工程科学学报2018，Vol.40Issue(3)：285-292,8.DOI:10.13374/j.issn2095-9389.2018.03.004
黏土中静压沉桩离心模型
Centrifuge modeling of jacked pile in clay
摘要
Abstract
Notable contributions to our improved understanding of jacked pile behavior in sand have been achieved through instrumented model pile tests in laboratory test chambers, at elevated g-levels in the centrifuge, and in the field. In recent years, research focusing on pile behavior in clay has declined. Consequently, predictive methods for pile capacity have not advanced beyond those pro-vided in American Petroleum Institute (API 2000) recommendations, which were based on research conducted in the early 1980s. This paper re-focuses attention on the shaft capacity of jacked piles in clay. Three centrifuge scale pile tests were performed in kaolin clay in the drum centrifuge at the University of Western Australia. The tests were performed in pre-consolidated blocks of kaolin, and were subsequently spun in the centrifuge at three different g-levels of 50g, 125g and 250g respectively. The piles were equipped with total pressure sensors located at different depths and were installed by jacking into samples of reconstituted kaolin clay. The kaolin clay samples were prepared to measure the range of the cone penetration test end resistance ( qt ) , undrained strengths ( su-Tbar ) , and overconsolidation ratios ( OCRs) . These pile tests were used to investigate the lateral stress changes (σr ) developed along the pile shafts during pile installation and equalization. In addition, the change in the value of lateral stress (△σr ) and the changes in pile shaft resistance during the pile tension test were discussed. The characteristics of the jacked pile in the clay with different over-consolidation ratios ( OCRs) were revealed. Furthermore, the centrifuge data were subsequently used to examine the current design methods for the evaluation of the shaft capacity of displacement piles in clay. The centrifuge test results show that during the pile penetration, a strong dependence of lateral stress on the relative depth of the pile tip ( h/B) develops, and the total radial stress, as measured in a particular soil horizon, is observed to decrease as the relative depth of the pile tip ( h/B) increases ( where h is the height of the sensor above the pile tip, and B is the diameter of the pile) . Based on the cone penetration test during the investigation, it is observed that the lateral stress developed on a displacement pile is strongly depended on the cone penetration test end resistance ( qt ) and the relative depth of the pile tip ( h/B) . It is shown that the empirical method allowing for a dependence of shaft friction on qt , and h provides good estimates of the shaft capacities measured in centrifuge experiments. The research results have certain theoretical and engineering significance for pile construction and bearing capacity design in the soft soil region.关键词
静压桩/径向应力/黏土/桩侧承载力/离心模型Key words
jacked pile/radial stresses/clay/shaft capacity/centrifugal model分类
建筑与水利引用本文复制引用
李雨浓,Barry M Lehane,刘清秉..黏土中静压沉桩离心模型[J].工程科学学报,2018,40(3):285-292,8.基金项目
国家自然科学基金青年基金资助项目(51408527) （51408527）
河北省自然科学基金青年基金资助项目(E2015203195) （E2015203195）
