航道疏浚对海底盾构隧道纵向稳定性的影响研究

对海底长距离、高水压、大直径盾构隧道纵向稳定性的特点和影响因素进行了分析,并通过工程实体对航道疏浚这一影响因子进行研究。结合航道疏浚的特点、工艺和工序,选取纵向长2.4km的大型模型,采用数值模拟方法分别研究了航道疏浚深度、疏浚工序及回淤厚度等因素对结构纵向变形、受力的影响程度,初步得到了航道疏浚深度对隧道结构稳定性的控制作用。同时,给出了疏浚深度与结构变形、受力的非线性关系,即航道疏浚深度超过7m后隧道纵向变形趋势明显;提出了疏浚控制深度的指标,疏浚规划方案宜进行优化。最后,探讨了盾构隧道结构和周边地层的加固方案,以保证结构稳定性。初步研究结果对于海底盾构隧道前期规划、设计有一定的参考价值,相关研究还需要进一步深化。

STUDY ON INFLUENCES OF CHANNEL DREDGING ON LONGITUDINAL STABILITY OF SUBSEA SHIELD TUNNEL

The characteristics and influence factors of the longitudinal stability of subsea tunnel with long-distance,high water pressure and large diameter are analyzed;and taking a certain project for example,a study on channel dredging as a new and important influence factor is carried out. Combined with the characteristics,techniques and working procedure of channel dredging,numerical simulation method with a large-scale model with 2.4 km long tunnel structure and seabed stratum is performed. The relations and influences of the channel dredging depth,the dredging working procedure,the alluvium thickness,etc. are presented on structure longitudinal stability,such as deformation and stress. Then,some conclusions of the control function from channel dredging depth to tunnel structure stability are drawn;and a nonlinear relation between dredging depth and structure transmutation and stress is achieved. It can be seen that tunnel longitudinal transmutation is obvious when channel-dredging depth is larger than 7 m. Also,it is pointed out that the control index of channel dredging depth and the layout project of channel dredging should be optimized. Finally,the reinforcing method of the shield tunnel structure and the surrounding stratum is given to guarantee the structure stability. The primary research results have some references to the proper layout and design of the subsea tunnel;meanwhile,more detailed research is also needed in the future.