There is thus an urgent need in this region to conduct a regional-scale debris flow susceptibility assessment to determine the spatial likelihood of a debris flow occurrence and guarantee the safety of people and property, in addition to the smooth operation of the Sichuan-Tibet transport corridor. It is also possible to consider a special type of surcharge - the water above the terrain.The eastern margin of the Qinghai-Tibet Plateau is an extreme topography transition zone, and characterized by significant vegetation zonation, in addition to geographic features (such as enormous topographic relief and active tectonics) that control the occurrence of debris flows, which are rapid, surging flows of water-charged clastic sediments moving along a steep channel and are one of the most dangerous mountain hazards in this region. The analysis then proceeds with the resultant of surface load p having the value: Scheme of spreading the concentrated load on the slip surface Providing the surcharge, essentially acting over the area b *l, is introduced as a concentrated force it is transformed before running the analysis into a surface load spread up to a depth of slip surface along the slope 2:1 as displayed in the figure.

The surcharge is always considered in the analysis with respect to one running meter. The components that do not act in the direction of weight are assumed in equations of equilibrium written for a given block as weightless thus neither contributes to inertia effects of the earthquake nor position of block centroid. The material surcharge component also influences the position of block centroid. It means that if the earthquake effects are included this component is also multiplied by the factor of horizontal acceleration or vertical earthquake. Since it is usually assumed that the surcharge is caused by the weight of objects found on the slope body, the vertical component of surcharge having the direction of weight (material component) is added to the weight of blocks. The surcharge can be introduced either as a concentrated force or distributed load acting either on the ground surface or inside the soil body. The slope stability analysis takes into account even the surcharge caused by neighboring structures.

Slope stability surcharge top