【作者】 张建华；

【导师】 黄雪峰；

【作者基本信息】 兰州理工大学 ， 岩土工程， 2010， 硕士

【摘要】 近年来,随着西部大开发战略的实施,各类建筑物的大量新建,尤其是高层、超高层建筑、大跨桥梁等的需要,嵌岩桩以其单桩承载力高、变形小,施工简单,造价经济,在工程中得到了广泛的应用,成为大型建筑物重要的基础形式。虽然嵌岩桩应用较早,但其受力机理和工作特性仍存在许多问题有待深入研究。如：合理嵌岩深度的问题,嵌岩段摩阻力分布模式,嵌岩桩承载力计算问题,水平载荷作用下嵌岩桩的承载性状等。另外,关于桩端(岩)土层性质影响着桩端附近一定范围内的桩侧阻力发挥大小的现象已经引起了越来越多学者的关注,但是迄今为止,关于这方面的研究和试验资料比较少。本文通过现场竖向静载荷试验,分析了嵌岩桩的荷载传递机理、桩侧阻力和桩端阻力分布规律、及其二者之间的分担比等,同时还发现,在本次试验中桩端阻力对侧阻力也存在明显的强化效应现象。结合大型有限元软件ANSYS,对试验进行数值模拟,得到ANSYS计算结果与试验结果相近,模拟效果较精确,在此基础上,还探讨了竖向荷载作用下单桩在相同桩侧土,不同桩端岩(持力层)条件下的荷载传递机理及端阻对侧阻力强化效应现象。最后,在竖向静载荷试验结束后,还进行了水平静载荷试验,得到了水平荷载作用下嵌岩桩的水平力-时间-水平位移、水平力-位移梯度曲线及桩身应力分布和桩身弯矩分布,分析了嵌岩桩水平受荷性质及其机理。结果表明,嵌岩桩桩侧摩阻力在承担桩顶荷载的过程中起了很重要的作用,而在摩阻力中,上部土层发挥的作用不可忽视；端阻对侧阻的强化效应不仅发生在桩端附近,在桩身上部土层中也存在,强化效应的发生与桩端岩强度和端阻力发挥的大小有关系；水平荷载作用下桩身弯矩主要集中在0-6m范围内,6m以下弯矩较小,水平受荷桩钢筋笼不需全长配置,仅在桩身弯矩集中部位布设便可抵抗水平力所产生的弯矩。具体包括：1.单桩的荷载-沉降关系；2.单桩桩身轴力传递特征；3.单桩桩侧阻力分布规律,侧阻与端阻分担比及侧阻强化效应分析；4.通过单桩水平载荷试验,分析了水平荷载作用下嵌岩桩的承载性状及其影响因素,为合理进行水平受荷嵌岩桩的设计提供了依据。5.以有限元软件ANSYS为工具,建立不同桩端岩层强度条件下的单桩模型,分析荷载传递机理及强化效应现象。更多还原

【Abstract】 In recent years, with the implementation of the western development strategy, a large number of new types of buildings are springing up, especially high-rise, super high-rise buildings and long span bridges.so it posed the higher requirments for foundation.Because of high bearing capacity,small deformation,simple construction, cost economic,rock-socketed piles as an important basic form of large buildings have been widely used in the project. Although the application of rock-socketed pile more early, its stress mechanism and work characteristics exist many issues to further investigation. Such as the problem about a reasonable depth of embedded in rock, the distribution patterns of rock-socketed frictional resistance,bearing calculation of rock-socketed pile, the bearing characteristics of rock-socketed piles under the effect of loading and so on. In addition, the phenomenon about soil properties of the pile (rock) tips influencing the play of pile side resistance on a certain range has aroused more and more attention from scholars, but so far, the research and test information in this area are even less.Through testing on-site vertical static loading, this article analysis the load transfer mechanism of rock-socketed pile, pile side resistance and tip resistance distribution, and the ratio between the two sharing, and found that pile side lateral shear resistance strengthening effect is also obvious phenomenon in this test Using finite element soft ANSYS, the numerical simulation are more accurate and results are more similar with testing results, on this basis, this article also discussed load transfer mechanism of the single pile under vertical loading of soil in the same pile, different pile end rock (support layer) and the phenomenon of reinforced effect about the tip resistance to side resistance. Finally, at the end of the vertical static load testing, doing level static load testing obtain the curves of horizontal force-time-horizontal displacement, force displacement gradient and stress and moment distribution of pile shafe,and analysis the mechanism and characteristics of level loading of rock-socketed piles. The results showed that rock-socketed pile side friction in the commitment to the process of pile top load played an important role, and in the friction, the upper part of the role of soil can not be ignored; side effect of blocking the contralateral enhanced resistance not only occurs In the pile near the pile top soil there, strengthening effect of the occurrence of pile tip resistance of rock strength and size to play a relationship; level of bending moment under the load concentrated in the 0～6m range 6m moment the following small piles under lateral reinforcement cage without full configuration, only the bending moment concentration is laid horizontal force can resist the moment generated.Includes:1. the load-settlement of single-pile;2. column load transfer characteristics of single-pile shaft;3. Distribution single pile side resistance, the ratio of side friction and end resistance distribution;4. Finite element soft ANSYS as a tool to establish the model of different rock pile under strength condition, analyze the phenomenon of the load transfer mechanism and the strengthening effect5. Through level load testing of the pile, analysis bearing behavior of rock-socketed piles and the influencing factors at horizontal load, provide the basis of conducting a reasonable level of loaded rock-socketed pile design.更多还原