【作者】 姚占勇；

【导师】 练继建；

【作者基本信息】 天津大学 ， 水利水电工程， 2006， 博士

【摘要】 在黄河冲淤积平原,由于砂石料的严重缺乏,土是最基本的建筑材料。黄河冲淤积平原土是我国特有的土质,研究该土质的工程特性至关重要。试验分析了黄河冲淤积平原土的特点。研究发现,该土在结构上呈层状分布;物质组成以原生矿物砂砾为主,粘土矿物极少;颗粒分布上,粒度均匀,粉粒含量高达80%以上;由于黄河水的长距离搬运作用,颗粒磨圆度高、表面强度低;孔隙率高,毛细作用剧烈。区域内地下水位较高,土体具有较大压缩性。由于以上特点,黄河冲淤积土表现出难以压实、无机结合料稳定困难,地基沉降量大等工程特点。试验分析了黄河冲淤积土的压实性能。研究认为,该类土压实后高的孔隙率,是其强的毛细作用和高的冻敏性,以及低压实度时路基支撑强度不足、沉降较大的主要原因;土中小于0.005mm的颗粒含量反应了黄河冲淤积土的最佳碾压颗粒级配范围。通过振动台试验,研究了土的振动压实规律;通过试验路,提出了合理的压实工艺。试验研究了无机结合料稳定黄河冲淤积土的压实特性,强度规律,强度影响因素及其作用机理,配合比设计方法、养护方法、压实工艺等。研究认为,粘粒含量低是无机结和料稳定该类土性能差的主要原因。依据二灰土强度增长的阶段性,提出了合理的设计龄期。给出了二灰稳定黄河冲积土的设计控制参数与最佳配合比范围。提出了二灰土配合比设计的关键控制参数—土中<0.005mm颗粒含量范围,以及反映二灰土颗粒级配优劣与活性的重要参数—粗细颗粒比Cf。采用有限差分法,建立了黄河冲淤积平原粉性土公路地基沉降的流～固耦合模型,分析了地基沉降的规律,提出了不同填高的路基在施工结束后的放置期、工后沉降速率和最终固结时间。采用有限元法,分析了该区域高速公路路面结构的力学响应。提出了石灰土处理路床区以提高路面结构抗疲劳性能的工程技术措施。指出路面结构支撑条件、界面条件和层间刚度差是影响路面结构受力与使用寿命的三要素。提出了半刚性基层沥青路面结构的最大拉应力位置、临界荷载区域、严重超载时路基的影响深度与塑性变形位置。通过现场检测,验证计算结果的可靠性。更多还原

【Abstract】 It is seriously important to study the engineering characteristic of Yellow River alluvial-plain soil, as it is the most basic building material because of the lack of sandstone there, and a specific soil in our country.Through the experiment, the characteristics of the Yellow River alluvial-plain soil were analyzed. The soil presents in layered form on the structure, and is mainly made up of original mineral grit and rarely clay mineral. In the distribution of grain, it is epigranular, and the content of silt is more than 80%. It has high psephicity, low surface strengths, high porosity and intensive capillarity because of the long transport function of the water. It also has higher groundwater level in district and bigger compressibility. So the Yellow River alluvial soil expresses some engineering characteristics, such as, difficultly to be compacted and stabilized with inorganic binder, and large foundation depression.In the test, the compaction performance of the Yellow River alluvial soil was analyzed. The high porosity after compaction is the main reason of its strong capillarity and high frost susceptibility, as well as the larger foundation depression. The content of the grain, which is smaller than 0.005mm, reflects optimum grading limit of rolling grains. Through the jolter experiment, the vibrating compaction regulation of the soil was studied. The reasonable compaction craft was put forward on trial road.In the experimental investigation, the strength regulation, the strength influencing factors and its action mechanism, design method of ratio of conjugation, maintenance process and compaction craft of the Yellow River alluvial soil stabilized with the inorganic binder were studied. The low content of clay is the main reason that the performance of the soil stabilized with inorganic binder is poor. The reasonable design age was put forward based on the intensity phase of lime-flyash soil. The controlling parameter of Yellow River alluvial soil stabilized with lime-flyash soil and optimum ratio of conjugation limit were given. The key control parameter, the content of grains which is smaller than 0.005 mm, and the important parameter reflecting quality and activity of grain gradation--the coarse-to-fine grain ratio Cf, were taken out.The fluid-solid coupling model of foundation depression was set up through the finite difference calculus. The regulation of the foundation depression was analyzed. The resting period, sedimentation rate and consolidation time of different filled-up subgrades were extracted.The mechanical response of freeway pavement structure in this area was analyzed. The engineering technique measure, which is treating road bed to increase fatigue resistance, was put forward. And pointing out three factors which influence the stress and service life, they are poling condition of pavement structure, the interface and the rigidity difference between layers. The position of maximum tension stress of semi-rigid asphalt pavement structure, critical load zone, influencing depth and the position of plastic yield in the roadbad were presented. The reliability of compute results was verified by the field test.更多还原