Study On The Evolution Law Of Freezing Temperature Field At The Interface Of Connecting Passage In Sand Gravel Stratum

With the continuous development of subway construction in China,artificial freezing method is also more and more used in the construction of contact passage in various complex terrain.In the current freezing method construction liaison passage,the freezing effect of the interface between segments and soil leads to a series of safety accidents.Especially in the humid and hot environment and flowing water conditions,how to ensure the freezing effect of the interface during construction is an urgent problem to be solved.Based on the construction project of freezing method of 1 connecting channel between the central station and Olympic sports station of Hangzhou Metro Line 7,combined with numerical simulation and physical test,the development law of freezing temperature field of the interface before and after the excavation of the connecting channel is systematically studied.First,the numerical simulation is carried out by COMSOL software.The development law of freezing temperature field of the interface before and after the excavation of the connecting channel is obtained by the calculation of typical parameters;the influence of seepage velocity,air humidity,air temperature,wind speed in tunnel and wind speed in the tunnel on the freezing temperature field of the interface is studied through single factor test;the influence of various factors on the freezing temperature field of the interface of the connecting channel is obtained through the positive intersection test;the freezing temperature field of the interface is obtained by the back circuit test The quantitative relationship between the freezing thickness and average temperature of the interface before excavation and seepage velocity,air temperature and wind speed in tunnel is obtained by the analysis of the normalized intersection.Secondly,physical simulation experiment is carried out.According to the similarity theory,the freezing and excavation model test system is designed to simulate the freezing and excavation process of the actual connecting passage.Because it is the most unfavorable condition of freezing after complete excavation,in order to simplify the calculation,one-time excavation is carried out during the test,and the excavation part is ventilated.By laying temperature sensors in the test soil,the temperature data of each characteristic path is obtained,and the development law of freezing temperature field before and after excavation of the interface of connecting channel is analyzed.Finally,through the comparison of the temperature change of the measuring points,the temperature distribution of the characteristic path,the freezing thickness and the average temperature under the two research methods of numerical simulation and model test,the consistency of the development law of the freezing temperature field at the interface under the two research methods is verified,and the evolution law of the freezing temperature field at the interface of the connecting channel is obtained,Provide guidance for the follow-up research and engineering construction.There are 58 figures and 20 tables as well as 61 references in the paper.