基于FWD的旧路路基模量反算的问题探讨

Study on Problem in Backcalculation of Subgrade Modulus in Old Road

利用实测弯沉数据反算结构层模量是落锤式弯沉仪(FWD)应用于旧混凝土路面结构检测的核心所在。但是,由于路面结构层参数的多元性,路基反演模量有时可能偏离实际。为寻其根源,作者结合成绵高速公路路面检测,采用有限元分析软件ANSYS,建立了路面非线性有限元模型,并在此基础上,以路基下卧刚性层及路基材料非线性为可变参数,对比了4种不同组合情况下的路基反演模量,发现:路基下卧刚性层的深度对检测数据的反演结果有显著影响,而路基土的非线性性质对反演结果影响有限。因此认为,基于FWD检测数据的结构层模量反演时,可以将路基近似为线弹性体。

The using of measured surface deflections to determine Young＇ s modulus of elasticity for pavement material is the essential application of falling weight deflectometer （FWD） to structure eval- uation of old portland cement concrete road. However, because of the diversity of pavement structural pa- rameter, the backcalculation modulus of subgrade may sometimes deviate from the truth. To find out the reason, according to the non-destructive testing （NDT） at Chengdu-Mianyan highway, the author built nonlinear finite element model of pavement by using finite element analysis application ANSYS to simu- late the deflections. The rigid layer underneath subgrade and nonlinear property of soil are two variables in this model. Comparing with four different combinations, backcalculation of subgrade modulus result indicate that the depth of rigid layer has a great impact on backcalculation, while the nonlinear property of soil is insignificant that a linear elastic layer can be used to simulate subgrade.