Study Of Mechanical Properties Experiment And Damage Constitutive Model For Coal-Serial Sandy Mudstone Under Different Temperatures

In this paper, with the background of coal-serial sandy mudstone for the first time, laboratory tests were made to study the mechanical properties of uniaxial and triaxial compression tests for coal-serial sandy mudstone from25℃to55℃by using the RMT-150B rock mechanics test system and GD—-65/150high and low temperature environmental chamber. The effects of complete stress-strain curve, peak stress, peak strain, elastic modulus and deformation modulus of sandy mudstone at different temperatures were analyzed. Temperature on the mechanism of action and deformation mechanism of sandy mudstone is revealed, and a statistieal constitutive model for rock damage considering temperature effeet is established. Combined with testing process, theoretical models is detected and corrected by numerical simulation. The results have important theoretical significance and practical value for the implementation of deep coal mining safely and efficiently and the prediction and control in the disaster of deep soft rock engineering. The main research results and conclusions are listed as follows:(1) The variation of stress-strain curve for sandy mudstone under uniaxial compressive stress at different temperatures generally has gone through four stages, namely compaction stage, linear elastic stage, plastic yielding stage and failure stage. There is difference of mechanical properties between at different temperatures. As the temperature increases, peak stress and peak strain decrease gradually. Elastic modulus decreases linearly with the increasing temperature. Deformation modulus increases linearly with the increasing temperature. Poisson’s ratios gets larger at first but then smaller with the increasing temperature; there is a peak point at40℃and the law changes significantly.(2) The variation of stress-strain curve for sandy mudstone under triaxial compressive stress at different temperatures generally has gone through four stages, namely compaction stage, linear elastic stage, plastic yielding stage and failure stage. In the role of confining pressure, because the specimen occurs lateral compaction, so compaction stage of the specimen is shorter. As the temperature increases, peak stress decrease gradually; peak strain increases before45℃and decrease after45℃; elastic modulus decreases before45℃and increase after45℃; deformation modulus get smaller at first but then larger with the increasing temperature.(3) Based on the random statistical distribution hypothesis of rock strength and the strain strength theory, applied mechanical parameters extreme value of stress-strain curves obtained, a statistical constitutive model for rock damage considering temperature effeet is established..Accordingly, the stress-strain curves of rock under different temperature(before55℃) can be caleulated by the stress-strain curve of rock under normal temperature.