Load-transfer platform behaviour in embankments supported on semi-rigid columns: implications of the ground reaction curve

Post-construction data from an instrumented geosynthetic reinforced column supported embankment (GRCSE) on drilled displacement columns in Melbourne, Australia, show the time-dependent development of arching over the 2 year monitoring period and a strong relationship between the development of arching stresses and subsoil settlement. A ground reaction curve is adopted to describe the development of arching stresses and good agreement is found for the period observed thus far. Predictions of arching stresses and load-transfer platform behaviour are presented for the remaining design life. Four phases of arching stress development (initial, maximum, load-recovery, and creep strain phases) are shown to describe the time-dependent, and subsoil-dependent, development of arching stresses that can be expected to occur in many field embankments. Of the four phases, the load-recovery phase is the most important with respect to load-transfer platform design, as it predicts the breakdown of arching stresses in the long term due to increasing subsoil settlement. This has important implications in assessing the appropriate design stress for the geosynthetic reinforcement layers, but also the deformation of the load-transfer platform in the long term.

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Mechanics of Tubes Composed of Interlocking Building Blocks

10.31224/osf.io/a98qf ◽

2022 ◽

Author(s):

Kyle Mahoney ◽

Thomas Siegmund

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Load Transfer ◽

Building Blocks ◽

Maximum Load ◽

Finite Element Models ◽

Element Analysis ◽

Internal Load ◽

Deformation Response ◽

Good Agreement

Topologically interlocking material (TIM) systems are composed of convex polyhedral units placed such that building blocks restrict each other's movement. Here, TIM tubes are considered as rolled monolayers of such assemblies. The deformation response of these assembled tubes under diametrical loading is considered. This investigation employs experiments on additivelymanufactured physical realizations and finite element analysis with contact interactions. The internal load transfer in topologically interlocking tubes is rationalized through inspection of the distribution of minimum principalstress. A thrust-line (TL) model for the deformation of topologically interlocking tubes is established. The model approximates the deformation response of the assembled tubes as the response of a collection of Misestrusses aligned with paths of maximum load transfer in the system. The predictions obtained with the TL-model are in good agreement with results of finite element models. Accounting for sliding between building blocks in theTL-model yields a predicted response more similar to experimental results with additively manufactured tubes.

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Analysis of Time-Dependent Soil Behavior above High-Filled Cut-and-Cover Tunnels Using Discrete Element Method

10.21203/rs.3.rs-509520/v1 ◽

2021 ◽

Author(s):

Sheng Li ◽

Guoqiang Han ◽

I-HSUAN HO ◽

Li Ma ◽

Balasingam Muhunthan ◽

...

Keyword(s):

Discrete Element Method ◽

Load Transfer ◽

Earth Pressure ◽

Vertical Displacement ◽

Discrete Element ◽

Time Dependent ◽

Structural Safety ◽

Dependent Behavior ◽

Element Method

Abstract In the Northwest Loess Plateau of China that is full of mountains and deep valleys, high-filled cut-and-cover tunnels (HFCCTs) not only satisfy transportation demands, but they create usable land as well. Several studies have been conducted to investigate the feasibility of HFCCTs, but the time-dependent behavior of the significant backfill needed for HFCCTs has not been adequately examined. Settlement can be severely underestimated due to the time-dependent behavior of ultra-high backfill, and the earth pressure becomes redistributed accordingly. Therefore, the ability to predict the long-term behavior of backfill on HFCCTs is necessary to ensure the long-term safety of the structure. Using a discrete element method (DEM), the changes in vertical earth pressure (VEP), vertical displacement, and load transfer mechanisms above an HFCCT were investigated in this study under scenarios with and without considering backfill creep. The results show that the differential displacement of the soil and the surface settlement obviously increase due to creep and the subsequent cycles of primary and secondary consolidation. Moreover, the stress surrounding the HFCCT is redistributed, causing both the stress concentration and slope effect to weaken over time, but the VEP increases significantly. The micromechanical parameters also change correspondingly. Our results clearly show that the creep of high backfill soil must be considered carefully in HFCCT projects to ensure structural safety.

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Formulating Industry-Academic Collaborations That Work: Best Practices to Ensure a Strong Relationship After the Agreements are Signed

Technology & Innovation ◽

10.21300/21.2.2020.169 ◽

2020 ◽

Vol 21 (2) ◽

pp. 169-177

Author(s):

Michael B. Dilling ◽

Anne C. DiSante ◽

Ross Durland ◽

Christine E. Flynn ◽

Leonid Metelitsa ◽

...

Keyword(s):

Decision Making ◽

Best Practices ◽

Product Development ◽

Strong Relationship ◽

Governance Structure ◽

Collaborative Relationships ◽

Skill Sets ◽

Pragmatic Aspects

Collaborations between academia and industry are growing in scope, duration, and sophistication. The best collaborations recognize the unique strengths and skill sets of both parties and are structured to leverage what each party does best. In many cases, these collaborations develop into long-term relationships, and it is important to develop the systems and structures needed to support these relationships to ensure that they meet the needs of both sides. Successful collaborations require the formulation of a governance structure to facilitate communication, decision-making, assessment of progress, and the inevitable changes of direction that accompany product development. This panel explored the pragmatic aspects of successfully structuring collaborations and managing the relationships after the deal is done. Several dominant themes associated with successful collaborative relationships emerged from the discussion, and these will be explored in this article.

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Anthropologic Relationships among Prehistoric Northeastern Amerindians

North American Archaeologist ◽

10.2190/6g0g-8pd9-52t7-p0gq ◽

1980 ◽

Vol 1 (2) ◽

pp. 145-159

Author(s):

Edward F. Harris ◽

Nicholas F. Bellantoni

Keyword(s):

New York ◽

Gene Flow ◽

Material Culture ◽

New England ◽

Cultural Barriers ◽

Group Differences ◽

Phenetic Analysis ◽

Trade Relationships ◽

Good Agreement

Archaeologically defined inter-group differences in the Northeast subarea ate assessed with a phenetic analysis of published craniometric information. Spatial distinctions in the material culture are in good agreement with those defined by the cranial metrics. The fundamental dichotomy, between the Ontario Iroquois and the eastern grouping of New York and New England, suggests a long-term dissociation between these two groups relative to their ecologic adaptations, trade relationships, trait-list associations, and natural and cultural barriers to gene flow.

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Semi-Analytical Solution to Assess CO2 Leakage in the Subsurface through Abandoned Wells

Energies ◽

10.3390/en14092452 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2452

Author(s):

Tian Qiao ◽

Hussein Hoteit ◽

Marwan Fahs

Keyword(s):

Analytical Solution ◽

Storage Site ◽

Co2 Leakage ◽

Transient Pressure ◽

Flow Paths ◽

Abandoned Wells ◽

Diffusivity Equation ◽

Carbon Dioxide Co2 ◽

Good Agreement

Geological carbon storage is an effective method capable of reducing carbon dioxide (CO2) emissions at significant scales. Subsurface reservoirs with sealing caprocks can provide long-term containment for the injected fluid. Nevertheless, CO2 leakage is a major concern. The presence of abandoned wells penetrating the reservoir caprock may cause leakage flow-paths for CO2 to the overburden. Assessment of time-varying leaky wells is a need. In this paper, we propose a new semi-analytical approach based on pressure-transient analysis to model the behavior of CO2 leakage and corresponding pressure distribution within the storage site and the overburden. Current methods assume instantaneous leakage of CO2 occurring with injection, which is not realistic. In this work, we employ the superposition in time and space to solve the diffusivity equation in 2D radial flow to approximate the transient pressure in the reservoirs. Fluid and rock compressibilities are taken into consideration, which allow calculating the breakthrough time and the leakage rate of CO2 to the overburden accurately. We use numerical simulations to verify the proposed time-dependent semi-analytical solution. The results show good agreement in both pressure and leakage rates. Sensitivity analysis is then conducted to assess different CO2 leakage scenarios to the overburden. The developed semi-analytical solution provides a new simple and practical approach to assess the potential of CO2 leakage outside the storage site. This approach is an alternative to numerical methods when detailed simulations are not feasible. Furthermore, the proposed solution can also be used to verify numerical codes, which often exhibit numerical artifacts.

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Modeling cesium migration through Opalinus clay: a benchmark for single- and multi-species sorption-diffusion models

Computational Geosciences ◽

10.1007/s10596-021-10050-5 ◽

2021 ◽

Author(s):

Jesús F. Águila ◽

Vanessa Montoya ◽

Javier Samper ◽

Luis Montenegro ◽

Georg Kosakowski ◽

...

Keyword(s):

Time Discretization ◽

Single Species ◽

Opalinus Clay ◽

Sorption Behavior ◽

Diffusion Experiment ◽

Modeling Tools ◽

Cesium Sorption ◽

Code Performance ◽

Good Agreement

AbstractSophisticated modeling of the migration of sorbing radionuclides in compacted claystones is needed for supporting the safety analysis of deep geological repositories for radioactive waste, which requires robust modeling tools/codes. Here, a benchmark related to a long term laboratory scale diffusion experiment of cesium, a moderately sorbing radionuclide, through Opalinus clay is presented. The benchmark was performed with the following codes: CORE2DV5, Flotran, COMSOL Multiphysics, OpenGeoSys-GEM, MCOTAC and PHREEQC v.3. The migration setup was solved with two different conceptual models, i) a single-species model by using a look-up table for a cesium sorption isotherm and ii) a multi-species diffusion model including a complex mechanistic cesium sorption model. The calculations were performed for three different cesium boundary concentrations (10−3, 10−5, 10−7 mol / L) to investigate the models/codes capabilities taking into account the nonlinear sorption behavior of cesium. Generally, good agreement for both single- and multi-species benchmark concepts could be achieved, however, some discrepancies have been identified, especially near the boundaries, where code specific spatial (and time) discretization had to be improved to achieve better agreement at the expense of longer computation times. In addition, the benchmark exercise yielded useful information on code performance, setup options, input and output data management, and post processing options. Finally, the comparison of single-species and multi-species model concepts showed that the single-species approach yielded generally earlier breakthrough, because this approach accounts neither for cation exchange of Cs+ with K+ and Na+, nor K+ and Na+ diffusion in the pore water.

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In Situ Tests on Creep Behavior of Rock Mass with Joint or Shearing Zone in Foundation of Large-Scale Hydroelectric Projects

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.261-263.1097 ◽

2004 ◽

Vol 261-263 ◽

pp. 1097-1102 ◽

Cited By ~ 2

Author(s):

Jian Liu ◽

Xia Ting Feng ◽

Xiu Li Ding ◽

Huo Ming Zhou

Keyword(s):

Rock Mass ◽

Creep Behavior ◽

Large Scale ◽

Time Dependent ◽

Three Gorges Project ◽

Three Gorges ◽

The Three Gorges ◽

The Three Gorges Project

The time-dependent behavior of rock mass, which is generally governed by joints and shearing zones, is of great significance for engineering design and prediction of long-term deformation and stability. In situ creep test is a more effective method than laboratory test in characterizing the creep behavior of rock mass with joint or shearing zone due to the complexity of field conditions. A series of in situ creep tests on granite with joint at the shiplock area of the Three-Gorges Project and basalt with shearing zone at the right abutment of the Xiluodu Project were performed in this study. Based on the test results, the stress-displacement-time responses of the joints and basalt are analyzed, and their time-dependent constitutive model and model coefficients are given, which is crucial for the design to prevent the creep deformations of rock masses from causing the failure of the operation of the shiplock gate at the Three-Gorges Project and long-term stability of the Xiluodu arc dam.

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Comparison of numerical and standard sarnat grading using the NICHD and SIBEN methods

Journal of Perinatology ◽

10.1038/s41372-021-01180-w ◽

2021 ◽

Author(s):

Brian H. Walsh ◽

Chelsea Munster ◽

Hoda El-Shibiny ◽

Edward Yang ◽

Terrie E. Inder ◽

...

Keyword(s):

Predictive Ability ◽

Roc Curves ◽

Cerebral Injury ◽

Neonatal Encephalopathy ◽

Minimum Threshold ◽

Term Outcome ◽

Long Term Outcome ◽

Grading Systems ◽

Good Agreement

Abstract Objective The NICHD and SIBEN assessments are adapted from the Sarnat grade, and used to determine severity of neonatal encephalopathy (NE). We compare NICHD and SIBEN methods, and their ability to define a minimum threshold associated with significant cerebral injury. Study design Between 2016 and 2019, 145 infants with NE (77-mild; 65-moderate; 3-severe) were included. NICHD and SIBEN grade and numerical scores were assigned. Kappa scores described agreement between methods, and ROC curves their ability to predict MR injury. Results Good agreement existed between grading systems (K = 0.86). SIBEN defined more infants as moderate, and less as mild, than NICHD (p < 0.001). Both numerical scores were superior to standard grades in predicting MR injury. Conclusion Despite good agreement between methods, SIBEN defines more infants as moderate NE. Both numerical scores were superior to standard grade, and comparable to each other, in defining a minimum threshold for cerebral injury. Further assessment contrasting their predictive ability for long-term outcome is required.

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The Rate of Mutation and the Homozygous and Heterozygous Mutational Effects for Competitive Viability: A Long-Term Experiment With Drosophila melanogaster

Genetics ◽

10.1093/genetics/158.2.681 ◽

2001 ◽

Vol 158 (2) ◽

pp. 681-693 ◽

Cited By ~ 7

Author(s):

David Chavarrías ◽

Carlos López-Fanjul ◽

Aurora García-Dorado

Keyword(s):

Drosophila Melanogaster ◽

Minimum Distance ◽

Deleterious Mutations ◽

Regression Estimate ◽

Term Experiment ◽

Degree Of Dominance ◽

Long Term Experiment ◽

Rate Of Decline ◽

Good Agreement

Abstract The effect of 250 generations of mutation accumulation (MA) on the second chromosome competitive viability of Drosophila melanogaster was analyzed both in homozygous and heterozygous conditions. We used full-sib MA lines, where selection hampers the accumulation of severely deleterious mutations but is ineffective against mildly deleterious ones. A large control population was simultaneously evaluated. Competitive viability scores, unaffected by the expression of mutations in heterozygosis, were obtained relative to a Cy/L2 genotype. The rate of decline in mean ΔM ≈ 0.1% was small. However, that of increase in variance ΔV ≈ 0.08 × 10-3 was similar to the values obtained in previous experiments when severely deleterious mutations were excluded. The corresponding estimates of the mutation rate λ ≥ 0.01 and the average effect of mutations E(s) ≤ 0.08 are in good agreement with Bateman-Mukai and minimum distance estimates for noncompetitive viability obtained from the same MA lines after 105 generations. Thus, competitive and noncompetitive viability show similar mutational properties. The regression estimate of the degree of dominance for mild-to-moderate deleterious mutations was ∼0.3, suggesting that the pertinent value for new unselected mutations should be somewhat smaller.

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Non-coronary Interventions: An Introduction to Peripheral Arterial Interventions

Interventional Cardiology Review ◽

10.15420/icr.2016:8:2 ◽

2016 ◽

Vol 11 (2) ◽

pp. 128

Author(s):

Brock Cookman ◽

Suhail Allaqaband ◽

Tonga Nfor ◽

◽

...

Keyword(s):

Strong Relationship ◽

Ageing Population ◽

Peripheral Vascular ◽

Endovascular Interventions ◽

Cardiovascular Morbidity And Mortality ◽

Vascular Beds ◽

Peripheral Arterial ◽

Peripheral Artery Diseases ◽

Broad Understanding

With an ageing population, the burden of peripheral artery diseases (PADs) is increasing. The treatment of these diseases has largely been performed by interventional radiologists, vascular surgeons and interventional cardiologists. Due to the strong relationship between PAD and overall cardiovascular morbidity and mortality, cardiologists need to play a greater role in the management of PAD. The physician who cares for the patient with peripheral vascular disease should have a broad understanding of atherosclerotic disease involving all vascular beds. Endovascular interventions play a major role in relieving symptoms and reducing morbidity related to PAD, but long-term optimal medical treatment is an essential determinant of prognosis. This paper reviews current endovascular/percutaneous interventions for PAD.

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