为了控制地层裂缝的产生和贯穿从而防止突涌水事故的发生,把拱顶沉降作为优化设计中的控制指标,通过控制拱顶沉降来达到控制拱顶地层裂缝产生和贯穿的目的.针对全封堵的防排水形式和有限元软件特点提出了通过等效泊松比的方法来施加围岩荷载和水荷载的思路;提出了包括最优化参数获取,设计变量敏感性分析和优化设计效果评价在内的完整的优化设计分析过程;针对青岛胶州湾海底隧道的具体断面形式进行优化分析:优化后拱顶沉降值减小为原设计的44%;以获得的最优设计为参考点,分析了设计变量的改变对拱顶沉降的影响,分析得出的规律性认识可以更好地指导设计;通过比较优化前后衬砌结构受力,可知优化后的衬砌结构在受力方面也得到了改善.
Crown settlement is set to be the objective Tunnel function and efforts are put on searching tunnel shape which causes the least crown settlement. In this way, the safety of subsea tunnel can be guaranteed by controlling the formation and development of the cracks. According to the total-closure waterproof feature equivalent poisson ratio is adopted to apply ground pressure as well as water pressure which is a reasonable ways to simulate use FEM. Whole process optimization is put forward which contains optimization parameters acquisition, design variable sensitivity analysis and evaluation of the optimal design. According to the characteristics of subsea tunnel in Kiaochow Bay, optimization method mentioned above is used to make optimization analysis: crown settlement is reduced significantly after optimization; the optimum design set is made for the reference point to study the relation between crown settlement and design variables which can offer guidance for design; the stress state is also proved improved after optimization.