共查询到17条相似文献,搜索用时 203 毫秒
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采用各向异性强化-软化的有厚度薄层单元模拟了坝基软弱夹层的力学变形特性,采用无厚度接触摩擦单元模拟坝基岩体节理裂隙,对高混凝土重力坝复杂坝基抗滑稳定采用三维非线性有限元分析,利用强度储备系数法模拟坝体坝基系统的渐进破坏过程、可能失稳模式,提出了塑性屈服区贯通的强度分析方法、典型特征点位移突变的变形体分析方法以及能量法联合判定坝体坝基系统极限承载力的研究方案,得出了坝体坝基系统的极限承载力。最后针对建设中的向家坝水电站高重力坝的深层抗滑问题进行了三维非线性有限元分析,计算结果表明,系统的极限承载能力由夹泥层的强度控制,极限状态的强度储备系数为2.7。 相似文献
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重力坝的深层抗滑稳定分析多采用刚体极限平衡法和非线性有限元法,但刚体极限平衡法不能反映坝基岩体渐进失稳过程和破坏的力学机制,非线性有限元法模拟岩体不连续效率低,且还未有统一的失稳判据。基于离散块体边界应力计算结果,提出重力坝坝基多滑面抗滑稳定安全系数计算公式,并探讨了以坝体-坝基系统能量突变作为坝基失稳判据的物理意义。通过与非线性有限单元法、刚体极限平衡法计算结果的比较,验证了所提方法及判据的可靠性及合理性。结合向家坝水电站重力坝泄12#坝段进行计算分析,结果表明:基于离散元强度储备系数法搜索的坝基失稳通道由坝基岩体屈服区和结构面滑移带组成,所提计算方法与判据适用于实际工程的坝基深层抗滑稳定计算分析,且计算结果偏安全。 相似文献
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连通率是岩体内部结构面发育尺寸及贯通程度的重要指标,决定着岩体的工程力学特性,对边坡、坝基等工程岩体的整体强度和稳定性评价等发挥着至关重要的作用。以西南地区某水电站拱坝建基典型岩体缓倾结构面为研究对象,根据现场岩体实测数据,基于自行开发的裂隙网络模拟程序,采用蒙特卡洛(Monte-Carlo)随机模拟方法对水电站左、右岸岩体不同剪切方向下缓倾结构面的连通率和岩体强度参数开展研究。研究表明:该水电站左、右岸岩体在不同剪切方向上的连通率是不同的,通过不同方向的角度旋转,总体获得的裂隙连通率较低;水电站右岸平洞PD02处缓倾角结构面的裂隙连通率约在27.35%左右,摩擦系数为1.04,黏聚力为0.89 MPa。研究成果可为水电工程建设提供理论参考和借鉴。 相似文献
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重力坝的深层抗滑稳定分析多采用刚体极限平衡分析方法和非线性有限元法,但通常的刚体极限平衡法不能反映坝基岩体渐近失稳过程和破坏的力学机制,非线性有限元法则难以解决坝基中软弱结构面位移不连续问题。结合向家坝工程,建立了泄④坝段的计算模型,采用界面元法进行了大坝深层抗滑稳定分析,给出了坝基中破坏区的范围和分布,以及坝基的渐进破坏过程和可能滑体的抗滑稳定安全系数等成果,为坝基处理措施提供了重要的技术参考依据。研究结果表明,所建立的分析方法可以自然描述坝基岩体各种介质的错动、张开和滑移等不连续变形的特征,可用于重力坝坝基的深层抗滑稳定 分析。 相似文献
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某水电站位于雅鲁藏布江中游桑日至加查峡谷段出口处,坝型为混凝土重力坝,最大坝高116m,属高坝。混凝土重力坝主要是依靠坝体自身重量于基础之上产生的摩擦力及坝体与基础之间的凝聚力来抵抗水压力以满足稳定要求,对基础岩体要求较高。根据该水电站坝基工程实践,从坝基岩体质量评价方法、分级标准及深层抗滑稳定计算方法等方面进行一些有益探索,对类似工程坝基岩体质量评价及深层抗滑稳定计算具有指导意义。 相似文献
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一种基于安全因子判据的坝肩裂隙岩体动力抗滑稳定分析方法 总被引:1,自引:0,他引:1
基于某混凝土拱坝,结合现行拱坝设计规范,研究提出了一种基于安全因子判据的坝肩岩体动力抗滑稳定安全度分析方法。该方法综合利用有限元和(刚体)极限平衡两种方法的优点,考虑了凝聚力和摩擦力是不同的抗力,其不确定性具有较大差异性,定义了抗滑稳定安全因子,据此来判别坝肩岩体的抗滑稳定安全度,安全因子随着凝聚力与摩擦力所占权重不同而变化,这种方法既考虑了坝肩岩体与坝体的联动作用,又能够反映拱坝体系真实的工作性态。通过某混凝土高拱坝工程实例,分析了坝肩裂隙岩体的抗震稳定性,结果表明,该方法具有较高的实用价值。 相似文献
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This paper presents the numerical and experimental investigation of a dam foundation. The site consists of granite and especially
weathered granite. Numerical and analytical analyses have been conducted to evaluate suitability of the granite for a dam
foundation. Mohr–Coulomb failure criterion has been used to calculate the compressive strength of the rock mass. Finite element
implementation of Mohr–Coulomb criterion has been used for deformation and settlement analysis. Packer testing and in-situ
estimation of rock mass deformability using the Goodman jack have been performed. The results of the evaluations show that
very small normal and differential settlements can be expected in structural regions due to dam construction, and the compacted
concrete dam can safely be constructed on either the competent granite or the weathered granite. However, the dam foundation
on the weathered granite has high conductivity potential problems for the reservoir. 相似文献
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This paper describes the results of the engineering geological investigations and rock mechanics studies carried out at the proposed Uru
Dam site. Analyses were carried out in terms of rock mass classifications for diversion tunnel, kinematic analysis of excavation slopes, permeability of the dam foundation and determination of rock mass strength parameters.Uru
Dam is a rock-filled dam with upstream concrete slab. The dam will be built on the Suveri River in the central part of Turkey. The foundation rocks are volcanic rocks, which consist of andesite, basalt and tuff of Neogene Age. Studies were carried out both at the field and the laboratory. Field studies include engineering geological mapping, intensive discontinuity surveying, core drilling, pressurized water tests and sampling for laboratory testing.Uniaxial, triaxial and tensile strength tests were performed and deformation parameters, unit weight and porosity were determined on the intact rock specimens in the laboratory. Rock mass strength and modulus of elasticity of rock mass are determined using the Hoek–Brown empirical strength criterion. Rock mass classifications have been performed according to RMR and Q systems for the diversion tunnel.Engineering geological assessment of the proposed dam and reservoir area indicated that there will be no foundation stability problems. Detailed geotechnical investigations are required for the final design of the dam. 相似文献
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岩体结构面的抗剪强度是表征岩体强度的一项重要参数,但由于原位试验受场地等诸多因素影响,难以大规模的开展,本文提出在室内用结构面大型剪切试验开展结构面的剪切特性研究,以某水电站坝基砂岩岩体中的硬性结构面为研究对象,取得了较好的成果。试验表明:结构面的多组剪切变形曲线具有一定的应变硬化的特征;达到峰值剪切强度时的剪切位移普遍较大,在8.9mm~44.5mm之间;砂岩中硬性结构面光滑面的基本摩擦角为31.4,结构面平均起伏角为6.3。 相似文献
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查明坝基岩体的渗透结构对于大坝工程防渗方案的制定具有重要意义。以黄河古贤水利枢纽工程近水平分布的红层坝基岩体为研究对象,使用“连续、高分辨率”压水试验数据处理与统计方法,分析了岩体透水率与高程、岩性及顺层剪切带的关系,阐明了坝基岩体的渗透结构,提出了工程防渗建议。研究发现,坝基岩体渗透结构表现出结构性和随机性双重特征。结构性表现为岩体透水率随高程的降低而减小;随机性表现为岩体透水率会因岩性和剪切构造等随机变化。对于河床及滩地坝基岩体,风化卸荷带底高程在450 m附近,1 Lu关键透水率指标界线的底高程位于340 m附近。对于岸坡坝基岩体,3 Lu关键透水率指标界线的底高程位于560~580 m。在坝基勘察深度范围内,350~360 m高程段连续分布具有一定厚度的软岩类岩体,剪切构造不发育且岩体透水微弱,可视为相对隔水层,对坝基防渗帷幕优化设计具有指示意义。文章提出的统计、分析方法具有一定普适性,可为类似工程所借鉴。 相似文献
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Lithological information, rock mass fracture data and discontinuity shear strength obtained through field investigations have been used to conduct kinematic and block theory analyses for the rock slopes that exist in the dam site to evaluate the stability of the slopes. The analyses were performed using mean discontinuity set orientations for each rock mass region under gravitational loading to calculate the maximum safe slope angles (MSSA) for different cut slope directions. Results show that final MSSAs obtained from kinematic analysis are less than or equal to that obtained from block theory analysis. The following conclusions have been made based on the block theory analysis results, which are closer to the reality: (1) The final MSSA range between 30° and 47°, 44° and 70°, 47° and 69° for cut slope dip directions of 20–30°, 105–210°, and 270–355°, respectively; (2) For cut slope dip directions of 20–30°, 200–210° and 275–315°, wide ranges of values have been obtained for the final MSSA reflecting the influence of variability of fracture orientations on MSSA; (3) Apart from the region R-d-1 for slope dip directions in the range 20–30°, rest of the regions at the dam site seem to be stable for slope angles less than 40°. Detailed comparisons are given between the kinematic and block theory analyses covering both the theoretical concepts and application results. Also a brief comparison is included between the laboratory and in situ discontinuity shear strength results. 相似文献