《Journal of Geotechnical and Geoenvironmental Engineering》杂志刊登“粘土中快速加载试验分析技术比较”

作者：Michael J. Brown and John J. M. Powell

刊物：《Journal of Geotechnical and Geoenvironmental Engineering》，2013年1月，139卷第1期，152–161页

关键词：桩载荷试验；静力试验；桩土作用；粘土；冰碛土；细粒土；阻尼

摘要：快速加载试验（RLT）技术（如静动法）已经逐渐发展为被普遍接受的静力试验和动力试验的替代技术。若取得与快速加载试验相等的静力荷载-沉降特性，现有卸载点法（UPM）对于粗粒土适用，但对粘土和粉土的预测较差。为克服上述缺点，改进后的UPM已经是可用于反映土壤类型，并且已经产生新分析技术的方法。为测试改进后的UPM以及新分析技术的性能，本文分析了两个粘土地点的桩试验。第一个研究地点由高-极高塑性的第四纪伦敦粘土构成，第二个地点由低-中塑性且主要成分为基质的冰积土构成。利用一种新分析技术对高塑性粘土的静力等效荷载-沉降特性得到的结果给出了最好的预测，并且该技术包含一个随桩沉降值而变化的土壤-特定速率影响参数（基于粘土的塑性指数进行选择）。UPM对于低-中塑性冰积土进行的试验效果通常较好，RLT对这些土也有很好的效果。研究结果表明：在更多的土壤类型中进行试验对分析技术发展有重要作用。最后基于研究结果，给出了包括桩沉降取决于阻尼影响参数和速率影响参数改变的UPM和Schmuker的改进技术。

Comparison of Rapid Load Test Analysis Techniques in Clay Soils

Authors: Michael J. Brown and John J. M. Powell

Journal: Journal of Geotechnical and Geoenvironmental Engineering, Volume 139, Issue 1 (January 2013), 152–161

Key words: Pile load tests, Static tests, Soil-pile interaction, Clays, Glacial till, Fine-grained soils, Damping

Abstract: Rapid load pile testing (RLT) techniques such as Statnamic were developed as an alternative to more frequently adopted static and dynamic tests. The existing unloading point method (UPM) for deriving equivalent static load-settlement behavior from rapid load tests seems to be adequate in coarse-grained soils but may result in poor prediction in clays and silts. To address these shortcomings, the UPM has been improved to reflect soil type, and new analysis techniques have been developed. To test the performance of the improved UPM and new analysis techniques, pile tests from two clay sites were analyzed. The first case study site was underlain by very to extremely high-plasticity Quaternary London clay, and the second site was underlain by low- to intermediate-plasticity matrix dominant glacial till. The best predictions of static equivalent load-settlement behavior for very-high-plasticity clay were obtained from a new analysis technique that incorporated a soil-specific rate effect parameter (selected on the basis of the clays’ plasticity index) that varied with pile settlement. In general, the UPM performed better for tests undertaken in the low- to intermediate-plasticity glacial till, as there is greater experience of RLT in these soils. The results of the study suggest that the development of analysis techniques would benefit greatly from tests in a wider variety of soil types. On the basis of the findings of this study, improvements to the UPM and Schmuker techniques are presented, which include pile settlement–dependent variation of the damping and rate effect parameters.

原文链接：http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000733