Study on the Microscopic Mechanism of Differential Dissolution of Carbonate Rocks in Guizhou Area

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.