Study On Mechanism Of Frost Heaving And Thaw Settlement In Construction Of Tunnel-channel Freezing Method

Artificial freezing soil technique is a well-proven soil improvement approach used worldwide to construct shafts,tunnels and many other civil structures in difficult subsoil or ambient conditions.we present quantitatively the mechanism and analyze results from the monitoring of applications of artificial ground freezing in tunnel construction projects.This thesis considers the thawing process related to the settlement in fine-grained soils and describes the artificial freezing and thawing process,identifying differences and similarities with natural freezing.It also describes how different soil and rock parameters influence deformations and stresses during freezing and thawing in artificially frozen constructions.These descriptions are primarily based upon literature studies and case studies.The first case study concerns the construction of a twin tunnel for the Jiangyu road station subway in Binjiang district,Hangzhou city,Zhejiang province in china with soft soil with significant seepage flow.The emphasis of this study was on a realistic simulation of the overall project situation during the frozen body growth stage.The second case study relates to a platform tunnel in a station of Hangzhou City Rail Transit Line 5 Line 16 Standard Jiangnan Avenue Station-Jianghong Road West Station Zone 1metro with the aims to determine missing but relevant material parameters via back analysis and the mechanism prediction is compared with the field measured results.The construction was greatly delayed due to the failure to form a completely closed frozen body.Field monitoring activities to enhance our understanding of the mechanical integrity of freeze wall containment system will also be briefly introduced and the simulation has been performed via coupled analysis by JOBFEM...