Determining the condition of a concrete structure using electromagnetic signals

• US 6,429,802 B1
• Filed: 12/08/1999
• Issued: 08/06/2002
• Est. Priority Date: 12/08/1998
• Status: Expired due to Fees

• Current Assignee: Geophysical Survey Systems, Inc.
• Original Assignee: Geophysical Survey Systems, Inc.
• Inventors: Roberts, Roger L.
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US09/457,749
• Time in Patent Office: 972 Days
• Field of Search: 342/21, 342/22, 342/25, 342/118, 342/127, 342/134-136, 342/175, 342/176, 342/179, 342/188-197, 342/59, 342/27, 342/28
• US Class Current: 342/22
• CPC Class Codes: G01S 13/885 for ground probing prospecting or detecting using electromagnetic waves G01V3/12
• CPC Class Codes: G01S 7/41 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G01V 3/12 operating with electromagnetic waves operating with millimetre waves G01V8/005

Abstract

Ground penetrating radar (GPR) is a technique that may be used to image the inside of a structure by collecting the echoes (or reflections) resulting from electromagnetic signals such as, for example, electromagnetic waves of typically high frequency, being radiated into the structure. Typically, the rebars inside of a reinforced concrete structure are strong radar wave reflectors. Locating deteriorated areas within a reinforced concrete structure may be accomplished by analyzing the reflections, particularly the amplitudes of the reflections, from the rebars in the reinforced concrete structure. Furthermore, the extent of deterioration of these located areas may be determined from such analysis. Significantly, the system and method described herein, when applied to determine the extent of deterioration of one or more areas of a reinforced concrete bridge deck, is effective even if a layer of asphalt is laminated to the surface of the reinforced bridge deck. A method and system for determining a condition of a substantially concrete structure is provided. One or more computer-readable data signals is received, where each data signal represents an electromagnetic signal detected from an area of the concrete structure. One or more of the detected electromagnetic signals include electromagnetic energy reflected from the concrete structure as a result of an electromagnetic signal transmitted into the concrete structure. An extent of deterioration of one or more areas of the substantially concrete structure are determined from the one or more computer-readable data signals.

Claims

1. A method of determining a condition of a substantially concrete structure, the method comprising:

receiving one or more computer-readable data signals, wherein each data signal represents an electromagnetic signal detected from an area of the concrete structure, and wherein one or more of the detected electromagnetic signals include electromagnetic energy reflected from the concrete structure as a result of an electromagnetic signal transmitted into the concrete structure; and

determining from the one or more computer-readable data signals an extent of deterioration of one or more areas of the substantially concrete structure.

2. The method of claim 1, wherein the step of determining includes:

selecting one or more of the data signals;

determining an amplitude of each selected data signal; and

determining the extent of deterioration of the one or more areas from the determined amplitudes.

3. The method of claim 2, wherein the substantially concrete structure contains one or more reinforcing bars, and each selected data signal corresponds to one of the one or more reinforcing bars, and wherein the determined amplitude of each selected signal is an amplitude resulting from electromagnetic energy reflected from the corresponding reinforcing bar.

4. The method of claim 3, wherein the substantially concrete structure has a first side, each transmitted electromagnetic signal having been transmitted at a different position along the first side of the concrete structure, wherein each data signal represents an electromagnetic signal collected over a period of time, the method further comprising:

for each data signal, selecting a time interval of the data signal during which the electromagnetic energy reflected from the corresponding reinforcing bar was detected; and

for each data signal, determining a peak amplitude of the data signal during the selected time interval,

wherein determining an amplitude includes, for one or more spatial intervals of a first length along the first side of the substantially concrete structure, selecting a data

wherein determining an amplitude includes, for one or more spatial intervals of a first length along the first side of the substantially concrete structure, selecting a data signal with a peak amplitude of a highest magnitude from among data signals corresponding to electromagnetic signals transmitted within the spatial interval.

5. The method of claim 4, further comprising:

migrating the data signals to facilitate selecting the data signal with a peak amplitude of the highest magnitude.

6. The method of claim 2, wherein the substantially concrete structure has a first side from which the transmitted and detected electromagnetic signals are transmitted and detected, respectively, and wherein determining the extent of deterioration of the one or more areas from the determined amplitudes:

for each determined amplitude, adjusting the determined amplitude to accommodate for attenuation of the selected signal due to a distance of the corresponding reinforcing bar from the first side; and

determining the extent of deterioration of the one or more areas from the adjusted amplitudes.

7. The method of claim 2, wherein, for each determined amplitude, the determined amplitude is inversely related to an extent of deterioration of the area of the concrete structure corresponding to the data signal from which the determined amplitude was determined.

8. The method of claim 2, wherein the substantially concrete structure has a first side, and determining the extent of deterioration of the one or more areas from the determined amplitudes includes:

for each determined amplitude, determining a coordinate of the determined amplitude on a two-dimensional representation of the first side;

displaying the two-dimensional representation of the first side of the substantially concrete structure, wherein each determined amplitude is represented at the determined coordinate with a value corresponding to the determined amplitude; and

determining the extent of deterioration of the one or more areas by visually inspecting the two-dimensional representation.

9. The method of claim 8, wherein each determined amplitude is represented in the two-dimensional representation as a color or grayscale value.

10. The method of claim 1, wherein the data signals include one or more first data signals corresponding to electromagnetic energy having an electric field polarized primarily in the first direction and one or more second data signals corresponding to electromagnetic energy having an electric field polarized primarily in the second direction substantially orthogonal to the first direction, wherein each first data signal has an associated second data signal detected from substantially a same area as the first data signal, and wherein the step of determining includes:

for each first data signal, subtracting from the first data signal the associated second data signal to produce a third signal; and

determining the extent of deterioration of the one or more areas from the third signal.

11. The method of claim 10, wherein the step of determining further includes:

determining an amplitude of each selected signal; and

determining the extent of deterioration of the one or more areas from the determined amplitudes.

12. The method of claim 11, wherein the substantially concrete structure contains one or more reinforcing bars, and wherein the determined amplitude of each selected third signal is an amplitude resulting from electromagnetic energy reflected from one or more of the one or more reinforcing bars.

13. The method of claim 12, wherein the substantially concrete structure has a first side, each transmitted electromagnetic signal having been transmitted at a different position along the first side of the concrete structure, wherein each data signal represents an electromagnetic signal collected over a period of time, and wherein, for each third signal, the method further comprises:

selecting a time interval of the third signal during which the electromagnetic energy reflected from the one or more corresponding reinforcing bars was detected; and

determining a peak amplitude of the data signal during the selected time interval,

wherein the extent of deterioration of the one or more areas is determined from the peak amplitudes.

14. The method of claim 11, wherein the substantially concrete structure has a first side from which the transmitted and detected electromagnetic signals are transmitted and detected, respectively, and wherein the substantially concrete structure contains one or more reinforcing bars, and wherein each determined amplitude corresponds to reflections of electromagnetic energy from one or more of the one or more reinforcing bars, wherein the step of determining the extent of deterioration of one or more areas of the concrete structure from the amplitudes includes:

for each determined amplitude, adjusting the determined amplitude to accommodate for attenuation of the detected signals from which the determined amplitude is determined due to a distance of the one or more corresponding reinforcing bars from the first side; and

determining the extent of deterioration of the one or more areas from the adjusted amplitudes.

15. The method of claim 11, wherein, for each determined amplitude, the determined amplitude is inversely related to an extent of deterioration of the area of the concrete structure corresponding to the data signals from which the determined amplitude was determined.

16. The method of claim 11, wherein the substantially concrete structure has a first side, and the step of determining the extent of deterioration of the one or more areas from the determined amplitudes includes:

for each determined amplitude, determining a coordinate of the determined amplitude on a two-dimensional representation of the first side;

displaying the two-dimensional representation of the first side of the substantially concrete structure, wherein each determined amplitude is represented at the determined coordinate with a value corresponding to the determined amplitude; and

determining the extent of deterioration of the one or more areas by visually inspecting the two-dimensional representation.

17. The method of claim 16, wherein each determined amplitude is represented in the two-dimensional representation as a color or grayscale value.

18. The method of claim 1, wherein step of determining includes:

removing from each data signal data representing electromagnetic signals not reflected from the substantially concrete structure; and

determining from remaining data of the data signals whether one or more areas of deterioration are present within the substantially concrete structure.

19. The method of claim 18, wherein at least a first side of the substantially concrete structure is adjacent to one or more layers of material, and the transmitted signal is transmitted through the one or more layers, and wherein the step of removing includes:

removing, from each data signal, data representing electromagnetic signals reflected from the one or more layers.

20. The method of claim 1, further comprising:

transmitting one or more of the electromagnetic signals into the concrete structure that result in the reflected electromagnetic energy.

21. A system of determining the condition of a substantially concrete structure, the system comprising:

means for receiving one or more computer-readable data signals, wherein each data signal represents an electromagnetic signal detected from an area of the concrete structure, and wherein one or more of the detected electromagnetic signals include electromagnetic energy reflected from the concrete structure as a result of an electromagnetic signal transmitted into the concrete structure; and

means for determining from the one or more computer-readable data signals an extent of deterioration of one or more areas of the substantially concrete structure.

22. The system of claim 21, wherein the means for determining includes:

means for selecting one or more of the data signals;

means for determining an amplitude of each selected data signal; and

means for determining the extent of deterioration of the one or more areas from the determined amplitudes.

23. The system of claim 22, wherein the substantially concrete structure contains one or more reinforcing bars, and each selected data signal corresponds to one of the one or more reinforcing bars, and wherein the determined amplitude of each selected signal is an amplitude resulting from electromagnetic energy reflected from the corresponding reinforcing bar.

24. The system of claim 23, wherein the substantially concrete structure has a first side, each transmitted electromagnetic signal having been transmitted at a different position along the first side of the concrete structure, wherein each data signal represents an electromagnetic signal collected over a period of time, the system further comprising:

means for selecting, for each data signal, a time interval of the data signal during which the electromagnetic energy reflected from the corresponding reinforcing bar was detected; and

means for determining, for each data signal, a peak amplitude of the data signal during the selected time interval,

wherein the means for determining an amplitude includes, for one or more spatial intervals of a first length along the first side of the substantially concrete structure, means for selecting a data signal with a peak amplitude of a highest magnitude from among data signals corresponding to electromagnetic signals transmitted within the spatial interval.

25. The system of claim 24, further comprising:

means for migrating the data signals to facilitate selecting the data signal with a peak amplitude of the highest magnitude.

26. The system of claim 22, wherein the substantially concrete structure has a first side from which the transmitted and detected electromagnetic signals are transmitted and detected, respectively, and wherein the means for determining from the amplitudes includes:

means for adjusting, for each determined amplitude, the determined amplitude to accommodate for attenuation of the selected signal due to a distance of the corresponding reinforcing bar from the first side; and

means for determining the extent of deterioration of the one or more areas from the adjusted amplitudes.

27. The system of claim 22, wherein, for each determined amplitude, the determined amplitude is inversely related to an extent of deterioration of the area of the concrete structure corresponding to the data signal from which the determined amplitude was determined.

28. The system of claim 22, wherein the substantially concrete structure has a first side, and the means for determining the extent of deterioration of the one or more areas from the determined amplitudes includes:

means for determining, for each determined amplitude, a coordinate of the determined amplitude on a two-dimensional representation of the first side;

means for displaying the two-dimensional representation of the first side of the substantially concrete structure, wherein each determined amplitude is represented at the determined coordinate with a value corresponding to the determined amplitude; and

means for determining the extent of deterioration of the one or more areas by visually inspecting the two-dimensional representation.

29. The system of claim 28, wherein each determined amplitude is represented in the two-dimensional representation as a color or grayscale value.

30. The system of claim 21, wherein the data signals include one or more first data signals corresponding to electromagnetic energy having an electric field polarized primarily in the first direction and one or more second data signals corresponding to electromagnetic energy having an electric field polarized primarily in the second direction substantially orthogonal to the first direction, wherein each first data signal has an associated second data signal detected from a same area as the first data signal, and wherein the means for determining includes:

means for subtracting, for each first data signal, from the first data signal the associated second data signal to produce a third signal; and

means for determining the extent of deterioration of the one or more areas from the third signal.

31. The system of claim 30, wherein the means for determining further includes:

means for determining an amplitude of each selected signal; and

means for determining the extent of deterioration of the one or more areas from the determined amplitudes.

32. The system of claim 31, wherein the substantially concrete structure contains one or more reinforcing bars, and wherein the determined amplitude of each selected third signal is an amplitude resulting from electromagnetic energy reflected from one or more of the one or more reinforcing bars.

33. The system of claim 32, wherein the substantially concrete structure has a first side, each transmitted electromagnetic signal having been transmitted at a different position along the first side of the concrete structure, wherein each data signal represents an electromagnetic signal collected over a period of time, and wherein, for each third signal, the system further comprises:

means for selecting a time interval of the third signal during which the electromagnetic energy reflected from the one or more corresponding reinforcing bars was detected; and

means for determining a peak amplitude of the data signal during the selected time interval,

wherein the extent of deterioration of the one or more areas is determined from the peak amplitudes.

34. The system of claim 31, wherein the substantially concrete structure has a first side from which the transmitted and detected electromagnetic signals are transmitted and detected, respectively, and wherein the means for determining from the amplitudes includes:

means for adjusting, for each determined amplitude, the determined amplitude to accommodate for attenuation of the detected signals from which the determined amplitude is determined due to a distance of the corresponding reinforcing bar from the first side; and

means for determining the extent of deterioration of the one or more areas from the adjusted amplitudes.

35. The system of claim 31, wherein, for each determined amplitude, the determined amplitude is inversely related to an extent of deterioration of the area of the concrete structure corresponding to the data signals from which the determined amplitude was determined.

36. The system of claim 31, wherein the substantially concrete structure has a first side, and the means for determining the extent of deterioration of the one or more areas from the determined amplitudes includes:

means for determining, for each determined amplitude, a coordinate of the determined amplitude on a two-dimensional representation of the first side;

means for displaying the two-dimensional representation of the first side of the substantially concrete structure, wherein each determined amplitude is represented at the determined coordinate with a value corresponding to the determined amplitude; and

means for determining the extent of deterioration of the one or more areas by visually inspecting the two-dimensional representation.

37. The system of claim 36, wherein each determined amplitude is represented in the two-dimensional representation as a color or grayscale value.

38. The system of claim 21, wherein the means for determining includes:

means for removing from each data signal data representing electromagnetic signals not reflected from the substantially concrete structure; and

means for determining from remaining data of the data signals whether one or more areas of deterioration are present within the substantially concrete structure.

39. The system of claim 38, wherein at least a first side of the substantially concrete structure is adjacent to one or more layers of material, and the transmitted signal is transmitted through the one or more layers, and wherein the means for removing includes:

means for removing, from each data signal, data representing electromagnetic signals reflected from the one or more layers.

40. The system of claim 21, further comprising:

means for transmitting one or more of the electromagnetic signals into the concrete structure that result in the reflected electromagnetic energy.

41. A system for determining the condition of a substantially concrete structure, the system comprising:

a computer-readable storage medium to store one or more computer-readable data signals, wherein each data signal represents an electromagnetic signal detected from the concrete structure and one or more of the detected electromagnetic signals include electromagnetic energy reflected from an area within the concrete structure as a result of an electromagnetic signal transmitted into the concrete structure;

a data analysis application to receive the computer-readable data signals and determine from the data signals an extent of deterioration of one or more areas of the substantially concrete structure;

means to read the one or more computer-readable data signals from the computer-readable medium; and

means to execute the data analysis application.

42. The system of claim 41, wherein the data analysis application includes:

a first selection module to receive as input the one or more data signals, select one or more of the one or more data signals, and output the selected signals; and

an amplitude determination module to receive the selected signals, determine an amplitude of each selected data signal, and output the determined amplitudes,

wherein the extent of deterioration of the one or more areas is determined from the determined amplitudes.

43. The system of claim 42, wherein the substantially concrete structure contains one or more reinforcing bars, and each selected data signal corresponds to one of the one or more reinforcing bar, and wherein the determined amplitude of each selected signal is an amplitude resulting from electromagnetic energy reflected from the corresponding reinforcing bar.

44. The system of claim 43, wherein the substantially concrete structure has a first side, each transmitted electromagnetic signal having been transmitted at a different position along the first side of the concrete structure, wherein each data signal represents an electromagnetic signal collected over a period of time, the data analysis module further including:

a time interval selection module to receive the one or more data signals, to select, for each data signal, a time interval of the data signal during which the electromagnetic energy reflected from the corresponding reinforcing bar was detected, and to output the selected time intervals; and

a peak amplitude determination module to receive the one or more data signals, to determine, for each data signal, a peak amplitude of the data signal during the selected time interval, and to output the peak amplitudes,

wherein the first selection module selects, for one or more spatial intervals of a first length along the first side of the substantially concrete structure, a data signal with a peak amplitude of a highest magnitude from among data signals corresponding to electromagnetic signals transmitted within the spatial interval.

45. The system of claim 44, further comprising:

a data migration module to receive the one or more data signals, to migrate the data signals, and to output the migrated signals to the first selection module, wherein the migration of the data signals facilitates the selecting of the data signal with a peak amplitude of the highest magnitude.

46. The system of claim 44, further comprising:

a graphical user interface to receive the one or more data signals and display a representation of the one or more data signals as a function of time with respect to the first side of the concrete structure, to receive one or more first user-selected inputs, each first input indicative of a time interval, and to send each user-selected time interval to the first selection module,

wherein the first selection module selects each selected time interval in accordance with one of the user-selected time interval.

48. The system of claim 42, wherein the substantially concrete structure has a first side from which the transmitted and detected electromagnetic signals are transmitted and detected, respectively, and wherein the amplitude determination module includes:

an adjustment module to receive the determined amplitudes, to adjust each determined amplitude to accommodate for attenuation of the selected signal from which the amplitude was determined due to a distance of the reinforcing bar corresponding to the selected signal from the first side, and output the adjusted amplitudes,

wherein the extent of deterioration of the one or more areas is determined from the adjusted amplitudes.

49. The system of claim 42, wherein, for each determined amplitude, the determined amplitude is inversely related to an extent of deterioration of the area of the concrete structure corresponding to the data signal from which the determined amplitude was determined.

50. The system of claim 42, wherein the substantially concrete structure has a first side, and the data analysis application further includes:

a coordinate determination module to receive the selected data signals, determine, for each determined amplitude, a coordinate of the determined amplitude on a two-dimensional representation of the first side, and output the determined coordinates,

wherein the system further comprises a display device to receive the determined coordinates and display the two-dimensional representation of the first side of the substantially concrete structure, each determined amplitude represented at the determined coordinate with a value corresponding to the determined amplitude,

wherein the extent of deterioration of the one or more areas is determined by visual inspection of the two-dimensional representation.

51. The system of claim 50, wherein each determined amplitude is represented in the two-dimensional representation as a color or grayscale value.

52. The system of claim 41, wherein the data signals include one or more first data signals corresponding to electromagnetic energy having an electric field polarized primarily in the first direction and one or more second data signals corresponding to electromagnetic energy having an electric field polarized primarily in the second direction substantially orthogonal to the first direction, wherein each first data signal has an associated second data signal detected from a same area as the first data signal, and wherein the data analysis application includes:

a subtraction module to receive the first and second data signals, to subtract, for each first data signal, the associated second data signal from the first data signal to produce a third signal,

wherein the extent of deterioration of the one or more areas is determined from the third signal.

53. The system of claim 52, wherein the data analysis application further includes:

an amplitude determination module to receive the third signals, determine an amplitude of each third signal, and output the determined amplitudes,

wherein the extent of deterioration of the one or more areas is determined from the determined amplitudes.

54. The system of claim 53, wherein the substantially concrete structure contains one or more reinforcing bars, and wherein the determined amplitude of each selected third signal is an amplitude resulting from electromagnetic energy reflected from one or more of the one or more reinforcing bars.

55. The system of claim 54, wherein the substantially concrete structure has a first side, each transmitted electromagnetic signal having been transmitted at a different position along the first side of the concrete structure, wherein each data signal represents an electromagnetic signal collected over a period of time, and wherein, for each third signal, data analysis module further includes:

a time interval selection module to receive the one or more data signals, to select, for each data signal, a time interval of the data signal during which the energy reflected from the one or more corresponding reinforcing bars was detected, and to output the selected time intervals; and

a peak amplitude determination module to receive the one or more data signals, to determine, for each data signal, a peak amplitude of the data signal during the selected time interval, and to output the peak amplitudes,

wherein the extent of deterioration of the one or more areas is determined from the peak amplitudes.

56. The system of claim 55, further comprising:

a graphical user interface to receive the one or more data signals and display a representation of the one or more data signals with respect to the first side of the concrete structure, each signal plotted as a function of time, to receive one or more first user-selected inputs, each first input indicative of a time interval, and to send each user-selected time interval to the first selection module,

wherein the first selection module selects each selected time interval in accordance with one of the user-selected time interval.

57. The system of claim 53, wherein the substantially concrete structure has a first side from which the transmitted and detected electromagnetic signals are transmitted and detected, respectively, and wherein the substantially concrete structure contains one or more reinforcing bars, and wherein each determined amplitude corresponds to reflections of electromagnetic energy from one or more of the one or more reinforcing bars, wherein the amplitude determination module includes:

an adjustment module to receive the determined amplitudes, to adjust each determined amplitude to accommodate for attenuation of the selected signal from which the amplitude was determined due to a distance from the first side of the one or more reinforcing bar corresponding to the selected signal, and output the adjusted amplitudes,

wherein the extent of deterioration of the one or more areas is determined from the adjusted amplitudes.

58. The system of claim 53, wherein, for each determined amplitude, the determined amplitude is inversely related to an extent of deterioration of the area of the concrete structure corresponding to the data signals from which the determined amplitude was determined.

59. The system of claim 53, the substantially concrete structure has a first side, and the data analysis application further includes:

a coordinate determination module to receive the third signals, determine, for each determined amplitude, a coordinate of the determined amplitude on a two-dimensional representation of the first side, and output the determined coordinates,

wherein the system further includes a display device to receive the determined coordinates and display the two-dimensional representation of the first side of the substantially concrete structure, each determined amplitude represented at the determined coordinate with a value corresponding to the determined amplitude, and

wherein the extent of deterioration of the one or more areas is determined by visual inspection of the two-dimensional representation.

60. The system of claim 59, wherein each determined amplitude is represented in the two-dimensional representation as a color or grayscale value.

61. The system of claim 41, wherein the data analysis application includes:

a data adjustment module to receive the one or more data signals, adjust each signal by removing from each data signal data representing electromagnetic signals not reflected from the substantially concrete structure, and output the adjusted signals,

wherein the extent of deterioration at one or more areas within the substantially concrete structure is determined from the adjusted data signals.

62. The system of claim 61, wherein at least a first side of the substantially concrete structure is adjacent to one or more layers of material, and each transmitted signal is transmitted through the one or more layers, and wherein the data removed by the data adjustment module includes data representing electromagnetic signals reflected from the one or more layers.

63. The system of claim 41, further comprising:

an antenna unit to transmit one or more of the electromagnetic signals into the concrete structure that result in the reflected electromagnetic energy.

47. The system of 46, wherein the graphical user interface receives one or more second user-selected inputs, each second input indicative of a spatial interval along the first side of the concrete structure, and sends each user-selected spatial interval to the first selection module,

wherein the first selection module determines each spatial interval in accordance with one of the user-selected spatial intervals.

64. A method of determining the condition of at least a portion of a substantially concrete structure, the method comprising:

transmitting one or more electromagnetic signals into the substantially concrete structure;

for each transmitted signal, detecting a corresponding electromagnetic signal from the substantially concrete structure, the detected signal including electromagnetic energy reflected from the substantially concrete structure as a result of the transmitted signal; and

determining from the detected electromagnetic signals an extent of deterioration of one or more areas within the substantially concrete structure.

65. The method of claim 64, wherein a plurality of the electromagnetic signals are transmitted contemporaneously from a plurality of locations.

66. The method of claim 64, wherein electromagnetic signals are transmitted sequentially from a plurality of locations.