碎石土滑坡的因素敏感性计算分析

Sensitivity analysis of influencing factors of debris landslide

通过资料搜集整理和分析、现场工程地质调查与勘探和室内外的物理力学试验,采用弹塑性接触有限元强度折减法、不平衡推力法和数理统计分析法,结合工程实例,分析了影响碎石土滑坡各因素的敏感性,结果表明,按因素敏感度从大到小排列,主要影响碎石土滑坡稳定性的因素依次为滑面岩土体内摩擦角、地形坡度、滑体饱水面积比和滑面岩土体的内聚力。地形坡度大、具有低内摩擦角滑面的碎石土滑坡的整体稳定性较差,而连续降雨、强降雨会抬高地下水位增大滑体饱水面积比,降低滑面带岩土体抗剪强度,增加下滑力,对碎石土滑坡的稳定性将产生最不利的影响。同时,在对碎石土滑坡进行加固处理时,必须优先考虑采取提高滑面等效内摩擦角、降低地形坡度结合降低地下水位措施,其次考虑采取提高滑面岩土体内聚力的措施。

Connected with the engineering concrete example, through the collection, arrangement and analysis of related data, the site investigation and exploration of engineering geology, indoor and outdoor physico-mechanical tests, adopting the analytic means of mathematic statistics, unbalanced-thrust method and non-separation contact elastoplastic FEM together, the influencing factor sensitivity of debris landslide has been analyzed and researched. The results show as follows. First, through the sensitivity analysis of main factors to influence on the stability of debris landslide, its main influenced factors are internal friction angle of sliding surface, topographic grade, saturation-area ratio of slope-mass and cohesion of sliding surface by descending order of their sensitivity coefficients. Second, the integral stability coefficient of debris landslide with large topographic grade and the slip surface of small internal friction angle is more inferior. But steady rain and intensive rainfall can raise groundwater level, augment saturation-area ratio of slope-mass, lower the rock and soil shear strength of slip-surface, and increase downward sliding force, which will bring about the most disadvantage influence on the stability of a concrete debris landslide. Meanwhile, on reinforcing and treating the debris landslide, the measure raising equivalent angle of slip-surface internal friction and lowering topographic grade connected with lowering groundwater level must be taken the prior step, and may be thought over taking the next measure to increase the soil and rock cohesion of slip surface.