共查询到20条相似文献，搜索用时 656 毫秒
1.
崖腔型悬崖破坏,是一种崩塌地质灾害,对线路工程与居住环境的安全性必须进行评估。假设张应力呈线性三角形分布,提出了一种评估崖腔型悬崖体稳定性的估算方法：首先计算张力矩,应用张力矩与压力矩相等的力矩平衡原理,计算出张力面上的总张力,然后按张力线性分布原理求出最大张应力。崖腔型悬崖的破坏是顶部最大张应力拉裂岩石而发生的。所以稳定系数定义为抗拉强度与最大张应力之比,用以评价崖腔型悬崖的稳定性。用算例讨论了影响崖腔型悬崖张应力大小的因素：悬崖体厚度H、岩石容重γ与崖腔深度L,分析了它们对不同厚度岩体与不同崖腔深度条件下最大张应力变化与破坏的一般变化规律,以及节理裂隙发育程度对岩体抗拉强度的影响,并提出了相关建议。算例表明本方法与悬臂梁的弹性力学解方法结果相差很大,证明弹性力学解对“深梁”型悬崖是不适用的。 相似文献
2.
The undrained tunnel face stability in clay with a linearly increasing shear strength with depth was investigated by three-dimensional finite element analysis. Three parametric studies were performed to study the effects of the cover depth ratio, overburden stress factor and linear strength gradient ratio on the load factor of the undrained tunnel face stability. The influence of the linear strength gradient ratio on the predicted failure mechanism of the undrained face stability was discussed and examined. An approximate closed-form solution was proposed for three-dimensional undrained tunnel face stability in clays with constant or linearly increasing shear strength profiles with depth. 相似文献
3.
Rock slope response to strong earthquake shaking 总被引：1，自引：1，他引：0
C. Massey F. Della Pasqua C. Holden A. Kaiser L. Richards J. Wartman M. J. McSaveney G. Archibald M. Yetton L. Janku 《Landslides》2017,14(1):249-268
The 2010–2011 Canterbury earthquakes triggered many mass movements in the Port Hills including rockfalls, debris avalanches, slides and slumps, and associated cliff-top cracking. The most abundant mass movements with the highest risk to people and buildings were rockfalls and debris avalanches sourced from up to 100 m high cliffs inclined at angles >65°. Cliffs lower than 10 m in height generally remained stable during the strong shaking, with only isolated release of a few individual boulders. We used site-specific data to investigate the factors that controlled the response of the cliffs to the main earthquakes of the Canterbury sequence, adopting two-dimensional finite element seismic site response and stability modeling that was calibrated using the field observations and measurements. Observations from the assessed cliffs in response to the earthquakes show the taller cliffs experienced larger amounts of permanent cliff-top displacement and produced larger volumes of debris than the smaller cliffs. Results indicated a mean KMAX amplification ratio for all sites under study of 1.6 (range of 1.1–3.8). Field data and numerical modeling results, however, show that amplification of shaking does not necessarily increase linearly with increasing cliff height. Instead, our results show that accelerations are amplified mainly due to the impedance contrasts between the geological materials, corresponding to where strong differences in rock mass shear wave velocity exist. The resulting acceleration contrasts and rock mass strength control cliff stability. However, the amount of permanent slope displacement and volume of debris leaving the cliffs varied between the sites, due to site-specific geometry and rock mass strength. 相似文献
4.
日益严重的风化侵蚀,严重影响了莫高窟围岩的稳定性和壁画的赋存环境,成为威胁洞窟文物安全的严重隐患。为研究莫高窟北区崖体沿纵深方向的风化特征,选取莫高窟北区北侧一处崖体为试验点,采用逐层剖切的方法,沿水平方向由外向里依次取样编号。通过室内颗分试验、现场声波测试、可溶盐测试及X射线衍射测试,分析其变化规律。试验结果表明:地层颗粒组成的差异将影响崖体的抗风化能力;声波波速呈现震荡性的变化趋势;在水平深度0.7 m范围内钠长石含量相对减少,石英含量相对增加;崖体在水平深度0.4~1.0 m范围内可溶盐含量呈现递减特征;可溶盐是影响北区崖体风化的重要因素之一。综合分析各测试结果,认为1号、2号和3号探洞风化厚度分别为1.0 m、0.6 m和0.4 m。崖体风化呈现空间差异性,顶部风化最为严重,底部风化最弱。 相似文献
5.
昌马水库右岸山体稳定性研究 总被引：2，自引：0，他引：2
昌马水库导流排砂洞塌方导致右岸山体发生松动 ,本文在大量地质资料的基础上 ,对右岸岩体裂隙网络进行模拟 ,同时 ,采用极限分析能量法和有限元数值模拟方法等对右岸山体的稳定性进行分析研究 ,并提出相应的加固方案。 相似文献
6.
Stability Analysis of a Rock Column in Seismic Conditions 总被引：1，自引：0，他引：1
7.
Back analysis of an excavated slope failure in highly fractured rock mass: the case study of Kargar slope failure (Iran) 总被引：2，自引：1，他引：1
Mostafa Sharifzadeh Mohsen Sharifi S. Mohammad Delbari 《Environmental Earth Sciences》2010,60(1):183-192
This paper examines the failure of Kargar cut slope located at the south part of Esfahan subway using analytical and numerical
back analysis methods. The excavated trench has 27 m depth with near vertical walls due to the space limitation around it.
The geology of the area comprises weathered and heavily jointed shale and sandstone overlaid by alluvium deposits. Despite
the slope being supported by shotcrete and fully grouted rock bolts, a catastrophic failure occurred at the east wall. Due
to the uncertainty about the causes of failure initiation, back analyses have been performed via both the limit equilibrium
and numerical method for considering various probable mechanisms. In the back analysis with limit equilibrium method, the
rock mass is assumed as an equivalent continuum and Hoek–Brown failure criterion and geological strength index (GSI) are applied
to calculate the shear strength parameters. The results show that GSI value was 33 in the failed mass. In the numerical back
analysis, the distinct element method is applied to study the contribution of rock joints to the failure and progressive rock
mass strength degradation until failure. The results show that threshold values of joint cohesion and friction were 0.2 MPa
and 30°, respectively. Also the modeled slip surface being step-shaped agrees with the observed one. 相似文献
8.
Assessment of tunnel instability—a numerical approach 总被引：2，自引：1，他引：1
This paper outlines the application of numerical modeling to predict deformation and stability of tunnel to be excavated in Bansagar, M.P., India. To meet the ever-increasing demand of transportation, energy, and other infrastructure projects, a large volume of rock tunneling is being carried out throughout the world. The geotechnical properties along the route of the 1,800-m long tunnel in the Bansagar region of India have been studied. The rock mass rating and rock mass quality systems were employed for empirical rock mass quality determination. Numerical analysis for the stress–strain distribution of the tunnel excavation and support systems was also carried out. In order to simulate the excavation of tunnel (NATM) at a depth of 150 m below the ground , a series of finite element analyses using Mohr-coulomb elasto-plastic constitutive model has been carried out using PLAXIS 2D. The stability of tunnel has been analyzed, and stress pattern have been discussed. 相似文献
9.
丽香铁路金沙江特大桥位于金沙江虎跳峡镇高地震烈度深切峡谷地段。香格里拉端岸坡地形陡峻,卸荷裂隙发育,岸坡岩体在地震及工程荷载作用下的稳定性直接控制了桥梁选址方案的可行性。在深入分析对岸坡工程地质条件的基础上,基于节理特征分析的Barton模型、岩体结构面强度实验,讨论了岩体结构面强度参数,并在此基础上采用底摩擦实验研究了岸坡在自然和工程荷载作用下的稳定性,进而采用离散单元法计算分析了岸坡岩体在自然、桥基荷载作用下、地震加桥基荷载作用工况条件下的破坏趋势。研究表明,岸坡整体稳定,但在地震和桥梁荷载作用下,岸坡卸荷裂隙进一步发育,对桥基影响较大,应加强卸荷带岩体的工程整治以确保桥基安全。 相似文献
10.
Numerical modelling of rock slides is a versatile approach to understand the failure mechanism and the dynamics of rock slopes. Finite element slope stability analysis of three rock slopes in Garhwal Himalaya, India has been carried out using a two dimensional plane strain approach. Two different modelling techniques have been attempted for this study. Firstly, the slope is represented as a continuum in which the effect of discontinuities is considered by reducing the properties and strength of intact rock to those of rock mass. The equivalent Mohr-Coulomb shear strength parameters of generalised Hoek-Brown (GHB) criterion and modified Mohr-Coulomb (MMC) criterion has been used for this continuum approach. Secondly, a combined continuum-interface numerical method has been attempted in which the discontinuities are represented as interface elements in between the rock walls. Two different joint shear strength models such as Barton-Bandis and Patton’s model are used for the interface elements. Shear strength reduction (SSR) analysis has been carried out using a finite element formulation provided in the PHASE2. For blocky or very blocky rock mass structure combined continuum-interface model is found to be the most suitable one, as this model is capable of simulating the actual field scenario. 相似文献
11.
将非线性有限元分析和极限分析相结合形成强度参数折减有限元法,可以灵活地分析强度不均匀顺层路堑边坡支护结构稳定性问题。将岩体力学理论、非线性有限元分析技术和强度折减系数法相结合,对顺层岩体路堑边坡稳定性进行分析。在对密集假设节理有限元模拟中,假设节理在岩体内连续分布,采用连续介质力学方法建立密集分布节理岩体材料模型。采用强度折减系数法计算岩体结构安全系数,建议采用给定的岩体强度参数计算节理岩质边坡开挖、支护完毕后的内力,再逐渐降低岩体强度参数进行岩体边坡非线性有限元分析,直至岩体边坡达到极限状态,从而求出岩质边坡安全系数。采用该方法对渝怀铁路梅江河右岸DK409+989.4～DK410+020段顺层路堑边坡土钉墙支护结构稳定性进行分析,分析结果表明：采用土钉墙支护后的节理边坡塑安全系数为2.3,支护后的岩质边坡处于稳定状态;土钉墙潜在破裂面为岩体弹性区和塑性区的交界面,与测试得到的各排土钉拉力最大值位置一致。 相似文献
12.
深埋隧道地震动力响应的复反应分析 总被引：11，自引：5，他引：11
复反应法是用来分析地震动力作用下岩土体动力性质的有限元方法之一。这种方法的主要特点是引入复模量概念, 使材料的阻尼比与频率无关, 这样能更好的模拟岩土体的动力性能。本文结合在建的某公路深埋隧道, 分析了隧址区山体的地震动作用特点, 探讨了隧道埋深与地震作用强度之间的关系。 相似文献
13.
高地应力下硬岩的本构模型研究 总被引：1，自引：0，他引：1
传统的本构模型在模拟高地应力下硬岩破坏的范围和深度方面并不理想。针对高应力下的拉西瓦花岗岩,通过真三轴压缩试验模拟了开挖时应力路径的演化。在摩尔-库仑强度准则、格里菲斯强度准则、德鲁克-普拉格准则、双剪统一强度理论和霍克-布朗强度准则的基础上,考虑十二面单元体主剪面上主剪应力、正应力和静水压力的共同作用,提出了一个有关高应力下硬岩的三剪强度准则。根据试验结果,利用遗传算法全局寻优的功能,搜索出了三剪强度准则的参数。预测样本和与摩尔-库仑强度准则、德鲁克-普拉格准则、双剪统一强度理论的比较表明,该三剪强度准则与试验结果吻合,适用于高地应力下的硬岩。根据试验得到的应力-应变关系曲线,建立了基于三剪强度准则和应变软化的弹-脆-塑性本构模型,并用FLAC3D提供的基于C++的用户自定义模型工具UDM,创建了用户自定义模型的动态链接库,嵌入了FLAC3D软件。采用遗传算法-FLAC方法,搜索得到了基于岩石试样和岩体的本构模型参数。计算结果与实测情况吻合,表明建立的本构模型适用于高地应力下的硬岩,为高地应力下硬岩地下工程的安全性和稳定性分析奠定了基础。 相似文献
14.
本文介绍了天福庙拱坝坝肩岩体稳定性研究,并提出了相应加固措施的建议。即在详尽的工程地质水文地质调查的基础上分析出各种可能的失稳机制,并组合出各种滑移边界条件;通过现场和室内岩体力学试验,测出构成边界条件的各种地质结构面的抗剪强度和变形常数;通过三维有限元弹性分析计算,得到应力应变和破损区的分布,检验了失稳机制和边界条件的合理性;通过刚体极限平衡法,计算出各种荷载和边界条件组合情况下的抗滑稳定安全系数;尔后针对最不稳定边界条件及其控制稳定性的主要因素,提出有效的加固措施的建议。文中还讨论了岩体和各种软弱结构面抗剪强度的取值原则、试验值的使用原则以及非均质结构面和组合结构面的综合抗剪强度问题。 相似文献
15.
16.
某边坡变形破坏机理的数值分析 总被引：3，自引：0，他引：3
某花岗岩矿岩土体主要有填土、粉质粘土、淤泥及淤泥质土、含泥中粗砂、粘土、残积砂质粘土,其下为花岗岩基岩。边坡最大高度75m,其中残积土层以上的土质边坡高度约50m。本文运用有限元强度折减法对该边坡的稳定性进行了研究,得出了潜在的破坏模式及各个滑动部分的安全系数。分析结果表明,本边坡存在3个潜在滑动面,其中两个为浅层滑动面,另一个为深层滑动面。两个浅层滑动面的稳定系数在1.13～1.17,处于临界状态。深层滑动面稳定性系数在1.29,目前尚处在相对稳定状态。根据分析结果,提出了如下加固措施:（1）对滑坡体进行削坡处理;（2）在其滑动面下方设置抗滑台阶;（3）采用预应力锚索框架梁结合肋柱进行加固处理。 相似文献
17.
滇藏铁路香格里拉—邦达段沿线断层发育,构造运动强烈,为提高沿线工程的稳定性,基于构造形迹、震源机制解和实测数据的多元综合分析法,对研究区主应力方向进行了分析;基于Hoek-Brown强度准则和修正的Sheorey理论,结合实测数据,对研究区岩体强度参数和主应力量值进行了估算和预测,最后对研究区的地应力场特征及其工程效应进行了分析。结果表明:香格里拉-德钦应力区的水平最大主应力方向N0°W~N40°W;芒康-邦达应力区的水平最大主应力方向为N60°E~N80°E;铁路沿线埋深1000 m处,水平最大主应力范围为24.23~37.30 MPa;埋深2000 m处,水平最大主应力范围为47.29~66.69 MPa;香格里拉-德钦应力区隧道轴线设置为N80°W~N40°E有利于围岩稳定,芒康-邦达应力区隧道轴线走向设置为N10°E~N130°E有利于围岩稳定;铁路沿线高地应力显著,埋深超过400 m就可能处于高地应力状态,硬质岩埋深超过700 m会有岩爆风险,软质岩埋深超过1400 m会有大变形风险。 相似文献
18.
危岩是三峡库区典型的地质灾害类型之一,而主控结构面受荷断裂扩展是危岩发育成灾的关键核心。将危岩主控结构面类比为宏观裂纹,利用扩展有限元法在模拟裂纹扩展方面的优势,基于考虑裂纹面水压力作用的虚功原理推导出了采用扩展有限元法分析水力劈裂问题的控制方程,给出了危岩主控结构面水力劈裂问题的扩展有限元实现方法,对重庆万州太白岩危岩主控结构面的水力劈裂进行了数值模拟分析。计算结果表明：暴雨是威胁危岩稳定性的最敏感因素,随着裂隙水压力上升,裂端拉应力会急剧升高,危岩的稳定性降低;I型裂纹扩展是危岩主要的结构面扩展形式,结构面一旦发生开裂,将处于非稳定扩展状态。 相似文献
19.
将有限元强度折减理论应用于边坡稳定性分析中,运用ANSYS大型有限元分析软件,基于Drucker-Prager（D-P）屈服准则,采用力和位移的收敛标准作为破坏判据,进行边坡的稳定性分析。当折减系数达到某一数值时,非线性有限元静力计算将不收敛,滑面上的位移将产生突变,边坡内一定幅值的广义剪应变自坡底向坡顶贯通,此时认为边坡已破坏,并定义此时的折减系数即为稳定系数。文中以韩城煤矿节理岩质边坡为例,运用该方法进行了稳定性分析并与并与传统的Bishop法、Janbu法等方法对比。计算结果表明,有限元强度折减法能更加真实地反映边坡的实际情况,求得的边坡稳定系数更接近边坡的实际稳定状态,显示出其在边坡稳定性分析中的一定优势。 相似文献
20.
采用有限元方法探讨在人工开挖或自然侵蚀环境下,岩质边坡体内应力场的变化及节理发育形成机理,并采用有限元强度折减法对后缘具有张节理边坡的稳定性影响因素进行敏感性对比分析,进而得出具有非贯通节理边坡稳定性计算的修正解析解。结果表明：卸荷及风化作用导致边坡体由表及里出现应力重分布及应力集中的现象,使边坡后缘由顶部向下发育一簇竖直向下或略向临空面倾斜的张节理,当张节理与下部的缓倾剪节理贯通时,边坡发生破坏;边坡稳定性最敏感的影响因素为受剪节理的倾角及贯通度,其次是节理的强度参数;可将工程中较难调查的节理贯通度转化为节理的强度参数来等效表达,并根据Mohr-Coulomb强度准则推导得到适用于具有非贯通节理的岩质边坡稳定性的修正解析解。 相似文献