Study on the formative processes of a weathering profile of granite and the prediction of its landslides induced by rainstorms

对地下水位下水的通量、电导率和化学成分的连续监测，结合土壤水的孔压测量，阐明了雨水通过分解的花岗岩的过滤行为。暴雨首先通过裂缝等快速途径到达地下水位，在降雨事件中暂时降低了地下水的电导率。然后，湿润锋下降，通过传播包气带中的气压，推动毛细管边缘的水，逐渐增加地下水的电导率。毛细管边缘水富含分解花岗岩斜长石补给的钙，石英含量受方石英的沉淀控制。在毛细管水向下推后，雨水本身到达地下水位，降低了水的电导率。土壤水中的阳离子浓度受离子交换的控制。对包气带多深度土壤水孔压的测量表明，湿润锋以1m/(30h)的速度下降。地表松动土层在干湿迭代过程中发生蠕动，即使孔压仍为负值也会发生。

Continuous monitoring of the flux, the electrical conductivity, and the chemistry of water from just beneath the groundwater table clarified the filtration behavior of rainwater through decomposed granite in combination with the pore pressure measurements of soil water Heavy rainfall first reaches the groundwater table through express ways like cracks, temporarily reducing the electrical conductivity of the groundwater at a rainfall event. Then, a wetting front descends and pushes the water in the capillary fringe by propagating the air pressure in the vadoze zone, gradually increasing the electric conductivity of the groundwater. The water in the capillary fringe is rich in Ca supplied from plagioclase of the decomposed granite and its silica concentration is controlled by the precipitation of cristobalite. After pushing down of the capillary water, rainwater itself reaches to the groundwater table, decreasing the electrical conductivity of the water. Cation concentrations in the soil water are controlled by ion exchange. The measurement of pore pressure of soil water in multiple depths in the vadoze zone, indicated that the wetting front descends at a rate of 1 m/(30 h). Surface loosened soil layer creeps by the iteration of drying and wetting ; it occurred even pore pressure is still negative.