A two dimensional elastic-plastic finite element model was developed to analyze the settlement behavior of a PHC pile-supported widening embankment under different layout of the piles .The mechanism of the reduction of settle-ment and differential settlement of the widening embankment by installing some piles under the existing embankment was revealed .The optimal location of the improved zone with PHC piles and the spacing of PHC piles were investigated ac-cording to the settlement control standard for the Shanghai -Nanjing highway widening project .The results show that the piles installed into soft soil bellow the existing embankment can significantly reduce the final settlement at the center of the widening embankment and the post-construction transverse gradient on the surface of the widening embankment . When the height of the widening embankment improved by PHC piles which have caps with the width of 1 .2 m is not higher than 5 m and the thickness of the soft soil to be improved is smaller than 20 m ,the first row of PHC piles near the centerline of the widening embankment should not less than 4 .7 m from the toe of the existing embankment ,and the opti-mal spacing of PHC piles is 3 m .%采用二维弹塑性有限元方法,对不同布桩方式下PHC桩桩承式拓宽路堤的变形特性进行了数值模拟分析,研究了老路边坡下布桩减小拓宽路堤沉降和差异沉降的机理.基于沪宁高速公路拓宽工程沉降控制标准,对PHC桩加固区的位置和桩间距进行了优化.研究表明:老路边坡下布桩可以显著地减小拓宽路堤路中心处的最终沉降和路表工后坡率.在路堤高度不超过5 m且软基厚度不超过20 m情况下,桩帽宽1.2m的PHC桩加固软基时,第一排PHC桩应布设在老路边坡下距老路坡脚不小于4.7 m处,桩间距可放宽至3.0m.
展开▼
