Engineering Commons^™

Site Effects Estimated From Microtremor Measurements At Selected Strong Motion Stations In Taiwan, Kohji Tokimatsu, Toru Sekiguchi

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

Microtremor measurements are conducted using arrays of sensors at six strong motion stations in Taiwan where the peak ground accelerations over 400 cm/s² were recorded during the 1999 Chi-Chi earthquake. Shallow shear wave velocity profiles of these stations are estimated based on an inverse analysis of microtremor dispersion characteristics and H/V spectra. At Wufeng (TCU065) where building damage was the most extensive among others, a thick soft surface layer with a shear wave velocity less than or equal to about 200 m/s overlies a stiff layer with Vs greater than 400 m/s at a depth of about 30 m. …

The Crack Development Due To Liquefaction Of Sand Lenses During Earthquake Loading, S. M. Mir Mohammad Hosseini, F. Nateghi-A.

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

The failure of sand lenses during earthquake loadings has caused many damages to the ground and yet its mechanism has not been investigated extensively. In this paper the results of an analytical studies involving the mechanism of crack development of a sand lens due to liquefaction, are presented. A single loose and saturated sand lens embedded inside a stiff clay deposit, which will liquefy due to the earthquake loading, is modeled by finite element method. The principles of fracture mechanics were used and the soil behavior was considered as a non-linear elasto-plastic material. The computer package of NISA was used …

Predicting The Maximum And Distribution Of Displacements On Liquefaction-Induced Lateral Spreads, Alan F. Rauch, James R. Martin Ii

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

Lateral spreading is the mostly horizontal movement of gently sloping ground due to liquefaction in shallow soil deposits. To assess the seismic hazards related to lateral spreading, estimates are needed of the maximum potential ground movement at these sites. One approach to this problem is to predict, using empirical models, the mean and standard deviation of the displacement magnitudes across the surface of a lateral spread. Then, using a probability density function, the maximum likely deformation at the site can be predicted with a suitable degree of conservatism. In the analysis described here, probability density functions are studied for modeling …

Spt Energy Transfer Measurements For Liquefaction Evaluations In The Northeast, Lawrence F. Johnsen, Stanley M. Bemben, Jon J. Jagello

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

Energy measurements were made during Standard Penetration testing at Northeast locations with 16 drilling rigs having various energy transfer mechanisms including automatic safety hammers, wire line safety hammers, rope and cathead safety hammers and donut hammers. The energy measurements were used to correct the field N values to the standard 60% reference energy transfer. Examples are provided to illustrate the significant effect which the energy transfer efficiency has when working with Building Codes. The uncertainty regarding the use of field N values as opposed to energy corrected N values when using the codes is discussed.

Experimental Study On Reduction Of The Horizontal Subgrade Reaction Due To Liquefaction, Hiroshi Kobayashi, T. Azuma, K. Tamura, T. Morimitsu, Gary L. Manhart, David Gervan

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

It is important to evaluate resistance strength of foundation and the subgrade reaction of soil surrounding the foundation during an earthquake when a bridge is constructed on liquefiable ground. In this study, we evaluated reduction coefficient of the horizontal subgrade reaction during liquefaction D_E based on shaking table tests. We examined the influence of liquefaction resistance factor F_L, subgrade shear strain amplitude and velocity of the ground on the reduction coefficient D_E from the test results. We made model grounds varying relative soil density in a container, which was placed on a shaking table. A piston …

Dynamic Response Of Seabed Under Wave-Induced Loading, Maotian Luan, Dong Wang

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

In this paper, the characteristics of the development of effective stresses and pore water pressure in elastic or elasto-plastic seabed with time under a sequence of wave loading are studied by virtue of numerical finite element analyses. Compared with analytical solution for elastic problem, the numerical procedure proposed can deal with complicated situation of seabed and can predict residual pore pressure. For inelastic seabed, bounding-surface hypoplasticity model is employed to describe the nonlinear stress-strain relationship of sand under cyclic loading. The development pattern of pore pressure under undrained condition obtained from laboratory experiments is not necessary in the numerical simulation.

Cpt Evaluation Of Liquefaction Potential Using Neural Networks, Pradeep U. Kurup, Nitin K. Dudani

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

The increasing popularity of the cone penetration test (CPT) for site investigations has led to several methods for predicting liquefaction potential from CPT data. This paper describes a feed-forward neural network model trained by back-propagation for predicting liquefaction potential. The model requires the following seven input variables: cone resistance, total vertical stress, effective vertical stress, earthquake magnitude, maximum horizontal acceleration at ground surface, the mean grain size D₅₀, and the seismic shear-stress ratio. A total of ninety-six data sets from different sites around the world were used for training, and eighty-two data sets were used for testing and …

Liquefaction Studies On Silty Clays Using Cyclic Triaxial Tests, . Anubhav, N.S.V. Kameswara Rao

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

Liquefaction of saturated soils during earthquake often had been a major cause of damage to structures. Since beginning the liquefaction studies were concentrated on sandy soils, as the sandy soils are known to be more susceptible to liquefaction. However, observations from some sites in China and Loma-Prieta earthquakes show that soils with high plastic fines are also susceptible to liquefaction. Isotropically consolidated undrained cyclic triaxial tests were conducted on undisturbed samples of silty clay soil and results of these tests are used to verify the methods based on SPT data. Slow cyclic tests were performed to investigate the development of …

The Cause Of Ground Fissures Radiating From The Footing Of A Bridge Pie Generated By The 1995 Great Hanshin Earthquake, Takashi Tazoh, Maysayoshi Sato, Hideyuki Mano

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

After the 1995 Great Hanshin Earthquake, ground fissures were found to have radiated from the footing of a bridge pier. Simple experimental and numerical studies were carried out to investigate the cause of these fissures. This paper clarified that the ground fissures appeared not as a result of the force due to the lateral spreading of the liquefied soil acting to the back of the footing of the bridge pier, but due to the movement of the ground behind the riverbank toward the river caused by the collapse of the riverbank.

Geomorphological Criteria For Evaluating Liquefaction Potential Considering The Level-2 Ground Motion In Japan, Kazue Wakamatsu, Akio Yamamoto, Ichiro Tanaka

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

In response to a bitter experience in the 1995 Hyogo-ken Nambu (Kobe) earthquake, the level-2 ground motion, extraordinarily strong shaking motion that would be caused by an earthquake directly under the area such as the 1995 earthquake, has been considered in seismic design of various kind of structures in Japan, in addition to the level-l general ground motion. Geomorphological criteria in the manual for zonation on liquefaction hazard issued by Land Planning Agency, which have been used a qualitative estimate of liquefaction potential were demanded to keep up with the above-mentioned trend of the time. The purpose of this study …

3-D Modeling Of Liquefaction Phenomenon Using Distinct Element Method, N. Ravichandran, Kimiro Meguro

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

Liquefaction is one of the most important, complex and controversial topics in geotechnical earthquake engineering. Since Niigata earthquake in 1964, it has been popularly recognized that the liquefaction induced ground failures cause severe damage to the built environment. To take measures against such damage, understanding the mechanism of liquefaction and its associated phenomena from macroscopic and microscopic viewpoints is very important. There are two approaches, which are experimental and numerical ones, to study them. Although discussion from the macroscopic viewpoints can be done by experiments, it is not so easy to perform experiment to obtain microscopic information on liquefaction and …

Liquefaction Analysis Of A Petroleum Tank-Ground-Pile Ring System In Reclaimed Ground Near Seashore, A. Yashima, F. Zhang, K. Sawada, R. Uzuoka

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

In this paper, liquefaction analysis (LIQCA2D, LIQCA3D) of a petroleum tank-ground-foundation system is conducted using a dynamic finite element-finite difference method. The nonlinearity of the ground is simulated with a kinematic hardening elastoplastic model, which has been verified by a series of hollow cylindrical torsional shear tests and been proved that it can well predict the behaviors of soils such as the liquefaction strength curve, the stress-strain relation as well as the effective stress paths during cyclic loading. In the numerical analyses, an FEM-DEM analytical method is adopted to the soil-water coupled analysis. The petroleum tank is built on a …

Modeling Uncertainty In Seismic Stability And Earthquake Induced Displacement Of Earth Slopes Under Short Term Conditions, Azm S. Al-Homoud, Wisam W. Tahtamoni

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

Different models were developed for evaluating the probabilistic three-dimensional (3-D) stability analysis of earth slopes and embankments under earthquake loading using both the safety factor and the displacement criteria of slope failure. These models are formulated and incorporated within a computer program (PTDDSSA). The probabilistic models evaluate the probability of failure under seismic loading considering the different sources of uncertainties involved in the problem. A sensitivity analysis was conducted on the different parameters involved in the developed models by applying those models to a well-known landslides (Congress Street) under different levels of seismic hazard. The hypocentral distance and earthquake magnitude …

Model Tests On Mitigation Of Liquefaction-Induced Subsidence Of Dike By Using Embedded Sheet-Pile Walls, Taka-Aki Mizutani, Ikuo Towhata

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

Several earthquakes in the 1990’s revealed the problem of significant subsidence of river dikes induced by subsoil liquefaction. Although soil improvement is the most reliable solution to avoid the onset of liquefaction, the substantial length of liquefaction-prone dikes together with the economical reasons does not allow this solution. It is aimed, therefore, to mitigate the subsidence to a certain extent so that a fatal flooding is avoided. The present study examines the possibility of installing sheet pile walls at toes of river dikes. Shaking table tests were conducted for this purpose and the effects of sheet pile walls were studied. …

Seismic Response Of Normally Consolidated Cohesive Soils In Gently Inclined Submerged Slopes, Giovanna Biscontin, Juan M. Pestana, Farrokh Nadim, Knut Andersen

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

The geological profile of submerged slopes on the continental shelf typically includes soft cohesive soils with layer thicknesses ranging from a few meters to tens or hundreds of meters. The response of these soils in simple shear tests is largely influenced by the presence of an initial consolidation shear stress, inducing anisotropic stress-strain-strength properties which depend also on the direction of shear. In this paper, a new simplified effective-stress-based model describing the behavior of normally to lightly overconsolidated cohesive soils is used in conjunction with a one-dimensional seismic site response analysis computer code to illustrate the importance of accounting for …

Effects Of Vertical Seismic Accelerations On Slope Displacements, Armando Lucio Simonelli, Pietro Di Stefano

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

The behaviour of earth slopes under seismic conditions can be effectively studied by evaluating the suffered displacements, which are key parameters in the recent performance design approaches (Pianc/PTCII/WG34, 2001). Different methodologies have been developed to evaluate displacements (Whitman, 1993). Slope instabilities caused by yielding due to seismic inertial forces can be studied by methods based on the well-known model of a rigid block sliding on a plane surface (Newmark 1965). These methodologies utilise accelerometric time histories which allow to take into account the real characteristics of the seismic motion (Simonelli and Viggiani 1995). Displacement analyses are traditionally performed adopting only …

Definition Of Seismic Hazard Degree Of Dams And Their Territories, Armenia, Styopa Karapetyan, Tamara Babayan, Levon Manukyan

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

The work is devoted to define the seismic hazard degree of four dams of Armenia: Azat, Tavshoot, Haldioom, and Joghaz. The problem required the execution of major geological-geophysical, seismological, tool and theoretical researches. Such studies of the dams in Armenia were carried out for the first time, on the complex of methods designed by us. All research was reduced to a solution of the primary problem, i.e. definition of expected maximum horizontal accelerations (EMHA) of seismic vibrations on the altitude of the investigated dams with compiling of the corresponding epyuras of the distribution of accelerations. For obtaining epyuras the values …

Seismic Stability And Rehabilitation Analysis Of A Hydraulic Fill Dam, Selami O. Tezcan, Shobha K. Bhatia, Stefan Fiegle

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

This paper focuses on the seismic stability analysis of a hydraulic fill dam built in the mid-1920’s. The material properties of the dam were characterized using data from soil borings, standard penetration, cone penetration and shear wave velocity tests. An effective stress analysis approach was used for the analysis. A finite difference code, Fast Lagrangian Analysis of Continua (FLAG), provided static and dynamic shear stresses, excess pore water pressures, and deformations. The results obtained from the effective stress analyses are compared to the results of liquefaction potential analyses based on SPT and CPT data. For seismic excitation, a real acceleration-time …

Effects Of Ground Improvement And Armored Embankment To The Displacements Of The Seawalls And Back Fill During Earthquake, Marmoru Kanatani, Hitoshi Tochigi, Tadashi Kawai, Hiroyuki Ishikawa

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

Large shaking table tests of the caisson type seawalls under various conditions were conducted in order to investigate the effects of the armored embankment and the improvement of sandy seabed and backfill by densification to the deformation of the seawalls during earthquake. Main results obtained from the shaking table tests were as follows : (1) Seaward horizontal displacement and tilting of the caisson were drastically reduced by the existence of the armored embankment in front of the caisson. (2) Improvement of the sandy seabed by densification method just under the rubble mound was much effective to reduction of the displacements …

Seismic Analysis Of A Partially-Buried Drinking Water Reservoir, Sri T. Srithar, Upul D. Atukorala

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

This paper describes the details of the seismic analyses undertaken to retrofit the Kersland drinking water reservoir in Vancouver, British Columbia, Canada. The reservoir has a storage capacity of about 67 million litres, measures approximately 100 m by 150 m, and is partially buried. The walls are supported by above-ground soil berms. Seismic upgrading of the reservoir required an assessment of the loads imposed on the perimeter walls of the reservoir due to the design seismic event. The problem of soil-structure and structure-fluid interaction during seismic loading is complex, and could significantly increase the lateral forces on the reservoir wall. …

Numerical Simulation Of Sliding Of An Earth Dam During The 1995 Kobe Earthquake, Tomoya Iwashita

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

The Kobe Earthquake in Japan caused shallow sliding on the upstream slope below the water level of the Kitayama Dam. This paper briefly stated the results of post-earthquake surveys and tests of this earth dam. The FE model of the dam was prepared based on the detailed results of in-situ tests and laboratory material tests. The numerical analysis was performed by the effective stress analysis to simulate the performance of the dam during the Kobe Earthquake. The analysis resulted in that large residual deformation and shear strain occurred at the shallow area of the upstream slope below the water level. …

A Case History: Seismic Analysis Of The Retaining Wall Of The "Sacro Convento" In Assisi (Italy), Teresa Crespellani, Claduia Madiai, Giovanni Vannucchi

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

The aim of the present work is to analyse the seismic behaviour of the retaining wall of the square in front of the Basilica di San Francesco at Assisi that during a long seismic crisis occurred in September 1997 suffered some damage. Static, pseudo-static and dynamic analyses have been carried out on four significant sections of the wall. The data for the analysis derive from the geometric survey of the structures, the survey of the state of the damage, the measurement of the rotation movements of the wall, the collection of stratigraphic and geotechnical data, as well as the accelerometric …

Foundation Sign Correction In Stochastic Analysis Procedures, K. Zand Parsa, H. Zamani Abyane

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

There are “ABS, SRSS, CQC, MSRSS…” methods in stochastic analysis of structures, that are based on the mean of the response squares. One of the most accurate stochastic methods is MSRSS, that is defined as equation (1).

E[y²]=∑_j=1^N R_j² + 2 ∑_k=j+1^NR_jk

The maximum modal responses are positive or singles, and therefore direction of the forces act on the foundation are alike. In these cases foundation analysis is not valid and the force sign correction must be used. In this paper, besides considering the stochastic methods shortly, a method for …

Seismic Evaluation And Retrofit Of A Major Natural Gas Transmission System, Dharma Wijewichreme, Allen Mitchell, Trevor Fitzell

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

The performance of pipeline systems under seismic loading is an important consideration in regions subject to earthquakes. Experience from previous seismic events indicates that earthquake-induced permanent ground displacements are one of the key geotechnical hazards to pipelines. This paper briefly describes an evaluation of the vulnerability of a natural gas transmission system to seismic hazards, along with some of the remedial treatments that were implemented. The work was carried out for BC Gas Utility Ltd. in the Lower Mainland of British Columbia, Canada. Initially, a regional study was carried out to identify components of the gas pipeline system that are …

An Experimental Study Of Seismic Bearing Capacity Of Shallow Footings, Awad A. Al-Karni, Muniram Budhu

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

In this paper, the results of an experimental investigation on the response of model shallow footings to horizontal accelerations are presented. The experiments were conducted on square and rectangular footings resting on or embedded in a dry sand and shaken in a shake box. The shake box was designed to subject the soil to simple shear conditions during shaking. Model footings, constructed from lead, were used to study the seismic bearing capacity. The influence of the magnitude and frequency of the horizontal accelerations, the static bearing capacity safety factor, the footing shape, the depth of embedment, and the relative density …

Newmarkian Analysis Of Liquefied Flow In Centrifuge Model Earthquakes, S. K. Haigh, S. P. G. Madabhushi, K. Soga, Y. Taji, Y. Shamoto

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

This paper describes the application of a modified Newmarkian analysis method to the estimation of slope deformations during liquefaction-induced lateral spreading. The analysis method requires a pore-pressure history either predicted using a suitable constitutive model, or measured during a centrifuge or shaking-table test, to calculate the variation of threshold acceleration with time. Comparison of predicted displacements using this procedure and displacements measured in centrifuge mode1 tests with the same pore-pressure history shows good agreement.

Preliminary Test Results For Full Scale Drilled Shaft Under Cyclic Lateral Loading, Kerop Janoyan, Jonathan P. Stewart, John W. Wallace

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

Preliminary results are presented of a field testing program for a full-scale, large diameter cast-in-drilled-hole (CIDH) shaft/column under cyclic lateral loading. The shaft was extensively instrumented to enable high precision, redundant section curvature measurements, measurements of pressure at the soil-shaft interface around the shaft perimeter, and in situ measurements of concrete quality. The principal objective of the testing was to characterize the soil-shaft interaction across a wide displacement range to gain insight into the adequacy of existing design guidelines (which are based principally on the testing of small diameter piles) for the large diameter shafts commonly used to support highway …

Analytical Evaluation For Seismic Behavior Of Shore Structures On Liquefied Area During Earthquakes, Kenji Hayashi, Tomonari Imono, Tamotsu Matsui, Kazuhiro Oda, Hitoshi Miyamoto

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

In this paper, focusing on the caisson type quay wall, which is a typical gravity type of shore structures, the seismic behavior of the structures was discussed when the liquefaction occurs, by applying the dynamic response analysis and a simplified prediction method which was proposed by the authors. Firstly, a simplified and reasonable method for predicting the seismic behavior of shore structures during earthquakes was proposed. In the proposed analytical method, the structure is replaced by a simplified model, and the ground contacting the structure by subgrade springs. There are two types of subgrade springs employed as elasto-plastic spring and …

Consideration Of Earthquake Resistant Of Large Fill Dams, Shigeru Tani

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

There are two approaches for estimating the stability of fill dams during earthquakes. The first method determines the ultimate resistance of dams by using theoretical analyses, such as slide analysis and finite element method. In actuality, fill dams do not immediately collapse even when the safety factor by slide analysis is less than 1.0. The finite element method estimates safety based on displacement, which cannot be accurately determined with analytical methods. The second approach estimates the maximum seismic force fill dams can resist based on past earthquake damage to fill dams. In this study, we used this second method to …

Centrifuge Model Test On The Stability Of A Clayey Ground Improved By Deep Mixing Method With A Low Improvement Ratio, Noriyuki Horii, Yasuo Toyosawa, Satoshi Tamate, Hideo Hashizume

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

In this study, centrifuge model tests and numerical analysis were carried out to investigate effects of improvement by deep mixing method (DMM). Model grounds used in model tests were (1) unimproved ground (easel), (2) improved ground with vertical soil columns under toe of slopes (case2), (3) improved ground with vertical soil columns under shoulder of slopes (case3), (4) improved ground with inclined soil columns under toe of slopes (case4), and (5) improved ground with inclined soil columns under shoulder of slopes (case5). The improvement ratio was about 10% for all test cases except easel. The embankment was constructed by sand …