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Articles 180151 - 180180 of 197987

Full-Text Articles in Engineering

Geotechnical Units And The Damages Caused By Earthquakes In Valparaiso - Chile, P. Acevedo, J. Monge, M. Astroza Mar 1991

Geotechnical Units And The Damages Caused By Earthquakes In Valparaiso - Chile, P. Acevedo, J. Monge, M. Astroza

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

The geotechnical units forming the foundation soil of Valparaiso city and constituting seven zones that exhibit different stratigraphic sequences are characterized. In addition, the evolution of the artificial backfilling’s located in the seaport is reported. The damages causes by Chile Earthquake of March 3, 1985 allow to establish for each zone the MSK intensities, which are varying between 7 1/2 and 8 1/2 in the flat-ground sector of Valparaiso, and between 7 1/4 and 7 1/2 in the hills. The major intensity in the flat sector is observed in areas whose artificial backfilling’s are exhibiting greater thickness and less consistency …

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Seismic Zonation Of India, L. S. Srivastava, S. Basu Mar 1991

Seismic Zonation Of India, L. S. Srivastava, S. Basu

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

The Himalayan belt, Indo-Gangetic Plains and Peninsular shield divide India in three major regions with decreasing seismic potential. The Indian Standard Criteria for Earthquake Resistant Design of Structures (IS: 1893-19841) incorporate a seismic zoning map (SZM) demarcating five seismic zones, which show zones with many islands, and prescribed design parameters for the delineated zones do not show consistent exceedance probability. A probabilistic analysis has been carried out and seismic design ground motion parameters have been estimated for 100 years’ service life, which do not support delineation of five zones with uniform ratio of seismic hazard among various zones. Four seismic …

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Subsurface Conditions In Memphis And Shelby County, Tennessee, T. S. Chang, K. W. Ng, H. Hwang, C. S. Lee Mar 1991

Subsurface Conditions In Memphis And Shelby County, Tennessee, T. S. Chang, K. W. Ng, H. Hwang, C. S. Lee

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

Investigation of subsurface conditions in the Memphis and Shelby County area, located within 100 miles south of the New Madrid seismic zone, was conducted by studying the soil data of more than 8,500 boring logs in the study area. These soil boring logs were collected from government agencies and private geotechnical companies so that the overall subsurface investigation was feasible and affordable. The subsurface conditions were presented in the standardized format of representative soil logs in accordance with a grid system applied to the study area. The results of the subsurface investigation are essential for regional seismic study such as …

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Dispersion Characteristics Of Elastic Waves In Saturated Soils, Shiming Wu, Longzhu Chen Mar 1991

Dispersion Characteristics Of Elastic Waves In Saturated Soils, Shiming Wu, Longzhu Chen

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

Based on the wave equations established by the authors, the dispersion characteristics of elastic waves in saturated soils are analyzed and verified by laboratory test and seismic survey in the field. The results can be used for determination of physical and mechanical parameters of saturated soils, such as, Poisson's ratio, depth for first appearance of full saturation, porosity and unit weight by measurement of wave velocities.

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Impact Response Of Granular Soils, C. J. Poran, J. A. Rodriguez, K. S. Heh Mar 1991

Impact Response Of Granular Soils, C. J. Poran, J. A. Rodriguez, K. S. Heh

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

The paper describes results from an extensive experimental model study of response of dry sand to impact of a rigid pounder. In the laboratory tests a circular steel pounder was repeatedly dropped on sand contained in a large tank. Measurements included pounder acceleration and soil pressure at impact, pounder settlement, and soil densities and strains. Effects of pounder drop height, weight and contact area were investigated. A method is presented for the evaluation of global dynamic stiffness of the so1l mass affected by the impact by calculating a dynamic settlement modulus (DSM). The DSM values are determined from integration of …

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A Study Of Blast Pressure From Underwater Borehole Blasting, T. S. Thandavamoorthy Mar 1991

A Study Of Blast Pressure From Underwater Borehole Blasting, T. S. Thandavamoorthy

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

The paper presents an experimental study conducted under laboratory conditions on the measurement of the pressure waves transmitted into water that are radiated from following the detonation of an explosive charge buried in a block. In order to simulate full scale blasting operations at sea, small explosive charge of 1.8g PETN was buried in a concrete block and detonated under water. Information concerning the test set-up, instrumentation, type of explosives used, scaling factor and measurement of pressure is briefly described. The paper also presents analysis of the test results in the form of FFT’s and Transfer functions and details of …

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Control Of Seismic Response Of Structures, Chris P. Pantelides Mar 1991

Control Of Seismic Response Of Structures, Chris P. Pantelides

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

Safety requirements for structures built in seismic regions have led to techniques for absorbing the energy induced to these structures by earthquakes. Passive isolation systems such as base isolators are suitable for low-rise structures but they provide only a partial solution to the problem. This paper presents three active control techniques for reducing the dynamic response of machine supporting foundations. The concept of active control is discussed and various control strategies are presented. The active tendon system (ATS), active mass damper (AMD), and active base control (ABC) mechanisms are examined. Both optimal and non-optimal control algorithms are described and numerical …

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Ground Vibration Isolated By Silo And Pile Barriers, Xian-Jian Yang Mar 1991

Ground Vibration Isolated By Silo And Pile Barriers, Xian-Jian Yang

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

Based on the model, field test and theory research, this paper puts forward the design method of ground vibration isolated by silo and pita barriers, the practical engineering calculation and the remained problems in this respect. It is pointed out that although the diameter of pile is much smaller than that L/δ shielded wave length (Woods 1978), the ground wave motion can be effectively shielded so long as the proper pile distance is to be selected. This makes it possible that the silo and pile (as well as the pile of other form and material) barriers can be used in …

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Ground Vibration Isolation Using Gas Cushions, K. Rainer Massarsch Mar 1991

Ground Vibration Isolation Using Gas Cushions, K. Rainer Massarsch

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

A new ground vibration isolation method is described, which uses inflated, flexible cushions. The isolation cushions have therefore a low impedance and act as vibration reflectors in the ground. Practical aspects, such as the production of the gas cushions screen, the installation method and the gas-tightness of the gas cushions are discussed. The screen can be installed to great depth, using the well-proven slurry trench technique. After installation, the trench is filled with a self-hardening cement-bentonite grout, which creates a plastic, water-tight protection layer around the cushions and assures the long term stability of the screen. The gas cushion screen …

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Integrated Analysis Of Turbomachinery Frame-Foundation-Soil Interaction, Madhira R. Madhav, N. G. R. Iyengar, S. Kathiroli Mar 1991

Integrated Analysis Of Turbomachinery Frame-Foundation-Soil Interaction, Madhira R. Madhav, N. G. R. Iyengar, S. Kathiroli

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

For the smooth functioning of turbomachines, the design of the rotor, the bearings, the supporting structure, and the foundation should be carried out as an integrated system. The frequency domain method in conjunction with FEM is chosen for the analysis. The modified influence matrix boundary condition method is applied to reduce the number of equations to be solved. Results for 4 idealized cases are compared. It is shown that the interaction effects are significant in the lowest frequency domain.

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On Predictions And Performance Of Machine Foundations, George M. S. Manyando, Shamsher Prakash Mar 1991

On Predictions And Performance Of Machine Foundations, George M. S. Manyando, Shamsher Prakash

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

A model for predicting the amplitude versus frequency response for surface footings under vibrations is presented. The model considers the effects of soil nonlinearity and confining pressures on soil modulus and has been verified by comparing model predictions with performance field tests. The elastic half space analog solutions have been used to develop a computer program for this prediction model (Manyando, 1990). Soil nonlinearity has been accounted for by incorporating an iterative procedure in the computer program. The computer program was used to predict the footing response in vertical, torsional and coupled rocking and sliding vibrations. Predicted resonant amplitudes, resonant …

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Pile Driving Criteria For Construction Near An Historic Dam, L. P. Jedele Mar 1991

Pile Driving Criteria For Construction Near An Historic Dam, L. P. Jedele

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

The construction of a new road included a bridge crossing a river. The location of the bridge crossing was about 300 feet (91.5 meters) downstream from an historic dam. Prior to construction, concerns were raised about vibrations which might be generated from construction activities, especially pile driving for the new bridge abutments, and their potential effect on the integrity of the dam. As a result, a vibration study was conducted on the dam, prior to construction, to assess the vibrations generated from normal operation of the dam and from a simulated pile driving operation. Based on the simulated pile driving …

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Simple Design Methods For Vibration Isolation By Wave Barriers, Tahmeed M. Ai-Hussaini, Shahid Ahmad Mar 1991

Simple Design Methods For Vibration Isolation By Wave Barriers, Tahmeed M. Ai-Hussaini, Shahid Ahmad

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

Rectangular wave barriers (open or infilled trenches) are frequently used in engineering practice to reduce the ground vibrations caused by propagating surface (Rayleigh) waves of relatively small wave lengths. This paper presents models involving simple algebraic formulas for the design of rectangular wave barriers in homogeneous soil deposits. Both vertical and horizontal ground vibrations are considered. An extensive parametric investigation was conducted using a direct boundary element method algorithm. Simple models based on the key dimensionless parameters that control the vibration screening effectiveness were then developed. The utility of such models is established through comparisons with rigorous numerical solutions and …

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The Optimization Principles Of The System "Mass Blast-Protected Structure", Yugeni Borisov, Boris Pishkin Mar 1991

The Optimization Principles Of The System "Mass Blast-Protected Structure", Yugeni Borisov, Boris Pishkin

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

The real work is ideological result of the investigations, which have been carried out for 25 years, on structural dynamics under the seismo-explosive loads, induced by industrial and experimental blasts, simulating natural earthquakes, and on the optimization parameters of drill explosive works in the mining quarrels.

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Turbogenerator Foundation Analysis Under Wide-Range (Seismic In Particular) Excitation, Igor Andrianov, Vladimir Sedin Mar 1991

Turbogenerator Foundation Analysis Under Wide-Range (Seismic In Particular) Excitation, Igor Andrianov, Vladimir Sedin

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

Dynamics of turbogenerator foundation under wide-range (seismic in particular) excitation is being investigated. It is rather simple to get a solution for low- and high- frequency vibrations in case of a ribbed plate resting on elastic subgrade. As for practical purposes, it is a solution for intermediate parameter values that is of solution. It is shown here that the difficulties could be overcome by two-point fade-approximant method.

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Earthquake Ground Motions At Soft Soil Sites, I. M. Idriss Mar 1991

Earthquake Ground Motions At Soft Soil Sites, I. M. Idriss

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

No abstract provided.

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Ground Failure During Loma Prieta Eq - Downtown Santa Cruz, Alan Kropp, Michael Thomas Mar 1991

Ground Failure During Loma Prieta Eq - Downtown Santa Cruz, Alan Kropp, Michael Thomas

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

Ground failure occurred in numerous locations in the downtown Santa Cruz area during the Lorna Prieta Earthquake. These failures included liquefaction, lateral spreading and lurch cracking. Mapping of many of these features was made within three days of the earthquake, before heavy rains obscured much of the surface evidence. Data from a United States Geological Survey study of liquefaction potential in Santa Cruz has been examined. In addition, subsurface information has been collected from several downtown subsurface exploration studies. A comparison has been made between areas where ground failure was predicted and where it occurred during the Lorna Prieta Earthquake. …

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Liquefaction Of Soils In The 1989 Loma Prieta Earthquake, Raymond B. Seed, Michael F. Riemer, Stephen E. Dickenson Mar 1991

Liquefaction Of Soils In The 1989 Loma Prieta Earthquake, Raymond B. Seed, Michael F. Riemer, Stephen E. Dickenson

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

The Loma Prieta Earthquake of October 17, 1989 was the most costly single natural disaster in U.S. history, resulting in losses of $7 to $9 billion, and claiming 63 lives. These damages were concentrated mainly at a number of distinct sites comprising a relatively small fraction of the affected region, as local site conditions and related geotechnical factors exerted a major influence on damage patterns and loss of life in this catastrophic event. This paper discusses one of these geotechnical factors, the widespread occurrence of soil liquefaction during the earthquake, as well as the associated damages and the resulting lessons …

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Performance Of Concrete Faced Earthdam To Loma Prieta Earthquake, Sukhmander Singh, Nick Pal Mar 1991

Performance Of Concrete Faced Earthdam To Loma Prieta Earthquake, Sukhmander Singh, Nick Pal

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

As a result of the shaking from the Loma Prieta Earthquake of 1989, the concrete lining of an earth embankment suffered cracking at numerous locations on its upstream side and developed in its bed lining, crater-like pot-holes ranging in size up to 10 ft. in diameter. Field investigation and preliminary studies indicated the differential dynamic vibrations of the earth embankment and the concrete lining to be the cause of the cracking, and the liquefaction of the underlying stratum below the bottom of the reservoir to be the cause of the pot-holes formed as a result of the pore pressure bursting …

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Site Stratigraphy And Its Effects On Soil Amplification In The Greater Oakland Area During The October 17, 1989 Loma Prieta Earthquake, J. David Rogers Mar 1991

Site Stratigraphy And Its Effects On Soil Amplification In The Greater Oakland Area During The October 17, 1989 Loma Prieta Earthquake, J. David Rogers

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

No abstract provided.

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Source, Path And Site Effects On Loma Prieta Strong Motions, P. G. Somerville, N. F. Smith Mar 1991

Source, Path And Site Effects On Loma Prieta Strong Motions, P. G. Somerville, N. F. Smith

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

The amplitudes of strong ground motions from the Loma Prieta earthquake recorded in the San Francisco and Oakland areas exceeded the levels predicted by standard empirical attenuation relations. Preliminary analysis of accelerograms having known trigger times suggests that the elevation of ground motion amplitudes in the distance range of approximately 40 to 100 km was due to critical reflections from the base of the crust. These reflections were large and occurred at relatively close range because of the deep focal depth of the earthquake and the strong velocity gradient at the base of the crust, and were enhanced by rupture …

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Two Sequences Of Fine Grained Soil Liquefaction At Soda Lake, Pajaro River Valley, Santa Cruz County, California, J. David Rogers, C. J. Wills, M. W. Manson Mar 1991

Two Sequences Of Fine Grained Soil Liquefaction At Soda Lake, Pajaro River Valley, Santa Cruz County, California, J. David Rogers, C. J. Wills, M. W. Manson

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

Soda Lake was originally a natural lake in an abandoned meander bend of the Pajaro River. The San Andreas Fault zone lies 350 meters southwest of the lake, on a northwesterly trend. The natural lake was diked with embankments approximately 3 to 6 meters high on its 'southern and eastern sides in 1968 for use as a tailings pond. Fine waste material from Granite Rock Company's Wilson quarry, located just across the river and approximately 0.5 kilometers west of the lake, was periodically slurried by pipeline over to Soda Lake and thence hydraulically deposited from 1968 to the present. During …

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Ground Motion Characteristics Of The San Francisco Bay Area Detected By Microtremor Measurements, T. Ohmachi, Y. Nakamura, T. Toshinawa Mar 1991

Ground Motion Characteristics Of The San Francisco Bay Area Detected By Microtremor Measurements, T. Ohmachi, Y. Nakamura, T. Toshinawa

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

Microtremor measurement was done mainly in the damaged areas in San Francisco and Oakland after the 1989 Loma Prieta earthquake. The observation areas were (1) the Marina District, (2) Cypress Street, (3) the Embarcadero, and (4) South of Market District. Predominant frequency (Fp) and amplification factor (Ap) obtained from a spectral ratio between horizontal and vertical components were evaluated for each observation cite. Difference in the degree of damage in the areas (1) and (4) was coincident with difference in Ap and Fp. Significant difference could not be found in Ap and Fp between the areas (2) and (3).

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Liquefaction And Surface Settlement In The Marina District, D. Rosidi, W. B. Wigginton Mar 1991

Liquefaction And Surface Settlement In The Marina District, D. Rosidi, W. B. Wigginton

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

This paper evaluates the liquefaction potential of sands within the Marina District. Three types of underlying potentially liquefiable soil deposits are studied: (A) Hydraulic fill, (B) Artificial fill, and (C) Strawberry Island and other modern beach deposits. A liquefaction analysis for each of these deposits is conducted. It is suggested that a Peak Ground Acceleration (PGA) of approximately 0.1g is needed in the Marina District to initiate liquefaction. Relations between PGA and thickness of liquefiable soil, as well as potential surface settlement are presented. These relationships are useful for the study of expected performance of the Marina District in future …

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Sanitary Landfill Performance During The Loma Prieta Earthquake, Dennis Buranek, Sangeeta Prasad Mar 1991

Sanitary Landfill Performance During The Loma Prieta Earthquake, Dennis Buranek, Sangeeta Prasad

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

The October 17, 1989, Loma Prieta earthquake subjected a number of solid waste or sanitary landfills to significant shaking. The performance of sanitary landfills during large earthquakes is of great interest to the public, state and federal agencies, and the landfill owners. The observed performance of six sanitary landfills located within the Lorna Prieta earthquake damage zone is compared with the performance predicted by a commonly used deformation analysis technique. The six landfills were inspected immediately after the October 17, 1989, magnitude 7.1 earthquake. Damage and evidence of slope movement, or lack thereof, was recorded. The mean peak ground accelerations …

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Site Effects In The Loma Prieta Earthquake And Comparison With An Earthquake Intensity Prediction Method, Hatukazu Mizuno, Akio Abe Mar 1991

Site Effects In The Loma Prieta Earthquake And Comparison With An Earthquake Intensity Prediction Method, Hatukazu Mizuno, Akio Abe

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

Strong motion records of the Loma Prieta Earthquake of October, 17, 1989 have been analyzed in comparison with epicentral distances and types of soil deposits, and site effects and attenuation relations have been studied. Site effects are significantly recognized in the earthquake, as usually found in Japanese earthquakes. And validity of the U.S. seismic intensity prediction method that Association of Bay Area Governments (ABAG) adopted to prepare some earthquake preparedness maps has been examined on the basis of the Loma Prieta Earthquake data. Finally, soil damping of San Francisco Bay Area has been evaluated from the strong motion records.

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General Report Session 5: Soil-Structure Interaction Under Dynamic Loading, E. Kausel, J. Roesset, A. H. Hadjian, J. Bielak, G. R. Martin Mar 1991

General Report Session 5: Soil-Structure Interaction Under Dynamic Loading, E. Kausel, J. Roesset, A. H. Hadjian, J. Bielak, G. R. Martin

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

No abstract provided.

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Testing Of Stressed State In The Structure-Base System Under Non-Stationary Dynamic Effects, Vyacheslav K. Musaev Mar 1991

Testing Of Stressed State In The Structure-Base System Under Non-Stationary Dynamic Effects, Vyacheslav K. Musaev

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

Some aspects of practical realization of the finite element method (FEM) are considered for solving a two-dimensional (plane) dynamic problem of the theory of elasticity and plasticity. The results of the numerical solution of some problems for dynamic effects are presented. The comparison with the results of other methods is made.

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Validation Of A Piles Dynamic Analysis Computer Code Through In Situ Tests, R. Bonaz, A. Pecker, T. Duroy, M. Ralljaona, J. P. Touret Mar 1991

Validation Of A Piles Dynamic Analysis Computer Code Through In Situ Tests, R. Bonaz, A. Pecker, T. Duroy, M. Ralljaona, J. P. Touret

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

In order to qualify the CLAPIFOU code, which computes the dynamic response of a pile foundation subjected to earthquake or harmonic forces, a test campaign was carried out on piles, to full scale, on pile groups of 2 x 1 piles and 2 x 3 piles on the Plancoet site. The purpose of the study is to compare the results of the experiments and the digital simulations with the computer code. The comparison is good but confirms the need for a good knowledge of the soil's characteristics.

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Aspects Of Seismic Analysis And Design Of Rockfill Dams, George Gazetas, Panos Dakoulas Mar 1991

Aspects Of Seismic Analysis And Design Of Rockfill Dams, George Gazetas, Panos Dakoulas

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

Theoretical methods for estimating the dynamic response and predicting the performance of modern rockfill dams subjected to strong earthquake shaking are reviewed. The focus is on methods accounting for nonlinear material behavior, for 3-Dimensional canyon geometry, and asynchronous base excitation. It is shown that both strong nonlinearities and lack of coherence in the seismic excitation tend to reduce the magnitude of the deleterious "whip-lash" effect computed for tall dams built in rigid-wall narrow canyons. Particular emphasis is accorded to Concrete-Faced Rockfill dams and a case study involving an actually designed dam in a narrow canyon points to some potential problems …

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