Study On Force Mechanism Of Energy Group Piles Under Temperature-stress Coupling

With the development of our country's economy,the theme of energy conservation and environmental protection has been promoted,and the application of energy piles in construction projects is increasing.The energy pile is a geothermal utilization device that embeds heat transfer tubes in cast-in-place reinforced concrete piles and uses heat transfer tubes for heat transfer and conversion.As the temperature is transmitted through the pile,the temperature inside the pile will rise or fall,and a certain temperature stress will be generated in the pile.The generation of temperature stress will change the structural stability of the pile,and the settlement value of the pile will have a certain change,which is unfavorable to the overall structure of the building.At the same time,the use of pile group foundations is also increasing,so it is necessary to carry out research on energy group piles and numerical calculations,and it has certain reference value for the use of energy group piles for super-large buildings and structures.In this paper,by understanding the research status of energy piles and group piles at home and abroad,the factors of thermal conductivity,initial conditions and boundary conditions are introduced.The finite element theoretical calculations of steady-state temperature field and temperature stress are analyzed.The group pile foundation under vertical load is also introduced.The theoretical analysis of the bearing capacity and settlement will discuss the settlement of piles under the action of group piles.By referring to the actual measured data of the completed projects and using the ANSYS workbench and fluent software to perform the thermal-solid-fluid coupling simulation analysis,the temperature distribution of the temperature field and the stress field of the energy pile after temperature cycling,the temperature stress cloud diagram and the settlement of the pile were analyzed.Figure,and calculate the axial force distribution of the pile by software.Combining with the existing data,the actual temperature measurement results of the inlet and outlet after the energy pile temperature cycle is stable are obtained.The error at 5°C is 0.54°C and the error at 50°C is 1.59°C.At the same time,the energy pile settlement is measured under the temperature cycle.The comparison between the values and the simulation results shows that the unapplied temperature is 0.42 mm,the error is 0.14 mm at 5°C,and the error is 0.47 mm at 50°C.It is considered that the reliability of simulation analysis using ANSYS is higher.Based on the energy single pile,the energy group pile simulation was carried out to analyze the temperature field distribution of the energy group piles and the force condition of the pile body.By comparing the energy single pile and the energy group pile results,it is concluded that the group pile and single pile settlement value is 2.44 mm when the temperature is not applied,a 3.68 mm difference at 5°C,and a 2.18 mm difference at 50°C.It can be concluded that the pile group is in each The change of settlement under the effect of temperature increases,which proves that the effect of the pile group under temperature is even more negligible,and provides corresponding suggestions for the application of energy group piles in the construction project.Finally,the main research focuses and conclusions of this paper are summarized,and the application of energy pile and pile group in engineering is forecasted.