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.

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.

ANALISIS PENANGGULANGAN KELONGSORAN TANAH PADA RUAS JALAN GUNUNG TUGEL PATIKRAJA BANYUMAS

2017 ◽  
Vol 14 (1) ◽  
pp. 53
Author(s):  
Arwan Apriyono ◽  
Sumiyanto Sumiyanto ◽  
Nanang Gunawan Wariyatno
Keyword(s):  
Limit Equilibrium ◽  
Retaining Wall ◽  
Limit Equilibrium Method ◽  
Pile Foundations ◽  
Soil Parameters ◽  
The Road ◽  
Realistic Option ◽  
Stable Conditions ◽  
Using Data ◽  
Wall Slope

Gunung Tugel is an area that located Patikraja Region, Southern Banyumas. Thetopography of the area is mostly mountainous with a slope that varies from flat to steep. Thiscondition makes to many areas of this region potentially landslide. In 2015, a landslideoccurred in Jalan Gunung Tugel. The Landslide occurred along 70 meters on the half of theroad and causing traffic Patikraja-Purwokerto disturbed. To repair the damage of the road andavoid further landslides, necessary to analyze slope stability. This study is to analyze landslidereinforcement that occurred at Gunung Tugel and divides into 3 step. The first step is fieldinvestigation to determine the condition of the location and dimensions of landslides. Thesecond step is to know the soil parameters and analyzes data were obtained from the field. Andthe final step is analyzed of the landslide reinforcement by using data obtained from thepreceding step. In this research, will be applied three variations of reinforcement i.e. retainingwall, pile foundation and combine both of pile foundations and retaining wall. Slope stabilityanalysis was conducted using limit equilibrium method. Based on the analysis conducted onthe three variations reinforcement, combine both of pile foundations and retaining wall morerecommended. Application of and combine both of pile foundations and retaining wall is themost realistic option in consideration of ease of implementation at the field. From thecalculations have been done, in order to achieve stable conditions need retaining wall withdimensions of 2 meters high with 2,5 meters of width. DPT is supported by two piles of eachcross-section with 0.3 meters of diameter along 10 meters with 1-meter in space. Abstrak: Gunung Tugel adalah salah satu daerah yang terletak di Kecamatan PatikrajaKabupaten Banyumas bagian selatan. Kondisi topografi daerah tersebut sebagian besar berupapegunungan dengan kemiringan yang bervariasi dari landai sampai curam. Hal inimenyebabkan banyak daerah di wilayah Gunung Tugel yang berpotensi terjadi bencana tanahlongsor. Pada tahun 2015, peristiwa longsor kembali terjadi di ruas Jalan Gunung Tugel.Kelongsoran yang terjadi sepanjang 70 meter pada separuh badan jalan tersebut menyebabkanarus lalu lintas patikraja-purwokerto menjadi terganggu. Untuk memperbaiki kerusakan jalandan mencegah kelongsoran kembali, diperlukan analisis perkuatan tanah terhadap lerengtersebut. Studi analisis penanggulangan kelongsoran jalan yang terjadi di Gunung Tugel inidilakukan dengan tiga tahapan. Tahapan pertama adalah investigasi lapangan untukmengetahui kondisi lokasi dan dimensi longsor serta mengambil sampel tanah di lapangan.Tahap kedua adalah melakukan pengujian parameter tanah dan analisis data yang diperolehdari lapangan. Tahapan yang terakhir adalah analisis penanggulangan longsor denganmenggunakan data yang diperoleh dari tahapan sebelumnya. Pada penelitan ini, akanditerapkan tiga variasi perkuatan lereng yaitu dinding penahan tanah (DPT), turap dan DPTyang dikombinasikan dengan pondasi tiang. Analisis stabilitas lereng dilakukan dengan metodekeseimbangan batas. Berdasarkan hasil analisis yang dilakukan terhadap ketiga variasiperkuatan, DPT dengan kombinasi tiang pancang lebih direkomendasikan. Penerapan DPTyang dikombinasikan dengan minipile merupakan pilihan yang paling realistis denganpertimbangan tingkat kemudahan pelaksanaan di lapangan. Dari perhitungan yang telahdilakukan, untuk mencapai kondisi stabil diperlukan DPT dengan dimensi tinggi 2 meterdengan lebar bawah 2,5 meter. DPT tersebut ditopang oleh dua tiang tiap penampangmelintang dengan diameter 0,3 meter sepanjang 10 meter dengan jarak antar tiang 1 meter.kata kunci: tanah longsor, perkuatan tanah, metode keseimbangan batas

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 Should We Use Unilateral or Bilateral Tasks to Assess Maximal and Explosive Knee Extensor Strength in Patients with Knee Osteoarthritis? A Cross-Sectional Study

2021 ◽  
Vol 10 (19) ◽  
pp. 4353
Author(s):  
Jonas Pfeifle ◽  
David Hasler ◽  
Nicola Maffiuletti
Keyword(s):  
Knee Osteoarthritis ◽  
Clinical Relevance ◽  
Knee Extensor ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
Strength Performance ◽  
Explosive Strength ◽  
Knee Extensor Strength ◽  
And Performance ◽  
Voluntary Contractions

Deficits in maximal and explosive knee extensor strength, which are usually assessed with unilateral tasks, are substantial in patients with knee osteoarthritis (KOA). The aim of this study was to investigate the clinical relevance of unilateral vs. bilateral tasks for assessing knee extensor strength in patients with KOA. This was achieved primarily by comparing unilateral and bilateral inter-limb strength asymmetries and secondarily by examining the relationship between unilaterally and bilaterally measured strength, and performance-based and self-reported function. Twenty-four patients with unilateral KOA (mean age: 65 ± 7 years) performed isometric gradual and explosive maximal voluntary contractions to assess, respectively their maximal and explosive strength. Performance-based and self-reported function were also evaluated with standard functional tests and questionnaires, respectively. Inter-limb asymmetries of maximal and explosive strength did not differ significantly between unilateral (mean asymmetry: 26 ± 15%) and bilateral tasks (22 ± 21%). In the same way, the relationships between knee extensor strength—measured either unilaterally or bilaterally—and performance-based or self-reported function were not influenced by the type of task. In conclusion, it does not seem to make a difference in terms of clinical relevance whether maximal and explosive knee extensor strength are evaluated with unilateral or bilateral tasks in KOA patients.

scholarly journals Laboratory development of a vertically oriented penetrometer for shallow seabed characterization

2016 ◽  
Vol 53 (1) ◽  
pp. 93-102 ◽  
Author(s):  
Fauzan Sahdi ◽  
David J. White ◽  
Christophe Gaudin ◽  
Mark F. Randolph ◽  
Noel Boylan
Keyword(s):  
Soil Surface ◽  
Site Investigation ◽  
Soil Strength ◽  
Small Scale ◽  
Soil Parameters ◽  
Embedment Depth ◽  
Fine Grained ◽  
Centrifuge Models ◽  
Measured Resistance ◽  
And Performance

Current site investigation practice for offshore pipeline design relies on soil parameters gathered from boreholes or in situ test soundings to depths of 1–2 m below the mudline. At these depths, the fine-grained seabed is very soft and possesses low undrained strength, which can be difficult to measure. This paper describes a centrifuge test programme undertaken to evaluate the feasibility and performance of a novel penetrometer designed to assess the shallow strength of soft seabed over continuous horizontal profiles. This device is termed the vertically oriented penetrometer (VOP). Tests were performed on a normally consolidated kaolin sample, with the VOP translated horizontally at velocities ranging from 1 to 30 mm/s, after embedding the VOP at 30 and 45 mm depths. All tests involved many cycles of VOP forward and backward movement to assess its potential to derive the ratio of intact to fully remoulded strength. Strength determination is achieved by dragging the VOP at a specified embedment depth along the soil surface, and deriving the soil strength from the measured resistance as if the VOP were a laterally loaded pile. The VOP is shown to yield comparable strength measurements to that of a T-bar penetrometer. The VOP is a potentially valuable addition to the range of tools used to characterize soil strength, both in small-scale centrifuge models and, following practical development, potentially also in the field.

Feasibility Study of S-Lay Installation for Deepwater SCRs and Pipelines

2020 ◽  
Author(s):  
Jing Hou ◽  
Chenteh Alan Yu ◽  
Yongming Cheng ◽  
Gurudutt Bangalore ◽  
Hao Song
Keyword(s):  
Load Capacity ◽  
Cost Effective ◽  
Acceptance Criteria ◽  
Peak Period ◽  
Strength Performance ◽  
High Production Rate ◽  
Support Reaction ◽  
Dynamic Amplification ◽  
And Performance ◽  
Welded Pipe

Abstract The J-lay and S-lay are two common methods for SCR and pipeline installations. When using the S-lay installation method, onboard welded pipe joints leave the vessel horizontally and are guided to the seabed over a stinger structure. The pipe is lowered using tensioners. With the advantage of high production rate, Slay can be a cost-effective solution for deepwater riser and pipeline installation. Based on HYSY201 installation vessel, this paper investigates the feasibility of S-lay installation for deepwater SCRs and pipelines to be used in South China Sea. It first introduces the SCRs and pipelines to be used for a deep draft semi-submersible for the Lingshui 17-2 project. It then presents the S-lay installation vessel HYSY201 and S-lay configuration. The hydrodynamic motion analysis for a Response Amplitude Operator (RAO) was computered for HYSY201 in different environmental headings. With the site-specific metocean design basis, this paper presents an installation procedure, analysis methodology, and acceptance criteria. The study covers different sizes of SCRs and pipelines to investigate the feasibility of S-lay installation. The study starts from the static installation analysis of SCRs and pipelines and includes different installation steps. The acceptance criteria are examined for the pipes at over bend and sag bend regions. The support reactions load on the stinger structure are reported at each step. The dynamic analysis is selectively performed to evaluate Dynamic Amplification Factors (DAFs) of support reaction loads especially for roller box supports on the stinger structure. The sensitivity of DAFs to wave parameters such as wave height and peak period is analyzed as well. The extreme support reaction loads are computed for evaluating the strength performance of the stinger structure. The feasibility of S-lay installation for deepwater SCRs and pipelines is determined by the global performance of SCRs and pipelines, installation vessel hold back tension and A&R winch load capacity, and performance of the stinger structure. Based on the study work, this paper finds the feasibility of S-lay installation of deepwater SCRs and pipelines for Lingshui 17-2 project using the installation vessel of HYSY201.

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.

Simulation of time-dependent movements in Syncrude tailings dyke foundation

1998 ◽  
Vol 35 (2) ◽  
pp. 284-298 ◽  
Author(s):  
AMP Wedage ◽  
N R Morgenstern ◽  
D H Chan
Keyword(s):  
Residual Strength ◽  
Time Dependent ◽  
Deformation Analysis ◽  
Foundation Soil ◽  
Clay Shale ◽  
Soil Plasticity ◽  
Rate Dependent ◽  
Rate Effects ◽  
Clearwater Formation ◽  
Using Data

Foundation movements at the Syncrude tailings dyke continued over several years in response to the construction of the dyke. Major movements have been observed in a relatively narrow layer of previously sheared clay-shale material of the Clearwater Formation. The residual strength of this highly plastic clay increases with the rate of shear. By reviewing the existing literature on the rate effects on residual strength and using data from new experiments on Clearwater Clay Shale, a general correlation between soil plasticity and rate effects is found. This rate dependence of the residual strength of Clearwater clay shale has been incorporated into a deformation analysis, which made it possible to compute time-dependent movements of the foundation soil to a satisfactory level. By using a rate-dependent plasticity model, a prediction of anticipated foundation velocities and how they decrease with time may be achieved.Key words: finite element, rate effects, residual strength, Syncrude tailings dyke, time-dependent movements.

The Finite Element Model of Discontinuous Rock Masses

2011 ◽  
Vol 243-249 ◽  
pp. 2948-2951 ◽  
Author(s):  
Heng Bin Wu ◽  
Ze Ping He
Keyword(s):  
Finite Element ◽  
Limit Equilibrium ◽  
Element Model ◽  
Discontinuous Deformation Analysis ◽  
Deformation Analysis ◽  
Sliding Surface ◽  
Discontinuous Deformation ◽  
Discontinuous Rock ◽  
Element Theory ◽  
The Finite Element Model

The traditional limit equilibrium theory could not consider the discontinuous property of rock slope, and the existing research methods for the discontinuous rock mass confined to the Discrete Element Method and Discontinuous Deformation Analysis. Based on the finite element theory, considering the strength reduction of the joint mechanical parameters, the slope stability with one or two sets joints are analyzed in this paper. The results show that, the sliding surface for one set joint slope is close to the joint dip, and the sliding surface for two sets joints slope is close to the control joint dip.

scholarly journals Probabilistic and Fuzzy Arithmetic Approaches for the Treatment of Uncertainties in the Installation of Torpedo Piles

2008 ◽  
Vol 2008 ◽  
pp. 1-26 ◽  
Author(s):  
Denise Margareth Kazue Nishimura Kunitaki ◽  
Beatriz Souza Leite Pires de Lima ◽  
Alexandre Gonçalves Evsukoff ◽  
Breno Pinheiro Jacob
Keyword(s):  
Production Systems ◽  
Free Fall ◽  
Design Tool ◽  
Soil Parameters ◽  
Fuzzy Arithmetic ◽  
Mooring Lines ◽  
Oil Exploitation ◽  
The Monte Carlo Method ◽  
And Performance ◽  
Offshore Oil

The “torpedo” pile is a foundation system that has been recently considered to anchor mooring lines and risers of floating production systems for offshore oil exploitation. The pile is installed in a free fall operation from a vessel. However, the soil parameters involved in the penetration model of the torpedo pile contain uncertainties that can affect the precision of analysis methods to evaluate its final penetration depth. Therefore, this paper deals with methodologies for the assessment of the sensitivity of the response to the variation of the uncertain parameters and mainly to incorporate into the analysis method techniques for the formal treatment of the uncertainties. Probabilistic and “possibilistic” approaches are considered, involving, respectively, the Monte Carlo method (MC) and concepts of fuzzy arithmetic (FA). The results and performance of both approaches are compared, stressing the ability of the latter approach to efficiently deal with the uncertainties of the model, with outstanding computational efficiency, and therefore, to comprise an effective design tool.

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