Results and implications of seismic performance studies for Duncan Dam

1994 ◽  
Vol 31 (6) ◽  
pp. 979-988 ◽  
Author(s):  
P.M. Byrne ◽  
A.S. Imrie ◽  
N.R. Morgenstern
Keyword(s):  
Seismic Performance ◽  
Soil Parameters ◽  
Confining Stress ◽  
Foundation Soil ◽  
Dam Foundation ◽  
Indirect Approach ◽  
Empirical Correction ◽  
Undisturbed Samples ◽  
Flow Slides ◽  
Design Earthquake

Screening-level studies indicated large zones of the foundation soil beneath Duncan Dam could be triggered to liquefy under the design earthquake, resulting in flow slides that could lead to breaching of the dam. In these studies, estimates of the key soil parameters were obtained from an indirect procedure using penetration tests and Seed's chart, which is based on field experience during past earthquakes together with empirical correction factors for high confining stress and static bias. This is state-of-the-practice procedure in North America and is used because of the difficulty in retrieving and testing undisturbed samples of sand. With the high confining stresses present at the site, the indirect approach gave very low values of the key liquefaction properties of the soil, and the use of such low values in analyses indicated that major and costly remedial measures were required. Thus a more direct approach was undertaken. This involved both direct and semidirect determination of the key soil parameters through an extensive laboratory study based on testing of undisturbed samples obtained by freezing in situ. The results showed that both the triggering resistance and the residual strength values of the soil were very much higher than those obtained from the indirect approach. Analyses carried out using direct measurement of the key soil parameters indicated that the dam, in fact, would be stable. Key words : embankment dam, foundation liquefaction, sand, seismic performance, triggering resistance, undisturbed sample.

Evaluation of liquefaction potential of foundation soils at Duncan Dam

1994 ◽  
Vol 31 (6) ◽  
pp. 951-966 ◽  
Author(s):  
V.S. Pillai ◽  
R.A. Stewart
Keyword(s):  
Engineering Properties ◽  
Soil Parameters ◽  
Confining Stress ◽  
Undisturbed Soil ◽  
Liquefaction Potential ◽  
Sand Liquefaction ◽  
Cyclic Resistance ◽  
And Performance ◽  
Design Earthquake ◽  
The Right

A comprehensive program of field, laboratory, and analytical investigations was carried out to evaluate the potential of liquefaction for the foundation soils at Duncan Dam. Duncan Dam was completed in 1967 under the Columbia River Treaty in southeastern British Columbia. The 39 m high zoned embankment dam is founded on a sequence of sands, silts, and gravels. Some of the foundation soils may liquefy during earthquake loading and this would affect the stability and performance of the dam. The liquefaction studies were carried out in two phases to characterize the engineering properties of the foundation soils and to assess its potential for triggering liquefaction using the total stress approach. This paper describes methods of assessment of liquefaction potential using soil parameters based on field penetration data (Seed's method) and laboratory testing of undisturbed soil samples obtained in situ after freezing the ground (Lab method) and presents the results of triggering analysis. Influence of confining stress (Kσ) and initial static shear stress (Kα) on liquefaction were investigated and site-specific Kσ and Kα curves were developed.For the design earthquake (M 6.5, PGA = 0.12g) both the Lab method and Seed's method predict a significant extent of liquefaction of the foundation soils under the downstream slope in the right half of the dam. Key words : sand, liquefaction, confining stress, density, cyclic resistance ratio.

Analysis of the Influences of Soil Parameters on the Settlement of Storage Tank Foundation

2011 ◽  
Vol 90-93 ◽  
pp. 372-376
Author(s):  
Xu Dong Zhang ◽  
Shuai Wang ◽  
Ran Gang Yu
Keyword(s):  
Permeability Coefficient ◽  
Storage Tank ◽  
Compression Modulus ◽  
Soil Parameters ◽  
Foundation Soil ◽  
Consolidation Settlement ◽  
Water Filling ◽  
Oil Tank ◽  
Tank Bottom ◽  
Main Factor

The settlement characteristics of storage tank foundation at water-filling preloading stage and stable loading stage was analyzed based on numerical simulation. And the influences of foundation soil parameters on the settlement of storage tank foundation were studied. The research results show that Uplift appears at the place 1.3D away from the center of oil tank bottom, and the final uplift value is 10mm.The main factor which influences the consolidation speed of storage tank foundation is permeability coefficient. The consolidation settlement is determined by compression modulus and load.

Influence of Spud-Can-Soil Interaction Modeling and Parameters on the Reliability Index of Neka Drilling Jack-Up Platform

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
M. R. Emami Azadi
Keyword(s):  
Reliability Index ◽  
Clayey Soil ◽  
Interaction Model ◽  
Soil Parameters ◽  
The Caspian Sea ◽  
Foundation Soil ◽  
Soil System ◽  
Dense Sand ◽  
Interaction Modeling ◽  
Jack Up

In the present study, the influence of spud-can-soil modeling and parameters on the reliability index of jack-up platform is investigated. Neka platform is studied as a case, which is a three-leg drilling jack-up type platform located in water depth of about 91 m in the Caspian Sea region. Various spud-can-soil interaction models such as pinned, fixed-base, hyperelastic, and nonlinear elastoplastic spud-can models are applied. The soil type is varied from loose to dense sand and also from soft NC clay to very stiff OC Clay. The effect of bias and coefficient of variation (COV) of the spud-can-soil interaction modeling and also the soil parameters such as the effective interface soil friction angle and also the undrained shear strength of clayey soil are studied. The results showed that inclusion of spud-can-soil interaction may have a considerable effect on the reliability of the jack-up platform. In particular, the bias and COV of soil have shown to have more significant effect on the reliability of jack-up platform in loose sand and soft clayey type soils. It is also found that bias in strength modeling of jack-up itself has less profound effect on the reliability index of the jack-up-foundation-soil system. Importance factors of spud-can-soil modeling are found to be quite considerable. The key aspect is that the inclusion of jack-up-spud-can-soil interaction is more crucial with respect to the reliability of jack-up platform than the choice of interaction model itself.

scholarly journals Modeling of shear stiffness reduction from database of axial load tests on pile foundations

2019 ◽  
Vol 92 ◽  
pp. 13002
Author(s):  
Fawad S. Niazi ◽  
Paul W. Mayne
Keyword(s):  
Shear Modulus ◽  
Axial Load ◽  
Small Strain ◽  
Pile Foundations ◽  
Soil Parameters ◽  
Foundation Soil ◽  
Nonlinear Load ◽  
Stiffness Reduction ◽  
Nonlinear Stress ◽  
Load Tests

Initiating at the small-strain shear modulus (Gmax), the mechanical nonlinear stress-strain-strength behavior of soil manifests in the form of modulus reduction, typically expressed in normalized form as Gop/Gmax. Here, Gop is the operative shear modulus – a reduced stiffness value corresponding to strain levels that the soil is experiencing. Assessment of Gop is critical to reliable predictions of load-related deformations within the soil. Among the various categories of loading, deep foundations and pilings exhibit a typical mechanism of axial load transfer to the foundation soil. For friction type piles, the stiffness reduction mostly takes place along the pile shaft-soil interface. Within the framework of an analytical solution, the back analyses from the results of load tests on pile foundations, together with the knowledge of pile geometries and soil parameters, provide an outline for evaluation of Gop at different load increments. This paper explains the methodology employed to develop stiffness reduction curves (Gop/Gmax) as a function of pseudo-strain (γp = wt/d), where, wt = settlement at the pile top, and d = pile diameter. Algorithms that integrate the plasticity characteristics of the soil are also presented. The results afford an improved evaluation of the complete nonlinear load-settlement (Q-wt) response for pile foundations under axial loads.

Seismic stability of the Revelstoke earthfill dam

1982 ◽  
Vol 19 (1) ◽  
pp. 63-75
Author(s):  
K. S. Khilnani ◽  
P. M. Byrne ◽  
K. K. Yeung
Keyword(s):  
Time History ◽  
Seismic Stability ◽  
Triaxial Tests ◽  
Dynamic Resistance ◽  
Foundation Soil ◽  
Dynamic Stresses ◽  
Cyclic Triaxial Tests ◽  
Undisturbed Samples ◽  
History Of ◽  
Liquefaction Failure

The foundation soil beneath the earthfill section of the proposed Revelstoke dam comprises, in part, a deep silt-clay layer that contains pockets of loose to compact saturated sands. Removal of this material beneath the core of the dam was required for seepage and erosion control. Analyses were performed to determine if considerations of earthquake stability would also require removal of this material beneath the shells.A factor of safety against the occurrence of a liquefaction failure beneath the shells was determined by comparing the dynamic resistance obtained from cyclic triaxial tests on undisturbed samples with the time history of dynamic stresses caused by the design earthquakes. Preliminary analyses clearly indicated that the silt-clay beneath the upstream shell should be removed. Beneath the downstream shell, the computations indicated factors of safety at the lower range of acceptable values and a portion of the silt-clay beneath the downstream shell was removed so that only minor damage would occur even in the unlikely event of liquefaction of the material left in place.

Post-liquefaction stability and deformation analysis of Duncan Dam

1994 ◽  
Vol 31 (6) ◽  
pp. 967-978 ◽  
Author(s):  
V.S. Pillai ◽  
F.M. Salgado
Keyword(s):  
Residual Strength ◽  
Limit Equilibrium ◽  
Unconsolidated Sediments ◽  
Deformation Analysis ◽  
Soil Parameters ◽  
Confining Stress ◽  
Undisturbed Soil ◽  
Sand Liquefaction ◽  
Strength Performance ◽  
And Performance

Duncan Dam is a 39 m high zoned embankment and is founded on a deep deposit of unconsolidated sediments consisting of sands, silts, and gravels that are susceptible to liquefaction during earthquake loading. A comprehensive program of field, laboratory, and analytical investigations was conducted to evaluate the liquefaction potential of the foundation soils and performance of the dam during an earthquake. This paper describes the evaluation procedures and analyses and presents results of the post-liquefaction stability and deformation analysis of the dam. Analyses were carried out based on the total stress approach using two methods, namely the Lab method and Seed's method. The Lab method is a site–specific (direct), laboratory-based approach utilizing soil parameters from laboratory tests on undisturbed soil samples obtained in situ after freezing the ground. Seed's method is indirect and is based on field penetration data and past experience from earthquakes. The Lab method indicates that the residual strength of the liquefied sand is dependent on the effective confining stress, whereas Seed's method does not. Post-liquefaction deformations of the dam were computed using a pseudodynamic finite element procedure applying pre- and post-liquefaction stress–strain relationships and gravity and inertia forces satisfying the work–energy theorem. The Lab method predicts factors of safety of greater than 1.3 for the post-liquefaction limit equilibrium stability and acceptable deformations. On the contrary, Seed's method predicts factors of safety equal to or less than 1.0 and large deformations indicative of a flow slide. The merits of the two methods are discussed. Key words : sand, liquefaction, residual strength, performance, deformation.

A shaking table substructure testing method for the structural seismic evaluation considering soil-structure interactions

2020 ◽  
Vol 23 (14) ◽  
pp. 3024-3036
Author(s):  
Guoshan Xu ◽  
Yong Ding ◽  
Jingfeng Xu ◽  
Yongsheng Chen ◽  
Bin Wu
Keyword(s):  
Seismic Performance ◽  
Storage Tank ◽  
Soil Structure ◽  
Experimental Results ◽  
Shaking Table ◽  
Seismic Evaluation ◽  
Maximum Acceleration ◽  
Foundation Soil ◽  
Testing Method ◽  
Liquid Height

A novel shaking table substructure testing method that includes interaction forces determined by actuator forces and shaking table dynamic parameters is proposed and validated. The seismic performance of a storage tank that incorporates soil-structure interactions is investigated by the method proposed in this article. The experimental results show that the proposed shaking table substructure testing method is an efficient alternative method of evaluating the seismic performance of a storage tank that incorporates soil-structure interactions. The experimental results show that the influence of the soil-structure interactions increases as the stiffness of the foundation soil decreases, which was demonstrated by the results showing that the displacement and acceleration responses of the storage tank decrease as the stiffness of the foundation soil decreases. Moreover, the influence of the soil-structure interactions increases as the liquid height increases, which was illustrated by the decreased displacement responses of the storage tank with increases in the liquid height. The maximum acceleration response of the storage tank occurred at the liquid surface height.

Seismic Performance and Cost Evaluations of Reinforced Concrete Buildings with Various Ductility in Moderate Seismic Zone

2014 ◽  
Vol 08 (02) ◽  
pp. 1450005 ◽  
Author(s):  
Virote Boonyapinyo ◽  
Norathape Choopool
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Seismic Loading ◽  
Building Design ◽  
Seismic Zone ◽  
Cost Estimates ◽  
Diagram Method ◽  
Performance Point ◽  
Failure State ◽  
Design Earthquake

This study is focused on the effects of the new standard of the building design under seismic loading in Thailand (DPT 1302-52) on cost estimates and the seismic performance of nine-story reinforced concrete apartment buildings with various ductility in moderate seismic zone and a gravity load designed (GLD) building. Both the nonlinear static pushover and nonlinear dynamic analyses are applied. Comparisons of performance point (PF) evaluation of studied frames are investigated by three different methods, namely, capacity spectrum method (CSM), inelastic demand diagram method (IDDM), and nonlinear time history analysis (NTHA) method. Five selected ground motion records are investigated in the analyses. In order to examine the influence of design ductility classes, the seismic forces on moment resisting frame buildings are defined according to the new standard of the building design under seismic loading in Thailand with ductility from 8, 5, and 3, corresponding to special ductile frame (SDF), intermediate ductile frame (IDF), and ordinary ductile frames (ODF), respectively. For the cost estimates, ODF is the most expensive among ODF, IDF, and SDF. Costs of SDF and IDF in Chiang Mai are quite similar. The results show that SDF is more ductile than that of ODF, however, the strength of SDF is less than ODF. The results indicate that all frames including GLD are able to withstand a design earthquake. The study also found that the average ductilities at the failure state for SDF, IDF, ODF, and GLD are 1.45, 1.42, 1.28, and 1.17, respectively. The average PGAs at the failure state for SDF, IDF, ODF, and GLD are 0.85 g, 0.83 g, 0.63 g, and 0.35 g, respectively when these buildings have the volumetric ratio of horizontal confinement within joint panel greater than 0.003. Moreover, at the failure state of GLD with volumetric ratio of horizontal confinement within joint panel less than 0.003, the average PGA is only 0.17 g which is lower than the design earthquake of PGA of 0.39 g in the draft DPT. The SDF and IDF are the two best options in consideration of cost and seismic performance.

Performance of a raft foundation supporting a multistorey structure

1988 ◽  
Vol 25 (1) ◽  
pp. 138-149 ◽  
Author(s):  
A. O. Landva ◽  
A. J. Valsangkar ◽  
J. C. Alkins ◽  
P. D. Charalambous
Keyword(s):  
Soil Structure ◽  
Thick Layer ◽  
Field Testing ◽  
Soil Structure Interaction ◽  
Foundation Soil ◽  
Structure Interaction ◽  
Raft Foundation ◽  
Undisturbed Samples ◽  
Clayey Silt ◽  
Load Cells

A nine-storey structure was recently constructed on a raft founded on a 30 m thick layer of clayey silt at Fredericton, New Brunswick. Detailed soil investigations included conventional borings and self-boring pressuremeter, field vane, and flat dilatometer tests performed at the site. In addition to the field testing, undisturbed samples were obtained and tested in the laboratory to determine the compressibility and shear strength characteristics. To compare the performance of the foundation with the design assumptions, instrumentation consisting of piezometers, contact pressure load cells, and settlement points was installed. The instrumentation was monitored at regular intervals during the construction stage and at 6 month intervals following the completion of the building. This report presents (i) the results of the field and laboratory testing, (ii) the results of the field monitoring, and (iii) the results of a finite element computer analysis of the foundation-soil interaction. Key words: raft foundation, instrumentation, clayey silt, compressibility, soil tests, soil–structure interaction.

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