Study On Temperature Field Of Steel Tube Frozen Soil Composite Structure

At the present stage,rail transit and underground construction are increasing in our country.Artificial freezing method is widely used to reinforce and stop water in strata.However,the engineering environment faced by freezing method construction is becoming more and more complex.Urban rail transit engineering also encounters various kinds of difficult problems in construction,such as how to ensure the stability of the adjacent structures,how to ensure the safety of unstable foundation excavation and construction,and so on.Urban underground space is full of various structures,pipelines,roads and so on.How to effectively ensure the safe construction of underground and ground facilities is very important.In this paper,combined with the freezing construction of steel pipe frozen soil composite structure to be adopted in the actual project of Jiangpu Road Station of Shanghai Metro,the temperature field of steel pipe frozen soil composite structure is studied in two different layouts: double row pipe shed and hot water + pipe shed.In this paper,the development law of temperature field of steel pipe frozen soil composite structure is studied by finite element simulation and model experiment.In this paper,the theory,experiment and Simulation of freezing temperature field are systematically studied.Based on the latest research results of freezing temperature field of steel pipe-frozen soil composite structure and the calculation of freezing temperature field under the non-uniform numerical model developed by finite element software,the development law of limiting freezing temperature field under the arrangement of double-row pipe shed is obtained through the analysis of typical parameters.+ The rule of precisely controlling the development of freezing temperature field under the arrangement of pipe shed is obtained through single factor analysis.The development trend of temperature field under different freezing time is obtained by five factors: the diameter of pipe shed,thermal conductivity coefficient of filler,spacing between pipe shed,spacing between pipe shed and freezing pipe;the circulating hot water temperature and hot water pipe under the arrangement of hot water + pipe shed.The development trend of temperature field in different freezing time was analyzed by orthogonal test,and the influence of each factor on temperature field of composite structure of steel pipe frozen soil under two layout forms and significant analysis were obtained.Based on the similarity criterion,this paper designs a freezing experimental system with two layouts of pipe shed and hot water + pipe shed.According to this system,physical model experiments are carried out,and the influence of temperature field on the composite structure of steel pipe permafrost is discussed under the similar model experimental conditions.Comparing the calculated data from the model experiment with the finite element simulation data,the temperature field development law of the composite structure of steel pipefrozen soil obtained by the two research methods is basically the same.In physical test,the thickness of pipe shed wall is faster than that of soil,and the initial ground temperature is smaller than that of numerical simulation.The thickness and temperature of freezing wall in physical test are slightly larger than that of numerical simulation.The subject studied in this paper has certain guidance and reference value for the design and construction of reinforcement engineering which restricts the development of freezing.