Study On Shaft Lining Structure Of Hybrid Fiber Reinforced Concrete Under Uneven Freezing Pressure In Deep Clay Layer

In Deep Alluvium Freezing drilling,due to the deflection of freezing hole and uneven distribution of salt water flow,the freezing pressure on the outer wall of freezing shaft presents non-uniform characteristics,especially in deep clay layer,which worsens the stress condition of outer wall and easily leads to accidents such as tensile damage,which seriously threatens the safety of shaft construction.Therefore,in order to improve the ability of the outer wall to resist the uneven freezing pressure,this paper proposes to use the hybrid fiber concrete as the wall building material,and carries out the research on the hybrid fiber concrete shaft lining.structure under the action of the uneven freezing pressure in the deep clay layer.First of all,according to the analysis of the failure of the outer wall of the freezing section of the East return air shaft in Huainan Guqiao Coal Mine during the construction of deep clay layer and the measured freezing pressure,it shows that the non-uniformity of the freezing pressure on the outer wall is obvious,which is the main reason for the failure of the outer wall;and through the analysis of the measured data of the freezing pressure on the outer wall of the deep clay layer in Lianghuai mining area,it shows that the non-uniformity of the freezing pressure is relatively small In order to prevent the damage of outer wall,the tensile property of concrete should be improved.Secondly,according to the stress mechanism of freezing shaft outer wall in deep clay layer,hybrid fiber concrete is selected as wall building material to improve the ability of outer wall to bear uneven freezing pressure.Through the orthogonal test method,the optimal mix proportion of shaft wall hybrid fiber concrete is obtained,and the mechanical properties such as compression,tensile,flexural and axial compression tests and microstructure analysis are carried out.The results show that the hybrid fiber can improve the compressive strength of concrete by 44.85%and 31.34%respectively,and can enhance the ductility and improve the internal structure of concrete.Meanwhile,The results show that the hybrid fiber can improve the impermeability,freeze-thaw resistance and sulfate corrosion resistance of concrete,and can meet the durability requirements of shaft lining concrete.Then,considering the influence of thickness diameter ratio,the ANSYS software is used to simulate the new type of outer wall structure,and the stress distribution characteristics of the outer wall are obtained when the non-uniform pressure coefficient is 0.1,0.2 and 0.3 respectively,and the calculation formula of the bearing capacity of the shaft lining is regressed.Finally,the stress and deformation characteristics of the new type of shaft lining structure are obtained by the similar model loading test under the action of uneven load.The ultimate bearing capacity of the shaft lining under 0.2 uneven pressure coefficient is 6.5MPa for small load and 7.8mpa for large load,which is in good agreement with the numerical simulation results.The research results show that the hybrid fiber can significantly improve the tensile strength of shaft lining concrete,meet the durability requirements of shaft lining,improve the brittle failure characteristics of concrete,and improve the reliability of shaft lining structure.It is an excellent material for shaft lining structure under uneven freezing pressure in deep clay layer.Figure 51 table 24 reference 84...