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

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. © 2023 Editorial Office of China Civil Engineering Journal. All rights reserved.