裂隙化岩体中圆形断面调压井围岩稳定性分析

块体理论是适用于裂隙化岩体变形失稳分析的有效方法。运用块体理论赤平投影法研究某水电站超大型调压井围岩随机块体的稳定性,将圆形断面调压井开挖临空面抽象简化为八个方位的边墙加以研究,分析了井周各部位可能的关键块体及其运动形式,计算了关键块体的净滑力。分析结果对工程施工具有可靠的现实指导作用,为锚固设计和永久衬砌设计提供了依据,可供类似工程参考。     

Rock Analysis Using Inductively Coupled Plasma Mass Spectrometry: a Review

The applications of inductively coupled plasma -mass spectrometry (ICP-MS) to geoanalysis are reviewed. This technique offers the ability to determine elemental abundances and isotope ratios; it has proven to be sensitive, precise and accurate, and represents a significant advance in instrumentation suitable for rock analysis. This review deals principally with the application of ICP-MS to elemental analysis. Literature citations are complete as of December 31, 1987; particular attention has been paid to data reported for certified reference materials. Although most current ICP-MS analysis employs conventional nebulization of solution samples, there is considerable effort being made to develop viable alternative sample introduction schemes that can be applied to rock analysis. The lack of adequately defined certified reference rock materials is apparent for ICP-MS and other techniques that are capable of routine determinations in the ng/g (ppb) range.     

Numerical Analysis of Blast-Induced Stress Waves in a Rock Mass with Anisotropic Continuum Damage Models Part 2: Stochastic Approach

Summary This paper reports the second part of the study carried out by the authors on the underground explosion-induced stress wave propagation and damage in a rock mass. In the accompanying paper reporting the first part of the study, equivalent material properties were used to model the effects of existing cracks and joints in the rock mass. The rock mass and its properties were treated as deterministic. In this paper, existing random cracks and joints are modeled as statistical initial damage of the rock mass. In numerical calculation, an anisotropic continuum damage model including both the statistical anisotropic initial damage and cumulative damage dependent on principal tensile strain and stochastic critical tensile strain is suggested to model rock mass behavior under explosion loads. The statistical estimation of stress wave propagation in the rock mass due to underground explosion is evaluated by Rosenblueth's point estimate method. The suggested models and statistical solution process are also programmed and linked to Autodyn3D as its user's subroutines. Numerical results are compared with the field test data and those presented in the accompanying paper obtained with equivalent material property approach.     

Three-Dimensional Modeling of Mass Transfer in Porous Media Using the Mixed Hybrid Finite Elements and the Random-Walk Methods

A three-dimensional (3D) mass transport numerical model is presented. The code is based on a particle tracking technique: the random-walk method, which is based on the analogy between the advection–dispersion equation and the Fokker–Planck equation. The velocity field is calculated by the mixed hybrid finite element formulation of the flow equation. A new efficient method is developed to handle the dissimilarity between Fokker–Planck equation and advection–dispersion equation to avoid accumulation of particles in low dispersive regions. A comparison made on a layered aquifer example between this method and other algorithms commonly used, shows the efficiency of the new method. The code is validated by a simulation of a 3D tracer transport experiment performed on a laboratory model. It represents a heterogeneous aquifer of about 6-m length, 1-m width, and 1-m depth. The porous medium is made of three different sorts of sand. Sodium chloride is used as a tracer. Comparisons between simulated and measured values, with and without the presented method, also proves the accuracy of the new algorithm.     

基于包络线消除法的岩石光谱对应分析

岩石光谱特征是岩性识别的物理基础。选取常见的10种岩石类型15种岩石样品的光谱数据,对其进行均值、重采样、平滑、水汽吸收波段拟值等预处理,以消除岩石光谱噪声,然后通过包络线消除法,获得了岩石光谱特征参数,发现云母板岩（风化面）吸收特征最为明显;对包络线消除处理后的光谱数据进行对应分析,提取出R型主因子载荷,得到第一主因子轴代表主要的阳离子、阴离子诊断波段和水分子吸收波段,第二主因子轴代表少数阳离子的特征波段,获得与岩石相关的特征波段为385~525 nm、735~1 365 nm、1 435~1 785 nm、1 890~1 952 nm、1 995~2 310 nm,并找出了主要吸收波段的物理含义。通过对应分析二维图像,将岩石光谱分为4类,从第一类到第四类吸收深度逐渐变浅,吸收面积呈递减趋势,吸收宽度逐渐变窄,吸收峰逐渐增多,Fe²⁺和Fe³⁺吸收峰增多,铁化、泥化蚀变现象更明显。用聚类分析法对分类结果进行验证发现,分类结果有较好的对应性。从而为岩石和成像光谱图像数据精细分类提供参考依据,实现了对岩石高光谱海量数据的有效提取,进而为遥感矿产预测和找矿提供依据。     

Reinforcing a Dangerous Rock Mass Using the Flexible Network Method

Because the main failure type of a dangerous rock mass is collapse, the treatment of such a mass should focus on controlling collapse failure. When treating dangerous rock masses, disturbing the mass （e. g. by blasting） needs to be avoided, as this new damage could cause collapse. So the self-bearing capacity of the mountain mass must be used to treat the dangerous rock mass. This article is based on a practical example of the control of a dangerous rock mass at Banyan Mountain, Huangshi, Hubei Province. On the basis of an analysis of damage mechanism and the stability of the dangerous rock mass, a flexible network reinforcement method was designed to prevent the collapse of the rock mass. The deformations of section Ⅱ w of the dangerous rock mass before and after the flexible network reinforcement were calculated using the two-dimensional finite element method. The results show that the maximum deformation reduced by 55 % after the application of the flexible network reinforcement, from 45.99 to 20.75 ram, which demonstrates that the flexible network method is effective, and can provide some scientific basis for the treatment of dangerous rock masses.     

基于三维激光点云技术的岩体结构面智能解译

准确、高效、全面获取岩体结构面信息,对岩体的稳定性分析有着重要的意义.采用三维激光扫描设备进行岩体数据采集,基于岩体点云模型提出了结构面自动识别方法.通过对Ransac算法进行改进,引入了新的采样方法和评分准则,大大提升了Ransac算法的计算效率和提取精度,使之更好地适应粗糙不平的岩体点云数据;基于改进的Graham...     

Numerical Analysis of Blast-Induced Stress Waves in a Rock Mass with Anisotropic Continuum Damage Models Part 1: Equivalent Material Property Approach

Summary This paper uses the concept of anisotropic damage mechanics to analyze dynamic responses of a granite site under blasting loads. An anisotropic continuum damage model is suggested to model rock mass behavior under blasting loads. The effects of existing cracks and joints in the rock mass are considered by using equivalent rock material properties obtained from both field and laboratory test data. The anisotropic damage accumulations are simulated by continuous degradation of equivalent material stiffness and strength during loading process and are calculated using the exponential function with respect to the principal tensile strain in three directions. The suggested models are programmed and linked to an available computer program Autodyn3D through its user's subroutine capability. Stress wave propagation and damage zone in the rock mass induced by underground explosions are simulated. Numerical results of damaged area, peak particle velocity and acceleration attenuation as well as acceleration time histories and Fourier spectra are compared with those from independent field tests.     

乌东德坝区拱座岩体三维裂隙连通率特征

裂隙连通率是进行岩体稳定性评价不可或缺的参数,合理确定三维裂隙连通率的大小一直是岩体力学中的难题之一.结合金沙江乌东德水电站工程,采用投影法对乌东德坝区850m高程的拱座岩体进行了三维连通率研究.根据研究区域的工程地质条件,确定了拱座岩体的潜在滑动边界;采用逆建模方法建立拱座岩体的裂隙网络模型;在裂隙网络模型中设置不同大小、不同位置和不同方位的投影面进行三维连通率求解,探讨三维连通率的尺寸效应、分布特征和空间变化规律.研究结果表明:侧滑面连通率尺寸效应显著而底滑面连通率尺寸效应不明显;侧滑面连通率近似呈正态分布,左岸侧滑面连通率均值为3.9%,右岸侧滑面连通率均值为8.1%;侧滑面连通率随空间方位产生明显变化,投影面倾角越大,侧滑面连通率越小.这为乌东德坝区拱座岩体的稳定性评价提供了重要的参数依据.     

软岩立井井壁与流变岩体相互作用的实验分析

利用流变介质模型，分析软岩立并并壁与粘弹塑性围岩的相互作用。根据现场实测结果及围岩压力与时间的关系，得到围岩应力、位移随时间的变化规律和粘塑性区的扩展规律。     

Anisotropic Deformation of a Circular Tunnel Excavated in a Rock Mass Containing Sets of Ubiquitous Joints: Theory Analysis and Numerical Modeling

Determining anisotropic deformation surrounding underground excavations for tunnels is an intuitional task that involves many difficulties due to the inherent anisotropies in the strength and deformability of natural rocks. This study investigates joint-induced anisotropic deformation surrounding a tunnel via a numerical simulation that accounts for the mechanical behavior of intact rock, the orientations of joint sets, and the mechanical behavior of joint planes; this numerical simulation can model the complete stress–strain relationship with anisotropic rock mass characteristics. Simulation results demonstrate that the well-known excavation-induced stress variation–decrease in the radial component and increase in the tangential component–decrease shear strength and increase shear stress for the joint plane tangential to the tunnel wall, resulting in joint sliding failure and considerable shear deformation. This joint sliding failure and significant shear deformation account for the joint-induced anisotropic deformation surrounding a tunnel. When a rock mass has two joint sets with unfavorable joint orientations, the area with joint sliding failure can deteriorate mutually, resulting in large anisotropic deformation. Additionally, for a rock mass containing three joint sets with well-distributed orientations, joint sliding in various joint sets and associated stress variations can counter balance each other, resulting in less anisotropic deformation than those of rock masses containing one or two joint sets.     

裂隙岩体边坡稳定性分析方法

岩石边坡，尤其是裂隙岩体边坡稳定性分析应考虑岩体中结构面的产状、性质和发育程度。对随机发育的岩体结构面，赤平极射投影是确定优势结构面及分析边坡潜在破坏模式的基础。以某电厂高100m以上岩石高边坡为例，介绍了采用赤平投影图解法及极限平衡法，进行岩体边坡稳定性分析的方法。     

Slope Stability Problems and Back Analysis in Heavily Jointed Rock Mass: A Case Study from Manisa, Turkey

This paper presents a case study regarding slope stability problems and the remedial slope stabilization work executed during the construction of two reinforced concrete water storage tanks on a steep hill in Manisa, Turkey. Water storage tanks of different capacities were planned to be constructed, one under the other, on closely jointed and deformed shale and sandstone units. The tank on the upper elevation was constructed first and an approximately 20-m cut slope with two benches was excavated in front of this upper tank before the construction of the lower tank. The cut slope failed after a week and the failure threatened the stability of the upper water tank. In addition to re-sloping, a 15.6-m deep contiguous retaining pile wall without anchoring was built to support both the cut slope and the upper tank. Despite the construction of a retaining pile wall, a maximum of 10 mm of displacement was observed by inclinometer measurements due to the re-failure of the slope on the existing slip surface. Permanent stability was achieved after the placement of a granular fill buttress on the slope. Back analysis based on the non-linear (Hoek–Brown) failure criterion indicated that the geological strength index (GSI) value of the slope-forming material is around 21 and is compatible with the in situ-determined GSI value (24). The calculated normal–shear stress plots are also consistent with the Hoek–Brown failure envelope of the rock mass, indicating that the location of the sliding surface, GSI value estimated by back analysis, and the rock mass parameters are well defined. The long-term stability analysis illustrates a safe slope design after the placement of a permanent toe buttress.     

Fast Upscaling of the Hydraulic Conductivity of Three-Dimensional Fractured Porous Rock for Reservoir Modeling

Mathematical Geosciences - A fast upscaling procedure for determining the equivalent hydraulic conductivity of a three-dimensional fractured rock is presented in this paper. A modified...     

Implementation of a Flaw Model to the Fracturing Around a Vertical Shaft

Summary This paper investigates whether a micromechanical model developed to investigate the relation between the basic failure processes at grain-scale and the macroscopic failure pattern can be applied to model the fracturing around large-scale excavations. The simulated fracture pattern around a vertical shaft is compared to the fracturing around a shaft at a depth of 3400 m. The simulations suggest that wedge-shaped zones, called dog-ears, are formed by a progressive splitting-like failure of the rock. The fractures forming these slabs nucleate in the zones subjected to the highest compressive stresses. Both shear and tensile mechanisms are responsible for the fracturing. The dog-ears deepen and widen as spalling continues. Received June 5, 2001; accepted September 24, 2002; Published online January 21, 2003 Acknowledgements The simulations presented in this paper form part of the PhD study of B. Van de Steen at the KULeuven. The authors wish to thank the sponsors of the Deepmine project for the permission to use the information pertaining to the fracturing around the South shaft at Western Deep Levels. Authors' address: André Vervoort, Katholieke Universiteit Leuven, Faculty of Engineering, Department of Civil Engineering, Kasteelpark Arenberg 40, B-3001 Leuven, Belgium; e-mail: andre.vervoort@bwk.kuleuven.ac.be     

地下水封洞库深部岩体结构面连通性研究

地下水封洞库工程是我国正在大力实施的战略石油储备重点工程,研究建库裂隙岩体的连通性是评价水封效果的关键。结合地下水封洞库工程的岩体特征,以钻孔电视成像技术为手段,通过分析影像中结构面位置、地质特征等,建立不同钻孔间结构面连通的条件,并分析了钻孔ZK11和ZK12,ZK12和ZK14的变质分异结构面的几何连通性;以洞库区钻孔地下水位的陡降与施工巷道开挖的相关关系,建立了巷道地下水排泄与钻孔水位下降的水力联系,分析了结构面的水力连通性;通过几何连通和水力连通的综合分析,确定了深部岩体结构面的连通性。研究结果表明,施工巷道开挖引起钻孔地下水位的显著下降,两者存在明显水力联系;变质分异结构面(J)在钻孔ZK12、ZK11和①号施工巷道0+379.424m处满足位置连通、结构面特征连通和水力连通,为连通性结构面;结构面(J′)在钻孔ZK12和ZK14处满足位置连通和结构面特征连通,不满足水力连通,为非连通性结构面。这对地下工程深部岩体结构面连通性的研究具有参考和借鉴价值。     

单纯形法及其在广蓄电站转岩变形反分析中的应用

Surrounding rocks of GPSH ( Guangzhou Pumped Storage Hydroplant) are treated as isotropic medium or orthotropic jointed rocks. Directed back analyses of measured displacements from observation section in access gallery and exhaust gallery of main transformer house are made by simplex acceleration method. A number of mechanical parameters of rock mass and in-situ ground stresses are obtained and compared with measured data.