【作者】 朱志铎；

【导师】 刘松玉；

【作者基本信息】 东南大学 ， 岩土工程， 2006， 博士

【摘要】 在粉土地区的高速公路建设中,从粉土的基本特性出发,寻求合适的稳定材料与稳定方法,分析交通荷载作用下稳定粉土路基变形特性,对高速公路设计与施工具有重要的理论意义和实际价值。本文结合江苏地区高速公路建设,对区域性粉土进行了大量室内试验工作,系统研究了粉土的工程特性。从提高粉土本身的强度着手,同时考虑粉土的水稳定性、抗收缩性等性能,深入研究了粉土的固化机理,提出了粉土固化材料的可能组分;通过室内初步选择试验、正交试验、优化试验和多种稳定材料的对比试验,结合固化剂与粉土相互作用的微观分析,得到高性能粉土固化剂（SEU-2型）的最佳配比;根据多种粉土稳定材料填筑路堤的实体试验,掺入4%SEU-2型固化剂的稳定粉土路基具有优良的物理力学性能和路用性能;针对粉土路基边坡的特性,通过室内外试验工作,研制成功既能有效地防治边坡冲刷破坏,又能有助于植物生长的液体固化剂（SEU-1型）。论文分析了交通荷载的特性,根据屈服面和加载面的概念和循环荷载下土体的变形特征改进了土体经典的弹塑性模型,以反映循环荷载作用下土体变形逐步累计的变化规律。运用FLAC3D中的FISH语言编制了相应的计算程序,分析了交通荷载作用下稳定粉土路基的三维动力响应,研究了土体参数对路基变形的影响。论文最后还分析了盐通高速公路采用不同路基设计方案时的变形和应力,确定了最优设计方案。论文主要研究成果包括:1.系统研究了区域性粉土的基本特性,针对粉土路基稳定出现的问题,从增强粉土稳定的胶凝效应和填充效应出发,深入研究了粉土的固化机理。通过大量的室内外试验,成功研制了适合于区域粉土稳定的新型固化剂（SEU-2型）,该固化剂不仅具有良好的物理力学性能和路用性能,而且具有较高的性价比。2.成功研制了适合于粉土路基边坡防护的液体固化剂（SEU-1型）,该固化剂不仅能有效地防护粉土路基边坡冲刷破坏,而且能有助于植物的生长。3.根据交通荷载作用下道路结构的基本特性,提出了能够反映土体在重复荷载作用下变形特性的弹塑性模型,并运用FLAC^3D软件中的FISH语言编制了相应的计算程序,分析了土体的阻尼参数ξ_min、f_min、弹性模量、粘聚力和内摩擦角等参数对土体位移的影响。在单次半正弦荷载作用下,残余位移和土体的最大位移及其比值都随土体的阻尼参数ξ_min、f_min、弹性模量、粘聚力和内摩擦角的增加而减小,在这些参数中,以粘聚力和内摩擦角对位移的影响最显著。在重复荷载作用下,土体在最初几次加卸载循环中的残余变形较大,随着循环次数的增加,加载压缩和卸载回弹变形逐渐接近,土体逐步表现出弹性变形的特点。4.对盐通高速公路稳定粉土路基的不同设计方案进行了动、静荷载下路基的变形和应力分析。在静力荷载下,路面位移和天然土层顶面处的应力在方案2时最小,其次为方案7,方案1、3、5计算结果相近;在压实土层顶面和天然土层顶面,不同方案的位移分布特征及大小顺序与路面相同,但数值较小;在荷载作用点应力最大,但随着深度应力很快衰减;在动力荷载下,由于阻尼的存在,路基中不同深度处的位移随时间迅速衰减,并具有相似的变化过程,不同方案的路基在2.5s后基本都达到应力稳定。综合分析,方案3（二灰土底基层+20cm 4%固化剂+40cm 6%石灰+压实土）为最优设计方案。更多还原

【Abstract】 For highway construction in the area of silt soil, a stabilizing method and appropriate stabilizing materials, which are dependent on the characteristics of silt, have to be investigated in order to satisfy the requirements of engineering. The deformation features of stabilized silt subgrade under traffic loading has also to be analyzed. This has important theoretical and practical meanings for highway engineering.Based on highway constructions of Jiangsu province, engineering characteristics of regional silt are investigated systematically through laboratory tests in this paper. From the points of silt strength improving, water stability, and anti-shrinkage property, the stabilizing mechanism is studied and the possible components of stabilizing material are proposed. The optimum ratio for individual components of high performance stabilizing agent （SEU-2） are obtained from laboratory tests, including preliminary selection tests, orthogonal tests, optimization test, comparison tests of multiple stabilizing materials, and microscopic tests of interaction between stabilizing agent and silt. According to full-scale field tests of silt subgrades stabilized with different agents, it is considered that the silt subgrade stabilized with 4 percent of SEU-2 has satisfying physical and mechanical properties and pavement performance. Considering the features of silt slope, the liquid stabilizing agent （SEU-1） has been successfully developed through laboratory and field tests. SEU-1 can prevent erosion of slope, and be helpful for plants growing. After the analyses of features of traffic loading, a new modified elasto-plastic model is proposed to describe the change pattern of accumulative deformation of soil under cyclic loading according to the concepts of yielding surface and loading surface. The corresponding program, which is compiled by FISH language in FLAC^3D, is used to calculate the 3D dynamic responses of stabilized silt subgrade under traffic loading and to discuss the effects of soil parameters on the deformation of subgrade. Finally, the deformation and stress in subgrade corresponding to different design schemes in Yan-Tong Highway are studied, and the optimal design scheme is proposed. The research results for this paper are as follows.（1） The fundamental characteristics of regional silt are investigated. From the points of gelling and filling effect of stabilized silt, the stabilization mechanism is studied. Through laboratory and field tests, a new stabilizing agent of silt （SEU-2） is developed successfully, which presents good physical and mechanical properties, pavement performance, and high performance-price ratio.（2） A new liquid stabilizing agent （SEU-1）, which is suitable for silt slope protection, has been developed successfully. This agent can prevent erosion of slope, and is helpful for plants growing.（3） According to the fundamental features of traffic loading, a new modified elasto-plastic model is proposed to describe the deforming characteristics of soils under cyclic loading. A更多还原