乌鞘岭公路隧道破碎岩体段结构可靠性评价

Evaluation of Structural Reliability of Broken Rock Mass Section of Wushaoling Highway Tunnel

以乌鞘岭公路隧道破碎岩体段为研究对象,基于随机有限元的结构可靠性理论,统计计算试验所得各个随机变量的数字特征及分布类型;建立极限状态方程后,对乌鞘岭隧道破碎岩体段建立随机有限元模型进行结构可靠性计算。结果表明:随机变量直方图拟合曲线均比较光滑,而且抽样数据各个子序列均有数据且无间隙,表明所进行的随机抽样样本量充分;在此基础上,计算此段隧道的初期支护和二次衬砌各个最大应力及锚杆最大轴力的直方图和概率分布曲线,得到的可靠度及失效概率结果说明初期支护和锚杆最大轴力可靠性偏小,而二次衬砌的可靠性较大,本段隧道整体处于安全状态;隧道结构可靠性灵敏度分析得到:不同随机变量对隧道结构不同应力有着不同影响程度,且喷射混凝土厚度对隧道结构内力影响最为显著。

Taking broken rock mass section of Wushaoling highway tunnel as the research object, based on the structural reliability theory of stochastic finite element, we performed statistical analysis of the digital features and distribution type of random variables acquired from experiment. After establishing the limit state equation, we established the random finite element model of the broken rock mass section of Wushaoling highway tunnel and calculated the structural reliability. The result shows that the fitting curve of random variable histogram is smooth, and each subsequence of the sampling data are filled and no clearance, which indicates that the sample size of the random sampling is sufficient. On this basis, we calculated the histograms and probability distribution curves of the maximum stresses of primary support and secondary lining and the maximum axial force of anchor of the tunnel section. The results of reliability and failure probability show that the reliability of primary support and axial force of anchor are small, while the reliability of secondary lining is larger, the whole tunnel section is safe. The sensitivity analysis of tunnel structure reliability shows that different random variables have different influence degree on different stresses of tunnel structure, and the influence of thickness of sprayed concrete on tunnel structure internal force is most significant.