Abstract

Surrounding rock deterioration and large deformation have always been a significant difficulty in designing and constructing tunnels in soft rock. The key lies in real-time perception and quantitative assessment of the damaged area around the tunnel. An in-situ microseismic (MS) monitoring system is established in the plateau soft tock tunnel. In this paper, the probability density field of MS source based on probability mapping is proposed, which lays a foundation for accurately revealing the progressive damage characteristics of soft rock tunnel. The spatial distribution of MS dissipative energy is established. The morphological evolution of tunnel with multiple damage degrees in axial and radial direction is analyzed. The results show that the probability density field of MS source restructured by probability density at the located source position can more accurately delineate the damage distribution of tunnel alignment. Based on the basics MS energy parameter，a three-dimensional model was created to visualize the damage zone of the tunnel surrounding rock. The model depicted varying degrees of damage, and three high damage zones were identified. The rapid increase of the depth and extent of high damage area can be used as the criterion of dynamic warning of large deformation of surrounding rock of tunnel. This paper provides valuable insights for damage and dynamic warning of surrounding rock of high-stress soft rock tunnel.