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Full-Text Articles in Engineering
Shear Behaviour Of Rock Joints Under Cyclic Loading, Buddhima Indraratna, Ali Mirzaghorbanali, David Oliveira, Wuditha N. Premadasa
Shear Behaviour Of Rock Joints Under Cyclic Loading, Buddhima Indraratna, Ali Mirzaghorbanali, David Oliveira, Wuditha N. Premadasa
Buddhima Indraratna
For the design of civil and mining engineering geo-structures, it is often necessary to investigate the behaviour and the role of discontinuities on the rock mass performance. In many cases, failure is governed by the shear behaviour of discontinuities in excavations. In this context, evaluation of the effects of small repetitive earthquakes on the shear strength parameters of rock joints especially in tunnels and dam foundations is also important. This paper presents the results of a systematic study carried out on the cyclic shear behaviour of artificial rock joints under constant normal stiffness (CNS) conditions, as many of the previous …
A Laboratory Study Of Railway Ballast Behaviour Under Various Fouling Degree, Cholachat Rujikiatkamjorn, Buddhima Indraratna, Ngoc Trung Ngo, Matthew Coop
A Laboratory Study Of Railway Ballast Behaviour Under Various Fouling Degree, Cholachat Rujikiatkamjorn, Buddhima Indraratna, Ngoc Trung Ngo, Matthew Coop
Buddhima Indraratna
This paper presents a laboratory study of interface behavior between ballast and geogrid under various degree of fouling by coal fines. The stress-displacement behaviour of fresh and fouled ballast with geogrid was investigated through a series of large-scale direct shear tests where the fouling degree varied from 0% to 95% Void Contamination Index (VCI), at normal stresses ranging from 15kPa to 75kPa. The results showed that geogrid enhances the shear strength and increases apparent angle of shearing resistance, while only slightly reduces the vertical displacement of the composite geogrid-ballast system. However, when ballast was contaminated by coal fines, the influences …
Behaviour Of Clay-Fouled Ballast Under Drained Triaxial Testing, Buddhima Indraratna, Nayoma C. Tennakoon, Sanjay Shrawan Nimbalkar, Cholachat Rujikiatkamjorn
Behaviour Of Clay-Fouled Ballast Under Drained Triaxial Testing, Buddhima Indraratna, Nayoma C. Tennakoon, Sanjay Shrawan Nimbalkar, Cholachat Rujikiatkamjorn
Buddhima Indraratna
Contamination or fouling of rail ballast with external fines, including slurried and pumped subgrade material (e.g. clay and silt), is one of the primary reasons for track deterioration. Fouling causes differential settlement of the track, and also decreases the load-bearing capacity, owing to the reduction in the friction angle of the granular assembly. In certain circumstances, fouled ballast needs to be cleaned or replaced to maintain the desired track stiffness, load-bearing capacity and track alignment, all of which influence safety. This paper presents and discusses the results of a series of large-scale triaxial tests conducted on latite basalt, a rail …
Dem Simulation Of The Behaviour Of Geogrid Stabilised Ballast Fouled With Coal, Ngoc Trung Ngo, Buddhima Indraratna, Cholachat Rujikiatkamjorn
Dem Simulation Of The Behaviour Of Geogrid Stabilised Ballast Fouled With Coal, Ngoc Trung Ngo, Buddhima Indraratna, Cholachat Rujikiatkamjorn
Buddhima Indraratna
Geogrids are commonly used in railway construction for reinforcement and stabilisation. When railway ballast becomes fouled due to ballast breakage, infiltration of coal fines, dust and subgrade soil pumping, the reinforcement effect of geogrids decreases significantly. This paper presents results obtained from Discrete Element Method (DEM) to study the interface behaviour of coal-fouled ballast reinforced by geogrid subjected to direct shear testing. In this study, irregularly-shaped aggregates (ballast) were modelled by clumping together 10-20 spheres in appropriate sizes and positions. The geogrid was modelled by bonding a large number of small spheres together to form the desired grid geometry and …
Stabilising Railway Embankments With Geosynthetic Grids And Drains And A Class A Prediction Of Track Behaviour, Buddhima Indraratna, Sanjay Nimbalkar, Cholachat Rujikiatkamjorn
Stabilising Railway Embankments With Geosynthetic Grids And Drains And A Class A Prediction Of Track Behaviour, Buddhima Indraratna, Sanjay Nimbalkar, Cholachat Rujikiatkamjorn
Buddhima Indraratna
The ballast layer is intended to provide a free draining base and sufficient bearing capacity to maintain a proper track alignment. Due to the growth in commuter and industrial traffic, the railway industry needs to fulfil the demands for faster, heavier, and longer trains. However, these high traffic loads often result in a large plastic deformations and degradation of ballast, which in turn, leads to a significant loss of track stability and high maintenance costs. The deformation and degradation of ballast are influenced by factors such as the amplitude and frequency of loading, the number of load cycles, track confining …
Cyclic Behaviour Of Soft Soil Subgrade Improved By Prefabricated Vertical Drains, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Jing Ni
Cyclic Behaviour Of Soft Soil Subgrade Improved By Prefabricated Vertical Drains, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Jing Ni
Buddhima Indraratna
The behaviour of saturated soft clays subjected to cyclic loading is of considerable importance in the design of railway subgrades. Soft clays can be extensively found in many coastal regions of Australia up to significant depths, including the coastal belt and the central part of NSW. These soft clay deposits are characterised by very low bearing capacity and excessive settlement. The increase in generated excess pore pressures due to heavy freight trains significantly reduces the bearing capacity and causes serious damage to the rail infrastructure such as clay pumping underneath railway tracks and excessive subsidence. The use of prefabricated vertical …
Effects Of Fouling On The Stress-Strain-Degradation Behaviour Of Rail Ballast, Buddhima Indraratna, Nayoma C. Tennakoon, Sanjay Nimbalkar, Cholachat Rujikiatkamjorn
Effects Of Fouling On The Stress-Strain-Degradation Behaviour Of Rail Ballast, Buddhima Indraratna, Nayoma C. Tennakoon, Sanjay Nimbalkar, Cholachat Rujikiatkamjorn
Buddhima Indraratna
Ballast is most commonly used as a structural component of rail track due to its high load bearing capacity, resiliency and rapid drainage. However, ballast along coal freight corridors often becomes fouled due to spilling of coal from moving wagons, in addition to further track deterioration attributed to particle breakage and pumping of soft subgrade. Highly fouled ballast needs to be cleaned or replaced to maintain the desired track resiliency, load bearing capacity and the track alignment. In order to identify the risk associated with fouling, it is important to accurately assess the amount of fouling. In this paper, the …
Shear Behaviour Of Rock Joints With Unsaturated Infill, B Indraratna, Wuditha N. Premadasa, E. T. Brown
Shear Behaviour Of Rock Joints With Unsaturated Infill, B Indraratna, Wuditha N. Premadasa, E. T. Brown
Buddhima Indraratna
Behaviour of soil-infilled rock joints has significant importance with respect to the strength of fractured rock mass. The presence of even a small amount of fine-grained infill material within a joint can reduce its shear strength considerably, depending on the degree of saturation of infill. Therefore, it is crucial to examine how the infill material can adversely affect the joint shear strength. Previous studies of infilled joints have mainly been focused on idealised regular joint patterns owing to the simplicity and reproducibility in laboratory testing. Current literature on infilled rock joints has also neglected the effect of the degree of …
Predicted And Observed Behaviour Of Soft Clay Foundations Stabilised With Vertical Drains, Buddhima Indraratna, Wadud Salim, I W Redana
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 …
Experimental Investigations Into Subballast Filtrations Behaviour Under Cyclic Conditions, Laricar Dominic Ortega Trani, Buddhima Indraratna
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 …
The Behaviour Of Ballasted Track Foundations: Track Drainage And Geosynthetic Reinforcement, Buddhima Indraratna, Sanjay Nimbalkar, Nayoma Chulani Tennakoon
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 …
Dem Simulation Of Effect Of Confining Pressure On Ballast Behaviour, P K. Thakur, Buddhima Indraratna, Jayan Sylaja J S Vinod
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 …
Modeling Of Bolted Joint Behaviour Under Constant Normal Stiffness Conditions - Laboratory Study, Buddhima Indraratna, Najdat I. Aziz, A Dey
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 …
Numerical Prediction Of Vadose Zone Behaviour Influenced By Vegetation, Buddhima Indraratna, Behzad Fatahi, Mohammad Hadi Khabbaz
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. …
Experimental And Numerical Modeling Of Shear Behaviour Of Rock Joints, Buddhima Indraratna, A Haque
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 …
Internal Erosional Behaviour Of Lignosulfonate Treated Dispersive Clay, J S. Vinod, Buddhima Indraratna, M A. A Mahamud
Internal Erosional Behaviour Of Lignosulfonate Treated Dispersive Clay, J S. Vinod, Buddhima Indraratna, M A. A Mahamud
Buddhima Indraratna
Internal erosional behaviour of lignosulfonate treated dispersive clay has been studied using the Process Simulation Apparatus for Internal Crack Erosion (PSAICE) designed and built at UOW. Effectiveness of lignosulfonate treated dispersive clay on the erosion resistance has been investigated and its advantage over traditional admixtures is presented. Test results show that the hydraulic shear stress increases with increase in the amount of lignosulfonate. In addition, the micro-chemical analysis has been carried out using FTIR. Based on the Fourier Transform Infrared (FTIR) Spectroscopy results a stabilization mechanism has been proposed for lignosulfonate treated dispersive soil.