长短桩组合路堤桩三维复合拱土拱效应分析  

A three-dimensional hybrid soil arching analysis method of composite embankment with long and short piles

作　　者：李波[1,2] 黄茂松[1,3] 

机构地区：[1]同济大学地下建筑与工程系,上海200092 [2]长江科学院水利部岩土力学与工程重点实验室,武汉430010 [3]同济大学岩土及地下工程教育部重点实验室,上海200092

出　　处：《岩土力学》2013年第1期203-210,220,共9页Rock and Soil Mechanics

基　　金：国家高技术研究发展计划(No.2007AA11Z117)

摘　　要：基于等长桩路堤桩土拱效应的Hewlett分析方法,提出均布荷载作用下长短桩组合路堤桩的三维复合拱土拱效应分析方法。采用有限元法形象描绘土拱效应形成的应力集中形态随长桩与短桩的桩长比不同时的变化,基于此提出三维复合拱的基本理论框架。引入土拱效应系数来表征土拱的强度状态,建立桩帽顶部平面的应力平衡微分方程,结合边界条件及土拱效应系数之间的关系计算长桩和短桩的桩-土应力比;当加筋体存在时,分区域对加筋体进行变形假设,建立考虑加筋体拉力的桩帽顶部应力平衡微分方程。与离心模型试验和现场实测结果及有限元方法的模拟结果进行比较,验证了此方法的合理性,进一步开展参数分析对主要影响因素进行等级评价。分析表明,加筋体的存在明显增大桩-土应力比,尤其当桩帽覆盖率比较小时效果更为明显。Based on the Hewlett method for analyzing composite embankment with equal length piles,a three-dimensional hybrid soil arching analysis method is developed to explore the load sharing ratio of composite embankment with long and short piles under uniform pressure.The basic theoretical framework of three-dimensional hybrid arching analysis is established based on the vivid description of the stress concentration obtained from the finite element analysis.The soil arching effect coefficient is adopted to feature the incremental generation and the progressive failure of the arches,which changes with the increase of the length ratio.The equilibrium differential equation on the pile caps is established.The stress concentration ratios of the long piles and the short ones are calculated through solving system of equations including the equilibrium differential equation,boundary condition equation and relational expression of the two different soil arching effect coefficients.When the geosynthetics is taken into account,the reinforcement tension is calculated through the assumed deformed curves.And then a new equilibrium differential equation over the elevation of the pile caps is generated.Eventually,the results of centrifuge tests,in-situ tests and the finite element method are compared with those from the analytical method and are found to be in good agreement.Furthermore,parameter analysis is performed to evaluate the main influence factors on the soil arching.The analysis shows that the pile-soil stress ratio of the composite embankment with geosynthetics is significantly larger than that of the embankment without geosynthetics,especially when the cap coverage rate is relatively small.

关 键 词：长短桩组合路堤桩 三维复合拱 桩-土应力比 

分 类 号：TU473.1[建筑科学—结构工程]