软弱夹层几何参数对试样力学行为影响颗粒元模拟研究   总被引：2，自引：0，他引：2  

张晓平  吴顺川  张兵  潘文 《工程地质学报》2008,16(4):539-545

基于离散元理论的颗粒元程序,采用颗粒接触连接模型和滑动模型,建立了含软弱夹层试样的颗粒元模型。通过数值模型实验,对不同软弱夹层几何参数试样进行加载模拟,探讨了不同夹层厚度及不同倾角条件下试样的破坏过程和破坏形式,并分析其对试样强度的影响。模拟结果表明,裂隙首先产生于软弱夹层处,随着荷载的增加,再逐渐扩展,呈现渐进性破坏特征;夹层越厚,倾角越大,试样沿软弱夹层呈现较强的滑动特征,如果夹层薄且缓,软弱夹层成为试样破坏的非控制因素;软弱夹层厚度和夹角对试样的峰值强度都有影响,随软弱夹层厚度和夹角的增大,试样的峰值强度降低。  相似文献   

三峡库区巫山县望霞乡廖家坪高陡斜坡失稳机制研究     

黄波林  刘广宁  彭轩明 《华南地质与矿产》2008,(4):49-55

廖家坪高陡斜坡详细勘查结果表明廖家坪坡体上分布有7层软弱层,发育有两组高倾角节理,相互垂直,形成众多危岩体岩柱。上部软弱层为蠕滑层,悬崖壁存在的众多危岩体及岩柱以软弱层为基底。根据平推式滑坡的变形失稳机理分析,计算其起动临界水头高度,认为该斜坡上部坡体平推式滑动的可能性较小。根据工程地质类比法认为由于基础风化压缩,也可造成硬岩拉张,形成次生倾倒破坏;采用离散元分析验证了廖家坪高陡斜坡倾倒破坏演化过程,模拟结果与野外调查的变形破坏现象完全一致,表明该高陡斜坡的变形破坏机制为倾倒失稳模式。这一破坏模式的判定为廖家坪高陡斜坡的稳定性分析和防治提供了重要依据。  相似文献   

Time-dependent stress change during failure of rocks     

V.T. Belikov  A.F. Shestakov 《Russian Geology and Geophysics》2008,49(5):350-356

The energy balance of a solid subject to fracture has been explored using heat and mass transfer equations with regard to the volumetric and superficial components. In the suggested model, brittle fracture of a cracked solid considered as a heterogeneous two-phase medium is described by an equation analogous to the Griffith’s criterion for propagation of a single crack. The derived equation is used, together with estimates of relative change in specific interface area, to study the respective change of free strain energy and pressure in rocks associated with failure.  相似文献   

人工边坡潜在滑动面研究——以广州科学城某人工高边坡为例   总被引：2，自引：2，他引：0  

徐佩华  陈剑平  石丙飞  仲志成 《吉林大学学报(地球科学版)》2008,38(5)

运用强度参数的改变对边坡破坏面形迹影响不明显这一特点,在数值模拟过程中通过改变岩体强度参数,有效地获取潜在滑动面的位置和形态,较好地解决了滑动面搜索的难题。将该法应用于广州科学城某人工高边坡稳定性的研究,在三维数值模拟过程中,将强度参数大幅度折减,计算后获得各剖面的剪应变增量图,从这些图中可获得潜在滑动面。这与人们通常将此类边坡的中风化面作为滑动面存在较大差别。将该滑动面运用极限平衡法进行计算,计算结果显示各剖面的安全系数基本都大于1.2,边坡稳定但仍需要加固处理,与三维数值模拟结果相一致。由此认为用这种分析法确定出的潜在滑动面合理、计算结果可靠,可作为搜索边坡潜在滑动面并计算安全系数的方法之一。  相似文献   

Experimental investigation of the elastic modulus of a fractal system—A model of fractured rocks     

T. L. Chelidze  H. Spetzler  I. C. Getting  Z. A. Avaliani 《Pure and Applied Geophysics》1990,134(1):31-43

The elastic properties of a physical model representing a damaged rock matrix were studied using a square lattice deformed under tensile stress. The elastic modulusM of such a system varies in agreement with percolation theory as|x–x _c | ^f , wherex is the damage parameter andx _c the threshold value of the damage parameter,f3.6. Atxx _c the scale dependence ofM can be expressed asML ^–f/v , whereL is the size of the sample andv the correlation exponent in percolation theory.The experimental results are of interest in assessing elastic properties in earthquake focal zones and fault zones in general.  相似文献   

Peak discharge of a Pleistocene lava-dam outburst flood in Grand Canyon, Arizona, USA   总被引：1，自引：0，他引：1  

Cassandra R. Fenton  Robert H. Webb 《Quaternary Research》2006,65(2):324-335

The failure of a lava dam 165,000 yr ago produced the largest known flood on the Colorado River in Grand Canyon. The Hyaloclastite Dam was up to 366 m high, and geochemical evidence linked this structure to outburst-flood deposits that occurred for 32 km downstream. Using the Hyaloclastite outburst-flood deposits as paleostage indicators, we used dam-failure and unsteady flow modeling to estimate a peak discharge and flow hydrograph. Failure of the Hyaloclastite Dam released a maximum 11 × 10⁹ m³ of water in 31 h. Peak discharges, estimated from uncertainty in channel geometry, dam height, and hydraulic characteristics, ranged from 2.3 to 5.3 × 10⁵ m³ s⁻¹ for the Hyaloclastite outburst flood. This discharge is an order of magnitude greater than the largest known discharge on the Colorado River (1.4 × 10⁴ m³ s⁻¹) and the largest peak discharge resulting from failure of a constructed dam in the USA (6.5 × 10⁴ m³ s⁻¹). Moreover, the Hyaloclastite outburst flood is the oldest documented Quaternary flood and one of the largest to have occurred in the continental USA. The peak discharge for this flood ranks in the top 30 floods (>10⁵ m³ s⁻¹) known worldwide and in the top ten largest floods in North America.  相似文献   

A highlight of environmental and engineering geology in Fargo, North Dakota, USA     

Fred J. Anderson 《Environmental Geology》2006,49(7):1034-1042

Several unfavorable environmental and engineering geologic conditions exist in Fargo, North Dakota. Dominantly, the behavior of smectitic clays within the proglacial Lake Agassiz sediments of the Sherack and Brenna Formations creates subsoil instability beneath engineered structures in the Fargo area and slope instability within cutbank meanders of the Red River of the North. Unfavorable engineering geologic conditions encountered include: the elastic deformation of clayey glaciolacustrine soils, shrink-swell properties, inadequate bearing capacities, and mass movements. These conditions are responsible for structural failures including the Fargo Grain Elevator in 1955 and the Northern Pacific railroad grade. Bank failures along the Red River are common due to the inherent instability of Brenna Formation smectitic clays which are subject to plastic deformation in the subsurface, with resultant block failure of overlying Sherack Formation. Recent alluvial sediments due to typical fluvial action and the continued seasonal saturation of cutbank meanders within the floodplain also add to soil instability.  相似文献   

浅覆盖区土壤化学成分与基岩化学成分的关系及其意义——以大兴安岭北部地区为例   总被引：3，自引：3，他引：3       下载免费PDF全文

郝立波  陆继龙马 力 《中国地质》2005,32(3):477-482

以大兴安岭北部地区为例，研究了浅覆盖区土壤与基岩化学成分的关系。指出浅覆盖区残积型土壤主要造岩元素组合继承了基岩元素组合特征；在岩石风化成土过程中，元素再分配和迁移使土壤中大多数元素（氧化物）含量产生明显的“均一化”。在此基础上，对土壤地球化学异常的识别与评价问题进行了讨论并提出了建议。  相似文献   

耒宜高速公路路堑边坡变形破坏特征及其综合治理   总被引：2，自引：2，他引：2  

肖剑秋  卿笃干  赵海斌  钟辉亚 《工程地质学报》2002,10(1):89-92

耒宜高速公路修建于山岭重丘区 ,沿线地形、地质条件差异较大 ,路堑开挖边坡类型较多 ,特征不一。本文介绍了路堑边坡的主要特征、边坡失稳的主要原因及治理对策。  相似文献   

圆弧状沉积盆地与软土单覆盖层出平面地表运动对比   总被引：2，自引：0，他引：2  

袁晓铭  李雨润  孙锐 《地震工程与工程振动》2002,22(4):16-21

采用解析方法，通过圆弧状沉积盆地与同样参数的软土均匀单覆盖层的对比，研究沉积盆地对平面SH波二维散射效应和其出平面地表运动。数值对比结果表明：（1）波垂直入射时盆地中央地表位移幅值反应，其随频率变化形式与软土单覆盖层的地表运动有较强的对应性，且此时单覆盖层地表位移幅值为其下降；（2）盆地的二维散射效应特点显著波的汇聚作用使盆地中的地表运动显著放大，总体上较软土单覆盖层的地表位移幅值要大，其频域内的最大反应则明显大于单覆盖层情况，但最大反应在盆地表面出现的位置依赖于入射波角度、盆地深宽比和盆地的软硬程度；（3）沉积盆地中地表位移运动有强烈扭转效应，且随盆地变软和入射波频率增高而增强。  相似文献