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201.
202.
通过室内模型试验,对黄土地基中大直径超长群桩基础的承载-沉降关系、承台下土体附加应力的分布及发展、桩土承载情况以及不同位置桩的受力特性分别进行了研究。结果表明:黄土地基中大直径超长群桩基础荷载-沉降曲线呈缓变型且没有明显拐点,故群桩基础的极限承载力应综合沉降-时间对数s-lgt曲线和荷载-沉降Q-s曲线来确定。承台下土体附加应力分布为边缘大中心小。不同位置的桩承载性能不同,总体上是角桩(6#桩)最大,边桩(5#桩)次之,中心桩(1#桩)最小;同时各桩的桩侧摩阻力及桩身轴力沿桩长的变化也有所不同。 相似文献
203.
The linearized problems on the stability of a circular sandwich ring of symmetric structure under an axially symmetric temperature field inhomogeneous across the core thickness are stated and analytical solutions to them are given. The first problem deals with the mixed flexural buckling form (BF) of the ring as a whole, realized as a result of buckling in one of the load-carrying layers due to formation of precritical pressure stresses in the layer. The second problem considers purely shear BFs when one load-carrying layer is rotated relative to the other. The deformation processes for the load-carrying layers are described by the Kirchhoff-Love model, and for the core of arbitrary thickness - by two models, namely by the equations of the plane problem of elasticity theory and by the model of a transversely soft layer of arbitrary thickness (the same equations simplified by the assumption of zero circumferential normal stresses). Within the frames of the first model adopted for the core, the shear BF is theoretically possible but practically unrealizable, since the mixed flexural BF arises earlier than the shear BF. 相似文献
204.
弹性地基板的弯曲问题,尤其是自由边板,一直是学者和工程师们所十分关切的问题。本文用无单元法研究双参数弹性地基板的弯曲问题,由最小二乘法和变分原理导出了双参数弹性地基板的无单元法刚度短阵,编制相应的无单元法计算程序,并给出计算实例。结果表明本方法精度良好,可求出任意荷载作用下板中任一点的挠度、转角、弯矩和扭矩,且有广泛的工程应用前景。 相似文献
205.
球面各向同性球体内的动态热应力集中 总被引:1,自引:0,他引:1
利用有限克尔变换得到了求面各向同笥球体的热冲击作用下的动态热应力解析表达式。从表达式中,可以看出球中向同性球体的动态热应力集中现象明显不同于各向同性球体。另外,所描述的动态热应力集中现象与文献「1,3」也有一定的区别。 相似文献
206.
A direct domain/boundary element method (D/BEM) for the dynamicanalysis of elastoplastic thick plates resting on Winkler-typefoundation is presented. The formulation presented includes the effectsof shear deformation and rotatory inertia following Reissner–Mindlin'sdeformation theory assumption. The method employs the elastostaticfundamental solution of the problem resulting in both boundary anddomain integrals due to inertia, plasticity and foundation pressureterms. By discretizing the integral equations and integrating theresulting matrix equation of motion by an explicit time integrationscheme the history of the plate dynamic response can be obtained.Applications are shown for impacted elastoplastic Reissner–Mindlinplates with smooth boundaries on several different foundations. 相似文献
207.
具有弹性夹层的文克勒地基上双层叠合梁的解 总被引:3,自引:0,他引:3
将双层叠合梁之间的接触状况拟合为一符合 Goodman假设的弹性夹层 ,导出了Winkler弹性地基上双层叠合梁的微分方程组及其解析解。通过引入“广义夹层反应模量”计入了夹层水平和竖向反力引起的梁截面的剪切和拉压形变效应 ,它有效地提高了计算精度 ,尤其是在双层梁结构有间断的场合。 相似文献
208.
Marcel Lesieur P. Comte Y. Dubief E. Lamballais O. Métais S. Ossia 《Flow, Turbulence and Combustion》2000,63(1-4):247-267
We first recall the EDQNM two-point closure approach of three-dimensional isotropic turbulence. It allows in particular prediction
of the infrared kinetic-energy dynamics (with ak
4 backscatter) and the associated time-decay law of kinetic-energy, useful in particular for one-point closure modelling. Afterwards,
we show how the spectral eddy viscosity concept may be used for large-eddy simulations: we introduce the plateau-peak model
and the spectral-dynamic models. They are applied to decaying isotropic turbulence, and allow recovery of the EDQNM infrared
energy dynamics. Anew infrared k
2 law for the pressure spectrum, predicted by the closure, is also well verified.
Assuming that subgrid scales are not too far from isotropy, the spectral-dynamic model is applied to the channel flow at h
+= 390, with statistics in very good agreement with DNS, while reducing considerably the computational time. We study with
the aid of DNS and LES the case of the channel rotating about an axis of spanwise direction. The calculations allow to recover
the universal linear behaviour of the mean velocity profile, with a local Rossby number equal to −1.
We present also LES (using the Grenoble Filtered Structure-Function Model), of a turbulent boundary layer passing over a cavity.
Finally, we make some remarks on the future of LES for industrial applications.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
209.
三维各向同性谐振子的超对称量子力学体系 总被引:3,自引:3,他引:0
利用三维各向同性谐振子的中升、降算子,分别构造不同的超对称量子力学体系,并研究了它们的性质。 相似文献
210.