Abstract:

Taking one of the typical aeolian-fluvial interaction dominated watersheds in the Ningxia-Inner Mongolia reach of the Upper Yellow River as the study area， while focusing on the gully desert mud flows characterized as a extreme pattern that the accumulation body blocks the channel， straight channel generalized model tests were carried out on the pore water pressure variation characteristics and the initiation processes of the accumulation body under the upstream runoff infiltration condition. Meanwhile， the fluid-solid coupling model based on the effective stress principle was adopted to simulate the catastrophic micro-mechanism from the perspective of the primary initiation stage of the mud flow disasters. The results indicated that the relationship between pore water pressure and time is a power function with an exponent of 0.5. Under the effects of fluid-solid coupling， the accumulation body experienced a complex nonlinear process of stress field → volume strain → porosity → pore water pressure → seepage field → plastic strain → yield failure. Our results can also provide a new method and approach for early warning and prevention of the gully desert mud flow disasters in terms of pore water pressure monitoring.

Key words: gully desert mud flow, aeolian-fluvial interaction, fluid-solid coupling, pore water pressure, initiation process