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

To explore the influence of cyclic impact and axial pressure on the damage of chemically corroded sandstone, a series of cyclic impact tests were carried out on white sandstone by using Split Hopkinson Pressure Bar. The longitudinal sections and fractures of samples were observed with the scanning electron microscope. The aim was to investigate the damage characteristics and structural changes of sandstone, that subjected to the coupling of force and chemistry. The results show that: (1) When pH of solution is 7, the total cyclic impact number and stress peak of specimens both became larger, and the rock samples responded 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 first and then increasing". (3) Cylindrical specimens with a certain axial pressure present an "X" shaped conjugate failure under cyclic impact. When axial pressure is too large or excessive impact, the "X" shaped conjugate undergoes shear to a state of broken cone. (4) The vertical section and fracture surface damage degree of white sandstone soaked in Na2SO4 solution is more serious than that in NaCl solution.