车辆荷载下沉管隧道动力响应有限元分析

依托宁波甬江沉管隧道工程,利用MIDASGTSNX软件建立沉管隧道三维有限元模型。采用非线性弹簧模拟接头,选取影响接头刚度的主要部件,依据各部件材料特性对接头各向刚度进行取值。通过对路床网格节点添加线性变化的荷载来模拟车辆行驶,对管节及接头产生的动力响应进行分析。结果表明,有限元计算结果与理论计算结果得到的管节中点竖向位移幅值接近,说明有限元模型的可靠性;江中段管节中点竖向位移较岸边段大,靠近岸边的接头两端竖向位移差较中间接头大;车辆荷载下沉管段最大主应力的最大值出现在沉管段北端的顶板处,且靠近岸边的接头剪力和弯矩大于中间接头,需要重点监测。

FINITE ELEMENT ANALYSIS FOR DYNAMIC RESPONSE OF IMMERSED TUNNEL UNDER VEHICLE LOAD

Based on Ningbo Yongjiang immersed tunnel project, with the help of MIDAS GTS NX, a three-dimensional finite element model of the immersedtunnel is built, and nonlinear spring model is used to simulate the joint. Considering the mainly parts of joint and relying on their material characteristic, isotropic stiffness of the joint can be determined. The linear change load is added to the road bed grid node to simulate the vehicle driving, and the dynamic response of elements and joints is analysed. The results show that thevertical displacement amplitude of element midpoint, which given through finite element calculation, is closed to that given through theoretical calculation, so this finite element model is reliable. The vertical displacement of element that near to the middle of the river is larger than that near to the bank side, and the vertical displacement difference of side joint is larger than that of middle joint. The maximum value of the maximum principal stress of elementsof the vehicle load appears at the north end of tunnel roof, and the shear and bending momentnear side joint is larger than that of middle joint, so these positions are needed to be mainly monitored.