Study on mechanical model of layered limestone under dissolution
[Objective]Different layers of layered limestone show different mechanical properties.In order to study the influence law of mechanical properties of layered limestone with different dip angles under dissolution,a transverse isotropic strain softening model under dissolution is established to describe the mechanical properties of layered limestone under dissolution.[Methods]Firstly,the transverse isotropic strain softening model is used to describe the mechanical properties of parallel and vertical bedding planes of layered limestone without corrosion.Combined with the analysis of the uniaxial compression test result of layered limestone with four bedding angles of 0°,30°,60° and 90°,the core parameters(elastic modulus,cohesion and internal friction angle)of parallel and vertical bedding planes of layered limestone without corrosion are obtained.Then,based on the analysis of the mechanism of mechanical change of layered limestone under dissolution,the plastic mechanical model of layered limestone under dissolution is determined.Finally,combined with the uniaxial compression mechanical test result of layered limestone under dissolution,the FLAC-strength reduction method was used to determine the variation of mechanical parameters(elastic modulus and cohesion)with dissolution in the mechanical model of layered limestone under dissolution.[Results]The result show that the dissolution equivalent time and unloading strain(unloading strain at crack development degree)have differ-ent effects on the mechanical properties of layered limestone with different dip angles.The dissolution equivalent time has the greatest influence on the parameters of layered limestone with a dip angle of 0°,and the unloading strain has the greatest influ-ence on the parameters of layered limestone with a dip angle of 30°.The effect of dissolution equivalent time on matrix cohesion c2 is greater than that of layer cohesion c1,and the effect of unloading strain on c1 is greater than that on c2.[Conclusion]The transversely isotropic strain softening model can accurately obtain the relationship between the mechanical strength parameters of different dip angles of layered limestone and dissolution,and better characterize the mechanical properties of layered limestone with different dip angles under dissolution,which can provide a theoretical basis for the stability analysis of surrounding rock of karst underground caverns.
万方数据
维普
