BASIC PHYSICO-MECHANICAL PROPERTIES AND TIME-TEMPERATURE EFFECT OF DEEP INTACT ROCK FROM BEISHAN PRESELECTED AREA FOR HIGH-LEVEL RADIOACTIVE WASTE DISPOSAL
Abstract：Physico-mechanical property is one of the important aspects for site selection，design，construction and performance assessment of high-level radioactive waste(HLW) disposal. Through a nationwide screening and comparison，Beishan area，a Gobi desert in Gansu Province，is considered as a suitable candidate for HLW geological repository in China. The dominant lithology in Beishan area is porphyritic monzonitic granite and tonalite，with high homogeneity. The deep intact rock of Beishan area has the properties of high density，low porosity，high mechanical strength，low strain and high brittleness. The strain and acoustic emission behavior of granite under constant loading with different temperatures(room temperature，50 ℃，90 ℃) and confining pressures (0，10 and 30 MPa) are studied through creep test. The results indicate that the effect of temperatures and confining pressure on the mechanical property is significant. When the confining pressure is 10 and 30 MPa respectively，the elastic modulus increases with temperature increasing to about 70 ℃，and then decreases a little with the temperature increasing higher；the crack damage stress linearly decreases and Poisson¢s ratio linearly increases separately with the temperature increases. The steady state creep strain rate increases and the time to failure response at the same stress ratio reduces with the temperature increasing. The time to failure increases rapidly as the constant load decreases. The axial creep strain increases and time to failure of granite at the same stress ratio increases rapidly when confining pressure increases.
