重载交通下的路基工作区界定问题探讨

Discussion of the Definition of Subgrade Workspace under Heavy Traffic

通过路面病害调查、有限元路面结构力学计算，分析了重载作用下，路基刚度对我国目前高速与等级路路面结构应力分布的影响与路基应力作用深度。分析表明，重载交通下的路基过大变形是导致高速公路结构疲劳开裂的重要原因之一。等级路的路基甚至地基过大变形是引发路面早期开裂的关键因素之一。在重载作用下，目前的高速与等级路面结构，仍把0～80cm作为路基工作区深度是不够的。路基工作区深度，高速公路应为1．5m，并被现场测试的路基轮载分布深度验证；等级路应为2m，同时应考虑天然地基的变形问题。路基上部60cm石灰土处理起到路基与半刚性底基层之间刚性过渡的作用．也是应对重载、确保路基对路面结构支撑稳定性的有效措施。

According to the investigation of pavement disease and the finite element mechanical calculation of pavement, the influence of subgrade stiffness on stress distribution of pavement structure and stress action depth of subgrade of expressway and grade road were analyzed. It indicates that （ 1 ） the excessive deformation of subgrade under heavy traffic is an important reason of fatigue cracking of expressway pavement; （2） The excessive deformation of subgrade （even foundation） of grade road is a key factor of early pavement cracking. Under heavy traffic, the subgrade workspace of 0 - 80 centimeters deep is not enough to the current pavement of expressway and grade road. The subgrade workspace depth of expressway should be 1.5 meters, which has been proved by the field tested wheel load distribution depth.The subgrade workspace depth of grade road should be 2 meters, and the deformation of natural foundation should be considered at the same time. Dispose the upper subgrade by paving a limestone soil of 60 centimeters deep can transit the stiffness between subgrade and semi-rigid subbase course, and it is also an effective method to resist heavy duty and ensure stability of pavement structure under subgrade bearing.