[Investigation of ultrasonic wave interaction with porous saturated rocks]
During the last year we have continued our investigation of ultrasonic wave propagation in fluid-filled porous materials. Previously, we studied the feasibility of using different surface modes to characterize both synthetic and natural rocks. We introduced a novel experimental technique based on the direct generation of surface waves by edge excitation. At first, we used two low-frequency (100--500 kHz) shear transducers in pitch-catch mode to launch and receive the ultrasonic surface wave. The contact transducers were coupled to the opposite edges of the porous specimens with normal polarization relative to the surface. The same technique was successfully used to generate Rayleigh-type surface modes on the free surface of both dry and water-saturated specimens, as well as Stoneley-type interface modes on the fluid-loaded surfaces of immersed samples. Recently, we developed a special interferometric technique for non-contact detection of ultrasonic vibrations on diffusely reflecting rough surfaces. This method was found to be more suitable for surface wave inspection of porous ceramics and natural rocks than the previously used contact techniques. Beside investigating guided acoustic waves in water-saturated porous materials, we also studied bulk wave propagation in air-saturated specimens. We further developed our experimental technique which is based on the transmission of airborne ultrasonic waves through air-filled porous plates. This method can be readily used to study the frequency-dependent propagation properties of slow compressional waves in different porous materials including natural rocks. By simple technical improvements, we extended the measuring range so that we could continuously cover both low-frequency (diffuse) and high-frequency (propagating) regimes of slow wave propagation.
- Research Organization:
- Ohio State Univ. Research Foundation, Columbus, OH (United States). Dept. of Welding Engineering
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-87ER13749
- OSTI ID:
- 6523162
- Report Number(s):
- DOE/ER/13749-4; ON: DE93016261
- Country of Publication:
- United States
- Language:
- English
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(Investigation of ultrasonic wave interactions with fluid-saturated porous rocks)
[Investigation of ultrasonic wave interactions with fluid-saturated porous rocks]. [Annual report]