Model Test Study On Influence Of Tunnel Construction On Adjacent Stratum And Buried Pipeline Under Leakage Of Pipeline

According to statistics,most of the causes of urban land subsidence accidents are caused by leakage of pipelines.In this paper,taking the subway tunnel project of typical sand soil layer as the background,using the combination of model test and theoretical analysis,it takes full consideration of the seepage water range,the buried depth of the tunnel,the buried depth of the pipeline and the space position of the tunnel and pipeline,and changes the surrounding strata to the surrounding stratum under the seepage condition.And the influence of pipeline deformation is systematically studied.The main research contents and conclusions are as follows:First of all,the laboratory model test is carried out on the ground displacement caused by tunnel construction in sandy soil under the condition of pipeline leakage.The results show that,with the increase of water leakage in the pipeline,the deformation of the stratum shows a tendency to decrease first and then increase,and the maximum subsidence value of the surface is increased in the form of two functions.With the advance of the tunnel excavation,the settlement velocity along the depth of the depth of the strata increases gradually,and the maximum of the depth of the stratum is the largest in the depth of the stratum.The settlement velocity appears below the monitoring section,which is different from that of the monitoring section.The maximum settlement velocity of the curve appears at 0.75D in front of the monitoring section.According to the test results,the calculation formula of the width coefficient of the sink is corrected,and the calculation method for the loss of the stratum at any depth is established.Then,the indoor model test is carried out on the influence of tunnel shield construction on existing pipelines under the condition of water leakage.With the increase of the depth of the stratum,the settlement of the stratum increases first and then decreases with the increase of the depth of the stratum,and the maximum value of the settlement of the stratum gradually decreases with the increase of the range of the seepage area,and the occurrence range is within 1.5?2.5 times the pipe diameter above the top of the pipe.The displacement of the pipeline is less than the surface subsidence in the water leaking and leakage,and the displacement of the pipeline is analyzed with the surface settlement instead of the pipeline displacement.The result is Yu Anquan.When there is leakage,the displacement of the pipeline is greater than the surface settlement under the same condition.According to the test results,the relationship between pipeline displacement and ground settlement is established.Finally,based on the Pasternak foundation model,the two stage analysis method is adopted to establish the differential equation of the pipeline balance,and the simplified calculation of the pipeline displacement is realized.By taking the calculation method of the Pasternak foundation model under the seepage water effect,the results of the model test and the calculation method of the Winkler foundation model are compared.The results show that this method can be used to predict the vertical displacement of the pipeline caused by tunnel shield excavation under seepage water conditions.The results are of certain reference significance for guiding practical engineering construction.