RU2209267C1 - Process of earth fixing - Google Patents

Abstract

FIELD: construction industry. SUBSTANCE: invention is related to processes fixing earth in foundations of buildings and structures, it can be employed for formation of pile foundations of structures of various assignment in soft water-saturated soils. Process of earth fixing includes determination of number, sequence of bedding, thickness and properties of geological elements in geological section of fixed mass of earth with subsequent earth fixing by means of individual stopes from beneath upwards over height of fixed earth. Novelty of approach lies in that cast-in-place piles with use of casing are erected by way of complete replacement of earth with concrete mixture in geological elements with largest subsidence properties, in all other elements earth-and-cement cast-in-place piles are erected according to flow technology. Each stope is executed after pile erected by preceding stope acquires strength sufficient to keep earth fixed in the course of next stope. Cast-in-place and earth-and-cement cast-in-place piles are erected uniaxially. EFFECT: enhanced degree of fixing and bearing capability of earth with reduction of construction time and usage of concrete.

Description

 The invention relates to the field of construction, and in particular to methods of fixing the soils of the foundations of buildings and structures, and can be used in the formation of pile foundations of structures for various purposes in weak, saturated soils.

 In the process of construction of pile foundations of structures for various purposes in weak water-saturated soils, it becomes necessary to fix these soils. Soils in the geological section may contain geological elements heterogeneous in their properties (soil layers), including problematic ones (underground cavities, water lenses, dense clay). The number and alternation of such geological elements can be very diverse.

 A known method of strengthening soils, in particular weak water-saturated, according to which a sealing solution is introduced into the base of buildings and structures through a system of injectors, using a sand-cement mixture. A cement-cement bearing element is formed with the formation of a rigid skeleton directly in the soil mass with an increased bearing ability in the form of a natural technological composite / RF Patent 2059044, E 02 D 3/12, 1996 /.

 The disadvantage of this method is the limitation of the possibility of its use for fixing soils with problematic geological elements - voids. water lenses, thick clay, etc.

 A known method of fixing soil with an underground cavity, including the formation of vertical wells before connecting them to the underground cavity and injection into the cavity of the fixing material, the formation of wells is carried out in rows, then in the plane of each row are drilled to a depth greater than the location of the bottom of the cavity, inclined, intersecting additional wells above the cavity, and the fixing material is injected into the cavity by alternately supplying saturated steam and dry cement-bentonite mixture / Auto USSR certificate of the USSR 787550, E 02 D 3/12, 1980 /.

The disadvantages of this method are the high complexity, material consumption and energy intensity
The closest in technical essence to the proposed is a method of fixing the soil, including the formation of wells and injection into them of cement or soil-cement mortar from bottom to top of the hole in separate runs, determining the number, bedding order, thickness and properties of geological elements in the geological section of the fixed mass of soil and use for each geological element of its solution, the cement consumption for which is determined by the calculation formula / Patent RF 2133795, E 02 D 3/12, 1999 /.

 The disadvantages of this method is that when drilling wells in weak soils, the walls of the wells are unstable, especially if there are voids or water lenses among the soil layers, and the subsequent injection of the fixing solution into such wells will create uneven bearing capacity of the fixed soil mass in height.

 The present invention is the construction of pile foundations of structures for various purposes from fixed soils.

 The technical result from the use of the proposed method is to increase the degree of consolidation and bearing capacity of the soil while reducing construction time and reducing concrete consumption.

 The problem is solved, and the technical result is achieved due to the fact that in the method of fixing the soil, which includes determining the quantity, bedding order, thickness and properties of geological elements in the geological section of the fixed mass of soil with subsequent fixing of the soil with individual entries from bottom to top in the height of the fixed soil, geological elements with the greatest subsidence properties erect bored piles using casing by completely replacing the soil with concrete mixture, and other geological elements erecting piles of jet-grouting technology, with each subsequent stope performed after the pile erected previous stope, attains sufficient strength to hold the subsequent fastened stope ground and drilled and grouting of the pile erected coaxially.

 The method is as follows.

 On the site allotted for the construction of a new structure, engineering and geological work is carried out with the determination of the quantity, order of occurrence of the thickness and properties of geological elements in the geological section of the soil mass. In the event that the presence of a geological element with the greatest subsidence properties is found among the soil layers, a bored pile is constructed in it using a casing pipe by completely replacing the soil with a concrete mixture, and in other geological elements, cement-cement piles are built using jet technology. Depending on the order of occurrence of the soil layers in the geological section, alternation of the various stages of soil consolidation (making calls) takes place - by jet technology or by the construction of a bored pile. Each subsequent approach is carried out after the pile, erected by the previous find, gains strength sufficient to hold the soil fixed during the next call. Bored and cement piles are erected coaxially.

Example 1
Geological surveys of the soil under the site planned for construction showed the presence in the soft-plastic loam of soil leaching at a depth of 5.3 m from the surface, 0.6 m thick, located at a height of 4.2 m from the bedrock. The first entry to fix the soil of soft plastic loam - using a one-component jet technology, a cement pile is built based on root soil with a diameter of 1 m and a length of 4 m. On the second day after the construction of a cement cement pile, a second entry is started: into the soil with support on a cement-cement pile, a casing pipe with a diameter of 0.86 m is placed with it, inside and on the bottom of which a screw is placed, during the lifting of which they remove the problem soil at the same time as it is completely replaced with a concrete mix pumped under the heel of the screw b, to a length of 0.9 m / The casing and screw are removed from the ground. 24 hours after the construction of the bored pile in the course of the subsequent third run, a cement-cement pile is erected coaxially using a single-component jet technology. Joint hardening of soil-cement and bored piles can improve the quality and bearing capacity of piles erected from fixed soil, including due to additional friction forces (due to partial interpenetration of soil-cement and concrete).

Example 2
Geological surveys of soil under the site planned for construction showed the presence of a cavity above the bedrock at a depth of 9.6 m, a height of 0.85 m, as well as layers of weak fluid-plastic loam. A casing pipe with a diameter of 1.3 m with a support on the ground soil is placed as the first approach to fix the soil, a screw is placed inside and on the bottom of the screw, during the lifting of which they remove the problematic soil at the same time as it is completely replaced with concrete mix pumped under the heel of the screw, for a length of 1 , 0 m. The casing and screw are removed. 12 hours after the completion of the injection of the concrete mixture in the course of the subsequent second approach, a cement-cement pile is erected coaxially with a one-component jet technology with a diameter of 1 m, a length of 8.6 m. Joint hardening of cement-cement and bored piles can improve the quality and load-bearing capacity of piles constructed from the fixed soil , including due to additional friction forces (due to partial interpenetration of soil cement and concrete), as well as significantly (by 80%) saving concrete consumption for due to the strengthening of the soil by jet technology, instead of constructing a continuous bored pile 9.6 m long.

 Thus, the proposed method of fixing the soil allows to increase the degree of consolidation and the bearing capacity of the soil. The use of soil fixed by the proposed method as a base, for example, a tunnel, can significantly (up to 40%) reduce concrete consumption for the erection of load-bearing structures of a newly constructed structure and reduce construction time.

Claims (1)

 A method of fixing the soil, including determining the number, bedding order, thickness and properties of geological elements in the geological section of the fixed mass of soil with subsequent fixing of the soil with individual penetrations from bottom to top along the height of the fixed soil, characterized in that bored piles are erected in geological elements with the greatest subsidence properties using casing by completely replacing the soil with concrete mixture, and in the remaining geological elements erected cement-cement sv and ink jet technology, with each subsequent stope performed after the pile erected previous stope, attains sufficient strength to hold the subsequent fastened stope ground and drilled and grouting of the pile erected coaxially.