秦巴山区千枚岩边坡顺层破坏机理研究

发布时间：2018-07-04 23:37

本文选题：秦巴山区 + 千枚岩斜坡　；参考：《长安大学》2015年硕士论文

【摘要】：秦巴山区位于我国中西部地区,区域内地质条件复杂,地形起伏显著,断裂发育,岩体破碎风化严重,降水丰富,工程活动活跃,是我国地质灾害多发地区之一。陕南秦巴山区变质岩斜坡分布广泛,岩性以千枚岩、板岩、片岩等为主,其中千枚岩斜坡以其多节理、强度低、风化严重等特点为秦巴山区典型代表斜坡。在自然和人为因素影响下,千枚岩斜坡频频发生滑坡、崩塌等灾害,对当地人民生活造成重大安全隐患。因此,开展千枚岩斜坡变形破坏机制研究对秦巴山区千枚岩滑坡灾害防治具有重要意义。本论文以秦巴山区顺层千枚岩斜坡为研究目标,选取旬阳县尧柏水泥厂滑坡为典型研究对象,通过滑坡测绘与勘察确定其典型剖面、岩体结构、地质构造等工程地质条件和滑坡物质组成、变形破坏等特征。以尧柏水泥厂滑坡为原型开展室内物理模型试验,分别探究长期重力作用、不同层面组合、不同节理组合和坡脚开挖对千枚岩斜坡顺层破坏的作用机制,并对试验进行数值模拟,分析四种工况下斜坡的变形破坏特征、应力发展规律和破坏模式,以此建立坡体在整体式滑动破坏中的不稳定岩体长度的计算模型和千枚岩边坡稳定性与软弱面埋深的关系模型。模型试验中采用自行开发的非接触式位移监测系统,监测模型中所有可视岩块的位移数据,并及时记录边坡变形破坏的运动形态。最后,采用三维离散元软件3DEC模拟尧柏水泥厂滑坡的变形破坏,分析坡体在初始破坏阶段的变形、应力演化、应变累积特征以及滑动破坏过程中坡体的位移变化规律,揭示出滑坡以“滑移-拉裂”为主的顺层破坏机理,破坏过程表现出渐进破坏的特征。通过上述研究,本文取得以下成果:(1)尧柏水泥厂千枚岩斜坡滑动破坏受地形地貌、岩性组合、地质构造等自然因素和人类工程活动等外在因素影响。自然因素从本质上决定原始坡体的易滑性,坡脚开挖则作为诱发条件导致坡体的滑动破坏。坡脚开挖造成坡体中前部最大和最小主应力分别增大和减小,浅表层甚至出现“拉-压”应力组合,坡体在此应力组合下沿节理面压致拉裂;坡脚出现剪应力集中,剪应力集中条带逐渐发展为滑移带,最终发生“滑移-拉裂”渐进式破坏;(2)滑坡模型试验和三维数值模拟显示,层面强度、结构面组合以及坡脚开挖方式等影响千枚岩边坡变形破坏规律。软弱面加速坡体的滑动破坏,控制坡体的滑动面和破坏模式,使其具有整体滑动破坏的特征,坡体稳定系数随软弱面埋深增大而降低并最终保持最小稳定系数;结构面倾向与坡向的夹角影响边坡稳定性,夹角在20-30°时,坡体稳定性较高,不利结构面的倾向使坡体破坏具有“左旋性”特征;分级开挖坡脚后坡体滑动破坏具有“滞后性”,以“滑移-拉裂”整体式破坏为主;整体开挖后坡体滑动破坏则具有“迅速性”,以“滑移-拉裂”渐进式破坏为主;(3)采用极限平衡法,分别建立适用于整体式滑移破坏的不稳定岩体临界长度计算模型和千枚岩斜坡稳定系数与软弱面埋深的关系模型。前者表明不稳定岩体临界长度主要受层面强度、节理面抗拉强度、岩体密度、岩层倾角以及岩层厚度等控制;后者表明坡体稳定系数随软弱面埋深的增大而降低,最终降低为最小稳定系数Fs,min,Fs,min与软弱面摩擦角呈正相关,与岩层倾角呈负相关;(4)顺层千枚岩斜坡破坏模式包括“滑移-拉裂”渐进式破坏和“滑移-拉裂”整体式破坏。前者破坏机制为“蠕变-拉裂-滑移-拉裂-滑移”的累进破坏过程;后者破坏机制为“蠕变-拉裂-剪切-滑移”的整体破坏过程。
[Abstract]:Qinba mountain area is located in the central and western regions of China. The geological conditions are complex, the terrain is undulating, fracture development, rock mass breakage and weathering, heavy rainfall, and active engineering activities. The slope of metamorphic rock in Qinba mountain area of Southern Shaanxi is widely distributed, lithology is mainly phyllite, slate and schist. Under the influence of natural and man-made factors, the slope of the phyllite slopes frequently, such as landslides and collapses, caused by the natural and man-made factors, causing major safety hazards to the people of the local people. Therefore, the study of the mechanism of the phyllite slope deformation and destruction to the phyllite in Qinba Mountain Area is slippery. The prevention and control of slope disaster is of great significance. In this paper, taking the bedding phyllite slope in Qinba mountain area as the research target, the landslide of Yao Bai cement plant in Xunyang county is selected as the typical research object, and the typical section, rock mass structure, geological structure and other characteristics of the landslide material composition, deformation and damage, etc. are determined by landslide surveying and surveying. The physical model test of the landslide in the Bai cement factory is carried out as a prototype. The mechanism of the long-term gravity action, the combination of different layers, the combination of different joints and the slope foot excavation on the failure of the phyllite slope is investigated, and the numerical simulation is carried out to analyze the characteristics of the deformation and failure of the slope under the four conditions, the law of stress development and the failure mode. In order to establish the calculation model of the unstable rock length of the slope in the overall sliding failure and the relationship model of the stability of the phyllite slope and the buried depth of the soft surface. In the model test, the self developed non-contact displacement monitoring system is used to monitor the displacement data of all the visible rocks in the model and to record the deformation and failure of the slope in time. In the end, the deformation and failure of landslide in Yao Bai cement plant are simulated by the three-dimensional discrete element software 3DEC, and the deformation, stress evolution, strain accumulation and displacement of the slope during the initial failure stage are analyzed, and the failure mechanism of the landslide in the sliding failure process is revealed, and the failure mechanism of the landslide is mainly "slip and pull", and the failure of the landslide is revealed. The following results are obtained: (1) the sliding failure of the phyllite slope in the Yao Bai cement plant is influenced by the natural factors such as topography, lithology combination, geological structure and other natural factors such as the human engineering activities. The maximum and minimum main stress in the front part of the slope increases and decreases, and the shallow surface even appears the "pull pressure" stress combination, and the slope body is pressed to crack along the joint under this stress combination, the slope foot appears shear stress concentration, and the shear stress concentrating strip gradually develops into slip zone. Finally, "slip and pull" progressive failure occurred. (2) the landslide model test and three-dimensional numerical simulation show that the deformation and failure laws of the phyllite slope are affected by the strength of the plane, the combination of the structure surface and the way of the slope excavation. The sliding failure of the soft surface acceleration slope, the sliding surface and the failure mode of the slope are controlled, so that it has a whole sliding failure. Characteristic, the slope stability coefficient decreases with the burial depth of the soft surface and eventually maintains the minimum stability coefficient; the angle between the structure surface and the slope affects the slope stability. The slope body stability is higher when the angle is 20-30 degrees. The inclination of the unfavorable structure surface makes the slope failure have the "left rotation" characteristic, and the sliding failure tool of the rear slope body after the grade excavation slope is broken. There is "lag", which is mainly "slip and crack" failure. The sliding failure of the slope body after the whole excavation is "quick" and "slip and pull" progressive failure mainly. (3) the critical length calculation model of unstable rock mass suitable for holistic slip failure and the stability of phyllite slope are established by the limit equilibrium method. The former shows that the critical length of the unstable rock mass is mainly controlled by the strength of the layer, the tensile strength of the joint surface, the density of rock mass, the dip angle of the rock and the thickness of the rock layer, and the latter indicates that the slope stability coefficient decreases with the increase of the depth of the soft surface, and finally reduces to the minimum stability coefficient Fs, min, Fs, min and weakness. There is a positive correlation between the surface friction angle and the rock dip angle; (4) the failure mode of the CIS phyllite slope includes "slip and pull" progressive failure and "slip and pull". The former failure mechanism is the progressive failure process of "creep crack sliding crack sliding", and the latter failure mechanism is "creep splitting shear shear slip". The whole process of destruction.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P642.2

【引证文献】