Study On The Buried Pipeline-Soil Interaction And Its Mechanical Response By Mining Subsidence

More and more buried pipelines will be affected by mining subsidence because of the increasing mining areas and the development of pipeline transport in China, so it is a difficult problem which should be studied urgently for the normal operation of buried pipelines induced by coal mining. Research on pipe-soil interaction mechanism and mechanical response of buried pipelines are the basis of safety assessment for buried pipelines, and it is important to the safety prediction of buried pipelines. In this dissertation, systematic research on pipe-soil interaction mechanism and mechanical response of buried pipelines in the mining subsidence soil has been done by experimental study, theoretical analysis and numerical simulation. The major innovative achievements are outlined as follows.(1) Test equipment and system for pipe-soil interaction research in mining subsidence soil have been developed. The test system includes model making system, deformation control system for soil induced by subsidence, deformation monitoring system for soil and buried pipeline, earth pressure around the pipe and pipe strain monitoring system. This test system can monitor the deformation and stress of soil and pipeline induced by mining subsidence and pipe-soil mechanics parameters, and it can provide evidence for study of pipe-soil interaction mechanism.(2) The pipe-soil deformation, pressure around the pipe, pipe axial strain and soil deformation above pipeline are determined in different soils by test system for pipe-soil interaction. The distribution laws of pipe-soil deformation, pressure around the pipe and strain along pipeline have been obtained. It reveals the pipe-soil coordinating deformation relations, the characteristics of soil break and binding force around buried pipeline in the test.(3) Numerical analysis model of mechanical response of buried pipelines in the mining subsidence soil is established. Pipe-soil coordinating deformation and distribution of additional axial stress during evolution of subsidence have been simulated. Influence laws of pipeline depth, soil mechanics parameters to mechanical response of buried pipelines are revealed.(4) Based on probability integral method, the surface deformation laws along pipeline and its prediction formulas induced by mining are derived, and pipe-soil cooperative deformation conditions in mining subsidence are established. Based on the pipe-soil deformation relations, pipe-soil coordinating and non-coordinating mechanical model are established respectively. The calculation of additional stress and mechanical response of buried pipeline are proposed. The analysis program of buried pipeline mechanical response induced by the mining subsidence is put forward.(5) According to mining geological conditions of a mining working face, similar simulation test is conducted to predict the deformation of surface along pipeline with the mining working face advance. The distribution law for strain of buried pipeline induced by mining subsidence is obtained, and safety assessment for buried pipeline is carried out.The results can be treated as an important basis for analysis mechanical response and safety assessment of buried pipeline in the mining subsidence.