Experimental Study of Time-Frequency Effect of Rocks

2012 ◽  
Vol 204-208 ◽  
pp. 755-760
Author(s):  
Xin Lin Wan ◽  
Su Zhang
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Sine Wave ◽  
Intersection Point ◽  
Frequency Effect ◽  
Nonlinear Frequency ◽  
Time Frequency ◽  
Physical Mechanisms ◽  
Nonlinear Frequency Response ◽  
Water Saturated

Sine wave loading experiments are carried out on MTS for pump-oil saturated Nanjing sandstones and water saturated Dali marbles. The Young’s modulus and velocities of longitudinal wave and transverse wave increase with the frequency, and there are notable dispersions. The existence of micro defects in saturated rocks result in hysteresis at the sinusoidal loading experiments. The variation curves of instantaneous Young’s modulus with stress for loading and unloading intersect, and an “X” shape figure is obtained. As the frequency of the sinusoidal wave increases, the position of the intersection point moves to higher modulus area. Thus the modulus dispersion increases. Some physical mechanisms of nonlinear frequency response of rock are revealed. The results obtained are very important for nonlinear wave study, and the theoretical study and application of earthquake and engineering.

Frequency-dependent attenuation in water-saturated cracked glass based on creep tests

Geophysics ◽  
2017 ◽  
Vol 82 (3) ◽  
pp. MR89-MR96 ◽  
Author(s):  
Céline Mallet ◽  
Beatriz Quintal ◽  
Eva Caspari ◽  
Klaus Holliger
Keyword(s):  
Young’S Modulus ◽  
Glass Sample ◽  
Young's Modulus ◽  
Axial Stress ◽  
Creep Tests ◽  
Crack Network ◽  
Frequency Dependent ◽  
Essential Information ◽  
Poroelastic Model ◽  
Water Saturated

We estimate attenuation at subseismic frequencies from an experimental creep test performed on a thermally cracked water-saturated glass sample. The time-dependent axial stress and strain rates are used to infer the attenuation and Young’s modulus as functions of frequency. Attenuation is characterized by a pronounced frequency dependence between [Formula: see text] and [Formula: see text]. A corresponding frequency-dependent behavior of the Young’s modulus is observed with an increase from 60 to 70 GPa, which is consistent with the measured static and ultrasonic values. These observations are interpreted as being due to fluid flow between interconnected cracks in the mesoscopic scale range. To test this hypothesis, we compare the analytical characteristic frequency for the presumed mesoscopic squirt-type flow with its experimental counterpart. We also compare the experimentally observed attenuation characteristics with results of numerical simulations. For the latter, a thin section of the cracked glass sample has been digitized to provide essential information with regard to the geometry of the crack network. Together with the known physical properties of the intact glass matrix, this then allows for deriving a first-order 2D poroelastic model for the cracked sample based on Biot’s quasi-static equations.

scholarly journals Experimental Study on Anisotropic Strength and Deformation Behavior of a Coal Measure Shale under Room Dried and Water Saturated Conditions

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Jingyi Cheng ◽  
Zhijun Wan ◽  
Yidong Zhang ◽  
Wenfeng Li ◽  
Syd S. Peng ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Water Content ◽  
Young’S Modulus ◽  
Deformation Behavior ◽  
Young's Modulus ◽  
Triaxial Compression ◽  
Coal Measure ◽  
Anisotropic Strength ◽  
Strength And Deformation ◽  
Water Saturated

This paper presents an experimental investigation of anisotropic strength and deformation behavior of coal measure shale. The effect of two factors (i.e., anisotropy and water content) on shale strength and deformation behavior was studied. A series of uniaxial and triaxial compression tests were conducted on both room dried and water saturated samples for different lamination angles. The test results indicate that (1) the compressive strength, cohesion, internal friction angle, tangent Young’s modulus, and axial strain corresponding to the peak and residual strengths of room dried specimens exhibit anisotropic behavior that strongly depends on the orientation angle(β); (2) in comparison to the room dried samples, the compressive strength and Young’s modulus as well as the anisotropy are all reduced for water saturated specimens; and (3) the failure mechanism of the samples can be summarized into two categories: sliding along lamination and shearing of rock material, with the type occurring in a particular situation depending strongly on the lamination orientation angles with respect to the major principal stress. According to the findings, it is strongly recommended that the effect of anisotropy and water content on the strength and deformation behavior of the rock must be considered in ground control designs.

EFFECT OF PORE FLUIDS ON THE ELASTIC PROPERTIES OF SANDSTONE

Geophysics ◽  
1960 ◽  
Vol 25 (2) ◽  
pp. 433-444 ◽  
Author(s):  
R. L. Mann ◽  
I. Fatt
Keyword(s):  
Young’S Modulus ◽  
Elastic Properties ◽  
Poisson’S Ratio ◽  
Elastic Moduli ◽  
Young's Modulus ◽  
Clay Content ◽  
Poisson's Ratio ◽  
Statistical Validity ◽  
Bulk Compressibility ◽  
Water Saturated

Bulk compressibility, Young’s modulus, and Poisson’s ratio were measured on three sandstones. Measurements were made on both dry and water saturated samples. Several runs were made on each sandstone to establish the statistical validity of the differences observed between the wet and dry samples. Bulk compressibility of wet sandstone was 10 to 30 percent greater than for dry. Young’s modulus was 8 to 20 percent less for wet sandstone, and Poisson’s ratio was 100 percent greater on one type of sandstone when wet and only slightly greater or about the same on wet samples of the others. A high clay content is believed to lead to a large effect of water on the elastic moduli of sandstone.

scholarly journals Discrepancy between measured dynamic poroelastic parameters and predicted values from Wyllie’s equation for water-saturated Istebna sandstone

2021 ◽  
Author(s):  
Dariusz Knez ◽  
Herimitsinjo Rajaoalison
Keyword(s):  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Young's Modulus ◽  
Laboratory Data ◽  
Confining Pressure ◽  
P Wave ◽  
Poisson's Ratio ◽  
Rock Properties ◽  
Biot’S Coefficient ◽  
Water Saturated

AbstractThe drilling-related geomechanics requires a better understanding of the encountered formation properties such as poroelastic parameters. This paper shows set of laboratory results of the dynamic Young’s modulus, Poisson’s ratio, and Biot’s coefficient for dry and water-saturated Istebna sandstone samples under a series of confining pressure conditions at two different temperatures. The predicted results from Wyllie’s equation were compared to the measured ones in order to show the effect of saturation on the rock weakening. A negative correlation has been identified between Poisson’s ratio, Biot’s coefficient and confining pressure, while a positive correlation between confining pressure and Young’s modulus. The predicted dynamic poroelastic rock properties using the P-wave value from Wyllie’s equation are different from measured ones. It shows the important influence of water saturation on rock strength, which is confirmed by unconfined compressive strength measurement. Linear equations have been fitted for the laboratory data and are useful for the analysis of coupled stress and pore pressure effects in geomechanical problems. Such results are useful for many drilling applications especially in evaluation of such cases as wellbore instability and many other drilling problems.

Static and dynamic Young’s moduli of chalk from the North Sea

Geophysics ◽  
2008 ◽  
Vol 73 (2) ◽  
pp. E41-E50 ◽  
Author(s):  
Casper Olsen ◽  
Helle Foged Christensen ◽  
Ida L. Fabricius
Keyword(s):  
Young’S Modulus ◽  
North Sea ◽  
Strain Gauge ◽  
Young's Modulus ◽  
Displacement Transducer ◽  
Dynamic Young’S Modulus ◽  
Young’S Moduli ◽  
Static Young’S Modulus ◽  
Dynamic Young's Modulus ◽  
Water Saturated

We present results from a study of dynamic and static Young’s moduli of North Sea chalk based on laboratory tests on both dry and water-saturated chalk. We obtained static moduli by using both strain gauge and linear voltage displacement transducer (LVDT) measurements. We investigated the influence of pore fluid on static and dynamic Young’s moduli and evaluated the two methods for obtaining static Young’s modulus. We obtained good agreement between dynamic and static Young’s moduli from strain gauge measurements on dry chalk, but for water-saturated chalk the dynamic Young’s modulus was larger than the measured static Young’s modulus. This difference may be caused in part by the influence of the difference in frequencies of static and dynamic measurements. Another reason for the observed difference may be a practical experimental problem that causes the measured static Young’s modulus for water-saturated chalk to be lower than the true modulus. When we compared dynamic Young’s modulus for dry chalk with that for water-saturated chalk, the dry modulus was larger than the water-saturated modulus, probably owing to shear weakening of the chalk. Young’s modulus from LVDT measurements does not relate to dynamic Young’s modulus for dry or water-saturated rock because the LVDT is not able to accurately measure the small deformations of the samples during loading at relatively low stresses.

Mechanical properties of FeAlSi powders prepared by mechanical alloying from different initial feedstock materials

2019 ◽  
Vol 107 (2) ◽  
pp. 207 ◽  
Author(s):  
Jaroslav Čech ◽  
Petr Haušild ◽  
Miroslav Karlík ◽  
Veronika Kadlecová ◽  
Jiří Čapek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Alloying ◽  
Young’S Modulus ◽  
Milling Time ◽  
Young's Modulus ◽  
Element Model ◽  
X Ray Diffraction ◽  
X Ray ◽  
Powder Particles ◽  
Complete Homogenization

FeAl20Si20 (wt.%) powders prepared by mechanical alloying from different initial feedstock materials (Fe, Al, Si, FeAl27) were investigated in this study. Scanning electron microscopy, X-ray diffraction and nanoindentation techniques were used to analyze microstructure, phase composition and mechanical properties (hardness and Young’s modulus). Finite element model was developed to account for the decrease in measured values of mechanical properties of powder particles with increasing penetration depth caused by surrounding soft resin used for embedding powder particles. Progressive homogenization of the powders’ microstructure and an increase of hardness and Young’s modulus with milling time were observed and the time for complete homogenization was estimated.

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