Research On Impermeability And Durability Evolution Of Segment Joint Of Shield Tunnel

As a major infrastructure construction urban rail transit system usually constructed in underground environment and has characteristics of long design life, miscellaneous service environment, poor maintainability and high maintenance costs. As Shield Tunnel has been widely used, it’s joints are not only the important parts for the lining segments connecting but also the weak link for durability. Segment joint prominent problems can bring very significant impact on the overall durability of the tunnel.This paper relies on the National Basic Research Program (973) Underground structural performance evolution of urban rail transit system and basic theory of sensing and controlling and other topics, combined with the actual situation of Changsha subway tunnels, theoretical analysis, experiment and numerical simulation have been used to analysis the problem of performance evolution of tunnel lining joint in the underground environment.(1) Summarizes the common factors which affect lining joints in external environment, and analysis the lining joint durability issues from both material and structural. At last, put forward impermeability as an indicator of durability evaluation criteria.(2) Take joint service environment into consideration, completed the accelerated aging test of EPDM which is used as waterproof material of the joint lining under groundwater environment, obtain performance deterioration rules of rubber material under water environment. Put forward variable evolutionary model of waterproof material as a basis for analysis performance degradation rules of hyper-elastic material parameters.(3) Design segment joint impermeability test equipment, completed joint impermeability test under a variety of contact state, focusing on its flow variation after joint seepage has been occurred. Put forward a joint stress-seepage coupling model which consider the joint seepage as plane slit seepage problem. At last the contact interface stress-seepage coupled equation is derived out which is treated as the basis for joint analyzing of relationship between deformation and seepage problems.(4) The joint lining stress relaxation evolution model and three dimensional multi scale shield tunnel hybrid model have been established separately in both local and global level by using numerical simulation tools, and also lead the variable evolution model of waterproof material into consideration to calculate the contact pressure changes and trends of structure in service period. Then combined with the contact boundary stress-seepage coupling equation, the durability of evolution of lining joints in its whole life cycle has been obtained. At last put forward the proposals about lining joint maintenance according to the results of calculation.(5) Shield tunneling through three dimensional multi scale hybrid model gives a case of tunnel serving to analyze lining joints durability evolution and life prediction under different external water pressure. Draw the joint of the lining life assessment maps, and treat it as the basis to assess the prediction life which meet durability requirements under normal external water pressure.