Method for calculating axial force of energy pile under thermo-mechanical coupled function

Abstract

An energy pile is a novel efficient ground-source heat pump system. During structural design of the energy pile, the additional temperature stress caused by a temperature load needs to be considered. In order to solve the problem, the invention provides a method for calculating the axial internal force of the energy pile. According to the method for calculating the axial internal force of the energy pile, based on the energy pile temperature load deformation characteristic that the energy pile expands or shrinks with the neutral point as the bound and the characteristic that the magnitude of the temperature stress is determined by a restraint degree, combing the thought of a load transfer method with the characteristics, a one-dimensional finite difference calculation method for the pile under the thermo-mechanical coupled function is built. By the adoption of the method for calculating the axial internal force of the energy pile, the additional temperature stresses of the pile under the action of different temperature loads and the magnitude and the distribution of the internal force of a pile body under the thermo-mechanical coupled function can be calculated; and the influence of the temperature on the soil around the pile, the influence of pile-end soil on mechanical strength and the change of parameters of different soil layers are taken into consideration, and the influence of the superstructure type on the temperature stresses is also taken into consideration.

Description

technical field [0001] The invention relates to the technical field of a new technology for utilization of shallow geothermal energy—an energy underground structure, and in particular to a method for calculating axial internal force of an energy pile under thermal-mechanical coupling. Background technique [0002] The energy underground structure is a new technology that uses the underground permanent or temporary enclosure in contact with the formation to extract geothermal energy. This technology is to bury the heat exchange tubes in the underground structure without additional drilling. Compared with the traditional borehole buried pipe system, it has It has the advantages of low cost, good heat transfer performance, and no additional underground space occupation. The energy pile is a long and thin vertical underground structure, which can make full use of the underground constant temperature layer (shallow ground temperature energy has the highest utilization value), and...

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Problems solved by technology

[0003] However, due to the current lack of energy pile design specifications and reasonable internal force calculation methods in the world, the design mainly relies on experience and adopts the method of enlarging the safety factor. For example, Switzerland and the United Kingdom adopt safety factors of 3 and 3.5 respectively.

Obviously, this rough design method will lead to excessive pile foundation size and increase the cost, which will affect the popularization and application of this green building energy-saving technology

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