路堤荷载下复合地基固结特性数值分析-市政工程专业论文.docxVIP

摘要复合地基作为一种重要的技术手段，近年来在高等级公路软基处理中得到了广泛应 摘要 复合地基作为一种重要的技术手段，近年来在高等级公路软基处理中得到了广泛应 用，学术界对各型复合地基的研究也越来越多，但是目前对各类复合地基的对比研究还 比较少。本文采用PLAXIS有限元软件利用单位元模型和平面应交模型对路堤荷载下的 多种复合地基的固结问题进行对比分析，总结各种地基固结变形的特点和规律。全文主 要内容有以下几个方面： l、分别从竖向和径向孔压梯度方面分析了水泥搅拌桩端承桩复合地基固结速度快 于匀质土地基的原因，分析表明复合地基深层孔压梯度增大是加快了复合地基固结的主 要因素。 2、对比分析端承桩复合地基和悬桩复合地基的固结特点。与端承桩桩复合地基不 同，悬桩复合地基固结速度慢于匀质土地基，其原因主要是下卧层的附加应力增大，致 使下卧层孔压消散变慢。 3、对比分析强排水桩复合地基和弱排水桩复合地基的孔压以及孔压梯度的分布规 律。计算表明强排水桩以径向排水为主，孔隙水主要由桩间土向桩体流动；而弱排水桩 以竖向排水为主，孔隙水主要由桩体向桩问土流动。 4、分别采用单位元模型和平面应变模型对比分析。计算表明平面应变模型能更好 的反映路中间沉降大、路边沉降小的地基整体变形情况，其桩体最终沉降量小于单位元 模型，固结速度快于单位元模型。 关键词：复合地基，路堤荷载，固结，沉降 AbstractComposite Abstract Composite ground is being used abroad in recent years in treating the soft-ground under express highway,research about each kind ofcomposite ground in academic circles黜more and more，But at present contrast research were aill very few． This paper analyses many problems about consolidation chamctc裙of composite ground under embankment，and concludes their deformation rules，based on unit cell model and plane deformation model，using finite element soRware of PLAXIS．All the work done is as follows： 1．Analyze the reason why composite ground which reinforced by cement-mixed piles when they龇fully penetrated consolidate more quick than uniform soil ground separately from vertical and radial direction pore pressure and its gradient,The analysis indicated that pore pressure gradient increased in composite ground deep level is the main reason why it consolidate more quick． 2．Contrast research the consolidation characters of composite ground which reinforced by piles when they are partially penetrated and fully penetrated．Composite ground with floating piles is different with composite ground with end bearing piles，it consolidate more slow than uniform soil ground．the reason is that the additional s_hess increased in composite ground deep level，caused its pore pressure dissirlates more slow． 3．Contrast research the distribution rule of pore pressure and its gradient in compo