放坡疏浚对海陆交接段隧道稳定性的影响研究

摘要

For studying the influence of channel dredging on underwater tunnel structure,taking subsea tunnel in the land-sea connecting area for example,the surrounding rock is modeled as continuous media based on Drucker-Prager yield criterion.The influencing degrees of the channel dredging,including the channel dredging gradient,the alluvium thickness and the dredging working procedure,etc,on tunnel structure deformation and stress are studied by means of finite element software ANSYS.The numerical calculation results show that:1 )The differential deformations along the longitudinal direction of tunnel is increased by channel dredging;the vertical displacement of tunnel roof at underwater section is the largest;and the equivalent stresses of the both sides of tunnel are the largest.2)The grading gradient is related to slope;the change of gradient affects structure in land and water a little,and mainly affects the deformation and stress of structure in grading section.3)The influence of back-silting and desilting thickness on structural deformation and internal force should also be considered in the channel planning and design phases.%为了研究航道疏浚对水下隧道结构的影响，选取海陆交接处的隧道段作为分析对象，考虑隧道围岩为基于Drucker－Prager屈服准则的连续介质，利用ANSYS有限元软件分析了航道疏浚对结构变形、受力的影响，重点对航道放坡疏浚条件下放坡坡度、回淤厚度及疏浚工序等因素的影响程度进行了研究。数值计算结果表明：航道疏浚清淤增加了沿隧道纵向的差异变形，且影响较大的水域段最大竖向位移发生在隧道顶部，而最大等效应力则出现在隧道两侧；航道疏浚放坡坡度大小除了与坡体本身的稳定性相关外，在水深一定条件下，坡度的改变对结构水域段和陆域段的影响甚微，主要影响到放坡段的结构变形和内力变化速率，实际工程中应综合经济性评价与效果分析确定疏浚坡度的取值；此外，回淤、再清淤厚度对结构变形和内力的影响也是航道规划、设计中需要考虑的主要问题。