基于混凝土弹塑性损伤本构模型的盾构管片受力分析

在混凝土弹塑性损伤本构模型的基础上,考虑盾构管片拼装块与连接螺栓的非连续性和拼装块之间的接触关系,建立三维非连续接触计算模型。以苏州某地铁盾构隧道工程为例,对盾构管片的受力状况进行模拟计算,并与惯用法模型和修正惯用法模型的计算结果进行对比分析。结果表明:盾构管片内拱顶K拼装块部分区域的损伤因子超过了损伤临界值,这些部位将产生明显可见的裂缝;盾构管片拱顶与拱底内侧的受拉区域均产生了塑性变形,拱顶K拼装块的塑性区深度达到截面宽度的55%;盾构管片最大内力组合在两侧拱腰管片的接头处;三维非连续接触计算模型可以更好地反应管片接头对内力的影响和管片混凝土材料的受力及变形特性;模型中盾构管片接头处接触单元的设置消除了其他模型中接头刚度差异对计算结果的影响,对盾构管片抗压刚度及抗弯刚度均会产生影响。

Force Analysis of Segment for Shield Tunnel Based on Elastoplastic Damage Constitutive Model of Concrete

Based upon the elastoplastic damage constitutive model of concrete,considering the discontinuity between the assembly block of shield segment and connecting bolts as well as the contact relationship between each assemble block,a 3D discontinuous contact computational model was built.Taking the shield tunnel project of certain metro in Suzhou for example,3D discontinuous contact computational model was used to simulate the force condition of shield segment.Comparative analysis was conducted between the simulated results and those obtained by routine method model and modified routine method model respectively.Results show that the damage factor of some zones on the K assembly block at the vault in shield segment has exceeded the damage threshold value,and visible cracks thus appear on these zones.Plastic deformation appears on the inner side of shield segment top and bottom subjected to tension.The plastic zone depth of the K assembly block at shield segment top has reached 55% of the section width.The maximum internal force combination of shield segment locates at the joint of the haunch segment on both sides.3D discontinuous contact computational model can better reflect the influence of segment joint on the internal force as well as the stress and deformation characteristics of concrete material for segment.The setup of the contact element at the joint of shield segment in the model has eliminated the influence on the calculation results by the diversity of the joint stiffness in other model.Both the compressive stiffness and the bending stiffness of shield segment will be affected.