【作者】 赵家成；

【导师】 殷坤龙；

【作者基本信息】 中国地质大学 ， 岩土工程， 2013， 博士

【摘要】 岩体的破坏是岩体结构面临界状态的过渡,对于如滑坡这样的灾害地质体,它的破坏过程也取决于结构面破坏状态的发展。“量变是质变的前提和必要准备,质变是量变的必然结果”,地质灾害体滑动这一质变过程必然来自其结构面局部破坏过程的积累和准备。而结构面的非连续分布是其普遍特征,这与传统力学模型中的均一化本构模型存在差异,采用传统力学模型难以描述具有非连续结构特征的结构面的完整的演化过程,因此有必要从试验手段和试验方法方面探索研究非连续分布结构结构面的新方向。从试验手段来讲,当要研究的结构面的非连续分布的尺度较大时,应设法创造出一种实验条件,能够详尽的观察或测量到一个或若干个非连续结构的演变过程。而传感器技术的发展已经能够提供在一个测量面上同时测量二维(甚至六维)方向力的传感器,可以在这个测量面上直接测量到摩擦系数,如果将这样的传感器排列成一个测力矩阵,那么一个剪切面就被分隔成若干个小的剪切面,并且每个剪切面法向力和剪切力可以同时测量到,这样一个剪切面单元的受力情况就可以完成独立的测量。本研究从剪切力学参数的量测方式入手,通过建立一个由多维应力传感器组成的测量矩阵,形成一种可以观察剪切面局部剪切力变化的试验手段,并在此基础上研究非连续分布结构面在剪切过程中,不同结构面区域间的应力分配关系,观察结构面破坏过程的应力应变过程。同时结合颗粒流模拟结果,建立非连续分布结构面的剪切破坏过程的理论模型。和岩体结构一样,岩体结构面的规模大小差别很大,不同规模的结构面的延伸范围、厚度、分布规律都存在着巨大的差异。如果从工程尺度这个角度出发,一般需要研究探索的岩体结构面都应是Ⅱ级和Ⅲ级结构面。针对这样规模的结构面,许多研究是将结构面局部化、均质化,在此基础上进行了结构面力学性能及变形性能的研究。目前结构面力学模型针对结构面表面粗糙状态进行了概化或统计,并在此基础上考虑不同因素的影响建立了岩体结构面的力学变形模型。千将坪滑坡是一个典型岩质滑坡,发生滑动的主滑面属于Ⅱ类结构面,滑动前结构面夹层物质的组成、厚度以及含水状态都存在巨大差异,其差异性并不能完全用连续力学模型概括。其滑带结构面的非连续包括(1)滑带泥化层厚度的非均匀分布。平硐顶端结露的长度近20米S6层间剪切错动泥化带,厚度范围20～50cm,统计平均厚度为12.74cm,厚度变化标准差为10.67cm,标准差与平均值的比值达到0.838；(2)滑带的物质组成的非均匀分布。S6泥化层有两种泥物质组成,一种是灰黑色粘土,一种是黄褐色粉质粘土,两种泥化物的力学参数差异较大,两种泥化物或独立存在,或相互交错,多数情况下可以区分出两者的区域及边界；(3)结构面干湿状态的非连续分布。结构面附近的含水状态差别很大,与数值模拟研究滑坡机理时假定的结构面含水状态均匀一致存在较大差别。依据对典型滑坡地质体中的关键结构面的观察和分析,将工程岩体中控制性结构面的结构概化为两个具有一定粗糙或起伏的接触面之间有填充夹层的结构面模型,并将结构面的起伏度、夹层厚度、夹层物质组成作为反映结构面非连续特征的特征参量,研究这些特征参量对结构面抗剪力学性能的影响。研究岩土材料包括结构面的抗剪力学性能,主要采用的是直剪仪,传统的直剪仪是通过上下剪切盒的相对错动来实现对试样的剪切作用,一次剪切试验形成一个剪切面并只能测量这个剪切面的法向力和切向力,对于剪切面内部的应力分布是无法探知的。而多维力传感器可以同时测量其受力端三维方向的受力,将多个多维力传感器组装成一个受力矩阵,并把这个受力矩阵作为结构面中一个岩体界面,就可以实现在一次剪切过程中对剪切面的不同局部位置的应力状态进行测量。本章采用6个smart300-5000-2多维力传感器,smart300-5000-2多维力传感器采用的是E型膜结构作为受力弹性体结构,传感器两个水平向的测力量程为±2500N,垂直向测力量程为±5000N。根据smart300-5000-2多维力传感器的结构特点,以及在一个剪切面内测量局部剪切应力的应用要求,需要将smart300-5000-2多维力传感器的受力面板排列成一个完整的受力平面,并把这个平面作为模拟岩体结构面的一个接触面。试验中将多维力传感器排列成6×1的受力矩阵。为了构建一个较大的剪切平面,将组装好的受力矩阵固定在1.2米x0.5米的钢结构支架上,然后在受力矩阵周围砌筑混凝土,混凝土表面与受力表面齐平,这样混凝土表面与受力矩阵平面共同组成了一个面积为1.2米x0.5米剪切平面。利用多维力测力平台研究结构面的应力应变关系,包括法向压缩过程中的法向应力与法向应变的应力应变关系和剪切过程中的剪切应力与法向应力的关系。研究表明法向压缩过程中,法向应力在不同区域内会因为夹层材料的变形刚度差异形成不均匀的分配关系,试验验证了对这种分配关系的理论推导。在剪切过程中的剪切应力与法向应力的关系时,通过试验发现在剪切过程中尽管总的结构面平面内法向力保持稳定,局部单元上依然反映出较为显著的法向应力调整,各个测力单元上测到的局部法向力会出现成对的法向力变化,与力学中的力偶概念相似,因此称之为局部法向应力的“力偶变化现象”。其大体有以下几个特征：(1)出现力偶变化现象通常是法向力增加的单元在顺剪切方向上先出现,法向力减少的单元后出现：(2)出现力耦变化现象的单元可能相邻,但通常不是相邻单元,而是会出现一个间隔单元,间隔单元上测量的法向力与其他单元一样保持稳定：(3)出现力偶变化的单元并不是固定的单元。根据这一现象的特征,结合多相流扩散模型,该现象可以解释为当剪切过程开始后,夹层材料会在剪切作用下产生沿结构面的运动。但是结构面每处夹层物质迁移的数量和速度存在差异,因而导致在某些局部,夹层物质会增多,产生挤胀,使局部法向力增加；相对应的部分区域的夹层物质减少,形成塌缩,导致局部法向应力降低。在剪切试验中,研究了起伏角以及夹层材料物质组成对剪切力学过程的影响。对比起伏角分别为60°、45。、30°时各传感器测得的法向-切向分力关系,可以发现起伏角越大,传感器测得的法向-切向分力关系图出现横向变化的点增多,法向力的变化范围也增大,表明起伏角的增加会增加局部单元法向应力调整的几率。在研究夹层物质对结构剪切力学性能影响机制的试验中,调整夹层材料碎石含量为20%、40%、60%和80%,对比剪切试验成果可以得出以下结论：(1)随着碎石含量的增多切向应力变化范围明显增大；(2)随着碎石含量的增多出现法向应力调整的单元增多,应力调整的范围增大；(3)碎石含量较大时,一些单元上法向应力与切向应力的关系表现接近于摩尔库伦定律。根据对软弱结构面主要结构特征的相关研究,选取其中对其剪切力学特性影响较显著的特征结构因素,将软弱结构面概化成包括上下岩体结构和中间软弱夹层结构,上下岩体与软弱夹层的接触面的粗糙结构概化为有一定倾斜角度(结构面起伏角)、有一定高度的锯齿状结构,软弱夹层填充上下岩体接触面之间的空间。采用PFC2D(Particle Flow Code in2Dimensions)颗粒流程序建立具有粗糙结构的软弱结构面的颗粒离散元模型并进行结构面剪切过程的模拟。PFC2D以圆形(圆碟)作为最基本的颗粒单元,通过构建由大量圆形颗粒组成的颗粒集模型并模拟圆碟的运动及其相互作用来模拟宏观结构的力学过程。在颗粒单元的基础上,通过循环的运动.力学计算具有复杂变形模式的实际问题。采用PFC2D建立的结构面模型在两个结构要素上有变化。一是起伏角是在同一宽度范围内布置不同锯齿齿数1齿、2齿、3齿、4齿、5齿和6齿,对应起伏角3.2°、6.3°、9.5°、12.5°、15.5°和18.4°；另一个是夹层厚度,分别取0.6倍齿高、1.0倍齿高、1.5倍齿高、2.0倍齿高和2.5倍齿高作为夹层厚度。剪切模拟试验结果显示夹层厚度为0.6倍齿高、1倍齿高和1.5倍齿高时,具有不同结构面起伏角的结构面的综合剪切强度差异较大,而夹层厚度为2倍齿高以及2.5倍齿高时,不同结构起伏角的结构面剪切强度较为接近,表明当夹层厚度小于1.5倍齿高时,结构面表面起伏结构才会对剪切强度产生影响,且结构面起伏角较小时,剪切强度较小,结构面起伏角较大时,剪切强度较大。如果夹层厚度大于2倍齿高,结构面的综合抗剪强度与结构面起伏结构无显著关系,并且结构面的综合抗剪强度参数与夹层材料的抗剪强度参数较为一致,表明当夹层厚度超过一定厚度,结构面的整体抗剪强度受夹层材料的抗剪强度参数的控制。分析模拟试样剪切过程中的应力应变关系,可以发现当法向荷载较大时,结构面抗剪强度由峰值强度到残余强度的应力跌落绝对值可能有一定的增加,但应力跌落比值却是普遍减小了。联系到大型滑坡的启动过程也是其滑带结构面剪切破坏过程,那么当滑坡启动后,滑带抗剪强度跌落越大,意味着滑坡体最终释放的滑动能力越大,其成灾的可能性越大。由此可以推论,对于大型滑坡,滑坡体的厚度可能是决定滑坡体是否成为致灾体的关键因素；研究法向位移和剪切位移之间的关系,同样发现结构面剪胀变形率(由剪胀角反映)的变化与夹层厚度有关。当夹层厚度小于一定厚度,结构面的起伏结构对剪胀角产生影响,其阀值也大体为1.5倍结构面平均起伏高度。更多还原

【Abstract】 Rock failure is a transition for the critical state of rock mass joint, As for Geological hazard such as the landslide, the failure process also depends on the development of joint failure state."Quantitative change is the premise and necessary preparations for qualitative change, qualitative change is the inevitable result of quantitative change", for geological hazard body sliding, this qualitative change process must derive from the local failure process of preparation and accumulation. And non-continuous distribution of joints is a common feature of itself, which is different from the traditional mechanical model of the constitutive model of homogenization, it’s difficult to describe the whole evolution process of the joints with discontinuous structure feature applying the traditional mechanical model, so it is necessary to explore the new direction of non-continuous distribution joints with research of test method.For the experiment means, when the scale of non-continuous distribution of the joints to study is much larger, we should try to create an experimental condition to obtain a detailed observation or measurement of non-continuous joints evolution one or more. However, the development of sensor technology has been able to provide a two-dimensional directional force measurement simultaneously in one measuring plane (or even six dimensional). Then the friction coefficient in the measurement of the surface can be directly measured. If such a sensor arranged in a force measuring matrix, then a shear surface is divided into a plurality of small shear surface, and in each shear surface, normal force and shear force can be measured at the same time. Measurement of mechanical conditions in such a shear plane unit can be completed independently.This study based on the measuring methods of shear mechanical parameter, forming a way to observe changes of local shear stress in structural surface by creating a measurement matrix with multidimensional force sensor. Based on which we study the regional stress distribution of different structural plane in the process of the shearing in non-continuous joints, and observe mutation process in the process of structural joints failure. Combined with the particle flow simulation results, a theoretical model of non-continuous distribution joints of shear failure process will be established.Same to the rock mass structure, the size of joints of rock mass varies greatly, as to joints of different size, its extension, thickness, distribution are great differences. If consider with the engineering scale, the general rock mass structure to be researched should be II grade and III grade joints. In view of such joints, joints in many researches are homogeneous, localized, on the basis of which, mechanical properties and deformation properties of joints are studied. The structure mechanical model for structure surface roughness are generalized or statistics, and on the basis of which we consider the influence of different factors and joints of rock mass deformation model were established.Qianjiangping landslide is a typical lithology landslide, the main sliding surface belongs to II type structure plane, before sliding, composition, thickness and moisture state of structure surface interlayer material are of great differences, the difference can not be completely generalized by continuous mechanical model. The slip zone structure of the non-continuous include (1) thickness of sliding layer with mud heterogeneous distribution. Footrill top condensation length nearly20meters S6interlaminar shear argillic zone, the thickness range of20-50cm, average thickness is12.74cm, thickness standard deviation was10.67cm, standard deviation and average values of the ratios reached0.838;(2) inhomogeneous distribution of material consisting of slip zone. S6mud layer has two kinds of mud material composition, a dark gray clay, the other is brown silty clay, differences between two kinds of mechanical parameters of mudstone is larger, there are two kinds of mudstone or independent, or staggered, can regional and boundary to distinguish them in most cases;(3) non-continuous distribution in joints of dry and wet conditions. Water states of structure near the surface vary greatly, there’s a big difference between the state uniform and numerical simulation of structure assumed landslide mechanism of surface water.Based on the observation and the analysis of the key geological joints of the typical landslide of engineering rock mass, the control structure of the generalized into two has the structure plane filled sandwich model between certain rough or undulating contact surface, and the structure of surface waviness, interlayer thickness, sandwich material composition reflect the structure of non-continuous characteristic parameters of continuous features, study the influence of the shear mechanical properties of these characteristic parameters.Study on mechanical properties of rock and soil including shear strength of rock joints, mainly use direct shear apparatus, the traditional direct shear apparatus is applied by the relative upper and lower shear box to realize the shearing of the specimen, one shear test can form only one shear plane and can only measure the normal force and tangential stress of the shearing surface, the inner stress distribution is unable to ascertain. The multidimensional force sensor can measure both the stress end3D stress, a plurality of multidimensional force sensor is assembled into a force matrix, and see the stress matrix as a rock interface structure, can be measured on different location of shear surface state of stress. This chapter uses six smart300-5000-2multidimensional force sensors, smart300-5000-2multidimensional force sensor is used in type E membrane structure as the force sensor elastic body structure, two horizontal force measuring range is±2500N, the vertical force measuring range is±5000N. According to the structural characteristics of smart300-5000-2multi-axis force sensor, and the measured requirements of local shear strength in a joint, it is needed to arrange smart300-5000-2multidimensional force sensors panel to form a complete force plane, and see the plane as a contact surface to simulate rock mass joint. During the experiment, multidimensional force sensors are arranged into a of6X1force matrix. In order to build a larger shear plane, the assembled force matrix is fixed on the steel structure support with1.2meters×0.5meters, then masonry concrete around the force matrix, so that the concrete surface and the stress matrix plane constitute a shear plane with area of1.2meters X0.5meters.Using multi-dimensional force platform for the research of the relationship between stress and strain, including normal compression process of normal stress and normal strain shear stress strain relations and should be in the process of shear stress and normal stress. Research shows that the compression process, the normal stress, because of deformation of sandwich material stiffness, could be distributed differently uneven in different area, it is verified that the theoretical derivation of this distribution relationship through experiment.During the process of shearing, shear stress and normal stress is found in the, although normal force of the whole structure surface plane remained stable through the test, the local unit still reflects stress adjustment in the local structure surface plane, the local normal force measured by each force measuring unit will be double changed, and similar to mechanics of couple concept, so call it "couple change phenomenon". With the following characteristics:(1) appeared couple change phenomenon, usually normal force increase unit appears firstly in the CIS shear direction, normal force reduction unit appear later;(2) force coupling phenomenon of unit may be adjacent, but usually not adjacent units, but there will be an interval unit, the measurement of normal force on interval unit remained stable;(3) couple change unit is not a fixed unit. According to the characteristics of this phenomenon, combined with the multiphase flow diffusion model, this phenomenon can be explained that when the shear process began, interlayer materials under shear move along the structure surface. But there are differences of quantitative structure surface and interlayer material migration and speed, resulting in some local area, sandwich material will increase, the bulge, the local normal force increase; sandwich material reduced in the corresponding area, then collapse, local normal stress reduced.In the shear test, study the influence of undulating angle and the interlayer material composition on the shear mechanical process. Comparison of normal-tangential component relationship for each sensor measured with undulating angle of60°,45°,30°, the test shows that when undulating angle increases, lateral changes of normal and tangential component diagram increase greatly, changes in the scope of normal force increases, indicated that the increase of undulating angle will increase probability of the local unit of normal force adjustment.In the study of interlayer material influence on the shear mechanical properties of structure, adjusting the gravel content of20%,40%,60%and80%, comparing the shear test results, we can draw the following conclusions:(1) with the increase of gravel content, range of tangential stress increases;(2) with the increase of gravel content, unit of normal stress adjustment increases, range of stress adjustment increases;(3) when the gravel content is high, in some unit, relationship between normal stress and tangential stress is close to the Mohr-Coulomb law. According to the related research on the main structural features of the weak structural plane, select the factors which influence on the shear mechanical properties significantly, the weak structural plane is generalized to include the upper-lower rock mass structure and the middle interlayer structure, the contact surface of upper-lower rock mass and weak interlayer is generalized to a sawtooth structure with certain tilt angle (undulating angle of the structure surface), a certain height, weak intercalated layer filled between the contact surface of upper and lower rocks. Using PFC2D (Particle Flow Code in2Dimensions) particle flow code to build particles discrete element model of rough structure with weak structure and to simulate the shear process. PFC2D apply round particles (disk) as the basic unit, by building particles set model which consisted of a large number of circular and interaction to simulate the mechanical process of macro structure. Based on particle unit, through the cycle of motion-mechanical, calculate practical problems with complex deformation mode.The structure surface model, established by PFC2D, changes in two structural elements. One is the undulating angle, arrange different saw-tooth number in the same range of1teeth,2tooth,3tooth,4tooth,5tooth and6tooth, corresponding fluctuation angle of3.2°,6.3°,9.5°,12.5°,15.5°and18.4°; the other one is the thickness of interlayer, take0.6times,1times,1.5times,2times and2.5times the tooth height respectively as the thickness of interlayer.Shearing simulation results show that when the layer thickness is0.6times,1times and1.5times the tooth height, comprehensive shear strength with different surface undulating angle is greatly different, while the thickness is2times and2.5times the tooth height, the shear strength of different undulating angle tend to be similar, it indicates that when the layer thickness is less than1.5times the tooth, structure surface undulating structure will have an impact on the shear strength, and when the undulating angle of joint is small, the shear strength is small, when he undulating angle of joint is larger, the larger shear strength. If the layer thickness is2times larger than the tooth height, the comprehensive shear strength of joints has no significant relationship with fluctuation structure, and the structure of the comprehensive shear strength parameters are consistent with the shear strength parameters of interlayer materials, it shows that when the interlayer thickness exceeds a certain thickness, the whole shear strength parameters of interlayer materials is controlled by the shear strength parameters of interlayer materials.Analysis the shearing stress-strain relation during simulated sample shearing process, it can be found that when the normal load is larger, the absolute value of shearing strength from the peak shear strength to the residual stress may be increased probably, but the stress drop ratio is generally reduced. Thinking of the process of large-scale landslide slip zone is the shear failure process, when the landslide start sliding, the shear strength slip zone drop more, it means that the sliding ability of landslide will finally released the bigger, the bigger possibility of disaster. It concludes that, for large landslide, the body thickness of landslide may become the key factor that decided whether to become a landslide hazard body or not.Study on the relationship between normal displacement and shear displacement, it also found that the shear-dilatancy deformation rate (as reflected by the dilatancy angle) of joint changes with the interlayer thickness. When the interlayer thickness is less than a certain thickness, the fluctuation structure has an effect on the dilatancy angle, the threshold is generally1.5times the average height of joint fluctuation.更多还原