Study On Pressure Relief Effect Of Rubber Concrete Used In Soft Rock Tunnel With High Geostress

In view of the problems of high stress and low strength of soft rock under high geostress,rubber concrete with low density,good toughness and strong crack resistance is applied in soft rock tunnel under high geostress to achieve the purpose of pressure relief in high geostress soft rock tunnel.Six factors,including rubber particle size,rubber content,accelerator content,water cement ratio,sand ratio and shotcrete,are selected to carry out orthogonal numerical simulation tests with six factors and three levels to analyze rubber coagulation.The aim of the test is to analyze the sensitivity of rubber concrete to the effect of pressure relief in high geostress soft rock.The main research contents are as follows:?1?Through orthogonal design experiments,the compressive strength,modulus of elasticity and Poisson's ratio of various groups of rubber concrete are studied.It is found that rubber content is the most important factor for the compressive strength,modulus of elasticity and Poisson's ratio of rubber concrete.Water cement ratio and rubber particle size are the main factors for rubber concrete,while the influence of accelerator content and sand ratio is relatively weak.?2?The orthogonal numerical simulation experiment is carried out by FLAC^3D to study the influence of various factors on the stress of secondary lining structure,stress release rate of surrounding rock and displacement of surrounding rock.The results show that the increase of displacement of surrounding rock,the increase of stress release rate of surrounding rock and the decrease of stress of secondary lining structure are matched.Among all the factors,the rubber content,water cement ratio and rubber particle size are the most important factors affecting the pressure relief of rubber concrete.?3?By applying the optimum scheme of orthogonal test to the surrounding rock of soft rock tunnel with high in-situ stress between the initial support,it is found that the displacement and stress of surrounding rock basically tend to be stable before and after the secondary lining,which shows that rubber concrete with low density and good toughness can make the surrounding rock fully deformed,release the stress of surrounding rock and reduce the support pressure.?4?Based on the uniaxial compressive strength and modulus of elasticity of rubber concrete,the unloading effect of rubber concrete applied in soft rock tunnel with high geostress is studied.With the increase of uniaxial compressive strength of rubber concrete,the stress of secondary lining structure increases,the stress release rate of surrounding rock decreases,and the displacement of surrounding rock decreases.With the increase of elastic modulus of rubber concrete,the stress of secondary lining structure increases,and the stress of surrounding rock decreases.The release rate decreases and the displacement of surrounding rock decreases.There are 38 figures,26 tables and 63 references in this thesis.