Geomechanical Studies on Granite Intrusions in Alxa Area for High-Level Radioactive Waste Disposal

Geological storage is an important concept for high-level radioactive waste (HLW) disposal, and detailed studies are required to protect the environment from contamination by radionuclides. This paper presents a series of geomechanical studies on the site selection for HLW disposal in the Alxa area of China. Surface investigation in the field and RQD analyses on the drill cores are carried out to evaluate the rock mass quality. Laboratory uniaxial and triaxial compressive tests on the samples prepared from the drill cores are conducted to estimate the strength properties of the host rock. It is found that the NRG sub-area has massive granite intrusions, and NRG01 cored granite samples show the best rock quality and higher peak strength under various confinements (0–30 MPa). NRG01 granite samples are applied for more detailed laboratory studies considering the effects of strain rate and temperature. It is observed that the increasing strain rate from 1.0 × 10 −5 –0.6 × 10 −2 ·s −1 can lead to a limited increase on peak strength, but a much more violent failure under uniaxial compressive tests on the NRG01 granite samples, and the temperature increasing from 20 °C–200 °C may result in a slight increase of UCS, as well as more ductile post-peak behavior in the triaxial compressive tests.