In-situ test method for surrounding rock relaxation depth in columnar jointing rock mass cavity project

The invention relates to an in-situ test method for the surrounding rock relaxation depth in a columnar jointing rock mass cavity project. The in-situ test method includes the steps of designing and arranging test drilling holes which are formed in the periphery of a cavity excavated in a columnar jointing rock mass and parallel or perpendicular to the axis of a column body of the columnar jointing rock mass, selecting test projects, determining the relaxation depth, and comprehensively conducting the test. The test drilling holes are distributed in key portions of a monitored fracture surface after the cavity is excavated, surrounding rock elastic waves and jointing fissure characteristics of the monitored fracture surface of the excavated cavity are obtained through an in-situ test means which integrates digital drilling with camera shooting and integrates single hole sound waves with across hole sound waves, and the surrounding rock relaxation depth is comprehensively judged according to reduction of the wave velocity of the sound waves in an unloading relaxation area and the corresponding rock mass fracture condition. The technical scheme is simple, the test means is reliable, comprehensive collection and comparison analysis of columnar jointing rock mass unloading relaxation information are ensured, the surrounding rock relaxation depth is accurately confirmed, the in-situ test method can be widely applied to columnar jointing rock mass excavation and supporting projects such as water conservancy and hydropower projects, traffic projects and underground test site projects.