| The uneven settlement of immersed tunnel and the improper disposal of the joint often lead to pipe cracking, leakage and other problems. Based on the immersed tunnel of Shenjiamen harbor in Zhoushan, Zhejiang, considering effects of temporary support cushion block to the internal force of immersed tunnel for the first time, mainly analyze deeply through experimental analysing, theoretical derivation and finite element simulation of pipe settlement and stress. In this paper, the main research results and innovations are as follows:(1) According to semi-rigid and semi-flexible connection mode, joints in immersed tunnel use the sliding bearing and shear spring form, so as to transfer moment and the contact force between the pipe sections. A theory calculation model on the internal force of an immersed tunnel is put forward, through considering the temporary support cushion block effect based on elastic foundation beam method.(2) On account of immersed tunnel of Shenjiamen harbor in Zhoushan City, conducting 1:10 reduced-scale model test indoor. In conditions of one end is fixed and the other end free, whether including back silting, different concentration of sand water ratio, analysing their influence to the value of base layer compression modulus. The results show that the influence of one end is fixed and the other end free to Es is the biggest, that of siltation condition is in the middle, and that of different concentration of sand water ratio is the smallest.(3) Internal force calculation results of immersed tunnel elements between no temporary support block condition and temporary support block condition are compared respectively. And the influence of different positions of temporary support block condition on internal force of immersed tunnel elements is studied. The result shows that bending moment of temporary support block condition mutates, the stress of pipe section changes and the pipe section cracks, the method of using the form of fixed support to imitate temporary support block is more reasonable, the most unfavorable position of temporary support block is near the pipe section 1/4 position, followed by 1/2,1/3,1/5 position.(4) With detailed calculating the internal forces in longitudinal section and cross section and the ground reaction force of shenjiamen port immersed tunnel element in Zhoushan, obtains the following conclusions. Under the temporary support block condition, it is recommended that pipe section design of supporting position should be calculated accorded to the bending moment value of block support position. The curves of ground reaction force with time changes a little, because the tube of immersed tunnel is long, the foundation returns to the original position after settlement for a period of time.(5) Using MIDAS/GTS software realistic simulate Zhoushan Shenjiamen Habor underwater immersed tunnel in three-dimensional, analysed the uneven settlement of each pipe section and found both ends of the differential settlement is about no temporary support cushion block of 1.6 times and temporary support cushion block of the immersed tunnel overall sedimentation is higher than that without the temporary support pad condition. |
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