共查询到20条相似文献，搜索用时 31 毫秒
1.
A. P. S. Selvadurai 《国际地质力学数值与分析法杂志》1983,7(2):209-223
This paper examines the interaction between a rigid circular foundation resting in smooth contact with an isotropic elastic halfspace and a concentrated surface load which acts at a finite distance from the foundation. Owing to the action of the external load the rigid foundation experiences an extra settlement and a tilt. The expressions for the extra settlement and the tilt are evaluated in exact closed form. It is also shown that these deformations due to the external load satisfy Betti's reciprocal theorem. The auxiliary solution required for the application of the reciprocal theorem is derived from the analysis of the problem of a rigid circular foundation resting in smooth contact with an elastic medium and subjected to an eccentric load. The, results developed for the interaction between the rigid circular foundation and the external concentrated load are utilized to generate, among others, solutions for the settlement and tilt induced at a rigid foundation due to its interaction with uniformly or non-uniformly distributed loads with circular and square plan shapes. 相似文献
2.
A. P. S. Selvadurai 《国际地质力学数值与分析法杂志》1980,4(2):121-129
This paper examines the problem of the eccentric loading of a rigid circular disc-shaped foundation embedded in bonded contact with an istropic elastic medium of infinite extent. The solution of this problem is achieved by using a Hankel integral transform technique which reduces the problem to two sets of dual integral equations. These systems of dual integral equations represent the equations which govern the axisymmetric and asymmetric states of deformation induced by the loaded foundation. Explicit results are derived both for the displacement and rotation of the circular foundation and for the contact stress at the interface. 相似文献
3.
Ahmed M. Fahmy John R. de Bruyn T. A. Newson 《Geotechnical and Geological Engineering》2013,31(5):1525-1542
Two-dimensional plane strain finite element analysis has been used to simulate the inclined pullout behavior of strip anchors embedded in cohesive soil. Previous studies by other researchers were mainly concerned with plate anchors subjected to loads perpendicular to their longest axis and applied through the centre of mass. This paper investigates the behavior of vertical anchors subjected to pullout forces applied at various inclinations with respect to the longest anchor axis, and applied at the anchor top and through the centre of mass. The effects on the pullout behavior of embedment depth, overburden pressure, soil–anchor interface strength, anchor thickness, rate of clay strength increase, anchor inclination, load inclination and soil disturbance due to anchor installation were all studied. Anchor capacity is shown to increase with load inclination angle for anchors loaded through the centre of mass; greater effects are found for higher embedments. The results also show that anchor capacity improves at a decreasing rate with higher rates of increase of soil shear strength with depth. In addition, the capacity of vertically loaded anchors is shown to approximately double when the soil–anchor interface condition changes from fully separated to fully bonded. Similarly, disturbed clay strengths adjacent to the anchor following installation cause a significant reduction in anchor capacity. The results showed a significant effect of the point of load application for anchors inclined and normally loaded. The effects of other parameters, such as anchor thickness, were found to be less significant. 相似文献
4.
A. P. S. Selvadurai 《国际地质力学数值与分析法杂志》1993,17(5):343-353
The present paper examines the axisymmetric problem related to the loading of a rigid circular anchor plate which is embedded in bonded contact with an isotropic elastic half-space. A Hankel transform development of the governing equations is used to reduce the associated mixed boundary value problem to a set of coupled Fredholm integral equations of the second kind. These equatons are solved in a numerical fashion to generate results of engineering interest. In particular, the results indicate the influence of the depth of embedment on the axial stiffness of the rigid anchor plate. 相似文献
5.
斜向荷载作用下抗拔螺旋桩基础的研究选用螺旋桩为研究对象,引入了随动坐标系,并将桩-土相互作用形成的地基反力以载荷的形式施加于桩体和叶片,解决了大变形材料使用小变形弹性材料叠加原理问题,分析了斜向荷载抗拔螺旋桩基础的破坏模式,建立了斜向荷载作用下抗拔螺旋单桩和群桩基础的极限荷载估算公式,通过与螺旋群桩原型试验的极限荷载判定值的对比,斜向极限荷载估算值约为判定值的93.3 %。表明所使用的研究方法,提出的破坏模式和极限荷载计算方法比较符合实际情况,对斜向荷载抗拔螺旋桩基础工程的设计与分析有一定的指导意义。 相似文献
6.
锚杆抗滑桩内力计算的初参数法研究 总被引：1，自引：0，他引：1
将锚索抗滑桩看作由锚索和抗滑桩共同组成的支挡结构系统,同时,将其中的抗滑桩视为搁置在弹性地基上的梁,并将锚索拉力作为集中力加在抗滑桩上;应用初参数法分别建立了滑面上下基床参数为同一常数和滑面上下基床参数为不同常数时的计算锚索抗滑桩弯矩、剪力、挠度和转角的初参数公式。以某滑坡治理工程中采用的锚索抗滑桩为例,对其内力进行了计算。 相似文献
7.
A general method is presented for the analysis of horizontally embedded anchors in an elastic soil. Provision is made in the analysis for the consideration of anchor shape, layer depth, anchor–soil interface condition, breakaway of the anchor from the underlying soil and interaction between groups of anchors. Application of the analytical technique is illustrated for strip and circular anchors, and these solutions are presented in the form of influence charts which may be used directly in hand calculations to predict the elastic load deflection behaviour, of anchor plates for a wide variety of material and geometric conditions. 相似文献
8.
WangYuanhan GongWenhui 《中国地质大学学报(英文版)》2004,15(4):401-408
The vibration analysis of a plate on an elastic foundation is an important problem in engineering. It is the interaction of a plate with the three-dimensional half space and the plate is usually loaded from both the upper and lower surfaces. The contact pressure from the soil can not be predefined. According to Lambs solution for a single oscillating force acting on a point on the surface of an elastic half space, and the relevant approximation formulae, a relation between the local pressure and the deflection of the plate has been proposed. Based on this analysis, the reaction of the soil can be represented as the deformation of the plate. Therefore, the plate can be separated from the soil and only needs to be divided by a number of elements in the analysis. The following procedure is the same as the standard finite element method. This is a semi-analytical and semi-numerical method. It has been applied to the dynamic analysis of circular or rectangular plates on the elastic half space, at low or high frequency vibration, and on rigid, soft or flexible foundations. The results show that this method is versatile and highly accurate. 相似文献
9.
A. P. S. Selvadurai 《国际地质力学数值与分析法杂志》1989,13(2):159-170
The problem of the axial loading of a rigid disk-shaped anchor plate embedded in an isotropic elastic medium of infinite extent is examined. At the boundary of the disk anchor plate the elastic medium contains a cracked region of finite extent. The presence of the cracked region decreases the elastic stiffness of the anchor plate. The mathematical formulation of the problem is developed, and a numerical scheme is presented which can be used to solve the resulting coupled integral equations. The numerical technique is used to evaluate the results, which illustrate the manner in which the elastic stiffness of the anchor plate is influenced by the extent of cracking. Similar results are developed for the flaw shearing mode stress intensity factor at the external boundary of the cracked region. 相似文献
10.
利用三维非线性弹性有限元方法,研究了刚性桩复合地基在不同垂直荷载作用下的水平承载力特性,分析了不同褥垫层厚度及其地基土的性质对复合地基水平受力特性的影响,得出了水平荷载作用下桩身弯矩和挠度的分布规律。研究表 明,垂直荷载的大小改变了复合地基水平荷载作用下的破坏模式,直接影响着其水平承载力;适当的垫层厚度可降低桩所分担的水平荷载,有利于桩身的安全。 相似文献
11.
A. P. S. Selvadurai 《国际地质力学数值与分析法杂志》1978,2(2):189-197
The equations governing the undrained linear elastic behaviour of a saturated soil are formally similar to the equations governing slow of an incompressible Newtonian viscous fluid. This principle of equivalence can then be effectively employed to obtain the load-deflection reiationship for a deep rigid anchor with the shape of a solid of revolution which is embedded in bonded contact with an unbounded incompressible elastic medium. It is found that the load-deflection relationship for the deep rigid anchor can be directly recovered from the expression for the drag induced on an impermeable object with the same size and shape as the anchor, which is appropriately placed in a slow viscous flow region of uniform velocity. 相似文献
12.
用解析方法研究了管桩在轴向力和水平向力（倾斜力）联合作用下的受力及变形性状。在高层建筑、桥梁工程、海洋工程、新型海堤护岸等工程中桩基自由长度上作用土压力、风荷载、波浪荷载等荷载型式,基桩经常在竖向、水平向荷载同时作用下工作。国内外学者通过大量试验和理论研究得出了计算竖向、水平向荷载下基桩内力和挠度的半经验公式以及张氏法公式。为了分析竖向、水平向荷载同时作用下自由荷载的作用,在现行m法假设的基础上,从弹性桩的挠曲微分方程出发,导出了任意自由荷载作用下桩任意截面的水平变位、倾角、弯矩、剪力和地基反力计算表达式。桩的挠曲微分方程是分段函数,包括地上部分和地下部分桩,相应的内力和变位求解也分为两段。最后通过一个算例分析了桩顶竖向荷载、桩顶水平力和自由荷载对桩身的受力性状各参数的影响。计算结果表明, 桩顶水平力对桩身最大弯矩和桩顶水平变位的影响最大,而桩周内外摩阻力及桩身自重对桩身受力性状影响较小。 相似文献
13.
Leonidas T. Stavridis 《Geotechnical and Geological Engineering》2009,27(3):407-417
A rigid foundation of arbitrary shape resting on a stratified half space (soil), with specific geometrical and elastic properties
for its horizontal layers, is examined under the action of a vertical load placed anywhere on the foundation area. On the
basis of a purely analytical treatment of the deformability of the soil surface, i.e. without using a finite element discretization
of the layered soil mass, a general method is developed in order to determine the contact soil pressures and the resulting
settlements through an easily implemented numerical procedure. The possible presence of “inactive” foundation parts not being
in contact with the soil surface is taken into account. Parametric studies are performed showing the influence of the variability
of the soil layers, as well as of the vertical load location, on the contact pressures developed. In this context, for the
cases of a rectangular and a circular foundation the area borders for the location of a vertical load are determined, either
for the development of compressive soil pressures all over the footing (core), or for allowing the existence of some inactive
part without contact with the soil (zero contact pressure), not exceeding the half of the total foundation surface (limit
core). 相似文献
14.
竖向圆形荷载作用下弹性半空间问题的位移和应力解是桩基分析的基础。利用Hankel积分变换,首先导出了弹性地基半空间位移与应力的积分形式的通解。通过适当地引入边界条件和界面位移和应力的连续条件,求得了内部作用竖向圆形荷载时弹性地基半空间位移与应力的积分形式解。在此基础上,给出了不同深度处荷载作用投影范围内竖向位移和竖向正应力的平均值。数值结果验证了解析解的正确性。 相似文献
15.
A. P. S. SELVADURAI 《国际地质力学数值与分析法杂志》1996,20(5):351-364
The present paper examines the elastostatic problem pertaining to the axisymmetric loading of a rigid circular foundation resting on the surface of a non-homogeneous elastic half-space. The non-homogeneity corresponds to a depth variation in the linear elastic shear modulus according to the exponential form G(z)=G1+G2e-ζz. The equations of elasticity governing this type of non-homogeneity are solved by employing a Hankel transform technique. The mixed boundary value problem associated with the indentation of the half-space by the rigid circular foundation is reduced to a Fredholm integral equation which is solved via a numerical technique. The numerical results presented in the paper illustrate the influence of the near-surface elastic non-homogeneity on the settlement of the foundation. 相似文献
16.
Mete Oner 《国际地质力学数值与分析法杂志》1990,14(9):613-629
Vertical and horizontal deformations of surface footings have been studied for an inhomogeneous elastic half-space in which the shear modulus increases with an arbitrary power of depth, n, and Poisson's ratio is constant. A general solution for displacements has been obtained first for point loads applied in vertical and horizontal directions. These are then used in obtaining closed-form solutions for displacements of uniformly loaded circular and rectangular footings. Finally, a numerical method is described that can be used to analyse a rigid footing of an arbitrary shape, and results for rigid rectangular footings are given. 相似文献
17.
《Geomechanics and Geoengineering》2013,8(4):267-275
Pseudo-static approach is adopted in this paper to determine the seismic uplift capacity of an inclined strip anchor using upper bound limit analysis. Two different failure mechanisms are considered to obtain the magnitudes of unit weight component of uplift factor fγE for different values of soil friction angle, interface friction of anchor plate, anchor inclination, embedment ratio and horizontal seismic acceleration coefficient. The failure mechanism 1 consists of a triangular and quadrilateral rigid blocks; whereas the failure mechanism 2 comprises a logarithmic spiral failure zone with varied focus, sandwiched between a triangular and quadrilateral rigid blocks. It is observed that the magnitude of uplift factor fγE decreases significantly with the increase in seismic acceleration but increases with the increase in embedment ratio and roughness of the anchor surface. However, a mixed trend in the values of fγE can be observed for different inclination of the anchor, which is clearly discussed in this paper. The results are compared with the existing values in the literature and the significance of the present methodology for designing the inclined strip anchor is discussed. 相似文献
18.
利用点荷载,作用于半无限空间的Mindlin位移解,考虑锚杆与土体界面的渐进破坏过程,推导出界面摩阻力的微分方程解析解。编制了相应的计算程序,把计算结果和现场试验值进行比较,结果较为吻合,二者的数据都表明,随着锚头拉力的增加,土-锚杆摩阻力峰值逐渐向锚杆末端转移,而锚杆前端则发生部分范围的滑移。然后,利用所求得的解析解,研究了土体弹性模量、锚杆孔径对锚杆摩阻力分布的影响,可见土体弹性模量越大,则界面上的摩阻力越容易达到峰值,从而产生破坏,而锚杆孔径越大,则界面上的摩阻力上升越慢,可延缓破坏过程。 相似文献
19.
The ultimate capacity of anchors is determined using the material point method (MPM). MPM is a so‐called meshless method capable of modelling large displacements, deformations and contact between different bodies. A short introduction to MPM is given and the derivation of the discrete governing equations. The analysis of a vertically loaded anchor and one loaded at 45° is presented. The load–displacement curves are compared to that obtained from experiments and the effect of soil stiffness and anchor roughness is investigated. The results of the vertically loaded anchor are also compared to an analytical solution. The displacement of the soil surface above the anchor was measured and compared to the numerical predictions. Convergence with mesh refinement is demonstrated and the effect of mesh size and dilatancy angle on the shear band width and orientation is indicated. The results show that MPM can model anchor pull out successfully. No special interface elements are needed to model the anchor–soil interface and the predicted ultimate capacities were within 10% of the measured values. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
20.
This paper presents a mechanical analogue which models the response of a rigid circular footing on an ideal elastoplastic half-space to transient loads. In the rational analysis of pile-driving dynamics, the response of soil at the base of a pile is often approximated by a footing on a semi-infinite half-space. Most existing base models employ the well-known Lysmer analogue to model the elastic response of the soil at the pile base, and account for the inelastic soil behaviour through the inclusion of a plastic slider with a slip load equal to the ultimate failure load of the footing. The improved model provides a force response which is significantly closer to the ideal response than existing models. The paper commences with a review of analytical solutions for the dynamic response of a rigid circular footing on an elastic half-space. Existing mechanical analogs for the system are reviewed, and an automatic matching process proposed which improves the accuracy of the analogs under transient loading. The inelastic response is then studied using the finite element method, and the mechanical analogs are modified to allow representation of the observed inelastic behaviour. Examples are presented illustrating close agreement between the proposed models and finite element analyses for a range of Poisson's ratio. The improved models have direct application for one-dimensional models of pile driving, particularly in the back-analysis of data from dynamic testing of piles. They are also applicable to studies of dynamic compaction. 相似文献