海底隧道衬砌结构设计

 海底隧道围岩水通常具有稳定水位和充足补给，隧道结构受长期的水压力作用，衬砌计算中应首先确定水压力荷载大小，并综合考虑隧道涌水量的大小，由此对衬砌断面的拟定、衬砌类型的选择、衬砌结构安全性进行评价计算。正在建设的厦门翔安海底隧道衬砌结构设计时，通过不同防排水方式下衬砌背后水压力特征的模型试验表明，作用于全封闭衬砌上的水压力是不能折减的；根据陆域和海域不同地段预测全隧道涌水量，由于无法满足运营期间的排水，衬砌结构必须采用全封闭形式或限制排放形式；利用ANSYS有限元软件，根据外水压力大小与围岩压力组合下对不同的隧道衬砌断面进行对比分析计算，以得出结构受力最为经济合理的断面形式；并以此断面按荷载结构模式法进行全封闭衬砌结构计算。计算结果及建设的实际情况表明衬砌受力合理。

LINING STRUCTURE DESIGN OF SUBSEA TUNNEL

The water above surrounding rock of subsea tunnel is of a stable water level with plentiful supply. The tunnel lining structure bears water pressure for long time. In design of lining structure，the water pressure should be identified firstly. The evaluation and calculation of tunnel cross-section layout，lining type and structure safety are carried out based on water pressure and water inflow. For Xiamen Xiang¢an subsea tunnel under construction，model test of the external water pressure feature under different drainage modes indicates that the water pressure on fully-enclosed lining should be not discounted. The water inflow in the tunnel is forecasted；and the lining is designed in fully-enclosed or limited drainage type since the drainage in operation stage can not be satisfied. The most economic and reasonable lining cross-section is obtained based on structure analysis and comparison under different lining sections with combination of water pressure and surrounding rock pressure by means of finite element software ANSYS. The recommended lining section is proven to be reasonable by both computing results and construction practice.