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Articles 12451 - 12480 of 13029

Full-Text Articles in Engineering

Offshore Caissons On Porous Saturated Soil, George Gazetas, Emmanuel Petrakis Apr 1981

Offshore Caissons On Porous Saturated Soil, George Gazetas, Emmanuel Petrakis

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

While currently available methods of dynamic soil-foundation interaction idealize the soil as a continuum, this paper presents a general theory to obtain the dynamic response of offshore caissons resting on a saturated or nearly saturated poroelastic medium. The model, based on Biot's theory, considers the compressibility of both solid and fluid phase and assumes that the fluid flow is governed by Darcy's Law for an isotropic medium. Results are presented as plots of normalized amplitudes of displacement load or rotation-moment ratios for a rigid strip founded on a dense coarse sand. The results demonstrate that fluid compressibility, which is primarily …

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Seismic Design Of The San Francisco Ocean Outfall, O. H. Gilbert Jr., Y. Eisenberg, D. D. Treadwell Apr 1981

Seismic Design Of The San Francisco Ocean Outfall, O. H. Gilbert Jr., Y. Eisenberg, D. D. Treadwell

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

San Francisco's Southwest Ocean Outfall will extend four miles into the Pacific Ocean. Offshore, the Outfall will cross the San Andreas Fault zone. Major design concerns for the 12-foot inside diameter reinforced concrete pipe included seismic foundation stability, backfill liquefaction, and rupture by fault displacement. Foundation stability was achieved by selection of adequate embedment depths. A coarse pervious backfill to preclude liquefaction-induced pore water pressure gradients was selected based on analyses with the computer program APOLLO. Special joints were designed within and adjacent to the fault zone to limit damage due to fault rupture and to accommodate deformations away from …

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Exceptional Issues In Offshore Earthquake Geotechnology, R. G. Bea Apr 1981

Exceptional Issues In Offshore Earthquake Geotechnology, R. G. Bea

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

This Moderator's Report reviews the state-of-the-art report and papers submitted to the session on Offshore Earthquake Geotechnology. Selection of earthquake intensity and characteristics of ground motions for design of offshore structures, offshore source and attenuation characterizations, local site effects, and structure-foundation-soil interactions that may be exceptional to the offshore environment are discussed.

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Session 6: Discussion And Replies, Multiple Authors Apr 1981

Session 6: Discussion And Replies, Multiple Authors

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

No abstract provided.

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Seismic Analysis As A Tool In The Design Of Two Earth Dams, A. Yziquel, M. Lino, G. Post, B. Tardieu Apr 1981

Seismic Analysis As A Tool In The Design Of Two Earth Dams, A. Yziquel, M. Lino, G. Post, B. Tardieu

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

Two dynamic analysis studies of embankment dams are described. One dam is 43m high on alluvium, the other is 140m high on a rock foundation in a highly seismic area. The main emphasis is on the practical nature of the analytical methods and their value as design tools. The earthquake design features of both projects are described and the closing paragraphs attempt to draw attention to the main points to be considered when running an earthquake analysis of earth dams.

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Seismic Analysis Of Spinney Mountain Dam, J. V. Williamson, M. E. Shaffer Apr 1981

Seismic Analysis Of Spinney Mountain Dam, J. V. Williamson, M. E. Shaffer

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

The Spinney Mountain Dam, now under construction in central Colorado, is a zoned earth embankment with a maximum height of 95 feet above foundation. Detailed geological investigations revealed rejuvenated sediments of nearby older faults, which have undergone tectonic movement within the past 13,000 to 30,000 years and hence are considered capable. Studies indicate the largest earthquake expected on the controlling fault would have a Richter Magnitude of about 6.2, implying peak ground accelerations at the site of about 0.6g and a 15-second duration of strong motion. Displacement on a branch of the main capable fault during such an event is …

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Longitudinal Seismic Behavior Of Earth Dams, A. M. Abdei-Ghaffar Apr 1981

Longitudinal Seismic Behavior Of Earth Dams, A. M. Abdei-Ghaffar

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

Earthquake-induced vibration in earth darns in a direction parallel to the darn axis is studied using analytical elastic models. The non-homogeneity of the darn materials is taken into account by assuming specific variations of the elastic moduli along the depth due to the confining pressure. Based on the models, a rational procedure is developed to estimate dynamic stresses and strains (both shear and normal) and corresponding elastic moduli and damping factors for earth darns from their hysteretic responses to real earthquakes, utilizing the hysteresis loops from the crest and base records. This leads to a study of the variation of …

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Effective Stress Analyses Of Seismic Stability, E. Kavazanjian Jr., J. L. Chameau Apr 1981

Effective Stress Analyses Of Seismic Stability, E. Kavazanjian Jr., J. L. Chameau

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

The factors involved in performing effective stress analysis of seismic stability problems are examined. The advantages of using a stochastic model for pore pressure generation are discussed. A simplified analysis of a hypothetical case is outlined to illustrate the factors involved in performing effective stress stability analysis.

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Estimation Of Displacements Of Rockfill Dams Due To Seismic Shaking, J. L. Vonthun, C. W. Harris Apr 1981

Estimation Of Displacements Of Rockfill Dams Due To Seismic Shaking, J. L. Vonthun, C. W. Harris

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

A computer code for estimation of displacement of sliding surfaces during dynamic loading is discussed. The procedure allows selective incorporation of the effects of horizontal and vertical inertial forces, excess pore pressure development, hydrodynamic forces, shear strength reduction, and dilation. The relative effect of these parameters on the computed displacements can be readily determined for alternative design layouts or material behavior assumptions.

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Seismic Deformation Of Dams By Correlative Methods, Y. K. Lin, K. V. Rodda, C. W. Perry, D. K. Gill Apr 1981

Seismic Deformation Of Dams By Correlative Methods, Y. K. Lin, K. V. Rodda, C. W. Perry, D. K. Gill

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

Analyses are presented of the anticipated earthquake performance of three generally similar earth dams, situated in a seismically active area of northern California. The series of analyses illustrates a cost-effective approach which involved full-scale finite element analyses of one dam, and the use of limited dynamic analysis techniques and correlations to evaluate the other two. The simplified techniques were applied only after testing them against the finite element analyses, information is also presented on how the results of simplified and full-scale dynamic analysis procedures correlate.

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On The Dynamic Stability Of Block Sliding On Rock Slopes, Wang Sijing, Zhan Juming Apr 1981

On The Dynamic Stability Of Block Sliding On Rock Slopes, Wang Sijing, Zhan Juming

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

This paper deals with the dynamic analysis of block sliding on rock slope along plane surfaces, such as joints, bedding planes and faults. According to the results obtained in the shaking tests the dynamic friction along a sliding surface is dependent on the velocity of relative motion, and can be determined by using the proposed method of test. On the basis of conducted experiments a differential equation was established. The integration of the dynamics equation by numerical method provides a basis for evaluation of slope stability in terms of critical displacement and dynamic instability.

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On The Use Of Nonlinear Soil Models, Albert T. F. Chen Apr 1981

On The Use Of Nonlinear Soil Models, Albert T. F. Chen

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

The basic definitions of, and the differences between, currently available soil models are reviewed. These models are applied to site response analyses where two depths and two levels of base input motion are considered. Computational results are presented and compared with regard to the effects of using different soil models on computed site response. Other implications resulting from the choice of soil model for seismic response analysis are also discussed.

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Permanent Deformation Of Earth Dams Under Earthquakes, William Y. J. Shieh, Rodney J. Huang Apr 1981

Permanent Deformation Of Earth Dams Under Earthquakes, William Y. J. Shieh, Rodney J. Huang

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

Assessment of dam embankment deformation by various methods such as those proposed by Newmark, Ambraseys and Seed was reviewed herewith. A simple method based on dynamic response spectrum analyses by step-by-step integration technique is proposed for independent permanent deformation evaluation. The proposed method assumes that failure occurs on a well-defined slip surface and that the material behaves elastically at stress level below failure but develops a perfectly plastic behavior above the yield acceleration. The results of the proposed method were compared with those obtained from other method for actual examples. Favorable agreement on the analytical results was achieved.

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Analysis Of Dynamic Shear Strain Distributed In Three Dimensional Earthdam Models, T. Ohmachi Apr 1981

Analysis Of Dynamic Shear Strain Distributed In Three Dimensional Earthdam Models, T. Ohmachi

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

Dynamic shear strain distribution have been evaluated and illustrated for three dimensional earthdam models. The analysis method applied here is a simplified finite element method, which has proved to give vibration modes of an earthdam to a satisfactory level of accuracy by involving a smaller number of degrees of freedom. Mass and stiffness matrices of a dam have been formulated for two types of the shear modulus distribution, one uniform and the other linearly increasing with depth below the crest. Both magnitude and location of the maximum shear strain have been discussed in relation to topography of dam sites.

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A Simplified Procedure For Evaluating Maximum Response Of Soil Layer During An Earthquake, Fu Shengcong, Jiang Jingbei Apr 1981

A Simplified Procedure For Evaluating Maximum Response Of Soil Layer During An Earthquake, Fu Shengcong, Jiang Jingbei

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

In this paper, the horizontally stratified soil layers are simplified as a shearing type multidegree of freedom linear system. The transfer function of the system is determined in accordance with the statistic analysis of the result from the mode superposition method of soil layer earthquake response. By referring to the method of finding the extreme value in probabilistic theory, a response spectrum corresponding to the power spectral density of soil layers is given. At the same time, distributions of maximum response values of acceleration, displacement, shearing strain and shearing stress of the soil layers along the depth are given according …

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Session 7: Discussion And Replies, Multiple Authors Apr 1981

Session 7: Discussion And Replies, Multiple Authors

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

No abstract provided.

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Source Mechanism And Seismic Effect Of Tangshan Earthquake, Hong-Qi Fang, Xin-Kwan Miao, Shu-Dong Zhao Apr 1981

Source Mechanism And Seismic Effect Of Tangshan Earthquake, Hong-Qi Fang, Xin-Kwan Miao, Shu-Dong Zhao

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

By analyzing the seismic mechanism of the Tangshan earthquake and its pattern of movement through the study of ground deformation and ground strain of the Tangshan earthquake area it is clear that the breeding and occurrence of this event are controlled by a long-term intense active fault zone. By the ground deformation, displacement, tectonic features and seismic effects after the event, this causative fault is known to be composed of a group of NNE trending right turn strike-slip faults and thus we call it the Tangshan active fault zone.

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Observed And Predicted Liquefaction Of A Sand Stratum, A. Jaime, M. P. Romo, L. Montañez Apr 1981

Observed And Predicted Liquefaction Of A Sand Stratum, A. Jaime, M. P. Romo, L. Montañez

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

Field observations and preliminary studies had led to the conclusion that the sand stratum liquefied only in a limited area during the March 14, 1979 earthquake. Further field studies revealed the presence of the sand layer throughout the Enmedio Island. This fact raised questions as to whether the sand liquefied or not in the whole area. To clarify this question, a research program which included cyclic triaxial testing and numerical analyses was undertaken. The results of this study show that the sand layer did liquefy through the Island; however, due to differences in stratigraphic characteristics, superficial signs of liquefaction were …

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Local Site Behaviour In The 1976 Friuli Earthquake, M. Basili, V. Gorelli, F. Muzzi Apr 1981

Local Site Behaviour In The 1976 Friuli Earthquake, M. Basili, V. Gorelli, F. Muzzi

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

Soon after the main shock of Friuli, Italy, May 6th 1976 earthquake, two strong motion recorders accelerographs were installed in two sites about 650 meters distant one from the other. One instrument was installed on hard outcropping rock, the other at the surface of an alluvial deposit 20+25 meters thick underlain by a sloping bedrock. Among the numerous records obtained three aftershocks of magnitude about 6 and hypocentral distance within 20 Km, are investigated by comparing maximum accelerations, durations, Arias intensity and Husid ratios. A new numerical tool is proposed which consists of a series of plots of the Husid …

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Observations And Analysis On Building Settlement Due To Tangshan Earthquake, Huang Xiling Apr 1981

Observations And Analysis On Building Settlement Due To Tangshan Earthquake, Huang Xiling

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

This paper describes the significant settlement of buildings on saturated soft clay due to Tangshan earthquake. Results of dynamic triaxial tests and analysis of stress in subsoil will be given. The factors which influence the settlement will also be discussed herein.

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Liquefaction Of The Enmedio Island Soil Deposits, A. Jaime, L. Montañez, M. P. Romo Apr 1981

Liquefaction Of The Enmedio Island Soil Deposits, A. Jaime, L. Montañez, M. P. Romo

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

The results of field testing and of simplified liquefaction analyses of the Enmedio Island soil deposits are presented and discussed in this paper. It is found that for this case history simple criteria for assessing liquefaction potential yield results in accord with field behavior.

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Geotechnical And Strong Motion Aspects Of Recent Indian Earthquakes, Jai Krishna Apr 1981

Geotechnical And Strong Motion Aspects Of Recent Indian Earthquakes, Jai Krishna

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

India had many strong earthquakes in the past. The paper describes some strong motion and geotechnical aspects of Indian earthquakes.

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Geomechanics Of Reservoir Induced Seismicity, Thomas Vladut Apr 1981

Geomechanics Of Reservoir Induced Seismicity, Thomas Vladut

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

Although induced seismicity associated with the impounding of reservoirs is a relatively rare phenomenon, it should nevertheless be taken into account, particularly in the design of dams located in aseismic zones. The operation of dams is not significantly affected by induced activities: the main concern arises in situations where unexpected events might affect the behavior of the construction due to soil liquefaction or might affect slope stability. This paper reviews the principal elements which are considered to affect the occurrence of the phenomenon: the weight of the water storage, and the development of pore pressure under the storage. Both elements …

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Planning Instrumentation Monitoring In Dams, S. N. Guru Rau, R. K. Varma Apr 1981

Planning Instrumentation Monitoring In Dams, S. N. Guru Rau, R. K. Varma

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

This paper outlines the seismic instrumentation being adopted for river valley projects in India, More than 60% of Indian sub-continent lies in an active seismic belt. Of this the middle and lower Himalayas constitute a major area wherein lies a huge untapped hydro-power potential, Being primarily constituted of younger rock formations, frequented by faults, thursts and shear zones and lying in a high seismic risk zone, observations through instruments play a significant role in perspective planning of projects in this area. Setting up of seismological observatories in advance of construction of dam projects, forms a part of investigative planning to …

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Dynamic Consolidation Of Liquefiable Sands, R. K. M. Bhandari Apr 1981

Dynamic Consolidation Of Liquefiable Sands, R. K. M. Bhandari

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

The Subsoils underneath a tank were improved by dynamic consolidation to density levels required to resist earthquake induced liquefaction. The paper presents seismic analysis of the refinery region, simple liquefaction potential analysis using modified depth reduction factors and performance of the tank resting on the densified ground. The degree of uniformity of compaction achieved by the dynamic consolidation has been discussed.

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Local Soil Effects And Liquefaction In The 1978 Thessaloniki Earthquakes, George Gazetas, John Botsis Apr 1981

Local Soil Effects And Liquefaction In The 1978 Thessaloniki Earthquakes, George Gazetas, John Botsis

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

The geotechnical aspects of three earthquakes that struck the city of Thessaloniki, Greece, on May 25, June 20 and July 4, 1978 are presented. General background information on the observed damage, seismic history and geology of the area is followed by detailed description of soil profiles, structural characteristics and accelerograms of ground motions recorded at three sites. Acceleration spectra are then examined and compared in order to assess the degree to which local and regional geology and soil-structure interaction affected the recorded motion. Finally, the possibility of liquefaction having taken place in a 6 m-thick saturated loose layer of silty …

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Engineering Seismology Aspects Of The M-6.5, Southern Italy Earthquake Of Nov. 23, 1980: A Preliminary Review, E. Faccioli Apr 1981

Engineering Seismology Aspects Of The M-6.5, Southern Italy Earthquake Of Nov. 23, 1980: A Preliminary Review, E. Faccioli

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

The paper provides an overview of salient engineering seismology features of the earthquake, which was one of the major seismic catastrophes occurring in Italy in this century. After a short description of the characteristics of the earthquake source and of the historical seismicity of the region, preliminary strong-motion and intensity data are presented. Aspects of geotechnical engineering interest include some large landslides in inhabited areas, and notable cases of correlation between severity of damage and local soil conditions and topography.

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Attenuation Of Ground Vibration Induced By Dynamical Machinery, S. J. Yang Apr 1981

Attenuation Of Ground Vibration Induced By Dynamical Machinery, S. J. Yang

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

Attenuation of ground vibration induced by dynamic machinery is investigated with fundamental theory established for both Rayleigh and body waves. Therefore, for determining such attenuation is established, in which the effects of both of them and a coefficient of attenuation of soil that makes the practical calculation easier are involved. A lot of data in relation to the surface vibration measured at some production shops and construction sites has proved that the developed formula more satisfactory than Bornitz's.

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Considerations About Some Aspects Of The 23rd November 1980 Earthquake, Filippo Ciuffi, Giuseppe Samela Apr 1981

Considerations About Some Aspects Of The 23rd November 1980 Earthquake, Filippo Ciuffi, Giuseppe Samela

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

The macroscopic effects of the earthquake of the 23rd of November 1980 in southern Italy are well-known. The purpose of this short paper is to present after about five months, some more exact testimonies with some considerations about numerous questions connected to the geotechnical and geological problems in seismic areas. We have to be precise that we, in this paper, contemplate the MURO LUCANO and CASTELGRANDE areas (in Basilicata) (fig. 1)

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Session 8: Discussions, Multiple Authors Apr 1981

Session 8: Discussions, Multiple Authors

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

No abstract provided.

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