Numerical Simulations For Freezing Method In Connecting Channel Excavation Of Nanchang Subway

Nanchang Subway is located on the impact plain of the Gan River.The top layer of the soil distribution is plain fill,silty sand,medium sand,coarse sand,round gravel,and some moderately weathered rock formations.The excavation layer is mainly saturated sand with high water content.The soil is predominant,so an artificial freezing method was used during the construction of the communication channel.This article relies on the engineering background of the Nantong Subway Line 1,Normal University South Road Station to Pengjiaqiao Station Interconnection Channel.Take the sand on the spot to prepare saturated sand samples with density of 65%,70,75%,and 80%,and obtain the corresponding freezing temperatures and temperatures of 10?,5?,2?,1?,and 0?,and specific heat,frost heaving,and thawing coefficient at-1?,-2?,-5?,and-10?.Using finite element analysis software ABAQUS and establish corresponding numerical model,it is concluded that freezing temperature,freezing time,freezing temperature field,frost heave and thawing settlement displacement and segment stress and thawing period 30 th days,60 th days,90 th and 120 th days of temperature field.Comparison with on-site monitoring data verified that the model is in line with reality.Analyze the brine temperature at-25? and-30? and-35?,positively freeze the temperature field on the 10 th,20th,30 th,40th,and 50 th days and freeze the wall thickness with different designs to achieve the required strength The required freezing time gives the change law of the soil temperature field and frozen wall thickness with the change of brine temperature and freezing days.The climate change of the four seasons in Nanchang is relatively large,and the temperature field,displacement field and segment stress during the construction of the frozen season in different seasons are simulated.At the same time,the effect of groundwater flow on the freezing effect is considered,and the temperature field and the temperature of the freezing wall vary with time and the stress of the pipe is simulated.It is concluded that the greater the fluidity of groundwater is,the greater the temperature loss will be and the frozen wall will take longer to reach the design strength.