Simulation Analysis On Freezing Construction Of Beijing Subway Connecting Passage

In the subway,the existence of connecting passage plays a very important role.The setting of the liaison passage makes it possible for the passengers to quickly transfer the underground vehicle to another safe tunnel through the liaison passage and quickly evacuate to the ground in case of sudden natural disasters such as fire,water gushing and collapse in a tunnel during the operation of the subway.Besides,it can also be used by professionals for emergency rescue.The research content of this paper is based on the construction project of 2#connecting passage in Xinfadi Caoqiao station shield interval of Beijing Metro Line19 phase I civil engineering 08 contract section.It studies the change law of temperature field and displacement field in the construction area of connecting passage under the freezing method construction,which does not provide a certain reference value for similar underground construction in the future.In the research process,the numerical simulation method is used to build the underground construction model which is consistent with the actual situation,and the relevant parameters are consulted to simulate the changes of heat conduction temperature field and thermal stress displacement field after 50 days of active freezing.Combined with the field monitoring and relevant theoretical analysis,the influence of freezing method on the temperature and settlement of the stratum is studied,The main research contents are as follows:(1)Referring to the relevant literature and collecting the parameters of the stratum where the freezing construction of the connecting passage is located,the Abaqus software is used to build the stratum model which is consistent with the actual situation.According to the construction scheme,the tunnels formed by the shield and the freezing pipes with different positions are arranged at the corresponding positions of the stratum.The change of heat conduction temperature field after active freezing for 50 days is preliminarily simulated,and the corresponding temperature law is found out.(2)Using the same operation model,change the relevant attribute settings of the formation,add the results of the previous temperature field simulation as the premise to this operation,simulate the further change of thermal stress displacement field,and deduce the corresponding displacement law.(3)with the purpose of analyze the feasibility of the numerical simulation results,the measured data of temperature field and displacement field in each period are extracted and compared with the corresponding temperature measurement hole temperature data and surface settlement displacement monitoring data in the actual monitoring process.(4)On the premise of the above conclusion,change the soil saturation,simulate the change law of heat conduction temperature field and thermal stress displacement field when the saturation of pebble gravel layer is 100%,85%,70% and55%,and get the final conclusion.