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Selected Works

2011

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Articles 1 - 30 of 519

Full-Text Articles in Engineering

Identification And Thermochemical Analysis Of High-Lignin Feedstocks For Biofuel And Biochemical Production, Venugopal Mendu, Anne Harman-Ware, Mark Crocker, Jungho Jae, Jozsef Stork, Samuel Morton, Andrew Placido, George Huber, Seth Debolt Dec 2015

Identification And Thermochemical Analysis Of High-Lignin Feedstocks For Biofuel And Biochemical Production, Venugopal Mendu, Anne Harman-Ware, Mark Crocker, Jungho Jae, Jozsef Stork, Samuel Morton, Andrew Placido, George Huber, Seth Debolt

Samuel A Morton

Background - Lignin is a highly abundant biopolymer synthesized by plants as a complex component of plant secondary cell walls. Efforts to utilize lignin-based bioproducts are needed. Results - Herein we identify and characterize the composition and pyrolytic deconstruction characteristics of high-lignin feedstocks. Feedstocks displaying the highest levels of lignin were identified as drupe endocarp biomass arising as agricultural waste from horticultural crops. By performing pyrolysis coupled to gas chromatography-mass spectrometry, we characterized lignin-derived deconstruction products from endocarp biomass and compared these with switchgrass. By comparing individual pyrolytic products, we document higher amounts of acetic acid, 1-hydroxy-2-propanone, acetone and furfural …

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A Review Of Baobab (Adansonia Digitata) Products: Effect Of Processing Techniques, Medicinal Properties And Uses, Donatien Kabore, Hagrétou Sawadogo-Lingani, Bréhima Diawara, Clarise Compaoré, Mamoudou H. Dicko Prof., Mogens Jacobsen Dec 2011

A Review Of Baobab (Adansonia Digitata) Products: Effect Of Processing Techniques, Medicinal Properties And Uses, Donatien Kabore, Hagrétou Sawadogo-Lingani, Bréhima Diawara, Clarise Compaoré, Mamoudou H. Dicko Prof., Mogens Jacobsen

Pr. Mamoudou H. DICKO, PhD

A general literature review including the effect of processing techniques, medicinal value and uses of baobab tree is reported in this manuscript. Baobab tree has multi-purpose uses, as it produces food and non-food products such as medicines, fuel, timber, fodder. Every part of the baobab tree is reported to be useful. The seeds, leaves, roots, flowers, fruit pulp and bark of baobab are edible. Baobab leaves are used in the preparation of soup. Seeds are used as a thickening agent in soups, but they can be fermented and used as a flavouring agent or roasted and eaten as snacks. The …

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Predicted And Observed Behaviour Of Soft Clay Foundations Stabilised With Vertical Drains, Buddhima Indraratna, Wadud Salim, I W Redana Dec 2011

Predicted And Observed Behaviour Of Soft Clay Foundations Stabilised With Vertical Drains, Buddhima Indraratna, Wadud Salim, I W Redana

Buddhima Indraratna

A novel plane strain approach is introduced to model the behaviour of embankment foundations on soft clay stabilised with vertical drains, where the classical axisymmetric solutions are converted to an equivalent plane strain model, incorporating the effects of smear and well resistance. This paper describes the behaviour of an embankment stabilised with vertical drains, where a specific case history is selected from Malaysia. The consolidation of soft clay is modelled on the basis of the modified Cam-clay. The settlement behaviour at various stages of embankment loading is analysed using the finite element technique, and the numerical results are compared with …

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Effects Of Tsunami On Coastal Ground Conditions And Appropriate Measures For Rail Track Rehabilitation, Buddhima Indraratna, Mohammad Hadi Khabbaz, A. Puswewala, W. Bandara Dec 2011

Effects Of Tsunami On Coastal Ground Conditions And Appropriate Measures For Rail Track Rehabilitation, Buddhima Indraratna, Mohammad Hadi Khabbaz, A. Puswewala, W. Bandara

Buddhima Indraratna

On boxing day, 26 December 2004, the largest earthquake for more than 4 decades, (magnitude 9.0) occurred between the Australian and Eurasian plates in the Indian Ocean (along the overly stressed Sunda trench) to the west of Aceh Province (Northern Sumatra). The quake triggered a series of waves that increased in height rapidly close to the shore (tsunami) spreading thousands of kilometers across the Bay of Bengal. In the Eastern and Southern coastal belt of Sri Lanka, the floodwaters reached almost 1 km inland, causing extensive damage to infrastructure and fatalities of unprecedented proportions. Widespread destruction included several kilometres of …

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Experimental Investigations Into Subballast Filtrations Behaviour Under Cyclic Conditions, Laricar Dominic Ortega Trani, Buddhima Indraratna Dec 2011

Experimental Investigations Into Subballast Filtrations Behaviour Under Cyclic Conditions, Laricar Dominic Ortega Trani, Buddhima Indraratna

Buddhima Indraratna

In rail track environments the loading system is cyclic unlike the monotonic seepage force that usually occurs in embankment dams. The mechanisms of filtration, interface behaviour and time-dependent changes of the drainage and filtration properties occurring within the filter medium require further research to improve the design guidelines. A novel cyclic process simulation filtration apparatus was designed and commissioned at the University of Wollongong, and a standard testing procedure was established. The test apparatus was designed to simulate heavy haul train operations. Key parameters that influence the change in porosity and pore water pressure within the sub ballast layer under …

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Long-Term Performance Of A Permeable Reactive Barrier In Acid Sulphate Soil Terrain, Gyanendra Regmi, Buddhima Indraratna, Long Nghiem Dec 2011

Long-Term Performance Of A Permeable Reactive Barrier In Acid Sulphate Soil Terrain, Gyanendra Regmi, Buddhima Indraratna, Long Nghiem

Buddhima Indraratna

Deep drainage technique utilised for flood mitigation in low-land coastal areas of Australia during the late 1960s has resulted in the generation of sulphuric acid in soil by the oxidation of pyritic materials. Further degradation of the subsurface environment with widespread contamination of the underlying soil and groundwater presents a major and challenging environmental issue in acid sulphate soil (ASS) terrains. Although several ASS remediation techniques recently implemented in the floodplain of Southeast Australia including operation of gates, tidal buffering and lime injections could significantly control the pyrite oxidation, they could not improve the long-term water quality. More recently, permeable …

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Soft Soils Improved By Prefabricated Vertical Drains: Performance And Prediction, Buddhima Indraratna, Cholachat Rujikiatkamjorn, V Wijeyakulasuriya, G Mcintosh, R Kelly Dec 2011

Soft Soils Improved By Prefabricated Vertical Drains: Performance And Prediction, Buddhima Indraratna, Cholachat Rujikiatkamjorn, V Wijeyakulasuriya, G Mcintosh, R Kelly

Buddhima Indraratna

The use of prefabricated vertical drains with preloading is now common practice and is proving to be one of the most effective ground improvement techniques known. The factors affecting its performance, such as the smear zone, the drain influence zone, and drain unsaturation, are discussed in this paper. In order to evaluate these effects a large scale consolidation test was conducted and it was found that the proposed Cavity Expansion Theory could be used to predict the characteristics of the smear zone based on the soil properties available. Moreover, the procedure for converting an equivalent 2-D plane strain multi-drain analysis …

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Geo-Environmental Approaches For The Remediation Of Acid Sulphate Soil In Low-Lying Floodplains, Buddhima Indraratna, Gyanendra Regmi, Long Nghiem, Alexandra N. Golab Dec 2011

Geo-Environmental Approaches For The Remediation Of Acid Sulphate Soil In Low-Lying Floodplains, Buddhima Indraratna, Gyanendra Regmi, Long Nghiem, Alexandra N. Golab

Buddhima Indraratna

Acidity generated from the oxidation of pyrite and other sulphidic compounds that exist at shallow depths in acid sulphate soils (ASS) presents a challenging environmental problem in coastal Australia. The generated acidic groundwater can adversely impact coastal ecosystems, aquaculture and agriculture. Groundwater manipulation using weirs and modified floodgates in creeks and flood mitigation drains in ASS-affected farmland, which has been practiced for over a decade for preventing pyrite oxidation, is not effective in low-lying floodplains due to the high risk of flooding. In this paper, the authors present an overview of their experience in coastal Australia, a critical evaluation of …

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A Study Of The Strength Of Lime Treated Soft Clays, Martin D. Liu, Stephen Pemberton, Buddhima Indraratna Dec 2011

A Study Of The Strength Of Lime Treated Soft Clays, Martin D. Liu, Stephen Pemberton, Buddhima Indraratna

Buddhima Indraratna

In this paper, a comprehensive study of the strength of lime treated soft clays is made. There are three major factors that affect the strength of the soils; they are the lime content, curing time, and curing temperature. The variations of soil strengths with the three factors are analysed and quantified via proposed empirical equations. These equations are verified against experimental data. Finally, a general strength criterion, unifying the influence of all the three factors into a single equation, is proposed. The capacity of the general equation is also demonstrated. It is seen that the proposed strength equations can provide …

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Tidal Forcing Groundwater Dynamics In A Restored Coastal Wetland: Implications Of Saline Intrusion, William Glamore, Buddhima Indraratna Dec 2011

Tidal Forcing Groundwater Dynamics In A Restored Coastal Wetland: Implications Of Saline Intrusion, William Glamore, Buddhima Indraratna

Buddhima Indraratna

Tidal restoration projects are currently being undertaken throughout coastal Australia without a full understanding of the influence of tidal forcing on groundwater salinity. To determine the impact of restoring tidal flows on groundwater salinity levels, field investigations were undertaken at a study site near Berry, New South Wales. Fluctuations in groundwater and surface water chemistry (soluble chloride, pH, electrical conductivity) and hydrodynamics were measured over a 12 week period using multilevel piezometers and submersible data loggers spaced at discrete distances from a flood mitigation drain. Additional parameters, including saturated hydraulic conductivity (Ksat), were undertaken to determine baseline conditions and to …

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The Behaviour Of Ballasted Track Foundations: Track Drainage And Geosynthetic Reinforcement, Buddhima Indraratna, Sanjay Nimbalkar, Nayoma Chulani Tennakoon Dec 2011

The Behaviour Of Ballasted Track Foundations: Track Drainage And Geosynthetic Reinforcement, Buddhima Indraratna, Sanjay Nimbalkar, Nayoma Chulani Tennakoon

Buddhima Indraratna

Ballasted Rail tracks are widely used throughout the world due to its resiliency to the repeated wheel loads, low construction cost and ease of maintenance. However, the ballast layer needs periodic maintenance due to its deformation and degradation associated with particle breakage and fouling. A proper understanding of the contamination due to various types of fines and its implications on track drainage is a pre-requisite for effective implementation of track maintenance operations. A new parameter Void Contaminant Index (VCI) can accurately assess the contamination as it includes the effect of void ratio, specific gravity and gradation of ballast and fouling …

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Critical Review On Shear Strength Models For Soil-Infilled Joints, David Oliveira, Buddhima Indraratna, Jan Anton Nemcik Dec 2011

Critical Review On Shear Strength Models For Soil-Infilled Joints, David Oliveira, Buddhima Indraratna, Jan Anton Nemcik

Buddhima Indraratna

An infilled rock joint is likely to be the weakest plane in a rock mass. The presence of infill material within the joint significantly reduces the friction of the discontinuity boundaries (i.e. rock to rock contact of the joint walls). The thicker the infill, the smaller the shear strength of the rock joint. Once the infill reaches a critical thickness, the infill material governs the overall shear strength, and the joint walls (rock) play no significant role. Several models have been proposed to predict the peak shear strength of soil-infilled joints under both constant normal load (CNL) and constant normal …

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Occurrence And Consequences Of Acid Sulphate Soils And Methods Of Site Remediation, Alexandra N. Golab, Buddhima Indraratna Dec 2011

Occurrence And Consequences Of Acid Sulphate Soils And Methods Of Site Remediation, Alexandra N. Golab, Buddhima Indraratna

Buddhima Indraratna

The oxidation of sulphides in acid sulphate soils (ASS) causes the acidification of many Australian coastal river systems. The acidity negatively impacts upon coastal ecosystems, aquaculture, agriculture and concrete and steel infrastructure. In the low-lying floodplains, relatively deep surface drains fitted with one-way floodgates lower the watertable, thereby exposing the sulphidic minerals to oxidation. On the Broughton Creek floodplain in SE Australia, four distinct remediation strategies have been developed to tackle the issue of acidification by ASS: (i) simple V-notch weirs that raise the level of the watertable surrounding the drains thereby submerging the pyrite and preventing the further formation …

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Modeling Of Acid Generation In Pyritic Estuarine Soils, Buddhima Indraratna, Bruce G Blunden Dec 2011

Modeling Of Acid Generation In Pyritic Estuarine Soils, Buddhima Indraratna, Bruce G Blunden

Buddhima Indraratna

The effective management of acid sulfate or pyritic soils is a major issue for many coastal regions in Australia. Drainage and subsequent aeration of potential acid sulfate soils often leads to pyrite oxidation and the acidification of the soil and groundwater. A numerical model has been developed to calculate the rate and magnitude of pyrite oxidation in acid sulfate soils, and the distribution of oxidation products such as H+, SO4 2- and Fe3+ within the soil profile. The pyrite oxidation model includes vertical diffusion of oxygen from the atmosphere through soil macropores, lateral diffusion of dissolved oxygen from the macropores …

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Development Of Sediment-Infilled Rock Joint Models And Implications On Rockmass Stability, Buddhima Indraratna, Wuditha N. Premadasa, David Oliveira, H S. Welideniya Dec 2011

Development Of Sediment-Infilled Rock Joint Models And Implications On Rockmass Stability, Buddhima Indraratna, Wuditha N. Premadasa, David Oliveira, H S. Welideniya

Buddhima Indraratna

Soil-infi lled discontinuities adversely infl uence the stability of rockmass, because, the infi ll materials especially when saturated, drastically reduce the shear strength. The angle of shearing resistance of a discontinuity decreases signifi cantly for increasing infi ll thickness. Once it reaches a critical thickness, the shear strength of the discontinuity will be governed only by the infi ll material and the rock-walls effect becomes negligible. Owing to the lack of research on the shear behavior of infi lled rock joints, it has been common practice to assume that the shear strength of the joint is that of the infi …

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Tidal-Forcing Groundwater Dynamics In A Restored Coastal Wetland: Implications Of Saline Intrusion, William Glamore, Buddhima Indraratna Dec 2011

Tidal-Forcing Groundwater Dynamics In A Restored Coastal Wetland: Implications Of Saline Intrusion, William Glamore, Buddhima Indraratna

Buddhima Indraratna

Tidal restoration projects are currently being undertaken throughout coastal Australia without a full understanding of the influence of tidal forcing on groundwater salinity. To determine the impact of restoring tidal flows on groundwater salinity levels, field investigations were undertaken at a study site near Berry, New South Wales. Fluctuations in groundwater and surface water chemistry (soluble chloride, pH, electrical conductivity) and hydrodynamics were measured over a 12 week period using multilevel piezometers and submersible data loggers spaced at discrete distances from a flood mitigation drain. Additional parameters, including saturated hydraulic conductivity (Ksat), were undertaken to determine baseline conditions and to …

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Dem Simulation Of Effect Of Confining Pressure On Ballast Behaviour, P K. Thakur, Buddhima Indraratna, Jayan Sylaja J S Vinod Dec 2011

Dem Simulation Of Effect Of Confining Pressure On Ballast Behaviour, P K. Thakur, Buddhima Indraratna, Jayan Sylaja J S Vinod

Buddhima Indraratna

In this paper, an attempt has been made to investigate the influence of confining pressure on deformation and degradation behaviourof railway ballast using the Discrete Element Method (DEM). A novel approach has been employed to model the two dimensionalprojection of field size ballast particles as cluster of bonded particles. Bonded particles are held together by a bond, and debonding isconsidered as particle breakage. A series of cyclic loading simulations using DEM were carried out on an assembly of angular ballast particles at different confining pressures (10 kPa to 240 kPa). The results highlight that the development of axial strain during …

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State Of The Art Large Scale Testing Of Ballast, Buddhima Indraratna, D J Ionescu Dec 2011

State Of The Art Large Scale Testing Of Ballast, Buddhima Indraratna, D J Ionescu

Buddhima Indraratna

Poor performance of rail roads is often associated with the loss of cross level, track profile and track alignment. The initial as placed condition of ballast and its engineering behaviour govern the stability and the performance of a railway track. The load bearing capacity of ballast and its short and long term degradation characteristics can only be studied using large scale testing equipment, because the conventional geotechnical equipment cannot accommodate the relatively large aggregates. Large-scale testing provides specific geotechnical knowledge on the shear strength and particle degradation of ballast, in relation to the particle size distribution. The influence of principal …

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Modeling Of Bolted Joint Behaviour Under Constant Normal Stiffness Conditions - Laboratory Study, Buddhima Indraratna, Najdat I. Aziz, A Dey Dec 2011

Modeling Of Bolted Joint Behaviour Under Constant Normal Stiffness Conditions - Laboratory Study, Buddhima Indraratna, Najdat I. Aziz, A Dey

Buddhima Indraratna

The shear behaviour of grouted joints has been studied in the recent past using the conventional direct shear apparatus, where the normal load on the joint plane is kept constant during testing. The Constant Normal Stiffness (CNS) condition is adopted in this study of shear behaviour of bolted joints, as the CNS condition represents a better approximation of the deformation behaviour of grouted joints in underground excavations as compared to the conventional Constant Normal Load (CNL) condition. A series of tests were conducted to study the behaviour of these stabilised joints under constant normal stiffness condition at an initial normal …

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Treatment Of Acidic Groundwater In Acid Sulfate Soil Terrain Using Recycled Concrete: Column Experiments, Gyanendra Regmi, Buddhima Indraratna, Long Nghiem, A. Golab, B Guru Prasad Dec 2011

Treatment Of Acidic Groundwater In Acid Sulfate Soil Terrain Using Recycled Concrete: Column Experiments, Gyanendra Regmi, Buddhima Indraratna, Long Nghiem, A. Golab, B Guru Prasad

Buddhima Indraratna

Acidic groundwater generated from pyrite oxidation in acid sulfate (AS) soil is a major geoenvironmental problem in Australia. This study aims to evaluate recycled concrete as a reactive material in permeable reactive barriers (PRBs) for the remediation of acidic groundwater in low-lying AS soil floodplains. Laboratory experiments were systematically conducted to investigate the acid neutralization behavior of recycled concrete and its potential to remove dissolved Al and Fe. The results confirmed that recycled concrete could effectively treat acidic groundwater from an AS soil terrain, resulting in near neutral effluent over a long period with complete removal of Al and Fe. …

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Numerical Prediction Of Vadose Zone Behaviour Influenced By Vegetation, Buddhima Indraratna, Behzad Fatahi, Mohammad Hadi Khabbaz Dec 2011

Numerical Prediction Of Vadose Zone Behaviour Influenced By Vegetation, Buddhima Indraratna, Behzad Fatahi, Mohammad Hadi Khabbaz

Buddhima Indraratna

Bioengineering aspects of native vegetation are currently, and rapidly, being evolved to improve soil stiffness, slope stabilisation, and erosion control. Apart from the reinforcement effect, tree roots establish sufficient matric suction to increase the shear strength and stiffness of the soil. This paper looks at the way, vegetation influences soil matric suction, shrinkage, and ground settlement. A mathematical model for the rate of root water uptake that considers ground conditions, type of vegetation and climatic parameters, has been developed. Based on this proposed model, the distribution of moisture and the matric suction profile adjacent to the tree are numerically analysed. …

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Design Procedure For Vertical Drains Considering A Linear Variation Of Lateral Permeability Within The Smear Zone, Cholachat Rujikiatkamjorn, Buddhima Indraratna Dec 2011

Design Procedure For Vertical Drains Considering A Linear Variation Of Lateral Permeability Within The Smear Zone, Cholachat Rujikiatkamjorn, Buddhima Indraratna

Buddhima Indraratna

A system of vertical drains with surcharge preloading is an effective method for promoting radial drainage and accelerated soil consolidation. This study presents a procedure for the design of vertical drains that significantly extends the previous technique proposed by the authors to include: (i) a linear reduction of lateral permeability in the smear zone, (ii) the effect of overlapping smear zones in a closely spaced drain network, and (iii) the gain in undrained shear strength due to consolidation. Design examples are provided for both single stage and multi-stage embankment construction demonstrating the convenient use of the proposed solutions in practical …

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Modelling Of Soft Ground Consolidation Via Combined Surcharge And Vacuum Preloading, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Ali Ghandeharioon Dec 2011

Modelling Of Soft Ground Consolidation Via Combined Surcharge And Vacuum Preloading, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Ali Ghandeharioon

Buddhima Indraratna

A system of vertical drains combined with vacuum and surcharge preloading is an effective approach for promoting radial flow to accelerate soil consolidation. When a higher load is required to meet the desired rate of settlement and the cost of surcharge is also significant, the application of vacuum pressure with reduced surcharge loading can be used. The equivalent 2-D plane strain solution for multi-drain analysis is described with the inclusion of the effects of vacuum pressure and smear zone caused by mandrel driven vertical drains. A large-scale radial consolidometer is employed to determine the extent of the smear zone and …

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Physical And Chemical Ground Improvement For Sustainable Transportation Infrastructure Under Cyclic Loads, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Jayan S. Vinod, Sanjay Nimbalkar Dec 2011

Physical And Chemical Ground Improvement For Sustainable Transportation Infrastructure Under Cyclic Loads, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Jayan S. Vinod, Sanjay Nimbalkar

Buddhima Indraratna

Railways form one of the major worldwide transportation networks and they continue to provide quick and safe public and freight transportation. In order to compete with other modes of transportation and to meet the ever growing demand of public and freight transport, railway industries face challenges to improve their efficiency and decrease the costs of maintenance and infrastructure. Large cyclic loading from heavy haul and passenger trains often leads to progressive deterioration of the track. The excessive deformations and degradations of the ballast layer and unacceptable differential settlement or pumping of underlying soft and compressible subgrade soils necessitate frequent costly …

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Evaluating Waste Concrete For The Treatment Of Acid Sulphate Soil Groundwater From Coastal Floodplains, Gyanendra Regmi, Buddhima Indraratna, Long Nghiem, Laura Banasiak Dec 2011

Evaluating Waste Concrete For The Treatment Of Acid Sulphate Soil Groundwater From Coastal Floodplains, Gyanendra Regmi, Buddhima Indraratna, Long Nghiem, Laura Banasiak

Buddhima Indraratna

The treatment of acidic groundwater generated from acid sulphate soil (ASS) terrain is a challenging environmental issue in coastal floodplains of Australia. In this study, a laboratory column experiment was conducted to assess the performance of waste concrete for treating the acidic groundwater leachate from ASS terrain of the Shoalhaven region of NSW. The groundwater was highly acidic (pH of 2.5–3.5) and contained elevated concentrations of iron (10–90 mg/L) and aluminium (30–45 mg/L). Passage of the acidic groundwater through the column filled with waste concrete resulted in a significant improvement in water quality. Reduction in the concentration of iron and …

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Consolidation Of Ground With Partially Penetrated Pvds Combined With Vacuum Preloading, Xueyu Geng, Buddhima Indraratna, Cholachat Rujikiatkamjorn Dec 2011

Consolidation Of Ground With Partially Penetrated Pvds Combined With Vacuum Preloading, Xueyu Geng, Buddhima Indraratna, Cholachat Rujikiatkamjorn

Buddhima Indraratna

Partially penetrating prefabricated vertical drain (PVDs) with a combined surcharge and vacuum preloading are considered in this paper. The analysis results can be used in cases where the soft soil clay is too deep and not economical to be penetrated to full depth, or the surcharge preloading is too small to justify full penetration of soft clay layer or the vacuum pressure can be lost, which is caused by the permeability of the bottom of the clay for the fully penetrated drain etc.. In this model, a virtual vertical drain is assumed to reflect the real three-dimensional seepage in the …

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Stress Analysis In Failed Roof At A Longwall Face, Jan Anton Nemcik, Ian Porter, Buddhima Indraratna Dec 2011

Stress Analysis In Failed Roof At A Longwall Face, Jan Anton Nemcik, Ian Porter, Buddhima Indraratna

Buddhima Indraratna

This paper presents a conceptual work on roof failure mechanisms at a longwall coal mining face based on a multiple sliding block model. Underground observations of the caved roof strata at the longwall face indicate that many types of fracture exist and that two are dominant. In response to roof convergence close to the goaf, the stratified ground flexes resulting in shear failure along the weak bedding planes that are present in sedimentary strata, while sub-vertical fractures form just ahead of the longwall face in response to the mining induced stress state. . These mining induced fractures usually occur at …

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Coupled Air-Water Flow Through Fractured Sandstones, Buddhima Indraratna, P Ranjith Dec 2011

Coupled Air-Water Flow Through Fractured Sandstones, Buddhima Indraratna, P Ranjith

Buddhima Indraratna

In two-phase flow within a rock mass, where both air and water phases flow together, the accurate flow measurement of each individual phase is important in numerical analyses. The increased quantity of water phase decreases the relative permeability of the air phase, and vice versa. The relative permeability is important to analyse the risk of groundwater inundation and gas outbursts particularly in underground excavations. Two-phase flow (i.e., water and air) behaviour through naturally and artificially fractured standard rock cores is investigated using the high-pressure triaxial equipment developed by the authors. Findings of this study show that the individual flow rate …

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Analytical Solutions For A Single Vertical Drain With Time-Dependent Vacuum Combined Surcharge Preloading In Membrane And Membraneless Systems, Xueyu Geng, Buddhima Indraratna, Cholachat Rujikiatkamjorn Dec 2011

Analytical Solutions For A Single Vertical Drain With Time-Dependent Vacuum Combined Surcharge Preloading In Membrane And Membraneless Systems, Xueyu Geng, Buddhima Indraratna, Cholachat Rujikiatkamjorn

Buddhima Indraratna

Vertical drains combined with vacuum pressure and surcharge preloading are widely used to accelerate the consolidation process of soft clay in order to decrease the pore pressure as well as to increase the effective stress. Currently there are two types of vacuum preloading systems commercially available; (a) membrane system with an airtight membrane over the drainage layer and, (b) membraneless system where a vacuum system is connected to individual drain. Their effectiveness varies from site to site depending on the type of soil treated and the characteristics of the drain-vacuum system. This study presents the analytical solutions of vertical drains …

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Experimental And Numerical Modeling Of Shear Behaviour Of Rock Joints, Buddhima Indraratna, A Haque Dec 2011

Experimental And Numerical Modeling Of Shear Behaviour Of Rock Joints, Buddhima Indraratna, A Haque

Buddhima Indraratna

The shear behaviour of soft rock joints is investigated in laboratory under both Constant Normal Load (CNL) and Constant Normal Stiffness (CNS) conditions. The laboratory behaviour is modelled numerically using the Universal Distinct Element Code (UDEC). The predicted shear stress, normal stress and dilation behaviour with shear displacements are compared with the laboratory results. It is observed that UDEC can predict the peak shear stress of unfilled joints under CNS, however, it overestimates the joint dilation as well as the normal stress. The maximum peak shear stress in UDEC is attained at a greater shear displacement in contrast to the …

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