基于响应面和重要抽样法的隧道衬砌结构时变可靠度

由于隧道衬砌结构极限状态方程高度非线性,直接采用一般的可靠度计算方法得到的是几何可靠度,存在较大误差,需进行改进.结合响应面法和重要抽样两种方法,利用响应面法得到的验算点作为重要抽样法的抽样中心,进而求解结构的可靠度指标.在该理论的基础上,考虑结构抗力随时间衰减的因素,利用Matlab软件编制了隧道在服务寿命期限内的时变可靠度指标的计算程序,并通过回归分析,得到了时变可靠度指标随着时间呈指数递减的规律.通过耐久性系数与时变可靠度指标的对应关系,可得到衬砌结构任意时刻的耐久性系数,该系数则是衬砌结构耐久性设计的关键.该方法对功能函数高度非线性的工程较适用,并且为结构耐久性设计提供了基础.

Response Surface and Importance Sampling Method based Tunnel Lining Structure Time dependent Reliability Research

Because tunnel lining structure limit state function are highly nonlinear, the geometric reliability obtained by a direct adoption of the general method is of a considerable error and an improvement is in need. By combining the response surface method and important sampling methods, the checking point sampling was obtained as an important center of the sample. Then the structure of the reliability indexes were solved. Based on a consideration of the factors of the resistance to decay with time, the Matlab software was resorted to drawing up the time dependent reliability index calculation program of tunnels in the service life period,and a regression analysis showed that the time dependent reliability indexes decreased exponentially with time. By the correlation of durability coefficient and time dependent reliability indexes, the durability coefficient at any time was available, which was key to the durability design of lining structure. The proposed method is suitable for highly nonlinear performance function engineering and it lays a good foundation for structural durability design.