Experimental Study On Friction And Sliding Characteristics Of Pipe And Soil Interface

The nodular cast iron pipe with rubber interface is widely used in urban infrastructure construction,and is an important part of urban pipe network.Geological disasters such as earthquakes can cause serious damage to buried pipelines.Axial friction resistance is an important parameter in seismic design of buried pipelines,which has a great influence on displacement transfer coefficient on pipe axial direction.In view of this,related test items relying on the pipeline stress under earthquake was designed tosimulate mechanical properties of pipeline interface and axial friction resistance.The experiment studyincludethree parts.Part oneis the test on apron pipeline under cover soil condition.Firstly socket interface pipelinebell pipe was fixed,pulling and pushing the spigot pipe in the axial direction repeatedly.Then releasing bell pipe constraint,pull and push the spigot pipe.Part two is pulling and pushingspigot pipe and bell pipe respectively.In the program of the experiment,the factors which affect the axial friction of the soil are studied by changing the depth,the length and the loading rate.Part three is pulling and pushing the spigot pipe in the axial direction repeatedly with socket interface pipeline bell pipe fixed under no soil condition.It is found that the axial resistance of pipe soil has a positive correlation relationshipwith the buried depth and loading rate,and approximately has a linear relationship with buried length.During the initial stage of loading,the force and displacement curves of pipeline are linear elastic,and in the next stage of loading,for the spigot pipe,the slope of the force and displacement curves of the pipeline decreases and the frictional resistance is still increasing.There is no peak.For spigot pipe,it shows a decreasing trend,when the friction resistance reaches the peak value.The axial frictional resistance of pipe soil is calculated by theoretical formula,and the results are compared with the experimental results.It showed that the soil density,buried depth,pipe diameter,pipe-soil friction coefficient are critical factors affecting pipe-soil axial resistance through the numerical model analysis.And these factors have a positive correlation relationship with the axial resistance,also the axial stress of pipeline increases along the load direction.In this paper,three kinds of research methods,such as experimental study,theoretical analysis and numerical model analysis,were used to analyze and study the mechanical properties of the apron and the axial friction of the pipe,and reach the corresponding conclusions which has a certain reference value for the seismic design of pipeline.