反倾层状岩质斜坡倾倒变形特征及演化机理研究

发布时间：2018-06-10 06:38

本文选题：反倾边坡 + 倾倒变形　；参考：《中国地质大学》2015年博士论文

【摘要】：反倾边坡是指岩层走向与坡面走向近一致、岩层倾向与坡面倾向相反的一类边坡,般认为此类边坡稳定性较好,不易发生失稳,因此对其变形特征及稳定性研究成果较少,然而随着人类工程活动的日益频繁及范围扩大,此类边坡的安全稳定性问题开始广泛存在于矿山、水利水电、公路与铁路边坡等方面。在工程实践中,由于对此类边坡的变形特征、演化机制认识不足,往往不能正确判别其变形发展趋势,进而对其稳定性做出错误的判断。基于此,系统地开展反倾边坡变形破坏特征与演化规律研究,揭示其演化机制、机理,将有助于推进反倾边坡防灾减灾理论研究,具有较大的工程应用价值。对反倾边坡的研究首先要认清其变形特征,倾倒变形特征包括地表变形与深部变形两部分,地表变形特征受深部变形控制,深部变形特征通过地表变形得以表征。地表变形受空间位置、地质环境条件差异而在空间上呈现不同变形破坏特征,深部变形特征主要包括倾倒变形深度及变形深度范围内岩层倾角变化规律两部分,因此系统综合分析地表变形与深部变形才能正确揭示倾倒变形特征。目前对反倾边坡变形演化特征的研究内容较少,以往研究成果主要基于单个工程实例进行简单的某一阶段变形特征描述分析,没有将其视为一个动态演化系统。对反倾边坡而言,倾倒变形随时间呈现不同变化特征,不同倾倒变形演化阶段对应不同变形特征,因此需要将倾倒变形视为动态演化过程,某一阶段变形特征不能反映其整体变形发展状况。通过多种特征值演化信息获取综合分析而划分倾倒变形演化阶段,并建立各演化阶段与变形特征的对应关系,才能对其变形发展趋势做出正确预测。论文针对反倾边坡,以工程地质学、岩石力学为指导,结合地质调查、室内外试验、三维激光扫描、ArcGIS、数值模拟等技术方法,主要进行了如下四方面的研究工作：一、倾倒变形影响因子敏感性及易倾倒几何模型研究(1)分别选取最大水平位移、变形面积、总位移三种评价指标,对比分析了基于三种指标所得倾倒变形影响因子敏感性计算结果差异,并得出基于总位移评价指标的分析结果能弥补另外两种评价指标的不足,且结果最符合实际；(2)倾倒变形敏感性计算结果表明一级影响因子中几何特征因素对倾倒变形影响最大,二级影响因子中坡角、岩层厚度、密度、泊松比为高敏感因子；岩层倾角、岩体内摩擦角、层理内摩擦角为次敏感因子；弹性模量、岩体粘聚力、抗拉强度、层理刚度比、层理粘聚力为低敏感因子；(3)几何特征因子作用下响应规律分析结果表明,倾倒变形随坡度、岩层倾角增加而增加,随岩层厚度增加,倾倒变形总位移先增大后减小,并在0.2m处变形最大；(4)利用支持向量机建立了倾倒变形总位移预测模型,得出反倾边坡易倾倒几何模型为以坡度80°、岩层倾角80°、岩层厚度0.19m为圆心的四分之一椭球体,椭球长赤道半径长31°(岩层倾角轴向)、短赤道半径长21°(坡度轴向)、极半径0.075m(岩层厚度轴向),该椭球体长赤道半径：短赤道半径：极半径为2.48：1.68：1。二、倾倒变形破坏与时空演化特征分析(1)硝洞槽-郑家大沟岸坡实质为一弯曲倾倒变形体岸坡,依据地表变形空间分布特征,将岸坡地表变形共分为七个变形区,岸坡地表变形明显区主要分布在岸坡前部与后部,宏观表现为地表拉裂缝、崩坡积体滑移以及岩层弯曲折断；(2)物探、波速、平硐、探井等勘测分析结果表明倾倒变形影响深度为50m-110m,岸坡前部倾倒变形深度较浅、后部倾倒变形深部较深；(3)岸坡前部三维激光扫描与岸坡后部钻孔成像解译分析结果表明,岸坡前部岩层倾角变化不明显,岸坡岩体以剪切变形为主；岸坡后部岩层倾角随深度整体逐渐变陡,其中0-40m深度内岩层倾角以20°左右缓倾角为主,变化平缓,40m-85m深度内岩层倾角逐渐变陡并趋于正常,倾倒变形主要发生在40-85m深度范围内；(4)地表位移监测结果表明岸坡前部以水平变形为主,岸坡后部以垂直变形为主；深部位移监测结果表明岸坡900m高程以上呈倾倒变形破坏模式,其变形速率较慢、变形强度较弱,岸坡900m高程以下区域呈剪切破坏模式,其变形速率较快、变形强度较强；(5)岸坡倾倒变形演化周期为12个月,前四个月岸坡中部变形优势明显,并从右侧向左侧扩展呈带状,后八个月岸坡中部变形优势逐渐减弱,并从左侧向右侧消退呈点状,岸坡中部条带区域变形控制着整个岸坡变形演化规律,岸坡整体变形滞后于岸坡中部变形,中部条带状变形区位移的增加会诱发后期岸坡整体位移的增加,推断该带状区为倾倒变形锁骨段；(6)岸坡水平强变形最大面积区为中等坡度、低高程、北坡向区,占该区总面积的79.24%,岸坡垂直强变形最大面积区为低坡度、高高程、西北坡向区,占该区总面积的87.9%,岸坡倾倒变形整体以水平变形为主、垂直变形为辅。三、倾倒变形稳定性及演化机制研究(1)单剪试验不需事先假定剪切破坏面,所需剪应力小、剪应变大,对试样剪切破坏更彻底,试样破坏裂纹沿对角线呈45°线性分布,试样裂纹贯加载侧对角线,直剪试验裂纹近似呈直线贯通指定剪切破坏面,并发育近45°絮状次级裂纹,数值试验模拟结果表明单剪、直剪试验粘聚力之比为1.0：1.66,摩擦角度之比为1.0：1.08,力学参数差异主要表现在粘聚力上,单剪、直剪试验差异原因主要为二者试验过程中伺服器做功所转换的应变能、摩擦能比值差异显著；(2) Sarma法、WGB法、刚体极限平衡法三种稳定性系数计算方法所得岸坡稳定性变化趋势一致,WGB法由于考虑了滑动面的连通率与条块侧面剪应力而使稳定性系数计算结果偏高；刚体极限平衡法由于未考虑滑面连通率、条块侧面剪应力,因此其稳定性系数计算结果偏低；Srama法考虑了条块侧面剪应力,但未考虑滑面连通率而使稳定性系数计算结果居中；层状反倾岩质边坡变形受岩体结构面控制,岩体沿层面发生剪切变形,因此考虑条块侧面剪应力的WGB法和Srama法较刚体极限平衡法更适合反倾边坡；此外,WGB法和Sarma法均按实际岩层面划分条块,比铅直划分条块的刚体极限平衡法更能真实反映层状反倾岩质边坡的实际破坏情况；(3)库水作用前,岸坡700m高程以下为稳定区,岸坡岩体受上部倾倒变形下滑力作用而发生剪切变形并提供抗滑力,岸坡700-900m高程区域为较稳定区,为岸坡滑移、倾倒两种破坏混合区,岩层条块存在两种不同破坏模式,岸坡900m高程以上为基本稳定区,岩体发生倾倒变形提供下滑力；库水作用后,岸坡700m高程以下区域由于受库水作用,岩体弱化、强度降低而发生局部剪切变形破坏,由稳定区变为不稳定区,坡表变形以水平滑移变形为主；岸坡700-900m高程区域受下部滑移变形牵引及上部倾倒变形推压共同作用,由较稳定区变为欠稳定区；岸坡900m高程以上区域受库水影响较小,但因受岸坡中前部变形牵引而稳定性发生微弱变化,因此仍为基本稳定区,变形以垂直向倾倒变形为主；(4)岸坡倾倒变形、剪切变形分界面高程随层理力学参数成正比,层理力学参数越好,变形分界面高程越高,岸坡倾倒变形区越小,分界面高程受层理内摩擦角影响大于内聚力；当内聚力小于50kPa,且内摩擦角小于30°时,岸坡大部分区域会发生倾倒变形,剪切变形区仅分布于530m-546m高程段；当内摩擦角大于35°时,岸坡大部分区域以剪切变形为主,倾倒变形仅分布于1000m高程以上区域；(5)岸坡前期变形方式主要以倾倒变形条块数增加为主,岸坡倾倒偏转角度较小,偏转范围在8°以内；岸坡后续倾倒变形将表现为倾倒变形条块、倾倒变形角度同步陡增,在无外界因素影响下,岸坡将向倾倒条块数140块、倾倒角度30°附近区域演化；(6)库水作用后岸坡稳定性下降明显,新演化路径较原演化路径向倾倒条块坐标轴轻微偏移,库水作用对岸坡倾倒演化路径无明显影响,只是通过降低坡脚岩土体力学参数,使得岸坡前部抗剪强度降低,进而降低岸坡整体稳定性系数。四、倾倒变形特征值及其岸坡演化机理研究(1)在岸坡岩块微观参数校核的基础上,综合Hoek-Brown准则与数值试验确定了岸坡岩体力学强度参数；采用PFC软件模拟了岸坡倾倒变形演化过程,获取了岸坡倾倒变形过程中应力场、位移场、能量场多种特征值演化特征,岸坡前部在水平应力作用下发生剪切变形,岸坡中后部在垂直应力作用下发生倾倒变形；(2)应力场演化特征分析结果表明,岸坡在坡脚沟谷处呈高应力状态,岸坡浅层应力场以垂直应力为主,水平应力、垂直应力、剪应力沿深度整体上逐渐增加,演化过程中不同区域、不同演化时期应力场差异显著；(3)位移场演化特征分析结果表明,地表以水平变形为主,水平位移在高程900-1050m区段位移数值及增速最大,并以此为中心向坡脚、坡顶方向逐渐递减,坡顶水平位移值大于坡脚,地表垂直位移随岸坡空间分布规律与水平位移相似,岸坡前部由于剪切变形而隆起；岸坡中部深部位移随深度递增,呈典型倾倒变形特征；(4)能量场演化特征分析结果表明,倾倒变形演化过程中应变能最大、摩擦能其次、动能最小,各能量均随时步逐渐增加,能量陡升区间位于10万-30万时步；依据能量场演化特征曲线,将岸坡倾倒变形演化过程划分为剪切变形阶段、主倾倒折断面贯通阶段、次级倾倒折断面发育阶段等三阶段；(5)剪切变形阶段岸坡坡脚深部水平应力陡增,且越靠近坡脚谷底,水平应力值越大,高水平应力状态造成岸坡剪切裂纹从坡脚谷底处向坡体深部逐渐扩展贯通形成剪切折断面；受岸坡前部水平变形牵引,岸坡中部在自重作用下垂直应力增大并造成岩层倾角偏转沿深部发生倾倒折断,倾倒折断面沿岸坡中部向坡顶延伸并贯通形成主折断面；次折断面发育阶段,岸坡体变形主要受控于垂直应力,其中岸坡中部垂直应力波动大、前部次之、后部垂直应力变化平稳,岸坡前部次级折断面近似平行主折断面呈离散状分布于岸坡体剪切变形区,岩层倾角无偏转；岸坡中部次级折断面与主折断面呈弧形向坡外发育,且愈靠近坡面次级折断面倾角愈陡、岩层倾角愈平缓；岸坡后部次级折断面发育规模小,且与主折断面近似平行,岩层倾角偏转较小。本文研究的创新点主要有：(1)对比基于最大水平位移、变形面积、总位移三种评价指标下倾倒变形影响因子敏感性分析结果差异,综合确定倾倒变形影响因子敏感性大小,并通过对高敏感因子作用下倾倒变形响应规律研究得出倾倒变形易倾倒几何模型；(2)基于三维激光扫描、钻孔摄像等多种测量技术综合分析了倾倒变形空间变化特征,并利用ArcGIS分析了倾倒变形时空演化特征,确定了倾倒变形剪切变形区与倾倒变形区分布范围；(3)综合位移场、应力场、能量场演化特征进行了倾倒变形演化阶段划分,并分析了倾倒变形演化机理。
[Abstract]:The anti dip slope refers to a kind of rock slope which is close to the slope direction and the rock strata tend to be opposite to the slope. It is considered that this kind of slope is more stable and not prone to instability. Therefore, the research results of its deformation characteristics and stability are less. However, with the increasing frequency and scope of human engineering activities, the safety of this kind of slope is safe. Stability problems begin to exist widely in mines, water conservancy and hydropower, highway and railway slope. In engineering practice, because of the lack of understanding of the deformation characteristics and evolution mechanism of this kind of slope, it often can not correctly distinguish its deformation development trend, and then make a wrong judgment on its stability. Based on this, the reverse slope change is systematically carried out. The study of the characteristics and evolution laws of the shape failure and the mechanism of its evolution will help to advance the theoretical study of the anti dip slope prevention and reduction theory. It is of great engineering application value. The study of the reverse slope should first recognize its deformation characteristics, and the characteristics of the toppling deformation include two parts of the surface deformation and the deep deformation, and the surface deformation characteristics are deeply affected by the depth. The deformation characteristics of deep deformation are characterized by surface deformation. The surface deformation is affected by the spatial position, the geological environment is different, and the deformation and failure characteristics are presented in the space. The deep deformation features mainly include the two parts of the dip angle change law in the range of the toppling deformation depth and the depth of the deformation, so the system analyses the surface change synthetically. The shape and deep deformation can correctly reveal the characteristics of the toppling deformation. At present, the research content of the deformation and evolution characteristics of the reverse slope is less. The previous research results are mainly based on a single engineering example to describe the deformation characteristics of a simple stage, and do not consider it as a dynamic modeling system. The evolvement stage of different toppling deformation corresponds to different deformation characteristics. Therefore, the toppling deformation should be considered as a dynamic evolution process, and the deformation characteristics of one stage can not reflect the development of its whole deformation. The corresponding relationship between the phase and the deformation characteristics can be used to predict the development trend of the deformation. In this paper, the research work on the reverse slope, with the guidance of engineering geology and rock mechanics, combined with geological survey, indoor and outdoor tests, three-dimensional laser scanning, ArcGIS, numerical simulation and other technical methods, mainly carried out the following four aspects of research work: 1. The sensitivity of the influence factor of the inverted deformation and the study of the easy dumping geometry model (1) select the three evaluation indexes of the maximum horizontal displacement, the deformation area and the total displacement respectively, and compare and analyze the difference of the sensitivity calculation results of the influence factors of the dumping deformation based on the three indexes, and get the other two kinds of analysis results based on the total displacement evaluation index. The evaluation index is not enough, and the results are most consistent with the actual results. (2) the results of the deformation sensitivity calculation show that the geometric characteristics of the first order influence factor have the greatest influence on the toppling deformation. The slope angle, the thickness of the rock layer, the density, the Poisson's ratio are Gao Mingan factor, the dip angle of the rock layer, the friction angle of the rock mass and the internal friction angle of the bedding are sub sensitive. Factors such as modulus of elasticity, cohesive force of rock mass, tensile strength, bedding stiffness ratio, and cohesive force are low sensitive factors. (3) analysis of response laws under the action of geometric characteristics indicates that the toppling deformation increases with the slope and rock dip angle, and the total displacement of toppling deformation increases first and then decreases with the increase of the thickness of the rock layer, and is most deformed at 0.2m. (4) (4) the prediction model of the total displacement of dump deformation is established by support vector machine, and the easy toppling geometry model of the reverse slope is that the slope is 80 degrees, the dip angle of the rock layer is 80 degrees, the thickness of the rock layer is 1/4 ellipsoid of the center, the long equator radius of the ellipsoid is 31 degrees (the axis of the rock layer), the radius of the short equator is 21 degrees (the slope axis), and the polar radius is 0.075m ( The long equatorial radius of the rock layer: the long equatorial radius of the ellipsoid: the radius of the short equator: the polar radius is 2.48:1.68:1. two, the collapse deformation and the temporal and spatial evolution characteristics analysis (1) the nitre trough - Zhengjia ditu bank slope is essentially a curved slope deformed bank slope. According to the spatial distribution characteristics of the surface deformation, the surface deformation of the bank slope is divided into seven deformation zones. The obvious area of the surface deformation in the bank slope is mainly distributed in the front and back of the bank slope, and the macroscopic expression is the surface tensile crack, the slide of the landslide and the bending and fracture of the rock layer. (2) the results of geophysical prospecting, wave velocity, adit and exploration well show that the influence depth of the toppling deformation is 50m-110m, the depth of the dumping deformation in the front of the bank slope is shallow, and the deep toppling deformation in the rear is more than that of the slope. (3) the analysis of the three-dimensional laser scanning in front of the bank slope and the interpretation of the borehole imaging in the back of the bank slope shows that the rock slope angle in the front of the bank slope is not obvious, and the rock slope in the bank slope is mainly shear deformation, and the slope angle of the bank slope is gradually steepening with the depth, and the dip angle of the rock layer in the 0-40m depth is mainly about 20 degrees, the change is gentle, and the change is gentle. The dip angle of the rock layer gradually steepen and tends to normal in the depth of M, and the toppling deformation mainly occurs in the 40-85m depth range. (4) the surface displacement monitoring results show that the front part of the bank slope is mainly horizontal deformation, and the back of the bank slope is mainly vertical deformation, and the deep displacement monitoring results show that the slope 900m above the slope is a toppling deformation failure mode and its deformation rate. More slowly, the deformation strength is weak, the region below 900m elevation is shear failure mode, its deformation rate is faster, and the deformation strength is stronger. (5) the evolution period of bank slope collapse deformation is 12 months, the deformation advantage of the bank slope in the first four months is obvious, and it extends from the right to the left, and the deformation advantage of the bank slope is weakened gradually in the later eight months. The displacement of the left side to the right is a point shape. The deformation of the strip zone in the middle of the bank slope controls the deformation and evolution law of the whole bank slope, the whole deformation of the bank slope lag behind the deformation of the bank slope, and the increase of the displacement of the belt deformation zone in the central strip will induce the increase of the overall displacement of the bank slope in the later period, and deduce that the strip area is the clavicle section of the dumping deformation; (6) the horizontal deformation of the bank slope is strong. The maximum area is medium slope, low elevation and north slope area, which accounts for 79.24% of the total area of the area. The maximum area of vertical strong deformation is low gradient, high elevation, and northwest slope area, accounting for 87.9% of the total area of the area. The slope deformation is mainly horizontal deformation and vertical deformation is supplemented. Three, the stability and evolution mechanism of dumping deformation (1) The shear stress is small, the shear strain is large, the shear strain is larger, the shear failure is more thorough, the fracture crack is 45 degrees along the diagonal line, the specimen crack intersecting the diagonal line at the loading side, and the straight shear crack is approximately straight through the specified shear failure surface, and the 45 degree secondary crack is developed by the numerical test. The test results show that the ratio of cohesive force to single shear test is 1.0:1.66, the ratio of friction angle is 1.0:1.08, and the difference of mechanical parameters is mainly in cohesive force. The difference of single shear and direct shear test is mainly due to the strain energy converted by the server in the two experiments, and the difference of the ratio of friction energy is significant; (2) Sarma method, WGB method, rigid The stability variation trend of the bank slope is consistent with the three stability coefficient calculation methods of the body limit equilibrium method. The WGB method makes the calculation result of the stability coefficient higher because of the connection rate of the sliding surface and the lateral shear stress of the strip, and the stability coefficient of the rigid body limit equilibrium method is due to the failure of the slip surface connectivity and the side shear stress. The calculation results are low; the Srama method considers the shear stress of the strip side, but does not consider the connection rate of the sliding surface, which makes the calculation result of the stability coefficient in the middle. The deformation of the layered anti dip rock slope is controlled by the structure surface of the rock mass and the rock mass is shear deformation along the plane, so the WGB method and the Srama method considering the lateral shear stress of the strip are more than the rigid body limit equilibrium method. It is suitable for reverse slope slope; in addition, the WGB method and the Sarma method are all divided according to the actual rock layer, and the rigid body limit equilibrium method is more true to reflect the actual failure situation of the layered reverse rock slope. (3) before the reservoir water action, the slope of the bank slope is below the 700m elevation as the stable area, the slope rock mass is affected by the falling force action of the toppling deformation. The 700-900m elevation area of the bank slope is a more stable region, the slope slip and the toppling two kinds of damage mixing areas, and the rock layers have two different failure modes. The bank slope above the 900m elevation is the basic stable area, and the rock mass falls down to provide the sliding force; after the reservoir water action, the area under the 700m elevation below the bank slope is affected by the area due to the bank slope. With the function of reservoir water, the rock mass is weakened and the strength is reduced, the local shear deformation and deformation occur, from the stable area to the unstable region, the slope deformation is dominated by horizontal slip deformation, and the 700-900m elevation area of the bank slope is affected by the lower sliding deformation and the uptoppling deformation, which is changed from the stable area to the under stable zone, and the slope of the bank slope is above the 900m elevation area. The region is less affected by the reservoir water, but the stability of the slope in the front of the slope is slightly changed, so it is still the basic stable area, and the deformation is mainly vertical to the toppling deformation. (4) the slope deformation of the bank slope, the shear deformation interface height is proportional to the mechanical parameters of the bedding, the better the mechanics parameters of the bedding, the higher the height of the deformation interface, the bank slope. The smaller the toppling deformation area is, the influence of the interfacial elevation is greater than the cohesion by the inner friction angle of the bedding. When the cohesion is less than 50kPa and the internal friction angle is less than 30 degrees, the most area of the bank slope will have toppling deformation, and the shear deformation zone is only distributed in the 530m-546m elevation section. When the internal friction angle is greater than 35 degrees, the most area of the bank slope is mainly shear deformation. The toppling deformation is distributed only in the area above the 1000m elevation; (5) the early deformation mode of the bank slope is mainly increased by the number of toppling deformation strips, the slope of the bank slope is smaller and the deflection range is less than 8 degrees, and the subsequent slope deformation of the bank slope will be the dumping deformation strip, the angle of the dumping deformation is increasing synchronously, and the bank slope is under the influence of no external factors. There will be 140 pieces of dumping strip and the evolution of the area near the angle of 30 degrees. (6) the stability of the bank slope decreases obviously after the action of the reservoir water, the new evolution path is slightly offset by the original evolution path to the tilting strip coordinate axis, and the effect of the reservoir water on the slope evolution path of the bank slope has no obvious effect, only by reducing the mechanical parameters of the slope soil and soil, making the bank slope before the slope. The shear strength of the section is reduced and the overall stability coefficient of the bank slope is reduced. Four, the characteristic value of the dumping deformation and the evolution mechanism of the bank slope (1) the mechanical strength parameters of the slope rock mass are determined by the comprehensive Hoek-Brown criterion and numerical test on the basis of the microscopic parameters of the bank rock block, and the evolution process of the slope deformation of the bank slope is simulated with the PFC software. A variety of characteristic values of stress field, displacement field and energy field are obtained, and the front part of the bank slope is subjected to shear deformation under horizontal stress, and the back part of the bank slope is inverted under vertical stress. (2) the analysis of the evolution characteristics of the stress field shows that the bank slope is in high stress state at the foot valley of the slope. The stress field in the shallow slope is mainly vertical stress, the horizontal stress, the vertical stress and the shear stress gradually increase along the depth, and the difference of stress field in different regions and different evolutional periods is significant. (3) the analysis of the evolution characteristics of the displacement field shows that the surface is mainly the horizontal deformation and the horizontal displacement is in the elevation 900-1050m section displacement value and The growth rate is the largest, and the direction of the slope is gradually decreasing. The horizontal displacement of the top is larger than the slope foot. The vertical displacement of the surface is similar to the horizontal displacement, and the front part of the bank rises because of the shear deformation; the deep displacement in the middle of the bank slope increases with the depth with the depth of the slope. (4) the evolution of the energy field. The characteristic analysis results show that the strain energy is maximum in the evolution process, the friction energy is second, the kinetic energy is minimum, the energy is gradually increased at any time, the energy steep rise interval is at 100 thousand -30 million step. According to the energy field evolution characteristic curve, the evolution process of the slope collapse deformation is divided into the shear deformation stage, the main toppling fracture surface is through the pass order. There are three stages of secondary collapse, fracture surface development and so on. (5) at the shear deformation stage, the horizontal stress in the deep slope of the bank slope increases sharply, and the closer to the slope is.
【学位授予单位】：中国地质大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU43

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