Research On Pipeline Deformation Caused By Tunnel Construction And Safety Risk Assessment

The development of underground tunnel traffic has become an important indicator of the city’s comprehensive development strength.The large-scale development of the tunnel project will inevitably disturb the surrounding strata,and the municipal pipeline network that has been formed inside it will also be destroyed under the movement of the stratum,which brings many problems to residents’ lives,urban operation and underground engineering construction.Therefore,it is an important engineering research topic to explore the deformation mechanism,influencing factors,pipeline risk assessment and subsequent pipeline reinforcement and protection of adjacent pipelines during the construction of tunnel projects.This article takes buried pipelines disturbed by tunnel construction as the research object.Through designing indoor model tests,establishing numerical model simulations,and evaluating pipeline safety risk status,the pipeline deformation mechanism during tunnel excavation and the influence of pipelines under various control factors are studied.The main contents are as follows:First,a brief introduction to the classification,stress status,common damage forms,parameter control standards and engineering monitoring methods of urban municipal pipelines.Then design the indoor model test,select the pipeline burial depth,pipe-tunnel angle,and fill material as the control factors to design multiple sets of control test conditions.The test results show that,with the increase of the buried depth,the settlement of the pipeline is increasing;The settlement process of orthogonal pipelines and parallel pipelines is quite different,and the final settlement of parallel pipelines is slightly larger than that of orthogonal pipelines;The increase of the cohesion of the filling materials has reduced the settlement,settlement rate and final settlement of each stage of the pipeline.Secondly,the FLAC3D numerical software was used to simulate the pipeline deformation process during the tunnel construction process,and the pipelines under different working conditions were simulated with the influence of pipeline presence,pipeline-tunnel angle,pipeline buried depth,pipeline lateral distance,and tunnel excavation depth Deformation law.The simulation results show that the settlement process of the pipeline will go through three periods successively,and the settlement mainly occurs during the disturbance period of shield excavation.Compared with the non-pipeline condition,due to the support of the pipeline,the stratum movement and tunnel section deformation will be reduced to varying degrees.The settlement of the pipeline will have different deformation rules due to the changes of various influencing factors.Finally,on the basis of numerical simulation,the settlement value and the inclination value are selected as the pipeline parameter control standards,and the pipeline is divided into four safety risk status levels.When the settlement value is used as the control standard,the boundary of the safety risk level range of parallel pipelines and orthogonal pipelines is extended in a long circular arc to the upper stratum;When the inclination value is used as the control standard,the boundary of the safety risk level range of the orthogonal pipeline extends upward in the shape of butterfly wings.The distribution of the destruction zone under the two parameter standards is quite different.Two judgment methods need to be taken into account when judging the pipeline safety risk level,and the more serious of the two should be taken as the pipeline safety risk state.