ULTRASONIC SHEAR‐WAVE VELOCITIES IN ROCKS SUBJECTED TO SIMULATED OVERBURDEN PRESSURE

Geophysics ◽  
1962 ◽  
Vol 27 (5) ◽  
pp. 590-598 ◽  
Author(s):  
M. S. King ◽  
I. Fatt
Keyword(s):  
Shear Wave ◽  
High Pressures ◽  
Applied Pressure ◽  
Ultrasonic Energy ◽  
Overburden Pressure ◽  
Wave Velocities ◽  
Shear Wave Velocities ◽  
Ultrasonic Equipment ◽  
The One ◽  
Ultrasonic Shear

Ultrasonic equipment has been developed to measure shear‐wave velocities in small rock samples at hydrostatic pressures up to 2,400 psi. Under certain optimum conditions dilatational wave velocities can also be determined. The method employs a beam of ultrasonic energy passing through a liquid in which a quarter‐inch‐thick parallel‐sided sample of rock is rotated. From the laws of classical optics for the refraction and reflection of waves at boundaries between dissimilar media and the known velocity of sound in the liquid, the velocities in the sample may be calculated from a record of ultrasonic energy transmitted through the sample as a function of angle between the sample and the ultrasonic beam. Results obtained with this apparatus from samples of materials for which the velocity of waves has been published show good agreement with the latter. The variation of the velocity of shear waves in dry rocks with applied hydrostatic pressures up to 2,400 psi have been measured for seven sandstones, a chalk, and a limestone. The shear‐wave velocities were found to increase with an increase of the applied pressure. For five of the sandstones the increase in velocity at high pressures approached the one‐sixth power of the applied hydrostatic pressure predicted theoretically for a sphere pack model.

Measurement of dynamic properties of stiff specimens using ultrasonic waves

2011 ◽  
Vol 48 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Zahid Khan ◽  
Giovanni Cascante ◽  
M. Hesham El Naggar
Keyword(s):  
Shear Wave ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Ultrasonic Waves ◽  
Resonant Column ◽  
Reliable Determination ◽  
Cemented Sand ◽  
Wave Velocities ◽  
Shear Wave Velocities ◽  
Ultrasonic Equipment

The measurement of low-strain properties (wave velocity and damping ratio) of geomaterials is affected by equipment-generated delays, coupling of transducers, and wave reflections. This study presents a new technique to measure ultrasonic properties of stiff specimens accurately. Compressional-wave velocities in cylindrical rods of different lengths and materials were measured using different ultrasonic equipment. The error induced by different equipment was below 1% after the measurements were corrected by the equipment time delay. Shear-wave velocities of different materials were measured using ultrasonic transducers (frequency < 1 MHz) and a resonant column device (frequency < 200 Hz). The difference in shear-wave velocities was less than 4%, and the measured values are in agreement with published results for all tested materials. A new methodology based on the first two reflections of the main pulse has been developed to measure the damping ratio of stiff specimens using ultrasonic equipment. The ultrasonic measurements of the damping ratio compare well with resonant column results. A more reliable determination of the dynamic Poisson’s ratio of a cemented sand was achieved using corrected ultrasonic-wave velocities.

ULTRASONIC SHEAR‐WAVE VELOCITIES IN ROCKS SUBJECTED TO SIMULATED OVERBURDEN PRESSURE AND INTERNAL PORE PRESSURE

Geophysics ◽  
1965 ◽  
Vol 30 (1) ◽  
pp. 117-121 ◽  
Author(s):  
B. S. Banthia ◽  
M. S. King ◽  
I. Fatt
Keyword(s):  
Hydrostatic Pressure ◽  
Pore Pressure ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Overburden Pressure ◽  
Wave Velocities ◽  
Shear Wave Velocities ◽  
The Matrix ◽  
Internal Pore

Change in shear‐wave velocity for four dry sedimentary rocks has been studied as a function of the variation of both external hydrostatic pressure and internal pore pressure in the range 0 to 2,500 psi. The experimental method employs a beam of ultrasonic energy passing through a liquid in which a copper‐jacketed parallel‐sided slab of rock is rotated. The shear‐wave velocity is calculated from the laws of refraction and reflection of waves at a liquid‐solid boundary applied to the angle at which minimum energy is transmitted. The variation of shear‐wave velocity with pressure has been found to be a function of net overburden pressure, [Formula: see text], where [Formula: see text] hydrostatic pressure on the jacketed sample, [Formula: see text] pore pressure and n = a pressure‐dependent factor less than unity. The values of n at several differential pressures were chosen to yield a smooth curve passing through the displaced data points when the shear‐wave velocities were plotted as a function of net overburden pressure. Using the n values so obtained, the matrix compressibility [Formula: see text] for two of the sandstones has been calculated from the relation [Formula: see text]. The bulk compressibility [Formula: see text] for these two rocks had previously been obtained experimentally as a function of differential pressure. The values obtained for the matrix compressibility are in the range expected from a knowledge of the grain and cementing materials for these sandstones.

Soil moisture assessment by means of compressional and shear wave velocities: Theoretical analysis and experimental setup

Measurement ◽  
2010 ◽  
Vol 43 (3) ◽  
pp. 344-352 ◽  
Author(s):  
F. Adamo ◽  
F. Attivissimo ◽  
L. Fabbiano ◽  
N. Giaquinto ◽  
M. Spadavecchia
Keyword(s):  
Soil Moisture ◽  
Theoretical Analysis ◽  
Shear Wave ◽  
Experimental Setup ◽  
Wave Velocities ◽  
Shear Wave Velocities
Sign in / Sign up

Export Citation Format

Share Document