Application Of Fiber Bragg Grating Sensor In The Monitoring Of Subgrade By Impact Rolling

The compaction degree of subgrade is very important to a pavement's comfortability and service life. At present, impact rolling has become one of the most widely used method in reinforcing filled foundation. As more and more scholars are devoted to the theoretical study of the foundation's mechanical response caused by impact rolling, practical field test measurements are exigent to be further improved to verify and guide the theoretical findings. Currently, the selection of the appropriate loose thickness of filler material and proper impact rolling times is most commonly performed by a combination of empirical classification and design, which is likely to result in a waste of resources or a failure to meet the subgrade compaction standard. Therefore, we need to find a stable and reliable method which can monitor the dynamic responses and changes of subgrade under impact rolling compaction effectively to ensure the compactness and guide the road construction correctly.Fiber Bragg Grating(FBG) sensing technology with strong adaptability and high sensitivity provides a new method for the real-time dynamic monitoring, which can completely satisfy the requirements in subgrade compaction. In accordance with features of the subgrade's actual working environment, geogrid is used as the packaging materials of the FBG sensor in this paper.And its production process is introduced detailly. It can not only protect FBG effectively, but also deform in coordination with the subgrade, so we can get experimental data with upper reliability and precision.The data is collected by the FBG sensors embedded in the subgrade during the process of subgrade compaction by impact rolling in the highway from Shenyang to Siping. After analyzing the collected data, we find that geogrid packing FBG sensor is sensitive enough to monitor the strains and stresses of the subgrade under moving and impact rolling load for real-time. Besides, FBG sensors can test the impact roller's speed and determine the proper impact rolling times.At last, ABAQUS, a finite element software, is used to simulate the impact rolling process and build a corresponding subgrade mechanics analysis model with proper simplification and assumption based on the actual subgrade structure. After comparing the results of the simulation analysis with the FBG sensor's data, we can draw the conclusion that this encapsulation method is effective and reliable.