地面堆载作用下盾构隧道管片开裂行为分析

针对盾构隧道管片的非线性响应提出一种基于地层结构法的数值模拟手段,考虑土体、混凝土、钢筋和接触的非线性力学行为,将能够准确描述混凝土受拉压与剪切行为的总应变开裂模型赋予衬砌管片。针对实际工程的数值计算结果能够与隧道沉降及实际裂纹开展特征吻合,验证了该数值分析模型的有效性。引入最大裂缝宽度、开裂因子和开裂率等指标评价及预测衬砌开裂行为。研究结果表明:堆载作用下管环的主要损伤区扩展,深度增加,并萌生出宏观裂纹。基于对上、下行线开裂行为的对比分析可知堆载高度和堆载偏移距离对管片开裂行为有重要影响。

Nonlinear structural analysis on cracking behavior of shield tunnel segment under surface loading

An FEM method based on layer structure method was put forward, which focused on the nonlinear response of TBM tunnel lining. Nonlinear mechanical behaviors of soil, concrete, reinforcement and contacts were considered in this model. Total strain based crack model which describes the tensile, compression and shear behaviors was adopted upon the tunnel lining. The numerical results match well with the tunnel monitoring settlement and crack distribution, which verifies the effectiveness of the FEM model. Several indexes including maximum crack width, crack index and crack ratio were introduced to evaluate and forecast the crack behavior. The result shows that both the area and depth extend in main damage zones under surface loading, when the macro cracks appear. Based on the contrastive analysis between the upline and the downline, height and offset of the loading turn to be important parameters for the nonlinear crack response of the lining.