PFWD模量控制的路基承载力动力学指标评价方法

针对当前动力学测定路基承载力难以形成统一标准、弯沉控制指标误差较大，无法精准测定的现状，提出基于便携式落锤弯沉仪(portable falling weight deflectometer，PFWD)模量控制的路基承载力动态力学指标评价方法。以冲击荷载作用下弹性半空间体力学模型，对PFWD动静力学测定指标的差异化进行理论分析，有限元数值模拟构建弹性路基土的动应力空间分布，依托工程实际揭示PFWD的检测特性，并提出精准测定方法。结果表明：PFWD的影响范围，深度方向2.5倍的承载板直径，水平方向以承载板圆心2倍直径的圆周；冲击荷载作用下路基土的动应力衰减规律为σz随深度方向衰减，σr呈45°衰减且速度更快；动静力学测试产生误差的根本原因为刚性承载板与路基土的不完全接触及非线弹性特质；PFWD的检测特性为高估路基刚度，但刚度越大动静差异越小；提出动力学指标预测模型，该模型的相关系数高，避免了线性模型对原点的修正，满足高精度检测的同时提高了检测效率。从而建立基于模量控制的快速检测方法与思路，为高速公路路基承载力的动力学精准测定及科学评价提供参考。

Dynamic index evaluation method for subgrade bearing capacity controlled by PFWD modulus

Giving the current situation that it is difficult to form a unified standard for the dynamic determination of subgrade bearing capacity and the deflection control indexes can not be tested measured, a dynamic mechanical index evaluation method for subgrade bearing capacity based on Portable Falling Weight Deflectometer (PFWD) modulus control is proposed. Based on the physical model of the elastic half space under impact load, the difference of dynamic and static mechanical indexes of PFWD is analyzed theoretically, and the spatial distribution of dynamic stress of elastic subgrade soil under impact load is analyzed by the finite element numerical simulation method. The combined detection method of PFWD and BB is used to evaluate the subgrade bearing capacity of supporting projects, reveal the detection characteristics of PFWD, and propose the accurate measurement method Law. The research results show that the influence range of PFWD is 2.5 times the diameter of bearing plate in the depth direction and 2 times the diameter of bearing plate in the horizontal direction. The attenuation rule of dynamic stress of elastic subgrade soil under impact load is that the attenuation direction of σz is the same as that of depth, and the attenuation direction of σr is 45° with faster attenuation speed. The fundamental reasons for the error in dynamic and static mechanical test indexes are the non-linear elastic characteristics and the incomplete contact between the rigid bearing plate and the subgrade soil and. The detection characteristic of PFWD is the overestimation of subgrade stiffness. The greater the stiffness is, the smaller the dynamic and static difference is. A dynamic prediction model with high correlation coefficient is proposed, thus the correction of the linear model to the origin is avoided, and high-precision detection is achived. A rapid detection method and idea based on the modulus control is established, which can provide reference for the dynamic accurate measurement and scientific evaluation ofsubgrade bearing capacity of expressway.