Study On Horizontal Freezing And Frost Heaving Law Of Rectangular Channel In Muddy Clay Layer

Freezing method is often used in water rich soft soil area.In recent years,a large number of tunnels with rectangular section was excavated by freezing method.However,the frost heaving will cause uplift and deformation of the stratum,cause adverse effects,and even lead to engineering accidents,which limits the application.Therefore,it is very important to study the deformation law of rectangular channel and to control its deformation.Based on the project of a muddy soil underpass in Shanghai,this paper used the methods of mutual confirmation of theoretical analysis,numerical simulation and field measurement.The research results are as follows:(1)Based on the stochastic medium theory and the characteristics of rectangular frozen wall,the random medium prediction analysis of rectangular horizontal frozen formation deformation was established,and the calculation method was given.It can calculate the deformation of ground surface and overlying strata at any depth.At the same time,the sensitivity analysis of variables was carried out to determine the importance of each variable.(2)The numerical simulation method of thermal mechanical coupling of horizontal freezing in rectangular channel was established and applied to practical engineering.The laws of formation temperature field and displacement field in freezing construction were simulated,and the distribution laws of temperature field and displacement field were obtained.The theoretical prediction model and numerical simulation prediction results were compared with the actual monitoring values to verify the practicability and reliability of the prediction method.(3)Temperature and deformation were monitored.The development of frozen wall and the law of surface deformation were analyzed.The control technology of frost heave and borehole settlement was put forward,and the deformation in actual construction met the requirements.With the application of freezing method in underground entrance and other projects,the theory and method and deformation control technology in this paper will provide reference for the design and construction of these projects.