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in creator/contributor: "Berge, P A"

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Constraints on Elastic Parameters and Implications for Lithology on Vti Media

Energy considerations provide constraints on elastic stiffnesses in media exhibiting transverse isotropy with a vertical axis of symmetry. If the anisotropy is due to thin layers, additional constraints hold. The constraints can be used to provide insight into the mechanisms causing the anisotropy, which in turn gives information about the lithology. These ideas are illustrated by some examples of anisotropic sedimentary rocks and sediments from the literature.

Date: June 2, 1995

Creator: Berge, P. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Seismic Velocities Contain Information About Depth, Lithology, Fluid Content, and Microstructure

Recent advances in field and laboratory methods for measuring elastic wave velocities provide incentive and opportunity for improving interpretation of geophysical data for engineering and environmental applications. Advancing the state-of-the-art of seismic imaging requires developing petrophysical relationships between measured velocities and the hydrogeology parameters and lithology. Our approach uses laboratory data and rock physics methods. Compressional (Vp) and shear (Vs) wave velocities… more

Date: January 3, 2002

Creator: Berge, P A & Bonner, B P

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Pore compressibility in rocks

The unjacketed core compressibility in a porous rock is the change in pore volume due to change in pore pressure for constant differential pressure. This parameter affects how the saturated bulk modulus of a rock is related to the drained frame modulus and the pore fluid compressibility. Recent measurements of poroelastic constants and effective medium theories are used to estimate how the pore compressibility depends on effective stress and how uncertainty in the pore compressibility affects u… more

Date: June 5, 1998

Creator: Berge, P A

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Effect of Radiation on Topopah Spring Tuff Mechanical Properties

The effect of radiation on the mechanical properties of Topopah Spring tuff was investigated by performing uniaxial compressive tests on irradiated and control samples of the tuff from the potential repository horizon at Yucca Mountain. Test results are presented, including stress-strain curves and peak strength and Young`s modulus values. These results show that for homogeneous uncracked samples of Topopah Spring tuff, exposure to gamma radiation had no discernible effect on the unconfined par… more

Date: November 1, 1996

Creator: Berge, P. A. & Blair, S. C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Uniaxial Compression Behavior of Small Blocks of Welded Tuff

Laboratory compression tests have been conducted on small block samples of Topopah Spring Tuff to investigate the scale dependence of geomechanical properties. These tests are the first of a series of tests designed to study coupled processes in the near-field environment of a nuclear waste repository. This paper presents new deformation and elastic wave velocity data.

Date: November 16, 1995

Creator: Blair, S. C. & Berge, P. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Analysis of Thomsen Parameters for Finely Layered Vti Media

The range of Thomsen`s anisotropy parameters {epsilon} and {delta} for vertical transversely isotropic (VTI) media when the anisotropy is due to fine layering of isotropic elas-tic materials is considered. We show that {epsilon} lies in the range -3/8 {<=} {epsilon} {<=} {1/2}[<v{sub p}{sup 2}><v{sup p}{sup -2}>-1], for finely lay-ered media having constant density; smaller positive and all negative values of {epsilon} occur for media with large fluctuations in the Lam{acute e} parameter {lambd… more

Date: April 1, 1997

Creator: Berryman, J. G. & Berge, P. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Measuring geomechanical properties of Topopah Spring Tuff at the 1-meter scale

The Yucca Mountain Site Characterization Project is studying physical and chemical properties of Topopah Spring tuff and coupled thermal, mechanical, hydrological, and geochemical processes expected in the near-field environment of the potential waste repository at Yucca Mountain, Nevada. Investigating the suitability of Topopah Spring tuff as a host rock for radioactive waste disposal includes measuring mechanical properties. Since heterogeneities vary with scale, from vugs and cracks at the h… more

Date: November 1, 1994

Creator: Blair, S. C. & Berge, P. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Joint inversion of geophysical data for site characterization and restoration monitoring

The purpose of this project is to develop a computer code for joint inversion of seismic and electrical data, to improve underground imaging for site characterization and remediation monitoring. The computer code developed in this project will invert geophysical data to obtain direct estimates of porosity and saturation underground, rather than inverting for seismic velocity and electrical resistivity or other geophysical properties. This is intended to be a significant improvement in the state… more

Date: May 28, 1998

Creator: Berge, P. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Compressional and Shear Wave Velocities for Artifical Granular Media Under Simulated Near Surface Conditions

No Description Available.

Date: March 18, 2001

Creator: Bonner, B P; Berge, P A & Wildenschild, D

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Rock Physics Interpretation of P-Wave Q and Velocity Structure, Geology, Fluids and Fractures at the Southeast Portion of The Geysers Geothermal Reservoir

We examine how quantitative rock physics models, such as effective medium theories, can improve the interpretation of seismic parameters and material and fluid properties at The Geysers. We use effective medium theories to estimate effects of fractures on velocities for The Geysers rocks. We compare theoretical velocity estimates to laboratory measurements from the literature and our seismic velocity values from 1992 earthquake data. We approximate the reservoir as being homogeneous in mineral … more

Date: April 6, 2001

Creator: Berge, P; Hutchings, L; Wagoner, J & Kasameyer, P

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Laboratory Measurements of Velocity and Attenuation in Sediments

Laboratory measurements are required to establish relationships between the physical properties of unconsolidated sediments and P- and S-wave propagation through them. Previous work has either focused on measurements of compressional wave properties at depths greater than 500 m for oil industry applications or on measurements of dynamic shear properties at pressures corresponding to depths of less than 50 m for geotechnical applications. Therefore, the effects of lithology, fluid saturation, an… more

Date: June 8, 2004

Creator: Zimmer, M A; Berge, P A; Bonner, B P & Prasad, M

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Geomechanical Analysis of the Large Block Test

The Yucca Mountain Site Characterization Project is investigating the Topopah Spring tuff at Yucca Mountain, Nevada, to determine whether it is suitable as a host rock for the disposal of high-level nuclear wastes. The Large Block Test (LBT) at Fran Ridge was planned as part of the project to investigate coupled thermal-mechanical-hydrological and geochemical processes that may occur in the repository near-field environment. This test would be performed on an excavated block of Topopah Spring t… more

Date: August 1, 1996

Creator: Blair, S. C.; Berge, P. A. & Wang, H. F.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Using Laboratory Measurements of Electrical and Mechanical Properties to Assist Interpretation of Field Data from Shallow Geophysical Measurements

Reconstruction of shallow subsurface structure from geophysical data is a central problem for many environmental and engineering applications. We observe that for shallow soil distributions, seismic data alone or electrical data alone may provide a good reconstruction of the subsurface. We show that using joint seismic and electrical data will improve the reconstruction of shallow structure. Our results emphasize that the availability of techniques for making laboratory measurements of ultrason… more

Date: November 30, 2001

Creator: Bertete-Aguirre, H.; Berge, P. A. & Roberts, J. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Two-point correlation functions to characterize microgeometry and estimate permeabilities of synthetic and natural sandstones

We have developed an image-processing method for characterizing the microstructure of rock and other porous materials, and for providing a quantitative means for understanding the dependence of physical properties on the pore structure. This method is based upon the statistical properties of the microgeometry as observed in scanning electron micrograph (SEM) images of cross sections of porous materials. The method utilizes a simple statistical function, called the spatial correlation function, … more

Date: August 1, 1993

Creator: Blair, S. C.; Berge, P. A. & Berryman, J. G.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Laboratory Velocity Measurements Used for Recovering Soil Distributions from Field Seismic Data

Recent advances in field methods make it possible to obtain high quality compressional (P) and shear (S) velocity data for the shallow subsurface. Environmental and engineering problems require new methods for interpreting the velocity data in terms of sub-surface soil distribution. Recent advances in laboratory measurement techniques have provided high quality velocity data for soils at low pressures that can be used to improve interpretation of field data. We show how laboratory data can be u… more

Date: October 20, 1999

Creator: Berge, P A & Bertete-Aguirre, H

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Compressional and Shear Wave Velocities for Artificial Granular Media Under Simulated Near Surface Conditions

Laboratory ultrasonic experiments were made on artificial soil samples in order to observe the effects of slight overburden, sand/clay ratio and pore fluid saturation on compressional and shear wave velocities. Up to several meters of overburden were simulated by applying low uniaxial stress of about 0.1 MPa to a restrained sample. Samples were fabricated from Ottawa sand mixed with a swelling clay (Wyoming bentonite). The amount of clay added was 1 to 40 percent by mass. Most measurements were… more

Date: September 9, 2001

Creator: Bonner, B. P.; Berge, P. A. & Wildenschild, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Scalar Properties of Transversely Isotropic Tuff From Images of Orthogonal Cross Sections

Image processing methods have been used very effectively to estimate physical properties of isotropic porous earth materials such as sandstones. Anisotropic materials can also be analyzed in order to estimate their physical properties, but additional care and a larger number of well-chosen images of cross sections are required to obtain correct results. Although low-symmetry anisotropic media present difficulties for two-dimensional image processing methods, geologic materials are often transve… more

Date: January 1, 1997

Creator: Berge, P. A.; Berryman, J. G.; Blair, S. C. & Pena, C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Deformation and Velocity Measurements at Elevated Temperature in a Fractured 0.5 M Block of Tuff

This paper presents preliminary results of laboratory tests conducted on small block samples of Topopah Spring tuff, in support of the Yucca Mountain Site Characterization Project. The overall objective of these tests is to investigate the thermal-mechanical, thermal-hydrological, and thermal-chemical response of the rock to conditions similar to the near-field environment (NFE) of a potential nuclear waste repository. We present preliminary results of deformation and elastic wave velocity meas… more

Date: February 1, 1996

Creator: Blair, S. C. & Berge, P. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Geomechanics investigations in support of the large block test at Fran Ridge, Nye County, Nevada.

The Yucca Mountain Site Characterization Project is investigating the Topopah Spring Tuff at Yucca Mountain, Nevada for its suitability as a host rock for the disposal of high level nuclear wastes. The Lawrence Livermore National Laboratory is planning a large block test (LBT) to investigate coupled thermal-mechanical-hydrological and geochemical processes that may occur in the repository near-field environment.

Date: July 21, 1994

Creator: Blair, S.C.; Berge, P.; Kansa, E.; Lin, Wunan & Roberts, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Poroelasticity of rock

Poroelasticity is the theoretical framework used to describe the coupled processes which occur when a fluid bearing porous material is deformed by a stress field. The theoretical basis for the treatment of problems in poroelasticity has been derived in an extensive body of work over the last fifty years, most notably by Biot. Many of Biot`s successors have attempted to find relationships between the physical properties of the material to be analyzed and the Biot coefficients. Our approach to th… more

Date: May 13, 1993

Creator: Bonner, B. P.; Berge, P. A.; Berryman, J. G. & Wang, H. F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Nanosecond Ultrasonics to Study Phase Transitions in Solid and Liquid Systems at High Pressure and Temperature

This report describes the development of a high-frequency ultrasonic measurement capability for application to the study of phase transitions at elevated pressure and temperature. We combined expertise in various aspects of static high-pressure technique with recent advances in wave propagation modeling, ultrasonic transducer development, electronic methods and broadband instrumentation to accomplish the goals of this project. The transduction and electronic systems have a demonstrated bandwidt… more

Date: March 21, 2007

Creator: Bonner, B P; Berge, P A; Carlson, S C; Farber, D L & Akella, J

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Thermomechanical effects on permeability for a 3-D model of YM rock

The authors estimate how thermomechanical processes affect the spatial variability of fracture permeability for a 3-D model representing Topopah Spring tuff at the nuclear-waste repository horizon in Yucca Mountain, Nevada. Using a finite-difference code, they compute thermal stress changes. They evaluate possible permeability enhancement resulting from shear slip along various mapped fracture sets after 50 years of heating, for rock in the near-field environment of the proposed repository. The… more

Date: January 12, 1999

Creator: Berge, P A; Blair, S C & Wang, H F

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Estimated bounds on rock permeability changes from THM Processes

We performed THM modeling to estimate bounds on permeability changes in the NFE. For our modeling, we used the TM three-dimensional (3-D) finite-difference code FLAC{sup 3D} version 2.0 (Itasca Consulting Group Inc. 1997) to compute changes in stress and displacement in an elastic model subjected to temperature changes over time. Output from TH modeling (Hardin et al., 1998, Chapter 3) using the code NUFT (Nitao 1993) provided the temperature changes for input to FLAC{sup 3D}. We then estimated… more

Date: August 1, 1998

Creator: Berge, P A; Blair, S C & Wang, H F

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Effect of Radiation on the Mechanical Properties of Topopah Spring Tuff

This report presents results of a suite of uniaxial compressive tests conducted to provide laboratory data to determine how radiation affects the compressive strength of Topopah Spring Tuff, which is the rock type for the proposed geologic repository at Yucca Mountain, in Nevada. The repository would be designed for storing spent fuel and other high-level radioactive wastes. We need to better understand what effect radiation has on the compressive strength of this type of rock because emplaceme… more

Date: June 4, 1996

Creator: Blair, S. C.; Kelly, J. M.; Pine, O.; Pletcher, R. & Berge, P. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department