Kooperativer Bibliotheksverbund

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Format: v, 70 Seiten , Illustrationen

Series Statement: CRREL Report 86-12

Content: Stress-deformation data for six granular soils ranging from sandy silt to dense-graded crushed stone were obtained from in-situ tests and laboratory tests. Surface deflections were measured in the in-situ tests, with repeated-load plate-bearing and falling-weight deflectometer equipment, when the six granular soils were frozen, thawed, and at various stages of recovery from thaw weakening. The measured deflections were used to judge the validity of procedures developed for laboratory triaxial tests to determine nonlinear resilient moduli of specimens in the frozen, thawed, and recovering states. The validity of the nonlinear resilient moduli, expressed as functions of externally applied stress and moisture tension, was confirmed by using the expressions to calculate surface deflections that were found to compare well with deflections measured in the in-situ tests. The tests on specimens at various stages of recovery are especially significant because they show a strong dependence of the resilient modulus on moisture tension, leading to the conclusion that predictions or in-situ measurements of moisture tension can be used to evaluate expected seasonal variation in the resilient modulus of granular soils.

Note: CONTENTS Abstract Preface Introduction Sampling of test section Laboratory tests Asphalt concrete Natural subgrade material Test soils Field tests Analysis of field-loading tests Discussion Conclusions Literature cited Appendix A: Field data Appendix 8: Ground temperatures prevailing during plate-loading tests Appendix C: Measured surface deflections compared with deflections calculated by NELAPAV Appendix D: Resilient moduli and supporting data calculated by NELAPAV

In: CRREL Report, 86-12

Language: English

Keywords: Forschungsbericht

URL: http://hdl.handle.net/11681/9326

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Format: iii, 36 Seiten , Illustrationen

Series Statement: CRREL Report 87-2

Content: This is the third in a series of four reports on the laboratory and field testing of a number of road and airfield subgrades, covering the laboratory repeated-load triaxial testing of five soils in the frozen and thawed states and analysis of the resulting resilient modulus measurements. The laboratory testing procedures allow simulation of the gradual increase in stiffnessfound in frost-susceptible soils after thawing. The resilient modulus is expressed in a nonlinear model in terms of the applied stresses, the soil moisture tension level (for unfrozen soil), the unfrozen water content (for frozen soil) and the dry density. The resilient modulus is about 10 GPa for the frozen material at temperatures in the range of -5° to -8° C. The decrease in modulus with increasing temperature was well-modeled in terms of the unfrozen water content. Upon thaw, the modulus dropped to about 100 MPa and generally increased with increasing confining stress and decreased with increasing principal stress ratio. The modulus also increased with the soil moisture tension level. The resilient Poisson's ratio did not appear to be a systematic function of any of the test variables.

Note: CONTENTS Abstract Preface Introduction Test sections and materials Specimen preparation Test soils Asphalt concrete Laboratory testing Soil testing Waveforms of applied stress Asphalt concrete Data reduction and analysis Soil Asphalt concrete Results and discussion General Resilient modulus Summary Conclusions Literature cited Appendix A: Soil moisture tension versus water content for several test soils Appendix B: Tabulated results for all tests on frozen and thawed soils

In: CRREL Report, 87-2

Language: English

Keywords: Forschungsbericht

URL: https://apps.dtic.mil/dtic/tr/fulltext/u2/a179253.pdf

URL: https://hdl.handle.net/11681/9037

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Format: v, 79 Seiten , Illustrationen

Series Statement: CRREL Report 86-5

Content: This work presents the results of a study to examine the effects of grain size of internal microfractures in polycrystalline ice. Laboratory-prepared specimens were tested under uniaxial, constant-load creep conditions at -5 C. Grain size ranged from 1.5 to 6.0 mm. This range of grain size, under an initial creep stress of 2.0 MPa, led to a significant change in the character of deformation. The finest-grained material displayed no internal cracking and typically experienced strains of 10 to the minus 2nd power at the minimum creep rate epsilon. The coarse-grained material experienced severe cracking and a drop in the strain at epsilon min to approximately 4x10 to the minus 3rd power. Extensive post-test optical analysis allowed estimation of the size distribution and number of microcracks in the tested material. These data led to the development of a relationship between the average crack size and the average grain size. Additionally, the crack size distribution, when normalized to the grain diameter, was very similar for all specimens tested. The results indicate that the average crack size is approximately one-half the average grain diameter over the stated grain size range. A dislocation pileup model is found to adequately predict the onset of internal cracking. The work employed acoustic emission techniques to monitor the fracturing rate occurred. Other topics covered in this report include creep behavior, crack healing, the effect of stress level on fracture size and the orientation of cracked grains. Theoretical aspects of the grain size effect on material behavior are also given.

Note: CONTENTS Abstract Preface Background Present research in perspective Explanations of the grain-size dependency Grain size effects on the ductile to brittle transition Nucleation mechanisms and modeling Characteristic size of nucleated crack Cracking in ice Detection of internal fracturing by acoustic emission techniques Test methods Specimen preparation Creep testing apparatus Crack length and crack density measurements Crack healing measurements Thin section photographs Grain size determination Acquisition of acoustic emission data Presentation of results Specimen characteristics Microcrack measurements Creep behavior Crack healing Slip plane length distribution Acoustic emission observations Grain orientation Analysis and discussion Thick section observations The grain size vs crack size relationship Crack nucleation condition Crack density and specimen strain Creep behavior Normalized crack length Location of cracks Acoustic emission activity Summary and conclusions Suggestions for future work Literature cited Appendix A: Crack length histograms Appendix B: Crystal orientations

In: CRREL Report, 86-5

Language: English

Keywords: Forschungsbericht

URL: https://apps.dtic.mil/docs/citations/ADA171571

URL: https://hdl.handle.net/11681/9321

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Format: vi, 53 Seiten , Illustrationen

Series Statement: CRREL Report 78-23

Note: MAB0014.001: ZSP-201-78/23 , CONTENTS Abstract Preface Nomenclature Conversion factors: Metric (SI) to U.S. customary units of measurement Introduction Selection of experimental approach Previous investigations of effect of freeze-thaw on soil deform ability Selection of laboratory test method Selection of method of field validation tests Field repeated-load plate-bearing tests Test pavements, soils and materials Test procedures and results Resilient modulus of subgrade calculated from field tests Mathematical model Characterization of asphalt concrete Characterization of frozen silt Calculated resilient modulus of silt within the zone of freezing Laboratory repeated-load triaxial tests Specimens, equipment and testing procedures Apparatus Procedures Resilient properties calculated from laboratory tests Calculation methods Asphalt concrete - test results Asphalt concrete - statistical analysis and discussion Silt - test results Silt - statistical analysis Discussion and conclusions Literature cited Appendix A. Repeated-load plate-bearing test results Appendix B. Laboratory repeated-load triaxial test results Appendix C. Regression equation coefficients for resilient modulus and Poisson’s ratio from repeated-load triaxial test data on asphalt concrete and silt Appendix D. Detailed procedures for repeated-load triaxial testing

In: CRREL Report, 78-23

Language: English

Keywords: Forschungsbericht

URL: https://hdl.handle.net/11681/9380

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Format: iv, 15 Seiten , Illustrationen

Series Statement: CRREL Report 82-21

Content: The acoustic emission response from fine-grained polycrystalline ice subjected to constant compressive loads was examined. A number of tests were conducted with the nominal stress ranging from 0.8 to 3.67 MPa at a temperature of -5 C. The acoustic emission response was recorded and the data are presented with respect to time and strain. The source of acoustic emissions in ice is considered in terms of the formation of both microfractures and visible fractures that develop without catastrophic failure of the ice. A model to describe the acoustic emission response is developed.

Note: CONTENTS Abstract Preface Introduction Background Experimental procedures Ice specimens Mechanical test equipment Acoustic emission equipment Data recording Acoustic emission sources in ice Acoustic events and visible fracturing Source mechanisms Tests on ice single crystals General acoustic emission response Analysis of data Transient response Steady-state response Amplitude distribution Combined transient and steady-state response in the time domain Discussion Summary Literature cited

In: CRREL Report, 82-21

Language: English

Keywords: Forschungsbericht

URL: https://hdl.handle.net/11681/9366

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Format: iv, 148 Seiten , Illustrationen

Series Statement: CRREL Report 86-13

Content: Stress-deformation data for six granular soils ranging from sandy silt to dense-graded crushedstone were obtained from in-situ tests and laboratory tests. Surface deflections were measured in the in-situ tests, with repeated-load plate-bearing and falling-weight deflectometer equipment, when the six granular soils were frozen, thawed, and at various stages of recovery from thaw weakening. The measured deflections were used to judge the validity of procedures developed for laboratory triaxial tests to determine nonlinear resilient moduli of specimens in the frozen, thawed, and recovering states. The validity of the nonlinear resilient moduli, expressed as functions of externally applied stress and moisture tension, was confirmed by using the expressions tocalculate surface deflections that were found to compare well with deflections measured in the in-situ tests. The tests on specimens at various stages of recovery are especially significant because they show a strong dependence of the resilient modulus on moisture tension, leading to the conclusion that predictions or in-situ measurements of moisture tension can be used to evaluate expected seasonal variation in the resilient modulus of granular soils.

Note: CONTENTS Abstract Preface Introduction Test sections Installing instruments and sampling Laboratory tests Asphalt concrete Base, subbase and subgrade soils Data analysis for base, subbase and subgrade soils Field tests Analysis of plate loading tests Analytical approach Results Discussion Conclusions Literature cited Appendix A: Field data Appendix B: Ground temperatures, moisture tension, water table and freezing iso-therms prevailing during plate loading tests Appendix C: Measured surface deflections compared with deflections calculated by NELAPAV Appendix D: Resilient moduli and supporting data calculated by NELAPA V at radius 0.0, taxiways A and B.

In: CRREL Report, 86-13

Language: English

Keywords: Forschungsbericht

URL: http://hdl.handle.net/11681/9463

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Format: v, 52 Seiten , Illustrationen

Series Statement: CRREL Report 86-18

Content: Findings from a six-year yield and laboratory program of frost action research in four principal areas are summarized. Research on the first topic, frost susceptibility index tests, led to selection of the Corps of Engineers frost design soil classification system as a useful method at the simplest level of testing. At a much more complex level, a new freezing test combined with a CBR test after thawing is recommended as an index of susceptibility to both frost heave and thaw weakening. Under the second topic, a soil column and dual gamma system were developed and applied to obtain soil data used in improving and validating a mathematical model of frost heave, the objective of the third research topic. The model was effectively improved, a probabilistic component was added, and it was successfully tested against field and laboratory measurements of frost heave. A thaw consolidation algorithm was added, which was shown to be useful in predicting the seasonal variation in resilient modulus of granular soils, the objective of the fourth topic. A laboratory testing procedure was developed for assessing the resilient modulus of thawed soil at various stages of the recovery process, as a function of the applied stress and the soil moisture tension, which increases as the soil gradually desaturates during recovery. The procedure was validated by means of appropriate analyses of deflections measured on pavements by a falling-weight deflectometer. Frameworks for implementing findings from the principal research topics are outlined. Keywords: Airfields, Freezing thawing, Frost heave, Frozen soil, Resilient modulus, Roads.

Note: Contents Abstract Preface Introduction Field test sites Frost-susceptibility index testing Index tests selected Laboratory test results Conclusions Soil column and dual gamma system Design features Test results Mathematical model of frost heave and thaw settlement Model development Numerical approach Probabilistic concepts Model verification Discussion Seasonal variation in the resilient modulus of granular soils Characterization by laboratory testing Field verification Summary of predictive approach Simulating frost heave and pavement deflection Method of evaluation Results and discussion Summary of findings Frost-susceptibility index tests Soil column and dual gamma system Mathematical model of frost heave and thaw settlement Seasonal variation in resilient modulus of granular soils Implementation of research findings Corps of engineers frost design soil classification system New laboratory freeze-thaw test Frost-heave model Repeated-load triaxial test on frozen and thawed soil Evaluation of seasonal variation of resilient modulus Literature cited

In: CRREL Report, 86-18

Language: English

Keywords: Forschungsbericht

URL: https://apps.dtic.mil/docs/citations/ADA178243

URL: https://hdl.handle.net/11681/9457

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Format: XV, 384 S , zahlr. Ill , 29 cm

ISBN: 9780300181142

Content: Introduction / by Bruce Barnes -- Life and work / Deborah Dependahl Waters and Bruce Barnes. Becoming an artist -- Setting up shop -- Making her name -- Weathering the storm -- Hunting and fishing -- In context / by Joseph Cunningham. Jewelry -- Tabletop objects -- Silver and gold -- Iron and bronze -- Color as ornament

Note: Includes bibliographical references and index , Introduction , Life and work , Setting up shop ; Making her name ; Weathering the storm ; Hunting and fishing ; In context , Tabletop objects ; Silver and gold ; Iron and bronze ; Color as ornament.

Language: English

Keywords: Zimmermann, Marie 1879-1972 ; Schmuck ; Kunsthandwerk ; Metallkunst

URL: Inhaltsverzeichnis

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Format: 1 online resource (304 p.)

ISBN: 9781845459079

Series Statement: Environmental Anthropology and Ethnobiology ; 11

Content: Contrary to ingrained academic and public assumptions, wherein indigenous lowland South American societies are viewed as the product of historical emplacement and spatial stasis, there is widespread evidence to suggest that migration and displacement have been the norm, and not the exception. This original and thought-provoking collection of case studies examines some of the ways in which migration, and the concomitant processes of ecological and social change, have shaped and continue to shape human-environment relations in Amazonia. Drawing on a wide range of historical time frames (from pre-conquest times to the present) and ethnographic contexts, different chapters examine the complex and important links between migration and the classification, management, and domestication of plants and landscapes, as well as the incorporation and transformation of environmental knowledge, practices, ideologies and identities.

Note: Frontmatter -- , Contents -- , List of Figures and Tables -- , List of Contributors -- , Editor’s Preface -- , CHAPTER 1 Mobility and Migration in Indigenous Amazonia: Contemporary Ethnoecological Perspectives – an Introduction -- , PART I CIRCULATIONS: MOBILITY, SUBSISTENCE AND THE ENVIRONMENT -- , CHAPTER 2 Towards an Understanding of the Huaorani Ways of Knowing and Naming Plants -- , CHAPTER 3 The Restless Life of the Nahua: Shaping People and Places in the Peruvian Amazon -- , CHAPTER 4 Urban, Rural and In-between: Multi-sited Households Mobility and Resource Management in the Amazon Flood Plain -- , CHAPTER 5 Unpicking ‘Community’ in Community Conservation: Implications of Changing Settlement Patterns and Individual Mobility for the Tamshiyacu Tahuayo Communal Reserve, Peru -- , PART II TRANSFORMATIONS: KNOWLEDGE, IDENTITY, PLACE-MAKING AND THE DOMESTICATION OF NATURE -- , CHAPTER 6 Domestication of Peach Palm (Bactris gasipaes): the Roles of Human Mobility and Migration -- , CHAPTER 7 Intermediation, Ethnogenesis and Landscape Transformation at the Intersection of the Andes and the Amazon: the Historical Ecology of the Lecos of Apolo, Bolivia -- , CHAPTER 8 The Political Ecology of Ethnic Frontiers and Relations among the Piaroa of the Middle Orinoco -- , CHAPTER 9 ‘Ordenar El Pensamiento’: Place-Making and the Moral Management of Resources in a Multi- Ethnic Territory, Amazonas, Colombia -- , CHAPTER 10 Plants ‘of the Ancestors’, Plants ‘of the Outsiders’: Ese Eja History, Migration and Medicinal Plants -- , CHAPTER 11 Weaving Power: Displacement and the Dynamics of Basketry Knowledge amongst the Kaiabi in the Brazilian Amazon -- , CHAPTER 12 Traditions in Transition: African Diaspora Ethnobotany in Lowland South America -- , Index , In English.

Language: English

DOI: 10.1515/9781845459079

URL: https://doi.org/10.1515/9781845459079

URL: https://www.degruyter.com/isbn/9781845459079

URL: https://doi.org/10.1515/9781845459079

URL: https://www.degruyter.com/isbn/9781845459079