Shear Strength Characteristics of Kimachi Sandstone in an Environment with Ultralow Temperatures

The practical application of the rock cavern storage of liquefied fuels (such as natural gas, liquid hydrogen or dimethyl ether) requires stability analysis of the cavern in question with regard to thermal stress; and an understanding of strength parameters (cohesion and angle of internal friction) of rock mass is essential for such analysis.In our research, we conducted an oblique shear test to dice for determining the strength parameters with sandstone from room temperature down to ultralow temperatures. Next, we attempted a method for estimating the strength parameters from the results of uniaxial compression and indirect tensile tests, and compared the estimated strength parameters with the measurement values. Here are our findings below. Rupture envelope of Kimachi sandstone agreed with Coulomb's failure criterion independent of water content and specimen temperature. Cooling barely changes the cohesion and angle of internal friction of the dry sandstone. On the other hand, the cohesion of saturated sandstone increases from room temperature down to － 170 ℃ broadly in a linear manner. The angle of internal friction shows interesting behavior of increasing after having decreased from room temperature to － 50 ℃ one time. The estimated strength parameters using general Mohr's failure criterion curves are not consistent with the shear test results. This means that it is difficult to estimate the strength parameters of the saturated sandstone by results of uniaxial compression and indirect tensile tests in an environment with low temperatures. However, we can almost estimate the strength parameters of the saturated sandstone in temperatures down to － 100 ℃ by using a compound envelope curve proposed in this paper.