共查询到19条相似文献，搜索用时 343 毫秒
1.
2.
基于Laplace变换,对层状地基中桩土横向振动阻抗计算问题进行了研究。考虑土层天然分层的特性及桩顶轴向力的参与作用,结合频域内桩-土动力文克尔理论,采用传递矩阵法并通过拉普拉斯变换,将振动微分方程变成代数方程以求解桩的横向振动响应参数,并导出了单桩横向振动阻抗。基于所得解,进一步计算出桩-土-桩水平动力相互作用因子。通过实例分析对比,验证其有效性和可行性。该方法计算工作量小,易于理解,计算结果与已有结果具有良好的一致性,并能保证解的连续性,对桩-土动力相互作用的研究具有一定的实用意义。 相似文献
3.
Dobry和Gazetas分析群桩振动特性的理论是将土体视为单相介质提出的,对于饱和土中桩-桩相互作用和群桩振动是否适用有待验证。将土体视为液固两相多孔介质,运用Novak薄层法和引入势函数的方法,求解了饱和土层的水平动力阻抗和自由场水平位移衰减函数,并在初参数法的基础上求解了桩-桩水平动力相互作用因子,运用基于动力相互作用因子的叠加原理对饱和土中群桩的水平振动进行了分析,并以3×3桩为例对群桩动力阻抗的主要影响参数进行了分析。提供了一种分析饱和土中桩-桩动力相互作用和群桩动力阻抗的新方法。 相似文献
4.
《岩土力学》2017,(10):2817-2825
考虑桩周饱和土和桩芯饱和土的三维波动效应研究了饱和土中管桩群桩的水平振动,得到了管桩群桩的水平动力阻抗。将桩周土和桩芯土视为两相饱和土,并利用多孔介质理论来描述其力学特性。运用数学物理手段求得了桩周饱和土和桩芯饱和土的水平动力阻抗。运用波的传播理论和叠加原理,同时考虑边界条件和三角函数的正交性,求得了管桩群桩中任一根管桩的水平作用力。考虑刚性承台处管桩桩顶位移协调条件和桩顶水平作用力平衡条件,得到了饱和土中管桩群桩的水平动力阻抗。以2×2管桩群桩为例分析和讨论了有关物理参量对饱和土中管桩群桩水平振动特性的影响。研究结果表明:实芯群桩与管桩群桩的水平动力阻抗都存在一定的差异,频率较小时需要考虑桩芯饱和土与桩周饱和土性质的差异对管桩水平动力阻抗的影响,管桩长径比和管桩壁厚对饱和土中管桩群桩水平振动的影响较大,在实际工程设计中需要重点考虑桩身尺寸。 相似文献
5.
6.
分层土中群桩水平动力阻抗的改进计算 总被引：1，自引：0，他引：1
采用动力Winkler地基梁模型,建立了主动桩和被动桩的简化解析运动方程,考虑地基土的分层特性、桩身剪切变形和转动惯量,提出了计算分层地基中单桩和群桩动力阻抗的改进计算方法,并与已有文献的计算结果进行了对比,结果表明：改进方法的计算结果与现场实测更接近。在低频段,改进方法的计算结果与已有文献结果较一致,但随着桩身剪切模量的减小,两者差异增大。差异主要是由考虑桩身剪切变形和转动惯量引起的,且前者影响较大,在低频段差异亦十分明显,而后者影响较小,在群桩阻抗峰值区域和高频段差异明显,需考虑桩身转动惯量的影响。 相似文献
7.
以动力文克尔地基梁模型为基本理论,在改进了Gazetas均质土中的桩-土-桩相互作用三步法计算模式的基础上,运用分层传递技术,导出了层状地基中群桩在轴、横多向受力条件下的力与位移动力相互关系的显示表达,提出了桩顶谐振作用条件下计算层状介质中动力相互作用因子的新方法,以相对简明的方式阐述了桩顶轴力对群桩水平动力效应的影响,并以此来寻求频域动载下的基桩变位及其内力规律,较为全面地揭示群桩振动特性。 相似文献
8.
刚性桩复合地基应力及沉降计算 总被引：1，自引：1，他引：1
通过分析桩-土-垫层相互作用,讨论了刚性桩复合地基的沉降特性.借助半无限弹性空间中的Geddes解和Mindlin解,求出考虑刺入变形的复合地基中的竖向附加应力,从而得出刚性桩复合地基的一种沉降计算方法. 相似文献
9.
传统的抗震设计都是基于刚性地基的假设,然而在实际中,地基会发生变形致使上部结构的动力特性改变。本文结合工程实例,建立非线性有限元桩-土模型和土弹簧桩-土模型桩,用ANSYS建立了非线性有限元实体桩和土弹簧桩的房屋结构模型研究地震作用下结构在考虑桩-土-结构动力相互作用时的动力特性及其地震响应。 相似文献
10.
桩筏基础相互作用分析 总被引：1，自引：0，他引：1
提出了考虑土-桩-筏相互作用的迭代分析方法,可获得筏板的内力和桩身轴力等.考虑了桩筏基础下群桩效应作用的群桩桩顶反力分布、群桩桩端力分布及桩与桩相互作用等问题,使得计算的群桩单桩刚度较合理.同时,具有能考虑土的非线性、成层地基及利用单桩静载试验成果反演分析所得参数运用于群桩分析等特点.采用的8节点等参板单元可适用于分析平面不规则形状及变厚度的薄筏板和厚筏板.用笔者提出的方法对桩筏基础实例进行了分析,研究了桩长对该桩筏基础相互作用的影响,并与实测成果及其他学者研究成果进行了对比,表明了该方法能较合理地分析桩筏基础相互作用. 相似文献
11.
It is common in the analysis of piles under lateral loads to use a model of a beam on elastic foundation, or a finite element model with the pile represented by a one dimensional beam–column with its axis coinciding with the central line of the finite element mesh. In both cases the lateral stiffness of the pile itself, as a structural element, is a function of the product of its Young’s modulus of elasticity by the moment of inertia of the cross section (EI). For solid piles the moment of inertia is directly related to the radius but this is not the case when dealing with hollow piles where the value of the radius corresponding to a given moment of inertia is not unique. Both of the above models ignore the effect of the value of the radius of the soil cavity occupied by the pile. In this work a more accurate model of the pile with the soil around it represented. A consistent boundary matrix valid for static and dynamic analyses is used to evaluate the accuracy of the results provided by the model of a beam on elastic foundation. In addition, a 1D model of the pile is analyzed with finite elements for the soil. This analysis considers a fixed value of the product EI, but a variable radius in order to illustrate the importance of the radial dimension. Results are obtained for a pile fixed at the bottom, but long enough so that the top boundary conditions do not affect the results and for a shorter floating pile were the shear and moment at the bottom resulting from the underlying soil would not be zero. For the beam on elastic foundation model, the top of the pile was assumed to be fixed. 相似文献
12.
A series of centrifuge shaking table model tests are conducted on 4?×?4 pile groups in liquefiable ground in this study, achieving horizontal–vertical bidirectional shaking in centrifuge tests on piles for the first time. The dynamic distribution of forces on piles within the pile groups is analysed, showing the internal piles to be subjected to greater bending moment compared with external piles, the mechanism of which is discussed. The roles of superstructure–pile inertial interaction and soil–pile kinematic interaction in the seismic response of the piles within the pile groups are investigated through cross-correlation analysis between pile bending moment, soil displacement, and structure acceleration time histories and by comparing the test results on pile groups with and without superstructures. Soil–pile kinematic interaction is shown to have a dominant effect on the seismic response of pile groups in liquefiable ground. Comparison of the pile response in two tests with and without vertical input ground motion shows that the vertical ground motion does not significantly influence the pile bending moment in liquefiable ground, as the dynamic vertical total stress increment is mainly carried by the excess pore water pressure. The influence of previous liquefaction history during a sequence of seismic events is also analysed, suggesting that liquefaction history could in certain cases lead to an increase in liquefaction susceptibility of sand and also an increase in dynamic forces on the piles. 相似文献
13.
Hasan Ghasemzadeh Mohsen Tarzaban Mohammad Mahdi Hajitaheriha 《Geotechnical and Geological Engineering》2018,36(4):2189-2215
Battered piles are usually used to counteract lateral forces in a pile group. As there is little spacing between piles, they are affected by one another, and there is interaction between them. In this study, pile–soil–pile interaction in a group of battered piles was numerically simulated using finite element analysis. Double and frictional pile groups under static lateral and axial loadings were analyzed separately. The effects of batter angle, slenderness ratio, spacing between piles, pile–soil stiffness ratio, and soil plasticity on interaction factors were computed and presented in curves. 相似文献
14.
Yongjiang Shen Yang Yu Fei Ma Feilong Mi Zhengliang Xiang 《Environmental Earth Sciences》2017,76(16):586
Double-row stabilizing piles provide larger stabilizing force and lateral stiffness than the single ones. However, the loading shared by the front and rear pile is not the same with each other because of the shadow effects. A double-row long-short stabilizing pile system is verified in this paper. Physical model tests are used to investigate the influence of short rear pile on the earth pressures evolution in the stabilized soil. Numerical models are established and calibrated with the applied displacement–force curve and monitored earth pressure in the physical model test. The influence of the short rear stabilizing pile on the soil–pile interaction is further investigated based on the numerical model. The soil–pile relative displacement, total stabilizing force and bearing proportion of front and rear stabilizing pile are used to evaluate the soil–pile interaction. It is concluded that the total stabilizing force and bearing proportion of front and rear stabilizing pile are not significantly influence by the short rear stabilizing pile when the double-row piles are arranged in a line. When the double-row piles are arranged in a zigzag form, the total resistance provided by the double-row stabilizing piles decreases as the short rear piles are being used. 相似文献
15.
This study presents an analysis of the displacement interaction among general configurations of energy piles bearing on stiff soil strata that are subjected to thermal loads. This work integrates recent analyses investigating the displacement interaction among predominantly floating energy piles subjected to thermal loads in deep uniform soil deposits. To address this challenge, design charts for energy piles resting on either infinitely or finitely rigid soil strata are presented, applied and validated for the analysis of the vertical displacement of predominantly end-bearing energy pile groups subjected to thermal loads using the interaction factor method. 相似文献
16.
在大桩径、小桩距的群桩条件下,不仅有来自桩侧、桩端和承台传递的多重应力叠加,还有群桩对桩间土的夹持作用影响,桩-土-承台之间作用更加复杂。用有限差分软件模拟固定桩距、桩径,变化竖向荷载下桩-土-承台的相互作用。从各层土的侧摩阻力、不同位置桩的桩顶荷载、荷载-沉降关系、桩间土体位移等方面的计算结果分析桩-土-承台之间的相互影响。结果表明,荷载超出117.8 MN（略大于Pu/2,Pu为群桩极限承载力）后,群桩对上部桩间土的夹持作用开始减小,桩侧上部侧摩阻力增大;桩侧下部侧摩阻力在多重应力叠加作用下呈减小趋势,不同位置的桩侧摩阻力影响范围有差异;用群桩沉降达到5%倍桩径时的荷载作为群桩的竖向极限承载力是可取的;当沉降与桩径的比值超出1%后,承台分担荷载的比例逐渐增大,群桩分担荷载的比例减小。 相似文献
17.
Yoon Seok Choi Jintae Lee Monica Prezzi Rodrigo Salgado 《Geotechnical and Geological Engineering》2017,35(4):1587-1604
Although the loads applied on piles are usually a combination of both vertical and lateral loads, very limited experimental research has been done on the response of pile groups subjected to combined loads. Due to pile–soil–pile interaction in pile groups, the response of a pile group may differ substantially from that of a single pile. This difference depends on soil state and pile spacing. This paper presents results of experiments designed to investigate pile interaction effects on the response of pile groups subjected to both axial and lateral loads. The experiments were load tests performed on model pile groups (2 × 2 pile groups) in calibration chamber sand samples. The model piles were driven into the sand samples prepared with different relative densities using a sand pluviator. The combined load tests were performed on the model pile groups subjected to different axial load levels, i.e., 0 (pure lateral loading), 25, 50, and 75% of the ultimate axial load capacity of the pile groups, defined as the load corresponding to a settlement of 10% of the model pile diameter. The combined load test results showed that the bending moment and lateral deflection at the head of the piles increased substantially for tests performed in the presence of axial loads, suggesting that the presence of axial loads on groups of piles driven in sand is detrimental to their lateral capacity. 相似文献
18.
A modulus‐multiplier approach, which applies a reduction factor to the modulus of single pile p–y curves to account for the group effect, is presented for analysing the response of each individual pile in a laterally loaded pile group with any geometric arrangement based on non‐linear pile–soil–pile interaction. The pile–soil–pile interaction is conducted using a 3D non‐linear finite element approach. The interaction effect between piles under various loading directions is investigated in this paper. Group effects can be neglected at a pile spacing of 9 times the pile diameter for piles along the direction of the lateral load and at a pile spacing of 6 times the pile diameter for piles normal to the direction of loading. The modulus multipliers for a pair of piles are developed as a function of pile spacing for departure angle of 0, 90, and 180sup>/sup> with respect to the loading direction. The procedure proposed for computing the response of any individual pile within a pile group is verified using two well‐documented full‐scale pile load tests. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
19.
悬浮桩水平振动的动力刚度 总被引：3，自引：1，他引：2
通过将悬浮桩截面下土体等效为土桩,利用桩的水平振动土阻抗结果,分析了桩、土桩构成的组合桩在频率域内的动力响应,给出了黏弹性土层中黏弹性悬浮桩水平振动动力刚度的半解析解,得到了动力刚度随各种物性参数的变化曲线。在此基础上,研究了物性参数对刚度的影响,对比了细长桩和短粗桩的响应差异。结果表明,悬浮桩水平振动的动态刚度受桩长、土的软硬程度、水平激振频率等的影响,这些结果可以为工程设计提供参考依据。 相似文献