Study on the change of physical properties of sandstone under action of acidic drying-wetting cycles and discrete element simulation

This study investigated the changes in the physical parameters of sandstone (solution pH, mass, P-wave velocity, and porosity) and mechanical strength (tensile strength) under acidic drying-wetting cycles. Additionally, the particle flow code (PFC) was used to simulate the drying-wetting cycles. The results reveal that the pH range of the acidic solution is much larger than that of the neutral solution. The changes of the mass and P-wave velocity are consistent and both exhibit a decreasing trend, which slowed down in stage IV. Compared with the neutral solution, the acidic solution could accelerate the damage peak of the specimen and cause early destruction. The S curve variation of porosity indicates that the decrease of physical parameters in stage IV was caused by the slowdown of porosity growth. In turn, this indicates that the soluble material in the specimen decreased, and the number of drying-wetting cycles could not excite new crack generation, which resulted in the slowdown of the loss rate. The results obtained by the Brazilian splitting test (BTS) reveal that the damage in the acidic solution of the specimen first deformed by compression and then by splitting damage, which is different to the direct splitting damage in the neutral solution. The simulation also proves that the specimen mainly exhibited extrusion deformation in the y-direction and tensile damage in the x-direction. The contact between the particles inside the specimen gradually decreased as the cycles progressed. Finally, damage occurred under low pressure.

Automated summary

This study investigated the changes in physical parameters and mechanical strength of sandstone under acidic drying-wetting cycles. Results showed that the acidic solution caused more severe damage to the specimens and led to early destruction, while the slowdown in porosity growth contributed to the gradual decrease in physical parameters.