论文部分内容阅读
四川东部由紫红色砂泥岩构成的红层斜坡属于地质灾害多发易发区。斜坡内的软弱夹层(尤其是泥化夹层)容易遇水软化导致其力学强度降低,形成潜在滑动面。选取川东红层岩质滑坡原状滑带土进行室内饱水软化试验,揭示滑带土软化后微观结构和力学性质的变化规律。试验结果表明:滑带土饱水后内部结构变得疏松,颗粒间连接方式由面–面接触转化为面–边、边–边接触;黏聚力和内摩擦角随饱水浸泡时间呈指数衰减,直至浸泡10 d左右才逐渐趋于稳定。以试验获得的滑带土力学参数为基础,采用极限平衡法分析滑带土软化效应对研究区内斜坡稳定性的影响。计算结果表明,随着滑带土饱水时间的延长,斜坡稳定性系数不断降低,某些斜坡即使无后缘静水压力和底滑面扬压力的作用,斜坡也可能失稳破坏。由此认为,滑带土饱水软化后力学强度的大幅降低是导致红层地区某些岩质滑坡的重要因素。研究成果为认识四川红层地区滑坡机制和灾害防治提供了重要依据。
The red-bed slope composed of magenta sand-mudstone in the eastern part of Sichuan belongs to the prone areas where geological disasters occur frequently. Soft intercalations in the slopes (especially mud intercalations) tend to soften with water, leading to a decrease in their mechanical strength, creating a potential slip surface. The intact water softening test in the interior of the landslide with red beds in the east of Chuandong was selected to reveal the variation of the microstructure and mechanical properties of the sliding zone soils. The experimental results show that the internal structure of slippery soil becomes loose after saturated with water, and the interparticle contact mode changes from surface-surface contact to surface-edge and edge-edge contact. The cohesion and internal friction angle show an exponential Attenuation, until it was soaked about 10 d gradually stabilized. Based on the experimental data of the sliding zone soil mechanics, the influence of the softening effect of the sliding zone soil on the stability of the slope in the study area is analyzed by the limit equilibrium method. The calculated results show that the slope stability coefficient decreases with the prolongation of slippery soil saturation time, and the slope may be damaged by instability even if there is no effect of trailing edge hydrostatic pressure and bottom slip surface pressure on some slopes. Therefore, it is considered that the drastic reduction of mechanical strength of sliding zone soil after saturated with water is an important factor leading to some rock landslides in the red zone. The research results provide an important basis for understanding the landslide mechanism and disaster prevention and control in red beds in Sichuan Province.