黏土热–力学特性对能量桩力学特性的影响

能量桩运行会导致土体温度场的改变,从而影响桩周土的热–力学特性,进而影响能量桩的变形、桩–土界面应力及承载性能。将ACMEG-T土体热本构模型在ABAQUS软件中进行二次开发,通过编写UMAT子程序对能够反映黏土热–力耦合特性的三轴试验结果进行模拟与分析,验证了模型的可靠性。建立数值模型,研究了土体热–力学特性对能量桩位移、桩–土界面应力及桩身轴力的影响规律。研究结果表明,温度变化会导致土体产生累计沉降,并进一步导致桩侧产生负摩阻力;在负摩阻力的影响下,能量桩会产生额外的沉降以及不可恢复的轴力;土体热–力学特性对能量桩力学特性的影响效应随着土体超固结比的增加逐渐减弱。

Influences of thermo-mechanical properties of clay on mechanical responses of energy piles

Under the action of temperature variation induced by energy piles,the mechanical properties of soils surrounding the piles will be changed,thereby affecting their deformation,the stress of the pile-soil interface and the bearing capacity of the pile foundation.The ACMEG-T constitutive model for the thermal properties of soils is developed in ABAQUS commercial software.The accuracy of the program is verified by simulating the triaxial test results by using the UMAT subroutine.Based on the numerical simulation,the influence of thermo-mechanical properties of soils on the displacement of pile head,the stress of the pile-soil interface and the axial force of the energy piles in clay are studied.The results show that the change of soil temperature can lead to irretrievable settlement of soils,and further lead to negative skin friction on the pile shaft.The additional settlement and irreversible change of axial force of the energy piles can be induced by the negative skin friction.With the increase of the over-consolidation ratio of clay,the effects of thermo-mechanical properties of soils on the mechanical response of the energy piles decrease.