A testing device and testing method for ground penetrating radar

Abstract

The application discloses a testing device and testing method of a ground penetrating radar, which comprises a base provided with a testing groove, and a simulation device for filling simulated pavement structure and internal defect diseases in the testing groove; the simulation device comprises a pavement surface layer, a pavement base layer, a sand filling body for simulating a roadbed, and different disease body models arranged in the sand filling body; the simulation device can arrange the different disease body models in the sand filling body to form different simulation devices according to testing requirements; and the pavement surface layer and the pavement base layer are detachably assembled with the testing groove. The device can simultaneously satisfy the testing of a ground coupling type radar or an air coupling type radar. The application models the road thickness testing and hidden disease testing of the ground penetrating radar technology, can effectively test the detection capability of the ground penetrating radar for the pavement thickness and pavement defects, achieves the unity, convenience, high efficiency and standardization of the testing process, and is suitable for popularization and application.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of road engineering, in particular to a testing device and testing method of ground penetrating radar, which can be used to test the detection capability of ground penetrating radar for road surface structure layer thickness and internal defects. BACKGROUND

[0002] Ground penetrating radar is an electromagnetic technology that uses radio waves to detect the distribution of underground media and scan invisible targets or underground interfaces to determine their internal structure or position. Its working method and principle are as follows: high-frequency electromagnetic waves are transmitted in the form of a wide-band pulse through a transmitting antenna, reflected or transmitted by the target, and received by a receiving antenna. When high-frequency electromagnetic waves propagate in the medium, their path, electromagnetic field strength and waveform will change with the electrical properties and aggregate form of the medium they pass through. Thus, by collecting, processing and analyzing the time-domain waveform, the spatial position or structure state of the underground interface or target can be determined.

[0003] At present, ground penetrating radar technology is developing rapidly at home and abroad, and there are many equipment manufacturers and equipment models. However, there is a lack of a unified, convenient, efficient and standardized testing device and testing method for radar detection of road surface thickness and radar detection of road surface defects in road engineering. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a testing device and testing method of ground penetrating radar, which can uniformly, conveniently, efficiently and standardize the testing of the detection capability of ground penetrating radar for road surface structure layer thickness and internal defects.

[0005] To solve the above technical problems, the following technical solutions are adopted:

[0006] A testing device of ground penetrating radar is used to test the detection capability of ground penetrating radar for road surface thickness and the detection capability of ground penetrating radar for road surface defects. The testing device comprises a base provided with a test groove, and a simulation device for filling simulated road surface structure and internal defect diseases in the test groove. The simulation device comprises a road surface layer, a road base layer, a sand-filled body simulating a roadbed, and different disease body models placed in the sand-filled body. The simulation device can place different disease body models in the sand-filled body to form different simulation devices according to testing requirements. The road surface layer and the road base layer are detachably assembled with the test groove.

[0007] As a further improvement of the present application, the ground penetrating radar is a ground-coupled radar or an air-coupled radar. A slide rail is provided on the upper surface of the base on one side of the test groove, and a moving frame is installed on the slide rail. An extension end extending above the test groove is provided on the moving frame, and the extension end is used to install an air-coupled antenna.

[0008] Further, one side of the test groove body is in the form of an openable and closable plate, and the base surface of the lower part of the openable and closable plate is downwardly inclined to form a sand unloading sliding surface.

[0009] Further, the pavement surface layer is 5-15 cm, the pavement base layer is 18-30 cm, and the sand-filled body simulating the roadbed is 1.5-2.0 m; and the base is a concrete structure.

[0010] Further, the disease body model includes a cavity model, a void model, a water-rich body model, and a loose body model.

[0011] Further, the test device further comprises a radar wave velocity calibration device.

[0012] Further, the radar wave velocity calibration device comprises a pavement surface layer with a preset thickness and a steel plate at the bottom for calibration; and further comprises a calibration steel plate, which is used to be placed at the bottom of the sand-filled body of the simulated roadbed without the internal disease body model during calibration.

[0013] The application further provides a test method of the ground penetrating radar, which tests the road surface thickness detection capability and the road surface defect detection capability of the ground penetrating radar by using the test device of the ground penetrating radar, and comprises the following steps:

[0014] (1) Radar wave velocity calibration:

[0015] a first radar calibration wave velocity V1 is obtained, which is used for road surface thickness detection capability test;

[0016] a second radar calibration wave velocity V2 is obtained, which is used for road surface defect detection capability test;

[0017] (2) Road surface thickness test of the ground penetrating radar:

[0018] the pavement surface layer of a specified sample is detected by using the ground penetrating radar, and the measured thickness h1' of the sample pavement surface layer is calculated by using the first radar calibration wave velocity V1 and the radar measured two-way travel time t1';

[0019] h1'=V1 t1' / 2

[0020] the measured thickness h1' is compared with the actual thickness of the specified sample to determine whether the road surface thickness detection capability is accurate;

[0021] (3) Road surface defect test of the ground penetrating radar:

[0022] a disease body model of a specified type, buried depth and size is detected by using the ground penetrating radar, the measured buried depth h2' of the disease body model is calculated by using the second radar calibration wave velocity V2 and the radar measured two-way travel time t2', and the type and planar size of the disease body are determined by the corresponding atlas features in the specification;

[0023] h2' = V2 t2' / 2

[0024] According to the comparison of the measured buried depth h2', the characteristic map, the plane size and the corresponding parameters of the actual disease body model, whether the road defect detection capability is accurate is judged.

[0025] Further, in the step (1):

[0026] The first radar calibration wave speed V1 is obtained by selecting a preset thickness of a road surface layer structure with a steel plate at the bottom for radar wave speed calibration to obtain the first radar wave speed V1.

[0027] The second radar calibration wave speed V2 is obtained by adding a steel plate at the bottom of the test groove, and then sequentially laying a sand filling structure, a road base structure and a road surface layer structure of the simulated roadbed without disease bodies on the steel plate; radar wave speed calibration is performed to obtain the second radar wave speed V2.

[0028] By adopting the above technical scheme, the present application has at least the following advantages:

[0029] 1. The test device of the ground penetrating radar proposed in the present application models the road thickness test and the hidden disease test of the ground penetrating radar technology, which can effectively test the detection capability of the ground penetrating radar for road thickness and road defects, and achieve unified, convenient, efficient and standardized test process.

[0030] 2. When the radar wave speed is calibrated, the form of adding a steel plate at the bottom can make the radar wave speed calibration more accurate.

[0031] 3. The test device of the present application can be applied to both ground-coupled radar and air-coupled radar, and a special slide rail is provided for the antenna of the air-coupled radar, which is convenient and efficient to operate.

[0032] 4. By forming a hinged plate on one side of the test groove, a sand unloading sliding surface is formed on the downward inclined base surface of the hinged plate, and when the disease body model is replaced, the sand can directly slide down, which is convenient for sand unloading.

[0033] 5. The present application adopts the form of first radar wave speed calibration, and then replacement of the simulation device according to different test requirements, which is accurate and comprehensive in test results. BRIEF DESCRIPTION OF DRAWINGS

[0034] The above is only a summary of the technical scheme of the present application, in order to more clearly understand the technical means of the present application, the following will further explain the present application in detail combined with the drawings and specific embodiments.

[0035] Figure 1 is a side view structural schematic diagram of the test device of the ground penetrating radar in an embodiment of the present application;

[0036] Figure 2 is Figure 1 is a top view structural schematic diagram of a test device of a ground penetrating radar;

[0037] Figure 3 is Figure 2 is a partial enlarged schematic view of the intermediate portion;

[0038] Figure 4 is Figure 1 is a front view structural schematic diagram of a test device of a ground penetrating radar;

[0039] Figure 5 is Figure 4 is a partial enlarged schematic view of the intermediate portion;

[0040] Figure 6 is a hollow model schematic diagram;

[0041] Figure 7 is a void model schematic diagram;

[0042] Figure 8 is a water-rich body model schematic diagram;

[0043] Figure 9 is a loose body model schematic diagram. DETAILED DESCRIPTION

[0044] The present application designs and develops a set of test devices of a ground penetrating radar, to test the road surface thickness detection capability and the road surface defect detection capability of the ground penetrating radar. The test mechanism of the test device is: through establishing a road site model with hidden diseases, the detection performance of the ground penetrating radar is tested, and through a specially designed device, the switching of the two simulated environments of radar thickness measurement and radar defect measurement is realized, to realize convenience and efficiency.

[0045] Based on the above test mechanism, in combination with Figures 1-5 , the embodiment provides a test device of a ground penetrating radar, which comprises a base 1, the base 1 is provided with a test groove body 11, and a simulation device 2 for filling simulated road surface structure and internal defect disease is arranged in the test groove body 11; the simulation device 2 comprises a road surface surface layer 21, a road surface base layer 22, a sand filling body 23 for simulating a road bed and different disease body models 24 arranged in the sand filling body 23; the simulation device 2 can arrange different disease body models in the sand filling body to form different simulation devices according to test requirements; and the road surface surface layer 21 and the road surface base layer 22 are detachably assembled with the test groove body 11, wherein the road surface surface layer 21 and the road surface base layer 22 are arranged in a detachable assembly form as a whole.

[0046] The device preferably simultaneously satisfies the test work of the performance of the coupled radar and the uncoupled radar antenna, and a sliding rail 3 is arranged on the upper surface of the base 1 on one side of the test groove 11, a moving frame 4 is arranged on the sliding rail 3, an extension end 41 extending to the upper side of the test groove 11 is arranged on the moving frame 4, and the uncoupled antenna 5 is arranged on the extension end 41, so as to detect the test area through the uncoupled antenna.

[0047] The test area in the test groove 11 should simulate the actual situation of the road site as much as possible, and generally, a 5-15 cm thick pavement surface layer 21 and an 18-30 cm thick pavement base layer 22 are arranged, the pavement surface layer 21 and the pavement base layer 22 are detachable assemblies, a 1.5-2.0 m thick sand filling body 23 is arranged below to simulate the roadbed, and in addition, a cavity model 241 Figure 6 ), a void model 242 Figure 7 ), a water-rich body model 243 Figure 8 ) and a loose body model 244 Figure 9 ) can be designed according to the test requirements, and these different types of entity models are buried in the sand filling body 23 according to different depths and different sizes according to actual requirements. The base 1 is poured with concrete. At the same time, one side of the test groove 11 is preferably provided with a openable and closable plate 6, and the surface of the base 1 below the openable and closable plate 6 is downwardly inclined to form a sand discharging sliding surface.

[0048] The internal defects of the road are simulated as follows:

[0049] ① Cavity model

[0050] First, part of the sand is filled to the specified depth of the model, the cavity model is placed at the specified position (such as Figure 6 ), and then the remaining sand is poured into the device, so that the cavity model is buried in the sand filling body, and the upper surface of the sand should be in close contact with the interface of the pavement base layer without leaving gaps.

[0051] ② Void model

[0052] First, part of the sand is filled to the specified depth of the model, the void model is placed at the specified position below the pavement base layer (such as Figure 7 ), and then the remaining sand is poured into the device, so that the void model is buried in the sand filling body, and the upper surface of the sand should be in close contact with the interface of the pavement base layer without leaving gaps.

[0053] ③ Water-rich body model

[0054] First, part of the sand is filled to the specified depth of the model, the water-rich body model filled with water is placed at the specified position (such as Figure 8 ), and then the remaining sand is poured into the device, so that the water-rich body model is buried in the sand filling body, and the upper surface of the sand should be in close contact with the interface of the pavement base layer without leaving gaps.

[0055] IV. Loose body model

[0056] First, fill part of the sand to the specified depth of the model, place the loose body model at the specified position (such as Figure 9 ), and then pour the remaining sand into the device so that the loose body model is buried inside the sand-filled body, and the upper surface of the sand-filled body should be in close contact with the road base interface without any gap.

[0057] The above test device can simulate the actual situation of the road site according to the test requirements. In order to test accurately, the above test device further comprises a radar wave speed calibration device. The radar wave speed calibration device comprises a pre-set thickness of a bottom steel plate, a calibration road surface layer; and further comprises a calibration steel plate, which is used to be placed at the bottom of the sand-filled body of the simulated roadbed without internal disease body model during calibration.

[0058] The test method of the above test device is as follows:

[0059] (1) Radar wave speed calibration:

[0060] A: Obtain the first radar calibration wave speed V1 for the road surface thickness detection capability test; specifically:

[0061] Select a road surface layer sample with a pre-set thickness h1 (bottom layer with steel plate), use radar for sampling test, record the time difference t1 of direct wave signal and sample bottom reflection wave signal (t is double travel time), and the actual propagation path length h of radar.

[0062]

[0063] Δx is 1 / 2 distance between the transmitting end and the receiving end, according to the actual situation, Δx is approximately 0, then the first radar calibration wave speed V1 is:

[0064] V1 = 2h1 / t1

[0065] B, obtain the second radar calibration wave speed V2 for the road surface defect detection capability test; specifically:

[0066] Select a roadbed road surface sample with a pre-set thickness h2 (bottom layer with steel plate) (add a steel plate at the bottom of the test tank, and then add a sand-filled body of the simulated roadbed without disease body, road base and road surface layer on the steel plate in turn), use radar for sampling test, record the time difference t2 of the peak of direct wave signal and the peak of sample bottom reflection wave (t is double travel time). Then the radar wave speed V2 is:

[0067] V2 = 2h2 / t2

[0068] (2) Ground penetrating radar road thickness test:

[0069] The ground penetrating radar is used to detect the pavement surface layer of a specified sample, and the measured thickness h1' of the sample pavement surface layer is calculated by the first radar calibrated wave velocity V1 and the radar measured two-way travel time t1';

[0070] h1' = V1 t1' / 2

[0071] According to the comparison between the measured thickness h1' and the actual thickness of the specified sample, it is determined whether the pavement thickness detection capability is accurate or not;

[0072] (3) Ground penetrating radar pavement defect test:

[0073] The ground penetrating radar is used to detect a specified type, buried depth and size of a disease body model (such as Figures 6-9 ), and the measured buried depth h2' of the disease body model is calculated by the second radar calibrated wave velocity V2 and the radar measured two-way travel time t2'; the type and planar size of the disease body are determined by the corresponding atlas features in the specification;

[0074] h2' = V2 t2' / 2

[0075] According to the comparison between the measured buried depth h2', the characteristic atlas, the planar size and the corresponding parameters of the actual disease body model, it is determined whether the pavement defect detection capability is accurate or not.

[0076] According to the “Technical Standard for Comprehensive Detection and Risk Assessment of Urban Underground Disease Bodies” (JGJ 437-2018), the atlas specification is as follows.

[0077] Table 1: Typical disease radar atlas features

[0078]

[0079]

[0080] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Those skilled in the art can make some simple modifications, equivalent changes or modifications by using the disclosed technical content, which falls within the protection scope of the present application.

Claims

1. A testing method for ground-penetrating radar, characterized in that, The testing equipment for ground-penetrating radar was used to test the ground-penetrating radar's ability to detect road surface thickness and road surface defects. The ground-penetrating radar testing device includes a base with a test tank, and the test tank is used to fill a simulation device that simulates road surface structure and internal defects. The simulation device includes a road surface layer, a road base layer, a sand-filled body simulating a roadbed, and different disease models placed in the sand-filled body. The simulation device can be configured by placing different disease models in the sand-filled body to form different simulation devices according to testing requirements. The road surface layer and road base layer are detachably assembled with the test tank. A slide rail is provided on the upper surface of the base on one side of the test tank. A movable frame is installed on the slide rail. An extension end is provided on the movable frame, which extends upward toward the test tank. The extension end is used to install an air-coupled antenna. One side of the test tank is in the form of an openable plate, and the base surface at the bottom of the openable plate is inclined downward to form a sand unloading sliding surface. The testing method includes: (1) Radar beam velocity calibration: The first radar calibration wave velocity V1 is obtained for road thickness detection capability testing. The first radar calibration wave velocity V1 is obtained by selecting a road surface structure with a preset thickness and a steel plate at the bottom for radar wave velocity calibration to obtain the first radar calibration wave velocity V1. The second radar calibration wave velocity V2 was obtained for testing the road surface defect detection capability. The method for obtaining the second radar calibration wave velocity V2 was as follows: a steel plate was laid at the bottom of the test tank, and then a sand-filled structure, a road base structure, and a road surface structure without defects were laid on the steel plate in sequence; radar wave velocity calibration was performed to obtain the second radar calibration wave velocity V2. (2) Ground penetrating radar road surface thickness test: Ground penetrating radar is used to detect the surface layer of a specified sample road surface. The measured thickness h1' of the sample road surface layer is calculated by using the first radar calibration wave velocity V1 and the radar measured two-way travel time t1'. h1'=V1t1' / 2 The accuracy of its pavement thickness detection capability is determined by comparing the measured thickness h1' with the actual thickness of the specified sample. (3) Ground penetrating radar road surface defect test: Ground penetrating radar is used to detect the disease model of specified type, burial depth and size. The actual burial depth h2' of the disease model is calculated by the second radar calibrated wave velocity V2 and the radar measured two-way travel time t2'. The type and planar size of the disease are determined by the corresponding map features of each disease in the map specification of the "Technical Standard for Comprehensive Detection and Risk Assessment of Urban Underground Diseases" JGJ437-2018. h2'=V2t2' / 2 The accuracy of its pavement defect detection capability is determined by comparing the measured burial depth h2', feature map, planar dimensions, and corresponding parameters of the actual defect model.

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