隧道可靠度BFOA逆向寻优方法及其工程应用

Inverse reliability calculation method of tunnel reliability based on BFOA optimization and its engineering application

为了能够根据预期可靠度要求进行隧道支护参数逆向求解设计,基于软弱围岩失稳变形的极限状态方程与细菌觅食优化算法(BFOA)建立一种隧道可靠度逆向求解方法。实际应用过程中,首先采用概率图法验证围岩基本力学参数的分布特征;然后通过Monte Carlo抽样的方式,根据围岩变形极限状态方程建立隧道可靠度求解模型并以此作为优化算法的响应面函数;采用BFOA算法进行待求工程参数的寻优计算,实现能够满足预期结构可靠度的隧道支护阻力逆向求解。讨论所述方法搜索区间开度与迭代次数对计算精度与效率的影响,确定合理的寻优、抽样迭代次数阈值分别为1600、1×10^(5)次,并对围岩各物理参数的敏感性进行分析。结果表明,所述方法能够有效实现对隧道支护阻力的逆向求解,获得所需的工程设计指标。

To carry out the inverse solution design of the tunnel support parameters according to the expected reliability requirements,a method for the inverse solution of tunnel reliability is established based on the limit state equation of the instability deformation of the weak surrounding rock and the bacterial foraging optimization algorithm(BFOA).In the actual application process,this paper firstly verifies the distribution characteristics of the basic mechanical parameters of the surrounding rock through the probability graph method.Then the Monte Carlo sampling method is used to establish the tunnel reliability solution model according to the surrounding rock deformation limit state equation,which is taken as the response surface function of the optimization algorithm.BFOA performs optimal calculation of the engineering parameters,and realizes the reverse solution of tunnel support resistance that meets the expected structural reliability.On this basis,the influence of factors such as the opening of the search interval and the number of iterations of the method on the calculation accuracy and efficiency is discussed,and the reasonable thresholds for the number of optimization and sampling iterations are determined to be 1600 and 10^(5) times respectively.At the same time,the sensitivity of each physical parameter of the surrounding rock is analyzed.The application results show that the method can effectively realize the reverse solution of the tunnel support resistance,obtain the required engineering design indicators.