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1991

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Articles 931 - 960 of 1363

Full-Text Articles in Engineering

Liquefaction Analysis For Rubber Dam And Review Of Case Histories Of Liquefaction Of Gravels, Julio E. Valera, Jon Y. Kaneshiro Mar 1991

Liquefaction Analysis For Rubber Dam And Review Of Case Histories Of Liquefaction Of Gravels, Julio E. Valera, Jon Y. Kaneshiro

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

A geotechnical investigation for the design and construction of an air-inflated rubber dam (for ground-water recharge) was performed, including evaluation of the liquefaction potential of the dam's foundation. The dam, about 300 feet long and 13 feet high when fully inflated is located along Alameda Creek at the upper part of the alluvial fan near Fremont, California. The sediments at the site are generally sandy gravels and gravelly sands. In order to fully investigate the liquefaction potential of the gravelly soils, the soils themselves were studied, and case histories involving similar conditions were reviewed. These case histories indicate that, in …

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Liquefaction Analysis Of Sands: Some Interpretation Of Seed's KΑ (Sloping Ground) And KΣ (Depth) Correction Factors Using Steady State Concept, V. S. Pillai Mar 1991

Liquefaction Analysis Of Sands: Some Interpretation Of Seed's KΑ (Sloping Ground) And KΣ (Depth) Correction Factors Using Steady State Concept, V. S. Pillai

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

Seed's Liquefaction Assessment Chart (SLAC) correlates the corrected SPT blow count (N1)60 to the cyclic stress ratio required to cause liquefaction for free field level ground conditions. However, the cyclic stress ratio or the liquefaction resistance of a soil under sloping ground (initial static shear) and at depth (high confining pressure) would be significantly different from that derived from the SLAC. To correct the liquefaction resistance for the initial static shear and confining pressure, factors Kα and Kσ are used respectively. The factors have significant influence on the evaluation of liquefaction resistance against earthquake loading …

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Liquefaction Criterion For Sand Deposits During Earthquake, Wu Yuejin Mar 1991

Liquefaction Criterion For Sand Deposits During Earthquake, Wu Yuejin

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

In this paper, the cyclic stress conditions for the liquefaction of sand samples and deposits are presented. The liquefaction criterion for sand deposits during earthquake is given. Finally the criterion is discussed from two aspects.

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Liquefaction During Two Moderate-Recent Earthquakes In India, Pramod N. Agrawal Mar 1991

Liquefaction During Two Moderate-Recent Earthquakes In India, Pramod N. Agrawal

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

The observations of liquefaction during the Cachar earthquake of N.E. India in December 31, 1984 (M=5.6) and the Great Nicobar earthquake of January 20, 1982 (M=6.3) have been reported. These observation, at short epicentral distances where duration of sustained motion was insufficient to postulate induced dynamic increase in pore water pressure, have been explained as quick-sand phenomena due to disturbance of soil structure under the influence of impulsive force associated with rupture at source. The proposed physical mechanism also explains well the bending of ceiling fan blades in Cachar earthquake and upthrow of objects during earthquakes in general. The discussion …

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Liquefaction Induced Permanent Ground Displacement In Niigata City, Masanori Hamada, Kazue Wakamatsu, Susumu Yasuda Mar 1991

Liquefaction Induced Permanent Ground Displacement In Niigata City, Masanori Hamada, Kazue Wakamatsu, Susumu Yasuda

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

Permanent ground displacement resulting from the 1964 Niigata Earthquake were studied based on pre- and post-earthquake aerial surveys. In the area along the Shinano River and the Tsusen River, extensive large ground displacements up to about 10 m occurred towards the river, though the ground was almost flat. To ascertain the mechanism of such large ground displacement, several detailed soil investigations were conducted. And it was clarified that the gradient of the ground surface, the gradient of the bottom of the liquefied layer and the thickness of the liquefied layer were main factors affecting to the such large ground displacement.

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Liquefaction Potential Evaluation Based On Rayleigh Wave Investigation And Its Comparison With Field Behavior, Kohji Tokimatsu, Shuji Tamura, Shinichi Kuwayama Mar 1991

Liquefaction Potential Evaluation Based On Rayleigh Wave Investigation And Its Comparison With Field Behavior, Kohji Tokimatsu, Shuji Tamura, Shinichi Kuwayama

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

A simplified method is presented for evaluating liquefaction potential of sand deposits using shear wave velocity. Effectiveness of the proposed method is evaluated through field tests at 17 sites in Niigata city where field performance during the 1964 Niigata earthquake is known. A modified version of steady state Rayleigh wave method is used in which the amplitude ratio between vertical and horizontal ground surface motions can be measured in addition to the phase velocity. Based on the measured phase velocity vs. wavelength relationship, shear wave velocity profile is determined using an inverse analysis. The liquefaction potential of each site is …

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Liquefaction Potential Prediction By Multiple Stage Multifactorial Evaluation, Limin Zhang, Ting Hu Mar 1991

Liquefaction Potential Prediction By Multiple Stage Multifactorial Evaluation, Limin Zhang, Ting Hu

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

Factors affecting liquefaction are analyzed. Qualitative factors along with liquefaction itself are conceived to be of fuzziness the common methods cannot deal with. A new method – the Multiple-Stage Multifactorial Evaluation is introduced to evaluate the liquefaction potential of sand which can take into account not only the factors considered by the common methods but also these qualitative factors which otherwise cannot be considered by the explicit mathematic evaluation methods and can treat each factor according to its importance to liquefaction. Tests with the method show a higher correct evaluation rate over other methods. Conclusion is drawn about the liquefaction …

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Session 3: Opening Remarks, G. Castro Mar 1991

Session 3: Opening Remarks, G. Castro

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

No abstract provided.

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Pore Pressure Response During 1986 Lotung Earthquakes, C. K. Shen, Zhiliang Wang, X. S. Li Mar 1991

Pore Pressure Response During 1986 Lotung Earthquakes, C. K. Shen, Zhiliang Wang, X. S. Li

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

In 1986, two significant earthquake events in Lotung, Taiwan were recorded with both acceleration and pore water pressure traces at different depths below the ground surface. One event (M=6.2) was recorded on July 30th with an epcientral distance of 6km, and the other (M=7.0) was recorded on November 14th with an epicentral distance of about 80 km from the site. To analyze the recorded data, a finite element procedure was developed. The procedure incorporates a newly developed bounding surface hypoplasticity model for granular soils and can handle multidirectional input motions. The finite element procedure takes into consideration pore water pressure …

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Prediction Of Field Sand Liquefaction Caused By Earthquake By Optimum Seeking Method, Du Jian, Zhang Lianyang Mar 1991

Prediction Of Field Sand Liquefaction Caused By Earthquake By Optimum Seeking Method, Du Jian, Zhang Lianyang

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

There are many uncertain factors influencing the field sand liquefaction induced by earthquake, therefore, the predictions of available methods are usually unsatisfactory. In this paper, a new way is developed, i.e., according to the available field sand liquefaction data, the influencing factors are optimized by optimum seeking method, then the prediction is made on the optimized results. By this method, 20 field cases are predicted and the correct rate is 95%. It proves that the suggested method is effective and feasible.

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Prediction Of Liquefaction Behaviour Of Cohesionless Soils, Nakul Dev, Shenbaga R. Kaniraj Mar 1991

Prediction Of Liquefaction Behaviour Of Cohesionless Soils, Nakul Dev, Shenbaga R. Kaniraj

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

In order to mitigate earthquake effects occurring because of soil liquefaction, it is essential that the characteristics of soil deposits prone to liquefaction be reliably assessed. The present paper is an attempt in this direction. Liquefaction behaviour of five sands of different gradation characteristics is evaluated under cyclic simple shear conditions and the results have been used to predict the behaviour of Badarpur sand. Fineness Modulus, and a grain size and gradation factor have been used to predict the cyclic strength. The predicted behaviour is then verified by carrying out simple shear tests on Badarpur sand. As the predicted strength …

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Preliminary Research In Predicting Liquefaction Potential Of Saturated Soil Using Vs, Qc, Chang Hong Mar 1991

Preliminary Research In Predicting Liquefaction Potential Of Saturated Soil Using Vs, Qc, Chang Hong

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

In the paper, first describes the condition of the testing ground, then the circumstances of test (pressed wave velocity test & static cone penetration test, or vs & SCPT) is presented, i.e., the improvement of SCPT equipment make the test (Vs & SCPT) be in progress simultaneously, meanwhile, the SPT is conducted so that relations are found among the testing data. The results of tests are shown in this paper, the relative curves of sandy soil and sandy loam (Vs & N, qc & N) are gained respectively by way of analysing the test data, and experiential formulas of the …

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Sand Liquefaction With Initial Pore Pressures, Hong Xia Mar 1991

Sand Liquefaction With Initial Pore Pressures, Hong Xia

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

Cyclic triaxial tests are conducted on saturated sand samples with different values of initial pore pressures existed throughout the whole process of tests. It is found that the presence of such initial pore pressures (or static hydraulic pressures) tends to increase the liquefaction resistance of the sand samples. The effects of the degrees of saturation are also investigated by conducting another four sets of the cyclic triaxial tests on sand samples with different levels of saturation, since the degree of saturation is a very closely related factor which could be changed by the presence of the initial pore pressures. The …

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Semi-Analytical Iteration Algorithm Of Seismic Pore Pressure, Zhang Jianmin, Xie Dingyi Mar 1991

Semi-Analytical Iteration Algorithm Of Seismic Pore Pressure, Zhang Jianmin, Xie Dingyi

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

In this paper a semi-analytical iteration method for predicting the seismic pore-water pressure generation and dissipation in saturated sand layers is suggested. The fundamental formulae including three general analytical solutions under the condition of the 1-D, 2-D, and 3-D dissipation and the calculation principle are briefly presented, and then the suggested method is used in predicting the generation and dissipation of seismic pore water pressure in the 1-D saturated sand layers as an example. The suggested method provides the possibility to consider at a certain extent the change characteristics in permeability and volumetric strain of sand during the seismic action …

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Settlement Calculations Of Clay Layers Induced By Earthquake, Hiroshi Matsuda, Eiichi Hoshiyama, Sukeo Ōhara Mar 1991

Settlement Calculations Of Clay Layers Induced By Earthquake, Hiroshi Matsuda, Eiichi Hoshiyama, Sukeo Ōhara

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

A procedure to calculate the seismic settlement of clayey layers is developed based on the strain-controlled cyclic simple shear test results. By using this procedure the seismic ground settlements are estimated and also the results are compared with the observed ones. In the calculations, six types of accelerogram are used. As a result of estimations, following conclusions are obtained. (1) In the case of a horizontal soil layer of 5 m in height, the settlements are in the range from 3 to 6 cm for a maximum acceleration of about 340 gal. (2) In the case of clay deposits in …

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The Characteristics Of Residual Strength Of Silt Under Liquefaction Conditions, H.-C. Fei, F. Lu Mar 1991

The Characteristics Of Residual Strength Of Silt Under Liquefaction Conditions, H.-C. Fei, F. Lu

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

Silt soil is defined as a soil whose fine particles (D50 < 0.005mm) content is from 3% to 15%. The Tangshan earthquake of 1976 had a magnitude of 7.8 and caused the liquefaction of silt soil in large areas in Tianjin City. The seismic intensity at Tianjin was 8° in downtown. Currently the same criterion for initial liquefaction is applied to silt and sand, e.g., the development of pore pressure, u, equal to the effective confining pressure σ0'. However, in silt residual strength still exists because of cohesion due to the finest of the particles even when u = σ0' due to shaking. The authors employed a superimposed ring shear device to study the characteristics of residual shear strength of silts with different fine particle contents and with various pore pressure ratios, u/ σv' under both dynamic and static loads.

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Utilization Of Cone Penetration Test To Evaluate Liquefaction Potential Of Soils, Teparaksa Wanchai Mar 1991

Utilization Of Cone Penetration Test To Evaluate Liquefaction Potential Of Soils, Teparaksa Wanchai

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

A new practical method for evaluation of soil liquefaction by using the Cone Penetration Test (CPT) was proposed. The critical normalized cone resistance, (qcl)cr was presented in terms of cyclic stress ratio, τ/σ0' , and mean grain size of soils, D50. Based on our proposed CPT-based liquefaction assessing correlation, we presented the typical examples of the use and application of CPT to assess liquefaction potential of past earthquake as well as to verify the effectiveness of soil improvement counterrneasured to increase liquefaction resistance of soil.

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Vibrations Of An Inhomogeneous Layer, Hasan Engin, M. Ertac Erguven Mar 1991

Vibrations Of An Inhomogeneous Layer, Hasan Engin, M. Ertac Erguven

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

In this study, we have investigated vibrations of an inhomogeneous layer which is forced along its bottom. The shear modulus of the layer varies with depth. Considering the layer thickness is constant and the forcing displacement at the bottom is horizontal, shear vibrations will be studied. The solution of the governing equation has been carried out by using Bessel functions including unknown parameter q. Frequencies which make the amplitude of vibrations infinite are called natural frequencies of the layer. Variational of the natural frequencies and the shape of the shearing waves along the thickness of the layer have been investigated …

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Displacement Based Design Of Retaining Walls, Raj Siddharthan, Prakash K. Gowda, Gary M. Norris Mar 1991

Displacement Based Design Of Retaining Walls, Raj Siddharthan, Prakash K. Gowda, Gary M. Norris

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

A relatively simple rigid plastic model to study deformation behavior of rigid retaining wall is outlined. Both sliding and tilting modes of deformation are included. The study clearly reveals that wall movement caused by tilting can be substantial. But for high values of foundation soil friction angle, the tilting component of deformation can be omitted. Since the wall movement is affected by the characteristics (strength and frequency) of the excitation history, a number of excitation histories should be considered in retaining wall designs.

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Dynamic Earth Pressure Distribution Behind Retaining Walls, D. M. Dewaikar Mar 1991

Dynamic Earth Pressure Distribution Behind Retaining Walls, D. M. Dewaikar

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

The point of application of dynamic active thrust and its distribution are computed using the method of slices and criterion of maximization of overturning moment of the active thrust. The computations show that point of application of the dynamic thrust is significantly influenced by such factors as wall friction and acceleration coefficients. Horizontal accelerations coupled with positive vertical accelerations (acting downwards) have the effect of moving the point of application closer to the wall base. The combination of horizontal acceleration with negative vertical acceleration produces exactly the reverse effect and generates more overturning moments even though the magnitude of corresponding …

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Effective Stress Analysis Of A Sheet Pile Quaywall, Susumu Lai, Tomohiro Kameoka Mar 1991

Effective Stress Analysis Of A Sheet Pile Quaywall, Susumu Lai, Tomohiro Kameoka

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

In 1983, Nihonkai Chubu Earthquake of magnitude 7.7 hit northern part of Japan. The earthquake caused damage to quaywalls at Akita Port located about 100 km from the epicenter. The damage was associated with the liquefaction of backfill sand. In order to analyze the mechanism of the damage, soils are taken from the site for laboratory tests. The record of the earthquake motion is digitized. Based on these investigations, a two dimensional effective stress analysis is conducted. The model used in this study consists of a multiple virtual simple shear mechanisms oriented in arbitrary directions. The results of the effective …

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Seismic Design Of Rigid Underground Walls In New England, Cetin Soydemir Mar 1991

Seismic Design Of Rigid Underground Walls In New England, Cetin Soydemir

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

The Mononobe-Okabe equation is still widely used in design practice to estimate earthquake induced soil pressures against earth retaining structures without differentiation of the lateral yielding or non-yielding character of the structure. Where these structures are rigid and non-yielding because of structural restraints (e.g., basement walls, bridge abutments, underground transportation, hydraulic and sanitary structures) the use of Mononobe-Okabe equation would not be appropriate and would be generally unsafe. Alternate design recommendations are proposed, based on the results of recent analytical and experimental studies by other researchers, for a nominal design earthquake expected to be representative of the New England seismicity.

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Seismic Earth Pressures Against Structures With Restrained Displacements, P. Ortigosa, H. Musante Mar 1991

Seismic Earth Pressures Against Structures With Restrained Displacements, P. Ortigosa, H. Musante

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

A simplified kinematic method to compute seismic earth pressures against structures with restrained horizontal displacements is described. The retaining structure has a linear elastic behavior and the retained soil is considered linear as well as a nonlinear material. Seismic pressures for different maximum free field accelerations were obtained by applying free field horizontal displacements at the base of the interaction springs connecting the soil and the retaining structure. For perfectly rigid structures without horizontal displacements and linear retained materials, seismic pressures obtained with the simplified kinematic method are compared with those obtained using elastic models; for nonlinear retained soils comparisons …

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Stability Of Fiber Reinforced Sand Retaining Walls, Masami Fukuoka, Kakuhiro Nakayama, Shun-Ichi Lhara, Kiyohiro Okedoi, Ken-Ichirou Ozaki Mar 1991

Stability Of Fiber Reinforced Sand Retaining Walls, Masami Fukuoka, Kakuhiro Nakayama, Shun-Ichi Lhara, Kiyohiro Okedoi, Ken-Ichirou Ozaki

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

A ten meter high retaining wall made by sands reinforced with continuous fibers was constructed in 1988. Thickness of the retaining wall was 1 mat the top and 2.5 m at the bottom, and the slope was 63° at the face and 71° at the back. Earth pressure acting on the wall, displacements of the face, settlements of the fill and acceleration of the retaining wall were measured. During the construction, around the third height of the wall was displaced 15 cm in a forward direction. At the time of an earthquake, the values of the maximum horizontal acceleration at …

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Study And Design Of Earth Reinforced Structures Under Dynamic Efforts, Ammar Dhouib, Grant Knochenmus Mar 1991

Study And Design Of Earth Reinforced Structures Under Dynamic Efforts, Ammar Dhouib, Grant Knochenmus

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

This paper aims at giving a synthesis of recent design methods of earth reinforced structures submitted to dynamic actions. In the first instance, we intend to tackle a comparative study on scaled - down models and on real works in reinforced earth. This study is led by the finite elements method. Secondly, we propose a simple method to design reinforced earth structures.

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A Hybrid Model For Soil-Foundation Compliance, Chin-Hsu Lin, Teresa M. Adams Mar 1991

A Hybrid Model For Soil-Foundation Compliance, Chin-Hsu Lin, Teresa M. Adams

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

This paper describes a hybrid method that may be used to model the dynamic responses of multiple rectangular foundations resting on a homogeneous, viscoelastic stratum and excited by harmonic waves. The hybrid analysis described in this paper combines the dynamic stiffness and finite element methods. The method uses equivalent area disk loads for Green's functions at the soil surface. The dynamic stiffness method is used to obtain the stiffness matrix of the soil medium and the finite element method is used to obtain the stiffness matrix of surface foundations. The stiffness of the entire soil-structure system can be obtained using …

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A Hybrid Modeling Of Soil Structure Interaction Problems, Celso Romanel, Tribikram Kundu Mar 1991

A Hybrid Modeling Of Soil Structure Interaction Problems, Celso Romanel, Tribikram Kundu

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

A hybrid method is proposed in this research for dynamic soil-structure interaction analysis of embedded structures within a multilayered elastic half-space. A near field region, containing the structure and a portion of soil surrounding it, is modeled by finite elements while the far field formulation is obtained through the classical wave propagation theory based on the assumption that the actual scattered wave fields can be represented by a set of line sources located at a depth corresponding to the center of mass of the structure under investigation. Traction reciprocity between the two regions is satisfied exactly while displacement continuity across …

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Analysis Of Pile-Soil Dynamic Interaction By Combination Of Bem And Fem, Shiming Wu, Yuanqiang Cai, Yunmin Chen, Longzhu Chen Mar 1991

Analysis Of Pile-Soil Dynamic Interaction By Combination Of Bem And Fem, Shiming Wu, Yuanqiang Cai, Yunmin Chen, Longzhu Chen

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

A hybrid method, in which soil media is modeled by 3-D boundary elements and the pile by 1-D finite elements, for an analysis of dynamic pile-soil interaction is investigated. A new series of equations and an efficient method to deal with singularity of integrals are presented. Several effects including pile length, stiffness of the pile and surrounding soil on dynamic response are studied. Finally, the characteristics of impaired and intact piles are investigated and compared; and some case studies are presented.

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Behaviour Of Cyclically Loaded Model Piles In Soft Clay, R. D. Purkayastha, S. Dey Mar 1991

Behaviour Of Cyclically Loaded Model Piles In Soft Clay, R. D. Purkayastha, S. Dey

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

Instability studies on offshore piles has been carried out to a very limited extent. Cyclic loading resulting from wave action is a very common phenomenon for such piles. Continuous cycling {both vertical and lateral) presumably leads to substantial degradation in pile-soil response, the ultimate result of which could be disastrous. Over the last decade and a half, some work has been done to study the pile-soil interaction behaviour under repeated cyclic loading. This paper aims to highlight and discuss the salient features and the important observations of extensive model tests on piles subjected to vertical cyclic load. The degradation of …

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Dynamic Response Of Flexible Foundations On Multilayered Medium, Wang Fuming Mar 1991

Dynamic Response Of Flexible Foundations On Multilayered Medium, Wang Fuming

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

The dynamic response of flexible strip-foundations placed on a viscoelastic multi-layered medium under conditions of plane strain and subjected to harmonic excitation is studied in this paper. A semi-analytic model is developed to determine the dynamic flexibility matrix of the medium, and the spline finite element method is employed to treat the foundation. The two methods are appropriately combined through equilibrium and compatibility considerations at the soil-foundation interface. Numerical results describing the influence of the non-homogeneity of the soil medium on the compliance are presented, and the effects of the relative stiffness Kr on the foundation response are briefly discussed.

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