Deformation and Failure Mechanism of Surrounding Rock in Deep Soft Rock Tunnels Considering Rock Rheology and Different Strength Criteria

The long-term stability control of surrounding rock of deep high-stress soft rock tunnel has always been the research hotspot and difficulty of underground engineering. With the continuous increase of the number of ultra-kilometer mines, reasonable support design has an important impact on the efficient and safe production and sustainable development of deep coal resources. In view of the above problems, the formation mechanism of surrounding rock deformation zoning of deep high-stress soft rock tunnel considering rock rheology is analyzed, a three-stage strain-softening model considering rock rheology is established, and the concept of elastic-creep modulus is proposed based on this model. Combined with the rheological influence of rock and the test method of long-term strength of surrounding rock, the elastic–plastic solutions of surrounding rock of deep tunnel based on Mohr–Coulomb and Drucker–Prager strength criteria are derived, and the formulas for solving the radius of deformation zones of tunnel-surrounding rock are calculated. Meanwhile, combined with an engineering example, the radius of deformation zones of tunnel-surrounding rock based on different strength criteria and rock rheology is calculated and compared, and the correctness and superiority of this theory are verified by the field measured results. In addition, the influence of rock mechanical parameters on the range of deformation zones of tunnel-surrounding rock under different mechanical models is assessed. This work can provide guidance for long-term stability evaluation, support design, and disaster prevention of deep soft rock tunnels.