不均匀土体位移引起地下管线弯曲变形研究

Investigation of bending deformation of underground pipelines induced by differential ground movements

隧道开挖和管线置换引起的应力变化将不可避免地导致土体位移,进而对上覆既有管线产生诸多的不利影响。国内外学者对管-土相互作用开展了大量的研究,但用于预估隧道开挖和管线置换引起既有管线弯曲变形的简单并且有效的设计图表尚未提出。采用ABAQUS商业软件,对隧道-土-管线、管线置换-土-管线间的相互作用开展系统的有限元仿真模拟。通过采用管线不同运动方向下的等效管-土相对刚度,提出了隧道开挖和管线置换引起的管线弯曲变形的设计图表,并采用现场实测数据和离心模型试验结果验证此设计图表的合理性。设计图表中的管线最大弯曲曲率与土体最大曲率的比值和管-土相对刚度具有非常好的相关性。工程师一旦得到隧道开挖或管线置换引起的土体位移、管线尺寸、管线参数和土体参数,此设计图表可用来预测隧道开挖或管线置换引起既有管线的最大弯曲曲率。

Stress changes induced by tunnel excavation and static pipe bursting inevitably lead to soil movements, and cause adverse effects on existing pipelines. Although the pipe-soil interaction has attracted increasing research attention worldwide, a simplified design code has not been developed to directly estimate bending strains of existing pipelines due to tunnel excavation and static pipe bursting. In this study, we use the commercial software of ABAQUS to systemically simulate the tunnel-soil-pipeline and pipe bursting-soil-pipeline interactions, and develop a single dimensionless plot for calculating bending strains of existing pipelines due to static pipe bursting and tunneling by using equivalent soil-pipe stiffness. Results of field monitoring and centrifuge tests are adopted to verify the proposed dimensionless plot. The ratio of the maximum pipeline curvature to the maximum ground curvature correlates well with the proposed equivalent subgrade soil stiffness. By given the ground displacement profile, pipe dimension, pipe material properties, and soil properties, engineers can apply the proposed dimensionless plot to directly estimate maximum pipeline curvature and/or strains due to tunneling and pipe bursting.