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Shallow landslides triggered by heavy rainfalls have caused casualties and economic losses to domestic infrastructures and industries worldwide. Rainfall mainly reduces the soil matric suction and the shear resistance, resulting in shallow landslides. Vegetation is an eco-friendly and cost-effective method for stabilizing slopes prone to shallow landslides. This research aims to investigate the hydrological and mechanical effects of vegetation on slope stability through a numerical study approach. Vegetated and bare slopes were subjected to a recorded climate condition and two rainfall scenarios of high intensity (HI) and low intensity (LI). Matric suction and factor of safety of vegetated and bare slopes subjected to rainfall were investigated. The matric suction of the vegetated slope at the surface was approximately four times greater than the bare slope after the HI scenario. However, the matric suction is about three times greater in the LI scenario. The results indicate that planting on slopes would reduce the vulnerability of bare slopes to the HI rainfall due to the higher matric suction and additional cohesion induced by the root system. These findings suggest that using vegetation in Rasht, Iran, where the climate data were collected, has considerable potential for stabilizing slopes.

Dynamic characteristics determine the mobility of debris flow and are also key to hazard risk assessment. However, the dynamic process of natural debris flow is very complex. Based on the systematic analysis of the field observation data of 93 debris-flow events at Jiangjia Ravine (Yunnan, China), this study attempts to investigate the dynamic mechanisms and sources of flow resistance of debris flow. The Jiangjia Ravine debris flows are almost completely liquefied, indicating that grain contact friction plays a negligible role. Flow regime analysis shows that the flow regimes of the Jiangjia Ravine debris flows varie from viscous to inertial. The fluid viscous effect and particle collisions may be the main sources of flow resistance.

This paper studied the rule of micro-hole in electrochemical jet machining (EJM) of TC4 alloy and established the mathematical model of machining process and predicted the machining profile. Considering the influence of machining gap and machining time, orthogonal experiment was designed. This paper established the mathematical model of the electrochemical jet machining process of TC4 alloy based on the response surface analysis (RSA) method. The results indicate that the electrochemical jet can improve the directivity of machining, reducing the machining gap can improve the machining efficiency, but the jet will cause secondary corrosion and abrupt change of current at the edge of inlet. The mathematical model based on response surface analysis is accurate after variance test. The experimental results show that the average error between the established prediction model of machining depth and the actual value is 2.32%, and the average error of the prediction model of inlet radius is 2.18%.