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Title: Experimental and Analytical Research on Fracture Processes in ROck

Abstract

Experimental studies on fracture propagation and coalescence were conducted which together with previous tests by this group on gypsum and marble, provide information on fracturing. Specifically, different fracture geometries wsere tested, which together with the different material properties will provide the basis for analytical/numerical modeling. INitial steps on the models were made as were initial investigations on the effect of pressurized water on fracture coalescence.

Authors:
; ;
Publication Date:
Research Org.:
Massachusetts Institute of Technologyh
Sponsoring Org.:
USDOE Office of Geothermal Technologies (EE-2C)
OSTI Identifier:
948451
Report Number(s):
DOE/GO/16061-1
TRN: US201106%%845
DOE Contract Number:
FG36-06GO16061
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; COALESCENCE; FRACTURES; FRACTURING; GYPSUM; MARBLE; SIMULATION; WATER; Fractures; crack coalescence; granite; pressurized water

Citation Formats

Herbert H.. Einstein, Jay Miller, and Bruno Silva. Experimental and Analytical Research on Fracture Processes in ROck. United States: N. p., 2009. Web. doi:10.2172/948451.
Herbert H.. Einstein, Jay Miller, & Bruno Silva. Experimental and Analytical Research on Fracture Processes in ROck. United States. doi:10.2172/948451.
Herbert H.. Einstein, Jay Miller, and Bruno Silva. Fri . "Experimental and Analytical Research on Fracture Processes in ROck". United States. doi:10.2172/948451. https://www.osti.gov/servlets/purl/948451.
@article{osti_948451,
title = {Experimental and Analytical Research on Fracture Processes in ROck},
author = {Herbert H.. Einstein and Jay Miller and Bruno Silva},
abstractNote = {Experimental studies on fracture propagation and coalescence were conducted which together with previous tests by this group on gypsum and marble, provide information on fracturing. Specifically, different fracture geometries wsere tested, which together with the different material properties will provide the basis for analytical/numerical modeling. INitial steps on the models were made as were initial investigations on the effect of pressurized water on fracture coalescence.},
doi = {10.2172/948451},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Feb 27 00:00:00 EST 2009},
month = {Fri Feb 27 00:00:00 EST 2009}
}

Technical Report:

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  • Analytical solutions based on the Laplace and Fourier transformation techniques are derived for the transient advective-dispersive transport of a single radionuclide through fractures (two-dimensional analysis) and rock (one-dimensional analysis). The longitudinal dispersion-free solution is also reported. The geometry considered consists of either a single planar fracture (infinite diffusion in the rock) or a system of equidistant parallel fracture planes with uniform aperture (finite diffusion in the rock). The solution assumes that the ground-water flow regime is under steady-state and isothermal conditions, and the streamlines along the direction of flow are parallel. The solution related to the single fracture case wasmore » verified by comparing its performance with available results from other works. Two sets of solutions were derived for the multiple parallel fracture case; the first, based on a series approximation, and the second, based on contour integration, were designed to cope efficiently with small and large Fourier numbers, respectively. The general solution requires, in both cases, the evaluation of a single integral, except in the case of the solution based on contour integration, where an additional one is required. This is performed using a Gauss-Legendre quadrature scheme. 34 refs., 65 figs., 77 tabs.« less
  • For Oak Ridge National Lab., TN. The ability ot a pressure vessel steel to resist fracture constitutes an important factor in ensuring nuclear reactor safety. Fracture mechanics is considered as providing the best general approach to understanding the brittle fracture phenomenon in reactor vessel steels. A comprehensive program to apply ihe technology of both linear elastic and elastic- plastic fracture mechanics to all foreseeable brittle and ductile failure aspects of heavy-walled nuclear pressure vessels is being developed. One important aspect of this program is the extension of linear elastic fracture mechanics concepts to the realm of elastic-plastic fracture mechanics technology.more » The application of the two leading theories of elastic-pla stic fracture (J-Integral and Equivalent Energy) to a relatively simple test specimen geometry, using a two- dimensional, finite element computer program which is general enough to-be applied later to more complex reactor vessel problems is reported. (TFD)« less
  • Dynamic photoelastic and high-speed photographic techniques are used to investigate the phenomena related to fracture in brittle materials by water jet. Two water jet devices were used. A continuous water jet producing jet velocities up to 230/msec was used to study the long-time phenomena using a framing camera operating at 8,000 frames per sec. The short-time phenomena were studied by using a device for explosively propelling high-speed water jets. Several nozzle geometries with varying explosive charges were used. Jet velocities ranging between 700/msec and 2,800/msec were obtained.
  • The objective of this investigation is to determine the effectiveness of cement grouts as sealants of fractures in rock. Laboratory experiments have been conducted on seven 15-cm granite cubes containing saw cuts, three 23-cm diameter andesite cores containing induced tension cracks, and one 15-cm diameter marble core containing a natural fracture. Prior to grouting, the hydraulic conductivity of the fractures is determined under a range of normal stresses, applied in loading and unloading cycles, from 0 to 14 MPa (2000 psi). Grout is injected through an axial borehole, at a pressure of 1.2 to 8.3 MPa (180 to 1200 psi),more » pressure selected to provide a likely groutable fracture aperture, while the fracture is stressed at a constant normal stress. The fracture permeability is measured after grouting. Flow tests on the ungrouted samples confirm the inverse relation between normal stress and fracture permeability. The equivalent aperture determined by these tests is a reliable indicator of groutability. Postgrouting permeability measurements as performed here, and frequently in practice, can be misleading, since incomplete grouting of fractures can result in major apparent reductions in permeability. The apparent permeability reduction is caused by grouting of a small area of a highly preferential flowpath directly adjacent to the hole used for grouting and for permeability testing. Experimental results confirm claims in the literature that ordinary portland cement inadequately penetrates fine fractures.« less
  • The results of flexural tests on granite, marble, gneiss, and schist beams are presented in terms of the maximum stress and the work expended to cause failure. The extent of side cracking is measured by quantitative microscopy and is used to calculate a corrected fracture surface work. Thermal cycling of unnotched beams to 540$C, 1,280$C, and 1,800$C is found to cause extensive cracking and the resulting decrease to strength can be measured. The use of surface-active agents to reduce the work necessary to cause failure is found effective. A one percent water solution of aluminum chloride at 90$C produces amore » 50% reduction in the fracture surface work value of granite, compared to the room temperature dry condition. A mechanism of stress-activated corrosion may be the principal cause fo this reduction in strength.« less