Dynamic response of loess slope with uniform and isotropic layers to vertically incident strong shear waves with different vibrating directions

2013 ◽  
pp. 839-844
Author(s):  
J Sun ◽  
S Dong ◽  
G Li ◽  
M Hao ◽  
F Xiong
Keyword(s):  
Dynamic Response ◽  
Shear Waves ◽  
Loess Slope ◽  
Strong Shear

SHEAR WAVES FROM EXPLOSIVE SOURCES

Geophysics ◽  
1963 ◽  
Vol 28 (6) ◽  
pp. 1001-1019 ◽  
Author(s):  
J. E. White ◽  
R. L. Sengbush
Keyword(s):  
Shear Waves ◽  
Shear Velocity ◽  
Compressional Waves ◽  
Pierre Shale ◽  
Strong Shear ◽  
Water Pulse ◽  
Pulse Waves ◽  
Tube Wave ◽  
A Charge ◽  
Shear Energy

This experimental study of the generation of shear waves by explosive sources stemmed from Heelan’s theoretical result that pressure acting on the wall of a cylindrical hole in a solid should radiate shear waves quite as effectively as compressional waves. The measurements confirm this expectation, but good overall agreement was not achieved until expressions were derived which take into account radiation from strong water‐pulse waves in the shothole. Our results show that the ratio of shear‐to‐compressional amplitudes generated by an explosive source increases as the charge size decreases. At an angle of 45 degrees, the ratio is approximately unity for a charge consisting of 10 ft of Primacord. We found that the shot‐generated water pulse (tube wave) is a strong shear source, continuously generating shear energy in the formation as it travels in the borehole. This drastically affects the directivity of SV waves and in Pierre shale gives a pattern whose maximum is near‐vertical. This suggests the possibility of prospecting with shear waves, using a distributed charge detonated at shear velocity to generate substantial downward‐direction shear energy in the earth. However, the substantially larger attenuation of shear waves compared to compressional waves has discouraged us from pursuing this further.

scholarly journals Wave polarization and dynamic degeneracy in a chiral elastic lattice

2019 ◽  
Vol 475 (2232) ◽  
pp. 20190313 ◽  
Author(s):  
G. Carta ◽  
I. S. Jones ◽  
N. V. Movchan ◽  
A. B. Movchan
Keyword(s):  
Dynamic Response ◽  
Shear Waves ◽  
Low Frequency ◽  
Elementary Cell ◽  
Periodic Lattice ◽  
Wave Polarization ◽  
Lattice Systems ◽  
Systematic Analysis ◽  
Practical Applications ◽  
Elastic Lattice

This paper addresses fundamental questions arising in the theory of Bloch–Floquet waves in chiral elastic lattice systems. This area has received a significant attention in the context of ‘topologically protected’ waveforms. Although practical applications of chiral elastic lattices are widely appreciated, especially in problems of controlling low-frequency vibrations, wave polarization and filtering, the fundamental questions of the relationship of these lattices to classical waveforms associated with longitudinal and shear waves retain a substantial scope for further development. The notion of chirality is introduced into the systematic analysis of dispersive elastic waves in a doubly-periodic lattice. Important quantitative characteristics of the dynamic response of the lattice, such as lattice flux and lattice circulation, are used in the analysis along with the novel concept of ‘vortex waveforms’ that characterize the dynamic response of the chiral system. We note that the continuum concepts of pressure and shear waves do not apply for waves in a lattice, especially in the case when the wavelength is comparable with the size of the elementary cell of the periodic structure. Special critical regimes are highlighted when vortex waveforms become dominant. Analytical findings are accompanied by illustrative numerical simulations.

A swept-frequency borehole source for inverse VSP and cross-borehole surveying

1989 ◽  
Vol 20 (2) ◽  
pp. 133 ◽  
Author(s):  
W. Kennedy ◽  
W. Wiggins ◽  
P. Aronstam ◽  
B.A. Hardage
Keyword(s):  
Resonant Frequency ◽  
Total Energy ◽  
Radiation Pattern ◽  
Shear Waves ◽  
Seismic Source ◽  
P Wave ◽  
Frequency Range ◽  
Pressure Oscillations ◽  
Strong Shear ◽  
Borehole Seismic

A swept-frequency borehole seismic source has been constructed and tested that consists of a portion of the borehole isolated from the remainder and driven to build up pressure oscillations by resonance.The length of the isolated portion is changed to vary the resonant frequency. The source radiates an approximately isotropic P-wave whose total energy is comparable in magnitude to that created by a surface vibrator truck. Strong shear waves are also generated.The source has been tested over a frequency range of 30 to 120 Hz, but the design can be operated from 15 to 500 Hz. Because the driven section of the borehole is isolated, strong tube waves are not generated. No damage to the casing-cement bond has been observed after prolonged operation of the source at a fixed depth.This source has the strength and uniform radiation pattern to suit it for both inverse VSP and cross-borehole surveying.

scholarly journals Dynamic Response Law of Loess Slope with Different Shapes

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Zhixin Yan ◽  
Sen Zhang ◽  
Xuedong Zhang ◽  
Ping Jiang
Keyword(s):  
Dynamic Response ◽  
Construction Projects ◽  
Reference Value ◽  
Northwest China ◽  
Scientific Basis ◽  
Slope Ratio ◽  
Loess Slope ◽  
Theoretical Support ◽  
Ratio Change ◽  
Different Shapes

Loess slope broadly distributes in Northwest China, making the slope of the area developed. And with the development number of construction projects still on the rise, this area is a high-intensity region with multiple earthquakes, resulting in landslide under earthquakes which is a very serious problem. However, the study on the loess slope dynamic response yet rarely involved the exploration of the influence of slope shapes, which leaves a hidden danger to the safety of local engineering. In this paper, a typical ladder-type loess slope in engineering is selected as a research object, and a numerical simulation model is established with FLAC3D program. The dynamic response of the loess slope with different shapes is studied deeply and systematically. Found a series phenomenon of earthquake response of loess slope with stepped slope series, the width of the platform and the slope ratio change under earthquakes. Meanwhile, the law of slope parameters such as slope series, platform width, and slope ratio on dynamic response of loess slope is revealed. The results provide theoretical support and scientific basis for the construction of the relevant projects in the area, which has important reference value to the safety of the engineering and the development of economic society.

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