Reliability Analysis of Circular Tunnel Face Stability Obeying Hoek-Brown Failure Criterion

摘要

The first order reliability method (FORM) is applied to analyse the face stability of a circular tunnel driven by a pressurized shield, in a highly fractured rock mass characterized by the Hoek-Brown non-linear failure criterion. The collapse failure mode is studied in this paper. We employ a limit analysis approach with an advanced rotational failure mechanism. Rock mass parameters σ_(ci), GSI and m_i, are regarded as independent random variables with normal distributions. The reliability problem is solved numerically using FORM with an implicit limit-state function (LSF). A sensitivity analysis is conduct as well. The results show that: 1) The reliability index increases with an increasing support pressure; 2) all three random variables considered are resistance variables; 3) σ_(ci) is found to be the most important variable with higher support pressures, whereas, GSI becomes the most influential variable with lower support pressures.