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Study on the Mechanisms of the Influence of Rock Mass with Previous Highstress Damage on Surrounding Rock Supports
(1. NHRI Materials & Structural Engineering Department, Nanjing 210029; 2. Department of Civil and Airport Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211106; 3. School of Water Resources and Hydropower Engineering,Wuhan University, Wuhan 430072)
Abstract The rock mass in the fault zone is characterized by fissures and previous high-stress damage. To explore the mechanical property of rock mass with high-stress previous damage after excavation when a tunnel passes through a fault zone and its impact on supports, different discrete element numerical models of two unloading paths are designed: pre-peak unloading, reflecting the excavation of ordinary tunnels; post-peak unloading, reflecting the excavation of tunnels in the rock mass with high-stress previous damage in a fault zone. The calculation parameters of discrete element models are calibrated through the triaxial compression test of white sandstone samples, and then numerical calculations are conducted to compare and study the mechanical behaviors of surrounding rocks in these two unloading paths. The results show that the self-bearing capacity of the surrounding rock with high-stress previous damage collapses at a faster speed after excavation-induced unloading, so supports shall be provided more timely; the support strength required is significantly increased to achieve the identical amount of deformation of surrounding rock; and it is more difficult to support the micromechanism for the significant development of tensile microcracks.
Abstract：
The rock mass in the fault zone is characterized by fissures and previous high-stress damage. To explore the mechanical property of rock mass with high-stress previous damage after excavation when a tunnel passes through a fault zone and its impact on supports, different discrete element numerical models of two unloading paths are designed: pre-peak unloading, reflecting the excavation of ordinary tunnels; post-peak unloading, reflecting the excavation of tunnels in the rock mass with high-stress previous damage in a fault zone. The calculation parameters of discrete element models are calibrated through the triaxial compression test of white sandstone samples, and then numerical calculations are conducted to compare and study the mechanical behaviors of surrounding rocks in these two unloading paths. The results show that the self-bearing capacity of the surrounding rock with high-stress previous damage collapses at a faster speed after excavation-induced unloading, so supports shall be provided more timely; the support strength required is significantly increased to achieve the identical amount of deformation of surrounding rock; and it is more difficult to support the micromechanism for the significant development of tensile microcracks.
TANG Lei1 WEN Jiaqi1 ZHAO Xinming2 JIANG Bo2 ZHAN Qibing1,
3
.Study on the Mechanisms of the Influence of Rock Mass with Previous Highstress Damage on Surrounding Rock Supports[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(4): 50-57
2022, Vol. 59 