Study On The Failure Mechanism Of Bell-and-Spigot Water Pipelines Under Differential Settlements

With the vigorous development of China’s economy in recent years,people’s demand for water resources is also increasing day by day.As a means of transportation of water resources,water supply pipeline plays a vital role in urban production and life.However,in recent years,the common site differential settlement accident has brought great harm to the buried water supply pipeline and seriously affected the production and life of the city.In this paper,the failure mechanism of socket ductile iron water supply pipeline is studied by using numerical simulation and theoretical method.The main research contents include the following parts:(1)Analyzed and completed the determination of typical loads including buried pipelines,mathematical analysis models and structural failure indicators.The basic theoretical basis of pipeline numerical simulation analysis was established.Relying on the finite element analysis software,the key technologies,including configuration of structural attribute parameters,finite element model optimization,pipe-soil interaction and load application method,were determined,and the finite element model of buried pipeline was established.(2)Based on the finite element model,the stress analysis of the socket water supply pipeline under operation and environmental load was carried out.The stress variation law of the socket type water supply pipeline under the action of different intensity water hammer was explored.The differences of mechanical responses of the sock-and-socket water supply pipeline were compared when the vehicle load acted on the pipe and the interface respectively.The structural response characteristics of socket water supply pipeline under typical load were obtained.(3)On the basis of operation and environmental load,the structural response of the differential settlement acting on the pipe and interface of the socket water supply pipeline was studied.Also,the stress characteristics of pipes with different diameters under the action of differential settlement were obtained.The influence law of pipe settlement length and amount on pipe stress and deformation was summarized and the variation law of mechanical response of socket water supply pipeline with different elastic modulus of soil was compared.(4)By combining the typical load action and differential settlement action,the failure mechanism of water supply pipeline under the combined action of differential settlement load was studied.The synergistic relationship between pipe and soil deformation in the process of soil settlement was simulated and analyzed.Meanwhile,the influence of pipe diameter and pipe settlement length on the failure mode was analyzed,and the critical settlement length of pipeline failure due to differential settlement was proposed.(5)Based on the force calculation model of suspended buried pipelines and the assumption that the socket pipe interface was hinged,lowest limit of critical settlement length for the failure of pipelines of different diameters due to differential settlement was deduced,and the failure modes of pipelines of different diameters obtained by simulation were verified.In this paper,the structural response and failure mode of the sock-type water supply pipeline under the action of differential settlement were analyzed in detail by means of numerical simulation and theory,and the results provide a certain basis for the mechanical response analysis and safety evaluation of the sock-type water supply pipeline under the action of differential settlement in a small range of sites.