爆破影响下岩质高边坡浅表层块体稳定性研究

摘要:岩质高边坡整体稳定性主要受软弱结构面及其组合控制,在组合有利的情况下,边坡主要发生浅表层块体失稳,开挖时的爆破振动作用是影响浅表层块体稳定的重要因素。本文以大渡河中游某岩质块状结构高边坡为例研究浅表层块体的稳定性,在总结浅表层块体失稳特征的基础上,实测爆破振动曲线,进行块体稳定性评价。研究结果表明,开挖后已失稳浅表层块体大多小于10m3,80%受软弱结构面控制,70%集中在马道下缘;实测的浅表层块体爆破振动加速度曲线显示,与邻近围岩相比,浅表层块体振动持续时间长,频率低,峰值小;等效静力法评价结果较爆破参数推算法更适用于临界失稳浅表层块体的稳定性评价。     

确定边坡潜在滑面的块体理论方法及稳定性分析

基于复杂边坡一般由多种岩性组成,且其稳定性往往受岩体结构控制,加之边坡滑面的逐步形成特点,本文提出了采用块体理论确定复杂边坡滑面位置方法,并采用Sarma极限平衡法及其它滑面形状分析了某大型边坡工程的稳定性,验证了所提方法的正确性。     

Seismic stability analysis of a rock block using the block theory and Newmark method

Seismic stability analysis of a rock block is an important issue in the field of rock mechanics and rock engineering. To solve this problem, the block theory and the Newmark method are combined, and a general method for seismic response of a rock block is introduced. First, the formation method of a three-dimensional rock block, which includes establishing a topological relationship among the block-polygon face-edge-vertex and dividing a complex block into convex subblocks, is presented, and the simplex integration method is employed to calculate the volume of a rock block and the areas of the polygonal faces. Second, the assumptions and algorithms of the general method for seismic response of a rock block are detailed. The dynamic analysis is carried out in time step. In each time step, the key technologies including analysis of the seismic force and motion mode, trial of the incremental displacement, check for the block entrance, and update of the motion parameters are performed in order. Last, two verification examples and three application examples including a wedge, a rock block of slope, and a combined rock block are used to analyze the correctness and practicality of the general method. The results show that, for a given ground motion record, the Newmark program can effectively simulate the dynamic response process of the motion mode, velocity, and safety factor of the rock block, and the permanent displacement under the earthquake action is obtained, which provides a quantitative parameter to evaluate the dynamic stability of a rock block.     

岩质边坡复合型破坏机制的改进运动单元法研究

目前运动单元法的研究主要集中于土质边坡,未涉及到岩质边坡稳定性分析问题;而岩体中孕育有不同特性的结构面,控制着岩质边坡的力学行为。为求解结构面控制作用下岩质边坡“结构面滑移-岩桥剪断”复合型破坏问题,研究了塑性滑移区节点在岩桥内和结构面上的运动约束条件,推导了含结构面的运动单元计算公式,提出了改进运动单元法。通过经典算例的对比分析,验证了改进运动单元法计算结果的准确性。研究结果表明:岩桥位置、结构面贯通度和结构面倾角是控制岩质边坡力学行为的3个主要影响因素。岩桥越接近坡顶,改进运动单元法所得安全系数越大,而Jennings法无法反映岩桥位置的影响效应。高贯通度的结构面导致岩质边坡发生“结构面滑移-岩桥剪断”复合型破坏模式,安全系数较小;而低贯通度的结构面导致完整岩石发生破坏,安全系数较大。水平或陡倾角结构面导致滑裂面穿切结构面,安全系数较大;而对于其它倾角情况下的结构面,岩质边坡发生“结构面滑移-岩桥剪断”复合型破坏模式,安全系数较小。实例应用结果说明该方法可以有效评价岩质边坡的稳定状态,可在类似工程中应用推广。     

Dynamic stability analysis of rock slope considering the strength vibration degradation of through-type rock discontinuitiesEI北大核心

考虑结构面抗剪强度震动退化效应对分析与评价岩质边坡动力稳定性具有重要意义。基于岩石动力试验获取了多因素影响的结构面强度震动退化系数方程,结合极限平衡理论和动态矢量法原理,以UDEC程序作为计算引擎,采用其内置Fish语言编程实时刷新结构面强度特性参数和捕获任意地震历时时刻边坡地震惯性力,并以最小平均安全系数法求解边坡最终动力稳定性评价指标值,从而提出了一种考虑结构面强度震动退化的边坡动力稳定性系数动态算法。研究表明:结构面强度震动退化系数是取决于岩块间循环剪切次数、循环剪切幅度及相对运动速度响应值的动态变量;将该算法应用于含贯通型平直状结构面边坡动力稳定性算例中,其分析结果表明,动力作用时程内考虑结构面强度震动退化的边坡动力稳定性系数较未考虑该效应时的系数衰减更为明显,即前者计算结果更符合一般性自然规律,亦即验证了该算法的可行性;结构面最小强度震动退化系数随动力激励时程变化近似呈负指数函数形式逐渐衰减,且当结构面初始黏聚力(内摩擦角)越大、而坡角(层面倾角)或动荷载幅值(频率)越小时,地震历时过程中边坡最小动力稳定性系数越大,此时边坡最终动力稳定性相对越强。     

Ranking the rock slope instability potential using the Interaction Matrix (IM) technique; a case study in Iran

All the conventional techniques for the analysis of slope stability ranging from simple kinematic analysis using stereonets, to the various widely used limit equilibrium methods, to sophisticated numerical methods belong to a category that are generally known as the analytic approaches and thus are only able to consider a limited number of affecting factors and then solve the problem in details. In contrast, the systems approaches not only can examine the problem in its totality with a complete list of the components, but also can take the interactions between the factors into account. This paper presents a complete application of a well-known systems technique named the Interaction Matrix (IM) in ranking the instability potential of rock slopes of the Khosh-Yeylagh Main Road, Iran as the case study of the research. For this purpose, 15 stations have been selected and a relatively comprehensive database containing the fieldwork information has been constructed. Following the IM technique, the most important factors relating to the general environment and to the rock mass characteristics have been considered. Their reciprocal causes and effects have been analyzed in order to weight each parameter according to its degree of interactivity in the system. Then, the slope instability index has been calculated which refers to the inherent potential instability of each slope of the examined region. The final instability ranking has been presented for the investigated slopes in Khosh-Yeylagh Main Road based on a simple classification. The main aim of the study is to extend the use of systems approach and specifically the IM technique in slope stability analysis. Also, this research shows the importance of consideration of an approximately complete set of key parameters affecting the stability of rock slopes.     

交通荷载作用下边坡振动响应特性分析

通过对316国道土质边坡及岩质边坡进行振动响应测试,研究交通荷载引起土质及岩质边坡振动加速度大小及其空间变化特征,同时利用FFT方法对振动信号进行频谱分析,得到岩质及土质边坡的振动响应频谱特性。测试及分析结果表明,振动波传播过程中携带了反映介质固有特性的信息,岩质及土质边坡对交通荷载的响应均较为敏感,相同荷载在土质边坡引起的振动加速度及振动幅值大于岩质边坡,其中土质边坡沿坡由下向上振动响应有减弱的趋势,且振动在短距离内衰减较快,而岩质边坡振动响应在短距离内衰减较慢;主频随着振动波的衰减有向低频移动的趋势。测试为分析振动传播途径和研究振动对边坡稳定性的影响提供了宝贵资料,对多因素引起的边坡稳定性评价有重要的实际意义。     

Coupling of two methods,waveform superposition and numerical,to model blast vibration effect on slope stability in jointed rock masses

Drilling and blasting is a major technology in mining since it is necessary for the initial breakage of rock masses in mining. Only a fraction of the explosive energy is efficiently consumed in the actual breakage and displacement of the rock mass, and the rest of the energy is spent in undesirable effects, such as ground vibrations. The prediction of induced ground vibrations across a fractured rock mass is of great concern to rock engineers in assessing the stability of rock slopes in open pit mines. The waveform superposition method was used in the Gol-E-Gohar iron mine to simulate the production blast seismograms based upon the single-hole shot vibration measurements carried out at a distance of 39 m from the blast. The simulated production blast seismograms were then used as input to predict particle velocity time histories of blast vibrations in the mine wall using the universal distinct element code (UDEC). Simulated time histories of particle velocity showed a good agreement with the measured production blast time histories. Displacements and peak particle velocities were determined at various points of the engineered slope. The maximum displacement at the crest of the nearest bench in the X and Y directions was 26 mm, which is acceptable in regard to open pit slope stability.     

露天煤矿冻结岩土边坡介质特征与稳定性分析

为了科学评价冻岩露天矿边坡稳定性,并采用有效措施保证冻岩边坡工程的安全建设和运营,分析了岩石在不同温度条件下多个物理力学参数的变化规律,结果表明,冻结态使岩石的强度得到一定的提高,而冻融循环使岩石的强度产生一定的削弱。由于岩体具有介质和结构的双重属性,冻融循环作用对岩体的介质和结构面损伤均较显著,可以通过改进的Hoek-Brown岩体强度准则分析冻融环境中的岩体强度。基于木里聚乎更矿区冻岩露天煤矿边坡的调查分析,总结归纳了该区冻岩边坡的破坏现象和类型,在冻融循环作用下冻岩边坡的破坏模式基本为浅表部的渐进式破坏。      

岩质边坡滑动-倾倒组合破坏模式稳定性分析

在岩质边坡滑动-倾倒组合破坏地质力学模型的基础上,采用改进的传递系数法,提出了岩质边坡滑动-倾倒组合破坏的解析分析方法,并对初始下滑推力及岩块底部的凝聚力进行敏感性分析。与传递系数法相似,将边坡体几何力学参数及潜在倾倒岩块编号作为变量,使得每个倾倒岩块的稳定性分析具有统一的表达式,并易于采用Microsoft excel进行程序化分析。分析结果表明：岩块底面的凝聚力对下部潜在倾倒区域的破坏模式影响较大,随着岩块底面凝聚力的增加,潜在倾倒区域发生倾倒破坏的块体呈逐渐增加的趋势,而发生滑动破坏的块体则明显较少,岩块底面倾角对坡体整体稳定性影响较大;随着岩块底面倾角的增大,整个坡体的稳定性逐渐降低。     

弹粘塑性块体单元法在龙滩水电站右坝肩边坡稳定分析中的应用

介绍了三维弹粘塑性块体单元法的基本原理。该方法假定岩石块体为刚体,只考虑结构面的变形和强度特性。在建立块体系统的平衡方程、结构面的变形与块体位移的几何相容方程以及结构面上的弹粘塑性本构方程的基础上,出块体系统位移与稳定的基本方程。针对龙滩水电站右坝肩边坡地质条件复杂,块体稳定问题较为突出的情况,采用块体单元法计算了边坡中典型结构面切割形成的特定块体在不同工况下的强度储备安全系数,并针对结构面的几何参数和力学参数等重要影响因素进行了敏感性分析,为工程设计提供了依据。应用表明,作为一种新型的水工结构数值方法,块体单元法应用于复杂地质条件下的岩石高边坡的稳定和变形分析具有准确、适用和简便的特点。     

岩体弹粘塑性显式波动有限元分析

真实反映地震动传播特性的分析方法是准确描述岩体地震反应的基础。基于显式波动有限元,采用能够考虑应变率影响的弹粘塑性本构模型,提出了一种用于分析岩体地震反应的新方法,编制了相应的计算程序。以均质岩石边坡为例,计算了EL-CENTRO波输入下边坡的位移和应力反应,并将计算结果与采用粘弹性本构模型的结果进行了比较,初步验证了程序的可靠性。计算结果表明,所提出的新方法能够较合理地计算出地震作用下边坡的永久位移和残余应力。      

土石混合体边坡细观特征对滑面形成影响研究

土石混合体是由软弱的土颗粒与刚度较大、强度较高的块石混合而成,因此土石混合体边坡失稳时,其滑动面受块石-土形成的细观结构特征影响,导致边坡稳定性分析存在诸多困难。本文基于一典型的土石混合体边坡,建立颗粒离散元数值模型,通过室内试验标定土体细观参数,结合强度折减法分析土石混合体边坡与纯土体边坡破坏模式及滑面形态的差别。结果表明:块石的存在使得土石混合体边坡的接触力链分布极不均匀,块石的存在使接触力链形成闭环,增大了滑动面积,对边坡有加固作用;土石混合体边坡的滑面发展趋势总倾向于穿过块石间的缝隙,滑面的发展与块石分布状况相关联;当块石含量达到20%以上时,边坡稳定性显著提高;块石含量达到30%~50%时,滑坡以局部块体运动为主,无法形成连续的滑动面。研究成果可为土石混合体边坡的变形破坏机理分析提供依据与参考。     

用三维激光成像技术调查高陡边坡岩体结构

论文针对“罗盘 皮尺”传统模式调查高陡边坡岩体结构中的缺点,提出了三维激光成像技术调查高陡边坡岩体结构的新方法。利用三维激光成像技术可获得完全实景的数字模型,并在该数字模型上可直接量取点、线、面和三维实体空间坐标,从而进行结构面产状、迹长与连通率、间距等岩体结构特征参数计算和地质剖面切图。最后,以营盘山陡崖边坡为例,详细阐述了三维激光成像技术调查高陡边坡岩体结构特征参数方法及过程。结果表明,利用三维激光成像技术所得的结构面产状、间距等岩体结构特征参数要优于传统的“罗盘 皮尺”量测结果。因此,三维激光成像技术的引入,必将引发岩体结构特征参数测试技术革新性的发展。     

An Experimental and Theoretical Approach on the Modeling of Sliding Response of Rock Wedges under Dynamic Loading

The stability of rock slopes under dynamic loading in mining and civil engineering depends upon the slope geometry, mechanical properties of rock mass and discontinuities, and the characteristics of dynamic loads with time. The wedge failure is one of the common forms of slope failures. The authors presented some stability conditions for rock wedges under dynamic loading and they confirmed their validity through the laboratory experimental studies in a previous paper in 2000, which is often quoted by others to validate their softwares, including some commercial software. In this study, the authors investigate the sliding responses of rock wedges under dynamic loads rather than the initiation of wedge sliding. First, some laboratory model tests are described. On the basis of these model tests on rock wedges, the theoretical model proposed previously is extended to compute the sliding responses of rock wedges in time domain. The proposed theoretical model is applied to simulate the sliding responses of rock wedge model tests and its validity is discussed. In the final part, the method proposed is applied to actual wedge failures observed in 1995 Dinar earthquake and 2005 Pakistan–Kashmir earthquake, and the results are discussed.     

高陡边坡岩体结构信息无人机识别与离散元数值模拟

岩体结构特征的准确表征对边坡稳定性评价具有重要影响。由于高陡边坡岩体结构的人工编录工作开展困难,结构几何信息往往获取不全面,导致边坡数值模型构建往往不理想。以江西德兴银山铜矿露天边坡为工程背景,采用无人机与运动恢复结构法(SfM)获取边坡岩体点云模型。基于点云数据建立结构面识别和解译算法,自动获取结构面产状、迹长、间距等几何信息。对比人工测量结果,无人机测量与结构面识别能够获取更符合实际的坡面与岩体结构模型。采用非均匀有理B样条(NURBS)曲面重构和“Rhino-Griddle-3DEC”联合建模方法,结合岩体结构统计模型构建离散裂隙网络DFN能够快速建立三维离散元数值模型,从而获得更好的数值模拟计算结果,满足岩质高边坡稳定性评价的需要。     

Study on Three-dimensional Visualization for Rock Structure

The visualization of rock structure is a very useful and important technique in many aspects in geological and geotechnical engineering such as investigating and evaluating the stability of a high rock slope. The conventional method used to visualize rock structure is limited to plotting the orientation of individual discontinuities by using the Schmidt stereographic net. The present paper shows a new technique to visualize the three-dimensional structure of rock masses. The fitting function for three-dimensional rock structure was established based on data gathered from field survey. Two fitting methods by which the discontinuous points gathered from a plane and discrete points from field survey were fitted respectively are suggested. The technique to visualize the three-dimensional structure of rock masses includes many aspects such as projection transformation, blanking and mutual cutting, are investigated. Based on the visualizing technique, the rock structure at the site of Xilupdu dam which is being built in Southwest of China was investigated.     

A multidisciplinary approach for the investigation of a rock spreading on an urban slope

Landslides are very complex processes controlled by multiple factors. The knowledge and characterization of these factors is essential for a comprehensive understanding of the mechanisms and kinematics of the instabilities and for an efficient design of corrective measures. The aim of this work is to combine traditional geological and geotechnical techniques with geophysical, remote sensing and forensic techniques for obtaining a whole picture of an active lateral spreading affecting the Finestrat municipality in Alicante, SE Spain. Geomorphological, geotechnical and geophysical techniques (i.e. ground penetrating radar and refraction seismic) have provided essential information about the geometry, structure and petro-physical properties of the slope. A Terrestrial Laser Scanner was used for recognizing the most important sets of discontinuities affecting the rock mass and to evaluate the activity of the landslide slope. Complementarily, a forensic analysis of the building damage completed the available datasets, yielding very useful kinematic information of the landslide. Finally, a sensitivity analysis of the stability of the rock slope has been performed considering both block toppling and block sliding models. Therefore, the multisource analysis performed in this work has allowed the identification and characterization of a complex lateral spreading, highlighting its effectiveness for a comprehensive understanding of this type of landslide.     

重庆拉法基搅拌站岩质边坡稳定性分析

本文研究重庆拉法基长寿智深混泥土搅拌站岩质边坡稳定问题。针对该边坡所处的地形地貌、地层岩性、地质构造和气象水文条件,分析了影响岩质边坡稳定性的主要因素,归纳了该边坡可能的主要工况类型。在此基础上,采用块体极限平衡法对边坡进行了稳定性分析,并最终提出了以下综合治理措施：“表里排水”、“削坡减载”、“坡面防护”、“锚杆格构”以及“重力式挡墙支挡”。这些措施在后期施工中得到了应用,并取得了不错的效果,可为类似工程问题的分析评价提供借鉴。     

Use of backpropagation neural network for landslide monitoring: a case study in the higher Himalaya

Static and dynamic rock slope stability analyses were performed using a numerical discontinuum modelling technique for a 700-m high rock slope in western Norway. The rock slope has been investigated by the Geological Survey of Norway (NGU), which has been carrying out rock slide studies for the county Møre and Romsdal in western Norway. The purpose of numerical modelling was to estimate the volume of the rock mass that could potentially slide under static and dynamic forces. This estimation was required to assess the run-up heights (tsunami) in a fjord that could potentially be caused by the rockslide. Three cases have been simulated for predicting the behaviour of the rock slope. First, an initial static loading is applied in the numerical model to simulate the prevailing rock mass conditions at the site. Second, saturated and weathered joint conditions are modelled by reducing the residual friction angle along the discontinuities of the rock mass. In doing so, the model simulates the effect of degradation of discontinuities in the rock slope. Third, a dynamic loading, based on peak ground accelerations expected in the area, is applied to simulate dynamic earthquake conditions.

These numerical studies have provided some useful insights into the deformation mechanisms in the rock slope. Both sliding and rotation of blocks start to occur once the residual friction angle along the discontinuities is reduced and when the region is shaken by a strong earthquake. The results indicate that, due to variations in the inclination of discontinuities, the entire slope does not become unstable and that down-slope sliding and rotation of blocks occur mainly on the top layers of the slope. Within the range of parameter values considered for this study, it is unlikely that the whole rock slope can be destabilised. The study provides an illustration of how the geo-mechanical properties of a rock mass can be integrated in a discontinuum rock slope model, which is used for predicting the behaviour of the slope under existing environmental and earthquake conditions. This model has helped not only to better understand the dynamics of the rockslide but also to estimate the potential rock volume that can become unstable when subjected to static and dynamic loads.