不同应力条件下砾石土防渗料和反滤料联合抗渗试验研究

Filter tests on gravelly soil and filter material under different stress states

利用自行研制的可提供高水压、高应力的粗粒土大型高压渗透仪,对双江口砾石土心墙堆石坝防渗料和反滤料进行了联合抗渗试验,研究不同应力状态下防渗料和反滤料的渗透变形特性。结果表明:(1)单向压缩条件下,防渗料的渗透系数随应力的增加而减小,且渗流稳定时的渗透系数与应力的关系满足Louis负指数方程;试样发生破坏的临界坡降随应力的增加而增大。(2)水平加荷、竖向自由变形条件下,试样的渗透系数随水平应力的增加先减小后增大。试样发生破坏的临界坡降随水平应力的增加先增大后减小。在达到峰值之前,反滤料越松或越细,临界坡降随水平应力增大的幅度越大;在达到峰值之后,反滤料越密或越细,临界坡降随应力减小的幅度越大。

Filter tests on gravelly soil and a filter material under different stress states are conducted using a new large permeameter. The results show that： （1） In the case of confined compression, the permeability of the gravelly soil exhibits a negative exponential relationship with the increasing of compressive stress, which is consistent with a commonly used empirical relation. The critical hydraulic gradient of the gravelly soils increases nonlinearly with the increasing of compressive stress. （2） In the case of horizontal compression and free vertical deformation, the permeability of the soil sample decreases and reaches a minimum, then increases with increasing stress. The critical hydraulic gradient increases and reaches a maximum, then decreases with increasing stress. Before the peak, the critical hydraulic gradient of the soil sample with looser or finer filter increases more significantly with the increasing horizontal stress. After the peak, the critical hydraulic gradient of the soil sample with denser or finer filter decreases more quickly with the increasing horizontal stress.