多批次预制的内河沉管隧道干坞坞口封闭方案研究

Study on Dry Dock Gate Closure Scheme for Multi-batch Prefabricated Inland River Immersed Tunnel

为优化多批次预制的内河沉管隧道干坞坞口封闭方案,以广州某典型软土地基中的沉管隧道干坞工程为背景,提出一种半重力式坞门墩+钢坞门的坞口封闭方案,并将其与围堰方案进行了经济合理性比较。通过建立三维有限元模型,分析地连墙接头类型、墙体厚度、坞门墩平面长度等敏感性因素,揭示了格构式地连墙坞门墩的受力机制。研究结果表明:对于多批次预制的内河沉管隧道,半重力式坞门墩+钢坞门坞口封闭方案的造价比围堰方案降低20%以上,且缩短了半年以上的工期;坞门墩格构式地连墙呈现以水平向受力为主的双向板受力特征;刚性接头坞门墩整体性好,柔性接头坞门墩在墙顶盖板的约束下也具有较好的整体性,但二者的位移、弯矩大小和形状均存在差异;随着墙体厚度的增加,墙体的位移减小,弯矩增大;随着坞门墩平面长度的增加,墙体的位移减小,弯矩减小。

To optimize the multi-batch prefabricated dry dock closure scheme of inland river immersed tunnel,a semi-gravity dock gate block&steel dock gate closure system was proposed based on a typical immersed tube tunnel dry dock on soft soil foundation in Guangzhou,and the economic and rational comparison was made with the dock gate cofferdam closure scheme.A 3D model was established based on numerical software to reveal the mechanical mechanism of lattice dock gate block,and the sensitive factors such as joint type,wall thickness and dock gate block length were discussed.The results show that the cost of the semi-gravity dock gate block&steel dock gate closure scheme is 20%lower than that of the multi-batch prefabricated inland river immersed tunnel,and the construction period is also reduced by half a year.The lattice dock gate block shows the similar characteristics as bidirectional plate,in which the bearing force is mainly in horizontal direction.The rigid joint dock gate block has strong overall cooperative force capacity and the flexible joint dock gate block also has good overall cooperative force capacity under the constraint of the top cover of the wall,but the amplitude and shape of their displacement and bending moment are different.With the wall thickness increases,the wall bending moment increases but the wall displacement decreases.With the length of dock gate block increase,both the wall bending moment and displacement decrease.