Download or read book Study of drying wetting effects ou the shear strength of a soil compacted in laboratory written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: No presente trabalho, pretende-se avaliar os efeitos de ciclos de umedecimento e secagem na resistência ao cisalhamento do solo. Este estudo é de grande importância, particularmente, para os solos brasileiros, já que se encontram em uma região tropical, onde verifica-se aocorrência de períodos bem definidos de chuvas e estiagem. Sabe-se que, longos períodos de chuvas podem saturar o solo, assim como durante a estiagem, pode ocorrer uma maior evaporação do que infiltração de água, o que leva o solo a uma condição não saturada, provocando o surgimento de uma nova componente de resistência, a coesão aparente. Na natureza, estes dois períodos não ocorrem de maneira uniforme, fazendo com que o solo atinja valores de sucção diferentes, dependendo do seu umedecimento esecagem. Assim sendo, ciclos de umedecimento e secagem e o nível de sucção atingido correspondente, podem afetar o comportamento mecânico do solo. Afim de verificar a influência de tais ciclos de umedecimento e secagem, determinou-se a resistência ao cisalhamento do solo, por meio de ensaios de cisalhamento direto com sucçãocontrolada no equipamento desenvolvido na PUC-Rio. O umedecimento e a secagem do solo, foram simulados, em laboratório, através da diminuição e aumento da sucção, respectivamente. Utilizou-se o solo maduro do campo experimental II da PUC-Rio, peneirado e compactado em laboratório. Foram realizadas várias séries de ensaios, em que se modificavam os procedimentos realizados em relação aos níveis de sucção aplicados. A partir dos resultados obtidos, verificou-se a influência dos ciclos de umedecimento e secagem e dos níveis de sucçãoatingidos em cada caso, na resistência ao cisalhamento do solo, bem como na variação de volume total e de água nas amostras, durante o cisalhamento.
Download or read book The effects of wetting and drying on the long term shear strength parameters for compacted Beaumont clay written by and published by . This book was released on 1986 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The effects of wetting and drying on the long term shear strength of compacted Beaumont clay written by Laura Elaine Rogers and published by . This book was released on 1986 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Glissement de Terrain Evaluation Et Stabilisation written by Willy Alvarenga Lacerda and published by Taylor & Francis US. This book was released on 2004 with total page 1810 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effect of Drying and Wetting on the Shear Strength of a Low Plasticity Clay With Different Initial Dry Densities written by Wenhua Liu and published by . This book was released on 2015 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soils near the ground surface are naturally subjected to drying and wetting cycles because of climatic changes. The shear strength variations of soils induced by drying and wetting affect the stability of the geotechnical structures. The general objective of this study is to assess the effect of drying and wetting on the shear strength of a low-plasticity clay, classified as CL according to the Unified Soil Classification System, from Dalian, China. A series of consolidated undrained triaxial tests were conducted on the specimens with three different initial dry densities of 1.61, 1.71, and 1.76 Mg/m3. These tests were conducted under the saturated condition after the specimens were subjected to different numbers of drying and wetting cycles. The results indicate that drying and wetting have different impacts on the mechanical behaviors of soils with different initial dry densities. For the specimens with the initial dry density of 1.61 Mg/m3, the internal friction angle increased, whereas the residual strength and cohesion decreased after cyclic drying and wetting. The stress-strain relationships altered from strain hardening to strain softening. As for the specimens with the initial dry density of 1.71 and 1.76 Mg/m3, the internal friction angle, residual strength, and cohesion all decreased after cyclic drying and wetting. Based on the experimental results, it is concluded that the variations of the shear strengths can be attributed to the irreversible volume compression and the variation of dilatancy. The overall influence of drying and wetting on the mechanical behaviors depends on the initial state of soils.
Download or read book Laboratory Shear Strength of Soil written by Raymond Nen Yong and published by ASTM International. This book was released on 1981 with total page 736 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Landslides Evaluation and Stabilization Glissement de Terrain Evaluation et Stabilisation Set of 2 Volumes written by W. Lacerda and published by CRC Press. This book was released on 2004-06-15 with total page 1772 pages. Available in PDF, EPUB and Kindle. Book excerpt: These volumes comprise the Proceedings of the Ninth International Symposium on Landslides, held in Rio de Janeiro, Brazil, from June 28 to July 2, 2004. Information on the latest developments in Landslide Studies is presented by invited lecture reports, specialized panel contributions and over two hundred and forty technical papers, grouped in the following themes: - Mapping and geological models in landslide hazard assessment, - Advances in rock and mine slopes design, - Field instrumentation and laboratory investigations, - Pre-failure mechanics of landslides in soil and rock, - Mechanisms of slow active landslides, - Post-failure mechanics of landslides, - Stabilization methods and risk reduction measures. A wealth of the latest information on all aspects of landslide hazard, encompassing geological modelling and soil and rock mechanics, landslide processes, causes and effects, and damage avoidance and limitation strategies.
Download or read book Laboratory Shear Strength of Soil written by Ramond Nen Yong and published by ASTM International. This book was released on 1981 with total page 721 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the 16th International Conference on Soil Mechanics and Geotechnical Engineering written by The Organizing Committee of the 16th ICSMGE and published by IOS Press. This book was released on 2005-09-12 with total page 3742 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 16th ICSMGE responds to the needs of the engineering and construction community, promoting dialog and exchange between academia and practice in various aspects of soil mechanics and geotechnical engineering. This is reflected in the central theme of the conference 'Geotechnology in Harmony with the Global Environment'. The proceedings of the conference are of great interest for geo-engineers and researchers in soil mechanics and geotechnical engineering. Volume 1 contains 5 plenary session lectures, the Terzaghi Oration, Heritage Lecture, and 3 papers presented in the major project session. Volumes 2, 3, and 4 contain papers with the following topics: Soil mechanics in general; Infrastructure and mobility; Environmental issues of geotechnical engineering; Enhancing natural disaster reduction systems; Professional practice and education. Volume 5 contains the report of practitioner/academic forum, 20 general reports, a summary of the sessions and workshops held during the conference.
Download or read book Volume Change Behavior of Expansive Soils Due to Wetting and Drying Cycles written by Daniel Curtis Rosenbalm and published by . This book was released on 2013 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a laboratory setting, the soil volume change behavior is best represented by using various testing standards on undisturbed or remolded samples. Whenever possible, it is most precise to use undisturbed samples to assess the volume change behavior but in the absence of undisturbed specimens, remodeled samples can be used. If that is the case, the soil is compacted to in-situ density and water content (or matric suction), which should best represent the expansive profile in question. It is standard practice to subject the specimen to a wetting process at a particular net normal stress. Even though currently accepted laboratory testing standard procedures provide insight on how the profile conditions changes with time, these procedures do not assess the long term effects on the soil due to climatic changes. In this experimental study, an assessment and quantification of the effect of multiple wetting/drying cycles on the volume change behavior of two different naturally occurring soils was performed. The changes in wetting and drying cycles were extreme when comparing the swings in matric suction. During the drying cycle, the expansive soil was subjected to extreme conditions, which decreased the moisture content less than the shrinkage limit. Nevertheless, both soils were remolded at five different compacted conditions and loaded to five different net normal stresses. Each sample was subjected to six wetting and drying cycles. During the assessment, it was evident from the results that the swell/collapse strain is highly non-linear at low stress levels. The strain-net normal stress relationship cannot be defined by one single function without transforming the data. Therefore, the dataset needs to be fitted to a bi-modal logarithmic function or to a logarithmic transformation of net normal stress in order to use a third order polynomial fit. It was also determined that the moisture content changes with time are best fit by non-linear functions. For the drying cycle, the radial strain was determined to have a constant rate of change with respect to the axial strain. However, for the wetting cycle, there was not enough radial strain data to develop correlations and therefore, an assumption was made based on 55 different test measurements/observations, for the wetting cycles. In general, it was observed that after each subsequent cycle, higher swelling was exhibited for lower net normal stress values; while higher collapse potential was observed for higher net normal stress values, once the net normal stress was less than/greater than a threshold net normal stress value. Furthermore, the swelling pressure underwent a reduction in all cases. Particularly, the Anthem soil exhibited a reduction in swelling pressure by at least 20 percent after the first wetting/drying cycle; while Colorado soil exhibited a reduction of 50 percent. After about the fourth cycle, the swelling pressure seemed to stabilized to an equilibrium value at which a reduction of 46 percent was observed for the Anthem soil and 68 percent reduction for the Colorado soil. The impact of the initial compacted conditions on heave characteristics was studied. Results indicated that materials compacted at higher densities exhibited greater swell potential. When comparing specimens compacted at the same density but at different moisture content (matric suction), it was observed that specimens compacted at higher suction would exhibit higher swelling potential, when subjected to the same net normal stress. The least amount of swelling strain was observed on specimens compacted at the lowest dry density and the lowest matric suction (higher water content). The results from the laboratory testing were used to develop ultimate heave profiles for both soils. This analysis showed that even though the swell pressure for each soil decreased with cycles, the amount of heave would increase or decrease depending upon the initial compaction condition. When the specimen was compacted at 110% of optimum moisture content and 90% of maximum dry density, it resulted in an ultimate heave reduction of 92 percent for Anthem and 685 percent for Colorado soil. On the other hand, when the soils were compacted at 90% optimum moisture content and 100% of the maximum dry density, Anthem specimens heave 78% more and Colorado specimens heave was reduced by 69%. Based on the results obtained, it is evident that the current methods to estimate heave and swelling pressure do not consider the effect of wetting/drying cycles; and seem to fail capturing the free swell potential of the soil. Recommendations for improvement current methods of practice are provided.
Download or read book The Recovery of Soils After Compaction A Laboratory Investigation Into the Effect of Wet dry Cycles on Bulk Density and Soil Hydraulic Functions written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Van den Akker et al. (2003) stated that "European subsoils are more threatened than ever in history" in an editorial referring to the results of the European Union concerted action "Experiences with the impact of subsoil compaction on soil crop growth and environment and ways to prevent subsoil compaction". Compaction of agricultural soils not only reduces yields but can lead to pollution of surface waters and the release of greenhouse gases. Understanding, therefore, how, and to what extent, subsoil compaction may be reversed seems of vital importance. The literature suggests that soils with a range of textures could recover structural properties such as total and macro-porosity, infiltration rate and stability, although the extent and depth of these changes varies greatly. Factors affecting the extent and depth of changes are the rate of wetting and drying and the matric potentials achieved during drying (influenced by crop cover and irrigation practices as well as climate), organic matter content and tillage history. There is, however, a limited amount of information regarding changes to the pore-size distribution and unsaturated hydraulic conductivity of soils with wet/dry cycles. Although there are models able to predict the compaction that would occur for a given set of conditions, as well as the compactibility of soils and surface crack generation, there are no predictive models that describe structural changes due to wet/dry cycles. The aims of this study were to assess the changes in bulk density and hydrological parameters of a range of soils, of varying texture and other physical and chemical properties, with wet/dry cycles and to explore the relationships between any measured changes and the measured soil properties. A series of laboratory experiments were designed to measure changes to the total porosity and pore size distribution and hydraulic functions of soil samples. Changes to bulk density and moisture content of undisturbed soil cores at field cap.
Download or read book Advanced Experimental Unsaturated Soil Mechanics written by Alessandro Tarantino and published by CRC Press. This book was released on 2005-07-14 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of experimental unsaturated soil mechanics has grown considerably over the last decade. In the laboratory and in the field, innovative techniques have been introduced into mechanical, hydraulic, and geo-environmental testing. Normally, this information is widely dispersed throughout journals and conference proceedings and it is often difficult to identify suitable equipment and instrumentation for research or professional purposes. In this volume, however, the authors bring together the latest research in laboratory and field testing techniques, and the equipment employed, and examine the current state-of-the-art in a forum devoted solely to experimental unsaturated soil mechanics. The papers published in the proceedings were peer-reviewed by internationally-recognized researchers. The topics tackled by the papers include suction measurement, suction control, mechanical and hydraulic laboratory testing, geo-environmental testing, and field-testing.
Download or read book HRIS Abstracts written by and published by . This book was released on 1988 with total page 956 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Encyclopedia of Agrophysics written by Jan Gliński and published by Springer Science & Business Media. This book was released on 2011-06-07 with total page 1075 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Encyclopedia of Agrophysics will provide up-to-date information on the physical properties and processes affecting the quality of the environment and plant production. It will be a "first-up" volume which will nicely complement the recently published Encyclopedia of Soil Science, (November 2007) which was published in the same series. In a single authoritative volume a collection of about 250 informative articles and ca 400 glossary terms covering all aspects of agrophysics will be presented. The authors will be renowned specialists in various aspects in agrophysics from a wide variety of countries. Agrophysics is important both for research and practical use not only in agriculture, but also in areas like environmental science, land reclamation, food processing etc. Agrophysics is a relatively new interdisciplinary field closely related to Agrochemistry, Agrobiology, Agroclimatology and Agroecology. Nowadays it has been fully accepted as an agricultural and environmental discipline. As such this Encyclopedia volume will be an indispensable working tool for scientists and practitioners from different disciplines, like agriculture, soil science, geosciences, environmental science, geography, and engineering.
Download or read book Landslide Hazards in Alpine Region Mechanics and Mitigation written by Yun Zheng and published by Frontiers Media SA. This book was released on 2022-11-01 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research Conference on Shear Strength of Cohesive Soils Sponsored by the Soil Mechanics and Foundations Division ASCE Papers and Reports written by and published by . This book was released on 1961 with total page 1190 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Soil Survey of Chilton County Alabama written by Robert Britton McNutt and published by . This book was released on 1972 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
