【作者】 陈全明；

【导师】 任光明；

【作者基本信息】 成都理工大学 ， 地质工程， 2011， 硕士

【摘要】 根据层面与坡面的相互关系,层状岩质边坡可分为水平坡、横向坡、顺向坡、反向坡四种基本类型。其中顺向层状岩质边坡发生滑坡较为普遍。随着工程建设的开展,顺层岩质斜坡问题愈趋突出,顺层斜坡变形失稳是最常见的岩质边坡工程问题。通常认为顺层岩质斜坡的变形破坏以滑移-拉裂、滑移-弯曲模式为特征。但结合野外调查和文献搜索,在陡倾顺层岩质边坡还发现一类特殊的变形破坏方式,即倾倒变形。但根据以往的经验表明,倾倒变形一般只出现在近于直立或反倾层状斜坡当中。顺层斜坡倾倒变形破坏的特性与反倾坡截然不同,因此有必要加强对顺层岩质斜坡倾倒变形破坏机制的研究。本文以碧口近坝库区的两个典型滑坡为例,在阐明区内地质环境条件、滑坡的基本特征的基础上,研究了该类斜坡形成滑坡的基本特征要素和坡体结构特征;并应用数值模拟的手段对滑坡的成因机制以及各类控制因素对斜坡发生倾倒变形的影响规律进行了分析。通过上述研究,得出以下规律和结论:(1)在详细调查这两个滑坡的地质环境条件、滑坡特征的基础上,深入地研究了滑坡的坡体结构特征与变形破坏特征,并且详细分析、总结了顺层岩质斜坡发生倾倒变形破坏的基本特征和坡体结构。(2)在对白龙江碧口电站库区典型滑坡物质组成、结构特征以及成因机制等工程特性分析的基础上,恢复岸坡原始地貌,建立地质原型的三维模型。采用离散单元法对岸坡变形过程的各演化阶段进行了模拟。由此得出了陡倾顺层岩质斜坡的倾倒变形是在河谷演化、岸坡形成过程,岩层在平行坡面的最大主应力的作用下由坡体前缘开始向临空方向作悬臂梁弯曲,并逐渐发展到坡内,最终导致岩层在根部处折断,形成倾倒体。当坡体内折断带的剪应力超过其抗剪强度时,坡体将发生滑动形成滑坡。(3)应用离散元法计算了孟家干沟坍滑体在地震动荷载作用下边坡的位移变形。模拟结果的位移经过与地震后的实测位移对比,结果表明模拟位移跟实际位移比较接近。(4)在此基础上,利用三维离散元软件3DEC对顺层岩质斜坡的变形破坏规律进行数值模拟,通过逐一改变坡形、岩层倾角、坡度、坡高等条件来研究顺层斜坡倾倒变形的规律。分析结果可以得到:①较之凹形坡与平形坡,凸形坡更有利于斜坡的倾倒变形破坏。②一般来讲构成斜坡的岩层倾角在60°以上有利于倾倒变形的发生。③边坡的变形破坏程度随斜坡坡度的增大而增大。坡度高于30°是倾倒的优势坡度范围。④变形程度随着高度增加也跟着增加。在特定的地质环境条件下,当顺层斜坡的坡高>100m时,在层面倾角由45°变化到85°时,首先出现的是滑移-弯曲变形,逐渐发展到倾倒变形。数值模拟结果与实际斜坡倾倒变形情况相符。更多还原

【Abstract】 According to the angle’s relation of stratum and slope, the stratified rock slope can be divided into four parts: horizontal,transverse, reversal incline and bedding slope. Among these, the bedding slope is most likely to slide.Along with the development of the construction,the bedding rock slope problem is more extrude.The bedding rock slope’instabllity is the most familiar problem in rock slope engineering.Generally speaking,it is believed that slip-rupture and slip-bending are main characteristics of deformation and failure of bedding rock slope.However,based on the collection of systemic references and plenty of situ surveys,it is found that there is another particular form of deform ation and failure for steep bedding rock slope,namely,toppling deformation.On the basis of former experience,toppling deformation is one peculiar deformation mode belonging to reversal incline and vertical stratified slope .The bedding slopes are different from the counter-tilt slopes completely in mechanical properties. So it is necessary for us to do some research on the tilting deformation failure mechanism.Taking two typical landslides of Bikou reservoir close to the dam for an example,on the basis of clarifying geological environment conditions in the region and basic characteristics factors of the landslides, this paper summarizes basic characteristics and structural characteristics of the bedding slopes where the landslides come into being,and the formation mechanism of the landslides and the rule of the effect of the factors controlling deformation of slope is been carried out mainly by numerical simulation.Through this research,the following rules and conclusions drawn:(1)On the base of the detailed investigation of geological environment and basic characteristics factors of landslides,structural characteristics and deform ation and failure characteristics of landslides are deeply studied , and the basic characteristics and structural characteristics of the steep bedding rock slopes with toppling deformation are summarized and analyzed.(2)Based on the analysis of material composition,structure characteristic genetic mechanism,and other engineering geological characteristics of landslides of Bikou reservoir in Bailong River,the 3D numerica1 models of the geological prototype are established by estimating the ancient topographic and morphologic characteristics and reinstating the glided mass.Using the Distinct Element Method to simulate each evolved stage in the deformation process of the slopes,the results showed that in the process of valley evolution and slope formation and under the maximum principal stress of slope,which is parallel to the surface of slope,rock stratum bends from frontal edge gradually to the inner part of the slope as a cantilever beam.At last its root will be broken off,and a toppling body comes into being. On condition that the maximum shear stress exceed the shear strength in the cracked zone of the slope,it will slide and landslide happens.(3)The displacements of Meng Jiagangou landslide are calculated by distinct element method. Comparison between the simulation results and the field values of earthquake induced displacements shows that the displacements simulated by 3DEC are close to the field values.(4)Then,the deformation and failure rule of slope is researched by the way of numerical simulating deformation and destruction of bedding rock slope with three-dimensional rogram of 3DEC.By taking into account and changing geometric shape,height and angle of bedding slope and angle of interface separately,the influences on toppling deformation of bedding slopes are analyzed. Finally get the following conclusions:①Compared with planar sloped and concave slope, the toppling deformation of convex slope is easier to happen.②In general,it is easy for rock stratum to topple over when bedding dip is more than 60°.③It aggravates slope deformation with the increase of the slope angle. It is more likely for stratum to topple at the condition of the slope angle above 30°.④The deformation increases with height. When the slope is higher than 100m with particular geological environment,bedding dip increasing from 45°to 85°,slope failure mode will transit from sliding-bendin mode to toppling mode.The calculated results accord with the situation of toppling deformation in situ .更多还原