of 2-3 degrees. After determining the zones of reduced temperature, without removing the temperature probe 1 from the last well (3c), it is installed at the level of the weakened zone to control the temperature in the process of eliminating the zones of reduced concrete strength. To eliminate the zone of reduced concrete strength, a special reinforcing concrete solution 7 is sequentially pumped into it through two other free injection tubes (3a and 3b). The hardening solution is injected using a special packer 6 into the zone of minimum temperatures, while the packer is installed at a level of not less than 0.9 m below and 0.9 m above the weakened zone. A special reinforcing mortar, which is a cement solution with a high content of tricalcium silicate and aluminate, heated to a temperature above the temperature of the weakened concrete zone by 1 degree, is pumped to a temperature increase in the probe of at least 0.5 degrees. Then the packer is rearranged into the second injector tube and, in the same order, the reinforcing solution is heated, which is heated to a temperature 1 degree higher than that achieved in the previous injection, until the temperature in the probe is also increased by 0.5 degrees. Then, both injection tubes are washed with water at a temperature equal to the temperature of the solution and the temperature is measured in the weakened zone. It is believed that the weakened zone is strengthened sufficiently if its temperature does not drop within 30 minutes. If the temperature of the weakened zone decreases within 30 minutes, the injection operation described above is repeated. After reaching the temperature values in the weakened zones of concrete corresponding to the main temperature background of the concrete, a control temperature measurement along its entire length is carried out in the pile.

As an injectable hardening solution, quick hardening cements with increased exothermic ability are used.

At the end of the injection, the injection tubes are freed from the solution, for example, by flushing or drilling with flushing. In the process of hardening concrete, pile-injectors can be used to control the strength of concrete, for example, by the ultrasonic method.

Claims (4)

1. A method of manufacturing a bored pile, including drilling a well, installing a reinforcing cage in it with measuring tubes fixed to it, supplying a concrete mortar to the well and holding it until it hardens, characterized in that it is advance to the inside of the reinforcing cage with a given step in the transverse at least three injector tubes made with slotted openings closed by elastic cuffs acting as check valves in the cross section and the entire length of the piles, in which, after feeding into the importance of concrete mortar and its achievement of 5-10% strength, measuring device, lowering it down the entire pile shaft, with a step of no more than 300 mm measure the temperature of concrete piles, build spatial temperature distribution graphs and determine the minimum temperature zones, after which, without removing a measuring device from one of the injection tubes, through free injection tubes into the zones of minimum temperatures, with the help of a packer, successively inject the strengthening solution under a pressure of at least 50-70% of that achieved by the time nektirovaniya and concrete strength at a temperature above the minimum temperature of the temperature zones to equalize the temperature in these zones, then the pile is kept for 15-60 minutes, the temperature is measured in the case of lowering the temperature of the solution injection is repeated. 2. The method according to p. 1, characterized in that the injector tubes are made with slotted holes with a length of at least 100 mm and arranged in increments equal to the step of determining the temperature of the concrete in the pile body. 3. The method according to p. 1, characterized in that the packer for injection of a strengthening solution is set at a level of not less than 0.9 m below and 0.9 m above the zone of minimum temperatures. 4. The method according to p. 1, characterized in that as an injectable strengthening solution used quick-hardening cements with high exothermic ability.

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