供水管道45°斜穿地裂缝足尺模型试验研究

Full-scale model test on feed pipeline crossing earth fissure with an angle of 45°

西安地裂缝是一种典型的城市地质灾害,对供水管道造成严重危害。以西安市球墨铸铁供水管道穿越地裂缝为工程背景,通过供水管道45°斜穿地裂缝足尺模型试验,研究地裂缝作用下供水管道的变性特征、结构应力与土压力变化规律。试验结果表明,在地裂缝作用下,上盘管道产生差异沉降,远离地裂缝管道末端沉降量最大,上盘管道顶部和底部部分区域形成脱离区或脱空区。管道表现出复杂的伸臂梁受力模式,竖向上上盘管道产生“上凸下凹”的弯曲变形,顶部形成受拉区,底部形成受压区;下盘管道产生“上凹下凸”的弯曲变形,导致其顶部形成受压区,底部形成受拉区;水平方向上,地裂缝与管道锐角侧形成受拉区,钝角侧形成受压区。管道柔性T型接口可一定程度调节管道两侧差异沉降,且在管道接口处轴向应力最大。基于模型试验结果,提出地裂缝发育区管道建设应合理规划线路、浅埋或架空布设、采用柔性接口并增加接口强度和刚度、布设监测装置的工程措施。

Earth fissure is the typical urban geological hazard which may seriously jeopardize feed pipeline in Xi'an city.With Xi'an ductile iron feed pipeline crossing the earth fissure as an example,the full-scale model test on feed pipeline crossing earth fissure at an angle of 45°was carried out to study the deformation characteristics,structural stress and variations of earth pressure.The test results show that the pipeline at hanging wall may have differential settlement and the settlement at the end of the pipeline far from the earth fissure is the largest.The parts of the top and bottom of the feed pipeline at hanging wall may detach from the surrounding soils.The pipeline shows a complex overhanging beam mode.Vertically,the pipeline in hanging wall forms"concave downward"bending deformation,with a tensile zone at the top of the pipeline and a compression zone at the bottom of the pipeline.The pipeline in footwall forms"concave upward"bending deformation,with a compression zone at the top and a tension zone at the bottom of the pipeline.Horizontally,a tensile zone is formed on the acute angle side of the pipeline relative to earth fissure,and a compression zone is formed on the obtuse angle side.To a certain extent,the flexible T-joint of the pipeline can adjust the differential settlement of both sides of the pipeline,and the axial stress at the flexible joint is the largest.Hence,based on the model test results,some necessary engineering measures,including planning reasonable route,designing shallow buried or overhead pipline,adopting flexible joint,increasing the strength and stiffness of flexible joint and arranging monitoring equipment,are suggested.