【作者】 张伟民；

【导师】 黎福海； 周冠东；

【作者基本信息】 湖南大学 ， 电子与通信工程， 2008， 硕士

【摘要】 近年来,我国交通运输事业有了很大发展,公路及铁路的交通密度和负荷量日益增大,对交通建设的工程质量和进度均提出了新的更高要求。在道路施工中,以科学、合理的方法对路基填筑质量进行检测和监控是保证路基安全、保障正常施工的重要措施。通常的做法是,以路基密实度作为判断路基质量的指标。但这种方法有其明显的局限性:因为即使路基密实度相同,不同环境、不同条件下不同路基的力学性能指标仍可能有较大差异。所以,当前国内外更有代表性的做法是,在检测路基密实度的基础上,将路基的动态弹性模量作为反映路基承载力的压实标准。传统的强度及变形参数指标通过静态平板载荷试验测得,即检测路基系数K30。而路基实际承受的荷载不仅有静荷载,还有施工及车辆行驶对路基产生的动荷载。特别是施工中的高速公路或铁路,路基的稳定性和变形问题主要是由于动荷载引起的。所以,采用对路基的动态冲击产生的动应力及动应变指标作为路基填筑质量检测标准,是更为科学、合理的。本文从工程应用实际要求出发,以突出便携式和非破坏性特点,设计研制了便携式落锤弯沉测试仪,通过一个落锤撞击路基来模拟路基所受到的动态受力情况,测得路基表面上的垂直位移和压力,再根据测量数据计算出路基的动态弹性模量,对路基的填筑质量进行评估。本文分析便携式落锤弯沉测试仪的工作原理,着重介绍了仪器的硬件设计和软件设计。硬件设计包括传感器选型、小信号放大和采集、数据传输方式选择,根据便携式应用特点设计电源管理方案。软件设计重点是对采集数据进行数字信号处理的实现,提取真实信号并计算动态弹性模量。更多还原

【Abstract】 With great developments on transportation, the density and load of highways and railways are growwing quickly year by year in our country. More and more new requirements are set forth on the quality of the transportation construction projects. While constructing highways or railways, to evaluate and monitor the filling quality in scientific and effective ways is the most important guarantee to the subgrade quality assurance. In normal construction evaluation, a method is used to calculate the dynamic resilient modulus by means of measuring of the intensity and deformation. The dynamic resilent modulus is therefore taken as the criteria to judge the subgrade compactness. The method has become a trend of the technology development to evaluate the quality of subgrade construction. Traditionally, such characteristics as intensity and deformation of the subgrade are obtained through static plate load testing, i.e. through measuring the subgrade coefficient K30. But actually, the subgrade stands not only the static load but also the dynamic load caused by the heavy traffic. Especially while building the subgrades of highways or railways, the subgrade stability is mainly effected by the dynamic load, as well as the distortion problem is mainly caused by. Therefore, the dynamic stress and dynamic strain index caused by dynamic shock on the subgrade are used as the testing criteria to evaluate the subgrade construction quality.The thesis provides a method to design the Portable Falling Weight Deflectometer, trying to meet the engeneering practical application while emphasizing on such features as portability and non-destructiveness. At first, a falling weight is used to hit the subgrade, simulating the dynamic stress caused by the shock. Secondly, the vertical subsidence and pressure on the surface of the subgrade are measured. Finally, by making use of the measured data, the dynamic resilient modulus is estimated. And consequently, the construction quality of the subgrade is evaluated.The thesis analyses the operating principle of the Protable Falling Weight Deflectometer, emphasizing on the hardware and the software design. The design of hardware includes the selection of sensors, the sampling and amplifying of the small signals, and selecting the modes of data transmission. The power management is specially designed to make the PFWD portable. The design of software highlights the realization of digital signal processing on acquired data, withdrawing of the real signal and estimating of the dynamical resilient modulus.更多还原