The design and performance of piles socketed into weak rock
The design and performance of piles socketed into weak rock
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DOI：
10.4225/03/589aa1a34c4da
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发表时间：
1980-03
影响因子：
2.1
通讯作者：
Adrian F. Williams
中科院分区：
文献类型：
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作者：
Adrian F. Williams
本论文所描述的研究旨在了解软岩（即墨尔本泥岩）中嵌岩桩的性状，并为此类桩的设计开发一种实用而合理的方法。墨尔本泥岩的强度和压缩特性已被认为是通过一个程序的实验室和现场测试，重点B排水性能。通过试验，得到了排水强度和压缩性参数与含水量的相关关系。考虑的其他属性包括矿物学、粒度分布、渗透性和固结系数。实验室工作包括一项专门研究，以模拟侧阻力的作用。这是通过开发恒定法向刚度直剪机来实现的，该直剪机模拟了岩体的刚度，从而允许法向应力随着剪切和膨胀的发生而发展。这些结果已被认为是与岩石节理的抗剪强度的概念，并有助于发展嵌岩桩的侧阻力的理解。本文通过对49个现场嵌岩桩试验资料的分析，探讨了嵌岩桩的工作性能。这些测试中有一半以上是在原型桩上进行的，其余的是在较小的桩上进行的。测试包括设计成仅通过侧阻力或基底阻力承载荷载的桩、设计成侧阻力和基底阻力共同作用的桩以及设计成调查施工实践的桩。在不同地点进行桩试验，以评估岩石强度、模量和接缝频率的变化。一些桩上装有应变仪，以便计算荷载分布。在可行的情况下，测试桩被挖掘，以揭示故障机制。实验室和现场试验的结果已总结成一组设计曲线。这些曲线和其中包含的概念已被用于开发一种设计方法，该方法反映了嵌岩桩的观察行为。特别注意的是侧阻力和基础阻力之间的荷载分配和非线性荷载-沉降特性，包括侧阻力分量的峰值和基础阻力分量的工作强化。设计方法基于初始的线性弹性分析，然后通过应力松弛来考虑非线性效应。因此，它是以理论弹性解、实验室试验和现场试验相结合为基础的，并包括施工实践的影响。该设计方法可应用于只考虑桩侧阻力或桩底阻力的设计，也可应用于考虑桩侧阻力和桩底阻力共同作用的设计。设计曲线主要是针对墨尔本泥岩开发的，建议需要进一步的工作来开发其他岩石的适当曲线。主要设计概念被认为适用于广泛的条件。
The research described in this thesis has been undertaken to obtain an understanding of the behaviour of rock socketed piles in weak rock, viz. Melbourne Mudstone, and to develop a practical and rational method of design for such piles. The strength and compressibility properties of Melbourne Mudstone have been considered through a programme of laboratory and field tes ts, with the emphasis b on the drained properties. It has been possible to d correlations of the drained strength and compressibility parameters with moisture content. Other properties considered include mineralogy, particle size distribution, permeability and coefficient of consolidation. The laboratory work included a special study to model the action of side resistance. This was achieved with the development of a constant normal stiffness direct shear machine which modelled the stiffness of a rock mass and thus allowed for normal s tresses to develop as shearing and dilation occurred. These results have been considered with concepts relating to the shear strength of rock joints and have assisted in developing an understand of side resistance in rock socketed piles. The performance of rock socketed piles has been considered through the analyses of 49 field e tests, of which 43 were made during the course of this project. More than half of these tests were made on prototype sized piles, with the remainder being made on smaller piles. The tests included piles designed to carry load by side or base resistance only, piles designed for side and base resistance to act together, and piles designed to investigate construction practices. The pile tests were made at different sites to allow variation in rock strength, modulus and joint frequency to be assessed. Some piles were instrumented with strain gauges to enable load distributions to be calculated. Whenever practicable, the tested piles were excavated to reveal the failure mechanisms. The results of the laboratory and field tests have been summarized in a set of design curves. These curves and the concepts contained in them have been used to develop a design method which reflects the observed behaviour of rock socketed piles. Particular attention has been given to the distribution of load between side and base resistance and to the non-linear load-settlement characteristics, including the peaking of the side resistance component and the work strengthening of the base resistance component. The design method has been based on an initial linear elastic analysis, followed by the relaxation of stresses to allow for non-linear effects. It has thus been based on a combination of theoretical elastic solutions, laboratory tests and field tests, and includes the effects of construction practice. The design method may be applied to designs for side or base resistance only piles, or to piles with side and base resistance acting together. The design curves have been developed primarily for Melbourne Mudstone, and it is suggested that further work is needed to develop the appropriate curves for other rocks. The main design concepts are considered to be applicable to a wide range of conditions.