In order to investigate the mechanism on zonal disintegration within rockmass around deep tunnel under static-dynamic coupling loading

by using the Instron electro-hydraulic and servo-controlled material testing machine

the test of deep tunnel on plaster model subjected to static-dynamic coupling loading is carried out. In order to further analyze the mechanical nature of layered fracture of surrounding rock around deep tunnel under static-dynamic coupling loading

surrounding rock around deep tunnel is regarded approximately as a combination of samples subjected to biaxial static-dynamic coupling loading; and the biaxial test of red sandstone subjected to static-dynamic coupling loading is performed. Experiments indicate that layered fracture of surrounding rock around deep tunnel may occur when the axial stress of tunnel is the maximum principal stress and more than a certain value. Layered fracture of surrounding rock around deep tunnel may also occur when the axial stress of tunnel is the maximum principal stress and the superposition value of axial stress and external disturbance stress is more than a certain value. Larger tunnel diameter may make layered fracture of surrounding rock around deep tunnel occur more easily under the same static-dynamic coupling loading. The larger superposition value of axial stress and external disturbance stress may make more layered fracture of surrounding rock around deep tunnel occur under the same tunnel diameter. The failure mode of statically loaded sample under periodic dynamic load changes according to different static stress states; and fracture surface of sample is generally perpendicular to the minor principal stress direction (in plane of minor principal stress) and tends to agree with the maximum principal stress direction. There is the foregoing stress state in surrounding rock around deep tunnel triggering layered fracture

and then leading to zonal disintegration within rockmass around deep tunnel under static-dynamic coupling loading.