层状节理岩体高边坡地震动力破坏机理研究

发布时间：2018-06-25 13:49

本文选题：边坡 + 地震　；参考：《中国地质大学》2013年博士论文

【摘要】：地震诱发的层状节理岩体高边坡破坏是一种常见的的自然地质灾害,破坏范围极大,破坏力极强。对于其地震动力破坏机理的研究,涉及到多学科的交叉,一直是科学界的研究重点和难点之一。目前的研究手段和研究方法多数借鉴于对土质边坡地震动力破坏机理研究的成果,不能很好的反映出层状节理岩体的结构特征和动力变形破坏特点。本文从层状节理岩体的物理力学特征入手,以结构面网络控制理论为核心思想,综合利用工程地质分析法、岩体力学理论、岩石断裂力学理论、物理模型试验手段和数值模拟试验手段,分别针对顺层节理岩体高边坡、逆层节理岩体高边坡和近水平层状节理岩体高边坡的地震动力破坏机理进行了系统的研究探索,主要的研究结论如下：以结构面网络控制理论为指导思想,系统分析了三种层状节理岩体高边坡的岩体结构面网络发育特征和物理力学性质,将结构面分为层面和正交次级节理面两大类,认为层面和正交次级节理均存在着贯通部分和非贯通部分;着重强调了正交次级节理对岩体边坡地震动力稳定性的影响；指出岩体结构面的非贯通部分所具有的强度对岩体边坡地震动力稳定性的贡献十分显著。运用岩体力学理论和岩石断裂力学理论,通过理论推导和对前人试验结果的分析,明确了岩石材料内部的微裂纹只能产生Ⅰ型张拉破坏,而所谓的岩石裂纹Ⅱ型剪切破坏,实际上是由无数微观的Ⅰ型张拉破坏面连接而成的细观破坏面,其尺度已经超出经典材料断裂力学微观尺度研究范畴,不属于真正意义上的裂纹Ⅱ型剪切破坏,从而说明岩石断裂力学实际上是一门介于微观和宏观尺度之间的材料科学。推导了层状岩体层面内部细观裂纹扩展贯通的断裂力学计算公式和破坏判据,研究了在不同应力条件下和不同的层面强度条件下层面内部裂纹扩展贯通的规律。研究结果证明,层面的强度与受力状态相关,并且层面强度与完整岩块强度的比值会影响层面的扩展模式。改进了层状岩体内部正交次级节理形成机制构造力学模型,并分析了不同构造力学条件下正交次级节理扩展的断裂力学机制。利用岩石断裂力学理论从力学角度系统研究和总结了为何层状岩体中的正交次级节理无法穿透层面切割多层岩石。研究结果表明,产生这种现象的原因主要有：正交次级节理无法穿透已经产生贯通的层面；由于非贯通层面断裂韧度远低于完整岩块断裂韧度,因此正交次级节理在扩展至与非贯通层面交汇时,无论处于何种应力状态,均会优先沿层面延伸方向产生扩展,使层面逐渐贯通,而无法切穿非贯通层面进而切割多层岩石。总结了顺层、逆层和近水平层状节理岩体高边坡地震动力破坏基本特征,改进了各类边坡的地震动力破坏模型。以结构面网络控制理论为指导,分别对顺层、逆层和近水平层状节理岩体高边坡在地震动力作用下内部层面和正交次级节理面的破坏模式进行了详细的分类研究,通过研究证明,对于顺层节理岩体高边坡,在水平地震动力作用下其内部非贯通层面部位也可能处于受拉应力状态,产生张拉破坏,并非只能产生剪切破坏。通过分析指出,贯通结构面由于胶结或填充作用所具有的微小抗拉强度不能在动力破坏分析过程中被忽视,因为当抗拉强度丧失后,贯通结构面的抗剪强度也会显著减小。为此,提出了考虑贯通结构面动力破坏过程中抗拉强度与抗剪强度关系的改进Mohr-Coulomb破坏准则。使用相似材料制作了含有非连续的层面和非贯通的次级节理顺层和逆层岩质边坡物理模型,并对其进行了离心机动力试验研究。对岩石相似材料的常规试验和裂纹扩展试验结果证明本文所设计的岩石相似材料制作方法和闭合接触层面和次级节理制作方法能够较好的反映真实层状节理岩体的物理力学特性。岩石相似材料采用石膏和细砂及水的混合物通过标准化的制备方法制成,其物理力学特性与沉积砂岩近似：设计了新的工艺和新的方法,首次实现了完全闭合接触的贯通层面的制作；实现了层面非贯通部位的精确位置控制和较为精确的强度控制；设计并改进了离心机试验系统,其中改进了试验加载平台,使其适用于岩体边坡模型动力试验；设计了新的裂隙扩展监测装置,用于监测边坡层面的准确破坏时刻。离心机模型试验结果证明：①边坡地形放大效应与地震动力输入频率和振幅有关,并分析推断产生这种现象的原因为边坡阻尼的影响,阻尼不是常数,与震动频率有关,并且阻尼越大,边坡的地形放大效应越明显；②层状岩体中广泛发育的正交次级节理对层状岩质边坡的动力响应和动力破坏均存在显著的影响,含有正交次级节理的边坡模型动力稳定性小于不含有正交次级节理的边坡模型。完善了使用非连续性介质模拟方法和连续性介质模拟方法进行层状节理岩体高边坡建模进行耦合计算的原理及具体实现方法。其中非连续介质建模部分采用PFC2D软件,连续性介质建模部分采用FLAC软件。系统研究了由颗粒集合体粘结而成的PFC2D岩块模型中颗粒细观参数与模型宏观参数之间的关系；改进了非贯通Smooth Joint接触模型破坏准则,设计了两种在PFC2D层状岩体模型内部表达层状岩体内部正交次级节理的方法,即通过折减层间岩块强度的隐式方法,和使用改进的Smooth Joint接触模型显式添加正交次级节理的方法：建立了PFC2D层状岩体模型,通过对模型进行单轴抗压试验,并与岩石断裂力学理论计算结果相对比,证明了该模型的适用型。分别建立了顺层、逆层、近水平层状节理岩体高边坡PFC2D/FLAC耦合计算模型,进行了边坡地震动力破坏过程数值模拟,分析了各类边坡地震动力破坏的基本模式,并针对层状节理岩体中层面和正交次级节理的参数对边坡地震动力破坏过程的影响进行了试验研究,研究结果如下：在地震动力破坏过程中,顺层节理岩体边坡主要沿层面与正交次级节理组合而成的破坏面产生滑动破坏。内部非贯通层面不只会产生剪切破坏,而且会产生张拉破坏；正交次级节理主要产生张拉破坏,几乎不存在剪切破坏。非贯通层面部分的强度和层面贯通率对顺层边坡地震动力稳定性的影响十分明显,贯通层面摩擦角的影响较小；非贯通正交次级节理强度和节理间距对边坡地震动力稳定性、破坏模式、破坏范围均有着显著的影响：贯通正交次级节理的摩擦角对边坡地震动力过程几乎不产生影响。试验结果证明,层状岩体中广泛发育的正交次级节理对顺层岩体边坡地震动力破坏模式影响显著,在进行顺层节理岩体边坡地震动力稳定性分析时,必须考虑正交次级节理的发育对其破坏模式和稳定性的影响。实验结果还证明,顺层岩体边坡地震动力顺层滑动破坏机理的传统理论存在着漏洞,顺层边坡内部的层面,即使在如本文所施加的水平地震动力作用下,仍然可以产生张拉破坏,因此在对边坡地震动力稳定性的研究中,必须考虑层面抗拉强度的影响。试验中顺层节理岩体高边坡的动力破坏是一个渐进的过程,随着地震动力输入的增强,边坡破坏区域由表层区域逐渐向边坡内部扩展,边坡在破坏过程中内部会形成多条贯通破坏面,破坏区域的岩体在地震动力作用过程中也会产生内部的解体。因此,传统的只针对某一指定潜在破坏面进行的顺层边坡地震动力稳定性分析,只能计算出边坡沿着该指定破坏面破坏的情况下的稳定性,但这不能完整的表达边坡的实际动力稳定性。为此,设计了一种新的顺层节理岩体边坡动力稳定性判定方法,采用两个基本参数进行破坏判别：①边坡内部形成首条贯通破坏面所需的地震动力输入强度；②首条贯通破坏面所围破坏区域大小。该判定方法既可以判断边坡的动力稳定性,又可以判断边坡失稳后破坏范围的大小。在地震动力破坏过程中,逆层节理岩体高边坡主要产生倾倒破坏,内部层面主要产生剪切破坏和张拉破坏,以剪切破坏为主,张拉破坏所占比例很小,并且均集中于逆层边坡坡体顶部位置。坡顶岩层主要产生沿正交次级节理的张拉破坏,形成转动位移,产生宏观的倾倒；而坡底的正交次级节理既会产生张拉破坏,也会产生剪切破坏,坡底岩层产生的转动位移很小,而滑动位移趋势明显。非贯通层面部分的强度和层面贯通率对逆层边坡地震动力稳定性的影响十分明显,而贯通层面部分的抗剪强度的影响较小。非贯通正交次级节理强度、贯通正交次级节理抗剪强度、正交次级节理间距三个参数均会对边坡地震动力稳定性产生一定的影响,但影响的程度十分有限。在地震动力作用下逆层边坡坡顶岩层内的正交次级节理首先产生张拉破坏,使顶部岩体产生倾倒趋势,然后才是边坡底部岩层内部的正交次级节理产生剪切破坏和张拉破坏,使底部岩体形成贯通破坏面,产生滑动位移。而对逆层边坡的传统静力学分析认为在静力条件下,边坡底部岩体首先产生破坏,导致上覆岩体失去支撑形成倾倒破坏。这一破坏顺序的差别充分反映出了正交次级节理的存在对边坡地震动力破坏过程的影响,并体现出了逆层边坡静力破坏与动力破坏过程的区别。在地震动力破坏过程中,近水平层状节理岩体边坡内部岩体产生了大量的渐进式破坏,其中包含了张拉破坏和剪切破坏,以张拉破坏为主。岩体首先产生大量的近竖直方向延伸的宏观张拉裂缝,随着这些裂缝数量的增加和密度的增大,相互连接形成宏观的剪切破坏面,构成了圆弧状的破坏面。随着正交次级节理强度的提升,边坡的地震动力稳定性相应提升。边坡表层破碎岩体的厚度在很大程度上控制着边坡产生整体破坏的破坏范围,随着厚度的增大,破坏范围相应增大。贯通层面抗剪强度对边坡地震动力稳定性、动力破坏过程的影响非常小。随着层面倾角的变化,边坡逐渐从顺层缓倾过渡到逆层缓倾,在相同地震强度作用下边坡地震永久位移随着倾角的减小逐渐减小,并呈现近似指数关系。因此,在进行近水平层状节理岩体边坡地震动力稳定性分析过程中,无法找出一个固定的永久位移阀值,来统一判断不同倾角边坡的临界失稳状态。选取在5.12汶川地震中产生破坏的四川省北川县孙家园滑坡为计算实例,建立其FLAC/PFC2D耦合模型进行地震动力破坏过程数值模拟。模拟结果显示,孙家园滑坡在汶川地震作用下,先后经历岩体内部破损、边坡局部崩滑、边坡大面积失稳、破坏体解体形成岩石碎屑流、沿山体高速运移刮铲山体表层破损岩体、减速堆积堵塞河道几个阶段。计算结果与实际情况符合程度较高。
[Abstract]:The destruction of the high slope of the earthquake induced layered jointed rock mass is a common natural geological hazard, which has great damage range and very strong destructive force. It is one of the key and difficult points for the scientific community to study the mechanism of its earthquake dynamic failure, and it is always one of the key and difficult points in the scientific circle. The results of the study of the seismic dynamic failure mechanism of the soil slope can not well reflect the structural characteristics of the layered jointed rock mass and the characteristics of the dynamic deformation and failure. This paper, starting with the physical and mechanical characteristics of the layered jointed rock mass, takes the network control theory of structural surface as the core idea, comprehensive application of engineering geological analysis, rock mechanics theory and rock The fracture mechanics theory, the physical model test means and the numerical simulation test means to study the seismic dynamic failure mechanism of the high slope of the bedding jointed rock mass, the high slope of the inverse jointed jointed rock mass and the high slope of the near horizontal jointed rock mass, and the main research conclusions are as follows:
Based on the theory of structural plane network control, the network development characteristics and physical and mechanical properties of the rock mass structure surface of three kinds of layered rock mass high slope are systematically analyzed, and the structure surface is divided into two categories, the layer and the orthogonal secondary joint surface, and it is considered that the layer and the orthogonal secondary joint are both in the through and non through parts. The influence of the orthogonal secondary joint on the seismic dynamic stability of rock slope is discussed, and it is pointed out that the strength of the non penetrating part of the rock mass has great contribution to the seismic dynamic stability of the rock slope.
By means of rock mechanics theory and rock fracture mechanics theory, through theoretical deduction and analysis of previous experimental results, it is clear that the micro cracks within the rock material can only produce type I tensile failure, and the so-called rock crack type II shear failure is actually a mesoscopic failure surface connected by a number of microcosmic type I tensile failure surfaces. Its scale has exceeded the microscopic scale of fracture mechanics of classical materials and does not belong to the true sense of crack type II shear failure, which indicates that rock fracture mechanics is actually a material science between microcosmic and macroscopic scale. The formula and failure criterion are used to study the law of crack propagation through the internal crack under different stress conditions and different layers of strength. The results show that the strength of the layer is related to the stress state, and the ratio of the strength of the layer to the strength of the complete rock will affect the expansion mode of the layer. The structural mechanics model of the formation mechanism of the stage joints is made and the fracture mechanics mechanism of the orthogonal secondary joint expansion under different tectonic mechanics is analyzed. By using the rock fracture mechanics theory, the paper studies and summarizes the reason that the orthogonal secondary joint in the layered rock can not cut through the layer surface to cut the multilayer rock. The main reasons for this phenomenon are as follows: the orthogonal secondary joint can not penetrate into the penetrated layer; because the fracture toughness of the non penetrating layer is far lower than the fracture toughness of the intact rock, the orthogonal secondary joint will extend to the non through layer, and in any stress state, it will give priority to the expansion along the extension direction. The exhibition gradually penetrated the layers, and could not cut through the non penetrating layers to cut the multi-layered rock.
The basic characteristics of the seismic dynamic failure of the high slope of the bedding, reverse and near horizontal jointed rock masses are summarized, and the seismic dynamic failure models of various slopes are improved. With the guidance of the structure surface network control theory, the internal and orthogonal secondary joints of the high side slope of the bedding, reverse and near horizontal jointed rock mass are respectively under the action of seismic dynamic action. The failure mode of the surface is studied in detail. Through the study, it is proved that for the high slope of the bedding jointed rock mass, it may also be in the state of tensile stress under the action of horizontal seismic dynamic force, which produces tensile failure and not only produces shear failure. Through analysis, it is pointed out that the perforated structure surface is due to cementation or filling. The micro tensile strength of the filling can not be ignored in the process of dynamic failure analysis, because when the tensile strength is lost, the shear strength of the perforated structure will be reduced significantly. Therefore, an improved Mohr-Coulomb failure criterion is proposed to consider the relationship between the tensile strength and the shear strength during the dynamic failure process of the perforated structure.
Using similar materials, a physical model of a secondary and non penetrating secondary jointed and reverse rock slope is made, and a centrifuge dynamic test is carried out. The conventional test and crack propagation test of similar rock materials prove the method of making the similar material and the closed contact layer designed in this paper. The surface and secondary joint method can better reflect the physical and mechanical properties of the real layered jointed rock mass. The rock similar material is made of a standard preparation method by using a mixture of gypsum and fine sand and water through a standardized preparation method. The physical and mechanical properties of the rock are similar to the sedimentary sandstone. A new process and new method are designed and the complete closure is realized for the first time. The production of close contact layer is made, the precise position control and the precise strength control are realized, and the centrifuge test system is designed and improved, which improves the test loading platform, makes it suitable for the dynamic test of rock slope model, and designs a new crack extension monitoring device for monitoring edge. The results of the centrifuge model test prove that the magnification effect of the slope is related to the frequency and amplitude of the seismic dynamic input, and the reason is that the cause of this phenomenon is the influence of the slope damping. The damping is not constant, which is related to the frequency of the vibration, and the greater the damping, the greater the terrain magnification effect of the slope is. There is a significant influence on the dynamic response and dynamic failure of the layered rock slope, and the dynamic stability of the slope model containing the orthogonal secondary joint is less than that of the slope model without the orthogonal secondary joint.
The principle and concrete realization method of coupling calculation with non continuous medium simulation method and continuous medium simulation method for high slope modeling of layered jointed rock mass are perfected. The modeling part of discontinuous medium uses PFC2D software and FLAC software is used in the modeling part of continuous medium. In the PFC2D rock mass model, the relation between the fine parameters of the particle and the macroscopic parameters of the model, improved the failure criterion of the non through Smooth Joint contact model, and designed two methods to express the orthogonal secondary joint inside the layered rock mass in the PFC2D stratified rock mass model, that is, the implicit method of reducing the strength of the rock mass between the layers and the use. The improved Smooth Joint contact model is used to explicitly add the orthogonal secondary joint. The PFC2D layered rock mass model is established. Through the uniaxial compression test of the model, the model is compared with the rock fracture mechanics theory. The model is proved to be applicable.
The PFC2D/FLAC coupling calculation model of the high slope of the bedding, reverse and near horizontal jointed rock mass is established respectively, and the numerical simulation of the seismic dynamic failure process of the slope is carried out. The basic modes of the seismic dynamic failure of various slopes are analyzed, and the seismic dynamic failure of the slope in the stratified jointed rock mass and the secondary joints of the normal intersection is destroyed. The effect of the process is studied. The results are as follows:
In the process of seismic dynamic failure, the rock slope of the bedding jointed jointed rock mass is mainly caused by the failure surface which is combined with the orthogonal secondary joint. The internal non perforation layer will not only produce shear failure, but also produce tensile failure; the orthogonal secondary joint mainly produces tensile failure and almost no shear failure. The influence of the strength and the penetration rate on the seismic dynamic stability of the bedding slope is very obvious, and the friction angle of the penetration level is less. The non penetrating orthogonal secondary joint strength and joint spacing have significant influence on the dynamic stability of the slope, the failure mode and the damage range, and the friction angle through the orthogonal secondary joint is carried out. It has almost no effect on the seismic dynamic process of the slope. The experimental results have proved that the widely developed orthogonal secondary joint in the layered rock mass has a significant influence on the seismic dynamic failure mode of the bedding rock slope, and the failure mode of the development of the orthogonal secondary joints must be considered when the seismic dynamic stability of the bedding jointed rock slope is analyzed. The experimental results also prove that there is a loophole in the traditional theory of the failure mechanism of the sliding failure of the bedding rock slope, and the level of the inner side of the bedding slope can still produce tensile failure even under the effect of the horizontal seismic dynamic exerted in this paper. Therefore, it is necessary to study the seismic dynamic stability of the slope. The dynamic failure of the high slope of the bedding jointed rock mass in the test is a gradual process. With the enhancement of the seismic dynamic input, the slope failure region gradually extends from the surface area to the side of the slope, and a number of perforated failure surfaces will be formed inside the slope during the failure process, and the rock mass in the region is destroyed in the earthquake. In the process of dynamic action, the internal disintegration will also be produced. Therefore, the analysis of the seismic dynamic stability of the bedding slope, which is only aimed at a certain specified potential failure surface, can only calculate the stability of the slope under the specified failure surface, but this can not fully express the actual dynamic stability of the slope. For this reason, the design of the slope can not be fully expressed. A new method for determining the dynamic stability of the rock slope of the bedding jointed rock mass is made, and two basic parameters are used to judge the failure of the slope. (1) the seismic dynamic input strength required for the formation of the first perforated failure surface in the slope; It can be used to judge the size of the failure range after the slope is unstable.
In the process of seismic dynamic failure, the high slope of the rock mass of the reverse layer mainly produces toppling failure, and the internal layer mainly produces shear failure and tensile failure, which is mainly shear failure, and the proportion of tensile failure is very small, and it concentrates on the top position of the reverse slope slope. The top rock formation mainly produces tensile failure along the orthogonal secondary joints. The rotation displacement of the slope is formed, and the orthogonal secondary joints at the bottom of the slope not only produce tensile failure, but also produce shear failure. The rotation displacement of the slope bottom rock is very small and the sliding displacement trend is obvious. The strength and the penetration rate of the non penetrating layer have a very obvious influence on the seismic dynamic stability of the reverse slope. The shear strength of the cross section is less. The non through orthogonal secondary joint strength, through the orthogonal secondary joint shear strength, and the orthogonal secondary joint space three parameters will have a certain influence on the slope seismic dynamic stability, but the degree of influence is very limited. The orthogonal secondary joint first produces tensile failure, which causes the toppling tendency of the top rock mass, and then is the shear failure and tensile failure of the orthogonal secondary joint in the bottom rock of the bottom of the slope, making the bottom rock forming a perforated failure surface and producing sliding displacement. The rock mass at the bottom of the slope is first damaged, which causes the overlying rock mass to lose its support and form the toppling failure. The difference of the destruction sequence fully reflects the influence of the existence of the orthogonal secondary joint on the seismic dynamic failure process of the slope, and shows the difference between the static failure and the dynamic breaking process of the reverse slope.
In the process of seismic dynamic failure, the rock mass in the rock slope of the near horizontal jointed rock mass has a large number of progressive failure, including tensile failure and shear failure, which is dominated by tensile failure. The rock mass first produces a large number of near vertical directions.
【学位授予单位】：中国地质大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU45

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