The research methods of macro and micro rock mechanics have developed rapidly with the in-depth study of rock mechanics. However, there is a lack of research on the influence of rock microscopic property changes on causing the macroscopic mechanical anisotropic behavior of rock masses. In discrete element analysis methods, the accurate characterization of the macroscopic mechanical behavior of rock masses requires not only reasonable fine-scale parameters but also the composition and content of microscopic minerals in rocks. Thin section specimens of limestone were made to determine the mineral composition and content polarized light microscope. Mineral content-based discrete element models were established, and the microscopic mechanical behaviors among minerals were simulated with the contact softening model. The uniaxial compression and the Brazilian splitting models corresponding to the indoor tests were established. The microscopic strength parameters were adjusted using the trial-and-error method to make the macroscopic mechanical properties of the microscopic model consistent with the actual situation. The results show that the macroscopic parameters obtained from the numerical simulations are consistent with the results of the indoor tests, indicating that the parameter calibration method of the discrete element model based on the microscopic mineral content of the rock mass can well calibrate the meso-scale parameters of the particles. The meso-scale strength parameters can well characterize the macroscopic mechanical strength of the rock mass, which can be used as the input parameters for the mechanical response analysis of the rock mass to understand the mechanical behavior of the rock mass more accurately.

The special stratum lithology, hydrogeology and climatic conditions in Guizhou area make most of the collapse disasters in this area have a close relationship with dissolution. Taking the collapse of Huishui Xinzhai Village in Guizhou Province as an example, the thick and thin carbonate rocks of collapsed bodies is studied, the chemical composition, microstructure of the rock and the influence of different PH values of acidic solution on the dissolution are analyzed, and the PCAS software is used to perform statistical analysis on the voids on the surface of the rock sample after dissolution. The study results show that: The chemical composition and microstructure of rocks both control the differential dissolution of rocks. The dissolution of thin-layer pure limestone is obviously stronger than that of thick-layer dolomitic limestone. The dissolution starts from the intergranular pores, structures and cleavages of rocks, and gradually expands, making the pores and fractures connected with each other. The dissolution of rocks becomes more severe with the decrease of the pH value of the solution. The pore area and the number of pores on the surface of the thick limestone after dissolution are inversely proportional to the pH value of the acid solution, while the pore area and the number of pores on the surface of the thin limestone after the dissolution are directly proportional to the pH value of the acid solution.