Research On Fluid-solid Coupling Damage Mechanism And Bearing Capacity Study Of High Strength Concrete Shaft Lining Under High Pressure Water

The deep coal strata of the Cretaceous-Jurassic series,which the freezing shaft crossing of whole bedrock in western China,was mostly argillaceous cemented filling calciiun fracture-pore double medium,showing characteristics of sponge type of water outlet.Its sandstone,conglomerate and sandy mudstone were characteristic of argillaceous cement,argillizatioii,mineralization,low strength and weathering,as well as poor pourability.Since the frozen bedrock shaft lining will suffer the underground high-water pressure for a long time after thawing of the frozen lining,,the damage of shaft lining and water gushing accidents occurred frequently.Exploring the mechanism and bearing capacity of the fluid-solid coupled damage of the shaft lining of the high strength concrete shaft in the frozen shaft,have important theoretical significance and the reference value to solving this question.Firstly,the damage evolution and microstructure change of high strength shaft lining concrete were observed through physical and mechanical parameters test,triaxial compression and seepage test.Based on a large number of experimental data,the damage variables were defined by using the circumscribed strain and the corresponding damage constitutive equation was proposed.The relationship between confining pressure,damage variable,principal stress difference,and concrete permeability was analyzed.The empirical formulas reflecting the permeability,confining pressure and damage of concrete were given by regression analysis in mathematical statistics.Secondly,based on the principle of effective stress,considering the concrete as a poroiis medium and introducing of the elastoplastic damage constitutive equation,combined with the application of unified yield theory and concrete strength criterion and considering the effect of groundwater seepage into account,shaft lining load analysis model under the direct action of 'high water pressure was established.Connecting with the constitutive damage relation of concrete and the relationship between permeability coefficient and damage,the analytic solution of freezing shaft lining liquid-solid coupled elastoplastic damage with external water pressure under high water pressure was deduced and tested.By using the analytical solution,the relationships between external water pressure and the radius of damage zone,pore water pressure and permeability,as well as the main influencing factors of shaft lining stress,damage evolution and bearing capacity of shaft lining were deeply analyzed,and the mechanism of liquid-solid coupled elastic-plastic damage of concrete frozen shaft lining under the action of high water pressure was revealed.Thirdly,the lining model experiment of raw material under the effect of high pressure water was carried out.Through the pore vater pressure sensor in the process of loading and acoustic emission equipment lining inside the generation of pore water pressure and internal damage monitoring,valuable experimental data obtained,and based on the results of shaft lining model test,the bearing mechanism of shaft lining under the direct action of high water pressure was deeply analyzed.Through the analysis of the results,the transfer of water pressure in the shaft lining was closely related to the stress state of the concrete of that.The change of the stress field of concrete changed the microstructure of the material,and then affected the permeability of the material,thus causing the change of the seepage field in the shaft lining.The seepage field in the shaft lining was always dynamically related to the stress field.Finally,through the finite elelent numerical analysis software COMSOL multi-physics,the coupling variables in the two fields were taken as parameter variables,and the darcy seepage field and the solid mechanical field in the software were selected respectively to solve the seepage field equation and the stress field equation.This paper was using the PDE module in the software and the custom variables method to realize the coupling of embedding,set up under the coupled action of seepage field and stress field of concrete constitutive model.Numerical simulation calculation tested with the similarity model test process,analyzed the change of the stress field and seepage field,and compared with the test results analysis,further proved under the coupled action of seepage and damage mechanism of vertical shaft lining bearing.Figure[51]Table[6]Reference[160]...