【作者】 唐军平；

【导师】 程谦恭；

【作者基本信息】 西南交通大学 ， 地质工程， 2008， 硕士

【摘要】 咪白代滑坡为云南省新平县境内一巨型古滑坡,距离老厂乡约6km,老厂乡竹园村咪白代、散红代和哥补村坐落其上。本文以咪白代滑坡为研究对象,在野外地质调查、收集及分析地质资料的基础上,详细阐述了咪白代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。经过岩样采集,借助室内试验和工程地质类比方法,获得了本滑坡体岩体的主要物理力学参数。通过对滑坡坡体原型得逆演分析,应用极限平衡理论分析了自然状态下斜坡的稳定性,并应用拟静力法以惯性力系简化地震作用计算分析了斜坡在地震作用下的稳定性。最后,论文借助FLAC^2D数值分析软件对斜坡的变形演化进行了模拟分析。研究认为,咪白代滑坡源区坡体岩体为白云石英变粒岩,含薄片状云母片岩软弱夹层。滑体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白云石英变粒岩,中间软弱夹层为白云片岩。岩层产状近水平,发育有一组与片理面正交的节理。在构造运动或卸荷作用下,沿该组陡倾节理极易发育成滑坡后缘拉裂缝,这种特殊的物质组成和结构面组合形式导致坡体上部沿该类结构面追踪形成贯通面,使坡体极易沿着拉裂缝和软弱夹层向下蠕滑。咪白代滑坡滑源区坡体属于软弱基座斜坡,在上述特殊的物质组成、岩体物理力学性质与结构面控制下,呈深部塑流-拉裂的地质力学模型特征渐进性变形。最后,在地震的作用下,坡体失稳,产生滑坡。论文在稳定性计算方面,首先采用极限平衡理论及拟静力法对斜坡的稳定性进行了计算分析,分析结果表明,在不考虑地震作用的自然状态下,斜坡稳定;当考虑地震作用时,斜坡失稳。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现象,沿软弱层形成剪切屈服区,位移量较小,斜坡稳定;而在地震触发作用下,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】 Mibaidai landslide is a huge ancient landslide in Xinping county of Yunnan province, about 6km away from Laochang town. Laochang town’s bamboo garden villages Mibaidai, Sanhongdai and Gebu village are located in it.This thesis, taking Mibaidai landslide as the research object, based on the site geological survey, geological materials collection, and analysis, illustrated in detail the engineering geological characteristics of Mibaidai landslide, and generalized geomechanics model of the landslide’s formation according to it; through rock sampling, lab tests and engineering geological analogy method, it gained the main physical and mechanical parameters of this landslide’s rock body; through the counter-succession analysis of the landslide body, it analyzed slope’s stability under natural condition by limit equilibrium theory; and it computed and analyzed the slope’s stability under earthquake action by pseudo-static method when using the inertial force system to simplify earthquake action. Finally the thesis made simulation analysis for the slope’s deformation evolution by FLAC^2D numerical analysis software.According to the research, it is thought that the rock body of Mibaidai slope’s origin zone is dolomite quartz leptynite, which has mica schist weak intercalation in the shape of thin flakes in it. The sliding body’s material composition has the three-layer structural characteristics of hard upper layer, soft middle layer and hard lower layer in macroscopic view, the overlying and underlying relatively hard layer is dolomite quartz leptynite, and the middle weak intercalation is dolomite schist. The rock body schistosity plane is nearly horizontal and has developed a set of joints outward to the slope, orthogonal with the schistosity plane. Under tectonic movement and unloading effect, it’s very easy to develop tension cracking on the top of the slope along the steep joints developed in rock body, this special material composition and structural plane combination form resulted in the through plane on the top of the slope along this structural plane, which made the slope easy to creep downward along the tension crack and dolomite schist weak intercalation. Mibaidai landslide sliding origin zone is weak base slope, its side slope with the geomechanics model characteristics of deep plastic flow-tension crack. The slope body developed by landslide took place progressive failure caused by the above special material composition, rock mass physical mechanical property as well as the control of structural plane under gravity, finally the slope lost stability and landslide happened under the earthquake action.In the aspects of stability computation, this thesis first adopted the limit equilibrium theory analysis and pseudo-static method to make computation and analysis for the slope’s stability. The computation result shows that when not considering the earthquake action, the slope is stable, while when considering the earthquake action, the slope loses stability.The result of numerical analysis shows that when the slope is under natural condition, the lower base of slope and the middle and lower place of the overlying rocks of weak formation appears shear stress concentration, formation of shear yield region along the weak intercalation as well as relatively small displacement and the slope is stable; while under the triggering action of earthquake, the slope body’s shear stress and displacement leaps, the slope’s trailing edge joint’s opening increases gradually, the yield region gradually expands through and the slope lost stability.更多还原