ORCID Profile
0000-0002-1009-0447
Current Organisation
Queen's University
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Publisher: Thomas Telford Ltd.
Date: 12-2020
Abstract: Desiccation of geosynthetic clay liners (GCLs) in composite lining systems is investigated experimentally. Field conditions similar to those encountered in brine ponds (high surface temperature and low overburden pressure of 20 kPa) are simulated in two soil columns. The GCL is first allowed to hydrate from a sandy subsoil under isothermal conditions (44 days), then subjected to a thermal gradient applied through a heat source (78°C) on top of the geomembrane (39 days). Changes in water content, temperature of subsoil and movement of the surface during hydration and heating stages are measured. A sharp rise in moisture content is observed in the upper region of the subsoil immediately after the start of heating, which shortly dissipates. After 39 days of heating, the bentonite in the tested GCLs is dehydrated to around 8% gravimetric water content, down from over 100% after hydration. In addition, more than 3 mm of shrinkage of bentonite in the vertical direction is recorded. X-ray imaging after the tests reveals extensive desiccation cracking of bentonite. The study has confirmed the existence of a significant risk of desiccation of GCLs under thermal gradients and has generated data that are useful for validating models used for the prediction of GCL behaviour.
Publisher: Elsevier BV
Date: 12-2020
Publisher: Springer International Publishing
Date: 2018
Publisher: American Society of Civil Engineers (ASCE)
Date: 07-2019
Publisher: Thomas Telford Ltd.
Date: 10-2020
Abstract: A new approach is presented to obtain the water retention curve of a geosynthetic clay liner (GCL) on the wetting path (i.e. when it is hydrating). This approach is based on a back-analysis process using data from a hydration test. The back-analysis method was validated by comparing it to conventional experimental measurement techniques such as vapour equilibrium, chilled-mirror dew point and osmotic techniques as well as published data. This approach is shown to be a viable alternative to quickly identify the retention properties of a GCL on the wetting path.
Publisher: Elsevier BV
Date: 02-2019
DOI: 10.1016/J.JENVMAN.2018.07.092
Abstract: A new vapour intrusion contaminant transport model was designed specifically to allow an assessment of the impact of a hydrocarbon fuel spill on air quality in cold region buildings. The model is applied to a recent situation in Antarctica, where a diesel spill impacted the construction of a new building. For the first time, this model allows consideration of the diffusive resistance of different vapour barrier to the transport of hydrocarbons into the building and an assessment of the effectiveness of different products. Site specific indoor air criteria are derived. Five scenarios are modelled at field temperatures: (1) build on current contaminated site (2) excavate contaminated soil, backfill with clean soil and assess impact of residual contamination (3) excavate and backfill with remediated (biopile) soil (4) backfill with remediated soil and assess impact of residual contamination (5) backfill with remediated soil and assess impact of a potential future fuel spill. Two different vapour barriers, a co-extruded ethylene vinyl alcohol (EVOH) geomembrane (VB1) and a linear low-density (LLDPE) geomembrane (VB2), are investigated for each scenario and compared to a base case with no vapour barrier, providing quantifiable evidence of the benefit of installing an engineered vapour barrier Contaminant concentrations were below regulatory limits for Scenarios (2-5) with VB1 and air exchange in the building. For all scenarios, the EVOH geomembrane (VB1) was consistently superior at reducing vapour transport into the building indoor air space over the LLDPE geomembrane (VB2) and no vapour barrier. The risk mitigation measures developed for this contaminated Antarctic site may be relevant for other buildings in cold regions.
Publisher: Elsevier BV
Date: 12-2020
Publisher: Wiley
Date: 04-1993
Publisher: Elsevier BV
Date: 04-2019
Publisher: Canadian Science Publishing
Date: 08-2017
Abstract: 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.
Publisher: Thomas Telford Ltd.
Date: 11-2019
Abstract: The transfer of embankment stresses towards pile heads in piled embankments is attributed to the mechanism known as soil arching. Three-dimensional physical models of piled embankments were built to simulate this mechanism. The progressive settlement of subsoil beneath an embankment was modelled and paused at increments of displacements to allow synchrotron X-ray computed tomography to be performed on the models. Image correlation techniques were then applied to the reconstructed volumes to obtain evolving three-dimensional displacement and strain fields. The strain fields show localised (shear bands) and diffuse failure modes occurring above pile heads within the embankment fill. These failure surfaces are seen to progressively develop as the subsoil undergoes settlement. The displacement fields also show the formation of a plane of equal settlement developing at a height above the pile heads, known as the critical height. The critical height is dependent on the height at which the failure surfaces propagate into the embankment fill, and a method is proposed to calculate the maximum height of failure surfaces based on the observed kinematics. The full-field kinematics provide fundamental insight into the soil arching mechanism that develops within piled embankments.
Publisher: Elsevier BV
Date: 10-2016
Publisher: Elsevier BV
Date: 1988
Publisher: Elsevier BV
Date: 10-2016
Publisher: Canadian Science Publishing
Date: 08-2020
Abstract: An Antarctic biopile using a composite liner (high-density polyethylene geomembrane (GMB) over a geosynthetic clay liner (GCL)) was constructed on a coarse granular subgrade to contain hydrocarbon-contaminated soil and leachate. The soil was remediated after 4 years and the biopile was decommissioned. The liner was exhumed to assess the properties and performance of the GMB and GCL. There was no significant change in the GMB index properties. Although cobbles and coarse gravel of the subgrade had left indentations in the GMB, implying tensile strains that could impact long-term performance, there were no holes. There was significant variability in the hydration of the GCL (from 10% to 220%) and in the underlying subgrade soil water content (from 5% to 30%). This reflects the complexity of the subgrade and groundwater flow in the Antarctic environment. The exhumed GCL specimens had low hydraulic conductivity (1 × 10 −11 to 7 × 10 −11 m/s) at 13 kPa. Soil s les from below the composite liner showed no detectable hydrocarbons and confirmed no migration through the barrier. It is concluded that the composite barrier contained the leachate and biopile soil over the 4 years in service in the extreme Antarctic conditions.
Publisher: Canadian Science Publishing
Date: 02-2023
Abstract: This study demonstrates the change in porosity of permeable reactive barrier (PRB) material when it reacts with acidic flow. The laboratory column test data obtained over 9 months prove that the porosity of a granular limestone assembly decreases significantly due to bio-geochemical clogging caused by a continuous flow of acidic groundwater. The variations in pH, the pressure measurements, ion concentrations, and the results from X-ray diffraction suggest that clogging at the outlet of the column is much less than at the inlet. About 57% of the total reduction in porosity of the column is attributed to chemical clogging, while the remainder is mainly due to biological clogging. In this paper, a mathematical approach is proposed to estimate the reduction of reactive surface area based on changes in the pore volume. These proposed equations suggest that at the end of experimentation, the dissolution of calcite and bio-geochemical clogging can reduce the total surface area of limestone aggregates by more than 70%. The rigorous approach presented in this paper to determine the dominant clogging component within a granular filter at a given time is vital in estimating the longevity of a PRB and for planning its maintenance.
Publisher: American Society of Civil Engineers (ASCE)
Date: 05-2020
Publisher: Elsevier BV
Date: 08-2017
Publisher: American Society of Civil Engineers (ASCE)
Date: 12-2000
Publisher: Canadian Science Publishing
Date: 06-2018
Abstract: For geosynthetic reinforced column supported embankments (GRCSE) supporting a high embankment, lateral forces associated with lateral sliding and embankment stability often govern the acceptability of a given design under serviceability conditions. Frequently, the complex soil–structure–geosynthetic interaction, the size, and the three-dimensional nature of a GRCSE necessitate the use of numerical analysis to assess embankment performance relative to serviceability criteria. However, traditional finite element method techniques used to model serviceability behaviour are limited in their ability to model the geotechnical mechanisms associated with column installation, equilibration, and group installation effects. These installation effects are examined herein based on a GRCSE field case study located in Melbourne, Australia, that has been extensively instrumented. The role that these installation effects have on the performance of the GRCSE is highlighted and the behaviour of the columns supporting the embankment is emphasized. It is shown that cracking of the unreinforced columns supporting the embankment is likely inevitable and that the reduction of lateral resistance provided by the columns should be accounted for in design. The suitability of various numerical approaches currently used in design to model the columns supporting the GRCSE, and the embankment itself, are discussed and recommendations are made.
No related grants have been discovered for R. Kerry Rowe.