单桩静载荷试验极限承载力的预测   总被引：5，自引：0，他引：5  

余敏 《山西地震》2004,(3):5-6,24

桩基承载力对桩基抗震性能有很大影响。介绍了一种单桩静载荷试验极限承载力的预测法——多项式回归法。在静载荷试验中，由于种种原因终止荷载未达到极限荷载时，可用上述方法进行推测。同时通过实例对比说明，这种方法对于静载荷试验具有一定的经济效益。  相似文献   

桩基系统在地基液化和土体流动过程中的三维响应          下载免费PDF全文

SATO T  MATSUMARU T  MOON Y  ZHANG F  UZUOKA R 《地震工程学报》2005,27(1):22-29

松散的饱和砂土在液化之前可作为固体看待,但当过量的孔隙水压达到初始侧应力时它成为液体,之后又恢复其强度。这个过程不能各自单独处理,而应视为一个从固态到液态,或从液态到固态的连续变化过程。因此,整个伴随着地基液化———土体流动现象全过程应作为一个在固态和液态之间相变的系列过程。本文导出了一个简单的基本方程式,可以表达松散饱和砂土在液化和地基侧向滑移现象期间的固-液相转换。该基本方程式可用作桩基系统的动力分析,其适用性通过与弹塑性基本方程的比较得到验证。  相似文献   

无限层弹性地基中常轴力桩基的地震反应分析     

刘宗贤  李玉亭 《华南地震》1995,15(4):54-60

根据Ｗｉｎｋｌｅｒ地基模型，对桩基础通过特性分析建立了合理的力学模型。在动力分析的基础上，给出了桩基础横向自振特性及在常轴力与横向地震载荷作用下的强迫反应解析解。文中的解析公式为桩基础动力分析提供了一种新的解析方法。  相似文献   

弹性波反射法在桩基检测中的理论与应用   总被引：1，自引：0，他引：1  

林建生 《华南地震》1994,14(1):48-55

根据波动理论探讨了弹性波在砼桩中的传播衰减规律及反射特征，提出了判断桩基质量的有关理论依据，并结合工程实例应用弹性波反射法讨论了时域、频域分析法的基本原理及存在问题．  相似文献   

Viscous effects on penetrating shafts in clays     

Sandeep P. Mahajan  Muniram Budhu 《Acta Geotechnica》2006,1(3):157-165

The penetration of rigid objects such as piles and penetrometers into soils creates a zone of soil disturbance around them. The extent of this disturbed zone influences the resistance of the moving rigid body. This paper presents a theoretical framework to analyze the resistance in the disturbed zone created by a shaft penetrating a clay soil. The soil is modeled as a viscous material after it reaches failure [critical state (CS)]. The results of this analysis show that the viscous drag stress component on the shaft surface is influenced by the size of disturbed zone that has reached CS around the shaft, the shear viscosity of the soil and the velocity profile (or strain rate) in the CS zone around the shaft. The size of CS zone, the velocity profile and the viscosity of soil are interdependent. Large variation in viscous drag occurs when the size of the CS soil zone is less than four times the shaft’s radius. Limiting drag occurs when the size of the CS soil zone exceeds six times the shaft’s radius. The theoretical velocity distribution of the movement of soil in the CS zone shows that the soil is dragged along with shaft in the near field (close to the shaft surface) and moves upwards in the far field.  相似文献   

Dynamic response of a pile embedded in a porous medium subjected to plane SH waves     

Jian-Fei Lu  Dong-Sheng Jeng  Wei-Dong Nie 《Computers and Geotechnics》2006,33(8):404-418

In this paper, the frequency domain dynamic response of a pile embedded in a porous medium subjected to SH seismic waves is investigated. The surrounding porous medium of the pile is described by Biot’s poro-elastic theory, while the pile embedded in the porous medium is treated as a beam and described by a beam vibration theory. Using the Hankel transformation method, the fundamental solution for a half-space porous medium subjected to a horizontal circular patch load is established. According to the fictitious pile methodology, the second kind of Fredholm integral equation for the pile is established in terms of the obtained fundamental solution and free wave field. The solution of the integral equation yields the dynamic response of the pile to plane SH waves. Numerical results indicate that the parameters of the porous medium, the pile and incident waves have considerable influences on the dynamic response of the pile and the porous medium.  相似文献   

钻孔灌注断桩事故产生原因及处理措施     

尹康华 《云南地质》2006,25(2):218-221

简要介绍在钻孔灌注桩施工中发生的断桩事故的原因和处理措施。  相似文献   

Modeling of pile installation using contact mechanics and quadratic elements   总被引：1，自引：0，他引：1  

Kathrin A. Fischer  Daichao Sheng  Andrew J. Abbo 《Computers and Geotechnics》2007,34(6):449-461

In geotechnical engineering, numerical analysis of pile capacity is often performed in such a way that piles are modeled using only the geometry of their final position in the ground and simply loaded to failure. In these analyses, the stress changes caused by the pile installation are neglected, irrespective of the installation method. For displacement piles, which are either pushed or hammered into the ground, such an approach is a very crude simplification. To model the entire installation process of displacement piles a number of additional nonlinear effects need to be considered. As the soil adjacent to the pile is displaced significantly, small deformation theory is no longer applicable and a large deformation finite element formulation is required. In addition, the continuously changing interface between the pile and the soil has to be considered. Recently, large deformation frictional contact has been used to model the pile installation and cone penetration processes. However, one significant limitation of the analysis was the use of linear elements, which have proven to be less accurate than higher order elements for nonlinear materials such as soils.

This paper presents a large deformation frictional contact formulation which can be coupled consistently with quadratic solid elements. The formulation uses the so-called mortar-type discretisation of the contact surfaces. The performance of this contact discretisation technique is demonstrated by accurately predicting the stress transfer between the pile and the soil surfaces.  相似文献   

Wave equation analyses of tapered FRP–concrete piles in dense sand     

Mohammed Sakr  M. Hesham El Naggar  Moncef Nehdi 《Soil Dynamics and Earthquake Engineering》2007,27(2):166-182

Fiber-reinforced polymers (FRP)–concrete composites provide an attractive alternative to conventional pile materials such as steel, concrete and wood by improving the durability of deep foundations. In the current study, FRP tubes with different taper angles are filled with self-consolidating concrete (SCC) and driven into dense sand that is enclosed in a large pressurized soil chamber. Driving tests are conducted on FRP–SCC composite piles to determine how the pile material and geometric configuration affect its driving performance. Dynamic data is employed to determine the soil parameters in the TNO model (i.e., soil quake and damping constant) using the DLTWAVE signal-matching program. The driveability of FRP–SCC and traditional pile materials is compared using the wave equation analysis program PDPWAVE. The experimental data and the wave equation analyses indicate that the taper shape has a favourable effect on the driveability and static resistance of piles. It is also found that the driveability of FRP–SCC composite piles is similar to that of conventional prestressed concrete and steel piles. However, empty FRP tubes required a much higher driving energy. Their low flexural resistance along with risk of buckling can hinder their driveability in different soil conditions.  相似文献   

Numerical analysis of nonlinear soil–pile group interaction under lateral loads     

Hossein Tahghighi  Kazuo Konagai   《Soil Dynamics and Earthquake Engineering》2007,27(5):463-474

A nonlinear p–y element was provided which can simply model the behavior of a pile group foundation subjected to lateral loading. Its elasto-plastic side soil is expressed as a Winkler-type distributed model. Despite the simplification involved in modeling such a complex phenomenon the proposed nonlinear soil model can reproduce the system behavior as computed by more rigorous 3D finite element methods. The numerical results are also compared with those from available physical model data to confirm that our simulations can predict the behavior of pile groups with good accuracy.  相似文献