RU2622054C2 - Grout for compensation grouting in soils of bases while eliminating deformations of buildings and structures - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to the field of reconstruction of building structures, namely to eliminating their common deformations. The grout for compensation grouting into the base soils when eliminating deformations in buildings and structures contains, %: bentonite 60-80, Portland cement 10-30, a hardening accelerator up to 10, a plasticiser up to 2.

EFFECT: increasing the reliability of works on eliminating deformations in buildings and structures.

1 dwg, 1 ex

Description

The invention relates to the field of reconstruction of building structures, namely the elimination of their general deformations.

Known solution for compensatory injection into the soil of the grounds while eliminating the deformation of buildings and structures, containing a mixture of water and dry ingredients on a mineral basis. Portland cement in the solution contains 60%, fly ash - 38%, plasticizer 2% [Merkin V.E., Makovsky L.V., Pankina S.V. To the selection of a road tunnel in the Lefortovo area // Underground Space of the World, No. 4. - M., 1996. - S. 11-14].

The disadvantage of this solution is that cracks of indeterminate length and opening appear in the ground. These cracks require an increased flow rate of the mortar, may remain partially unfilled with the mortar, which in the future can lead to suffusion processes and reverse deformations of the structure.

Closest to the proposed one is a solution for compensatory injection of soils into the soil while eliminating deformations of buildings and structures, containing a mixture of water and dry mineral-based ingredients, including Portland cement. It has the following composition: Portland cement 50%, carbonate flour 49%, plasticizer 1% [Robert Mair Frend, David Harris, Innovative engineering to control Big Ben's titl // Ingenia (Royal Academy of Engineering) 9. 2001. Pp. 23 ... 27].

The advantage of this composition of the solution compared to the previous one is that the use of the solution significantly reduces the risk of cracking the soil, but the absence of hydraulic fracturing is not guaranteed. Cracking takes place, along with which there are the same dangers as in the previous technical solution.

The aim of the present invention is to reduce the cost of labor and materials and increase the reliability of work to eliminate the deformation of buildings and structures.

This goal is achieved in that the solution for compensatory injection of soils into the soil while eliminating deformations of buildings and structures contains a mixture of water and dry ingredients based on minerals, including Portland cement, and has the following composition:

- bentonite - 60-80%;

- Portland cement - 10-30%;

- hardening accelerator - up to 10%;

- plasticizer - up to 2%.

The essence of the invention is illustrated in the drawing, which shows a diagram of a technological complex to eliminate the deformation of buildings and structures (to explain the purpose and place of use of the solution).

The proposed solution for compensatory injection into the soil of the bases when eliminating deformations of buildings and structures is an aqueous suspension and has the following composition:

- bentonite - 60-80%;

- Portland cement - 10-30%;

- hardening accelerator - up to 10%;

- plasticizer - up to 2%.

Since the development of technology to eliminate the deformation of buildings and structures by injecting then a hardening solution then went in the direction of dividing the one-stage process into a two-stage process, corresponding requirements were made for each stage.

At the first stage, it was necessary to create an elastic matrix layer without changing the soil volume, but only by filling the pores with a highly permeable solution and thus obtain a single elastic material. It should be noted that the injection of the solution is subject to strict rules that ensure the pressure and flow rate.

At the second stage, when injecting a poorly permeable solution, an expandable layer is created with a change in its volume, which is able to resist rupture, when the injection process becomes uncertain due to the presence of cracks into which the solution escapes.

This technical solution is a solution for injection in the second stage, i.e. is a solution that is characterized by low permeability and ability, when combined with the soil, to create a composite material with the required properties.

The main requirement for the solution at the stage of compensatory injection is determined by the ability to provide pressure as distributed as possible over the area in order to reduce the concentration of the effect on the layer matrix and eliminate the risk of its rupture. To ensure this requirement, the proposed solution for compensatory injection is gaining strength gradually. During the first day the solution remains liquid, within 5-10 days the solution has a gel consistency, after 10 days the solution hardens. Due to the slow hardening, the solution penetrates into the pores, is evenly distributed in the soil and also increases uniformly in volume without cracking. The injection of the solution is carried out with strict observance of the parameters of pressure and flow.

The essence of the process where the proposed solution is used is as follows.

To eliminate the deformations of the foundations of buildings, several tiers of channels 1 for mortar injectors are arranged under the foundation of the building, which are located under the foundation 2 of the building, injectors 3 of the solution placed in channels 1, expandable layers 4 and matrix layers 5. Layers 4 and 5 are a mixture of local soil with injected solution. Injectors 3 of the solution through channels 7 arranged in the shaft 6 are connected to a pumping station 8 for supplying a solution, and through channels 9 are connected to a compressor 10 for supplying compressed air.

Elimination of deformation of the foundations of buildings is as follows. First, a matrix layer 5 is formed using the injector 3 by injection at a pressure of not more than 5 atm of a highly permeable solution. As a result, the pores of the soil are filled, and the skeleton of the soil is not broken. This soil can absorb pressure and move further under pressure in the process of compensatory pumping, helping to raise the foundation.

The expandable layer 4 is formed already during the period of the foundation’s immediate rise in the process of compensatory injection due to the injection of a poorly permeable solution under high pressure (20-50 atm). As a result, the soil is mixed with the solution, the total volume of the layer increases, the layer 5 moves and the foundation rises. The formation of an expandable layer can go in several stages to obtain the required accuracy of alignment of buildings or structures.

With preliminary injection (i.e., creating a matrix layer), the best effect is achieved by injection from the upper tier downward, while the reinforced zone is immediately limited from above, where cracks and tears are possible. After this, with further injection into the lower tiers, the process proceeds more favorably in them.

In compensatory injection, the expandable layer expands up and down. To increase efficiency, injection begins from the lower tier (see drawing). and then continue according to the “bottom up” principle, therefore, the total upward strain “δ _in ” (which is equal to the strain “δ _s ” of the building) is greater than the total strain “δ _n ” down.

When prescribing the composition of the solution for compensatory injection, compliance with the condition of industrial applicability should be observed: when striving for the maximum amount of one of the components, the total number of components should be equal to 100%.

An example of execution of the invention.

When a Moscow metro branch was drilled, deformation of a 6-story building on Dmitrovskoye Shosse occurred. The amount of precipitation was 95 mm. It was decided to apply compensation injection technology. This technology involved the creation of a matrix layer at the first stage by preliminary injection of a highly permeable solution into the soil, and then at the second stage, the implementation of compensatory injection of a low permeability solution.

Pre-injection was carried out by impregnating the soil with a highly permeable aqueous suspension based on finely ground microcement with the following composition: Microdur microcement - 35%, colloidal silica 10%, hydrated lime Ca (OH) ₂ - 15%, carbonate flour - 35%, superplasticizer C -3 - 2%, methyl cellulose - 3%. The injection was carried out through cuff injectors with a pressure of P _{1 current.} = 4 atm. and flow rate Q _{1 current.} = 4.5 l / min. The end of the injection was completed at the moment when the flow rate decreased to Q _{1, min} = 1 l / min, at a pressure of P _{1, max} = 5.5 atm.

Then, compensation injection was performed by a poorly permeable solution based on bentonite activated by mechanochemical treatment, the solution having the following composition: bentonite - 70%, Portland cement 20%, plasticizer 1%, hardening accelerator 9%. The injection was stopped when the total sediment decreased to 2 mm, and the pressure P _{2, max} was 26 atm.

The characteristics contained in the general concepts of “plasticizer” and “hardening accelerator”, covering various particular forms of its implementation, provide, in combination with other signs, the technical result indicated by the applicant for such particular forms of implementation: 1) plasticizers: S-3, superplasticizer; Sika-Mix Plus; BV-3m; Plastimix; Mapei-Planicrete; 2) hardening accelerators: Ceresit-C; CemFix; Polyplast-1 MB; Fort-UP-2; Hydrotex-PMD.

The effectiveness of this technical solution is to reduce labor costs and materials while increasing the reliability of the fixed base of buildings and structures by eliminating cracking and hydraulic fracturing of the soil.

Claims (2)

A solution for compensatory injection of soils into the soil while eliminating deformations of buildings and structures, containing a mixture of water and dry mineral-based ingredients, including Portland cement, characterized in that the solution contains,%: bentonite 60 - 80 Portland cement 10-30 hardening accelerator to 10 plasticizer up to 2

Images