地裂缝活动对地下输水管道影响的足尺模型试验

Full-scale model test on behaviors of urban underground water delivery pipeline crossing active ground fissure zone

地裂缝是西安市最典型的城市地质灾害,对地下管道造成了严重的危害。以西安市地下输水(排污)管道穿越地裂缝为背景,在地裂缝对地下管道危害分析的基础上,通过地裂缝活动对地下管道影响的足尺模型试验,研究地裂缝作用下地下管道的受力情况、变形和破坏模式。试验结果表明:在地裂缝作用下,无论是骑缝式还是对缝式敷设地下管道受力较为复杂,管道处于拉压受力状态,其变形破坏模式大致可以分为2类即骑缝时反向弯曲的弹性地基梁破坏模式和对缝时端部上翘的悬臂梁破坏模式;管道开裂破坏的地裂缝位错量临界值为S_(cr)=6 cm;骑缝式管道开裂破坏位置主要位于下盘靠近地裂缝0.5 m范围内,而对缝式管道开裂破坏位置主要位于上盘距地裂缝1.2 m附近以及接头部位。基于模型试验结果,提出地裂缝发育区管道工程建设应采取避让和合理规划管线走向,对跨越地裂缝带的管道工程需采取管沟浅埋或悬空式架设、柔性管材及接头加固、地下廊道铺设以及监测预警等防治措施。研究结果对于西安市城市管网建设与跨越地裂缝带的老旧管网改造具有重要的指导意义,对其他地裂缝发育区管道工程建设亦具有参考与借鉴价值。

Ground fissure is the most typical geological disaster which has endangered the safe use of underground pipes in Xi ＇an city. Based on the analysis of the harm on model test was carried out to study the force condition, underground pipes induced by ground fissure, full-scale deformation and failure modes of underground pipeline crossing the active ground fissure. The model test results show that whichever layout mode of underground pipeline is （riding or joint riding across ground fissure）, the stress on the pipeline is sophisticated and pipeline is in tension and compression simultaneously. The deformation and failure modes of pipeline can be divided into two kinds that one is reverse bending-elastic foundation beam failure mode, the other is terminal warping-cantilever beam failure mode. The critical value of ground fissure dislocation leading to crack failure of underground pipeline is 6cm. For pipeline riding across ground fissure, cracks mainly appear in the range of 0.5 m from the position of ground fissure at foot wall. As to pipeline with joints riding across ground fissure, cracks mainly appear at the spot with a distance of 1.2 m from ground fissure at the hanging wall. So keeping a certain distance from the ground fissures and reasonable planning should be adopted for the underground pipeline construction in ground fissure developed areas. As for underground pipelines crossing the ground fissures, the necessary countermeasures such as shallow buried pipe ditch, overhead setup, flexible pipes, joint reinforcement, underground corridor and monitoring and early warning etc. should be taken to avoid and prevent the crack failure of pipelines induced by active ground fissure. The conclusions can be presented as the reference to plan of new pipeline network and old network reconstruction in Xi＇an city and also to pipeline engineering construction of other developed areas of ground fissures.