Numerical Analysis Of The Thermo-mechanical Bearing Characteristics Of Geothermal Energy Pile

Geothermal energy pile, which equipped with the ground heat exchangers, act as energy production system of shallow geothermal energy. It is a suitable method to reduce carbon dioxide emissions, however, the thermo-mechanical bearing characteristics of geothermal energy pile are not clear, and it is not conducive to the application of geothermal energy pile. In this paper, numerical simulation is used to deepen the thermo-mechanical bearing characteristics of geothermal energy pile foundations and its influence factors, the main research results are as follows:1. The temperature change of the pile will result in the change of the friction and the axial force of the pile, the constraint of the pile end and the pile top structure have a prominent influence on the additional temperature load, the friction resistance and the axial force of the pile. The displacement effect of the geothermal energy pile caused by the temperature rise or drop is not obvious. The bearing capacity of geothermal pile must consider the influence of the load level and the ratio of length to diameter.2. During the long term operation process, due to the expansion and contraction of pile concrete the settlement of pile top present periodic change and could lead to increases at the same time, the cumulative effect of settlement of geothermal energy pile was related to the load level of geothermal energy pile; Under the same operating conditions, when the load level is low, the settlement accumulation increased with temperature cycles can be stabilized, when the load level is high, the settlement of pile top cumulative growth. The influence of temperature in the long term operation should be considered in application of geothermal energy pile.3. Due to the restriction of the raft the pile top counter force will be redistributed, the raft localized negative bending moment changed greatly. When the temperature of the geothermal energy pile raised, the top counter force of conventional pile will decreased, the top counter force of geothermal energy pile will increased, when the temperature of the geothermal energy pile reduced, the change of the top counter force of conventional pile and geothermal energy is contrary to the temperature raised.Combining with the results of numerical simulation, it is suggested that the effect of continuous periodic temperature variation on the pile settlement and the effects of different constraints on the internal force of pile should be considered in the design process of geothermal energy pile; When determining the distance of geothermal energy pile of raft foundation, it should not only considering the need for the heat transfer, but also considering the influence on the pile raft foundation structure performance.