Development and applicability verification of laboratory cyclic box shear test method using large rock blocks

In-situ rock shear tests using large rock blocks are commonly used to investigate the strength characteristics of rock mass. However, the initial stress and boundary conditions are unknown; therefore, several difficulties in the interpretation of test results are encountered, among other problems. In recent years, with the advancements in aseismic design in the evaluation of the foundation rocks and surrounding slopes of nuclear power plants, dynamic nonlinear analysis methods that account for the destruction of rocks are being developed. However, there are few achievements for the natural rock mass, and there is a lack of data for verification. Therefore, in this study, we developed a laboratory cyclic box shear test method using large rock blocks. This method can be utilized to acquire verification data for dynamic nonlinear analysis and resolve the problems with the in-situ rock shear test. In addition, the applicability of the test method developed herein was verified by comparing the results obtained through the method with the results of laboratory element tests using the same rock blocks.