一级公路路基拓宽差异沉降影响因素及控制标准分析

发布时间：2018-01-12 23:16

  本文关键词：一级公路路基拓宽差异沉降影响因素及控制标准分析　出处：《合肥工业大学》2015年硕士论文　论文类型：学位论文

  更多相关文章： 一级公路 路基拓宽 差异沉降 影响因素 控制指标

【摘要】：在一级公路改造工程设计施工过程及道路运营阶段中,新老路基间的差异沉降问题不可避免,为分析研究一级公路拓宽路基差异沉降关键影响因素及其控制标准问题,本文依托实际工程,选取ABAQUS分析软件采用有限元法基于饱和土单向固结理论对一级公路拓宽路基差异沉降进行计算,分析探讨了路基拓宽宽度、路基高度、路基填料模量、路基模量关键因素对差异沉降的影响,并从设计、施工以及路面结构使用角度研究拓宽路基差异沉降控制指标,得出以下研究结论：(1)分析一级公路路基拓宽工程的主要病害形式,总结路基差异沉降形成原因主要包括拓宽路基压实度不足、高填方路基、新老路基结合部强度不足等,在设计和施工各环节应针对形成原因采取有效工程措施来避免或减少不均匀沉降。(2)拓宽路基顶面沉降变化曲线总体呈“勺”形变化,老路路基和拓宽路基的总体等效应力水平虽不大,但在新拓宽路基顶部中间位置出现应力集中现象,在实际拓宽路基施工中需在路基结合部加铺土工格栅等措施来防止应力过大导致结构层发生破坏。(3)采用正交试验设计法对路基拓宽宽度、路基高度、路基填料模量、路基模量四个拓宽路基差异沉降关键因素进行综合分析,以路基顶面竖向沉降和水平位移为考核指标,得出对竖向沉降影响程度最大的影响因素为路基拓宽宽度。(4)对路基不同拓宽方式在不同拓宽宽度情况下的路基顶面沉降进行分析可知,当路基拓宽宽度增加至8m后,拓宽路基最大沉降出现位置处出现了反坡效应,建议单侧拓宽宽度以8-12m为宜。(5)对不同路基填土高度时拓宽路基顶面差异沉降变化分析可知,随着路基填土高度不断增大,拓宽路基中差异沉降值逐渐增大；路基土的弹性模量对于新拓宽的路基部分影响程度较大,随着弹性模量增加,新拓宽路基顶面不均匀沉降量呈下降趋势,施工时路基土的各项特性需通过现场试验严格保证。(6)经探讨研究,建议在施工完成时以横坡斜率偏差i≤0.3%作为检验道路工程施工质量控制指标,以路面变坡率i ≤0.46%作为路面结构使用阶段差异沉降控制标准；本文建立的路基拓宽差异沉降限值S与新老路基拓宽比l、新路基填料弹性模量比k、路基高度h间的拟合方程式能较真实反映影响因素与路基拓宽差异沉降控制指标的内在规律,可为实际路基拓宽工程的设计与施工提供参考。
[Abstract]:In the design and construction process of the first class highway reconstruction project and the road operation stage, the differential settlement between the new and old subgrade is inevitable. In order to analyze and study the key factors and control standards of differential settlement of widening subgrade of first class highway, this paper relies on actual engineering. Based on the unidirectional consolidation theory of saturated soil, the differential settlement of the first grade highway widening roadbed is calculated by using the ABAQUS analysis software, and the width and height of the roadbed widening are analyzed and discussed. The influence of the key factors of subgrade filling modulus and subgrade modulus on differential settlement is discussed. The control index of widening subgrade differential settlement is studied from the angles of design, construction and pavement structure use. Draw the following conclusion: 1) analyze the main disease forms of the first class highway roadbed widening project, summarize the causes of the subgrade differential settlement, including the lack of compaction degree of the widening roadbed, high filling subgrade. The strength of the new and old roadbed joint is insufficient. In design and construction, effective engineering measures should be taken to avoid or reduce uneven settlement. Although the overall equivalent stress level of the old roadbed and the widening roadbed is not large, the stress concentration appears in the middle position of the new widening roadbed. In the actual widening of roadbed construction, some measures such as adding geogrid to the junction of roadbed are needed to prevent the damage of structural layer caused by excessive stress.) the orthogonal test design method is used to widen the width and height of roadbed. The four key factors of widening the differential settlement of subgrade are comprehensively analyzed, and the vertical settlement and horizontal displacement of the top surface of the roadbed are taken as the evaluation index. It is concluded that the most influential factor of vertical settlement is the width of roadbed widening. 4) the settlement of the top surface of subgrade with different widening ways is analyzed. When the width of roadbed widening is increased to 8 m, the reverse slope effect occurs at the position where the maximum settlement of the widening roadbed appears. It is suggested that the width of unilateral widening should be 8-12m.) the analysis of the differential settlement of the top surface of widening roadbed with different filling height of roadbed shows that the height of embankment is increasing with the increase of the height of embankment. The differential settlement value in widening roadbed increases gradually; The elastic modulus of subgrade soil has a great influence on the newly widened subgrade. With the increase of elastic modulus, the uneven settlement of the top surface of the new widening roadbed shows a downward trend. The characteristics of subgrade soil should be strictly guaranteed by field test during construction. After discussion and study, it is suggested that the slope deviation I 鈮，

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