Field testing of irrigation effects on the stability of a cliff edge in loess, North-west China

As it is not uncommon that irrigation has triggered landslides in the Chinese Loess Plateau, a full-scale field testing in a typical cracked plateau in Heifangtai, Gansu Province of China to simulate such phenomenon was conducted. In the study, piezometers were installed to measure the groundwater, and crackmeters as well as inclinometers were used to measure the slope movement. Water was pumped from the nearby source daily to simulate the irrigation process. There was a sharp increase of pore pressure in the undisturbed loess below the crack when the inclinometer registered considerable movement due to the inflow of water via the crack. Such increase in pore pressure also dissipated rapidly. Eventually, the irrigation water daylighted at the major cracks from the face of the plateau leading to local failures. The results show that cracks have significant effects on the flow of the irrigation water into the ground. The rapid rise in the local pore water pressure had reduced the stability of the slope.