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冻土与构筑物基础接触面的本构模型是分析冻土区构筑物与冻土相互作用、评价工程安全稳定性的基础和关键.为了降低切向冻胀力对基础的上拔作用,防止发生冻拔失稳破坏,青海-西藏±400 k V直流联网工程基础广泛采用玻璃钢覆盖基础表面,以消减冻胀力.为了合理描述玻璃钢与冻土接触面力学特性,采用应变直剪仪开展了青藏冻结粉土与玻璃钢基础接触面直剪试验,获取了不同冻结温度条件下接触面剪应力-位移曲线,分析总结了接触面的强度变化规律和受力变形特性,基于试验得到的接触面本构规律建立了耦合温度效应的冻结粉土与玻璃钢基础接触面剪切应力-位移关系.模型预测结果与试验结果的比较表明,预测结果与试验结果吻合良好,该模型能够较好的描述接触面的力学特性.
The constitutive model of the contact surface between the permafrost and the foundation is the basis and key to analyze the interaction between the permafrost structure and the frozen soil and evaluate the safety and stability of the project.In order to reduce the effect of tangential frost heaving on the foundation and prevent the occurrence of freezing Qinghai-Tibet ± 400 kV DC network based on the extensive coverage of the basic surface of glass fiber reinforced plastic to cover the foundation to reduce the frost heave force.In order to reasonably describe the mechanical properties of FRP and frozen soil contact surface, the use of strain-shear device to carry out the Qinghai-Tibet freeze The shear stress-displacement curve of contact surface under different freezing temperatures was obtained by direct shear test on the contact surface of silty soil and FRP steel. The strength variation and the deformation of contact surface were analyzed and summarized. Based on the constitutive law of contact surface The shear stress-displacement relationship between frozen silt and FRP was established based on the coupled temperature effect.The comparison between model predictions and experimental results shows that the predicted results are in good agreement with the experimental results and the model can well describe the mechanics of the interface characteristic.