Study On Stress And Deformation Regularity Of Frozen Wall In Offshore Seabed Shield

Due to the adverse geological influence during the construction of the shield tunneling machine in the submarine section of Xia Men Metro Line 3,the cutter head and the knife box were worn and the shield was trapped and stopped.The solution to the problem is to use a two-way staged artificial ground freezing method,which is used to repair the working chamber in front of the cutter head,repair the knife box and replace the tool.Based on the results of the freezing and unblocking project of the submarine shield tunnel of Xiamen Metro Line 3,based on the results of thermal physics and mechanics test of offshore frozen soil,the numerical simulation and physical model test are used to conduct research.After data analysis and comprehensive comparison,the conclusion is drawn..Firstly,the on-site sampling of the submarine shield freezing and relief project of Xiamen Metro Line 3 was carried out,and the physical and mechanical parameters of frozen soil were tested in three offshore soil samples to obtain compressive strength,elastic modulus,Poisson’s ratio and flexural resistance of offshore frozen soil.Parameters such as strength,icing temperature and thermal conductivity are used as the basis for the material parameters of subsequent numerical simulations and physical model tests.Secondly,the typical parameter calculation,single factor test and orthogonal test are carried out by numerical simulation analysis.In the calculation of typical parameters,the appropriate parameters are selected to calculate and analyze the two-way staged freezing temperature field and the frozen wall excavation construction,and the temperature field,displacement field and stress field variation law of the frozen wall are obtained.In the single factor experiment,the effects of freezing initial ground temperature,tunnel depth,tunnel diameter,excavation step distance and surface load on the displacement field and force field of the frozen wall are studied.In the orthogonal experiment,the influence of the above factors on the temperature field development and displacement law of the frozen wall is obtained.Thirdly,taking the actual project as the prototype,the model is simplified as necessary,and the physical simulation test is carried out according to the similarity theory.Self-research and design of two-way staged frozen tunnel excavation simulation system,obtain and analysis the date of temperature field and displacement field.Finally,the results of two type test are compared and analyzed.The results show that the laws obtained by the two research methods can be mutually verified.The conclusions obtained in this paper have certain reference value.