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.

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.

Confining stress and static shear effects in cyclic liquefaction

2001 ◽  
Vol 38 (3) ◽  
pp. 580-591 ◽  
Author(s):  
Y P Vaid ◽  
J D Stedman ◽  
S Sivathayalan
Keyword(s):  
Initial Density ◽  
Confining Pressure ◽  
Empirical Method ◽  
Shear Stresses ◽  
Confining Stress ◽  
Liquefaction Resistance ◽  
Sand Liquefaction ◽  
Cyclic Resistance ◽  
Cyclic Resistance Ratio ◽  
Static Shear

Liquefaction resistance of a sand under cyclic loading is assessed and the effects of the levels of confining pressure and static shear on resistance to liquefaction are investigated. Site-specific values of the resistance under specified levels of confining and static shear stresses are measured in the laboratory. The measured values are compared with those which would be predicted by the application of empirical multiplying factors Kσ and Kα to the reference resistance at 100 kPa effective confining stress with no static shear. It is shown that Kσ and Kα are not independent, as assumed in current practice. The combined factor Kσ × Kα resulting from the empirical method is shown to underestimate the cyclic resistance ratio regardless of the initial density and confining and static shear levels. The degree of conservatism is most dramatic at looser density states.Key words: sand, liquefaction, static, cyclic, static shear, confining stress.

scholarly journals EVALUATING LIQUEFACTION POTENTIAL OF PUMICEOUS DEPOSITS THROUGH FIELD TESTING: CASE STUDY OF THE 1987 EDGECUMBE EARTHQUAKE

2020 ◽  
Vol 53 (2) ◽  
pp. 101-110
Author(s):  
Rolando Orense ◽  
Mohammad Asadi ◽  
Mark Stringer ◽  
Michael Pender
Keyword(s):  
Field Tests ◽  
Field Testing ◽  
Soil Liquefaction ◽  
Clear Understanding ◽  
Undisturbed Soil ◽  
Liquefaction Potential ◽  
Volcanic Origin ◽  
The North ◽  
Cyclic Resistance ◽  
Testing Case

Pumice materials, which are problematic from an engineering viewpoint, are widespread in the central part of the North Island. Considering the impacts of the 2010-2011 Christchurch earthquakes, a clear understanding of their properties under earthquake loading is necessary. For example, the 1987 Edgecumbe earthquake showed evidence of localised liquefaction of sands of volcanic origin. To elucidate on this, research was undertaken to investigate whether existing empirical field-based methods to evaluate the liquefaction potential of sands, which were originally developed for hard-grained soils, are applicable to crushable pumice-rich deposits. For this purpose, two sites, one in Whakatane and another in Edgecumbe, were selected where the occurrence of liquefaction was reported following the Edgecumbe earthquake. Manifestations of soil liquefaction, such as sand boils and ejected materials, have been reported at both sites. Field tests, including cone penetration tests (CPT), shear-wave velocity profiling, and screw driving sounding (SDS) tests were performed at the sites. Then, considering estimated peak ground accelerations (PGAs) at the sites based on recorded motions and possible range of ground water table locations, liquefaction analysis was conducted at the sites using available empirical approaches. To clarify the results of the analysis, undisturbed soil samples were obtained at both sites to investigate the laboratory-derived cyclic resistance ratios and to compare with the field-estimated values. Research results clearly showed that these pumice-rich soils do not fit existing liquefaction assessment frameworks and alternate methods are necessary to characterise them.

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.

scholarly journals Unified Evaluation of Consolidation Parameters for Low to High Plastic Range of Cohesive Soils

2021 ◽  
Vol 40 (1) ◽  
pp. 93-103
Author(s):  
Zia ur Rehman State ◽  
Khalid Farooq ◽  
Hassan Mujtaba ◽  
Usama Khalid
Keyword(s):  
Cohesive Soil ◽  
Soil Samples ◽  
Engineering Properties ◽  
Cohesive Soils ◽  
High Plasticity ◽  
Index Properties ◽  
Undisturbed Soil ◽  
Index Compression ◽  
The Right ◽  
Consolidation Parameters

Knowing the engineering properties of geomaterials is imperative to make the right decision while designing and executing any geotechnical project. For the economical and safe geotechnical design, quick characterization of the compressibility properties of the cohesive soil is often desirable; these properties are indeed tedious to determine through actual tests. Therefore, correlating the consolidation parameters of the soils with its index properties has a great significance in the geotechnical engineering field. Several attempts have been made in the past to develop correlations between the consolidation parameters and index properties of the cohesive soils, within certain limitations. However, there is still a need to develop such correlations based on the extensive database, composing of unified plasticity range of soils, i.e., low to high plasticity. In the current study, 148 undisturbed soil specimens were obtained from different areas of Pakistan. Out of which 120 samples were utilized to develop correlations, and 28 samples were used to check the validity of the developed correlations. In order to enhance the index properties database, 30 more bentonite mixed soil samples were prepared and tested accordingly. Correlations to envisage different consolidation parameters such as compression index, compression ratio and coefficient of volume compressibility were developed using 150 cohesive soil samples of low to high plasticity. In addition, the performance of these developed correlations was verified on a set of 40 soil samples and compared with the performance of different correlations available in the literature. The percentage deviation in the prediction of compressibility characteristics through developed correlations in the present study was found to be very less, which endorsed the excellent reliability of the developed correlations.

Rancangan Sistem Pengukuran Kinerja Berbasis Human Resource Scorecard Pada Universitas Muhammadiyah Luwuk

2020 ◽  
Vol 10 (1) ◽  
pp. 63-71
Author(s):  
Nurhaeda Abbas ◽  
Anggraini Sukmawati ◽  
Muhammad Syamsun
Keyword(s):  
Performance Measurement ◽  
Human Resource ◽  
Performance Measurement System ◽  
Group Discussions ◽  
Strategic Objectives ◽  
Depth Interview ◽  
And Performance ◽  
The Right ◽  
Hierarchy Process ◽  
The Relationship

Today the performance measurement of Muhammadiyah Luwuk uUniversity’s performance has not formulated yet based on University’s vision and mission. It will affect the strategic steps needed and performance improvement efforts in the future.  Human resource scorecard is the right system to be applied in Muhammadiyah Luwuk University. The purpose of this study is to designed a performance measurement system at Muhammadiyah Luwuk University using the Human Resource Scorecard with four perspectives: stakeholder, academic management and kemuhammadiyaan, operational and innovation, as well as and learning. Data was analyzed by analytical hierarchy process method. This research was conducted by distributing questionnaires, focus group discussions and in-depth interview with stakeholders at Muhammadiyah Luwuk University. The results showed that there were 14 strategic objectives and 33 key performance indicators to be achieved by the priority objectives, which are: empowerment and development of faculty, increased administrative process quality, improved sound budget performance and, improvement of the relationship with stakeholders.

scholarly journals Hand Preference and Performance in Basketball Tasks

2019 ◽  
Vol 16 (22) ◽  
pp. 4336 ◽  
Author(s):  
Emanuela Gualdi-Russo ◽  
Natascia Rinaldo ◽  
Alba Pasini ◽  
Luciana Zaccagni
Keyword(s):  
Professional Training ◽  
Factor Model ◽  
Hand Preference ◽  
Control Group ◽  
Basketball Players ◽  
Confirmatory Factor Analyses ◽  
Left Hand ◽  
Confirmatory Factor ◽  
And Performance ◽  
The Right

The aims of this study were to develop and validate an instrument to quantitatively assess the handedness of basketballers in basketball tasks (Basketball Handedness Inventory, BaHI) and to compare it with their handedness in daily activities by the Edinburgh Handedness Inventory (EHI). The participants were 111 basketballers and 40 controls. All subjects completed the EHI and only basketballers filled in the BaHI. To validate the BaHI, a voluntary subsample of basketballers repeated the BaHI. Exploratory and confirmatory factor analyses supported a two-factor model. Our results show that: (i) Handedness score (R) in daily actions did not differ between basketball players (R by EHI = 69.3 ± 44.6) and the control group (R by EHI = 64.5 ± 58.6); (ii) basketballers more frequently favored performing certain sport tasks with the left hand or mixed hands (as highlighted by R by BaHI = 50.1 ± 47.1), although their choice was primarily the right hand in everyday gestures; and (iii) this preference was especially true for athletes at the highest levels of performance (R by BaHI of A1 league = 38.6 ± 58.3) and for those playing in selected roles (point guard’s R = 29.4 ± 67.4). Our findings suggest that professional training induces handedness changes in basketball tasks. The BaHI provides a valid and reliable measure of the skilled hand in basketball. This will allow coaches to assess mastery of the ball according to the hand used by the athlete in the different tasks and roles.

scholarly journals Sensitivity and Performance Analyses of the Distributed Hydrology–Soil–Vegetation Model Using Geomorphons for Landform Mapping

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2032
Author(s):  
Pâmela A. Melo ◽  
Lívia A. Alvarenga ◽  
Javier Tomasella ◽  
Carlos R. Mello ◽  
Minella A. Martins ◽  
...  
Keyword(s):  
Complex Terrain ◽  
Overland Flow ◽  
Hydrological Model ◽  
Model Performance ◽  
Soil Parameters ◽  
Vegetation Model ◽  
Landform Classification ◽  
Physically Based ◽  
And Performance ◽  
Streamflow Simulation

Landform classification is important for representing soil physical properties varying continuously across the landscape and for understanding many hydrological processes in watersheds. Considering it, this study aims to use a geomorphology map (Geomorphons) as an input to a physically based hydrological model (Distributed Hydrology Soil Vegetation Model (DHSVM)) in a mountainous headwater watershed. A sensitivity analysis of five soil parameters was evaluated for streamflow simulation in each Geomorphons feature. As infiltration and saturation excess overland flow are important mechanisms for streamflow generation in complex terrain watersheds, the model’s input soil parameters were most sensitive in the “slope”, “hollow”, and “valley” features. Thus, the simulated streamflow was compared with observed data for calibration and validation. The model performance was satisfactory and equivalent to previous simulations in the same watershed using pedological survey and moisture zone maps. Therefore, the results from this study indicate that a geomorphologically based map is applicable and representative for spatially distributing hydrological parameters in the DHSVM.

scholarly journals No Evidence of Perceptual Pseudoneglect in Alexithymia

2021 ◽  
Vol 11 (3) ◽  
pp. 376
Author(s):  
Carmelo Mario Vicario ◽  
Gabriella Martino ◽  
Alex Marcuzzo ◽  
Giuseppe Craparo
Keyword(s):  
Right Hemisphere ◽  
Line Bisection ◽  
Mental Condition ◽  
Bisection Task ◽  
Rightward Shift ◽  
Behavioral Evidence ◽  
And Performance ◽  
The Right ◽  
Line Bisection Task ◽  
Tas 20

Neuroscience research links alexithymia, the difficulty in identifying and describing feelings and emotions, with left hemisphere dominance and/or right hemisphere deficit. To provide behavioral evidence for this neuroscientific hypothesis, we explored the relationship between alexithymia and performance in a line bisection task, a standard method for evaluating visuospatial processing in relation to right hemisphere functioning. We enrolled 222 healthy participants who completed a version of the 20-item Toronto Alexithymia Scale (TAS-20), which measures alexithymia, and were asked to mark (bisect) the center of a 10-cm horizontal segment. The results document a significant rightward shift in the center of the line in participants with borderline and manifest alexithymia compared with non-alexithymic individuals. The higher the TAS-20 score, the greater the rightward shift in the line bisection task. This finding supports the right hemisphere deficit hypothesis in alexithymia and suggests that visuospatial abnormalities may be an important component of this mental condition.

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