基于均匀设计-响应面-有限元法的软岩隧洞围岩与衬砌结构协同承载可靠性分析

软岩隧洞围岩力学特性和衬砌结构受力皆具有显著的随机性、未确知性等不确定性,基于确定性分析的结构安全设计方法往往难以全面合理地反映软岩隧洞工程的复杂性;传统的可靠度计算理论则对于由围岩和支护系统构成的地下结构真实的功能函数无法从理论上给出显式表达,从而制约了可靠度计算理论在隧洞工程中的应用。在以数理统计方法为核心的可靠度计算理论基础上,结合均匀设计方法、响应面法和有限元数值模拟方法,借助于《水工隧洞设计规范》(SL 279—2016)中衬砌结构的承载力极限状态函数,构建了围岩和衬砌结构协同承载的荷载效应响应面显式表达式,由此提出了一种软岩隧洞围岩和衬砌结构协同承载的可靠性评价方法。采用该方法分析了影响联合承载特性的单因素随机变量,辨识了影响围岩和衬砌结构协同承载可靠性的主要因素,最后将该方法应用到具体工程中进行检验。通过与传统可靠度计算方法进行对比可知,该方法满足了精度,简化了流程,提高了效率,表明其具有很好的适应性和可行性。

Reliability Analysis of Collaborative Bearing Capacity of Surrounding Rock and Lining Structure in Soft Rock Tunnel Based on Uniform Design,Response Surface,and Finite Element Method

The mechanical properties of the surrounding rock of soft rock tunnel and the stress of the lining structure are highly random and uncertain. The structural safety design method based on deterministic analysis could hardly reflect the complexity of soft rock tunnel engineering, while traditional reliability calculation theory does not give an explicit expression to the real function of underground structure composing the surrounding rock and support system, hence hindering the application of reliability calculation theory in tunnel engineering. In view of this, we present a reliability evaluation method for the collaborative bearing capacity of surrounding rock and lining structure by constructing an explicit expression of response surface according to the limit state function of bearing capacity in SL 279—2016 (Code for design of hydraulic tunnels) in the light of uniform design and reliability theory. The single factor random variables that affect the collaborative bearing characteristics are analyzed, and the major factors of reliability are identified. The present method is applied to a specific project and compared with the traditional reliability calculation method. Results manifest that the present method simplifies the calculation, boosts accuracy and efficiency, and is well adaptive and feasible.