C. T. Gnanendran

• Doctor of Philosophy
• Senior Lecturer at UNSW Sydney

This paper investigates the effects of degrees of compaction (initial dry unit weights), recirculation liquid and rate, and environmental temperature on the long-term physical, geotechnical, and biochemical properties of municipal solid wastes (MSWs) biodegraded for approximately 800 days. Four field bioreactors were filled with fresh MSWs collecte...

This paper investigates the geotechnical properties of a type of synthetic municipal solid waste (MSW). The tests were conducted on five groups of synthetic MSW compositions, based on the field characterization of fresh MSW samples collected from Mugga Lane landfill site, ACT, Australia. Compaction, hydraulic conductivity, compression, drained and...

Intermediate soil cover has been commonly used in Australian landfills. To estimate the liquid flow through the landfill waste body, it is important to understand the hydraulic properties of those organic cover soils, especially with exposure to landfill leachate contamination. A laboratory testing program has been set to investigate the hydraulic...

The Nerang Broadbeach Roadway (NBR) embankment in Australia is founded on soft clay deposits. The embankment sections were preloaded and surcharged-preloaded to limit the post-construction deformation and to avoid stability failure. In this paper, we discuss the NBR embankment’s geology, geotechnical properties of the subsurface, and long-term fiel...

We develop a non-associated flow rule (NAFR) based elasto-viscoplastic (EVP) model for isotropic clays. For the model formulation, we introduce the critical state soil mechanics theory (CSSMT), the bounding surface theory and Perzyna's overstress theory. The NAFR based EVP model comprises three surfaces: the potential surface, the reference surface...

We develop a non-associated flow rule (NAFR)-based elasto-viscoplastic (EVP) model for isotropic clays. For the model formulation, we introduce the critical state soil mechanics theory (CSSMT), the bounding surface theory and Perzyna’s overstress theory. The NAFR based EVP model comprises three surfaces: the potential surface, the reference surface...

In this paper, we develop an elasto-viscoplastic (EVP) model for clay using the non-associated flow rule. This is accomplished by using a modified form of the Perzyna's overstressed EVP theory, the critical state soil mechanics, and the multi-surface theory. The new model includes six parameters, five of which are identical to those in the critical...

Investigation into time dependent long-term performance of Prefabricated Vertical Drains (PVDs) combined with vacuum consolidation in thick deposits of clay has been extremely limited. Predicting both settlements and excess pore pressures in such cases has become increasingly challenging when time duration is long-term, e.g. several years. In discu...

In this paper, we develop an elasto-viscoplastic (EVP) model for clay using the non-associated flow rule. This is accomplished by using a modified form of the Perzyna's overstressed EVP theory, the critical state soil mechanics, and the multi-surface theory. The new model includes six parameters, five of which are identical to those in the critical...

This paper investigates the cyclic loading responses of a strip footing supported by a geosynthetic reinforced fill embankment. A series of large-scale model footing tests were conducted first to investigate the accumulation of permanent footing displacement and residual vertical soil stress over large number of load cycles. The embankment fill was...

Settlement in municipal solid waste (MSW) in landfills and its change with time is a complex process, because of the break-down potential of solids, heterogeneity of the material, variable particle size, and decomposition processes of organics induced by biodegradation. Waste properties, composition, distribution, and load applied vary significantl...

Prefabricated vertical drains (PVDs) with vacuum suction have helped to shorten the consolidation time significantly in ground improvement projects. This method is claimed to be more effective and economical in consolidating deep soft clay layers. However, recent research has shown that the vacuum suction applied to PVD near the ground surface may...

This paper presents an elastic-viscoplastic (EVP) constitutive model in triaxial space and general stress space for isotropic clays. The EVP model is anchored in the bounding surface theory along with the mapping rule and adopts a critical state soil mechanics framework. It incorporates creep effects, and a non-linear creep function is used in the...

This paper presents an elastic-viscoplastic (EVP) constitutive model in triaxial space and general stress space for isotropic clays. The EVP model is anchored in bounding surface theory along with the mapping rule and adopts a critical-state soil mechanics framework. It incorporates creep effects, and a nonlinear creep function is used in the model...

Consideration of vacuum consolidation in soft clays with respect to its long-term performance has been extremely limited, especially concerning thick clay deposits having significant creep characteristics. Popular coupled-consolidation elasto-plastic analysis models such as Cam-Clay cannot be used to predict long-term time-dependent deformational b...

This paper presents an elastic-viscoplastic (EVP) constitutive model in triaxial space and general stress space for isotropic clays. The EVP model is anchored in bounding surface theory along with the mapping rule and adopts a critical-state soil mechanics framework. It incorporates creep effects, and a nonlinear creep function is used in the model...

This paper investigates the settlement behaviour of a strip footing seating on the crest of an embankment and subjected to cyclic loading. The embankment fill is a dense sand and the issue is the gradual accumulation of settlement over a large number of load repetitions. Cyclic triaxial tests were first conducted to develop a consistent but simple...

The fatigue characteristic of a lightly stabilized granular material under traffic loading is an important consideration for the design of a pavement containing such material. This paper presents the evaluation of fatigue behavior of lightly stabilised granular materials using flexural and indirect diametral tensile (IDT) testing. The experimental...

Lightly cementitiously stabilized granular materials are generally characterised by their tensile properties that are required for the analysis and design of a pavement structure involving these materials. Tensile properties include tensile strength, stiffness modulus, and Poisson's ratio. However, there are limited studies on the mechanistic deter...

The fatigue characteristics of a lightly stabilized granular material under traffic loading are important considerations for the design of a pavement containing such material. This paper examines the use of flexural testing with on-sample midspan deflection measurement for determining fatigue characteristics of lightly stabilized granular base mate...

The behaviors of Hall’s Creek test embankment constructed on an alluvium deposit in Moncton, New Brunswick, and the reinforced test embankment constructed on a soft compressible soil in Sackville, New Brunswick, where a high-strength polyester woven geotextile was used as basal reinforcement are discussed in this chapter. The soils at both these si...

Lightly stabilized granular materials with slow-setting cementitious binders are widely used in the construction of new pavements and rehabilitation of old pavements in Australia and other countries. Higher strength and durability of these materials combined with relatively low cost are reasons they are widely used. The mechanistic-empirical design...

This paper investigates the damage characteristics of a lightly stabilized granular material using cyclic load flexural testing with an improved deflection measurement setup. Beam specimens were prepared from atypical granular base material lightly stabilised with 1.5 % cement-flyash, cured for 28 days and tested at different stress ratios (SRs) un...

In this chapter, interpretation of the properties of the Nerang-Broadbeach Road (NBR) embankment's foundation of soft sensitive estuarine clay deposit from laboratory as well as field tests and the performance prediction of the embankment in comparison with field monitoring data are presented. To enhance the foundation's load-bearing capacity and a...

Lightly cementitiously stabilized granular materials are generally characterized by their tensile properties and this paper examines the use of monotonic and cyclic load flexural testing to determine the tensile characteristics of these materials. The research reported in this paper included the determination of modulus of rupture as well as static...

This study presents the outcome of an experimental investigation focused on lightly stabilised material's durability under freeze-thaw (f-t) and wet-dry (w-d) conditions. A widely used road base granular base material was selected for the study which was then reconstituted to a particular particle size distribution. A combination of cement and flya...

In this paper a non-associated flow rule based elasto-viscoplastic (EVP) constitutive model is proposed for soft clays. The model is based on the critical state concepts along with viscoplasticity and adopting bounding surface approach. To predict the behavior of the clay, a total of three surfaces (potential surface, reference surface and loading...

The stress-strain responses from laboratory triaxial tests of dense sandy soil show post-peak, strain-softening behavior. The Mohr-Coulomb failure criterion - commonly used in the numerical analyses to model sandy soil - is based on constant values of friction angle, dilation angle and cohesion. However, such assumptions cannot provide post-peak, s...

This paper presents the results from an experimental study of the flexural behavior of a lightly stabilized granular material subjected to different freeze-thaw (f-t) cycles. A granular base material with a reconstituted particle size distribution, stabilized using cement-flyash in a ratio of 3:1 with two different binder contents of 1.5% and 3%, w...

The performance of a foundation on a sloped granular fill can be improved by using different types of reinforcing elements below it. In this experimental study, the effects of short vertical reinforcing bars within the body of a sloped fill on the strength and deformational behavior of a strip foundation over it will be investigated under repeated...

An investigation into the time-dependent deformational behavior of the unreinforced section of the Coombabah Creek trial embankment constructed near the Gold Coast highway, Queensland, Australia, on sensitive soft clay is discussed in this paper. This embankment was instrumented to monitor the settlement near the centerline, and excess pore pressur...

Different classes of constitutive models have been proposed to capture the time-dependent behaviour of soft soil (creep, stress relaxation, rate dependency). This paper critically reviews many of the models developed based on understanding of the time dependent stress-strain-stress rate-strain rate behaviour of soils and viscoplasticity in terms of...

Behaviour of two embedded piles subjected to passive loading due to construction of an embankment was modelled in this paper. The piles were installed at the berm section of an embankment in a later stage of its construction. The investigation was carried out using a combination of two- and three-dimensional analyses. The analysis results were comp...

A finite element (FE) formulation for electro-osmotic consolidation (EOC) analysis is developed in this paper which was implemented in a FE analysis (FEA) program. This formulation is integrated with the elastoplastic Modified Cam Clay (MCC) model to capture the nonlinear stress–strain behaviour of the soil during EOC using the fully coupled analys...

The results from an investigation into the long-term performance of the preloaded Nerang-Broadbeach Roadway (NBR) embankment near the Gold Coast in Queensland, Australia, are presented in this paper. The soil profile along this roadway consists of deep Cainozoic estuarine alluvial soft clay deposit. To predict the performance of the preloaded emban...

Resilient moduli of pavement layers are the basic input parameters for the design of pavements with multiple layers in the current mechanistic empirical pavement design guides. Field measurements are generally believed to provide accurate values to back-calculate pavement layer moduli, but the tests to measure the relevant parameters are expensive,...

This paper examines the non-linear stress–strain behaviour of lightly stabilised granular materials and stiffness modulus from unconfined compression testing and their predictability based on modified and extended Ramberg–Osgood expression. Unconfined compressive strength (UCS) testing with the internal deformation measurement setup was carried out...

Foundations are sometimes placed very close to each other because of space limitations or to limit the footing loads or to accommodate certain structural details. When footings are placed at close spacing, they interact with each other and the behaviour of each individual footing is altered compared to that of a single isolated footing. Also, found...

This paper presents an alternative criterion (simplified method) to determine the cohesion (c) and internal angle of friction (φ) properties for two granular materials lightly stabilized with slag lime and general blend (GB) cement–fly ash using indirect diametral tensile (IDT) strength and unconfined compressive strength (UCS). The c and φ values...

It has long been recognised that cyclic live loads on foundations greatly affect the strength and deformational characteristics of the foundation soil due to repeated application of stress. However, the effects of cyclic loading on foundations located near the crest of a slope have not been investigated adequately. Therefore, the effects of cyclic...

A laboratory study was undertaken to evaluate the effect of ageing on the indirect tensile characteristics of a typical granular base material lightly stabilized with cement-flyash. Cylindrical samples were prepared using a gyratory compactor and cured for various curing periods in a moist room maintained at constant temperature and controlled humi...

This paper presents a new and improved flexural beam testing setup for characterization of granular base materials lightly stabilized with cement-flyash binder for pavement design. All the samples were prepared at their optimum moisture contents (OMCs), cured for 28 days and then tested under cyclic loading conditions at different stress levels. Th...

This paper presents an alternative criterion (simplified method) to determine the cohesion (c) and internal angle of friction (phi) properties for two granular materials lightly stabilized with slag lime and general blend (GB) cement-fly ash using indirect diametral tensile (IDT) strength and unconfined compressive strength (UCS). The c and phi val...

This paper examines the nonlinear stress-strain behavior of lightly stabilized granular base materials and presents a method to predict them based on modified and extended Ramberg-Osgood expression from unconfined compression (UC) testing. A typical granular material was lightly stabilized with 0.5–3.0% cement-flyash (CF) as well as with 1.5–3.0% s...

The underlying mechanism of static and cyclic liquefaction of loose contractant sandy soil is unstable behaviour associated with deviatoric strain-softening. Such unstable (strain-softening) behaviour has been referred to as static or cyclic instability depending on whether the loading condition is monotonic or cyclic. Past research into linkage be...

Stress history is recognised to play a major role in determining stress–strain behaviour of soil in undrained shearing. Most experimental studies on the effects of stress history on undrained behaviour are mainly limited to clean sand. In this paper, an experimental study carried out to investigate the effect of stress history on the undrained beha...

Physical modelling is often used to investigate geotechnical problems where prototype investigations are rather difficult, uneconomical and time-consuming. However, the establishment of a small-scale physical model test (SSPMT) facility in which complex loading (e.g. different types of cyclic loading) needs to be applied could involve high cost and...

This paper presents the results from an experimental study on the characterisation of lightly stabilised granular base materials by monotonic load/displacement flexural beam testing which was carried out on two granular base materials lightly stabilised with 1% to 3% cement—fly ash. Effects of the loading/displacement rate on the flexural propertie...

Laboratory model tests in geotechnical engineering are routinely performed in small concrete or steel test tanks to examine the bearing capacity of footings, lateral earth pressures on retaining walls, behavior of reinforced foundation soils, and more. Results from these model tests are influenced by the shear forces generated on the sidewalls. The...

Geo-synthetic reinforcements are often used to enhance the stability of geotechnical structures such as embankments. These geosynthetic polymers often show significant creep deformational behaviour. In the short-term performance of a geotechnical structure, it may not play a significant role. However, while dealing with the long term behaviour, it...

In this paper, laboratory model tests for determining the changes in ultimate bearing capacity and permanent deformation behaviour of a strip footing near the crest of a slope at varying slope angles due to cyclic loading are presented. The change in bearing capacity due to cyclic loading was determined by first performing a monotonic load test on...

A bikeway underpass culvert had to be constructed at the edge of Nerang- Broadbeach Road, Gold Coast, Queensland, Australia. This was achieved by modifying the side slope of the existing road embankment, which was founded on a soft compressible soil deposit, incorporating reinforced soil system (RSS) steep walls. Site investigation involved field t...

The application of electro-osmosis (EO) for stabilizing soft clays is receiving more attention in geotechnical engineering. When the application of traditional ground improvement techniques, such as surcharge, pre-loading, wick drains, and vacuum pre-loading, is not appropriate for a particular situation, innovative techniques such as electro-osmos...

An experimental study has been undertaken to investigate the effect of loading rate on the flexural properties of lightly stabilized granular materials. The flexural beam samples were prepared from a typical granular material stabilized lightly with 1.5% cement-flyash and moisture at optimum moisture content. Then the samples were cured for 7 days...

This paper presents the finite element (FE) analysis of the consolidation of the foundation of an embankment constructed over soft clay deposit which shows significant time dependent behaviour and was improved with prefabricated vertical drains. To assess the capability of a simple elastic viscoplastic (EVP) model to predict the long term performan...

This paper examines the pavement model test box (PMTB) testing method and its suitability for determining the stiffness modulus, fatigue and permanent deformation properties of a pavement structure constructed with a cementitiously stabilized granular base layer of 250 mm thickness and a clay subgrade layer of 330 mm thickness that are required for...

This paper examines the pavement model test box (PMTB) testing method and its suitability for determining the stiffness modulus, fatigue and permanent deformation properties of a pavement structure constructed with a cementitiously stabilized granular base layer of 250 mm thickness and a clay subgrade layer of 330 mm thickness that are required for...

This paper presents the analysis of nonlinear stress-strain behavior of lightly stabilized granular base materials from unconfi ned compressive strength (UCS) testing. The samples, prepared at its opti-mum moisture content, were cured for 28 days and then tested in the universal testing machine to obtain the stress-strain relationship. However, an...

The consolidation of the soft foundation soil of a geogrid-reinforced embankment, improved with prefabricated vertical drains (PVDs), is modelled in this paper using two-dimensional (2D) plane strain coupled finite element (FE) analysis to predict long-term multiple behaviour characteristics (e.g., settlement, lateral displacement, excess pore-wate...

A new resurfacing method has been proposed recently for rehabilitating low-cost unpaved resource access (forest) roads using a mobile crusher. The quality and performance of the road rehabilitated using this new method have been a concern for some forestry companies and a study was initiated to compare it with the traditional resurfacing method whe...

The predictability of the behaviour of an embankment constructed on a soft soil with three types of fully coupled finite element analysis models; namely a rate-formulated elasto-viscoplastic, a creep-formulated elasto-viscoplastic, and modified Cam clay (MCC) elastoplastic material model for the foundation soil is examined in this paper. The well d...

The finite element analysis of an instrumented geotextile-reinforced test embankment is described and the results are compared with the field measurements. The embankment was constructed to failure on a soft compressible organic clayey silt deposit at Sackville, New Brunswick. The analysis adopts a fully coupled large-strain elasto-plastic Biot con...

For the construction of a shallow foundation two important issues that we need to consider are soil type on which it will rest and the possibility of any neighbouring footing constructed very close to it. In most of the cases, shallow foundations are constructed very close to each other on a layered soil stratum and the bearing capacity of each ind...

Aspects of using slag, an industrial waste by-product, for stabilizing road base materials are examined. Indirect diametrical tensile (IDT) testing was carried out to determine the strength and stiffness characteristics of base materials stabilized lightly with slag-lime. The samples, prepared at its optimum moisture content using gyratory compacti...

Numerical analysis of indirect diametrical tensile (IDT) testing, using experimental load-deformation data, could provide a simple and fast method to characterize the lightly stabilized granular materials (LSGM). Through the development of appropriate computer algorithms and the use of high speed computers, the stiffness and strength properties wer...

Use of an accelerated pavement testing (APT) facility has become one of the most popular methods around the world for testing the performance of various types of pavement materials and for determining their characteristics. In the current study using an APT facility, the model pavement structure was simulated in a steel tank of dimension 1.1 m x 1....

Stabilization of granular materials with low percentage of slow setting binders, such as slag lime, for constructing new pavements and/or rehabilitation of existing granular pavements has economical and environmental benefits. The fatigue life of a lightly stabilized granular material under traffic type repeated or cyclic loading is an important co...

A cyclic load pavement model testing facility was developed for studying the fatigue and permanent deformation characteristics of different materials in a pavement structure. In particular, a typical pavement structure consisting of a lightly stabilised granular road base material, commonly referred to as modified material, over a soft clay subgrad...

Cementitious binders are commonly used to improve the engineering properties of granular materials for improving their performance in new pavements as well as in rehabilitating old pavements in Australia and other countries. These stabilized materials are usually characterized with their stiffness modulus and tensile strength for pavement design. T...

This paper presents the findings of a laboratory investigation on the characterization of a freshly quarried granular base material lightly stabilized with slag-lime cementitious binder involving unconfined compression (UC) testing and indirect diametrical tensile (IDT) testing, both with internal displacement measurements. The UC test investigatio...

This paper presents modelling of the consolidation of foundation soil under a wide embankment constructed over soft soil. An elasticviscoplastic (EVP) constitutive model is used to represent the foundation soil for the coupled finite element analysis (FEA). A unit-cell analysis is carried out to capture the maximum settlement and the development of...

Soft soils are problematic due to their low shear strength, high water content and large time dependent deformations. Elastoplastic models like Modified Cam clay (MCC) are often deficient in describing such behaviour as they do not include the viscous (or time dependent) behaviour of soil in their mathematical formulation. A new Elasto-viscoplastic...

This paper presents the determination of stiffness modulus of a freshly quarried granular material stabilized lightly with cement and fly-ash from indirect diametrical tensile (IDT) and accelerated pavement testing (APT). Internal displacement measurement setup was used in the IDT testing to calculate the IDT strength and stiffness modulus. Whereas...

An experimental study was carried out to investigate the static liquefaction behaviour of sand with a small amount of plastic and nonplastic fines. Five series of tests were conducted in drained and undrained conditions. The drained test results indicate not only that the failure line coincides with the critical state, but also that the development...

This paper examines the indirect diametrical tensile (IDT) testing method and its suitability for determining the tensile strength and stiffness modulus properties of a lightly cementitiously stabilized granular base material that are required for the design of a pavement structure involving this material. A new IDT testing setup with internal defo...

Lightly stabilised granular materials with cementitious binders are generally characterised by their stiffness modulus and this paper examines the use of monotonic and cyclic load indirect diametrical tensile (IDT) testing to determine the stiffness characteristics of these materials. The experimental programme included the determination of density...

This paper examines the characterization of a granular material lightly stabilized with slag-lime cementitious binder particularly utilizing the monotonic and cyclic load IDT testing method. An extensive laboratory investigation was carried out to determine the mechanical properties of the lightly stabilized granular material and to establish fatig...

Void ratio has traditionally been used as a state variable for predicting the liquefaction behaviour of soils under the critical state soil mechanics framework. Recent publications show that void ratio may not be a good state variable for characterizing sand with fines. An alternative state variable referred to as the equivalent granular void ratio...

This paper presents the long-term performance of a wide geogrid-reinforced road embankment constructed on soft clay improved with prefabricated vertical drains (PVDs) at a freeway extension site 150km north of Sydney in Australia. The foundation soil and the embankment were instrumented and monitored for about 400days for excess pore-water pressure...

Performance of foundations near sloped fills is an important consideration for the design of bridge abutments. Inclusion of geosynthetic reinforcement within the fill is advocated to be beneficial for improving the stability of the slope and the bearing capacity of the bridge abutment foundation located near the sloped fill. The aim of this numeric...

A new elastic-viscoplastic model is proposed in this paper to describe the rate sensitive behaviour of soft clay soils. The model is based on Bjerrum's (1967) concept of delayed compression and Perzyna's (1963, 1966) formulation of visco-plasticity and adopting Modified Cam-Clay (Roscoe and Burland, 1968) framework. The proposed model is similar to...

Model tests were carried out in a 1.1 m x 1 m x 0.6 m steel tank with a compacted sandy material as the foundation soil. The load-deformation behaviour of a 0.09 m x 0.09 m square model footing under concurrent vertical and horizontal cyclic loading was investigated. Details of the experimental setup, instrumentation and data acquisition/control sy...

The behaviours of Hall's Creek test embankment constructed on an alluvium deposit in Moncton, New Brunswick, and the reinforced test embankment constructed on a soft compressible soil in Sackville, New Brunswick, where a high-strength polyester woven geotextile was used as basal reinforcement are discussed in this chapter. The soils at both these s...

Cementitious stabilisation of pavement materials has a long history of use in Australia and other countries. Since its first recorded attempts in the 1940s, stabilisation has been further developed and now a wide range of binder options exist. The Australian Accelerated Load Facility (ALF) program has allowed advancement of stabilisation material a...

Australian practice is moving towards the utilisation of gyratory compacted samples tested by indirect diametrical tensile testing for determination of both modulus and fatigue life of cementitiously stabilised pavement materials. At the same time, conformance testing is expected to remain an unconfined compressive strength and density based assess...

Insitu stabilisation of pavement materials with cementitious binders is a well recognised method of rehabilitating pavements for local roads and highways. Since its introduction in Australia in the 1950s, this technology has seen a broadening of the materials available for use as binders, the introduction of machinery capable of more accurately spr...

Insitu stabilisation of pavement materials with cementitious binders is a well recognised method of rehabilitating pavements for local roads and highways. Since its introduction in Australia in the 1950s, this technology has seen a broadening of the materials available for use as binders, the introduction of machinery capable of more accurately spr...

The instrumentation, construction, and field performance of a full-scale test embankment constructed on a soft compressible organic clayey silt is described. The construction sequence, the observed vertical and horizontal dis - placements, and the pore pressure response are presented. The embankment behaved elastically up to a thickness of about 3....

The stabilising force provided by a layer of geogrid reinforcement embedded in the body of a sloped fill subjected to loading from a footing located near the crest was investigated through a laboratory model study and the results are reported in this paper. This study indicates that the geogrid reinforcement could be instrumented more reliably with...

The instrumentation, construction, and field performance of a full-scale test embankment constructed on a soft compressible organic clayey silt is described. The construction sequence, the observed vertical and horizontal displacements, and the pore pressure response are presented. The embankment behaved elastically up to a thickness of about 3.65...

Firstly the authors would like to thank Gnanendran et al. and Bergado for their interest on the work and for their contributions. These contributions improve the work in the sense that they provide additional information or knowledge that were unavailable to the authors at the time of preparation of the paper. In their discussion Gnanendran et al....

The development and propagation of cracks in relation to the construction sequence and the manner in which the embankment failed are described. The field data suggest that the shear strength of the foundation soil was mobilized at a fill thickness between 5 and 5.7m. However, due to the stabilizing effect of the geotextile reinforcmenet, the embank...