考虑基坑开挖影响的群桩基础竖向承载性状数值分析     

王成华  刘庆晨 《岩土力学》2012,33(6):1851-1856

对土体采用Mohr-Coulomb弹塑性本构模型,用接触面单元模拟桩-土相互作用,利用ABAQUS建立桩筏基础--地基--基坑开挖三维有限元分析模型。对基坑开挖影响下的群桩基础竖向承载性状进行了分析,讨论了桩顶反力分布、桩身轴力、桩侧摩阻力以及开挖引起的桩身水平位移及其弯矩的变化规律,并进行了考虑基坑开挖与不考虑基坑开挖的群桩基础竖向承载性状的对比分析。通过研究,取得了基坑开挖对高层建筑桩筏基础影响的基本认识,这些认识对于改进桩筏基础设计理论有一定的参考意义。  相似文献   

Integral equation method for analysis of piled rafts with dissimilar piles under vertical loading     

Fayun Liang  Longzhu Chen  Jie Han 《Computers and Geotechnics》2009

In a piled raft, the length and arrangement of piles has a significant effect on the stresses and deflections of the raft. The use of piles with different dimensions and properties below a raft is an innovative concept and can optimize the design of a piled raft. In this study, an integral equation method with a fictitious pile model was adopted to analyze the piled raft foundation with dissimilar piles. The Fredholm integral equations of the second kind were obtained for this problem. The loads shared by piles and subsoil, the load transfer, and the settlement of the piled raft were obtained using numerical calculation. The results from the present method were compared with those in the literature. An optimization technique was introduced to design piled rafts with dissimilar piles. The stiffening effect of piles on the surrounding soil is also discussed as compared the conventional interaction factor approach.  相似文献   

桩箱（筏）基础刚度计算的改进及其应用     

阳吉宝  任臻 《岩土力学》1997,18(2):35-39

软土地区，桩箱（筏）基础是高层尤其是超高层建筑的首选基础型式。在桩箱（筏）基础刚度计算研究基础上，对桩箱（筏）基础优化设计进行探讨，力求将桩箱（筏）基础研究上升到优化设计的新高度。  相似文献   

西秦岭白依沟群沉积环境分析     

闵永明  文锦明 《矿物岩石》1991,11(1):51-58

白依沟群是西秦岭地区迄今发现的最古老地层,厘定为震旦系下统,是一套浅变质水携火山碎屑岩—陆源碎屑岩建造。依据其沉积环境的差异和岩石组合,划分为上、中、下三段。通过笔者研究,认为是大陆山间河流出口处近源冲积扇体中形成的辫状河体系,为主河道—河道心滩—洪泛平原与湖泊等环境的沉积产物。  相似文献   

Laboratory model tests about the sand embankment supported by piles with a cap beam     

Zhen-Dong Cui  Qiang Yuan  Jia-Qiang Yang 《Geomechanics and Geoengineering》2018,13(1):64-76

Piled embankment is widely used in soft soil areas. Most researches focused on effects of embankment height-net pile spacing ratios and equal settlement plane; there are limited publications paying attention to the shape of slip surfaces occurring in the embankment. In some extreme conditions, such as the ground being quite soft or embankment height needed to be restricted, to reduce the differential settlement and lateral displacement, piles are usually installed in several rows and cap beams or isolated caps are placed on the heads of piles. In this paper, five laboratory tests were carried out to investigate the effect of embankment height on the slip surfaces and stress exerted on the subsoil. Based on the observation of the slip surface’s shape within the embankment fill, a new calculation model is proposed to predict the stress exerted on the subsoil. In comparison with the experimental results, the accuracy of this new method is verified. From the perspective of reducing the differential settlement and cost savings, the embankment height is about four times net pile spacing according to this calculation model, since continuing to increase the embankment will not make an obvious difference to the reduction of soil stress exerted on the subsoil.  相似文献   

Dynamics of Submersible Mussel Rafts in Waves and Current     

王欣欣  M. Robinson SWIFT  Tobias DEWHURST  Igor TSUKROV  Barbaros CELIKKOL  Carter NEWELL 《海洋工程》2015,29(3):431-444

To investigate the dynamics of submersible mussel rafts, the finite element program Aqua-FE?, developed by the University of New Hampshire (UNH), was applied to rafts moored at the surface and submerged. The submerged configuration is used to reduce wave forcing and to avoid contact with floating ice during winters in northern waters. Each raft consists of three pontoons connected by a grid framework. Rafts are intended to support densely spaced mussel ropes hung from the framework. When submerged, the pontoons are flooded, and the raft is held vertically by floats attached by lines. The computer models were developed in Aqua-FE? to simulate the effects of waves and current. They were validated by comparison with wave tank results by use of a 1/10 scale raft physical model. Comparisons showed good agreement for the important heave (vertical) and pitch (rotational) motions, though there was a tendency towards conservative results for wave and current drag. Full-scale simulations of surface and submerged single raft and two rafts connected in tandem were performed. Submerged raft wave response was found to be reduced relative to that at the surface for both the single and two-raft configurations. In particular, the vertical motion of mussel rope connection points was significantly reduced by submergence, resulting in reduced potential for mussel drop-off. For example, the maximum vertical velocities of mussel rope attachment points in the submerged two raft case were 7%?20% of the corresponding velocities when at the surface.  相似文献   

群桩与筏板的竖向动力相互作用研究     

徐新生  燕彬 《岩土力学》2009,30(1):281-284

对沿深度离散形成一系列均质的土层,应用传递矩阵法推导出单桩的动力阻抗。借助推求的桩-桩动力相互作用因子,研究承台板与群桩的竖向动力相互作用,通常假设承台板是刚性的,并充分考虑了承台板具有一定的刚度、可以变形的柔性承台板,提出承台板-群桩动力相互作用模型,然后推出其动力相互作用方程。通过算例说明了承台板的刚度对承台板的动力作用是有影响的。研究结果表明,振动频率越低,柔性承台板的振幅与刚性承台板的振幅相差越大;随着频率的增大,二者差别也减小,并逐渐趋于相等。  相似文献   

考虑上部结构的桩筏基础非线性共同作用分析     

张鹤年  宰金珉 《工程地质学报》2006,14(4):557-563

当前虽然已有考虑桩筏非线性的设计,但仍无人在此基础上,考虑上部结构。因此考虑上部结构,进一步认识其与桩筏基础非线性共同作用机理,优化桩筏基础设计,具有重要的现实意义。本文以子结构法凝聚上部结构的荷载及刚度,以平面壳体单元模拟筏板,按有限层法模拟桩土之间的弹性相互作用,用广义剪切位移法模拟桩的非线性工作性状,建立了一种考虑上部结构共同作用的桩筏基础非线性分析方法,并编制了分析程序。通过实例分析,探讨了上部结构与桩筏基础非线性共同作用的机理,研究了合理布桩方式,探讨了以差异沉降为目标的优化设计的可能途径。  相似文献   

桩承式围堤对邻近桥梁桩基的影响分析     

吴兴龙  吴雅峰  梁民阳  李树巍 《岩土力学》2008,29(7):2004-2008

桩承式围堤是将上部围堤或堆载荷重通过桩筏基础传递到深层较硬的土层,以减少由于围堤或堆载对邻近桩基产生负摩阻力和侧向推力的一种围堤式构筑物。采用基于Mindlin应力解的桩伐基础简化分析方法、弹性和弹塑性三维数值模拟了嘉兴港海盐港区围堤对杭州湾跨海大桥产生的负摩阻力和侧向推力。通过上述3种方法的分析比较,结果表明,采用的简化分析方法与弹性和弹塑性三维数值模拟结果吻合较好,可作为桩承式围堤结构基础的分析和设计方法。  相似文献   

鼠尾藻劈叉筏式养殖试验   总被引：7，自引：0，他引：7  

原永党  张少华  孙爱凤  刘海燕 《海洋湖沼通报》2006,(2):125-128

2004~2005年,在山东省威海海区进行了鼠尾藻劈叉筏式养殖试验。2004年试验持续123d,试养鼠尾藻2×667m2,平均株长由5.5 cm生长至79.1 cm,鲜藻产量2.52 kg/m2;2005年试验持续70d,试养鼠尾藻3×667m2,平均株长由13.0 cm生长至73.7 cm,鲜藻产量为2.88 kg/m2。试验结果表明鼠尾藻的劈叉式筏式养殖是可行的。  相似文献