Damage Analysis of Chemically Corroded Sandstone Under Cyclic Impacts and Axial Static Pressure

To explore the influence of cyclic impact and axial static pressure on the damage of chemically corroded sandstone, a series of cyclic impact tests were conducted on white sandstone by using the Split Hopkinson Pressure Bar. Besides, the longitudinal sections and fractures of samples were observed with the scanning electron microscope for the purpose of investigating the damage characteristics and structural changes of sandstone subjected to the coupling of force and chemistry. The results show: (1) When pH of the solution is 7, the number of cyclic impacts and stress peaks of specimens increases, and the specimens respond with a significantly high resistant strength. (2) The stress wave transmission coefficient of sandstone decreases gradually with the increase of the number of cyclic impacts, while the reflection coefficient shows a tendency of "decreasing firstly and then increasing". (3) Cylindrical specimens with a certain axial static pressure present an "X" shaped conjugate failure under cyclic impact. When axial static pressure is too large or there is excessive impact, the "X" shaped conjugate undergoes shear to a state of broken cones. (4) The vertical section and fracture surface damage degree of white sandstone soaked in the sodium sulfate solution is more serious than that in the sodium sulfate solution.