粗粒土渗透损伤特性试验研究

Experiment on the seepage damage coarse grain soil

为深入认识渗透变形对粗粒土渗透性及压缩性的影响,利用自主研发的加载式大型渗透变形仪对不同级配的粗粒土试样进行渗透变形全过程试验及侧限压缩对比试验,获得了不同试件产生渗透变形的临界水力梯度、渗透系数演化规律及损伤变化特性。研究成果表明:渗透变形过程中渗流路径中下游部位产生了渗透挤密效应,引起局部渗透性降低;在后期增加的水头作用下,先前产生渗透挤密部位的渗透性逐渐增大。试样产生渗透变形后,压缩模量减小;颗粒级配不同,渗透破坏引起的压缩损伤程度亦不相同。试件产生渗透变形后,在重力和渗透力作用下,试件结构将产生重构现象。

To explore the influence of seepage deformation on the permeability and compressibility of coarse grain soil, the whole process of seepage failure and compression experiment with lateral confinement on coarse grain soils with different gradations were conducted using seepage failure instrument developed by the authors. The critical hydraulic gradient, evolution law of permeability coefficient and damaged characteristics were obtained through analyzing the measured data and observed phenomenon during the test process. The results indicate that the seepage extrusion effect will generate firstly at the location of downstream along seepage path during seepage failure process and induce decrease of the permeability at the location. The permeability of the seepage extrusion part increases gradually with the increment of the experiment water head. The compression modulus of samples decreases after the seepage failure occurred. The degree of damage of the sample due to seepage failure is different on different grading samples. For soil samples after seepage failure, the structure of soil samples is reconstructed under the influence of gravity and seepage force.