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141.
山区河道溃坝水流数值模拟 总被引:1,自引:0,他引:1
为了研究溃坝水流在山区河道中的传播,采用SPH方法来求解2维浅水方程,建立了溃坝水流数值模型.SPH方法由于是拉格朗日法,在处理对流主导的问题具有很好的稳定性与精度,且是无网格方法,无需划分网格和判定干湿网格,很好地解决了山区河道溃坝水流流速急,水位变幅大,动边界变化频繁,计算区域难确定等问题.采用该模型模拟了山区河道的溃坝水流,初步再现了溃坝水流的流动过程,分析表明模拟结果是合理的,因而采用SPH方法对溃坝水流进行模拟是可行的. 相似文献
142.
Jian Liu Xia-Ting Feng Xiu-Li Ding Jie Zhang Deng-Ming Yue 《International Journal of Rock Mechanics and Mining Sciences》2003,40(5):609-631
Foundation stability is one of the most important factors influencing the safety of a concrete dam and has been one of the key technical problems in the design of the Three-Gorges Project. The major difficulties lie in two facts. The first one is that the dam foundation consists of rock blocks, with joints and so-called ‘rock bridges’ and the gently dipping joints play a critical role in the foundation stability against sliding. The second one is that, even in the regions where the gently dipping fractures are most developed, there are no through-going sliding paths in the rock mass due to the existence of the rock bridges; so the dam could slide only if some of the rock bridges fail, so as to create at least one through-going sliding path. To date, due to unavoidable shortcomings in physical and numerical modeling techniques, there is not a single satisfactory method to solve the problem completely. For this reason, the integration of multiple methods was adopted in this study and proved to be an effective and reliable approach.This Part I paper describes work based on the results of geological investigations and mechanical tests, relating to the geological and geomechanical models of the Three-Gorges Dam, and then a systematic study procedure was developed to carry out the stability assessment project. Then, 2D and 3D physical model tests for some critical dam sections were performed. In the physical tests, based on similarity theory, various testing materials were selected to simulate the rock, concrete, fracture and rock bridge. The loading and boundary conditions were also modeled to meet the similarity requirements. The failure mechanism was derived through a progressive overloading that simulated the upstream hydrostatic pressure applied to the dam, and the factor of safety was defined as the ratio between the maximum external load inducing the start of sliding instability of the dam foundation and the upstream hydrostatic load. The experimental results indicated that the stability of the Three-Gorges Dam foundation satisfies the safety requirements. Nevertheless, further discussions demonstrated that because of the incomplete definition of factor of safety adopted in the physical model tests, it is also essential to study the stability of the Three-Gorges Dam foundation using numerical modeling, which will be presented in the companion Part II paper. 相似文献
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混凝土面板坝的安全与面板的受力状态密切相关。混凝土面板与砾石垫层料的特性有较大差异,两者之间接触面的力学特性,对于面板的应力与变形具有重要影响。结合国内在建的水布垭高面板堆石坝的设计科研需要,研制了一大型叠环式单剪仪,对面板与砾石垫层间接触面的力学特性进行了试验研究。为了对接触面的不同处理方式的效果进行对比,为设计方案的选择提供依据,分别进行了混凝土面无保护、砂浆保护和乳化沥青保护三种接触面的剪切试验。 相似文献
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主要着重叙述了虹吸管在德兴铜矿4#尾矿库1#斜槽及隧洞封堵施工期间为选矿厂供应回水中应用实践过程。通过虹吸管设施和应用,为1#斜槽及隧洞封堵工程的施工顺利进行,为满足选矿厂生产用水补给和稳定矿山正常的生产秩序及生产计划的完成奠定了基础,并且取得了良好的经济效益。 相似文献
147.
Probability and Risk of Slope Failure 总被引:1,自引:0,他引:1
Francisco Silva T. William Lambe W. Allen Marr 《Canadian Metallurgical Quarterly》2008,134(12):1691-1699
This paper aims to demystify the use of risk assessment as a decision management tool and present a methodology that places quantitative risk assessment within reach of every geotechnical engineer, even for routine engineering assignments. In particular, we propose using quantification of expert judgment (i.e., subjective probabilities) as a practical alternative for determining probability of slope failure. The writers present a semiempirical relationship between factor of safety and annual probability of failure that permits estimation of slope failure probabilities with relatively modest effort. The case study for a tailings dam shows that risk assessment based on quantification of expert judgment provides a framework to arrive at rational management and engineering decisions related to dam safety and other geotechnical problems. Using the semiempirical relationship presented here, practicing engineers can use this helpful tool by applying their current skills. 相似文献
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为分析不同因素对城陵矶水位变化的贡献率,基于1955~2014年实测水文资料,利用Mann-kendall检验法、回归分析等方法分析城陵矶水位变化特征及其成因。结果表明,下荆江裁弯和葛洲坝的运行对城陵矶水位流量关系造成较大影响,同流量下城陵矶水位增幅明显,而三峡水库对城陵矶水位流量关系影响不大;1972~2002年水位流量出现"此消彼长"的现象,主要是因为干流顶托作用加强和断面逐年淤高对水位的抬高值大于因流量减小对水位的减小值所致;城陵矶水位于1967年发生突变,这与1967年中州子裁弯有一定联系,而四水入湖流量的减少是1977年流量发生突变的主要原因;通过构建模型,计算得出下荆江裁弯、葛洲坝和三峡水库的运行在各自所在时期对城陵矶水位变化的贡献率分别为50.3%、50.5%、56.8%。 相似文献