钢-混凝土组合沉管结构抗剪机理

Shear Mechanism of Steel-concrete Composite Tunnel Structure

摘要:

以深圳至中山跨海通道沉管隧道设计方案为研究背景，建立沉管节段的精细化非线性有限元模型，进行四点反弯矩剪切试验仿真模拟.结果表明,在隧道横向，横隔钢板和混凝土分别承担斜向拉力和斜向压力，两者形成主要的受力体系；在隧道纵向，混凝土内未发现明显的横向应力分布变化；角钢连接件主要承担格室面板与混凝土间的剪力传递，拉拔作用不明显；在结构弹性状态下，各连接件抗剪刚度相近、剪力分布均匀；连接件附近混凝土开裂后逐步退出工作，但并不影响结构继续承载；剪切破坏过程表现为结构依次发生混凝土弯剪开裂、连接件处混凝土开裂、横隔钢板屈服，最终因混凝土剪切斜裂缝贯通达到结构极限承载力.

Abstract:

Based on the design of immersed tunnel of Shenzhen-Zhongshan Link, a refined nonlinear finite element model of immersed tunnel segment was built and a shear test was simulated. The results show that, in the transverse direction, the transverse steel diaphragm and the concrete bear the tension and compression, respectively, forming the main truss system. While in the longitudinal direction, no obvious lateral stress distribution is shown. The angle steel connectors mainly transfer the shear forces between steel and concrete, while the uplift forces are comparatively lower. At elastic stage, the shear stiffness of angle steel is close to each other and the shear force distributions are uniform. After the concrete near connectors cracking, the shear force undertaken by the structure is still increasing. In the whole shear process, the concrete cracks in bending area, the concrete cracks near the connectors, the yielding of transverse steel diaphragm, and the concrete diagonal cracks under shear occurred to the structure successively. The structure reaches the ultimate shear capacity with diagonal cracks, leading to the failure of the structure.