Analysis Of Ground Surface Deformation Caused By CRD Method In Railway Tunnel And Its Influence On Structures Nearby

With the increasing urban traffic and people's awareness of environmental protection,the metro hiddenexcavationhas been gradually replaced by open-cut method and widely used in the metro construction.As a hiddenexcavation method,shallow-buried tunneling method is applied widely because of its obvious advantages,such as the low cost,less demolition and little interference withground transportation etc..However,the tunnel construction by shallow-buried method inevitably disturbs the underground soil,breaking the original state of equilibrium,and makes the soil incline to a new balanced state.During this process,the underground soil and ground surface will displace and settle.When the displacement and settlement reaches a certain degree,the ground surface will seriously subside and collapse,which damages the ground building and underground pipelinesfurther.Theseproblems affect people's normal life seriously,and bring social adverse impact.Based on the Line 7 of Chengdu Metro,according to the analysis of ground surface displacement induced by shallow buried tunnel construction and its effects to buildings,combining on-the-spot monitoring and measurement data,the thesis obtains the regular pattern of the ground surface deformation and the relations of construction settlement in each step during the four-step CRD construction,as well as the safety impacton underground pipelines.The main researches are as follows:(1)A literature review of the surface settlement caused by Metro construction and combining Jinsha Museum Station Projects of Chengdu MetroLine 7,the thesis introduces construction measures and processes of the CRD construction.(2)In order to avoid the adverse influence on buildings,relic,cultural relics and vegetations in the Jinsha Site Museum,the impact on the security of Jinsha Ruins area is evaluated and the zone of influence caused by construction is obtained.(3)In consideration ofconstruction procedure and time-space effect,the process of CRD construction is simulatedbymeans of 3D-FDM andthe regular laws of the ground surface deformation,pipelines deformation and the relations of construction settlement in each step are analyzed.(4)Based on monitoring data,the field monitoringcontent and project are introduced,and the influence on ground surface deformation and pipelines caused by CRD construction is analyzed.