【作者】 李传宝；

【导师】 程谦恭；

【作者基本信息】 西南交通大学 ， 地质工程， 2007， 硕士

【摘要】 芭蕉树滑坡位于云南省新平县境内，发生于2002年8月14日上午8时30分。滑坡摧毁了芭蕉树村民小组，并造成8人死亡，3人失踪。本文以芭蕉树滑坡为研究对象，在野外现场地质调查和收集、分析地质资料的基础上，详细阐述了芭蕉树滑坡的工程地质特征，并由此概化出滑坡形成的地质力学模型；通过岩石力学试验和工程地质类比方法获得了滑坡主要工程地质岩组岩体的物理力学参数；应用极限平衡理论分析了地下水作用对斜坡稳定性的影响；应用能量守恒原理分别获得了滑体冲出剪出口时的启程速度和最大行程速度；并使用FLAC数值分析软件对斜坡变形演化及暴雨触发破坏阶段的应力、位移、塑性区发展特征进行了分析。研究认为，芭蕉树滑坡源区坡体岩体为黑云斜长片麻岩，云母片岩软弱夹层成薄片状夹于黑云斜长片麻岩中。岩体片理面陡倾坡外，且发育一组与片理面正交的垂直节理，节理走向与坡体倾向一致。物质组成在宏观上具有上硬中软下硬的三层式结构特征，上覆和下伏相对硬层为黑云斜长片麻岩，中间软弱夹层为白云母片岩。上覆岩体极易沿着白云母片岩软弱夹层向下蠕滑，导致坡体上部沿结构面追踪形成拉裂面。由于软弱层未临空，坡体前缘硬层对坡体变形起到阻碍作用，形成锁固段。因此芭蕉树滑坡的发育具有上段拉裂-中段滑移-下段锁固的三段式地质力学模型特征。滑坡发育的坡体由上述特殊的物质组成、岩体物理力学性质与结构面的控制，在重力的作用下，发生渐进性变形。最后，在暴雨入渗的作用下，斜坡后缘裂隙和软弱夹层内空隙水压力剧增，坡体失稳，触发了此次滑坡。极限平衡理论分析结果表明，在不考虑地下水作用下，斜坡稳定；而在考虑地下水作用下，斜坡失稳。采用能量守恒原理求得了滑体冲出剪出口时的速度和滑体行程的最大速度，分别为v_t=39.8m／s和v_max=44.5m／s。数值分析结果表明，斜坡在天然状态下坡脚和软弱层上覆岩体中下部出现剪应力集中，位移量较小，沿软弱夹层形成剪切屈服区，而锁固段岩体处于弹性阶段，斜坡稳定；而在暴雨触发作用下，坡体剪应力和位移剧增，斜坡后缘节理张开度逐渐增加，屈服区逐渐扩展贯通，斜坡失稳。更多还原

【Abstract】 Bajiaoshu landslide, which happened at 8:30, on 14^th of August, 2002, was located in Xinping, Yunnan Province. The lanslide destroyed the Village of Bajiaoshu, with 8 died and 3 lost.In this paper, Bajiaoshu landslide was studied. Based on in-situ geological survey and the analysis of geological data, engineering geology characteristics of landslide were expatiated particularly, and geo-mechanical model of landslide was proposed. Physical parameters of main rocks were obtained by rock tests and geological analogism. The impact on slope stability of under ground water was analysed by limit equilibrium method. And the starting velocity under water-cushion influence and maximal sliding velocity were gained by Energy Conservation Theory. Properties of stress, displacement and the extension of failed regions of the slope both under natural state and in rainstorm stage, were calculated by FLAC in this paper.The primal slope of Bajiaoshu landslide, which was consequent slpoe, was composed of biotite-plagioclase gneiss, while papery dolomite schist existed as a piece of interlayer. The composition of slope was provided with the three-ply property of up hard-mid soft-down hard as a pieceof hamburger. The up hard rock mass could easily slip creeply along the soft layer, which led crack occuring in the upside of slope. The deformation of slope was restrained by former hard rock mass, which acted as a locked segment, because the soft layer didn’t contact the air. So a geo-mechanical model of upside fracturing-mid sliding-under lucking-up was introduced to Bajiaoshu landslide in this paper. The landslide was controlled not only by special composition of material, but also mechanical characteristics and interfaces of rock mass. Under the action of gravity, the slope deteriorated gradually. Rainstorm generated high pore water pressure in back-crack and soft layer, which triggered the landslide.The results of limit equilibrium method showed that the slope was stable without consideration of the action of under ground water, but the slope failed while taking the influence of under ground water into account. The velocity at the time of sliding mass shearing out and the maximal velocity were obtained by Energy Conservation Theory. They were 39.8 m/s and 44.5 m/s, respectively. The results of numerical simulation showed that slope was stable under natural state, but in rainstorm stage, yielded regions in slope extended because of quick increasement of shear stress and displacement of slope. Once yielded regions ran through, the solpe failed.更多还原