25 Matching Results

Search Results

Advanced search parameters have been applied.

Quasi-static strength and creep deformational characteristics of bedded salt from the Carey mine near Lyons, Kansas

Description: This report presents the results of a laboratory effort which was undertaken to determine mechanical properties of salt from Lyons, Kansas. Another goal of the experimental work was to define testing procedures, calibrations and data reduction during the process of generating strength data. Mechanical properties such as modulus of deformation and principal strain ratio were incorporated into simulations of Project Salt Vault using finite element methods. Deformational behavior of Lyons salt subjected to constant stress levels for extended periods of time was also evaluated in this experimental effort and compared to results determined for salt from other locations. Strength data and empirical relationships of strain as a function of time, stress and temperature were reduced for application to finite element analyses.
Date: October 13, 1978
Creator: Hansen, F.D.
Partner: UNT Libraries Government Documents Department

Mechanical excavator performance in Yucca Mountain tuffs

Description: A research effort of four phases is in progress at the Colorado School of Mines. The overall program will evaluate the cutability of welded tuff and other lithologies likely to be excavated at Yucca Mountain in the site characterization process. Several mechanical systems are considered with emphasis given to the tunnel boring machine. The research comprises laboratory testing, linear drag bit and disc cutter tests and potentially large-scale laboratory demonstrations to support potential use of a tunnel boring machine in welded tuff. Preliminary estimates of mechanical excavator performance in Yucca Mountain tuff are presented here. As phases of the research project are completed, well quantified estimates will be made of performance of mechanical excavators in the Yucca Mountain tuffs. 3 refs., 2 tabs.
Date: January 1, 1991
Creator: Ozdemir, L. & Hansen, F.D.
Partner: UNT Libraries Government Documents Department

Creep behavior of bedded salt from southeastern New Mexico at elevated temperature

Description: Results of a series of triaxial creep experiments conducted on bedded salt specimens from ERDA Hole 9 in southeastern New Mexico are presented. The purpose of the experiments was to measure creep response of salt at temperatures of 24, 70, and 100/sup 0/C under confinement pressures of 0, 1500, 2000, 2500, and 3000 psi and differential axial stress levles of 1500, 3000, 4500, and 6000 psi. Test durations ranged from 15 minutes to over 500 hours. The specimens, obtained by recording 4-in.-dia cores in the axial direction, were nominally two inches in diameter and four inches in length. The crystal size ranged from very small to one-half inch diameter; the specimens contained various amounts of clay impurities. A total of 19 specimens were prepared of which 14 were tested. The collected data included axial and lateral strain, axial and confinement stresses, time and temperature. Periodically, axial stress was adjusted to account for specimen strain in order to maintain a constant differential stress. Frequency of the stress correction was dependent on the rate of deformation; two or more corrections in a 24-hour period were typical. Data were automatically recorded with a printer, manually recoded from the print-out to punched cards and reduced by means of a computer. A preponderance of the data was collected in the transient creep regime. In some tests specimen rupture occurred, while in others an accelerating creep rate brought the specimen in contact with the pressure vessel wall. Aslo, a considerable amount of data was collected during stress application to creep stress level.
Date: November 1, 1979
Creator: Hansen, F.D. & Mellegard, K.D.
Partner: UNT Libraries Government Documents Department

Thermomechanical properties of selected shales

Description: The experimental work discussed in this report is part of an ongoing program concerning evaluation of sedimentary and other rock types as potential hosts for a geologic repository. The objectives are the development of tools and techniques for repository characterization and performance assessment in a diversity of geohydrologic settings. This phase of the program is a laboratory study that investigates fundamental thermomechanical properties of several different shales. Laboratory experiments are intrinsically related to numerical modeling and in situ field experiments, which together will be used for performance assessment.
Date: August 1, 1987
Creator: Hansen, F.D. & Vogt, T.J.
Partner: UNT Libraries Government Documents Department

Large-scale dynamic compaction demonstration using WIPP salt: Fielding and preliminary results

Description: Reconsolidation of crushed rock salt is a phenomenon of great interest to programs studying isolation of hazardous materials in natural salt geologic settings. Of particular interest is the potential for disaggregated salt to be restored to nearly an impermeable state. For example, reconsolidated crushed salt is proposed as a major shaft seal component for the Waste Isolation Pilot Plant (WIPP) Project. The concept for a permanent shaft seal component of the WIPP repository is to densely compact crushed salt in the four shafts; an effective seal will then be developed as the surrounding salt creeps into the shafts, further consolidating the crushed salt. Fundamental information on placement density and permeability is required to ensure attainment of the design function. The work reported here is the first large-scale compaction demonstration to provide information on initial salt properties applicable to design, construction, and performance expectations. The shaft seals must function for 10,000 years. Over this period a crushed salt mass will become less permeable as it is compressed by creep closure of salt surrounding the shaft. These facts preclude the possibility of conducting a full-scale, real-time field test. Because permanent seals taking advantage of salt reconsolidation have never been constructed, performance measurements have not been made on an appropriately large scale. An understanding of potential construction methods, achievable initial density and permeability, and performance of reconsolidated salt over time is required for seal design and performance assessment. This report discusses fielding and operations of a nearly full-scale dynamic compaction of mine-run WIPP salt, and presents preliminary density and in situ (in place) gas permeability results.
Date: October 1, 1995
Creator: Ahrens, E.H. & Hansen, F.D.
Partner: UNT Libraries Government Documents Department

Database of Mechanical and Hydrological Properties of WIPP Anhydrite Derived from Laboratory-Scale Experiments

Description: The Department of Energy (DOE) has developed the Waste Isolation Pilot Plant (WIPP) for the purpose of demonstrating safe management, storage, and disposal of radioactive transuranic (TRU) waste generated by U.S. defense programs. The WIPP is located in southeastern New Mexico, and the underground facilities of the WIPP (i.e., experimental rooms, disposal rooms, etc.) are sited in the bedded salt of the Salado Formation at a depth of about 660 meters. The DOE has authorized the continuance of scientific research and engineering analysis related to the performance of the WIPP repository. One area of additional research relates to characterization of the mechanical and hydrological properties of anhydrite interbeds within the Salado Formation. These anhydrite interbeds have been penetrated by the shafts that provide access to the underground facilities and also lie in close proximity to the proposed radioactive waste disposal rooms at the repository horizon. Properties of particular interest are mechanical strength, deforrnational behavior, and fluid transport properties such as permeability. These properties will be used in calculationskmalyses of the mechanical and hydrological behavior of the anhydrite, in particular, and the shaft sealing system and disposal rooms, in general.
Date: October 1, 1998
Creator: Hansen, F.D. & Pfeifle, T.W.
Partner: UNT Libraries Government Documents Department

Large-scale dynamic compaction of natural salt

Description: A large-scale dynamic compaction demonstration of natural salt was successfully completed. About 40 m{sup 3} of salt were compacted in three, 2-m lifts by dropping a 9,000-kg weight from a height of 15 m in a systematic pattern to achieve desired compaction energy. To enhance compaction, 1 wt% water was added to the relatively dry mine-run salt. The average compacted mass fractional density was 0.90 of natural intact salt, and in situ nitrogen permeabilities averaged 9X10{sup -14}m{sup 2}. This established viability of dynamic compacting for placing salt shaft seal components. The demonstration also provided compacted salt parameters needed for shaft seal system design and performance assessments of the Waste Isolation Pilot Plant.
Date: May 1, 1996
Creator: Hansen, F.D. & Ahrens, E.H.
Partner: UNT Libraries Government Documents Department

Laboratory Characterization of Mechanical and Permeability Properties of Dynamically Compacted Crushed Salt

Description: The U. S. Department of Energy plans to dispose of transuranic wastes at the Waste Isolation Pilot Plant (WIPP), a geologic repository located at a depth of about 655 meters. The WIPP underground facility is located in the bedded salt of the Salado Formation. Access to the facility is provided through vertical shafts, which will be sealed after decommissioning to limit the release of hazardous waste from the repository and to limit flow into the facility. Because limited data are available to characterize the properties of dynamically compacted crushed salt, Sandia National Laboratories authorized RE/SPEC to perform additional tests on specimens of dynamically compacted crushed salt. These included shear consolidation creep, permeability, and constant strain-rate triaxial compression tests. A limited number of samples obtained from the large compacted mass were available for use in the testing program. Thus, additional tests were performed on samples that were prepared on a smaller scale device in the RE/SPEC laboratory using a dynamic-compaction procedure based on the full-scale construction technique. The laboratory results were expected to (1) illuminate the phenomenology of crushed-salt deformation behavior and (2) add test results to a small preexisting database for purposes of estimating parameters in a crushed-salt constitutive model. The candidate constitutive model for dynamically compacted crushed salt was refined in parallel with this laboratory testing.
Date: February 1, 1999
Creator: Hansen, F.D.; Mellegard, K.D. & Pfeifle, T.W.
Partner: UNT Libraries Government Documents Department

Crushed-salt constitutive model update

Description: Modifications to the constitutive model used to describe the deformation of crushed salt are presented in this report. Two mechanisms--dislocation creep and grain boundary diffusional pressure solutioning--defined previously but used separately are combined to form the basis for the constitutive model governing the deformation of crushed salt. The constitutive model is generalized to represent three-dimensional states of stress. New creep consolidation tests are combined with an existing database that includes hydrostatic consolidation and shear consolidation tests conducted on Waste Isolation Pilot Plant and southeastern New Mexico salt to determine material parameters for the constitutive model. Nonlinear least-squares model fitting to data from the shear consolidation tests and a combination of the shear and hydrostatic consolidation tests produced two sets of material parameter values for the model. The change in material parameter values from test group to test group indicates the empirical nature of the model but demonstrates improvement over earlier work with the previous models. Key improvements are the ability to capture lateral strain reversal and better resolve parameter values. To demonstrate the predictive capability of the model, each parameter value set was used to predict each of the tests in the database. Based on the fitting statistics and the ability of the model to predict the test data, the model appears to capture the creep consolidation behavior of crushed salt quite well.
Date: January 1, 1998
Creator: Callahan, G.D.; Loken, M.C.; Mellegard, K.D. & Hansen, F.D.
Partner: UNT Libraries Government Documents Department

Description and evaluation of a mechanistically based conceptual model for spall

Description: A mechanistically based model for a possible spall event at the WIPP site is developed and evaluated in this report. Release of waste material to the surface during an inadvertent borehole intrusion is possible if future states of the repository include high gas pressure and waste material consisting of fine particulates having low mechanical strength. The conceptual model incorporates the physics of wellbore hydraulics coupled to transient gas flow to the intrusion borehole, and mechanical response of the waste. Degraded waste properties using of the model. The evaluations include both numerical and analytical implementations of the conceptual model. A tensile failure criterion is assumed appropriate for calculation of volumes of waste experiencing fragmentation. Calculations show that for repository gas pressures less than 12 MPa, no tensile failure occurs. Minimal volumes of material experience failure below gas pressure of 14 MPa. Repository conditions dictate that the probability of gas pressures exceeding 14 MPa is approximately 1%. For these conditions, a maximum failed volume of 0.25 m{sup 3} is calculated.
Date: August 1, 1997
Creator: Hansen, F.D.; Knowles, M.K. & Thompson, T.W.
Partner: UNT Libraries Government Documents Department

Physical and mechanical properties of degraded waste surrogate material

Description: This paper discusses rock mechanics testing of surrogate materials to provide failure criteria for compacted, degraded nuclear waste. This daunting proposition was approached by first assembling all known parameters such as the initial waste inventory and rock mechanics response of the underground setting after the waste is stored. Conservative assumptions allowing for extensive degradation processes helped quantify the lowest possible strength conditions of the future state of the waste. In the larger conceptual setting, computations involve degraded waste behavior in transient pressure gradients as gas exits the waste horizon into a wellbore. Therefore, a defensible evaluation of tensile strength is paramount for successful analyses and intentionally provided maximal failed volumes. The very conservative approach assumes rampant degradation to define waste surrogate composition. Specimens prepared from derivative degradation product were consolidated into simple geometries for rock mechanics testing. Tensile strength thus derived helped convince a skeptical peer review panel that drilling into the Waste Isolation Pilot Plant (WIPP) would not likely expel appreciable solids via the drill string.
Date: March 1, 1998
Creator: Hansen, F.D. & Mellegard, K.D.
Partner: UNT Libraries Government Documents Department

Experiment and analysis comparison in support of the Yucca Mountain Project

Description: Sandia National Laboratories, as a participant in the Yucca Mountain Project, administered by the Nevada Operations Office of the US Department of Energy, is in the process of evaluating a proposed site for geologic disposal of high-level nuclear wastes in the volcanic tuffs at Yucca Mountain, Nevada. In a repository, loads will be imposed on the rock mass as a result of excavation of the openings and heating of the rock by the nuclear waste. In an attempt to gain a better understanding of the thermal, mechanical, and thermomechanical response of fractured tuff, a series of experiments have been performed, and measurements have been taken in the welded and nonwelded tuffs at the G-Tunnel underground test facility at Rainier Mesa, Nevada. Comparisons between measured and calculated data of the G-Tunnel High-Pressure Flatjack Development Experiment are presented in this investigation. Calculated results were obtained from two dimensional finite element analysis using a recently developed compliant-joint rock-mass model. The purpose of this work was to assess the predictive capability of the model based on limited material property data for the G-Tunnel welded tuff. The results of this evaluation are discussed.
Date: January 1, 1991
Creator: Chen, E.P.; Bauer, S.J.; Costin, L.S. & Hansen, F.D.
Partner: UNT Libraries Government Documents Department

Evaluation of constitutive models for crushed salt

Description: Three constitutive models are recommended as candidates for describing the deformation of crushed salt. These models are generalized to three-dimensional states of stress to include the effects of mean and deviatoric stress and modified to include effects of temperature, grain size, and moisture content. A database including hydrostatic consolidation and shear consolidation tests conducted on Waste Isolation Pilot Plant (WIPP) and southeastern New Mexico salt is used to determine material parameters for the models. To evaluate the capability of the models, parameter values obtained from fitting the complete database are used to predict the individual tests. Finite element calculations of a WIPP shaft with emplaced crushed salt demonstrate the model predictions.
Date: May 1, 1996
Creator: Callahan, G.D.; Loken, M.C.; Hurtado, L.D. & Hansen, F.D.
Partner: UNT Libraries Government Documents Department

Case studies of sealing methods and materials used in the salt and potash mining industries

Description: Sealing methods and materials currently used in salt and potash industries were surveyed to determine if systems analogous to the shaft seal design proposed for the Waste Isolation Pilot Plant (WIPP) exist. Emphasis was first given to concrete and then expanded to include other materials. Representative case studies could provide useful design, construction, and performance information for development of the WIPP shaft seal system design. This report contains a summary of engineering and construction details of various sealing methods used by mining industries for bulkheads and shaft liners. Industrial experience, as determined from site visits and literature reviews, provides few examples of bulkheads built in salt and potash mines for control of water. Sealing experiences representing site-specific conditions often have little engineering design to back up the methods employed and even less quantitative evaluation of seal performance. Cases examined include successes and failures, and both contribute to a database of experiences. Mass salt-saturated concrete placement under ground was accomplished under several varied conditions. Information derived from this database has been used to assess the performance of concrete as a seal material. Concrete appears to be a robust material with successes in several case studies. 42 refs.
Date: November 1995
Creator: Eyermann, T. J.; van Sambeek, L. L. & Hansen, F. D.
Partner: UNT Libraries Government Documents Department

Properties of dynamically compacted WIPP salt

Description: Dynamic compaction of mine-run salt is being investigated for the Waste Isolation Pilot Plant (WIPP), where compacted salt is being considered for repository sealing applications. One large-scale and two intermediate-scale dynamic compaction demonstrations were conducted. Initial fractional densities of the compacted salt range form 0.85 to 0.90, and permeabilities vary. Dynamically-compacted specimens were further consolidated in the laboratory by application of hydrostatic pressure. Permeability as a function of density was determined, and consolidation microprocesses were studied. Experimental results, in conjunction with modeling results, indicate that the compacted salt will function as a viable seal material.
Date: July 1, 1996
Creator: Brodsky, N.S.; Hansen, F.D. & Pfeifle, T.W.
Partner: UNT Libraries Government Documents Department

Variability in properties of Salado Mass Concrete

Description: Salado Mass Concrete (SMC) has been developed for use as a seal component in the Waste Isolation Pilot Plant. This concrete is intended to be mixed from pre-bagged materials, have an initial slump of 10 in., and remain pumpable and placeable for two hours after mixing. It is a mass concrete because it will be placed in monoliths large enough that the heat generated during cement hydration has the potential to cause thermal expansion and subsequent cracking, a phenomenon to avoid in the seal system. This report describes effects on concrete properties of changes in ratio of water to cement, batch size, and variations in characteristics of different lots of individual components of the concrete. The research demonstrates that the concrete can be prepared from laboratory-batched or pre-bagged dry materials in batches from 1.5 ft{sup 3} to 5.0 yd{sup 3}, with no chemical admixtures other than the sodium chloride added to improve bonding with the host rock, at a water-to-cement ratio ranging from 0.36 to 0.42. All batches prepared according to established procedures had adequate workability for at least 1.5 hours, and achieved or exceeded the target compressive strength of 4500 psi at 180 days after casting. Portland cement and fly ash from different lots or sources did not have a measurable effect on concrete properties, but variations in a shrinkage-compensating cement used as a component of the concrete did appear to affect workability. A low initial temperature and the water-reducing and set-retarding functions of the salt are critical to meeting target properties.
Date: August 1, 1995
Creator: Wakeley, L. D.; Harrington, P. T. & Hansen, F. D.
Partner: UNT Libraries Government Documents Department

Development of the Performance Confirmation Program at Yucca Mountain, Nevada

Description: The Yucca Mountain Performance Confirmation program consists of tests, monitoring activities, experiments, and analyses to evaluate the adequacy of assumptions, data, and analyses that form the basis of the conceptual and numerical models of flow and transport associated with a proposed radioactive waste repository at Yucca Mountain, Nevada. The Performance Confirmation program uses an eight-stage risk-informed, performance-based approach. Selection of the Performance Confirmation activities (a parameter and a test method) for inclusion in the Performance Confirmation program was done using a risk-informed performance-based decision analysis. The result of this analysis and review was a Performance Confirmation base portfolio that consists of 20 activities. The 20 Performance Confirmation activities include geologic, hydrologic, and construction/engineering testing. Several of the activities were initiated during site characterization and are ongoing. Others activities will commence during construction and/or post emplacement and will continue until repository closure.
Date: March 17, 2006
Creator: LeCain, G.D.; Barr, D.; Weaver, D.; Snell, R.; Goodin, S.W. & Hansen, F.D.
Partner: UNT Libraries Government Documents Department

Development of the Performance Confirmation Program at Yucca Mountain, Nevada

Description: The Yucca Mountain Performance Confirmation program consists of tests, monitoring activities, experiments, and analyses to evaluate the adequacy of assumptions, data, and analyses that form the basis of the conceptual and numerical models of flow and transport associated with a proposed radioactive waste repository at Yucca Mountain, Nevada. The Performance Confirmation program uses an eight-stage risk-informed, performance-based approach. Selection of the Performance Confirmation activities (a parameter and a test method) for inclusion in the Performance Confirmation program was done using a risk-informed performance-based decision analysis. The result of this analysis and review was a Performance Confirmation base portfolio that consists of 20 activities. The 20 Performance Confirmation activities include geologic, hydrologic, and construction/engineering testing. Several of the activities were initiated during site characterization and are ongoing. Others activities will commence during construction and/or post emplacement and will continue until repository closure.
Date: March 17, 2006
Creator: LeCain, G.D.; Snell, R.; Barr, D.; Goodin, S.W.; Weaver, D. & Hansen, F.D.
Partner: UNT Libraries Government Documents Department

Modeling of Human Intrusion Scenarios at the Waste Isolation Pilot Plant

Description: The Waste Isolation Pilot Plant is a mined, geologic repository designed for permanent disposal of transuranic waste. The facility is owned by the United States Department of Energy, and licensed for operations by the Environmental Protection Agency. Compliance with license requirements dictates that the repository must comply with regulatory stipulations that performance assessment calculations include the effects of resource exploitation on probable releases. Scenarios for these releases incorporate inadvertent penetration of the repository by an exploratory drilling operation. This paper presents the scenarios and models used to predict releases from the repository to the biosphere during. an inadvertent intrusion into the waste disposal regions. A summary of model results and conclusions is also presented.
Date: December 4, 1998
Creator: Gross, M.B.; Hansen, F.D.; Knowles, M.K.; Larson, K.W. & Thompson, T.W.
Partner: UNT Libraries Government Documents Department

Salt-saturated concrete strength and permeability

Description: Laboratory-scale experiments applicable to the use of salt-saturated concrete as a seal material for a transuranic waste repository have been completed. Nitrogen gas permeability measurements were made using a flexible-wall permeameter, a confining pressure of 1 MPa, and gas pressure gradients ranging from 0.3 MPa to 0.75 MPa. Results show that salt-saturated concrete has very low intrinsic permeability with values ranging from 9.4 {times} 10{sup {minus}22} m{sup 2} to 9.7 {times} 10{sup {minus}17} m{sup 2}. Strength and deformation characteristics were investigated under conditions of triaxial compression with confining pressures ranging from 0 to 15 MPa using either axial strain-rate or axial stress-rate control and show that the failure strength of concrete increases with confining pressure which can be adequately described through pressure-sensitive failure criteria. Axial, radial, and volumetric strains were also measured during each test and these data were used to determine elastic properties. Experimental results are applicable in the design and analysis of scale-related functions and apply to other concrete structures subjected to compressive loadings such as dams and prestressed structural members.
Date: November 1, 1996
Creator: Pfeifle, T.W.; Hansen, F.D. & Knowles, M.K.
Partner: UNT Libraries Government Documents Department

Dynamic compaction of salt: Initial demonstration and performance testing

Description: Reconsolidated crushed salt is proposed as the sole long-term shaft seal between the Waste Isolation Pilot Plant (WIPP) and the biosphere. The concept for a long-term shaft seal for the WIPP repository is to place crushed salt in the four shafts and to develop an effective seal as the surrounding salt creeps into the shafts, reconsolidating the salt. Permeability of the salt components is calculated to achieve performance objectives at some acceptable time in the future, an expectation which is a key to performance assessment calculations for the WIPP. Such a seal has never been constructed, and until now no performance measurements have been made on an appropriately large scale. A full understanding of construction methods, achievable initial density and permeability and time-wise performance of reconsolidating salt is required. This paper discusses nearly full-scale dynamic compaction of mine-run WIPP salt, preliminary measurements of density and permeability, and their variability within a relatively large volume of compacted material
Date: December 31, 1994
Creator: Hansen, F.D.; Ahrens, E.H.; Tidwell, V.C.; Tillerson, J.R & Brodsky, N.S.
Partner: UNT Libraries Government Documents Department

Review and perspectives on spallings release models in the 1996 performance assessment for the Waste Isolation Pilot Plant

Description: The Waste Isolation Pilot Plant was licensed for disposal of transuranic wastes generated by the US Department of Energy. The facility consists of a repository mined in a bedded salt formation, approximately 650 m below the surface. Regulations promulgated by the US Environmental Protection Agency require that performance assessment calculations for the repository include the possibility that an exploratory drilling operation could penetrate the waste disposal areas at some time in the future. Release of contaminated solids could reach the surface during a drilling intrusion. One of the mechanisms for release, known as spallings, can occur if gas pressures in the repository exceed the hydrostatic pressure of a column of drilling mud. Calculation of solids releases for spallings depends critically on the conceptual models for the waste, for the spallings process, and assumptions regarding driller parameters and practices. The paper presents a review of the evolution of these models during regulatory review of the Compliance Certification Application for the repository. A summary and perspectives on the implementation of conservative assumptions in model development are also provided.
Date: May 22, 2000
Creator: Knowles, M.K; Hansen, F.D.; Thompson, T.W.; Schatz, J.F. & Gross, M.
Partner: UNT Libraries Government Documents Department

Constitutive behavior of reconsolidating crushed salt

Description: The constitutive model used to describe deformation of crushed salt is presented in this paper. Two mechanisms--dislocation creep and grain boundary diffusional pressure solutioning--are combined to form the basis for the constitutive model governing deformation of crushed salt. The constitutive model is generalized to represent three-dimensional states of stress. Recently completed creep consolidation tests are combined with an existing database that includes hydrostatic consolidation and shear consolidation tests conducted on Waste Isolation Pilot Plant (WIPP) and southeastern New Mexico salt to determine material parameters for the constitutive model. Nonlinear least-squares model fitting to data from shear consolidation tests and a combination of shear and hydrostatic tests produces two sets of material parameter values for the model. Changes in material parameter values from test group to test group indicate the empirical nature of the model but show significant improvement over earlier work. To demonstrate the predictive capability of the model, each parameter value set was used to predict each of the tests in the database. Based on fitting statistics and ability of the model to predict test data, the model appears to capture the creep consolidation behavior of crushed salt quite well.
Date: February 1998
Creator: Callahan, G. D.; Mellegard, K. D. & Hansen, F. D.
Partner: UNT Libraries Government Documents Department

Evaluation of potential crushed-salt constitutive models

Description: Constitutive models describing the deformation of crushed salt are presented in this report. Ten constitutive models with potential to describe the phenomenological and micromechanical processes for crushed salt were selected from a literature search. Three of these ten constitutive models, termed Sjaardema-Krieg, Zeuch, and Spiers models, were adopted as candidate constitutive models. The candidate constitutive models were generalized in a consistent manner to three-dimensional states of stress and modified to include the effects of temperature, grain size, and moisture content. A database including hydrostatic consolidation and shear consolidation tests conducted on Waste Isolation Pilot Plant and southeastern New Mexico salt was used to determine material parameters for the candidate constitutive models. Nonlinear least-squares model fitting to data from the hydrostatic consolidation tests, the shear consolidation tests, and a combination of the shear and hydrostatic tests produces three sets of material parameter values for the candidate models. The change in material parameter values from test group to test group indicates the empirical nature of the models. To evaluate the predictive capability of the candidate models, each parameter value set was used to predict each of the tests in the database. Based on the fitting statistics and the ability of the models to predict the test data, the Spiers model appeared to perform slightly better than the other two candidate models. The work reported here is a first-of-its kind evaluation of constitutive models for reconsolidation of crushed salt. Questions remain to be answered. Deficiencies in models and databases are identified and recommendations for future work are made. 85 refs.
Date: December 1, 1995
Creator: Callahan, G.D.; Loken, M.C.; Sambeek, L.L. Van; Chen, R.; Pfeifle, T.W.; Nieland, J.D. et al.
Partner: UNT Libraries Government Documents Department