RU2634759C1 - Method of auger pile construction - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention can be used for manufacturing auger piles with shoring of existing foundations. The method for constructing an auger pile comprises drilling a well, filling it with a concrete mixture and putting the soil of the well walls under pressure. After the well is filled with the concrete mixture, a conductor pipe is installed from above, made with an elastic shell around the circumference to seal the annulus of the well; the compressed air or water is fed into the shell at a pressure of up to 0.5 MPa by means of an autonomous packer until the shell size increases, exceeding the annulus by 20-30%. The soil of the well walls is put under pressure by feeding the concrete mixture under an excess pressure of 0.2-0.3 MPa for 5-10 minutes through the conductor pipe, and then immersing it in the concrete mixture of the reinforcement cage.

EFFECT: increased bearing capacity of the pile by effective compaction of the well walls, reduced consumption of the concrete mixture due to elimination of leakage during the pressing process, increased labour productivity.

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Description

The invention relates to construction and can be used for the manufacture of bored piles while strengthening existing foundations.

With the strengthening of existing foundations from drilling wells, the soil under the foundations is softened and the foundation gives sediment. Bored piles perform pressure testing of the soil with excess pressure. Moreover, the higher the pressure of the crimping, the higher the quality of the injection piles and less deformation of existing foundations from drilling beneath them.

A known method of device injection piles, which consists in drilling in the soil of the hole with hollow airtight augers, followed by pressure testing of the soil surrounding the well by supplying concrete mortar through the cavity of the screws of the drill stand and the gradual extraction of the screws with simultaneous pressure testing of the soil.

The disadvantage of this method is the impossibility of raising the pressure of pressure testing in the well higher than the hydrostatic pressure of the solution. This is due to the presence of gaps between the borehole wall and the cuttings that feed upward along the auger flange.

This disadvantage is eliminated by the fact that an artificial plug is created artificially that separates the lower part of the well to be crimped from its upper part. Using this method, it is possible to raise the pressure of the crimping no higher than 0.3-0.4 MPa only for a short time, and then the plug breaks and the solution exits, which is accompanied by a drop in its pressure / RF Patent No. 95637, cl. E02D 5/46 publ. 2010 y. /

There is a method of constructing a bored pile, including drilling a well, lowering the reinforcing cage into it, filling it with concrete mixture and pressing the soil into the walls of the well by tamping. / RF patent №2525896, class. E02D 5/42, publ. 10.61.2014 /.

The closest analogue to the proposed one is a method of constructing a bored pile, including drilling a well, filling it with concrete mixture and periodically pressing the soil into the well walls by feeding the concrete mixture into the well under a pressure of at least 4 kg / cm ² / RF Patent No. 2561093, cl. E02D 33/00, publ. 01/20/2015 /.

The disadvantage of this method is the inefficiency of soil compaction, which entails an overrun of the binder and a low bearing capacity of the pile.

The technical problem is to increase the bearing capacity of the piles by effectively compacting the walls of the soil of the well and reducing the consumption of concrete mixture.

The problem is solved in such a way that in the method of constructing a bored pile, including drilling a well, filling it with concrete mixture and crimping the soil of the walls of the well, according to the invention, after filling the concrete with the mixture of the well, a conductor pipe made with an elastic shell around the circumference to seal the annular the space of the well, compressed air or water is supplied into the shell under pressure up to 0.5 MPa by means of an autonomous packer until the shell size exceeds the annulus a space of 20-30%, and produce molding wellbore soil by feeding concrete mix pressurized 0,2-0,3MPa for 5-10 min through-conductor tube, followed by immersion in the concrete mixture the reinforcing cage.

The proposed method differs from the known one in that after filling the well with concrete mixture, a conductor pipe is installed on top, made with an elastic shell around the circumference to seal the annulus of the well, compressed air or water is supplied into the shell under a pressure of not more than 0.5 MPa through an autonomous packer up to increase the size of the shell, exceeding the annular space by 20-30%, and perform pressure testing of the soil of the walls of the well by supplying concrete mixture under an excess pressure of 0.2-0.3 MPa for 5-10 min h through a conductor pipe, followed by immersion in the concrete mixture of the reinforcing cage.

Isolation of the annulus of the well during pressure testing of the walls of the well with concrete allows increasing the pressure of pressure testing, thereby increasing the degree of compaction of the soil with a minimum consumption of concrete, speeding up the construction of piles and reducing the complexity of the process. The selected crimping parameters ensure optimal penetration of the solution into the soil of the borehole walls and should not exceed hydraulic fracture pressure, and the air or water supply pressure parameters provide inflation of the shell and maximum isolation of the crimping zone.

The method is illustrated in the drawing, which shows a diagram of the construction of a bored pile.

A bored pile is constructed as follows.

In the upper part of the well 1, a conductor pipe 2 is installed, into which a shutter 3 is placed, through which a solution 4 is supplied under pressure into the well 1. In order for the concrete not to exit to the day surface in the lower part, on the surface of the conductor pipe 2 an elastic packer 5 is installed in the annulus, into which compressed air or water is supplied into the elastic shell under pressure through an additional tube 6 to increase its volume in order to overlap the annulus and separate the lower pressure Asti hole 7 from the top, with the atmosphere communicating 8 (FIG. 1).

The method is as follows.

Using a drill stand made of hollow screws, a well is drilled and then filled with fine-grained concrete. After filling it with concrete, a conductor pipe 2 is placed at a predetermined depth, then an obturator 3, then the packer 5 is activated by pumping it from above with hydraulic fluid (water) to a pressure exceeding the compression pressure by 10-20%. In this case, the elastic expandable packer increases in volume and, abutting against the walls of the well, divides the well into two cavities, the lower of which turns into a sealed one. Then, while holding the hydraulic fluid pressure in the expansion packer, concrete is pumped from above through a conductor pipe into the lower sealed part of the well and the specified pressure of the pressure is maintained for a predetermined time interval, usually 5-10 minutes. The length of the well interval to be crimped is determined by the difference between the lengths of the conductor pipe and the depth of the well. In the event of the concrete mortar coming to the surface, the pressure in the packer is increased until the mortar is stopped. After crimping the bottom of the well in the depth interval from its bottom to the packer installation level, the pressure in the packer is released to zero, while the shell decreases in volume and the conductor pipe is raised, the crimping operation described is repeated, and so on to the crimping depth specified in the design. After filling the well with concrete mixture and crimping its walls, the reinforcing cage is immersed in concrete, on which the device of the injection pile is completed.

The proposed method allows to reduce the consumption of concrete mixture by eliminating leaks in the process of pressure testing and reducing the time of the crimping process and increasing labor productivity.

Claims (1)

A method of constructing a bored pile, including drilling a well, filling it with concrete mixture and crimping the soil of the walls of the well, characterized in that after filling the concrete with the mixture of the well, a conductor pipe is installed on top, made with an elastic shell around the circumference to seal the annulus of the well, and the shell is compressed air or water under pressure up to 0.5 MPa by means of a stand-alone packer until the shell size increases by 20-30% exceeding the annulus and the soil is pressed the walls of the well by supplying concrete mixture under an excess pressure of 0.2-0.3 MPa for 5-10 minutes through a conductor pipe, followed by immersion in the concrete mixture of the reinforcing cage.

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