基于能量法的尾矿土动孔压模型研究

Energy method for analyzing dynamic pore water pressure model for tailing soil

通过应力控制式动三轴不排水循环剪切试验,对饱和尾矿土在循环应力比、轴–径向固结应力比等因素下孔隙水压力与累积能量耗散关系进行研究。研究结果表明孔隙水压力增长与塑性应变累积能量耗散和土体黏滞累积能量耗散密切相关。当循环应力比cR介于0.205～0.238、轴–径向固结应力比cK介于1.0～1.3时,孔隙水压力–能量之间存在临界状态。通过非线性回归分析初步建立了循环应力比和轴–径向固结应力比条件下饱和尾矿土的孔隙水压力能量模型,从变化机理上阐述孔隙水压力的变化规律并消除了周次的不确定性对于孔隙水压力模型的影响,对预测循环荷载作用下饱和土的孔隙水压力具有借鉴意义。

By using the stress-controlled undrained dynamic triaxial cyclic shear tests, relationship between accumulative energy dissipation of tailing soil and pore water pressure is investigated based on the critical factors, namely, cyclic stress ratio and consolidation stress ratio. The test results indicate that, during the process of cyclic shear, the increase of pore water pressure is closely related to the accumulative energy dissipation of plastic strain and viscous properties. A critical state, when the cyclic stress ratio cR varies within the range of 0.205~0.238 and the consolidation stress ratio cK varies in 1.0~1.3, occurs between the pore water pressure and energy. Therefore, through nonlinear regression analysis, the energy model for pore water pressure of saturated tailing soil is preliminarily established based on the cyclic stress ratio and the axial-radial consolidation stress ratio, and it can be adequately employed to demonstrate the variations of pore water pressure without considering the uncertainty of cyclic loading number which can otherwise hinder the establishment of the model. In addition, the proposed model may also be a valuable source of reference for predicting the development of pore water pressure of saturated soil under cyclic loading.