Real-time pavement profile sensing system using air-coupled surface wave

Patent metadata

Field	Value
Publication number	US-9921187-B2
Application number	US-201213980013-A
Country	US
Kind code	B2
Filing date	Jan 20, 2012
Priority date	Jan 20, 2011
Publication date	Mar 20, 2018
Grant date	Mar 20, 2018

Abstract

A non-contact testing system and method using acoustic sensors and a mobile sensing system using this system and method is disclosed. The leaky surface wave is recorded with directional microphones. A fast inversion analysis algorithm is introduced to estimate the shear velocity profile and elastic modulus for the subsurface layers of pavement structures, using the dispersion curves obtained from the acoustic signals. An electrical hammer is used to produce impact impulses automatically. A mobile sensing system is integrated on a mobile cart to perform the mobile subsurface sensing for pavement structures.

First claim

What is claimed is:

1. A method for characterizing at least one layer of pavement to a predetermined penetrating depth, comprising:
providing a data processor for receiving audio input signals;
disposing an array of microphones proximate an upper surface of the pavement, the array being disposed on a wheeled platform and in communication with the data processor for communicating audio input signals thereto;
applying a substantially vertical point load impact to the pavement;
detecting with a plurality of microphones in the array a leaky surface wave generated by the impact;
defining, by the data processor, a dispersion curve from the leaky surface wave, the dispersion curve mapping phase velocity versus wavelength or frequency; and
calculating an inversion of the dispersion curve, by the processor, by
starting at the lowest wavelength or highest frequency corresponding to the pavement surface, and repeating for each consecutive higher wavelength or lower frequency corresponding to a substantially horizontal layer along the predetermined penetrating depth, dividing the respective phase velocity value by a predetermined estimate of the amplitude of particle vertical displacement for the substantially horizontal layer, while assuming all deeper layers are uniform half-space, to derive estimates of shear velocity at corresponding penetrating depths, and
iteratively adjusting the estimates of shear velocity by repeating, starting at the lowest wavelength or highest frequency and for each consecutive higher wavelength or lower frequency corresponding to each substantially horizontal layer along the predetermined penetrating depth, the steps of dividing the respective phase velocity value by a predetermined estimate of the amplitude of particle vertical displacement for the substantially horizontal layer, while taking into consideration the derived estimates of shear velocity value, until convergence; whereby the method is repeated at each of consecutive locations on the pavement as traversed by the wheeled platform.

2. The method of claim 1 , wherein the step of defining the dispersion curve is performed within a frequency band across which a coherence curve, calculated by the data processor from the audio signals, has coherence values substantially equal to one.

3. The method of claim 1 , further comprising the step of temporally windowing the received audio signals, by the data processor, to eliminate direct acoustic noise resulting from the impact.

4. The method of claim 1 , further comprising the step of providing a sound barrier enclosure for each microphone of the array of microphones.

5. The method of claim 4 , wherein the sound barrier enclosure comprises a substantially cylindrical enclosure having a first closed end, a second open end, and a cylindrical wall, the respective microphone being disposed within and coaxially with the substantially cylindrical enclosure.

6. The method of claim 5 , wherein the exterior surface of at least one of the first closed end and the cylindrical wall is provided with a sound reflecting material.

7. The method of claim 5 , wherein the interior surface of at least one of the first closed end and the cylindrical wall is provided with a sound absorbing material.

8. The method of claim 1 , wherein the step of disposing an array of microphones comprises disposing an array of directional microphones, each having a respective acoustic axis substantially orthogonal to the pavement upper surface.

9. The method of claim 1 , wherein the predetermined estimate of the amplitude of particle vertical displacement correlates dimensionless particle displacement with dimensionless depth, and is dependent upon a value for Poisson's ratio.

10. The method of claim 9 , wherein a Poisson's ratio value is provided to the data processor by an operator using an operator interface based upon at least one pavement material believed to be present in the pavement to be characterized.

11. A system for characterizing at least one layer of pavement to a predetermined penetrating depth, comprising:
a data processor for receiving audio input signals;
an array of microphones proximate an upper surface of the pavement, the array being in communication with the data processor, for detecting a leaky surface wave in the pavement, and for communicating audio input signals in response to the detected leaky surface wave; a substantially vertical point load impact subsystem for selectively imparting a point load impact onto the pavement surface and for generating the leaky surface wave in the pavement, and
a wheeled platform; wherein the data processor, the array of microphones, and the substantially vertical point load impact subsystem are disposed on the wheeled platform and the system can be transported on the pavement;
wherein the data processor is operative to define a dispersion curve from the leaky surface wave, the dispersion curve mapping phase velocity versus wavelength or frequency; and
wherein the data processor is further operative to calculate an inversion of the dispersion curve by,
starting at the lowest wavelength or highest frequency corresponding to the pavement surface, and repeating for each consecutive higher wavelength or lower frequency corresponding to a substantially horizontal layer along the predetermined penetrating depth, dividing the respective phase velocity value by a predetermined estimate of the amplitude of particle vertical displacement for the substantially horizontal layer, while assuming all deeper layers are uniform half-space, to derive estimates of shear velocity at corresponding penetrating depths, wherein the predetermined estimate of the amplitude of particle vertical displacement correlates dimensionless particle displacement with dimensionless depth, and

iteratively adjusting the estimates of shear velocity by repeating, starting at the lowest wavelength or highest frequency and for each consecutive higher wavelength or lower frequency corresponding to each substantially horizontal layer along the predetermined penetrating depth, the steps of dividing the respective phase velocity value by a predetermined estimate of the amplitude of particle vertical displacement for the substantially horizontal layer, while taking into consideration the derived estimates of shear velocity value, until convergence.

12. The system of claim 11 , wherein the data processor further comprises a data acquisition unit for sampling the audio input signals and for generating a digital representation thereof.

13. The system of claim 11 , further comprising a global positioning system receiver for providing location information to the data processor.

14. The system of claim 11 , further comprising a trigger for enabling selective triggering of the point load impact subsystem.

15. The system of claim 11 , wherein the data processor is further operative to calculate an inversion of the dispersion curve by correlating dimensionless particle displacement with dimensionless depth as the predetermined estimate of the amplitude of particle vertical displacement.

16. The system of claim 11 , wherein the data processor is further operative to temporally window the received audio signals to eliminate direct acoustic noise resulting from the impact.

17. The system of claim 11 , further comprising a sound barrier enclosure for each microphone of the array of microphones.

18. The system of claim 17 , wherein the sound barrier enclosure comprises a substantially cylindrical enclosure having a first closed end, a second open end, and a cylindrical wall,

Assignees

• Cao Yinghong
• Wang Ming
• Univ Northeastern

Inventors

• Cao Yinghong
• Wang Ming

Classifications

• E01C23/01

  Devices or auxiliary means for setting-out or checking the configuration of new surfacing, e.g. templates, screed {or reference line} supports (form rails E01C19/50); Applications of apparatus for measuring, indicating, or recording the surface configuration of existing surfacing, e.g. profilographs (E01C23/07 takes precedence; measuring roughness or irregularity in general G01B) · CPC title

• G01N2291/044

  Internal reflections (echoes), e.g. on walls or defects · CPC title

• G01N29/11 Primary

  by measuring attenuation of acoustic waves · CPC title

• G01V1/303 Primary

  for determining velocity profiles or travel times · CPC title