排序方式： 共有71条查询结果，搜索用时 15 毫秒
61.
Hoek-Brown准则参数在边坡工程中的敏感性分析 总被引：2，自引：0，他引：2
Hoek-Brown屈服准则是估计完整岩石或节理岩体剪切强度的半经验准则,已成为岩体强度预测及稳定性分析领域应用最广泛的准则之一。选取常见的3类岩石材料作为分析代表,通过有限差分法及敏感性分析方法研究了Hoek-Brown准则中各参数对岩质边坡安全系数的灵敏度。研究表明,地质强度指标GSI对岩质边坡稳定性影响最为显著,而反映岩石的软硬程度材料常数mi、岩体扰动系数D和岩石单轴抗压强度?ci影响显著性要小于地质强度指标。最后,对GSI对岩体的摩擦角? 和凝聚力c的影响规律进行了分析。结果表明,对于同一GSI,mi从小到大变化时,? 的变化幅度在减小,GSI值在55附近时,不同mi所对应的凝聚力趋于同一个值。 相似文献
62.
基于非线性屈服准则及主应力判据的圆形巷道围岩岩爆过程的数值模拟 总被引：1，自引：0，他引：1
鉴于考虑拉伸截断的线性莫尔-库仑屈服准则不能考虑岩石在高应力条件下的非线性屈服特征,根据虎克-布朗本构模型,将上述屈服准则在受压区的线性屈服函数修改为非线性形式。采用3种岩爆的主应力判据,判别圆形巷道开挖之后围岩中各种级别岩爆的分布及演变规律。计算采用＂先加载,后挖洞＂的方式,岩石服从弹—脆—塑性本构模型。研究发现,发生高级别岩爆的单元数少于发生低级别岩爆的单元数;轻微岩爆区的形态更接近于塑性区及剪切应变增量的高值区。根据巴顿判据,发生重岩爆的单元数较多,而且主要发生的是拉伸岩爆;根据陶振宇判据,发生轻微及中等岩爆的单元数均多于根据谷明成-陶振宇判据判别的结果。上述两种判据判别的结果均表明,在不考虑拉伸岩爆的条件下,只有位于围岩内部的单元才有可能发生高级别的岩爆,而位于巷道表面的单元一般仅发生轻微岩爆。 相似文献
63.
深埋隧洞围岩变形是一个复杂的非线性力学问题,其中岩石的蠕变全过程和扩容是两个重要的影响因素。引入扩容角考虑塑性体积变化的影响,推导Hoek-Brown屈服准则下考虑与不考虑洞周面力的深埋隧洞围岩非线性应力解。借助可描述蠕变全过程行为的河海模型,获得了围岩黏弹塑性区蠕变位移表达式。针对不同NVPB蠕变参数和不同材料参数m值情况,讨论分析了洞周面力与扩容角对隧洞洞壁蠕变位移的影响规律。结果表明：在高地应力作用下,采用非线性蠕变模型描述深埋隧洞围岩蠕变问题可获得蠕变全过程曲线;扩容角增大或洞周面力和材料参数m值减小时,相同时刻隧洞洞壁蠕变位移增大,对围岩长期稳定不利。研究结论对深埋隧洞围岩临崩预报具有一定指导意义。 相似文献
64.
为考虑中间主应力对岩石极限破坏强度作用,在广义Hoek-Brown强度准则幂率项中添加定量表征中间主应力项,构建新的三维Hoek-Brown强度准则。该准则在主应力空间是通过3个角点外接Hoek-Brown准则包络面的曲六面体,在 空间包络线是幂律型曲线。通过与Hoek-Brown准则、Drucker-Prager准则和Mogi准则分别对4组真三轴压缩强度试验数据的拟合对比分析,探讨其反映中间主应力效应的适用性。结果表明,修正的Hoek-Brown强度准则拟合试验数据效果总体最好,Mogi准则次之,Hoek-Brown准则和Drucker-Prager准则较差。从而修正的Hoek-Brown强度准则最适用于粗面岩、大理岩和花岗岩等硬脆性岩石的真三轴强度预测及中间主应力影响规律描述。 相似文献
65.
为了研究渗透水压力和轴向应力共同作用时隧道围岩的应力和位移变化趋势,将圆形隧道简化为轴对称模型,假定渗透场以渗透体积力作用在原应力场,以围岩开挖断面为假定平面,引入垂直于该平面的轴向应力。基于广义Hoek-Brown强度准则和非关联流动法则,推导出考虑轴向应力和渗透场共同作用时弹-脆-塑性围岩的应力和位移非线性解,采用数值算例分析了轴向应力和渗透力共同作用时隧道围岩塑性区应力场和位移场的分布规律。计算结果表明：与无渗透水压力作用下的模型相比,渗透力作用使得围岩塑性区各点位移增大,并且内外水头差越大,位移增大越明显。当轴向应力为中主应力时,围岩塑性区半径和塑性区各点应力增大,轴向应力为大主应力和小主应力时,围岩塑性区半径和塑性区应力变化较小。因此,渗透力的存在不利于隧道围岩的稳定性,并且轴向应力的大小对于富水地区隧道围岩的应力和位移分布具有较大影响。在施工设计时考虑渗透力以及轴向应力的共同影响对于保证隧道围岩稳定性具有重要意义。 相似文献
66.
为深入探究岩体非线性软化应变特性对隧洞围岩力学行为的影响,提出了一种考虑软化系数的岩体弹塑性软化模型,并推导了圆形隧洞围岩应力-应变的求解方法。然后,通过将本文方法与Brown方法、换算后的Mohr-Coulomb屈服准则方法进行对比,验证了本文方法的合理性。最后,探究了软化系数对围岩变形及支护压力影响规律。结果表明：软化系数较大时,采用弹塑性软化模型与弹脆塑性模型算得结果基本相同;对围岩变形及稳定性起主要控制作用的是松动区域范围;控制塑性区域出现时的临界支护压力在数值上与弹塑性区域交界处径向应力是相等的。 相似文献
67.
云锡大屯锡矿岩体力学参数的确定 总被引：5，自引：0，他引：5
阐述了岩体力学参数研究的重要性,系统地介绍了几种国内外常用的岩体力学参数的确定方法及其原理。以云锡大屯锡矿岩体力学参数研究为例,并以其室内试验得出的岩石物理力学参数和岩体质量评价RMR值为基础,采用这些方法对岩石物理力学参数进行工程折减弱化处理,计算得出其岩体力学参数。其结果对比分析及其推荐值的工程应用结果表明：将最新的Hoek-Brown准则、室内试验、M.Georgi法和费森科法四者相结合来进行分析,得出的岩体力学参数更为合理,提高了工程岩体力学计算精度。 相似文献
68.
Determination of Shear Strength and Three-dimensional Yield Strength for the Hoek-Brown Criterion 总被引：1，自引：3，他引：1
S. D. Priest 《Rock Mechanics and Rock Engineering》2005,38(4):299-327
Summary. Most currently used techniques for analysing the stability of near surface structures, such as rock slopes, are based on the application of the effective Coulomb shear strength parameters cohesion c′, and the angle of friction φ′ on some known or anticipated shear surface subjected to an effective normal stress σ′n. The most widely used of these techniques are the variants of the method of slices and related upper bound techniques. If the Hoek-Brown criterion is to be used to model the strength of near surface fractured rocks, it is necessary to determine equivalent Coulomb shear strength parameters for the specified level of effective normal stress. Calculation of the equivalent Coulomb parameters for the Hoek-Brown criterion for cases when a ≠ 0.5 is not a straightforward matter. A simple procedure for calculating instantaneous values of c′i and φ′i has been developed based on spreadsheet calculations and the application of a numerical optimisation routine. This procedure can also be applied to calculating the Hoek-Brown envelope plotted in shear stress/normal stress space. A simple closed form solution for c′i and tan φ′i has also been developed for the special case when a = 1. A three-dimensional version of the Hoek-Brown criterion has been developed by combining it with the Drucker-Prager criterion. This new yield criterion has been implemented by numerical solution of the governing equations. A simplification of this three-dimensional yield criterion has been developed by introducing an intermediate principal stress weighting factor. Comparison with published results demonstrates that this simplified criterion has the capacity to model the results of true triaxial tests for a range of different rock types over a wide range of stress levels. The new three-dimensional yield criterion has the advantage that its input parameters can be determined from routine uniaxial compression tests and mineralogical examination. 相似文献
69.
Analysis of support requirements for a shallow diversion tunnel at Guledar dam site, Turkey 总被引：2，自引：0，他引：2
Engineering geological properties and support design of a planned diversion tunnel at Guledar dam site, which was located at the North of Ankara, Turkey were studied in this article. The main purpose of the construction of the planned tunnel is to regulate, drainage and to provide water for irrigation purposes. The diversion tunnel runs mainly through formations of limestone, sandstone and diabase. Rock masses at the site were characterized using Rock Mass Rating (RMR), Rock Mass Quality (Q), Rock Mass Index (RMi) and Geological Strength Index (GSI). RMR, Q, RMi and GSI were determined by using field data and mechanical properties of intact rock samples, measured in the laboratory. Support requirements for the planned diversion tunnel were determined accordingly in terms of the rock mass classification systems. Recommended support systems by empirical methods were also analyzed using 2D Finite Element method. Calculated parameters based on empirical methods were used as input parameters in the finite element models. The results from both methods were compared with each other. This comparison suggests that more reliable support design could be achieved by using the finite element method together with the empirical methods. 相似文献
70.
基于Hoek-Brown（H-B）准则，根据大量试验数据，研究提出一种具有广泛适用性的岩石应变软化模型。利用40种硬岩和软岩三轴试验数据，验证了3参数幂函数型围压函数广泛适用于硬岩和软岩峰后临界塑性应变与围压的关系描述，并将其引入塑性内变量中；其次，比较分析当前基于H-B准则的岩石应变软化模型中软化参数的合理性，明确以GSI作为软化参数的方法最优，拟合结果正确且参数最少。然后，分析岩石峰后GSI随塑性内变量的演化规律，并建立一种普适的非线性演化模型。与其他演化模型相比，所建模型可更准确地描述不同种类岩石峰后H-B强度参数的非线性演化规律，同时参数较少。接着，采用非关联流动法则，将所建GSI演化模型嵌入有限元软件ABAQUS中，实现软化模型的数值求解。最后，对多种岩石的室内试验模拟结果表明，所建模型可正确描述不同围压下硬岩和软岩的峰后应变软化变形及剪胀变形，具备良好的适用性。与定临界塑性应变或定剪胀角的应变软化模型模拟结果相比，所建模型模拟曲线可一致性地与试验曲线接近。 相似文献