Study On Deterioration Law Of Physical And Mechanical Properties Of Sandstone Under Coupling Action Of Acid-base Erosion And Dry Wet Cycle

In the process of deep mining,groundwater threatens the safety and stability of deep engineering all the time.The long-term effect of water on deep rock mass will change its physical and chemical properties,resulting in many hazards to deep engineering,such as roadway floor heave,surrounding rock deformation,roof falling and so on.In addition,in the process of long-term dissolution of minerals,groundwater often presents weak acidity or weak alkalinity,and the performance degradation of rocks will be further deepened under the dual action of water dissolution and chemical corrosion.In this paper,the rock produced during the construction of the return air roadway in Zhangji mine in Huainan mining area is taken as the test object,and the acid-base erosion and dry wet cycle treatment with different concentrations are carried out to study the variation law of various physical and mechanical parameters,microstructure evolution law and damage mechanism.The main research contents and results are as follows:Research content:The specimens were subjected to solution erosion with pH of 3,7 and 11 and 0,7,14 and 21 dry wet cycles.At each stage of the test,the pH value of the solution,the longitudinal wave velocity of sandstone,the drying quality and saturation quality of sandstone were measured,the porosity of sandstone was calculated,and various physical parameters were analyzed;Uniaxial compression test,Brazilian splitting test and dynamic splitting test were carried out on the treated sandstone,and the deterioration laws of various mechanical properties were analyzed and summarized.Research findings:Under the coupling action of acid-base erosion and dry wet cycle,various physical and mechanical indexes of sandstone specimens deteriorate to varying degrees.Among them,the changes of solution pH value,sandstone longitudinal wave velocity,sandstone quality and porosity show a fast slow fast trend in the whole test process.It is known from the XRD diffraction patterns of sandstone specimens before and after treatment that during the test process,H+and OH+ in the acid-base solution will react with the components in the sandstone,and the products will stay in the pores,hindering the contact between the chemical solution and the sandstone to a certain extent until the later stage of the test;The retained products affect the uniaxial compressive properties of the specimens to a certain extent,but the tensile properties and dynamic tensile properties are not affected,which are deteriorating with the progress of the test.Figure[44];Table[15];Reference[69]...