【作者】 杨建华；

【导师】 夏元友；

【作者基本信息】 武汉理工大学 ， 结构工程， 2008， 博士

【摘要】 碎石填料的高路堤是山区高速公路建设较为普遍的一种路基,由于许多碎石填料质量较差,压实困难,因此如何提高碎石高路堤的压实质量,减少路基的工后沉降量就成为山区高速公路建设急需解决的重要问题。强夯法处理方法由于其特殊的优越性在高速公路的路基加固中得到应用,但强夯处理碎石路基的加固机理和设计、施工参数的还缺乏相应的标准和理论依据,因此通过强夯处理碎石土路基的现场试验和沉降观测,结合数值模拟合理论分析,研究确定强夯处理碎石路基的施工和设计参数,对工程具有重要的理论和实际意义。在全面分析国内外强夯处理地基的理论分析和工程实践现状的基础上,通过常吉高速公路红砂岩和灰岩填石路基的强夯加固现场试验,以及强夯前后碎石土路基沉降特性的比较分析,对碎石土路基强夯加固机理、红砂岩和灰岩碎石路基强夯处理减小沉降的有效性与作用机理以及强夯加固路基的沉降预测方法等进行了深入的分析研究;其次,基于夯锤与土体的非完全弹性碰撞特点,结合动力基础半空间理论,建立了夯锤振动的动力平衡方程,得到了强夯冲击应力和土体变形的关系式,研究了强夯冲击应力和土体变形的相互关系和影响因素;同时通过强夯加固路基的现场试验,确定了碎石土路基的强夯设计参数,分析了强夯的加固效果和变形规律,并对比分析了红砂岩和石灰岩碎石土路基强夯加固的效果;最后,采用Ansys/Ls-dyna软件包建立强夯三维模型,对强夯的动力响应进行了数值模拟,研究了强夯作用下土体的应力应变规律,得到了强夯后土体的应力场和位移场,并对理论分析、现场试验和数值分析结果进行对比分析,验证了本论文理论分析的正确性、试验方法的合理性以及试验结果的可靠性、Ansys/Ls-dyna软件包对强夯数值模拟的准确性,最后,通过对强夯前后红砂岩碎石土雨水入渗的现场试验和理论分析,结合路基沉降特性的比较分析,探讨了强夯处理对减少红砂岩碎石路基雨水入渗和减小路基沉降的有效性与作用机理。更多还原

【Abstract】 With the rapid development of expressway,more and more high embankment was constructed and how to improve compaction quality or decrease post-construction settlement of embankment should be solved quickly.Dynamic compaction has been adopted to improve embankment for its wide adaptation to the soils,remarkable effects,economical building material even no mateatical,low cost and short construction period etc.However,some problems in the reinforcement mechanism and design theory was exised due to the shortage of the design standard and theoretical basis of dynamic compaction,and the design of its construction parameters has been experiential and confused.In this case,it has to be determined by means of small scale tests and caused the result for the architects act blindly and randomly.In combination with the dynamic compaction construction for Changde-Jishou expressway,dynamic compaction methed to improve crushed-stone embankment is systematically studied.Firstly,based on comprehending the recent study of dynamic compaction technique and engineering practice,deepcutting study on tamping-strengthening principle,mechanism of tamping-energy transmission and mechanism of faster consolidation settlement combining dynamic compaction with roller compaction is carried out.Secondly,considering the characteristic of non-perfect elastic collision and the theory of dynamic foundation in half space, vibration equilibrant equation of hammer is established and the process of impact is analyzed.Solutions of impact stress and deformation are also abtained,furthermore, the influence factors and orderliness of impact stress and deformation are researched in theory.Thirdly,the paper determines the parameters of dynamic compaction and analyzes the improvement effect and deformation orderliness via a novelty in-situ experiment.The strengthening effect on Crushed Red-sandstone embankment is analyzed comparing with Crushed Limestone embankment.Finally,3D FEM model of dynamic compaction is established.The numerical simulation of whole dynamic process is carried out and the coutours of displacement & stress are obtained with explicit dynamic finite element program Ansys/Ls-dyna.The results show that the orderliness of stress & strain are quite consistant with the experiment results and theoretical analysis results.All above results illuminate the correctness of theoretical analysis,rationality of experiment method,reliability of experiment results and the accuracy for numerical simulation by Ansys/Ls-dyna.更多还原