Measurements of wave processes in isotropic and transversely isotropic elastic rocks

Krishnan, Krishnamoorthy; Goldsmith, Werner; Sackman, Jerome L.

doi:10.1016/0148-9062(74)92074-9

Cited by 3 publications

(3 citation statements)

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“…It should be noted that among the efforts due to the complexity of problems and the limitation in experiments, the knowledge we have learned about wave propagations in rocks is mainly focused on a few measurable characteristics and their relationships with the properties of intact rocks including strength, density, Young's modulus, Poison's ratio, porosity, the property of gas/liquid inclusions and joint geometry [2,6,[8][9][10][11][12][13][14] . Little work has been done regarding the experimental proofs of how the substructures react, what happens between the substructures and the involved gas/liquid phases, and how the coupling mechanism affects the external performance of porous media during wave transmissions.…”

Section: Introductionmentioning

confidence: 99%

Laboratory investigation on mechanisms of stress wave propagations in porous media

Yang

Yan-zhe³

et al. 2009

Sci. China Ser. E-Technol. Sci.

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A number of porous models having the similar statistical characteristics of pores and physical properties with natural sandstones have been produced using reactive powder concrete (RPC) and polystyrenes. Spit-Hopkinson-Pressure -Bar tests and CT scans have been carried out on the models with the various porosities to probe the performance of wave propagations and the responses of pores and the matrix during wave propagations. It is shown that porosities significantly influence wave propagations. For an identical impact strain rate, the greater the porosity is, the larger the amplitude of the reflected wave appears, the more the peak in the reflected wave presents, and the smaller the amplitude of the transmitted wave turns out. A single peak emerges in the reflected wave when the porosity falls down to 5%. The larger the impact strain rate, the much remarkable the phenomena. The energy-dissipated ratio of porous models, i.e., W J /W I , linearly increases with the increment of porosities. The ratio is sensitive to the impact strain rate. Differences in the performance of wave propagations and energy dissipation result from the varied mechanisms that pores response to impacts. For the porosity less than 10%, the mechanism appears to be a process fracturing the matrix to generate new surfaces or pores. Energy has primarily been dissipated in creating new surfaces or pores. No apparent pore deformation takes place. The impact strain rate takes little effect on pore geometry. For the porosity of 15% or more, the mechanism works depending on the impact strain rate. When a low impact strain rate applies, the mechanism still appears to crack the matrix to generate surfaces or pores, but the amount is lower as compared to the case with a low porosity. If a large impact stain rate applies, the mechanism combines both fracturing the matrix and deforming the pores, with the deforming pores predominating. The vast majority of energy has been dissipated to deform pores. Only high porosity and impact strain rate can bring significant deformation to the pores. The proposed eccentricity of pores is capable of characterizing the geometry of pores and its change during wave propagations.

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Section: Introductionmentioning

confidence: 99%

Laboratory investigation on mechanisms of stress wave propagations in porous media

Yang

Yan-zhe³

et al. 2009

Sci. China Ser. E-Technol. Sci.

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“…Due to the large population and complex and disordered spatial distribution of pores, it is extremely difficult to theoretically correlate the stress motion, constitutive equations and energy accumulation and dissipation in rock or rock masses with lithology, pore structure characteristics and deformation properties [13][14][15][16][17][18][19][20]. Alternatively, laboratory or field tests and numerical simulation are more commonly adopted to analyze stress wave propagation in natural porous rock or rock masses [21][22][23][24][25][26][27][28][29][30][31][32]. Undoubtedly, the studies are valuable and helpful for better understanding the law of wave propagation and attenuation in rocks, deformation and failure mechanisms, and triggering mechanism of dynamic disasters.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of mechanisms of deformation, failure and energy dissipation in porous rock media subjected to wave stresses

Wang

Yang

et al. 2010

Sci. China Technol. Sci.

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The pore characteristics, mineral compositions, physical and mechanical properties of the subarkose sandstones were acquired by means of CT scan, X-ray diffraction and physical tests. A few physical models possessing the same pore characteristics and matrix properties but different porosities compared to the natural sandstones were developed. The 3D finite element models of the rock media with varied porosities were established based on the CT image processing of the physical models and the MIMICS software platform. The failure processes of the porous rock media loaded by the split Hopkinson pressure bar (SHPB) were simulated by satisfying the elastic wave propagation theory. The dynamic responses, stress transition, deformation and failure mechanisms of the porous rock media subjected to the wave stresses were analyzed. It is shown that an explicit and quantitative analysis of the stress, strain and deformation and failure mechanisms of porous rocks under the wave stresses can be achieved by using the developed 3D finite element models. With applied wave stresses of certain amplitude and velocity, no evident pore deformation was observed for the rock media with a porosity less than 15%. The deformation is dominantly the combination of microplasticity (shear strain), cracking (tensile strain) of matrix and coalescence of the cracked regions around pores. Shear stresses lead to microplasticity, while tensile stresses result in cracking of the matrix. Cracking and coalescence of the matrix elements in the neighborhood of pores resulted from the high transverse tensile stress or tensile strain which exceeded the threshold values. The simulation results of stress wave propagation, deformation and failure mechanisms and energy dissipation in porous rock media were in good agreement with the physical tests. The present study provides a reference for analyzing the intrinsic mechanisms of the complex dynamic response, stress transit mode, deformation and failure mechanisms and the disaster mechanisms of rock media. porous media, three-dimensional finite element model, rock media, stress wave, failure mechanism, energy dissipation Citation: JU Y, Wang H J, Yang Y M, et al. Numerical simulation of mechanisms of deformation, failure and energy dissipation in porous rock media subjected to wave stresses.

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“…These included strain gages and piezoelectric crystals embedded in three-dimensional models (9,12). In this type of work, he was always trying to extract sound experimental data and then fit this with the best available theories, or developing them himself (13)(14)(15)(16)(17). During this time, he became interested in geophysical applications of impact and studied wave propagation phenomena in rock and concrete Figure 3 Goldsmith in his Wave Propagation and Impact Laboratory in Etcheverry Hall on the Berkeley campus preparing for an impact experiment, of the kind that he performed countless times.…”

Section: Scholarly Contributionsmentioning

confidence: 99%

Untitled

2005

Annu. Rev. Biomed. Eng.

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Werner Goldsmith, one of the foremost authorities on the mechanics of impact and the biomechanics of head and neck injuries, died peacefully at home in Oakland, California, on August 23, 2003, at age 79 after a short, courageous battle with leukemia, ending a long and very distinguished career in mechanics, dynamics, and biomechanics, and an almost six-decades-long association with the University of California, Berkeley. He was one of the pioneering, eminent solid and fluid mechanicians who made an early transition to biomechanics, and in rising to equal distinction in their new fields, added great credibility to biomechanics as a discipline in its own right. He was also a distinguished and influential figure in bioengineering education at his own institution, and, more broadly, in the United States and abroad. An emeritus professor for over a decade, he continued to be active in research and teaching until the very last days of his life.

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Measurements of wave processes in isotropic and transversely isotropic elastic rocks

Cited by 3 publications

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Laboratory investigation on mechanisms of stress wave propagations in porous media

Laboratory investigation on mechanisms of stress wave propagations in porous media

Numerical simulation of mechanisms of deformation, failure and energy dissipation in porous rock media subjected to wave stresses

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