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Sayed Shaaban 《Journal of Terramechanics》1984,21(3):253-260
Vehicle wheels apply on the soil loads of variable inclination. Increasing load inclination causes a decrease in the soil bearing capacity and produces more sinkage of wheels. In the present study the change of soil bearing capacity with load inclination is investigated. Plate-sinkage tests in which load inclination to the vertical is varied from zero to thirty degrees are elaborated. A modification of Bekker's bearing capacity equation to account for load inclination is proposed, and a comparison of experimental and predicted bearing capacity curves is shown. 相似文献
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微尺度气体滑动轴承的Monte Carlo模拟与性能分析 总被引:2,自引:2,他引:0
改进了直接模拟Monte Carlo (DSMC)方法并模拟研究了轴承构型、滑动速度、壁温及环境压力对微气体滑动轴承内部压力分布及承载能力的影响.结果表明:轴承的几何构型和滑动速度对轴承的性能影响很大,对于相同长度的轴承,气体的峰值压力与轴承的承载能力随轴承出口尺寸的减小和滑动速度的增大而增大;当轴承的几何形状和滑动速度固定时,通道壁温和环境压力是影响轴承性能的重要因素,壁温越高,轴承的承载能力越强;环境压力不同,轴承性能亦有所不同. 相似文献
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永磁向心轴承承载能力与刚度的计算 总被引:17,自引:1,他引:17
目前,尽管磁浮轴承技术的研究与开发应用已经受到国内外学者的广泛重视,但在永磁向心轴承承载能力的研究方面,却还存在着两个尚待解决的问题:一是将环形磁体作为无限长条形磁体处理,二是只能对轴承承载能力进行估算。针对这种情况,根据等效磁荷理论,在圆环状态下对轴向控制的永磁向心轴承的承载能力和刚度进行了研究,建立了永磁向心轴承承载能力数学模型,并对其计算结果作了试验验证,同时还提出了利用刚度系数建立的可供工程设计应用的永磁轴承承载能力和刚度的计算公式。结果表明,承载能力的计算值与实测值相当吻合;在偏心距的实际应用范围内,永磁向心轴承的径向刚度是个常量;内外磁环的轴向位移对磁轴承的承载能力和刚度都有明显的影响.因此,为了最大限度地提高这种轴承的承载能力和刚度,就要在设计其结构的过程中注意尽力保证内外磁环轴向对齐。 相似文献
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针对CFD仿真方法效率低下的状况,提出利用阻抗法来提升气浮支承承载性能的计算速度. 以矩形截面均压槽气浮支承为研究对象,研究了当均压槽高度、角度、数量、半径和供气压力变化对气浮支承承载性能的影响. 结果表明:与CFD仿真方法相比,阻抗法在保证计算结果精度的前提下可提高气浮支承承载力的计算速度. 当均压槽高度、角度、数量、半径和供气压力增大时,阻抗比会增加,气浮支承的承载力和刚度峰值对应的阻抗比也会增加. 当气膜厚度增加时,阻抗比会增加,但承载力会相应地减小. 本文作者通过阻抗法推导了气浮支承承载力简化计算公式,解决了气浮支承在均压槽方向上简化计算的难点,并为阻抗法在均压槽中的研究与应用提供了理论依据. 相似文献
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采用我国混凝土规范GB50010-2002规定的混凝土应力一应变关系,考虑混凝土强度、构件长细比及混凝土徐变,从构件的非线性理论出发对钢筋混凝土轴心受压构件的承载力进行了研究,给出了混凝土构件临界状态时的构件边缘应变和纵向弯曲系数的计算公式。研究表明,徐变对轴心受压构件的承载力有很大影响。当不考虑混凝土徐变时,按本文公... 相似文献
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在大型有限差分软件FLAC3D平台上进行二次开发,利用内嵌FISH语言编程,对盾构隧道动态施工过程中上部基桩承载力的影响进行数值仿真模拟,模型考虑盾构前方土仓压力、盾尾同步注浆、注浆凝结和未凝结两种状态以及衬砌管片施加等施工参数。从桩侧摩阻力、桩端阻力等方面对盾构开挖过程中上部桩基承载力进行分析,以及土仓压力变化对承载力影响。研究结果表明:随着隧道开挖,桩侧摩阻力、桩端阻力发生复杂变化,桩底部出现负摩擦力,桩端轴力为拉力,对基桩竖向极限承载力有一定的影响;并且开挖面距桩轴线不同位置,土仓压力对基桩竖向极限承载力影响不同。 相似文献
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近年来的研究发现固液界面的滑移可以减小表面摩擦,但也会造成流体动力效应下降甚至消失.本文提出了复合表面滑动轴承的概念,轴套表面由具有不同吸附和滑移特性的复合表面组成,发现复合表面轴承比普通轴承有许多优点.通过改变轴套表面的滑移特性可以改变和优化轴承的各种性能,例如摩擦系数、承载力、润滑剂流量、承载角等.数值解表明,在轴承高压区改变轴套表面滑移特性,轴承的整体性能会有大幅度提高.例如,本文给出的初步优化设计方案使得摩擦系数降低50%以上,同时承载力可提高20%,并且承载角可以降低33%.本文提出的设计理念不但可用于设计出具有更优异特性的径向滑动轴承,而且可以设计出具有复合表面的轴向滑动轴承或滑块轴承.复合表面滑动轴承在降低轴承摩擦、提高承载能力方面有很大的空间可以探索. 相似文献
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A slip-line field solution is presented for the ultimate bearing capacity of the pipeline on a purely-cohesive clay soil, taking into account of circular configuration of the pipe, the pipe embedment, and the pipe-soil interfacial cohesion. The derived bearing capacity factors for a smooth rigid pipe may degenerate into those for the conventional rectangular-shaped strip footing while the pipe embedment approaches zero. Parametric studies indicate that, the pipe-soil interfacial properties have much influence on the bearing capacity for the pipe foundation on clayedy soils. 相似文献
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This paper describes a technique for computing lower bound limit bearing capacity of rectangular surface footings. A perfectly rigid plastic model is adopted to describe the property of soil materials. The bearing capacity of footing is regarded as the objective function in this method, subject to the stress boundary condition, stress discontinuity equilibrium condition, stress equilibrium condition and yield condition. By solving a non-linear optimization problem, i.e., searching the maximum value of objective function, the bearing capacity of smooth surface rectangular footing and the corresponding 3D stress field are obtained. 相似文献
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地基承载力的试验研究 总被引:1,自引:0,他引:1
进行地基承载力的试验研究, 对于充分利用和挖掘地基潜力、合理选择地基持力层、提高勘察工作质量、促进岩土工程勘察技术的发展具有重要的现实意义。本文结合唐山钢铁公司第二炼铁厂 2 5 6 0m3 高炉勘察实例, 系统介绍了地基承载力的试验研究过程, 并应用了-种有推广价值的试验技术—室内模拟载荷试验。 相似文献
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Bearing capacity of the unstructured terrain considering the effects of the wheel geometry and soil mechanic properties is analyzed in this paper. Two-dimensional pressure-sinkage simulations are conducted to evaluate the degrees of similarity between the flat plate and wheel in terms of their ultimate bearing characteristics of Terzaghi theory. The results show that these degrees of similarity are mainly reflected in the soil in-depth direction and the corresponding failure behaviors. Based on the approximation of the ultimate bearing capacity between the wheel and flat plate, a piecewise bearing capacity evaluation method with the effects of the soil mechanic properties and three-dimensional wheel geometry is proposed. The pressure-sinkage values of the proposed model show a satisfactory agreement with the experimental ones. The proposed model performs better than the semi-empirical models, as it considers more soil bearing features and needs less fitting parameters to assess the unstructured terrain. 相似文献
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Using the method of characteristics,the bearing capacity for a strip footing is analyzed.The method of characteristics leads to an exact true limit load when the calculations of the three terms in the bearing capacity formula are consistent with one collapse mechanism and the soil satisfies the associated flow rule.At the same time,the method of characteristics avoids the assumption of arbitrary slip surfaces,and produces zones within which equilibrium and plastic yield are simultaneously satisfied for given boundary stresses.The exact solution without superposition approximation can still be expressed by Terzaghi's equation of bearing capacity,in which the bearing capacity factor N γλ is dependent on the dimensionless parameter λ and the friction angle φ.The influence of groundwater on the bearing capacity of the shallow strip footing is considered,which indicates that when the groundwater effect is taken into account,the error induced by the superposition approximation can be reduced as compared with dry soil condition.The results are presented in the form of charts which give the modified value(Nwγλc /Nγλc) of bearing capacity factor.Finally,an approximated analytical expression,which provides results in close agreement with those obtained by numerical analysis in this paper,has been suggested for practical application purposes. 相似文献
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泊松比对钢管混凝土拱桥极限承载力的影响 总被引:1,自引:0,他引:1
主要研究在几何和材料双非线性影响下,分析大跨度钢管混凝土拱桥钢管内混凝土泊松比变化对桥梁极限承载力的影响.。以某桥为背景,利用ansys程序进行三维有限元仿真分析,在考虑混凝土泊松比变化情况下,逐步改变核心混凝土泊松比直至结构破坏,并与不考虑混凝土泊松比变化的情况相比较,以考察核心混凝土泊松比变化对桥梁极限承载力影响程度,得出在对拱桥的极限承载力分析时,考虑钢管对核心混凝土的套箍作用,可使极限承载力比不考虑混凝土泊松比变化时的计算值高出10%。 相似文献