Study On Mechanical Characteristics Of Composite Structure Of Steel Tube And Frozen Soil

The pipe shed freezing method is a special construction technique that combines pipe shed support with artificial freezing.The pipe shed uses steel pipe as the longitudinal support and the steel grating arch as the lateral annular support,which constitutes the longitudinal and transverse overall stiffness,which can prevent and limit the deformation of the surrounding rock and soil,and can withstand the early rock and soil pressure in advance;artificial freezing and utilization Artificial refrigeration technology freezes water in the formation,turns natural rock into frozen soil,increases its strength and stability,and isolates the connection between groundwater and underground engineering.In some areas where the engineering geological conditions are relatively poor and the construction control requirements are high,the conventional pipe shed method will bring about the difficulty of controlling soil erosion and cause large land subsidence,and the freezing method will control the frost heaving during the freezing process.In this context,this paper proposes the study of the mechanical properties of the composite structure of steel tube frozen soil by physical test and numerical simulation.Firstly,the subject carried out a physical test of the shear strength of the contact surface of the steel tube frozen soil.The relationship between shear strength and temperature,normal stress,water content and outer diameter of the steel tube was studied by using a self-designed shearing device.The fitting formula.The test results show that the relationship between shear strength and normal stress is in accordance with the Mohr-Coulomb criterion,and the shear strength increases with the decrease of temperature and the increase of water content,and is almost unaffected by the outer diameter of the steel pipe.The effects of four factors on the shear strength of the contact surface of steel tube frozen soil were obtained by orthogonal test: temperature > water content > normal stress > outer diameter of steel tube.Secondly,the physical test of the steel tube composite structure beam and plate was carried out on the self-designed loading test rig.The test results show that the ultimate load of the beam is 38.9kN,and the failure form is the cracking of the bottom frozen soil;the ultimate load of the plate is 83 kN.The form of destruction is crushed by the top frozen soil.Through the monitoring of the section strain and the monitoring of the mid-span displacement,it is concluded that the combined structure of the frozen soil of the steel tube meets the flat section assumption and the displacement is small when the break is broken.Finally,with reference to the conclusion obtained from the shear test of the joint surface of the frozen steel soil,the numerical calculation model of the bending test of the composite structure of the frozen steel tube was established by ANSYS software.The calculation results were compared with the physical test data to verify the reliability of the numerical simulation.And the factors affecting the mechanical properties of the joint structure of the frozen steel tube were calculated and analyzed,and some relevant conclusions were obtained.This paper has 78 pictures,17 tables,and 83 references.