UA19875U - Drill-injection suspended piles with cement widening - Google Patents

Abstract

Drill-injection suspended piles with cement widening relate to the field of building and are relates to construction of pile basements.

Description

Description of the invention

The useful model refers to the field of construction and concerns the construction of pile foundations. 2 When building houses and structures on weak and shaky soils - loam, sandy loam, dusty loam, sand, etc. often involve the construction of pile foundations. The type and number of piles are determined by the project, which calculates the load-bearing capacity of the piles, that is, the amount of vertical load that the pile can withstand without destruction or vertical displacement relative to the depth of its construction due to interaction with the soil. The following types of piles are known. 70 According to the conditions of interaction with the soil, piles are divided into standing piles and hanging piles (1). Piles-stands are built to the depth of the solid soil, which has a modulus of deformation E »50Mpa. The bearing capacity of such piles is determined by the bearing capacity of the soil at the base of the pile and the strength of the hardened cement mixture used to fill the well. Not considered in this case.

The following types of piles are distinguished according to the method of sinking into the soil |11: 12 a) driven piles, which are sunk into the soil without excavating it with the help of hammers, etc. Not considered in this case. d) boreholes that are installed in the ground by filling drilled wells with concrete (drilling) or cement (drill injection) mixture;

Drilled piles are divided according to the construction method into: a) bored piles of continuous cross-section with and without extensions, which are concreted in wells drilled in dusty-clay soils above the groundwater level without fixing the walls of the wells, and in any soils below the groundwater level - with fixing the walls of the wells with a clay solution or inventory pipes that are pulled out; b) boring punches of round cross-section, which are arranged using a multi-section core; c) drill presses with a compacted hole, installed by tamping crushed stone into the well hole; d) drill presses with a camouflaged heel, which are arranged by drilling wells with the subsequent formation of expansion by explosion and filling the well with a concrete mixture; e) injection wells with a diameter of 0.15-0.25 m, arranged by injection (injection) of fine-grained concrete mixture or cement-sand solution into drilled wells; o f) piles-pillars, which are arranged by drilling wells with or without expansion, placing in them a cement-sand solution and sinking into the wells cylindrical or prismatic elements of solid cross-section with sides with a diameter of 0.8 m or more; so zh) bored piles with a camouflage heel, which differ from bored piles with a camouflage heel Ge") (see subsection "d") in that after the formation of a camouflage expansion, a reinforced concrete pile is lowered into the gap. 3o Boro-injection piles are built to the depth of solid soil, which has a modulus of deformation --

E»5 OMpa. The bearing capacity of such piles is determined by the bearing capacity of the soil at the base of the pile and the strength of the hardened cement mixture injected into the well. In this case, they are not considered.

Boroinjection hanging piles rest on compressible soils and transfer the load to the base soils through the lateral surface and lower end. The load-bearing capacity of a hanging borehole injection pile is determined by the expression: 79 already host those all that with where: ур, жов, вся 7 coefficients of working conditions; )» KE - estimated soil resistance under the lower end of the pile;

A - pile bearing area; и - perimeter of the cross-section of the pile trunk; - І; - calculated resistance of the i-th soil layer on the lateral surface of the pile trunk; with A; - strength of the i-th soil layer.

The closest to the proposed construction are hanging borehole injection piles, which are arranged by (ee) pumping (injection) of cement or cement-sand solution into drilled wells |1) (Prototype). - 50 Adjustment of the bearing capacity of a borehole injection pile is possible by increasing the depth or diameter of the well, as well as by increasing the number of piles. The listed methods lead to a significant increase in the cost of construction.

The useful model is based on the task of increasing the load-bearing capacity of a hanging borehole injection pile.

This goal is achieved by creating cement expansions around the injection piles, which are formed when cement or cement-sand solution is injected into the containing soil through the side surfaces of the piles.

Cement expansions are created by injecting a cement or cement-sand solution into the ground through special injectors installed in the well. Structurally, the injector (Fig. 1) is a perforated pipe 1, where the perforation 2 is closed by rubber cuffs 3. The end hole of the pipe is closed with a cap 4, which prevents soil from hitting the injector when it is immersed in the well. In order to maintain the stability of the gap between the pipe and the 60 walls of the well, the injector is provided with a centralizer 5. The injector material, quantity, location and geometric shape are determined by the project.

If necessary, if the well is more than 6 m deep, the injector can be composed of several parts and have a welding or coupling connection.

The creation of a cement expansion from one level of perforation of a hanging drilling injection pile is carried out in the following way: 1) An injector with a design diameter of 4 and a length of Й is made, with perforation at a depth determined by the project (Fig. 1, Fig. 2). The diameter of the injector d;,, must be smaller than the diameter of the well dev by 4-bsm. 2) Construct a well with a design diameter of 150-250 mm without fixing the walls of the well, if the stability of the soil allows, or with fixing the walls with stock pipes, if the conditions require it, to the design depth. 3) The injector is immersed in the well and centered with the help of centerers. 4) Cementation of the injector (Fig. 2) is carried out, that is, the annular space b (annular gap) is filled with a cement mixture, the composition of which is determined by the project. The cement mixture of the annular space must have the same composition as the cement mixture that will be used to create expansions. The stock pipes, if they 7/0 were applied, are pulled out.

The method of filling the annular gap is any that ensures high-quality filling.

Allow enough time to finish setting the cementing mixture in the annular gap. 7. With the help of a double tampon 7 (Fig. 3) (2), the perforation zone intended for the creation of cement expansion is isolated. 8. Destroy the cementing ring 6 by injection through a double tampon of cement mortar. The pressure of destruction of the cementing ring is not normalized and can reach 4-6 MPa. 9. After the destruction of the cement ring, injection of cement mortar continues with a flow rate of 6-12 l/min (0.1-0.2 l/s) until the design pressure is reached. This contributes to the creation of a cement ring 8 in the soil containing the well, which plays the role of cement spread and, after the approval of the cement mortar, contributes to increasing the load-bearing capacity of the pile. 10. Stop pumping, unfasten the double tampon and pull it out of the well. 11. Fill the internal capacity of the injector 9 (Fig. 7, Fig. 8) with cement mortar, which finally completes the construction of the pile.

The thickness of the cement expansion is determined by the well-known ratio (3):

IS

But not! sho de DP - amount of soil deformation under the action of injection pressure, m;

P - injection pressure, Pa;

E - module of general soil deformation, Pa; yu

AN - depth from the ground surface of the perforation zone.

The bearing capacity of the cement expansion is determined by the strength of the cut (break) of the cement expansion in contact with the cement of the injector clamp, which has a diameter equal to the diameter of the well. with

E eta Z losk AADN), F where t is the bending strength of the cement mixture. Pas; 5 - contact area, m; -

Oskv - the diameter of the well; dp - the thickness of the cement expansion, equal to the amount of soil deformation under the action of the injection pressure of the cement mixture through the perforation, m; "

E is the ultimate load that can withstand cement expansion from one perforation zone. Шо 70 When creating several extensions, the total bearing capacity is determined as the sum of the ultimate loads, which each extension can withstand.

From" References: 1. Building norms and rules SNIP 2.02.03-85. Foundation piles. 2. Construction norms and rules of SnyP 3.02.01-83. Foundations and foundations. -from 75 3. Tsitovych N.A. Soil mechanics (short course): Textbook for construction universities. - 4th ed., revised. and additional - M.: Viessh. Shk., 1983. - 288 p., illustrations. se) (ee)

Claims (1)

The formula of the invention Boro-injection hanging piles with cement expansion, which consist of a well and a cement mixture with which the well is filled (with or without a reinforced frame), which differ in that cement extensions are placed around the well. p. 60 b5