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排序方式: 共有1686条查询结果,搜索用时 15 毫秒
1.
本文选择大连市中山区长利巷地区的边坡,通过现场采取岩土样,进行室内试验得出各地层力学物理参数,对边坡进行稳定性分析。针对目前所拥有的模拟软件与方法,分析并筛选出适合该边坡的模拟软件。利用GeoStudio软件建模、模拟,使用Morgenstern-Price方法进行计算,通过分析得到计算结果,该边坡的安全安全系数为1. 127,认为其属于不稳定边坡。对于不稳定边坡,本文对主流的边坡支护方法进行分析筛选,拟采用扶壁式挡土墙支护方案对其进行预防。根据规范设计挡土墙尺寸,并对该挡土墙进行抗倾覆抗滑移验算,得出的验算安全系数满足规范要求,由此可得知该支护方案方法合理,技术可行。 相似文献
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为提高混凝土剪力墙受弯性能计算的准确度,开展强震下混凝土剪力墙受弯性能试验研究。选取1个混凝土剪力墙对比试件和3个测试试件作为研究对象,对试件施加垂直荷载和水平荷载,模拟强烈地震作用力。试验前期准备工作完成后,建立分离式有限元模型,通过计算混凝土在受压和受拉状态下的损伤弹塑性刚度,完成对有限元模型中混凝土塑性损伤分析,在此基础上,计算混凝土剪力墙受弯承载力。利用有限元模型对3个测试试件进行模拟试验,结果表明,强烈地震后3个试件的荷载-位移曲线均与实际位移值接近,且混凝土剪力墙受弯承载力试验结果与实际值的误差在2%以内,表明试验研究方法具有一定的可行性,数值模拟结果较为准确。 相似文献
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高土石心墙坝的渗透稳定性在很大程度上依赖于反滤层对心墙料的反滤保护作用。心墙在大坝蓄水和长期运行的条件下,要经历复杂的填筑加载、浸水饱和与水荷载的作用,在差异沉降、复杂结构应力作用、水力劈裂和渗透水流作用下,心墙一旦出现裂缝,其渗透稳定性及反滤层的保护作用就将面临严峻的考验。针对这一问题,设计了专门非常规的抛填土料反滤试验和泥浆渗透反滤试验,模拟心墙裂缝条件下其颗粒被冲刷起动后,被反滤料阻挡和淤积过程。试验结果表明,心墙料和反滤料满足反滤准则条件下,心墙颗粒被拦截和淤积在反滤层上游表面,反滤料能有效防止心墙颗粒的流失,反滤层在极端条件下对心墙料仍能起到有效的反滤保护作用。 相似文献
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为了研究三维壁面紊动射流前方布置的垂直挡板对时均流动特性的影响,采用粒子图像测速技术对不同雷诺数和淹没水深条件下的流速场进行了测量,统计分析了U速度剖面分布、速度半宽值变化和最大速度衰减规律。结果表明:沿射流方向具有3个明显不同的衰减区,依次划分为自由边界下的三维壁面射流区(Ⅰ区)、垂直挡板影响区(Ⅱ区)和近壁区(Ⅲ区)。在重点分析的Ⅱ区内,3个特征物理量的分布规律均与雷诺数无关;在垂直挡板影响下,速度半宽值扩展率明显加快,发展更为充分;在水深H~1.75H范围内,射孔中垂面内速度半宽值扩展率为0.043,同时0.5H的递增对射孔中心水平面内速度半宽值的分布较为敏感,其扩展率由0.205增至0.270;最大速度衰减对水深的改变并不敏感,且在Ⅱ区加速衰减,衰减指数为1.095。通过与半无限空间中三维壁面射流径向型衰减区的流动特征比较,Ⅱ区与之相似,将Ⅱ区视为提前进入径向型衰减区。 相似文献
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Seismic design and testing of the bottom vertical boundary elements in steel plate shear walls. Part 1: design methodology 下载免费PDF全文
This research investigates the seismic design method and the cyclic inelastic behavior of the bottom column, also called the vertical boundary element (VBE), in steel plate shear walls (SPSWs). This study consists of two parts. This Part 1 paper discusses the anticipated pushover responses for properly designed SPSWs and the possible inelastic responses of the bottom VBE at various levels of inter‐story drift. Considering both the tension field action of the infill panel and the sway action of the boundary frame, this study develops a simplified method to compute the flexural and shear demands in the bottom VBE. Based on the superposition method, this approach considers various plastic hinge forming locations at different levels of inter‐story drift. One of the key performance‐based design objectives is to ensure that the top ends of the bottom VBEs remain elastic when the SPSWs are subjected to the maximum considered earthquake. This paper presents the comprehensive design procedures for the bottom VBE. Furthermore, this study conducted cyclic performance evaluation tests of three full‐scale two‐story SPSWs at the Taiwan National Center for Research on Earthquake Engineering in 2011 to validate the effectiveness of the proposed design methods. The experimental program, cyclic inelastic responses of the SPSWs and bottom VBEs, and numerical simulations are presented in Part 2. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Numerical modelling of aeolian erosion over a surface with non‐uniformly distributed roughness elements 下载免费PDF全文
The present study is focused on the analysis of the mean wall friction velocity on a surface including roughness elements exposed to a turbulent boundary layer. These roughness elements represent non‐erodible particles over an erodible surface of an agglomeration of granular material on industrial sites. A first study has proposed a formulation that describes the evolution of the friction velocity as a function of geometrical parameters and cover rate with different uniform roughness distributions. The present simulations deal with non‐uniform distributions of particles with a random sampling of diameters, heights, positions and arrangements. The evolution (relative to geometrical parameters of the roughness elements) of the friction velocity for several non‐uniform distributions of roughness elements was analysed by the equation proposed in the literature and compared to the results obtained with the numerical simulations. This comparison showed very good agreement. Thus, the formulation developed for uniform particles was found also to be valid for a larger spectrum of particles noted on industrial sites. The present work aims also to investigate in detail the fluid mechanics over several roughness particles. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Reinforced concrete (RC) precast shear walls are extensively applied in practical engineering, owing to their fast construction speed. However, because of the transport conditions, RC precast shear walls have to be separated into small wall segments during the factory prefabrication procedure before being assembled on site. Typically, wet-type jointing methods are adopted to link the segments, which is time-consuming and results in unreliable post-pouring area strength. To overcome this problem, the novel scheme of the steel shear key (SSK) featuring steel shear panels and combined fillet and plug welding is proposed. Three RC precast shear wall specimens with different linking strength, termed as weakened SSK wall, standard SSK wall, and strengthened SSK wall, respectively, and an integrated shear wall specimen were designed. Quasi-static cyclic loading was applied to investigate the specimens' dynamic properties. The test results suggest the prefabricated wall segments equipped with SSKs showed reliable stiffness and bearing capacity and were improved in energy dissipation ability, compared with conventional shear walls. As the shear stiffness and number of equipped SSKs increased, the specimens exhibited higher strength, but their ductility and energy dissipation were slightly decreased. Most importantly, the standard SSK wall specimen could achieve satisfactory bearing capacity and deformability and is thus recommended for precast building structures. Finite element method (FEM) models were established to validate the test results, and parametric study analysis was conducted based on the coupling ratio of the SSK walls. Finally, an appropriate coupling ratio range is recommended for practical engineering applications. 相似文献