低填浅挖路段砂砾路基工作区深度及施工质量控制研究

Study on Depth and Construction Quality Control of Gravel Subgrade Working Area in Low Filling and Shallow Excavation Section

对低填浅挖路段砂砾路基填料的土工参数和强度性能予以探讨,针对其松散材料的特点,基于ABAQUS有限元软件对荷载附加应力和路基自重应力之比进行了数值计算,深入分析了超载和多轴型作用下砂砾路基的工作区深度,发现在标准轴载作用下路床范围比现行规范要加深10~20cm,超载相对于轴型变化对砂砾路基会产生更不利的影响。路基模量对工作区深度有一定影响,但过大的模量对改善路基受力环境并无明显作用,但应该严格满足路基顶面的设计回弹模量。指出压实度指标对于砂砾路基施工质量控制的不适应性,从确保路基抗变形能力和承载能力的基本功能的角度,建立了基于路基横断面关键点沉降差和FWD线性反演模量的双指标控制法及相应标准,并对反演的动态模量和承载板测定的静态回弹模量进行了分析比较,提出便于砂砾路基施工应用的模量修正系数。

This paper discusses the geotechnical parameters and strength performance of gravel subgrade stuffing in low filling and shallow excavation section. According to the characteristics of loose material, the ratio of additional load stress to dead weight stress of subgrade is calculated numerically based on ABAQUS finite element software. The working area depth of gravel subgrade under overload and multi-axis loading is analyzed in depth. It is found that the range of subgrade under standard axle load is 10~20 cm deeper than that under current specification, and the overload will have more adverse effect on the gravel subgrade than the change of axle shape. The modulus of subgrade has a certain effect on the depth of working area, but too large modulus has no obvious effect on improving the subgrade stress environment, but it should strictly meet the design modulus of resilience of the top surface of subgrade. This paper points out that the compactness index is not suitable for the quality control of gravel subgrade construction. From the viewpoint of ensuring the basic functions of subgrade deformation resistance and bearing capacity, a double-index control method and corresponding standards based on settlement difference of key points in subgrade cross-section and FWD linear inversion modulus are established. The dynamic inversion modulus and the static resilience modulus measured by the bearing plate are analyzed and compared. This paper puts forward the modulus correction coefficient convenient for the application in the construction of gravel subgrade.