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从风险水平的角度初步量化分级安全储备,提出在给定可靠性水平下直接计算隧道支护抗力的方法。该方法首先基于室内和现场试验的数据,利用广义3倍标准差准则得到参数的统计特征;遵循利用围岩应变值作为隧道支护设计基础的理论,采用极限状态函数建立功能函数方程;然后基于一次逆可靠度算法,结合Nataf变换和Cholesky分解构建详细计算程序;最后计算局部安全系数。以经典软岩参数为例,通过一次二阶矩法(FORM)验证该方法精度;分析相关性和初始应力场对隧道支护抗力的影响。最后计算确定在可接受风险水平下的隧道支护抗力及相应局部安全系数。
From the perspective of risk level, we initially quantify the classified safety reserve and propose a method to directly calculate the tunnel support resistance under a given level of reliability. Firstly, based on the data of indoor and field tests, the statistical characteristics of the parameters are obtained by using the generalized 3-fold standard deviation criterion. Following the theory of using the surrounding rock strain value as the foundation of tunnel support design, the functional state equation is established by using the limit state function. An inverse reliability algorithm, combined with Nataf transform and Cholesky decomposition to build a detailed calculation program; Finally, the calculation of local safety factor. Taking the classical soft rock parameters as an example, the accuracy of this method is verified by a second-order moment method (FORM). The influence of the correlation and the initial stress field on the tunnel support resistance is analyzed. The final calculation determines the tunnel support resistance and the corresponding local safety factor at an acceptable level of risk.