| Landslide is the most common form of geological hazards. Study on the correlation between aspect and slope stability has important guiding significance and practicability.In order to study the different aspect to the slope stability influence, the paper the first study microclimate characteristics of the different aspect from the following factor: solar radiation,temperature,evaporation,moisture, and to provide the theory basis for the correlation between aspect and slope stability.The aspect is an important terrain feature,which has the remarkable influence to local climate.The microclimate differences mainly manifest in the different solar radiation,temperature,evaporation and moisture aspects. These have profound influence to vegetation, soil and hydrology.Vegetation and climate are not a simple one-way relationship-driven, but are driven by their mutual relations feed. Because vegetation is different in different aspect, making the exchange of heat and moisture content has the significantly spatio-temporal change, thus causing the calorific capacity and the moisture content redistributes in the forest, causing the temperature, humidity have the change in the forest, and cause light,precipitation to redistribute.The research indicates that the sunny slope has south the local climate characteristic, but the shady slope has north the local climate characteristic.The microclimate differences display directly in the total degree of vegetation cover and the richness. The research shows that degree of vegetation cover and richness in shady slope is bigger than in sunny slope, and the shady slope is mostly forest, but the sunny slope is most of shrubs and annual herbs. The shady slope can reduce the infiltration quantity of the soil(three interceptions) through the complementarity effect of the arbor,shrub and herb, and can cause the shallow layer and in-depth root system obtains mutually the supplement in the soil body spatial distribution. Because of the shady and sunny slope differences of hydrothermal conditions, root system is presented to the slope aspect distribution characteristic. In the shady, the root density, the root surface area, the root system length are bigger than in the sunny.The shady stronger root system through the anchor, the reinforcement and the diagonal coupling hysteresis effect to increases the shearing strength of rock and soil, and suppresse the formation of cracks and the weathering denudation. Because of the monsoon climate, the precipitation in many parts has the obvious the facing slope characteristic, generally speaking, the sunny precipitation in the identical high is bigger than the shady side, and the good vegetation in the shady delay the water content extreme value arrival time the unsaturated area, thus causes the sunny slope to be most instable, simultaneously, relatively high temperature is also disadvantageous to the slope stability in the sunny slope.On the one hand, it reduces the moist peak to arrive at the time which the peak value needed; On the other hand, it reduces soil matric suction. Rainfall,rainfall intensity and daily range of temperature are big, and the temperature is high, as well as the rain hot same season combined action promote the soil body crack formation (frequently wetting/drying cycle) and accelerate the rock mass physical weathering and the chemical weathering. Ground water table fluctuant belt is the most intense region of CWRI, and the diurnalvariation of surface temperature is the primary factor which affects the diurnalvariation of ground water table, so the sunny slope becomes the most intense region of CWRI. Whether the formation of clay minerals or the evolution of cracks will reduce c andφto promote failure of slopes. Vegetation prevent soil erosion by intercepting rainfall,regulating runoff,the soil of consolidation and improved soil properties, but because light and heat conditions are so good that human activity is frequent in the sunny slope, this affect the vegetation cover, accordingly, accelerating s soil erosion, so as to be gradually evolved into landslide and debris flow. Numerous ravines are steeper and shorter in the sunny, which create the advantage for landslide. For rock slope, rock corrosion will also cause failure of slopes.Therefore, the influence of the aspect to the slope stability is notable, and further study show that, in general, sunny slope more easily induce landslide hazard. |
