Quantification Of Rock Damage From Small Explosions And Its Effect On Shear Wave Generation
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Quantification Of Rock Damage From Small Explosions And Its Effect On Shear Wave Generation
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Author :
language : en
Publisher:
Release Date : 2009
Quantification Of Rock Damage From Small Explosions And Its Effect On Shear Wave Generation written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
Weston Geophysical Corp., New England Research, Inc., and several geotechnical consultants conducted the Vermont/New England Damage Experiment in central Vermont during July 2008. A series of five explosions using charges with yields of 135 and 270 lbs and three types of explosives were detonated in homogeneous, low fracture density granite. The goal of the experiment was to generate different amounts of rock damage around the source by using explosives with dramatically different velocities of detonation (VOD), and then relate the shear wave generation to the amount of damage. We used pre- and post-shot core analysis to quantify significant differences in the damage induced by the explosions. Velocities are slower, permeabilities are higher, resistivities are lower, and porosities are higher in the damaged intervals. These results are consistent with a microcrack scale fracture population that is enhanced by the blasts. Over 140 seismic sensors were installed to record the blasts. Peak particle velocity (PPV) studies found that the fastest VOD explosive, Composition B, expended much of its energy at the source pulverizing the surrounding rock, while the middle VOD explosive, heavy ANFO, produced the largest PPV. Source scaling studies found the black powder shot produced seismic amplitudes up to an order of magnitude less than the ANFO and COMP B amplitudes above 5 Hz, but created Rayleigh waves similar in amplitude to those from the ANFO shot. The black powder shot produced larger Rayleigh and Love waves than the COMP B shot. The ANFO and COMP B shots generated similar amplitudes above 8 Hz, but the ANFO source Rayleigh waves were up to twice as large and the Love waves were up to three times as large as those from the COMP B shot. These results indicate that rock damage may be responsible for some of the differences in surface and shear wave generation.
Directiven F R Die Uebungen Der Fuss Artillerie In Festungskriege
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Author :
language : en
Publisher:
Release Date : 1873
Directiven F R Die Uebungen Der Fuss Artillerie In Festungskriege written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1873 with categories.
Generation Of High Frequency P And S Wave Energy By Rock Fracture During A Buried Explosion Its Effect On P S Discriminants At Low Magnitudes
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Author :
language : en
Publisher:
Release Date : 2004
Generation Of High Frequency P And S Wave Energy By Rock Fracture During A Buried Explosion Its Effect On P S Discriminants At Low Magnitudes written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.
High stresses in the source volume of an underground explosion produce a shell of crushed and fractured rock surrounding the shot point. We have modeled this process using a micro-mechanical damage mechanics in an effective medium source model to calculate the nucleation, growth, and interaction of fractures from an array of preexisting flaws. We have found that the nucleation and growth of fracture damage generates secondary seismic radiation that can be comparable in amplitude to the radiation generated by the pressure pulse itself. This secondary radiation is higher frequency than the primary radiation and can have a large shear wave component if there is a preferential orientation of the initial flaws or if there is a significant regional pre-stress field. It can be significant in the interpretation of regional discriminants that use local S phases. We have explored the scaling properties of this secondary radiation by modeling the chemical NPE explosion and US nuclear explosions in granite: HARDHAT, SHOAL, and PILEDRIVER. Finally, we have initiated work to understand the effect of frozen rock at the source point on the seismic coupling in hard rock. Existing data can be explained if ice controls the sliding friction on preexisting cracks.
Shear Wave Generation From Contained Explosions
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Author :
language : en
Publisher:
Release Date : 1996
Shear Wave Generation From Contained Explosions written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with categories.
The usefulness of the amplitude ratio of seismic phases such as Lg/P, as well as the ratio of magnitudes to discriminate explosions from earthquakes depends, in part, on the efficiency of shear wave production from seismic sources. We are studying shear wave generation at the source, initially from explosions within limestone blocks. Initially the samples are subjected to hydrostatic stress. However, we will be able to also simulate tectonic strain energy release in future experiments. Using a 1.6m long, 0.8m diameter sample subjected to an ambient pressure of up to 1 MPa, with a centrally placed explosive source, we propose to study the amplitude of shear wave generation of stress wave induced radial cracking in symmetric and asymmetric cavities. In unstressed rock, this shear wave production is expected to be controlled in part by the natural anisotropy of the rock. We expect to measure the SIP ratio from tamped explosions using (0.2 to 2 gram charges). Later tests will be conducted in partially decoupled asymmetric cavities, and the resultant shear wave radiation pattern will be compared to previous detailed finite element calculations of P and S wave radiation versus frequency and angle for elliptical cavities of aspect ratios in the range of 1:3 to 1:10. In order to measure the P and S waves generated from explosions, we developed a measurement method that is given in detail in this report. The initial test results for the tamped and decoupled explosions in cylindrical cavities in limestone show that the amplitude of SV/P for the decoupled experiment in limestone is -0.7, whereas it varies over a range of -1 to 3 for overdriven cavities, depending on angle from the cylindrical axis. Moreover, tensional cracks are generated in these cavities which resemble those inferred to have occurred in a similar geometry in the Sterling experiment.
Generation Of High Frequency P And S Wave Energy By Rock Fracture During A Buried Explosion
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Author :
language : en
Publisher:
Release Date : 2007
Generation Of High Frequency P And S Wave Energy By Rock Fracture During A Buried Explosion written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
The micromechanical damage mechanics developed by Ashby and Sammis (1990) was used to explore the effects of rock fracture on the seismic coupling of explosions. An important focus was the effect of ice in the fractures. The main effect of ice in the cracks of crystalline rock is to bridge the existing cracks forming a larger number of smaller cracks. Ice also increases the coefficient of friction on the cracks resulting in a significant increase in both elastic stiffness and fracture strength, both of which are temperature and strain-rate dependent. The damage mechanics model was used to interpret laboratory data on frozen rock and a field experiment in which chemical explosions were detonated above and below the permafrost layer in Alaska to directly observe the effect of ice in rock on the seismic coupling. Finally, we used the equivalent elastic medium model for an explosive source developed by Johnson and Sammis (2001) to explore the effect of an increase in both elastic stiffness and compressive strength on the amplitude of far-field seismic radiation. Our conclusion is that an explosion in frozen rock should have a smaller apparent yield than the same explosion in rock at temperatures above the freezing point and that the effect should be larger in limestone than in granite.
Seismological Research Letters
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Author :
language : en
Publisher:
Release Date : 2006
Seismological Research Letters written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Earthquakes categories.
Wave Generation From Explosions In Cavities In Rock
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Author :
language : en
Publisher:
Release Date : 1998
Wave Generation From Explosions In Cavities In Rock written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with categories.
We have developed a measurement mehtod to monitor P- and S-waves generated from laboratory-scale explosions in meter-sized rock media at a series of stations, and invented a unique device to drill spherical cavities with diameters of up to 10 cm in rock. We have also conducted laboratory experiments in which spherical/cylindrical charges of 0.2 to 1.9 g mass were detonated at the center of spherical/cylindrical cavities with radii from 0.6 to 1.5 cm in Bedford limestone and the waves generated by the explosions were recorded in the near field within 250 mm. The reccords and post-explosion studies clearly demonstrate the P-waves generated from both explosions in cavities and crack propagation in rock. The peak particle displacement induced by P-waves ranges from 9 to 15 um at 150 to 210 mm from the source for the spherical cavity experiment with 1.9 g explosives, and 8 to 4 um at 150 to 220 mm from the source with 0.8 g explosives, 35 to 10 um at 150 to 240 mm for the tamped cylindrical cavity experiment with 1.2 g explosives and 7 to 2 um at 150 to 190 mm from the source for the decoupled cylindrical cavity experiment with 0.24 g explosives.
Nuclear Science Abstracts
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Author :
language : en
Publisher:
Release Date : 1974
Nuclear Science Abstracts written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1974 with Nuclear energy categories.
Kwic Index Of Rock Mechanics Literature
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Author : J P Jenkins
language : en
Publisher: Elsevier
Release Date : 2016-06-03
Kwic Index Of Rock Mechanics Literature written by J P Jenkins and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-06-03 with Technology & Engineering categories.
KWIC Index of Rock Mechanics Literature, Part 2: 1969-1976 is an index of subjects in rock mechanics. The KWIC (keyword-in-context) index is produced by cyclic permutation of significant words in the title of the publication. The text covers materials in rock mechanics and geomechanics published around the 70s. The book will be of great use to students, researchers, and practitioners of geological sciences.
Industrial Communication Technology Handbook Second Edition
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Author : Richard Zurawski
language : en
Publisher: CRC Press
Release Date : 2014-11-07
Industrial Communication Technology Handbook Second Edition written by Richard Zurawski and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-11-07 with Technology & Engineering categories.
Featuring contributions from major technology vendors, industry consortia, and government and private research establishments, the Industrial Communication Technology Handbook, Second Edition provides comprehensive and authoritative coverage of wire- and wireless-based specialized communication networks used in plant and factory automation, automotive applications, avionics, building automation, energy and power systems, train applications, and more. New to the Second Edition: 46 brand-new chapters and 21 substantially revised chapters Inclusion of the latest, most significant developments in specialized communication technologies and systems Addition of new application domains for specialized networks The Industrial Communication Technology Handbook, Second Edition supplies readers with a thorough understanding of the application-specific requirements for communication services and their supporting technologies. It is useful to a broad spectrum of professionals involved in the conception, design, development, standardization, and use of specialized communication networks as well as academic institutions engaged in engineering education and vocational training.