scholarly journals Correlating Natural, Dry, and Saturated Ultrasonic Pulse Velocities with the Mechanical Properties of Rock for Various Sample Diameters

2020 ◽  
Vol 10 (24) ◽  
pp. 9134
Author(s):  
Hasan Arman ◽  
Safwan Paramban
Keyword(s):  
Mechanical Properties ◽  
Ultrasonic Pulse ◽  
Point Load ◽  
P Wave ◽  
Point Load Index ◽  
Sample Diameter ◽  
Wave Velocities ◽  
P Wave Velocity ◽  
Indirect Tensile ◽  
P Wave Velocities

P-wave velocity is employed in various fields of engineering to estimate the mechanical properties of rock, as its measurement is reliable, convenient, rapid, nondestructive, and economical. The present study aimed to (i) correlate natural, dry, and saturated P-wave velocities with the mechanical properties of limestone and (ii) investigate how the ultrasonic P-wave velocities and mechanical properties of limestone are affected by the sample diameter. This study reveals that P-wave velocities under different environmental conditions can be correlated with the mechanical properties of limestone. Further, the R-value variations with different P-wave velocities for a given sample diameter are (i) negligible in terms of the uniaxial compressive strength (UCS) excluding 63.2 mm, (ii) limited for the diametrical point load index (PLID) except for 53.9 mm, (iii) perceived in case of the axial point load index (PLIA) for 47.7 mm, (iv) observed for the indirect tensile strength (ITS), but generally insignificant, and (v) detected in terms of Schmidt hammer value (SHV) except for 47.7 mm.

Internal Structure of Venere Mud Volcano in the Crotone Forearc Basin, Calabrian Arc, Italy, from Multibeam Bathymetry, Wide-Angle and Multichannel Seismic Data

2020 ◽  
Author(s):  
Michael Riedel ◽  
Anne Krabbenhoeft ◽  
Cord Papenberg ◽  
Joerg Bialas ◽  
Gerhard Bohrmann ◽  
...  
Keyword(s):  
Internal Structure ◽  
Seismic Data ◽  
P Wave ◽  
Wide Angle ◽  
Multibeam Bathymetry ◽  
Mud Volcanoes ◽  
Acoustic Basement ◽  
Wave Velocities ◽  
P Wave Velocity ◽  
P Wave Velocities

<p>Mud volcanoes (MVs) have been found in various geological settings on passive and active margins but are mostly known from collision zones on Earth. Mud volcanoes are well known to occur on land (e.g. in Azerbaijan), where at least 1000 MVs have been counted. The amount of submarine MVs is believed to be much larger and recent improvements in seafloor mapping led to the discovery of many MVs in all oceans. To contribute to the knowledge of submarine MVs, in particular the internal structure across Venere MV, we conducted a multi-geophysical imaging approach using high resolution multibeam bathymetry, (constraining seafloor expressions), multichannel, and wide-angle seismic data (constraining the internal structure and P-wave velocity distribution). Venere MV is located at the southern rim of the Crotone forearc basin of the Calabrian arc, offshore southern Italy, in a water depth of ~1500 m. The dimension of Venere MV from its bathymetric expression is ~10 km in the EW- and ~7 km in the NS-direction. Two circular cones of ~100 m elevation and ~1.5 km diameter are located in the center of Venere MV. The upper 200 m below the seafloor (bsf) consist of layers with seismic P-wave velocities gradually increasing from 1.53 to 1.7 km/s (sub-) parallel to the seafloor. A prominent reflection ~200 m bsf and a sudden increase of seismic P-wave velocities from 1.7 to 1.8 km/s mark a change with depth in the internal structure, where reflections dip, and seismic P-wave velocities laterally decrease towards the center of Venere MV. The MCS as well as seismic P-wave velocity structure indicate two separate feeder conduits of the two center cones of Venere MV. However, we do not map the roots of the MV, which are at depths beyond our data resolution. Reduced reflectivity occurs ~4 km across the center of the MV 200 m bsf and downwards. We mapped the chaotic reflections of the acoustic basement in depths varying from 500 m to 800 m bsf. Reduced reflectivity of the acoustic basement occurs beneath the center of the MV as well. Mapping of the fault system leads to the subseafloor dimension of Venere MV that exceeds its seafloor dimension by the factor of two.</p>

Localizing CO2 at Sleipner — Seismic images versus P-wave velocities from waveform inversion

Geophysics ◽  
2013 ◽  
Vol 78 (3) ◽  
pp. B131-B146 ◽  
Author(s):  
Manuel Queißer ◽  
Satish C. Singh
Keyword(s):  
Wave Velocity ◽  
Waveform Inversion ◽  
P Wave ◽  
Full Waveform Inversion ◽  
Wave Velocities ◽  
Full Waveform ◽  
P Wave Velocity ◽  
Seismic Image ◽  
P Wave Velocities ◽  
Seismic Images

The presence of injected [Formula: see text] in the Utsira Sand at the Sleipner site, Norway, is associated with a high negative P-wave velocity anomaly; that is, a low postinjection velocity and a strong seismic response. Time-lapse seismic imaging of [Formula: see text] injection at Sleipner is thus a viable monitoring tool of the injected [Formula: see text]. The work flow usually involves conventional seismic processing, including stacking, and results in seismic images. Multiple reflections, interference effects such as tuning, and the velocity pushdown effect due to [Formula: see text] injection render these seismic images ambiguous in terms of the localization and the quantification of the [Formula: see text] in the Utsira Sand. Nonetheless, seismic images often form the basis for analyses that aim to quantify the injected [Formula: see text]. We employed elastic 2D full waveform inversion to invert prestack seismic Sleipner data from preinjection (1994) and postinjection (1999) and compared the resulting postinjection P-wave velocity model with the corresponding seismic image. We found that the high-amplitude reflections in the seismic image do not everywhere coincide with low postinjection P-wave velocities. Drawing extensive and integrated conclusions is out of our scope, because this would require full control over the seismic data processing and a more comprehensive forward modeling. For instance, modeling should be done in 3D and an adequate anelasticity formulation should be added. However, the waveform inversion scheme we used accounts for all the aforementioned elastic propagation effects. The results therefore suggested that the exclusive use of seismic images to quantify [Formula: see text] could be revised and full waveform inversion should be added to the analysis toolbox.

scholarly journals In‐situ, high‐frequency P-wave velocity measurements within 1 m of the earth’s surface

Geophysics ◽  
1999 ◽  
Vol 64 (2) ◽  
pp. 323-325 ◽  
Author(s):  
Gregory S. Baker ◽  
Don W. Steeples ◽  
Chris Schmeissner
Keyword(s):  
Wave Velocity ◽  
Speed Of Sound ◽  
P Wave ◽  
Sound Waves ◽  
Low Velocity ◽  
Near Surface ◽  
Wave Velocities ◽  
P Wave Velocity ◽  
P Wave Velocities

Seismic P-wave velocities in near‐surface materials can be much slower than the speed of sound waves in air (normally 335 m/s or 1100 ft/s). Difficulties often arise when measuring these low‐velocity P-waves because of interference by the air wave and the air‐coupled waves near the seismic source, at least when gathering data with the more commonly used shallow P-wave sources. Additional problems in separating the direct and refracted arrivals within ∼2 m of the source arise from source‐generated nonlinear displacement, even when small energy sources such as sledgehammers, small‐caliber rifles, and seismic blasting caps are used. Using an automotive spark plug as an energy source allowed us to measure seismic P-wave velocities accurately, in situ, from a few decimeters to a few meters from the shotpoint. We were able to observe three distinct P-wave velocities at our test site: ∼130m/s, 180m/s, and 300m/s. Even the third layer, which would normally constitute the first detected layer in a shallow‐seismic‐refraction survey, had a P-wave velocity lower than the speed of sound in air.

Using P-wave velocity logs with petrofabric effects to map natural and blast-induced fractures in hard rocks

2001 ◽  
Vol 7 (3) ◽  
pp. 267-279 ◽  
Author(s):  
Kitchakarn Promma
Keyword(s):  
Wave Velocity ◽  
P Wave ◽  
Hard Rocks ◽  
Wave Velocities ◽  
Rock Types ◽  
Full Waveform ◽  
P Wave Velocity ◽  
P Wave Velocities ◽  
Induced Fractures ◽  
Sonic Logs

Abstract A challenging task in environmental geophysics is to locate fractures near a leaching stope in an underground mine. Existing methods for interpreting sonic logs do not incorporate petrofabric effects. The petrofabric effects are variations of P-wave velocities caused by textural variations in the lithology. This paper describes a new concept of using the petrofabric effects in the logs to determine anomalies of natural and blast-induced fractures in hard rocks. Full-waveform acoustic logs were acquired near an underground stope at the Colorado School of Mines Experimental Mine, Idaho Springs, Colorado. Data acquisition occurred once before the stope was blasted and twice after the blast event. Laboratory studies show that the petrofabric effects range from 4 to 15 percent. This variation depends on rock types. To interpret location of fractures, variation envelopes of petrofabric effects were placed in P-wave velocity logs. P-wave velocities that are lower than lower limits of the variation envelopes indicate natural and blast-induced fractures. Results show that the blasting broke the entire rock mass within 6 ft from the stope's perimeter. The use of petrofabric effect interpretation improves effectiveness of P-wave velocity logs in identifying fractures.

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