厚层基岩滑坡软弱夹层演化过程及控滑机理研究

发布时间：2018-05-19 21:33

本文选题：厚层基岩滑坡 + 软弱夹层　；参考：《长安大学》2016年博士论文

【摘要】：层状基岩斜坡是指岩体内分布有一组占绝对优势结构面的斜坡,优势结构面一般为层面、软弱夹层或者是节理面,它们是复杂岩体的典型特征之一。厚层状基岩斜坡在我国川滇、黔渝、鄂湘等西南山区广泛分布,该区域层状结构山体往往发育有数层岩性为泥岩、粘土岩或页岩的软弱夹层(带),与岩体内部岩溶带或节理面构成岩体与山体的分离面,经过长期蠕滑变形失稳,发生崩塌、滑坡等地质灾害,灾害往往规模巨大、危害性极高。本文以重庆武隆鸡尾山滑坡为例,对受软弱夹层控制的厚层基岩滑坡失稳机理开展了研究。在详细的现场地质调查基础上,查明了滑坡形成的地质环境背景,理清了滑坡的基本特征与变形历史,阐明了滑坡的失稳模式和成因机制。从导致滑坡蠕滑变形的关键因素——软弱夹层和岩溶带的强度衰减问题入手。结合现场地质调查成果和室内岩石分析试验,探讨了软弱夹层的沉积环境与物质基础、发育演化特征和岩层结构,提出了鸡尾山型滑带软弱夹层的演化模式与演化发展阶段:原生软岩→层间剪切带→滑带,从矿物学、力学和物理化学等方面解释了层状基岩软弱夹层的演化机制。开展了软弱夹层剪切流变力学试验,建立了适合软弱夹层各演化阶段的非线性损伤流变力学模型。采用有限差分软件FLAC3D模拟了岩溶发育带不同岩溶程度的剪切破坏特征。基于鸡尾山后部驱动块体驱动,前缘关键块体阻滑的滑动机制,推导并建立了受软弱夹层控制的厚层状基岩滑坡的三维极限平衡分析力学模型,计算了不同方案滑坡体的下滑推力与安全系数的变化趋势,从力学上揭示了受软弱夹层控制的层状基岩滑坡的失稳机理。并将三维极限平衡分析力学模型推广应用到变岩层倾角的条件下层状基岩滑坡的稳定性分析中,得到了变倾角条件下不同方案滑坡稳定性的影响规律。本文通过以上研究,取得了以下主要结论:(1)层状基岩滑坡的稳定性受地形地貌、地层组合、岩体结构、岩溶发育等方面的控制,具有后部驱动块体驱动,前缘关键块体阻滑的滑动机制。滑坡体的变形历史追溯久远,底部软弱夹层强度降低与侧边界岩溶发育带剪断构成了层状基岩滑坡蠕滑变形的关键因素。(2)分析了软弱夹层形成滑带的发育特征、矿物成分、微结构等方面的演化过程,提出了鸡尾山型滑带软弱夹层的演化模式,将其分为三个演化阶段:原生软岩→层间剪切带→滑带,并从力学、矿物学和物理化学等多学科角度揭示了鸡尾山型软弱夹层的演化机制。(3)开展了剪切流变试验,获取了软弱夹层各演化阶段的力学强度参数,并通过流变力学特性研究,解释了软弱夹层在演化中强度参数逐渐衰减的过程。引入损伤变量,建立了适合软弱夹层各演化阶段的非线性损伤流变力学模型。同时,采用有限差分软件FLAC3D模拟了不同岩溶发育程度溶蚀岩块的剪切破坏特性,定量评价了溶蚀岩体的强度衰减过程。(4)基于鸡尾山关键块体理论,分别讨论了边界强度条件的不同方案组合,推导并建立了受软弱夹层控制的层状基岩滑坡的三维极限平衡分析力学模型,计算了几种方案条件下滑坡体稳定性的三维变化趋势,并进行了对比分析。从力学上揭示了受软弱夹层控制的层状基岩滑坡的失稳机理。(5)将三维极限平衡分析力学模型推广应用到变岩层倾角条件下滑坡的稳定性评价中,讨论了滑坡处于临界状态时,底滑面与岩溶带抗剪强度参数组合的变化范围,并建立了不同倾角条件下关于边界强度参数的滑坡稳定性的三维临界曲面。
[Abstract]:The stratified bedrock slope is a slope in which the rock is distributed in a group of absolutely dominant structural surfaces. The dominant structural faces are generally stratified, weak intercalated or joint surface. They are one of the typical characteristics of complex rock masses. The thick layered bedrock slopes are widely distributed in Western Nanshan District, such as I, Qian Yu, Huxiang and other Western Nanshan District. The development of several layers of lithology is the weak interlayer of mudstone, clay rock or shale, and the karst zone or joint in the rock mass formed the separation surface of the rock mass and the mountain. After a long period of creep deformation, collapse, landslide and other geological disasters, the disaster is often large and dangerous. This paper takes the landslide of the chicken tail mountain in Wulong, Chongqing as an example, to be soft. On the basis of detailed field geological survey, the geological environment background of the landslide is found on the basis of detailed field geological survey. The basic characteristics and deformation history of the landslide are clarified, and the instability mode and the cause mechanism of the landslide are clarified. The key factor which causes the creep deformation of the landslide is the weak interlayer. Based on the results of field geological survey and laboratory rock analysis test, the sedimentary environment and material foundation of the weak intercalation, the characteristics of development and evolution and the structure of rock strata are discussed. The evolution mode and evolution stage of the soft interlayer of the chicken tail mountain type slide zone are put forward: the primary soft rock, the interlayer shear zone and the slide zone. From the aspects of mineralogy, mechanics and physics and chemistry, the evolution mechanism of the soft layer of layered bedrock is explained. The shear rheological mechanics test of soft intercalation is carried out, and a nonlinear damage rheological model suitable for the different evolution stages of the weak intercalation is established. The finite difference software FLAC3D is used to simulate the shearing of the karst development zone with different karst degrees. Based on the sliding mechanism of the driving block in the rear of the chicken tail mountain and the sliding mechanism of the key block in the front edge, a three-dimensional limit equilibrium analysis mechanical model of the thick layered bedrock landslides controlled by the weak intercalation is derived and established. The change trend of the sliding thrust and the safety factor of the different landslide bodies is calculated, and the mechanics of the landslide are revealed by the mechanics. The instability mechanism of layered bedrock landslides controlled by weak intercalation is applied to the stability analysis of layered bedrock landslides under the condition of the dip angle of variable rock stratum, and the influence law of the landslide stability under the condition of variable dip angle is obtained. The following main conclusions are obtained through the above study. (1) the stability of stratiform bedrock landslides is controlled by topography, formation, rock structure, and karst development. The landslide is driven by the rear driving block and the key block of the front edge is slipping. The deformation history of the landslide is traced back long, the strength of the weak intercalation at the bottom and the side boundary karst development zone cut down to form the layered bedrock. The key factors for the creep deformation of the landslide. (2) the evolution of the development characteristics, mineral composition and micro structure of the soft intercalation zone were analyzed. The evolution mode of the soft interlayer of the chicken tail mountain type slider was proposed, and it was divided into three stages of evolution: primary soft rock, interlayer shear zone and sliding zone, and from mechanics, mineralogical and physical chemistry. The evolution mechanism of the weak interlayer of the chicken tail mountain type was revealed in the multidisciplinary perspective. (3) the shear rheological test was carried out to obtain the mechanical strength parameters of the weak intercalation stages, and through the study of the rheological mechanics, the gradual decay process of the strength parameters in the evolution of the weak intercalation was explained. The damage variable was introduced and a suitable soft clamp was established. At the same time, the nonlinear damage rheological mechanics model of each evolution stage is modeled. The shear failure characteristics of different karst erosion rocks are simulated by the finite difference software FLAC3D, and the strength attenuation process of the dissolved rock mass is evaluated quantitatively. (4) based on the key block theory of the chicken tail mountain, the different combinations of the boundary strength conditions are discussed respectively. The three-dimensional limit equilibrium analysis mechanics model of layered bedrock landslides controlled by weak intercalation is derived and established, and the three-dimensional trend of the slope stability of several scheme conditions is calculated, and the comparative analysis is carried out. From the mechanics, the instability mechanism of the layered bedrock landslides controlled by the weak intercalation is revealed. (5) the three-dimensional limit equilibrium is balanced. The analytical mechanics model is popularized and applied to the stability evaluation of the landslide under the condition of the variable rock layer angle. The variation range of the combination of the shear strength parameters of the bottom sliding surface and the karst zone is discussed when the landslide is in the critical state, and the three-dimensional critical surface of the landslide stability under the condition of different inclination angles is established.
【学位授予单位】：长安大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P642.22

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