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Mechanical Characterization Of The Threshold Strain In Sand Liquefaction, A. Kaddouri Mar 1991

Mechanical Characterization Of The Threshold Strain In Sand Liquefaction, A. Kaddouri

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

DOBRY et al, YOUD have shown the existence of a shearing threshold strain in the vicinity of 10-4 which guides the occurrence of liquefaction. With tests on glass beads and sand from the Algiers bay, using a proper measuring system, we were able to arrive at a better resolution of this threshold and to the determination of its mechanical signification.

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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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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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Slides Of River Banks Concerning Lateral Spread Of Liquefaction, Huishan Liu, Chengchuen Wang, Lunian Wong Mar 1991

Slides Of River Banks Concerning Lateral Spread Of Liquefaction, Huishan Liu, Chengchuen Wang, Lunian Wong

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

In this paper 19 cases of river bank slides concerning lateral spread of liquefaction are summarized, some of them are discussed in detail. One of the cases was the lateral spread of liquefied sands by Liao River during Heichen Earthquake (1975, M=7.3). The width of sliding zone in direction perpendicular to the flow was around 500-600m. The second case was about an industrial area in Tianjing, one of the largest cities in China. The land sliding along a silted old course made many buildings cracked and even collapsed. The third case was on liquefaction along Dou River and Luan River. …

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Some Key Problems In Calculating Seismic Pore Water Pressure, Zhang Jianmin, Xie Dingyi Mar 1991

Some Key Problems In Calculating Seismic Pore Water Pressure, Zhang Jianmin, Xie Dingyi

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

The problems of selecting a reasonable generation model and a reasonable generation-dissipation model of pore water pressure and determining the coefficient of permeability and the coefficient of volumetric strain in the course of pore water pressure generation-dissipation are crucial in the calculation of seismic pore water pressure. These problems are investigated theoretically and experimentally in this paper based on the concepts of transient pore pressure with connection to the practically possible calculating conditions, so as to improve the reliability of the current seismic effective stress analysing method.

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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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Twice Dynamic Consolidation — An Unusual Application In Treating Liquefiable Saturated Sandy Loam Deposits, Yihui Qiu, Shuju Fan, Weiyuan Fan, Melyun Shi Mar 1991

Twice Dynamic Consolidation — An Unusual Application In Treating Liquefiable Saturated Sandy Loam Deposits, Yihui Qiu, Shuju Fan, Weiyuan Fan, Melyun Shi

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

More innovative methods of ground treatment have replaced traditional methods. Dynamic consolidation, for example, has been applied widespreadly in China. Presented in this paper is a case history of adopting the twice dynamic consolidation method to improve liquefiable saturated loesslike sandy loam deposit, since the site for the Aluminum Material Company which is located at the suburb of Talyuan, China, Is geotechnically adverse. In this project the effective depth of improvement increased significantly. Judged from the ln-situ investigation and laboratory triaxial shear test, the liquefaction potential was eliminated as predicted.

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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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Session 4: Discussions And Replies, Multiple Authors Mar 1991

Session 4: Discussions And Replies, Multiple Authors

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

No abstract provided.

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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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General Report Session 4: Dynamic Earth Pressures And Seismic Design Of Earth Retaining Structures, R. Richards Jr. Mar 1991

General Report Session 4: Dynamic Earth Pressures And Seismic Design Of Earth Retaining Structures, R. Richards Jr.

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

The great number of significant variables which effect the seismic behavior of retaining structures make this both a fascinating subject and a difficult one. The ten papers in this session cover both elastic and plastic aspects of analysis and design for a wide variety of wall types. To help put them in perspective, a new, fundamental seismic free-field solution will be reviewed briefly. This will serve as a benchmark from which the effects of changing the lateral boundary condition by introducing various types of walls can then be evaluated.

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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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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 Comparison And Study On Artificial Boundaries: Conceptual Aspects, Zifa Wang Mar 1991

A Comparison And Study On Artificial Boundaries: Conceptual Aspects, Zifa Wang

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

The paper first analyzes the characteristics of various artificial boundaries (similarity and dissimilarity) and the derivation conditions of the boundaries. The problems involved in applying the artificial boundary in numerical computation and the solution to the problem are also discussed in the paper.

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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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Analysis Of Bridges For Seismic Hazard Mitigation In Kentucky, Yu Ouyang, Vincent P. Drnevich, David L. Allen Mar 1991

Analysis Of Bridges For Seismic Hazard Mitigation In Kentucky, Yu Ouyang, Vincent P. Drnevich, David L. Allen

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

The priority routes have been selected for Western Kentucky which shares the most hazardous New Madrid seismic zone. As the vital links on the priority routes, bridges need to be protected from collapse during earthquakes in order to maintain the access to the route for subsequent emergency traffic. In this paper, a support-loss type of bridge collapse due to earthquake induced abutment sliding is analyzed and corresponding criteria to this type of collapse is established. The analysis methods for existing bridge abutment are advanced. A computer program based on the methods is developed and applied to evaluate the potential earthquake …

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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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Anti-Seismic Reinforcement Of Pipelines In A Liquefied Ground, Takashi Akiyoshi, Kunihiko Fuchida Mar 1991

Anti-Seismic Reinforcement Of Pipelines In A Liquefied Ground, Takashi Akiyoshi, Kunihiko Fuchida

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

An anti-seismic structural-reinforcemental method for buried pipelines is presented and analytically investigated on the effectiveness for lateral flow of liquefied grounds during earthquakes. The proposed method of the reinforcement is to fix main pipelines with expansion joints to parallel auxiliary continuous pipes using iron-plates. Stiffness of liquefied soils is around pipes is represented as a coefficient of subgrade reaction between liquefied sand deposits and pipes, based on the experimental results. Analysis of the pipeline-soil spring systems is conducted using the modified transfer matrix method. Computations are performed with respect to the displacement, strain, stress, and rotational angle of joint of …

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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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Deformation Of Soil To Seismic Waves Reflected On Foundation, L. R. Stavnitser Mar 1991

Deformation Of Soil To Seismic Waves Reflected On Foundation, L. R. Stavnitser

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

Interacting with constractions foundations during earthquake elastic seismic waves form reflected waves field which interference with coming waves lead to an increase of stresses near by foundation. These stresses can exceed the earth limit of elasticity and become the reason of limited plastic deformations region formation and residual foundations seismosettlements. In order to describe this phenomenon solution of the problem of non-standard elastic wave interaction with shifting base of foundation is obtained for conditions of caused by interference reflected plastic wave generation behind the front of which medium load relief takes place which can be described using bilinear elastic-plastic model …

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Dynamic Behavior Of Slender Structures On Their Prestressed Foundations, Phong M. Luong Mar 1991

Dynamic Behavior Of Slender Structures On Their Prestressed Foundations, Phong M. Luong

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

A non-destructive vibratory testing, using impulsive tension slacking has been devised for the quality and safety control of overhead line towers. Several structural control experiments have been conducted on four-legged towers resting on three types of foundations: concrete stepped or pedestal blocks, steel piles and prestressed foundations. Experimental results have given significant vibratory signatures in close connection with the geotechnical response characteristics of both such slender structures and their foundations. The control of foundation mechanical behavior may be very useful in cases of earthquake resistant construction and design. This paper presents some significant results of the test program.

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Dynamic Compliance Of Pile Group Considering Nonlinear Behavior Around Piles, Koichi Kobayashi, Shintaro Yao, Nozomu Yoshida Mar 1991

Dynamic Compliance Of Pile Group Considering Nonlinear Behavior Around Piles, Koichi Kobayashi, Shintaro Yao, Nozomu Yoshida

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

Static and dynamic loading test of a foundation are carried out to obtain the behavior of a pile and a pile group. A conventional analysis based on the elastic wave theory are modified to obtain the complex rigidity of a pile group and are compared with the test results. It is shown that the analysis based on the conventional elastic wave theory are not enough to predict the dynamic behavior of piles since they do not take into account both the effect of slip and/or separation between the pile surface and the surrounding ground and the nonlinear behavior of the …

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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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Dynamic Response Of Foundations On Two-Parameter Media, A. Alvapplllai, M. O. Faruque, M. Zaman Mar 1991

Dynamic Response Of Foundations On Two-Parameter Media, A. Alvapplllai, M. O. Faruque, M. Zaman

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

A finite element algorithm is presented to analyze the dynamic response of rectangular foundations resting on an elastic medium. The foundation is modeled by rectangular thin plate elements and the supporting elastic medium is represented by the two parameter model proposed by Vlasov. The natural frequencies of the foundation-elastic medium are investigated. A parametric study is conducted to examine the effects of the edge and corner forces, that are accounted for in the two parameter model, on the dynamic response of a plate subjected to a moving vertical force.

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Earthquake Damages Influenced By Soil Conditions In Historical Buildings In Istanbul, Nafiz Çamlibel Mar 1991

Earthquake Damages Influenced By Soil Conditions In Historical Buildings In Istanbul, Nafiz Çamlibel

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

This paper is based on the study of the damages by earthquakes on the historical buildings constructed in Bysantine and Ottoman period and represents a preliminary approach to the problem of identifying the causes of these damages influenced by soil conditions. In this paper, some aspects of soil conditions and foundations systems are given related to the preservation of monument, especially the presentation is concentrated on the following topics: • An estimation of seismic area and on Design basis response spectra for historical buildings. • Geotechnical problems of the old city Istanbul. • Statistical aspects of masonry of Bysantine and …

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Earthquake Resistant Piles Reinforced With Ground Walls, Yoshiaki Nagataki, Hiroaki Senoo Mar 1991

Earthquake Resistant Piles Reinforced With Ground Walls, Yoshiaki Nagataki, Hiroaki Senoo

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

A method for reducing earthquake load acting on piles by means of ground walls installed around pile foundation is proposed. First, a shaking table test was carried out. Test specimens are 1/40 scale structural models, which consist of soil, piles and a building with or without ground walls. The pile head moment of the specimens with ground walls show only 60% of that of the specimens without the ground walls. An FEM analysis was carried out for both cases and the results were compared with the test results. The comparison showed a good agreement. Furthermore, a simplified calculation method is …

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Evaluation Of Seismic Soil-Structure Interaction (Ssi) By Different Approaches, Dan Mircea Ghiocel, Dan Ghiocel, Traian Mauna Mar 1991

Evaluation Of Seismic Soil-Structure Interaction (Ssi) By Different Approaches, Dan Mircea Ghiocel, Dan Ghiocel, Traian Mauna

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

The paper investigates the seismic SSI effects for rigid type structures. Structural response is computed by modal synthesis versus frequency response approach. The main aspects analysed are as follows: a) the seismic SSI effects on structural response; b) shortcomings in the current SSI computational procedure; c) seismic structure –soil-structure interaction (SSSI) effects on structural response of neighbouring heavy buildings. Two case studies are presented: a shearwell multistory building (SMB) on soft clay and a massive reactor building (RB). Seismic response quantities are accelerations, displacements, stresses, floor response spectra (FRS) and spectra amplification functions (SAF).

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Experimental Studies On An Embedded Soil-Structure Interaction In A Case Of Hard Supporting Ground, Tomoyuki Lnukai, Masanori Izumi, Tamio Lmazawa, Eisuke Tanimoto Mar 1991

Experimental Studies On An Embedded Soil-Structure Interaction In A Case Of Hard Supporting Ground, Tomoyuki Lnukai, Masanori Izumi, Tamio Lmazawa, Eisuke Tanimoto

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

In order to investigate the embedment effects exerted on the vibration behavior of reactor building, a series of tests is being carried out employing the use of a large-scale test model constructed on hard ground. This paper describes the embedment effects obtained from the forced vibration tests for the following items: 1) dynamic characteristics of soil-structure interaction system; 2) dynamic ground impedance; 3) soil pressure and so on.

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