Experimental Study On The Sandy Mudstone Mechanical Properties For Frozen Shaft Wall In Deep Thick Water-Rich Bedrocks

In recent years, more and more vertical shafts have subjected to deep alluviums and deep soft rocks layers, water-rich soft rock layers, low strength, the rocks were unstable. In order to improve the strength and ensure surrounding rock stability, freezing construction is proposed. So it is of theoretical research value and practical significance to carry out the tests of the artificial freezing soft rock and to study its physical-mechanical characteristics.In this paper, with the background of shaft freezing project in Hujiahe coal mine in Shanxi Bingchang mining area, under the basis of sandstone and coal-rock which were studied by the studying team of the same engineering background and the same test conditions, sandy mudstone were obtained from the engineering site, the uniaxial compression tests were conducted systematically at different frozen temperatures considering the frozen temperature range of the site. The strength and deformation characteristics of sandy mudstone under different frozen temperatures, the different strength and deformation characteristics of different stones under the same frozen temperatures, the damage characteristics and the elastic modulus under frozen temperatures were analyzed. Triaxial compression tests were conducted according to the sandy mudstone's actual formation depth, from the same temperatures under the condition of different confining pressures and the same confining pressure under the conditions of different temperatures to the strength and deformation characteristics of sandy mudstone and sandstone, coal-rock were comparatively analyzed and compared with the uniaxial compression tests. Based on this analysis, we have studied the size and the change rule of sandy mudstone and sandstone, coal-rock in the maximum value of axial strains, the elasticity coefficient, the Poisson ratio, the limit of compressive strength, the residual strength, the cohesive force and friction angle under the different confining pressure and temperature conditions. From the statistical characteristics of rock strength, the rock elastoplastic damage constitutive model was established with the introducing of rock stress~strain curve characteristic parameters and the considering of rock stress~strain curve extreme conditions.