隧道下穿时地表房屋变形开裂的定量评估

QUANTITATIVE EVALUATION OF HOUSE DEFORMATION AND CRACKS CAUSED BY TUNNEL-CROSSING

城市隧道下穿时,普遍存在着地表房屋变形超限、倾斜开裂等风险控制难题,结合厦门机场路隧道下穿建筑群的工程实践,分别采用W-W破坏准则、屈服接近度模型和Mazars损伤模型,对地表房屋变形开裂进行定量的计算与评估。计算结果表明:屈服接近度模型实质为广义的塑性区,其结果为定量的房屋开裂安全度分布;Mazars损伤模型为典型的拉损伤模型,根据其损伤变量的大小,可以对应地评估房屋开裂程度。同时,分别基于屈服接近度模型和Mazars损伤模型,对隧道下穿过程进行数值模拟,二者结果均较好地反映了房屋变形开裂过程与施工过程的非线性相关性,由此实现了对房屋变形开裂全过程的量化评估与控制。研究结果显示,开裂过程的计算评估结果与现场房屋裂缝、变形实测结果一致性良好。

House cracks and over-deformation are hot issues in tunnel-crossing urban territory, and related studies of calculation of house cracks and its risk evaluation lag far behind the needs of engineering. Based on practice of Xiamen Airport Road Tunnel-crossing building blocks, house deformation and cracks can be quantitatively calculated and explained with W-W failure criterion, Mazars damage model, and yield approach index（YAI） model. By comparison, results show that YAI model is essentially one kind of generalized plastic zone; and its result is distribution of safety degree of house cracks. And Mazars damage model is typical tensile damage model, thereby house cracks can be evaluated by the damage factor. Meanwhile, with YAI or Mazars damage model for numerical simulation of tunnel-crossing process, nonlinear relationships between house cracks and tunnel construction process will be nicely established; thus house cracks can be quantitatively evaluated and pre-controlled. As a whole, simulation results of deforming and cracking process have good coincidence with in-situ measured house fractures and deformation.