Download or read book Effect of Fabric and Weathering Intensity on Dynamic Properties of Residual and Saprolitic Soils Via Resonant Column Testing written by Jorge A. Pineda and published by . This book was released on 2014 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical weathering processes, such as decomposition and dissolution, are fairly well-understood phenomena as they relate to the formation of residual and saprolitic soils in the tropics. However, the effects that weathering intensity has on the physical characteristics and mechanical properties of weathered soil/rock materials, particularly their dynamic properties, are not yet fully understood. This paper presents the results of an experimental investigation conducted to assess the dynamic response of residual and saprolitic soils derived from a granodiorite rock in the central mountain range of Colombia and how this response relates to the soil microstructure and weathering intensity. Key dynamic properties, namely, shear modulus and material damping, were obtained via a fixed-free resonant column apparatus suitable for shear strain amplitudes ranging from 0.001 % to 0.1 %. Results from a short series of triaxial and oedometer tests substantiated the patterns of weathering intensity observed for each test soil. Soil fabric studies based on scanning electron microscopy observations, mercury intrusion porosimetry tests, and pore space distributions were also performed to identify the most relevant characteristics of the soil skeleton, as determined by the corresponding weathering intensity, that affect the dynamic response of each test soil. The residual soil, as the most altered/weathered material, was found to have a more rigid fabric, and thus greater stiffness, due to the presence of sesquioxides acting as cementing agents. In the saprolitic soil, a less weathered material, the soil fabric was dominated by distinct clay bridges formed between particle aggregations of partially decomposed primary minerals, resulting in less rigidity. The influence of confinement level on the shear modulus was found to be more pronounced in the saprolitic soil, which can be directly attributed to the changes in fabric of uncemented bonds during isotropic loading. Finally, and consistent with these general trends, the material damping of saprolitic soil was observed to be slightly less than that of residual soil, whereas the normalized shear moduli (G/Gmax) degradation curve was more pronounced in residual soil samples beyond a threshold value of shear strain amplitude.
Download or read book Earthquake Geotechnical Engineering for Protection and Development of Environment and Constructions written by Francesco Silvestri and published by CRC Press. This book was released on 2019-07-19 with total page 8083 pages. Available in PDF, EPUB and Kindle. Book excerpt: Earthquake Geotechnical Engineering for Protection and Development of Environment and Constructions contains invited, keynote and theme lectures and regular papers presented at the 7th International Conference on Earthquake Geotechnical Engineering (Rome, Italy, 17-20 June 2019. The contributions deal with recent developments and advancements as well as case histories, field monitoring, experimental characterization, physical and analytical modelling, and applications related to the variety of environmental phenomena induced by earthquakes in soils and their effects on engineered systems interacting with them. The book is divided in the sections below: Invited papers Keynote papers Theme lectures Special Session on Large Scale Testing Special Session on Liquefact Projects Special Session on Lessons learned from recent earthquakes Special Session on the Central Italy earthquake Regular papers Earthquake Geotechnical Engineering for Protection and Development of Environment and Constructions provides a significant up-to-date collection of recent experiences and developments, and aims at engineers, geologists and seismologists, consultants, public and private contractors, local national and international authorities, and to all those involved in research and practice related to Earthquake Geotechnical Engineering.
Download or read book Geotechnical Aspects of Underground Construction in Soft Ground written by Arsenio Negro and published by CRC Press. This book was released on 2017-11-23 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: Geotechnical Aspects of Underground Construction in Soft Ground comprises the second Fujita lecture, three keynote lectures and the regular papers presented at the Ninth International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground (IS - Sao Paulo 2017, Sao Paulo, Brazil, 4-6 April 2017). The Symposium was organized by the Brazilian Tunnelling Committee (CBT) of the Brazilian Geotechnical Society (ABMS), under the auspices of the Technical Committee TC204 of the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE). The contributions cover a wide range of topics: - Deep Excavations - Interaction with Adjacent Structures - Mechanized Excavations - Sequential Excavations - Physical Modelling and Field Tests - Case Histories Geotechnical Aspects of Underground Construction in Soft Ground is particularly aimed at academics and professionals interested or involved in geotechnical and underground engineering. Similarly to previous editions, the contributions are a valuable source of reference on the current practice on the analysis, design and construction of tunnels, deep excavations and large underground structures, with particular emphasis on the development, effects and control of ground movements, their interaction with existing structures, mitigation measures and risk management. IS - Sao Paulo 2017 is the latest in a series of ISSMGE’s TC204 symposia, which began in New Delhi (1993), followed by symposia in London (1996), Tokyo (1999), Toulouse (2002), Amsterdam (2005), Shanghai (2008), Rome (2011) and Seoul (2014).
Download or read book Effect of Loading Frequency on Dynamic Properties of Soils Using Resonant Column written by Soheil Moayerian and published by . This book was released on 2012 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamic properties of soils (shear stiffness and damping ratio) are critical for the design of structures subjected to vibrations. The dynamic properties of a benchmark standardized laboratory sand (Ottawa silica sand) were evaluated with two different resonant column devices, utilising software with different analytical approaches for the evaluation of soil properties. The dynamic properties (shear modulus and damping ratio) are evaluated as a function of the shear strain level. The results are compared to evaluate the effect of the type of equipment and the form of the data analysis on the measured dynamic properties of the samples. The results are discussed in light of the applicability of the procedures in practice, the ease of the testing methods, and the errors they introduced into analysis and design. In general, the shear wave velocities obtained from the two different devices are in good agreement. However, the damping ratios they give show considerable differences as strains increase. Dynamic properties are typically measured by curve fitting of the transfer function between the excitation and the response using the resonant column device. However, the force function generated by sinusoidal sweep or random noise excitations induce different shear strain levels at different frequencies. Consequently, the shape of the measured transfer function is distorted and differs from the theoretical transfer function for an equivalent single-degree-of-freedom system. The difference between the measured and theoretical transfer functions as well as the bias in the computed dynamic properties becomes more pronounced with the increase in shear strain. This study presents a new methodology for the evaluation of dynamic properties from an equivalent constant-strain transfer function. The soil specimen is excited simultaneously using a sinusoidal excitation (carrier signal) at the required strain level and a small amplitude, narrow band random noise. The strain level induced by the fixed sine is shown to control the resonant frequency of the specimen; whereas the random noise introduces the required frequency bandwidth to determine the transfer function and hence the dynamic properties at a constant strain level. The new methodology also shows a good potential for the evaluation of frequency effects on the dynamic properties of soils in resonant column testing.
Download or read book Dynamic Properties of Stabilized Soils written by Mehmet Erdem Ardaman and published by . This book was released on 1955 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evaluation of Dynamic Soil Properties written by Dugkeun Park and published by . This book was released on 1998 with total page 1168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanics of Residual Soils written by Geoffrey E. Blight and published by Taylor & Francis. This book was released on 2012-05-03 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: Residual soils are found in many parts of the world and are used extensively as construction materials for roads, embankments and dams, and to support the foundations of buildings, bridges and load-bearing pavements. The characteristics and engineering properties of residual soils can differ significantly from those of the more familiar transported
Download or read book Stiffness Response of Chemically Stabilized Sulfate Rich Soil Via Resonant Column Testing written by Miftah Semane and published by . This book was released on 2014 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stabilization of expansive soils using lime and cement additives have been used by practitioners over the last few years. However, recent heaving and premature pavement failures in lime and cement-treated subgrades containing sulfates led to questioning the validity of calcium based stabilization. When expansive soils containing sulfates are treated with calcium-based stabilizers, the calcium from the stabilizer reacts with soil sulfates and alumina to form the expansive mineral Ettringite. A series of resonant column (RC) tests (ASTM D 4015-92) was conducted on several chemically stabilized specimens of high-plasticity, sulfate-rich expansive clay from Sherman, Texas. Test results were used to assess the influence of mellowing period on the stiffness properties of stabilized soil. Specimens were tested for different stabilizer, mellowing periods, curing times, and confining pressures, and elapsed times under constant confinement. Two stabilizers, 6% lime and 4% lime + 8% fly ash, were used. Soil stiffness parameters investigated include small-strain shear modulus (G) and small-strain material damping ratio (D). Tests were also conducted at mid- to high-strain levels to study stiffness degradation effects of torsional shearing. 4% lime + 8% fly ash treatment method shows the best results.
Download or read book An Experimental Study of the Dynamic Behavior of Soils written by Gwo-fea Luh and published by . This book was released on 1980 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Non Resonance Method for Measuring Dynamic Soil Properties written by GJ. Rix and published by . This book was released on 2005 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: A non-resonance (NR) test method is introduced to determine dynamic soil properties at low strain amplitudes over a broad frequency range using a conventional resonant column/torsional shear (RC/TS) apparatus. The theoretical background of the NR method is presented and it is shown that the shear modulus and material damping ratio can be obtained from frequency response measurements between the applied torque and resulting rotational displacement of the specimen. By properly accounting for inertia effects, the NR method allows measurements at frequencies (e.g., 2-30 Hz) that fill the gap between conventional RC and TS tests. Experimental results are presented for aluminum alloy, polymethyl methacrylate (PMMA), and soil specimens over the frequency range of 0.01-30 Hz. Values for aluminum alloy and PMMA, used as calibration materials, obtained with the NR method agree well with reference values from the literature and help validate the approach. Tests on two soil specimens indicate that the NR method permits continuous measurements of shear modulus and material damping ratio of soils over a broad frequency range, which has the potential to yield improved understanding of viscoelastic soil behavior and provide dynamic soil properties over a range of frequencies appropriate for a variety of natural and man-made vibration sources.
Download or read book Experimental Investigations on Small strain Stiffness Properties of Partially Saturated Soils Via Resonant Column and Bender Element Testing written by Phayak Takkabutr and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive series of resonant column (ASTM D 2325-68), bender element (ASTM C 778), pressure plate (ASTM D 4015-92), and filter paper (ASTM D 5298) tests were conducted on compacted specimens of poorly graded sand (SP) and high plasticity clay (CH) in order to assess the influence of key environmental factors, namely compaction-induced matric suction and Ko stress state, on small-strain stiffness properties of partially saturated soils. Compaction-induced matric suction in all test specimens was estimated via soil-water characteristic curves (SWCC) for each type of soil. The research work was accomplished in six broad stages. During Stage I, a modified pressure plate extractor device was developed for assessing SWCC under anisotropic stress sates. Results from a series of SWCC tests on SP and CH specimens were used to assess the Fredlund and Xing's SWCC model parameters for each type of soil. During Stage II, resonant column (RC) tests were conducted on SP and CH specimens, at different compaction-induced suctions and isotropic confinements, in order to devise correlations between small-strain stiffness properties, i.e. shear modulus (Gmax) and material damping (D min), and matric suction (Psi). During Stage III, bender element (BE) tests were conducted on SP and CH specimens for the same experimental variables as in Stage II. Results were used to investigate the influence of suction on bender element performance as compared to resonant column testing. During Stage IV, bender element (BE) tests were conducted on SP and CH specimens at different compaction-induced suctions and K o stress states. Results were used to devise a correction factor for RC results, on the basis of initial compaction-induced suction, for any given Ko stress condition. During Stage V, a series of RC and BE tests were conducted on SP and CH specimens using a resonant column device with self-contained bender elements. Results were used to further substantiate the experimental findings and correlations devised in Stages II, III and IV. Finally, during Stage VI, bender element tests were conducted on SP and CH specimens sheared at different vertical strain levels in order to assess the influence of vertical strain level on suction loss and menisci regeneration patterns.
Download or read book Laboratory Investigation of the Stiffness and Damping Properties of Binary and Gap graded Mixtures of Granular Soils written by Boonam Shin and published by . This book was released on 2018 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sandy and gravelly soils are encountered in many natural soil strata such as alluvial, fluvial, residual, and glacial deposits. These granular materials are used in the construction of many types of man-made geotechnical structures, fills, and ground improvements. A need exists to understand the dynamic behavior of these sandy and gravelly mixtures. A “binary packing model” has been proposed by some researchers to represent a simplified model for some sandy and gravelly soils that are composed of only a few, quite different, particle sizes (typically more than a factor of 20, and a factor of 34 used in this study) created during construction of geotechnical systems or in the natural environment. In other cases, gap-graded materials have been created. The packing condition and void distribution in the two types of gradations are complicated due to large variations in particle size and construction conditions. Up to now, no systematic studies have been conducted to evaluate key factors in the soil matrix (i.e., the parent materials in these mixtures) affecting the dynamic properties (i.e., shear modulus, G, and material damping ratio, D) of the binary and gap-graded mixtures considering the packing state of the matrix particles. In binary granular soils, estimating the critical packing condition, which represents the case when all void space between the large particles are completely filled with each group of small particles, is important. Additionally, the associated critical small-particle content (SPC*), which is the small-particle content (SPC) under the critical packing condition, can be calculated using the void ratios of the small-particle and large-particle materials. In this research, systematic variations of the parent materials in binary and gap-graded mixtures (i.e., the small and large particles in binary mixtures) were created, and the dynamic torsional resonant column (RC) testing was performed on a wide range of particle packing conditions. Some findings are: 1) the binary and gap-graded specimens for SPC ≥ 76% behaved very similarly to their parent poorly graded sand in both the small-strain and nonlinear dynamic properties; 2) the binary specimens for 15% ≤ SPC ≤ 100% showed a clear trend in the relationship of small-strain shear modulus at one atmosphere (A [subscript G]) and void ratio (e); 3) the binary specimens for 23% ≤ SPC ≤ 36%, which were in the range of SPC*, showed the highest stiffnesses and most nonlinearity; and 4) overall, the void ratio was a better parameter than the uniformity coefficient to estimate the nonlinear behavior of the specimens for 0% ≤ SPC ≤ 39%
Download or read book Dynamic Soil Testing with Resonant Column Method written by and published by . This book was released on 1984 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Loading Type on the Dynamic Properties of Soils written by Mohd. Raihan Taha and published by . This book was released on 1987 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laboratory Evaluation of Dynamic Soil Properties by Ultrasonic Testing Methods written by Ronald Maurice Eckelkamp and published by . This book was released on 1974 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book In Situ Testing in Geomechanics written by Fernando Schnaid and published by CRC Press. This book was released on 2009-01-13 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: Demanding a thorough knowledge of material behaviour and numerical modelling, site characterisation and in situ test interpretation are no longer just basic empirical recommendations. Giving a critical appraisal of the understanding and assessment of the stress-strain-time and strength characteristics of geomaterials, this book explores new interpretation methods for measuring properties of a variety of soil formations. Emphasis is given to the five most commonly encountered in situ test techniques: standard penetration tests cone penetration tests vane test pressuremeter tests dilatometer tests Ideal for practising engineers in the fields of geomechanics and environmental engineering, this book solves numerous common problems in site characterisation. It is also a valuable companion for students coming to the end of their engineering courses and looking to work in this sector.
Download or read book The Origin of Clay Minerals in Soils and Weathered Rocks written by Bruce B. Velde and published by Springer Science & Business Media. This book was released on 2008-07-18 with total page 407 pages. Available in PDF, EPUB and Kindle. Book excerpt: Of huge relevance in a number of fields, this is a survey of the different processes of soil clay mineral formation and the consequences of these processes concerning the soil ecosystem, especially plant and mineral. Two independent systems form soil materials. The first is the interaction of rocks and water, unstable minerals adjusting to surface conditions. The second is the interaction of the biosphere with clays in the upper parts of alteration profiles.
