Experimental Study on Sandstone Freezing-thawing Damage Properties under Condition of Water Chemistry

摘要

For the purpose of researching the freezing-thawing cycle pHysical mechanics properties of sandstone in various chemical solutions, taking the red sandstones from Shandong as the example, freezing-thawing cycles experiments under the condition of H_2SO_4 solution (pH≈1.5), NaOH solution(pH≈12.5), NaCl solution (pH≈7, mass fraction is 4%) and water were conducted. The nuclear magnetic resonance (NMR) technique was used to test the porosity of rock samples after freezing-thawing cycles. Brazilian splitting test was also conducted to test the samples with different times of freezing-thawing cycles and soaking solutions. Results show that the quality change of samples in various solutions is different. The mass of sample in water increased, however, the mass change of the sample in other three solutions showed a firstly increasing and then decreasing tendency. The porosity distribution in rock changed obviously after different time's freezing-thawing cycles. After 30 times freezing-thawing cycles, the porosity in H_2SO_4 solution, NaOH solution, NaCl solution and water has increased by 151.1%, 85.443%, 39.388%, and 17.976% respectively. With the increase of freezing-thawing cycle's times, tensile strength of the rock reduced, but the damage properties were different in various solutions. The research can provide some mechanical parameters basis to physical mechanics properties of sandstones.