Internal erosion can be a cause of failure in hydraulic structures such as levees, dikes and embankment dams. Suffusion is a type of internal erosion in which the fine particles migrate through the voids between the coarse particles under seepage flow, leaving behind the coarse skeleton. In this study the impacts of suffusion on the mechanical properties of soil in triaxial compression and torsional shear were investigated using a gap-graded soil mix of Silica sand No.5 and non-plastic silt. It was found that the erosion process varied depending on the initial density of the soil and higher density specimens showed relatively lower rates of erosion, degree of erosion, and compressive straining during erosion as compared with loose specimens. Effects on the mechanical behaviour​ of the soil were also dependent on the initial density of the specimen, with changes in the small strain stiffness, secant stiffness degradation, yield loci, small strain peak strength and medium strain strength in both drained and undrained conditions. In triaxial loading, force chains of coarse particles’ skeleton reinforced by fines developed in the suffusion process in the direction of major principal stress, then the stiffness at small strain increased. On the other hand, in torsional shear testing, the reinforced soil skeleton established by the erosion did not resist against shear loading. Increase in stiffness at small strain range was not observed.

内部侵蚀可能是导致水坝，堤防和堤坝等水力工程失灵的原因。渗流是一种内部侵蚀，其中细颗粒在渗流下通过粗颗粒之间的空隙迁移，而留下粗骨架。在这项研究中，使用5号硅砂和非塑料淤泥按间隙分级的土壤混合物，研究了在三轴压缩和扭转剪切作用下注水对土壤力学性能的影响。发现侵蚀过程随土壤的初始密度而变化，与松散试样相比，较高密度的试样在侵蚀过程中显示出相对较低的侵蚀速率，侵蚀程度和压缩应变。对土壤机械性能的影响还取决于样品的初始密度，在排水和不排水条件下，随着小应变刚度，割线刚度退化，屈服位点，小应变峰值强度和中等应变强度的变化而变化。在三轴加载中，在注浆过程中，细粉增强了粗颗粒骨架的力链，使其沿主主应力方向发展，然后小应变下的刚度增加。另一方面，在扭转剪切试验中，由侵蚀形成的加筋土壤骨架不能抵抗剪切载荷。在小应变范围内未观察到刚度的增加。在注浆过程中，细颗粒增强了粗颗粒骨架的主链，使之沿主主应力方向增大，小应变下的刚度增加。另一方面，在扭转剪切试验中，由侵蚀形成的加筋土壤骨架不能抵抗剪切载荷。在小应变范围内未观察到刚度的增加。在注浆过程中，细颗粒增强了粗颗粒骨架的主链，使之沿主主应力方向增大，小应变下的刚度增加。另一方面，在扭转剪切试验中，由侵蚀形成的加筋土壤骨架不能抵抗剪切载荷。在小应变范围内未观察到刚度的增加。