Research On Non-destructive Testing Methods And Applications Of Highway Subgrade Diseases Based On Electrical Resistivity Tomography

With the vigorous development of the national economy and the increasingly improved construction of highways,the maintenance and healthy operation of our country’s expressways have become particularly important.The highway subgrade is an integral part of the road structure’s load-bearing capacity.Therefore,strengthening the detection and identification of diseases in highway subgrades is of great significance for enhancing the operational safety and service life of expressways.The highway subgrade is a concealed engineering project,and the refined characterization of the subgrade structure is a prerequisite for achieving non-destructive testing of the subgrade.Compared to traditional detection methods,high-density electrical methods in geophysics can effectively identify the electrical differences in subgrade layers and different types of diseases,accurately delineating the regions and development characteristics of subgrade diseases on highways.The non-destructive testing methods and application research of highway subgrade diseases based on high-density electrical methods are systematically explored in this paper.The main research contents and achievements are as follows:(1)Based on the electrical differences of the subgrade structure layer and different types of diseases in expressways,and addressing the issues of cumbersome modeling process,difficulty in batch processing and quick comparison,and insufficient automation in conventional numerical simulation methods of high-density electrical methods,adaptive improvements were made using the Python programming tools to the open-source software Gmsh and Res IPy.A series of visualization software suitable for modeling subgrade diseases in expressways were developed,including parameterized modeling,fast forward and inverse calculations,and automated imaging.This development achieved automated modeling,high-precision calculations,and automated rapid imaging of various types of subgrade disease models.(2)Utilizing the developed software series and combining with the characteristics of expressway subgrade structures,a series of highway subgrade models reflecting different disease types were constructed using both two-dimensional and threedimensional modeling methods.During the model establishment process,variables such as resistivity,burial depth,scale,and quantity of disease regions,as well as the shielding effect of asphalt high-resistance layers,were taken into account.The electrical response characteristics of subgrade models with different disease types were systematically analyzed.The calculation results of the models clarified the identification features of major disease types in highway subgrades,indicating that the rational application of high-density electrical methods can achieve high-precision detection and identification of subgrade diseases.(3)The method was applied to non-destructive testing of three sections with disease-prone areas on expressways.The electrode grounding was achieved through the coupling with moist soil.By combining the measured high-density electrical data with drilling information and using forward and inverse numerical calculations,a geoelectric model of the in-service highway subgrade structure layer was established,and the main areas of disease development were delineated.High-density electrical methods can accurately reflect the overall electrical characteristics of highway subgrades,aiding in precise localization and identification of potential disease areas.This technique can provide technical references for subsequent highway maintenance and health monitoring activities.