Study On Mechanism Of Lifting And Reinforcement Effect Of Soil And Preventing Shaft Lining Fracture By Grouting

The shaft is a key throat part for transporting coal,personnel,materials and equipment as well as ventilation and drainage during the production of a mine.The construction and maintenance of shaft is crucial to ensure the safe production and operation of coal mine.During coal mine production,the shaft is affected by drainage of thick topsoil for a long time,the external surface of the shaft lining will produce vertical downward additional force,resulting in the fracture of the shaft lining,which affects the safety and stability By grouting to the stratum,the surrounding soil layer can be raised and strengthened,so as to prevent the fracture of the shaft lining.However,the theory of grouting uplift and reinforcement lags behind the engineering practice,and there is a lack of supporting grouting reinforcement theory and research results for buildings such as the shaft traversing thick alluvium.Firstly,this thesis summarizes the current research status of grouting lifting and strengthen soil and preventing buildings from cracking from four aspects:theoretical research,laboratory model test,numerical simulation and in-situ test.Then,through model test and numerical simulation to explore the effect of grouting on soil lifting and reinforcement.In addition,the parameter of grouting pressure is innovatively introduced to comprehensively evaluate and analyze the effect of preventing shaft lining fracture,the aim is to enrich the theory of grouting reinforcement and provide reference for the implementation of similar grouting projects.The main research results are as follows:（1）Based on the screening test,liquid-plastic limit test,direct shear test and compression test,the relevant physical and mechanical indexes of the test soil are obtained,which laid the foundation for the comparative analysis of the soil reinforced by grouting test.Then,through gel test and uniaxial compression test,the influence of water-cement ratio,sodium silicate concentration and volume ratio on the performance of cement-sodium silicate double liquid slurry is analyzed,which provides parameters for the finite element simulation of grouting prevention and control of shaft lining fracture,and also provides parameter guidance for actual grouting engineering.（2）Based on the independent research and development of grouting model device,experiments of grouting lifting and strengthening soil are carried out,and the influence of different grouting pressure and water-cement ratio factors on soil lifting and strengthening is analyzed.The results show that the lifting displacement curve of soil surface is unimodal and distributed symmetrically along the grouting point.In addition,the shear index and compression modulus of the soil at different depths after grouting are measured.According to the test results,the shear strength of the soil at different depths after grouting is effectively improved.The shear strength of the soil closest to the grouting hole increases the most.With the increase of the width of the grouting veins in the ring tool sample,the cohesive force c of the soil has an overall increasing trend,while the internal friction Anglehas a stable growth trend.In addition,the compressive modulus of the soil near the grouting hole can be significantly improved,and the maximum compressive modulus of the soil near the grouting hole is 3 times that of the ungrouting soil.（3）According to the mechanical parameters measured in laboratory tests,the lifting effect of soil mass under different grouting pressure and water-cement ratio is simulated by using FLAC^3D,the result shows that the uplift trend of model test and numerical simulation is basically the same,and the uplift curves of split grouting and ideal compaction grouting meet the Gaussian function distribution.The difference is that the uplift center will change due to the grouting form.（4）FLAC^3D is used to carry out the numerical simulation of grouting for the prevention of shaft lining fracture.Based on the elastic-plastic theory,the grouting reinforcement range is connected with the grouting pressure,and the grouting reinforcement area is divided into slurry stone area and soil reinforcement area.The distribution characteristics of shaft lining stress displacement under the comprehensive action of grouting parameters（grouting pressure,reinforcement distance,reinforcement range）are studied.The result shows that there is an optimal grouting distance in the central aquifer to prevent shaft lining breakage.This conclusion accords with the concept of"optimal reinforcement distance"proposed by Professor Zhou Guoqing,and can provide reference for the implementation and research of similar projects in the future.There are 110 figures,30 tables and 86 references in this thesis.