基于探地雷达的机场跑道基层压实度自动检测研究

程利力

摘  要

随着我国基础设施建设的快速发展，机场投资建设的需求量逐渐增大。跑道基层施工作为机场建设过程中的重要环节之一，压实质量不足会大大削弱结构的强度和承载力，给飞机的正常起降造成不可预估的影响。然而，目前压实质量检测仍以传统的环刀法、灌砂法等人工有损检测方法为主，检测过程耗时费力且会破坏跑道基层材料，同时工程中常采用的随机有限抽样检测无法有效地反映整个施工区域的压实质量。针对以上问题，本文构建了表征压实度时空分布特性的约束随机场模型，并提出了利用探地雷达信号分析进行压实度自动检测的方法，主要工作内容如下：

首先，本文对跑道基层材料的压实机理进行分析，研究了压实度影响因素以及不同位置和不同碾压遍数下压实度的时空分布特性，提出了基于有限工程检测数据表征压实度时空分布特性的约束随机场模型，进而有效地反映跑道基层实验段整体压实质量。然后，基于探地雷达对跑道基层材料不同压实度的介电特性进行分析，结果显示：不同基层材料和不同碾压遍数下压实度与相对介电常数具有较好的相关性，相关系数为0.599。接着，利用探地雷达信号进行希尔伯特黄变换，分析了不同探地雷达信号分析指标与压实度的相关性，研究结果表明：峰值系数指标对压实度表征效果最佳，相关系数为0.734，进而可通过对探地雷达信号分析实现压实度自动检测。最后，基于某机场跑道工程案例，对采集的探地雷达信号进行希尔伯特黄变换分析，验证了峰值系数指标可用于跑道基层材料压实度预测，其平均误差率为4.03%，同时基于探地雷达信号分析扩大压实度检测样本数量，生成了相应的压实质量评价云图。

研究表明，本文提出的约束随机场模型能在一定程度上表征不同位置和不同碾压遍数压实度的时空分布特性，同时利用探地雷达信号分析方法可以实现压实度自动检测，大大缩短施工过程中检测用时，进而为施工过程中碾压遍数以及压实不足区域的确定提供一定的参考。

关键词：机场跑道基层；压实度；时空分布；约束随机场；探地雷达；希尔伯特黄变换

Abstract

With the rapid development of infrastructure construction in China, the demand for airport investment and construction is gradually increased. The runway base construction is one of the important links in the airport construction process. Insufficient compaction quality will greatly weaken the strength and bearing capacity of the structure, causing unpredictable effects on the normal take-off and landing of aircraft. However, the compaction quality detection is still dominated by the traditional cutting ring method, sand replacement method and other manual destructive detection methods, which are time-consuming and laborious, and will damage the runway base materials. Meanwhile, the random limited sampling detection results used in the project cannot effectively reflect the compaction quality of the whole construction area. To solve the above problems, a conditional random field model representing the time and space distribution characteristics of compaction degree is constructed in this study, and a method of compaction degree automatic detection using ground penetrating radar (GPR) signal analysis is proposed. The main research contents are as follows:

Firstly, this thesis analyzes the compaction mechanism of the runway base material, and studies the influencing factors of compaction degree and the time-space distribution characteristics in different position and various rolling passes. A conditional random field model based on finite engineering testing data to characterize the time and space distribution of compaction degree is proposed, which effectively reflects the runway experimental area compaction quality as a whole. Then, the dielectric properties of different compaction degree of runway base materials are analyzed using GPR. The compaction degree and the relative permittivity have a good correlation under different base materials and different rolling passes, and the correlation coefficient is 0.599. Secondly, the Hilbert-Huang transform of GPR signal is used to analyze the correlation between different GPR signal analysis indexes and compaction degree. The results show that the crest factor index is the best effect on the characterization of the compaction degree, and the correlation coefficient is 0.734, and the compaction degree is automatically detected by the GPR signal analysis. Finally, based on the runway engineering case of an airport flight area, through the Hilbert-Huang transform analysis of GPR signals collected, it is verified that the crest factor index can be used to evaluate the compaction degree of runway base materials, with an average error rate of 4.03%. At the same time, based on the analysis of GPR, the number of samples for compaction degree detection is expanded, and the corresponding compaction quality cloud map is generated.

The results show that the conditional random field model proposed in this thesis can characterize the time and space distribution characteristics of the compaction degree at different positions and different rolling passes to a certain extent. At the same time, the GPR signal analysis method can realize the automatic detection of the compaction degree, which greatly shortens the detection time in the construction process. Furthermore, it provides a certain reference for the determination of rolling passes and the insufficient compaction area.

Keywords: runway base, compaction degree, time and space distribution, conditional random field, ground penetrating radar, Hilbert-Huang transform