When groundwater flows through soil, it generates a seepage force that can detach and transport particles if it exceeds gravitational and interparticle resistance.

It refers to a process in which seepage flow induces continuous particle migration, progressively forming a connected erosion channel (a “pipe”) inside the soil.

Under seepage flow, fine particles are selectively transported through the pores of a coarse skeleton while the overall soil structure remains largely intact.

This process does not involve seepage erosion or particle detachment. Instead, groundwater alters the stress state of the soil skeleton, thereby reducing soil strength.

Boiling refers to the condition in which soil particles begin to lose contact and become suspended, resembling a fluidized state.

Heave refers to the upward displacement or bulging of the ground surface due to hydraulic uplift.

In this type of process, groundwater does not directly transport particles. Instead, it reduces soil strength, which subsequently enhances surface erosion driven by flowing water.