The Formation Mechanism Of Debris Flow On Slope In Three Gorges Reservoir Area

The phenomena of debris flow on slope for engineering spoil which is due to in the construction process of various projects, not pay attention to ecological protection and unreasonable storage location of slag heap and in certain hydrodynamic conditions, resulting in spoil heap on slope movement or slip, collapse. In the process of large-scale town relocation at the Three Gorges Reservoir area, almost all of the engineering site are based on excavation leveling, excavation depth from several meters to dozens meters, which is bound to have a large number of engineering spoil. With the deeply newtown construction of the Three Gorges Reservoir area, more and more events of debris flows on slope for engineering spoil were caused due to engineering spoil improper disposal.In the Three Gorges Reservoir area, the phenomena of debris flow on slope widespreads and has great potential harm.Thus it is urgently needed to systematic research debris flow on slope for engineering spoil which is different from the natural debris flow on slope.Because of this reason, in this study, choose Chongqing Region of the Three Gorges Reservoir as the research object,to has a preliminary exploration research to the formation mechanism of debris flows on slope for engineering spoil applicating to test method as the main means. The results of the main contents are as follows:(1)This paper based on the field observations and lots of hydrology, meteorology, geology and topography data of the Three Gorges Reservoir area had analyzed and studied the environmental conditions of the formation , it demonstrated that rainfall conditions was conducive to the formation of the debris flows on slope for engineering spoil. Investigating by source,it shows that the engineering spoil produced in the economic construction process of towns,roads,mines opening in Chongqing reservoir were much in amount,wide in distribution,poor in stability,which provide the rich material sources of debris flows on slope for engineering spoil.(2) Take the sample of engineering spoil in Chongqing Reservoir, carried out X-ray spectral analysis and indoor sensitivity test:the proportion of engineering spoil, saturation water content, the natural capacity heavy and the test of permeability coefficient, and shear test of engineering spoil under different saturation,which obtain the relationship test chart among c, water content,and saturation.(3)Through the method of principal component analysis, it was known that the formation of the debris flows on slope for engineering spoil was worked by the antecedent rainfall and short duration rainfall intensity. The antecedent rainfall is prerequisites and the short duration rainfall intensity is directly condition.(4)Derived surface runoff during rainfall, underground runoff, seepage force, hydrostatic pressure and force of raindrops splash slag heap of slope stability factor calculation and formulas,according to soil mechanics, hydraulics, fluid mechanics and the theory of limit equilibrium, etc. The spoil-type debris flow mechanism of the reservoir area was established,and established the mechanism of debris flow formation model of reservoir.(5)By conducting indoor modeling experiment on developing processes for debris flow on slope for engineering spoil, under less than 25o,the prophase rainfall 120mm and short diachronic rainfall intensity 16.7mm/10min.It reveals that the geomorphic mechanical properties of the formation and evolution of debris flow on slope for engineering spoil through the analysis of the change of moisture content , pore water pressure and surface displacement elevation with rainfall duration of engineering spoil on slope.