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 The Combined Effects of Loading Frequency and Other Parameters on Dynamic Properties of Reconstituted Cohesive Soils written by Wiliam Browne Gookin and published by . This book was released on 1998 with total page 836 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 Soil Dynamics and Foundation Modeling written by Junbo Jia and published by Springer. This book was released on 2017-11-26 with total page 741 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a comprehensive topical overview on soil dynamics and foundation modeling in offshore and earthquake engineering. The spectrum of topics include, but is not limited to, soil behavior, soil dynamics, earthquake site response analysis, soil liquefactions, as well as the modeling and assessment of shallow and deep foundations. The author provides the reader with both theory and practical applications, and thoroughly links the methodological approaches with engineering applications. The book also contains cutting-edge developments in offshore foundation engineering such as anchor piles, suction piles, pile torsion modeling, soil ageing effects and scour estimation. The target audience primarily comprises research experts and practitioners in the field of offshore engineering, but the book may also be beneficial for graduate students.

Download or read book Dynamic Properties of Soils with Non plastic Fines written by David Umberg and published by . This book was released on 2012 with total page 792 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results from an experimental study on the dynamic properties of sand with nonplastic silt are presented. Combined resonant column and torsional shear equipment is used to evaluate the effects of confining pressure, shearing strain, frequency, and number of cycles of loading on the dynamic properties of silty sand. The goal of this study is to determine if relationships in the literature for sands and gravels are accurate for predicting the shear modulus and material damping characteristics of soil with nonplastic fines or if the incorporation of a fines content parameter improves predictions. This goal was primarily accomplished by reconstituting and testing samples of an alluvial deposit from Dillon Dam, Dillon, Colorado according to predetermined gradation curves with variable amounts of non-plastic fines. Among the findings of this investigation are: (1) soil parameters such as Cu and D50 can be related to dynamic properties of soils with up to 25% fines, (2) the effects of non-plastic fines on the small-strain dynamic properties of soils are not very pronounced for soils with less than 25% fines, and (3) an increase in the amount of non-plastic fines in uniform soils or soils with more than 25% fines generally results in lower values of small-strain shear modulus, higher values of small-strain material damping, and more linear G/Gmax - log([gamma]) and D - log([gamma]) curves. The effect of non-contacting, larger granular particles in a finer soil matrix is also investigated along with the impact of removing larger particles from laboratory samples.

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 Study of Laboratory and Field Techniques to Measure Shear Wave Parameters Frequency Effects written by Hassan Ali and published by . This book was released on 2015 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last decade, significance of correctly evaluating the dynamic properties of soil has been widely recognized by the research community. Among various parameters, shear wave velocity and damping ratio has been recognized as the key parameter for the soils subjected to dynamic loading. The shear wave velocity is used in the geotechnical assessments for site characterization, ground response analysis, and liquefaction potential. The dynamic properties of the soils can be attained in the lab or in-situ. The dynamic soil properties are dependent on different state parameters, such as, void ratio, confining stress, water content, strain levels, and drainage conditions. Apart from the influence of the above parameters, the dynamic soil parameters are also affected by the frequency and the amplitude of the dynamic load applied to the soil. The in-situ tests compliments the laboratory testing in the evaluation of the dynamic soil parameters. Although, correlations can be used to estimate the in-situ parameters but a direct measurement is necessary. To develop a greater confidence of the results of the in-situ tests, it is helpful to compare the field results to conventional laboratory tests. In the RC testing, the effect of base stiffness has a significant effect on shear modulus and damping values. In literature, only two studies have shown the effect of base fixidity. In this thesis, the issue is addressed by testing sand and clay sample on traditional bench and isolation table. In addition to base fixidity, coupling between the specimen and base platen is also very critical. Radial blades in top and bottom platen are introduced along with porous stone fixed underneath the blades. Aluminum probes are recommended for the calibration of the RC device, however, the effect on shear modulus and damping as function of shear strain is not well studied. Therefore, the stiff probe is tested from low to large strains and effect on damping ratio is studied. Finally, a new BE method is proposed to understand the estimation of shear wave velocity at higher frequencies. Due to the large variation in the interpretation of the BE tests results, there is no standard method for the estimation of the shear wave velocity. In this thesis, a new calibration procedure using state of the art laser vibrometer is used to understand the bending behavior of benders in air and in tip to tip configuration. Shear wave velocity comparison between RC and BE tests is done in usual practice, however, the frequency effects from these two tests are not well stated. In this study, the frequency effects are studied and a new methodology, modified frequency domain method, is introduced and tested on dry specimen. The results of the BE tests match well with the RC test values. MASW is a practiced field test to evaluate the shear wave velocity profile for geomaterials, however, the effect of frequency in the case of an anomaly has not been well understood. Therefore, this study uses numerical simulations and a lab scale model to study these effects. In addition, the effect of actual accelerometers on the measurements is studied for the first time using a high frequency laser vibrometer. The frequency effects in field theory of the MASW and SCPT is also studied to address the actual limitations in the analysis of SCPT data without the consideration of frequency effects. Based on the objective, this research focuses on: (1) the study of the laboratory resonant column and bender element tests, (2) numerical simulations and laboratory surface waves testing, and (3) field testing using surface waves and seismic cone penetration method for the estimation of shear wave parameters with emphasis on the frequency effects. An important aspect of the laboratory testing is the calibration of the equipment. Standard procedures are available for the calibration of the resonant column (RC) device, however, the same is not true for the bender element (BE). In this study, the bender elements are calibrated using three different configurations, tip-to-tip, aluminum rods, and using state-of-art laser vibrometer. The State of art laser vibrometer is used to characterize the bending behavior of the bender elements showing the resonance frequency of 12 kHz and damping of 2 % when vibrating in air. The top and bottom platen of RC device were modified to allow better coupling between the specimen and benders. Radial blades were introduced to account for coupling of stiff clay specimens. Four different soils (sand, stiff clay, mine paste, and leda clay) were tested in this study. The results of the tests, from the RC and the BE tests, were analyzed in the time and the frequency domains. Comparison of the results show, a maximum of 45 $\%$ difference in the velocity obtained from the RC and BE tests. Leda clay tests were done on the modified base platens and the difference in the Vs between the RC and BE is 6% compared to the stiff clay specimen where the difference is 28% To study the difference in the Vs values between the RC and BE, a new modified frequency domain method for BE testing is presented. The method was applied to the sand specimen. The sample is excited with a frequency sweep ranging from 0 to 52 kHz and change in unwrapped phase, between the input excitation and output response, is evaluated outside the range of resonant peaks of the specimen. The Vs values from the two tests match well for the frequency range between 29 and 23 kHz, with overall less than 10 % error for the range of confinement range studied in this thesis. Numerical simulations on homogeneous and non-homogeneous medium showed the change in the phase velocity of the Rayleigh waves (R-waves) due to the presence of a void. To introduce non-homogeneity, voids of various size and depth were used. Nine numerical models were analyzed, change in the phase velocity as a function of frequency was observed. A new methodology was introduced in which the receivers were divided into three sections, before, on-top, and after the void. Results from the dispersion curves show that the change in the phase velocity (function of frequency) is between 3% to 50% for different void width and depth. Multichannel analysis of surface waves (MASW) test method was used as the geophysical testing method. The laboratory tests were conducted using three different configurations on sandbox. Two tests involved use of accelerometers as receivers, however, the input source was different. While the third test consisted of using state of art laser vibrometer as receiver. Using the laser vibrometer, 96 surface responses were recorded compared to 12 using accelerometers. The results from the laboratory MASW test showed the frequency effect on the measurements due to the source used in this method. Coupling of the geophone/transducer in surface wave testing is an important issue. Results from the lab test using laser vibrometer showed that the mass loading effect of accelerometer affects the frequency content of the signal. The field MASW and the SCPT tests were done at the University of Waterloo Columbia Lake Test Site (UW-CLTS). The comparison of shear wave velocity from the field MASW and the SCPT shows the average shear wave velocity profile from the two tests, however, importance in not paid to the frequency of the input signal and main frequency difference between the MASW and SCPT tests. In this study, the frequency spectrum from the MASW and the SCPT tests data were analyzed to understand the change in the shear wave velocity at different depths. From the analysis, the percentage change in shear wave velocity between MASW line 1 and SCPT 1 and 2 is more than 90 % for depths between 0 and 2 m, while it reduces to 10 % for depths between 7 and 13 m.

Download or read book Dynamic Geotechnical Testing written by M. L. Silver and published by ASTM International. This book was released on 1978 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Frontiers in Geotechnical Engineering written by Madhavi Latha G. and published by Springer. This book was released on 2019-02-11 with total page 453 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains contributions by eminent researchers in the field of geotechnical engineering. The chapters of this book are based on the keynote and theme lectures delivered at the Indian Geotechnical Conference 2018, and discuss the recent issues and challenges, while providing perspective on the possible solutions and future directions. A strong emphasis is placed on proving connections between academic research and field practice, with many examples and case studies. Topics covered in this volume include contemporary infrastructural challenges, underground space utilization, sustainable construction, dealing with problematic soils and situations and geo-environmental issues including landfills. This book will be of interest to researchers, practitioners and students alike.

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 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 Dynamic Geotechnical Testing II written by Ronald J. Ebelhar and published by ASTM International. This book was released on 1994 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Soil Dynamics and Liquefaction written by A.S. Cakmak and published by Elsevier. This book was released on 2014-04-11 with total page 387 pages. Available in PDF, EPUB and Kindle. Book excerpt: Despite advances in the field of geotechnical earthquake engineering, earthquakes continue to cause loss of life and property in one part of the world or another. The Third International Conference on Soil Dynamics and Earthquake Engineering, Princeton University, Princeton, New Jersey, USA, 22nd to 24th June 1987, provided an opportunity for participants from all over the world to share their expertise to enhance the role of mechanics and other disciplines as they relate to earthquake engineering. The edited proceedings of the conference are published in four volumes. This volume covers: Constitutive Relations in Soil Dynamics, Liquefaction of Soils, and Experimental Soil Dynamics. With its companion volumes, it is hoped that it will contribute to the further development of techniques, methods and innovative approaches in soil dynamics and earthquake engineering.

Download or read book Vibration Effects of Earthquakes on Soils and Foundations written by ASTM Committee D-18 on Soil and Rock for Engineering Purposes. Subcommittee 9 on Dynamic Properties of Soils and published by Philadelphia : The Society. This book was released on 1969 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Geotechnical Earthquake Engineering written by Ikuo Towhata and published by Springer Science & Business Media. This book was released on 2008-12-19 with total page 684 pages. Available in PDF, EPUB and Kindle. Book excerpt: This fascinating new book examines the issues of earthquake geotechnical engineering in a comprehensive way. It summarizes the present knowledge on earthquake hazards and their causative mechanisms as well as a number of other relevant topics. Information obtained from earthquake damage investigation (such as ground motion, landslides, earth pressure, fault action, or liquefaction) as well as data from laboratory tests and field investigation is supplied, together with exercises/questions.

Download or read book The Behavior of Soils Under Dynamic Loadings Final report on laboratory studies written by Massachusetts Institute of Technology. Soil Mechanics Laboratory and published by . This book was released on 1953 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Soil Behaviour in Earthquake Geotechnics written by Kenji Ishihara and published by Oxford University Press, USA. This book was released on 1996 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: This highly topical book, written by a leading Japanese author, provides a comprehensive study of current research in soil dynamics for earthquake engineering. The behaviour of the ground on which structures are built during earthquake conditions is crucial to understanding the behaviour of those structures. This well-illustrated text summarizes current knowledge of the subject, presenting material accumulated by Japanese and other researchers over recent years. It comprehensively covers theory, laboratory tests, and field work. It also includes helpful guidelines for civil engineers undertaking groundwork to protect structures in potential earthquake zones.