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61.
In this study, a variational approach to the settlement analysis of an axially loaded pier embedded in a multi-layered soil
profile is presented. In this method, the soil profile and the embedded pier are divided into a number of sub-layers according
to the actual number of soil layers observed in the field. The displacement shape function of each soil layer is given as
a product of an exponential equation along the pier depth and the Bessel's solution in the radial direction. The displacement
relationship among the layers can be derived through the transformation matrices. One of the major features of this method
is that the total number of pier elements is the same as that of soil sub-layers. All the field components, such as the displacement,
stress, and strain in the soil, can be calculated by closed-form solutions except that the only unknown variable is the value
β which can be determined by iteration techniques. Comparisons were made with the results of finite element analysis and the
field observation in pile-loaded tests. 相似文献
62.
The response of an intrinsic Ge detector in energy‐dispersive diffraction measurements with synchrotron radiation is studied with model calculations and diffraction from perfect Si single‐crystal samples. The high intensity and time‐structure of the synchrotron radiation beam leads to pile‐up of the output pulses, and the energy distribution of the pile‐up pulses is characteristic of the fill pattern of the storage ring. The pile‐up distribution has a single peak and long tail when the interval of the radiation bunches is small, as in the uniform fill pattern, but there are many pile‐up peaks when the bunch distance is a sizable fraction of the length of the shaping amplifier output pulse. A model for the detecting chain response is used to resolve the diffraction spectrum from a perfect Si crystal wafer in the symmetrical Laue case. In the 16‐bunch fill pattern of the ESRF storage ring the spectrum includes a large number of `extra reflections' owing to pile‐up, and the model parameters are refined by a fit to the observed energy spectrum. The model is used to correct for the effects of pile‐up in a measurement with the 1/3 fill pattern of the storage ring. Si reflections (2h,2h,0) are resolved up to h = 7. The pile‐up corrections are very large, but a perfect agreement with the integrated intensities calculated from dynamical diffraction theory is achieved after the corrections. The result also demonstrates the convergence of kinematical and dynamical theories at the limit where the extinction length is much larger than the effective thickness of the perfect crystal. The model is applied to powder diffraction using different fill patterns in simulations of the diffraction pattern, and it is demonstrated that the regularly spaced pile‐up peaks might be misinterpreted to arise from superlattices or phase transitions. The use of energy‐dispersive diffraction in strain mapping in polycrystalline materials is discussed, and it is shown that low count rates but still good statistical accuracy are needed for reliable results. 相似文献
63.
从深基坑护壁桩桩身弯矩分析桩侧土压力 总被引:8,自引:0,他引:8
根据某高层建筑深基坑护壁桩从实测钢筋应力求得的桩身变矩,用数值分析的方法,对桩侧土压力的分布和大小进行了反分析,所得结果与经典土压力理论有显差别,中用土拱的概念对桩侧土压力的分布进行了解释,并给出了桩侧土压力建议图式。 相似文献
64.
基于回传射线矩阵法,求得单位脉冲作用下成层土中半埋人完整桩的桩顶速度导纳和相位,然后利用Fourier逆变换和卷积定理求得瞬态半正弦激振力作用下的桩顶时域速度响应.比较均匀地基、上软下硬(上硬下软)两层地基、软夹层(硬夹层)三层地基的桩顶速度响应,进一步分析土体剪切模量、上覆土层厚度、软(硬)夹层厚度对桩顶速度导纳、相位和反射波的影响.结果表明:土体剪切模量及土层厚度对桩顶速度导纳、相位以及反射波影响很大. 相似文献
65.
Five isostructural tetranuclear lanthanide complexes with the general formula [Ln4(teaH2)2(teaH)2(NO3)6] · 2CH3OH [Ln3+ = Dy3+ ( 1 ), Tb3+ ( 2 ), Ho3+ ( 3 ), Er3+ ( 4 ), and Gd3+ ( 5 )] were successfully synthesized by the reaction of various lanthanide nitrate and triethanolamine (teaH3) ligand. Single crystal X-ray analyses reveal the eight-coordinate Ln3+ centers adopt a slightly distorted triangular dodecahedron geometry and nine-coordinate Ln3+ ions own an approximately capped square antiprism environment in similar zigzag Ln4 core. Magnetic studies demonstrate the presence of anitferromagnetic interactions between Ln3+ centers without obvious SMM behavior. 相似文献
66.
单桩动力特性影响因素分析 总被引:3,自引:1,他引:3
本文通过对复合平面应变近似法的改进,导出单桩桩基的动力复刚度,分析影响桩基动力刚度和阻尼的因素,得到一些结论,为桩基优化设计提供依据 相似文献
67.
利用Mindlin竖向附加应力公式,通过积分得到地基内矩形面积上三角形分布荷载作用下角点下竖向附加应力解析式,并通过对地基内矩形面积上均布和三角形分布载荷作用下角点下竖向附加应力公式关于深度进行积分,得到了计算角点下竖附加应力面积的解析式,根据解析式制表格,可供运用应力面积法进行群桩实体基础等的最终沉降计算时查用。 相似文献
68.
69.
70.
船舶与海洋平台撞击的荷载模拟 总被引:3,自引:0,他引:3
以某导管架结构的X斜撑在导管架安装阶段受到大吨位起重铺管船撞击后的损伤检测结果为依据。对碰撞过程进行了数值模拟,按照构件模型从简单到复杂的模拟思路得到了船舶对海洋平台结构的撞击力。建立了船舶与海洋平台碰撞系统的力学模型,对导管架平台受损构件进行了等效静力强度计算分析。为了考虑在船舶冲撞下的整体平台结构动力效应的影响,在分析时考虑了碰撞过程的水动力效应,桩-土-平台结构的相互作用,采用非线性弹簧来模拟受损构件局部凹陷损伤,在船舶以不同的速度与平台发生碰撞的情况下,模拟出平台受撞击构件的永久凹陷变形与碰撞接触时间的曲线.反演分析计算了船舶对平台结构碰撞的最大撞击力。为确定受到撞击后导管架平台结构构件和管节点的损伤程度,提出合理可行的修理加固方案提供了分析依据。 相似文献