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Articles 12331 - 12360 of 13029

Full-Text Articles in Engineering

Predicting Pore Pressure And Applications To Complex Loading Problems, Dwight A. Sangrey, Vincent P. Lascko Apr 1981

Predicting Pore Pressure And Applications To Complex Loading Problems, Dwight A. Sangrey, Vincent P. Lascko

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Methods for predicting and modeling the pore pressure response when soils are subjected to cyclic loading are described. These predictions include both the limiting states of pore pressure and the intermediate stages of development as a function of number of cycles. Applications of pore pressure prediction in effective stress methods are illustrated for a group of problems including sequencing of irregular loading, degradation of stress-strain modulus, volume changes and strength changes.

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Response Of Non-Saturated Soil To Cyclic Loading, R. C. Chaney, H. Y. Fang Apr 1981

Response Of Non-Saturated Soil To Cyclic Loading, R. C. Chaney, H. Y. Fang

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

The response of partially saturated and dry sand materials under cyclic loading is controlled by the compressibility of the pore fluid. For dry sand the limiting axial and volumetric strain occurs within 5 to 15 cycles of load application and is a function of the number of cycles of cyclic stress, relative density, and effective consolidation pressure. In addition the axial strain is shown to be independent of the consolidation stress ratio for loose sand and decreases with increasing consolidation stress ratio for dense sand under a constant cyclic stress.

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Dilation Angle And Liquefaction Potential, Y. P. Vaid, P. M. Byrne, J. M. O. Hughes Apr 1981

Dilation Angle And Liquefaction Potential, Y. P. Vaid, P. M. Byrne, J. M. O. Hughes

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Most of our understandin9 of the liquefaction phenomenon has come from laboratory tests. It would be desirable to express liquefaction resistance in terms of a parameter which can be measured both in the laboratory and in the field. It is proposed that the dilation angle or expansion rate of the sand is such a parameter. It is readily measured in the laboratory from drained simple shear or triaxial tests and in the field from self boring pressuremeter tests. Based on laboratory tests on Ottawa sand a chart is presented for estimating the liquefaction resistance of saturated sands in terms of …

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Macroscopic Approach To Soil Liquefaction, Zhong-Qi Wang Apr 1981

Macroscopic Approach To Soil Liquefaction, Zhong-Qi Wang

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

In view of the fact that microscopic liquefaction cannot be equated with the macroscopic one; further, owing to the unsolved difficulties in taking undisturbed samples of sand end in performing laboratory tenting of liquefaction, the author has tried to search after new practical way to assess soil liquefaction potential by macroscopic approach. This paper presents a preliminary study winch can coordinate each other with the laboratory microscopic procedures so as to make more reliable prediction to liquefaction potential and assessment of its seismic effect.

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In-Situ Undisturbed Sand Sampling By Radial Freezing For Liquefaction Analysis, R. Da Rolt, L. Lojelo, F. Muzzi, G. Spat Apr 1981

In-Situ Undisturbed Sand Sampling By Radial Freezing For Liquefaction Analysis, R. Da Rolt, L. Lojelo, F. Muzzi, G. Spat

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

The authors experimented in laboratory that if radial freezing with free drainage is performed under an effective confining pressure of 100 kPa only an increase of the order of 0.5% of volumetric strain takes place going from the unfrozen to the frozen condition. The sample comes back to the original dimension after thawing. The displacements of the sample were measured by radiographs of a lead shot network properly built inside the sample. The technique suggested by Yoshimi and al. (1977) to freeze in situ a column of saturated sands was also verified and optimized in laboratory by simulating in a …

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Analysis Of Rigid Retaining Walls During Earthquakes, Shamsher Prakash Apr 1981

Analysis Of Rigid Retaining Walls During Earthquakes, Shamsher Prakash

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Retaining walls experience changed pressures and undergo displacements as well during earthquakes. Both the questions have been discussed in detail in this paper. Increments in active earth pressures have been correlated with peak ground velocity and a method to compute seismic coefficient to be used in the Mononabe method has been proposed. The question of point of application of the dynamic increment has also been examined in detail. There are three methods to compute displacements of rigid retaining walls, a) based on Newmark's approach of a sliding block, b) computation of translation only and c) computation of displacements due only …

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Effect Of Vibration On Pile Uplift Capacity, P. J. Moore, J. P. Piper Apr 1981

Effect Of Vibration On Pile Uplift Capacity, P. J. Moore, J. P. Piper

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

An experimental and theoretical study has been carried out to examine the effects of vibration frequency and amplitude as well as magnitude of static applied load on the uplift capacity of piles driven into a sandy soil. The theoretical solution was developed using a lumped parameter model with viscous damping. The results, both theoretical and experimental, indicate that the displacement amplitude required to cause uplift failure of the pile, decreases as the vibration frequency increases. This trend was shown to be significantly dependent upon the natural frequency of the pile-soil system and to a lesser degree, upon the damping ratio. …

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Dynamic Analysis Of Foundations For Heavy Duty Diesel Engines, N. S. V. Kameswara Rao Apr 1981

Dynamic Analysis Of Foundations For Heavy Duty Diesel Engines, N. S. V. Kameswara Rao

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Coupled motion analysis of Machine-Foundation-Soil systems subjected to periodic dynamic forces and moments which are of general nature (both in amplitudes and periods) has been carried out using Fourier analysis and numerical techniques. Free vibration as well as forced vibration analysis in all the coupled and uncoupled modes of the system has been presented. The procedure is illustrated in the case of an eight cylinder heavy duty diesel engine generator assembly and results have been graphically shown in terms of frequency ratios and maximum steady state responses in the all the relevant modes of vibration.

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Soil-Pile Interaction In Vertical Vibration, Y. Gyoten, K. Mizuhata, T. Fukusumi, H. Nozoe, T. Inoue, T. Mizuno Apr 1981

Soil-Pile Interaction In Vertical Vibration, Y. Gyoten, K. Mizuhata, T. Fukusumi, H. Nozoe, T. Inoue, T. Mizuno

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

This paper deals with the theoretical study concerning soil-pile interaction in vertical vibration for both the floating pile and the pile group. The analysis is made by applying the elastic wave theory to the viscoelastic layer overlying on the rigid bedrock. Further, the displacement responses of the pile and the complex stiffness at the pile head subjected to the harmonic excitation at the top of the pile are obtained for various parameters.

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Stiffness Coefficients For Embedded Footings, L. S. Chickanagappa Apr 1981

Stiffness Coefficients For Embedded Footings, L. S. Chickanagappa

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Mindlin’s theory and Steinbrenner’s approximation are used to evaluate the static stiffness coefficients for embedded footings subjected to vertical oscillations. The footing is assumed to be embedded in an elastic layer underlain by a rigid base. The solution presented is simple and is amenable to hand calculations. It compares well with other rigorous solutions, in the analysis presented in the paper the shape of the footing can be easily taken into account. The method gives a solution which lies between the finite element solution and the rigorous closed form solutions.

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Session 4: Discussion And Replies, Multiple Authors Apr 1981

Session 4: Discussion And Replies, Multiple Authors

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

No abstract provided.

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Free Response Of Shells On Flexible Foundation, R. M. Belkune, J. C. Vyas Apr 1981

Free Response Of Shells On Flexible Foundation, R. M. Belkune, J. C. Vyas

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Free response of axisymmetric shells resting on flexible foundation in their asymmetric modes is studied using Finite Elements based on harmonic formulation. Influence of various parameters, such as subgrade modulus, proximity of boundary, density ratio, shear wave velocity, embedment of structure and depth of flexible foundation., on free response is studied. Axisymmetric interface element with harmonic functions is developed and introduced between the raft slab and foundation media.

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Dynamic And Earthquake Geotechnical Centrifuge Modelling, A. N. Schofield Apr 1981

Dynamic And Earthquake Geotechnical Centrifuge Modelling, A. N. Schofield

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

This state of art review discusses scaling principles for dynamic and earthquake geotechnical centrifuge models that have been known for many years, and shows how the new emphasis on modelling of models using reconstituted soil helps to reduce the difficulties of verification of these principles. It is suggested that models made of reconstituted soil can exhibit a wide range of behavior that is important in the field. In particular it is suggested that liquefaction and cracking are related phenomena which can both be modelled.

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Offshore Earthquake Geotechnology — First Part, P. B. Selnes Apr 1981

Offshore Earthquake Geotechnology — First Part, P. B. Selnes

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

This first part of the paper outlines the problems encountered offshore compared to onshore. The most important difference is the presence of water which changes the dynamic behavior of structures, introduces new forces, complicates the soil investigation and visual site inspection, and changes the characteristics of the earthquake ground motion. Furthermore, the structures offshore may be much larger than most onshore facilities, and other environmental loads may act simultaneously with an earthquake.

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Earthquake Resistance Of A Rockfill Dam, C. Bossoney, M. Balissat, E. G. Prater, J. Studer, N. Zingg Apr 1981

Earthquake Resistance Of A Rockfill Dam, C. Bossoney, M. Balissat, E. G. Prater, J. Studer, N. Zingg

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

The paper describes the investigation of the seismic safety of a 131 m high rock fill dam presently under construction across the Rio Chixoy in Guatemala. The dam is located in a region of high seismicity the recently active Motagua fault being only 40 km distant. Due to the possibility of high peak ground accelerations it was considered necessary to conduct a full dynamic analysis, which was carried out in stages following the Seed-Lee-Idriss method, the latter being modified where it was deemed necessary.

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Pore Pressure Analysis For An Earth Dam During Earthquake, R. C. Sonpal, A. A. Dave Apr 1981

Pore Pressure Analysis For An Earth Dam During Earthquake, R. C. Sonpal, A. A. Dave

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

An analytical study of the pattern of variation in the pore pressures within an embankment during earthquake, based upon seismic analysis by the rigid body response method and by the elastic body response method using ICL 1901 A computer is presented herein. The pore pressure contours before and during an earthquake are presented for an upstream slope of Tapar dam situated in seismically active zone in West India.

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Session 7: Moderator's Report, W. F. Marcuson Iii Apr 1981

Session 7: Moderator's Report, W. F. Marcuson Iii

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

No abstract provided.

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Measurements Of Lnsitu Pore Water Pressures During Earthquakes, K. Ishihara Apr 1981

Measurements Of Lnsitu Pore Water Pressures During Earthquakes, K. Ishihara

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

By installing several sets of piezometers and a seismograph in a recently reclaimed sand deposit on Ohgishima Island near Tokyo, Japan, an attempt was made to monitor pore water pressures as well as horizontal accelerations during earthquakes. The limited data obtained thus far have indicated that virtually no pore water could build up in the loose sand deposit with a small scale shaking having a maximum horizontal acceleration of 45 gal on the ground surface.

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Zonation Of Central U. S. Earthquake Sources, G. L. Hempen, M. J. Klosterman, B. H. Moore, John D. Rockaway, Gerald B. Rupert Apr 1981

Zonation Of Central U. S. Earthquake Sources, G. L. Hempen, M. J. Klosterman, B. H. Moore, John D. Rockaway, Gerald B. Rupert

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

A variety of analyses are utilized in developing potential earthquake ground shaking at a specific location. Geological procedures for estimating causes of earthquakes are fundamental to the prediction of ground motions. Evaluations of geologic factors compliment mathematical assessments of seismological data. Earthquake potential in the Central United States is predicted using the concept of seismic source zones due to the difficulty of determining active faults. Resolution of these geographic source zones is dependent upon knowledge of historic seismicity, pertinent geologic features, and causative tectonics. Regardless of the method used to delineate source zones, these zones must be geologically and seismologically …

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Session 9: Moderator's Report, Umesh Chandra Apr 1981

Session 9: Moderator's Report, Umesh Chandra

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

No abstract provided.

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Session 9: Closing Remarks, T. Kuppusamy Apr 1981

Session 9: Closing Remarks, T. Kuppusamy

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

No abstract provided.

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Dynamically Coupled Percolation And Deformation Analysis Of Earth Dams, Z. J. Shen Apr 1981

Dynamically Coupled Percolation And Deformation Analysis Of Earth Dams, Z. J. Shen

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

An effective stress method using two-dimensional finite elements is presented for predicting the generation and dissipation of pore water pressure coupled with deformation in saturated sands under earthquake shaking. The method has been used to analyze the post-earthquake slide of upstream slope of Shimenling earth dam in Liaoning province during Haicheng earthquake on Feb. 4, 1975.

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Physical Modeling To Assess The Dynamic Behavior Of Rock Slopes, J. A. Wilson Apr 1981

Physical Modeling To Assess The Dynamic Behavior Of Rock Slopes, J. A. Wilson

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

The design of rock slopes in seismically active areas should consider the risk of earthquake loads. This study involved testing simple models of rock slopes on a hydraulic shaking table and displaying the results on time versus displacement curves. The results were compared with predicted displacements computed using equations available in the literature. At low frequencies and small amplitudes the predicted sliding rates compared very well with the rates observed during the testing. However as the frequencies and amplitudes were increased, the equations overestimated the displacements by gradually increasing amounts.

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Design Measures To Improve Performance Of Fill Dams Under Earthquake Loading, K. L. Logani Apr 1981

Design Measures To Improve Performance Of Fill Dams Under Earthquake Loading, K. L. Logani

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Fill dams of height 50 meters or more are increasingly being planned, designed and constructed in highly seismic areas of the world. These dams incorporate various earthquake design measures. The design measures have been critically examined. Design guides with respect to free board, core base width, crest width, type and material of core and material of shells have been reviewed. Some examples of actual changes made in the design, for the seismicity of the region have been given (Table II). Finally, a table of pertinent data of over 50 high dams located in highly seismic areas of the world is …

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Dynamic Properties Of Embankment Dams, M. Öner, M. Erdik Apr 1981

Dynamic Properties Of Embankment Dams, M. Öner, M. Erdik

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Forced vibration test result are presented for two large embankment dams. The results are compared with an approximately three dimensional finite element analysis. In addition a semi-empirical fundamental period expression is developed for use in the interpretation of the available natural period data. The period expression developed is based on the shear wedge solution for an inhomogeneous medium and takes the effect of the third dimension into account.

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Rockfill Dam Stability Problems In A Seismic Zone, A. Moroianu, V. Perlea Apr 1981

Rockfill Dam Stability Problems In A Seismic Zone, A. Moroianu, V. Perlea

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

In the close vicinity of the great shock, March 4, 1977, in Vrancea region, Romania, one of the biggest shocks felt recently in Europe, two rockfill dams 120 m and, respectively, 70 m high with clayey cores are being constructed. In the paper, some problems arised by the design of these dams from earthquake engineering point of view are presented.

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No Tension Approach To Define Failure Phenomena For Rockfill Dam Subjected To Earthquake Loading, K. G. Bhatia, R. Natarajan Apr 1981

No Tension Approach To Define Failure Phenomena For Rockfill Dam Subjected To Earthquake Loading, K. G. Bhatia, R. Natarajan

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

It has been observed that actual behavior of Rockfill dams during earthquake is much different than that obtained by elastic analysis. No tension approach has thus been developed to overcome the shortfalls of elastic analysis. Using no tension approach redistribution of stresses are obtained which help in defining the failure pattern of the dam' subjected to a given seismic acceleration or in other words the failure acceleration is obtained for a given dam subjected to earthquake forces. Various dam models having different upstream and downstream slopes are analyzed using finite element technique. The input earthquake motion has been considered as …

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Seismic Stability Indices Of Earth Structure, M. P. Singh Apr 1981

Seismic Stability Indices Of Earth Structure, M. P. Singh

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Indices like cyclic damage and factor of safety are often used to quantify stability of soil systems subjected to earthquake loads. The methods used to obtain these indices are described; the relationship between cyclic damage and factor of safety through the concept of uniform stress equivalent time history is explored. For evaluation of a soil system design, the use of a direct approach is proposed. Evaluation of this approach by a simulation study is outlined. This approach, can use response spectra directly as seismic design input, and it provides an acceptable procedure for seismic stability prediction of soil systems.

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Embankment Design In Seismic Areas — Indian Practice, K. C. Thomas, S. N. Guru Rau, Bikram B. Raj Apr 1981

Embankment Design In Seismic Areas — Indian Practice, K. C. Thomas, S. N. Guru Rau, Bikram B. Raj

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

A number of river valley projects for the development of water and power resources, particularly in the Northern and North Eastern part of India, lie on the foothills of Himalayas which is seismically active. In the developmental activity of dam building, aseismic design of dam is therefore recognized and adopted. The paper presents the current Indian practice in the aseismic design of embankment dams with illustrations from studies carried out on some recent dams.

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Evaluation Of Seismic Stability Of Foundation Soils Under Revelstoke Earthfill Dam, K. S. Khilnani, P. M. Byrne Apr 1981

Evaluation Of Seismic Stability Of Foundation Soils Under Revelstoke Earthfill Dam, K. S. Khilnani, P. M. Byrne

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

The stability of the fine sands underlying the shells of the Revelstoke earthfill dam under earthquake shaking is discussed. The evaluation of liquefaction potential of the deposit was made from the field standard penetration resistance of the material. The dynamic analysis, made by a one-dimensional equivalent visco-elastic method, indicated that the sand under both the upstream and downstream shells had adequate liquefaction resistance and could be left in place. Adequate drainage of downstream fine sands was provided to further reduce its liquefaction potential.

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