危岩体稳定性评价及工程实例分析

以宜宾市宜宾县喜捷镇边坡危岩体作为研究对象,通过分析危岩体的状况,对危岩体的稳定性进行了赤平投影分析,结果表明：危岩块体底部存在与坡面近反向的缓倾结构面,该危岩块体在暴雨、地震或其它异常地质营力的诱发下,将可能沿着其与母岩的接触面发生滑塌;可采用地锚加钻孔灌浆加固,防石墙、栏石板支撑,以及清除余石的综合治理方案来防止危岩体滑塌.     

Constitutive Laws of the Underground Opening Collapse due to Dynamic Load

The constitutive laws of the collapse of underground openings in a rock massif were investigated based on the results of laboratory and field experiments,and computations using analytical and numerical models.It is shown that the principal mechanism of failure of underground openings over important for practice peak particle velocity amplitude range of 1 to 10 m/s is the roof and wall breakage due to the fall of key blocks.Over this load range the material crushing is of considerably less importance.The geometry of discontinuities influences mainly the stability of key blocks.Further caving depends weakly on block structure of near-tunnel zone.The mean volume of fall material is a rather stable quantity for rock massifs of different structures.Lower tunnel stability in the zones of high fracturing is caused by a higher probability of the presence of the unstable key blocks and the decrease of strength characteristics of fractured bounding blocks.The decrease of average block size is a less important accompanying factor.     

Constitutive Laws of the Underground Opening Collapse due to Dynamic Load

The constitutive laws of the collapse of underground openings in a rock massif were in-vestigated based on the results of laboratory and field experiments, and computations using ana-lytical and numerical models. It is shown that the principal mechanism of failure of underground openings over important for practice peak particle velocity amplitude range of 1 to 10 m/s is the roof and wall breakage due to the fall of key blocks. Over this load range the material crushing is of considerably less importance. The geometry of discontinuities influences mainly the stability of key blocks. Further caving depends weakly on block structure of near-tunnel zone. The mean volume of fall material is a rather stable quantity for rock massifs of different structures. Lower tunnel sta-bility in the zones of high fracturing is caused by a higher probability of the presence of the unsta-ble key blocks and the decrease of strength characteristics of fractured bounding blocks. The de-crease of average block size is a less important accompanying factor.     

Dynamic instability of tunnel in blocky rock mass

The displacements and geometry of the rock blocks and the properties of the rock struc-ture play an important role in the stability of tunnels.Based on the key block model,the dynamic instability analysis of underground tunnel subjected to intensive short-time compressional wave was conducted.The instability of the tunnel caused by the spallation and the inertial effect was distin-guished.And the influence of the roof contour curvature of tunnel was also determined.     

路堑岩质边坡稳定性级别研究

路堑岩质边坡具有规模大、数量多、参数获取困难、治理难度大等特点,历来是线路工程中的研究热点.为了解决路堑岩质边坡的稳定评价问题,建立边坡稳定性的模糊综合评价体系,可供同类工程借鉴.根据路堑岩质边坡的特点,以系统全面性、简明科学性、相对独立性及灵活可操作性为原则,选取合理的边坡稳定性评价指标,建立边坡稳定性的模糊综合评价体系,运用层次分析法确定评价指标的权重,建立了路堑岩质边坡的稳定性分级模型.以某国道辅线K57+411～K57+536段边坡为例,运用该模型对其稳定性级别进行了模糊综合评判分级,其结果为不稳定,与规范法的评价结果一致,表明该方法是合理实用的.     

Upper bound solution of supporting pressure for a shallow square tunnel based on the Hoek-Brown failure criterion

To analyze the stability of a shallow square tunnel, a new curved failure mechanism, representing the mechanical characteristics and collapsing form of this type of tunnel, is constructed. Based on the upper bound theorem of limit analysis and the Hoek-Brown nonlinear failure criterion, the supporting pressure derived from the virtual work rate equation is regarded as an objective function to achieve optimal calculation. By employing variational calculation to optimize the objective function, an upper bound solution for the supporting pressure and the collapsing block shape of a shallow square tunnel are obtained. To evaluate the validity of the failure mechanism proposed in this paper, the solutions computed by the curved failure mechanism are compared with the results calculated by the linear multiple blocks failure mechanism when the Hoek-Brown nonlinear failure criterion is converted into the Mohr-Coulomb linear criterion. The influences of rock mass parameters on the supporting pressure and collapsing block shape are discussed.     

基于霍克-布朗准则的深埋隧道塌方机制泛函突变分析

研究目的：分析深埋隧道的塌方机制并推导塌方体形状曲线的解析表达式。创新要点：基于霍克-布朗准则,采用泛函突变理论推导得到了深埋隧道塌方体形状曲线的解析表达式,并据此分析了围岩参数变化对塌方体形状的影响规律。研究方法：通过理论分析建立深埋圆形隧道的解析模型（图1）,采用泛函突变理论推导基于霍克-布朗准则的隧道塌方体形状曲线解析表达式,并研究围岩参数变化对塌方体形状的影响规律（图3和4,表2）。通过与自然拱理论和模型试验结果的对比（图5–7）验证本文解析解的正确性。重要结论：采用泛函突变理论推导了基于霍克-布朗准则的深埋隧道塌方体形状曲线解析表达式。该解析表达式简洁直观,不仅可以预测无支护条件下隧道的塌落体尺寸,还可以估算塌落围岩作用于衬砌上的荷载。     

Adolescent boys' and girls' block constructions differ in structural balance: A block-building characteristic related to math achievement

Two studies were conducted on block building in adolescents, assessing middle school (Study 1) and high school students (Study 2). Students were asked to build something interesting with blocks. In both samples, the same pattern of gender differences were found; boys built taller structures than girls, and balanced a larger number of blocks on a small base of upright blocks (a new measure developed for this study). Gender differences in the height of structures were fully mediated by this measure of structural balance. These findings suggest that balance elements are key to understanding gender differences in block building. In Study 2, high-school students were given a second task, requiring them to apply structural balance principles (only four upright blocks were provided on which to build), and instructing them to build a tall, complex, well-balanced structure. Gender differences again were found, suggesting that gender differences in block building may be skill-based as well as stylistic. A separate question was whether block-building characteristics at this age have any relevance to math achievement. In both studies, the measure of structural balance was the only block-building characteristic that predicted math achievement. Additional research is needed to understand the cognitive underpinnings of this new spatial measure, how malleable it is, and its further practical significance for adolescent learners.     

Analysis of Covariance and Randomized Block Design with Heterogeneous Slopes

The authors compared the Type I error rate and the power to detect differences in slopes and additive treatment effects of analysis of covariance (ANCOVA) and randomized block (RB) designs with a Monte Carlo simulation. For testing differences in slopes, 3 methods were compared: the test of slopes from ANCOVA, the omnibus Block × Treatment interaction, and the linear component of the Block × Treatment interaction of RB. In the test for adjusted means, 2 variations of both ANCOVA and RB were used. The power of the omnibus test of the interaction decreased dramatically as the number of blocks used increased and was always considerably smaller than the specific test of differences in slopes found in ANCOVA. Tests for means when there were concomitant differences in slopes showed that only ANCOVA uniformly controlled Type I error under all configurations of design variables. The most powerful option in almost all simulations for tests of both slopes and means was ANCOVA.     

地质超前预报系统在栋梁坡隧道施工中的应用

基于地震反射波法超前预测系统的原理及主要技术手段,以栋梁坡隧道工程为实例,针对隧道复杂的地质条件,施工过程中将超前地质预报和地质素描调查相结合,先对隧道全段范围内地形、地层岩性等进行全面核查,然后结合核查结果运用地震反射波法预报掌子面前方的节理裂隙发育情况,围岩完整性等地质信息。开挖后验证情况与预测结果基本一致,为后续预防突水塌方等隧道地质灾害事故的发生提供数据支撑,有效保证栋梁坡隧道的施工安全。     

广西邕宁梯级工程岩石库岸稳定分析

库岸稳定问题是水利工程中十分重要和常见的工程问题。组成岸坡岩土体可分为岩石岸坡和土质岸坡。本文结合南宁市邕宁梯级工程,对影响岩石岸坡的稳定因素进行探讨,并通过"岩土软件GEO5"进行计算,计算结果表明:坡外河水位及岩体裂隙水位的变化对岸坡稳定影响显著,坡外河水位对边坡稳定有利,裂隙水对边坡稳定不利。     

三维粘弹塑性有限元凝聚法研究复杂坝基开挖

为探讨坝基开挖对建基面和坝肩稳定的影响 ,建立粘弹塑性模型 ,用有限元凝聚法对坝基开挖稳定问题进行分析计算 ,研究了建基面及软弱结构面与时间因素有关的位移、应力、屈服破坏的动态过程 .结果表明 ,采用的理论和计算方法合理 ,计算程序具有精度高 ,收敛速度快等特点 ,展示了良好的应用前景     

松软煤岩大直径长钻孔失稳控制方法研究

针对深部钻孔软弱围岩层的岩石力学性质,通过软件对巷道顶板、底板等不同层位大直径钻孔的岩石力学特征进行了弹塑性状态下大直径钻孔二次应力分布特征、弹塑性区的变化规律以及钻孔径向位移的变化趋势数值模拟,并建立了数值模型,得出复杂条件下深部煤岩弱结构大直径长钻孔失稳的力学特性,给出了解决大直径钻孔稳定的关键技术和固孔工艺方法。     

How to repair the Hill cipher

INTRODUCTION Owing to the advance in network technology, information security is an increasingly important problem. Popular application of multimedia tech- nology and increasingly transmission ability of net- work gradually leads us to acquire information di- rectly and clearly through images. Hence, data secu- rity has become a critical and imperative issue. Hill cipher is a block cipher that has several advantages such as disguising letter frequencies of the plaintext, its simplicity be…     

The fracture network model of Shen 229 block buried hill： A case study from Liaohe Basin, China

INTRODUCTION Several fields in Liaohe Basin are host to frac- tured hydrocarbon oil reservoir, fractures are consid- ered to influence productivity significantly in these reservoirs, which not only form a large part of the overall porosity, but also are responsible for the po- tential reservoir volume. More importantly, the frac- ture system facilitates permeability and flow. Ce- mented and closed fractures act as barriers to flow, whereas open fractures intersected by the wellbore may in…     

基于差异演化的多聚焦图像融合算法

多聚焦图像融合就是综合和处理多个源图像的信息,来获取对同一场景或物体的更为准确、更为全面、更为可靠的图像描述．对于可见光成像系统而言,特别是含有长焦距的光学镜头,对景深有一定的限制．因此,将场景中的所有物体都成像清晰是很难的,这个问题采用多聚焦图像融合技术可以很好解决．通过提出一种基于差异演化的多聚焦图像融合算法,首先将源图像进行分块,然后用清晰度评价函数比较对应图像块的清晰度,选择清晰度高的作为清晰图像块,最终重构融合图像．该方法的积极意义在于,优化后的图像块比没被优化的使用效果更佳．实验结果表明,从定量和视觉两方面评价,都明显优于遗传算法和其他传统的图像融合方法．     

Coupled Numerical Analysis of the Stability Behaviour of Unsaturated Soil Slopes Under Rainfall Conditions

Thebasicstressvariablesintheconstitutivemodelde velopedbyAlonsoetal[5] aresoilnetstressandsoilmatricsuctions ,whicharedefinedby　　　σ″ =σ -ua (1)　　　s=ua-uw (2 )whereσisthetotalstress,uwistheporewaterpressureanduaistheporeairpressure .　　Thenetmeanstresspanddeviatoricstressqarede finedas　　　p =σ1+2σ33-ua (3)　　　q =σ1-σ3(4 )　　Asgenerallyregarded ,thesoilsuctioniscomposedoftwoparts ,matricsuctionandosmosissuction .TheosmosissuctionisneglectedoriginallyinAlonsoetal′smodelandhe…     

Efficient Hierarchical Structure of Wavelet-Based Compression for Large Volume Data Sets

With the increasing resolution of medical CTscanners, datasets of 10—100 gigabyte sizes are get-ting more and more common[1]. Due to their large si-zes, the transmission between data server and brows-ing clients over low-bandwidth networks and the dis-play of these data sets are time-consuming. There-fore, multiresolution models are developed, so thatthe data can be visualized incrementally as they arrive(progressive refinement). Wavelets are a natural can-didate for such a multiresolution a…     

基于FLAC3D的加筋土填方边坡稳定性分析

以陕西某山区高填方工程为背景,运用强度折减法和关联流动法则,对该场地某超高加筋土边坡夯后的水平位移、竖直位移、最大主应力、最小主应力等力学行为进行数值分析,研究了土工格栅对加筋高填方边坡稳定性的影响,并对土工格栅垂直间距参数设计进行比选和优化。结果表明:无筋边坡的潜在滑移面比加筋边坡更靠近坡面,加筋不仅能提高边坡安全系数,而且能降低边坡的最大剪应变与最大位移;筋材铺设存在最佳间距区域,合理的铺设间距能够有效提高加筋高边坡的稳定性。     

基于小波变换的纹理合成算法研究

基于样图的纹理合成基本思想是根据给定的小区域的纹理样本,拼合生成任意大小的纹理图像并且在视觉上与样本是相似而连续的。通过对基于样图的纹理合成算法进行研究,在待合成纹理块的搜索策略上,提出优先搜索前一个已合成纹理块在样图中的位置附近,快速定位下一个用于合成的纹理块。在纹理块的匹配策略中引入小波变换,结合小波变换后的小波系数和小泼变换后的低频域图像进行块的重叠区域匹配,最后使用最小路径法将待合成纹理块缝合到输出图像中。充分考虑了样图的结构信息并提高了合成速度,获得了较好的纹理合成效果。