Study On Temporal And Spatial Effect In Construction Of Large Span And Shallow-buried Tunnel

During the excavation of tunnel surrounding rock,it comes to some deformation which has a process of time and space,it was known as temporal and spatial effects. The paper take Tian Heng Shan tunnel of Harbin High-speed ring as the project background,studied temporal and spatial effects by the excavation of the large span and shallow-buried tunnel,on the bias of construction monitoring in the field,theory analysis and numerical simulation.Firstly the paper introduced the development and research of temporal and spatial effects' principles,briefly described the principles and steps of CRD method.Secondly according to the theory and situ measurement,analyzed the deep displacement of surrounding rock and ground surface settlement the excavation of tunnel,derived the principles of temporal and spatial effects.Finally,based on the practical engineering,a FEA software Ansys is used to carry on three-dimensional FEA,analyzed temporal and spatial effects during the excavation of tunnel.The following conclusions are summarized.1,The influence to deep displacement of surrounding rock of construction with CRD method can be divided 3 stages;Compared and summarized the change law of displacement gone with tunnel face during the excavation,Take function-Bolztmann carry on curve fitting and obtained good results.Defined the scope of surrounding rock loose circle,and there is reference to the value of engineering practice.2,The change process(temporal and spatial effects) of ground surface settlement can be generally divided the following stages,previous settlement stage,rapid change stages,slowly change stages and basically stable stages.The paper derived the evolution characteristics of surface settling tank and the revolution of ground surface settlement and tunnel depth is similar linear inverse relationship.3,Through the creation of three-dimensional elastic-plastic FEA model,the paper simulated tunnel excavation,analyzed the space effects and time effects on excavation face.Analyzed and compared the situ measured data and the numerical analysis data, verified the law of temporal and spatial effects.