In situ damage testing of rock mass in large underground cavern

To understand the spatial damage and deterioration mechanism of rock materials during excavation, an in situ test is carried out in an underground cavern 28·5 m in width, 21 m in height and 325 m in length. In this experimental cavern, the spatial distribution and intensity of rock damage are exposed by non‐destructive ultrasonic testing after excavation. The distribution function of spatial damage has been calculated based on the measured data. To protect wall rock, reparative measures of damaged rocks are discussed based on the measured results and the conception of damage reparation, which gives inspiration to the underground engineering design.