Engineering Commons^™

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 …

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 …

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 …

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 …

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 …

Performance Of A Prb For The Remediation Of Acidic Groundwater In Acid Sulfate Soil Terrain, Buddhima Indraratna, Gyanendra Regmi, Long Nghiem, A. Golab

Buddhima Indraratna

Contaminated groundwater resulting from pyrite oxidation of acid sulfate soils (ASSs) is a major environmental problem in coastal Australia. A column test was carried out for an extended period with recycled concrete to study the efficiency of the reactive materials for neutralizing acidic groundwater. Results show that the actual acid neutralization capacity of the recycled concrete could decrease to less than 50% of the theoretical value due to armoring effects. Nevertheless, the performance is good as a spot treatment in ASS Terrain using a near-zero cost waste product. Based on the test results and site characterization, a permeable reactive barrier …

Use Of Geosynthetics In Railways Including Geocomposites And Vertical Drains, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Sanjay Nimbalkar

Buddhima Indraratna

Australia relies heavily on rail for the transportation of bulk commodities and passenger services, and has introduced faster and heavier trains in recent years due to a growing demand. 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 track maintenance works. A proper understanding of load transfer mechanisms and their effects on track deformations are essential prerequisites for minimising maintenance costs. The reinforcement of the track by …

Effective Remediation Of Groundwater In Acid Sulphate Soil Terrain, Gyanendra Regmi, Buddhima Indraratna, Long Nghiem

Buddhima Indraratna

Acidic groundwater, generated from acid sulphate soil (ASS) is a major geo-environmental problem in Australia. Manipulation of groundwater through the use of weirs and gates in the nearby creeks and drains of ASS, which is being practised right now for preventing pyrite oxidation, are not effective in low land floodplains due to the risk of flooding. The application of permeable reactive barrier (PRB) can be a novel alternative for remediation of acidic groundwater in such floodplains. Laboratory column experiments were carried out prior to installation of the PRB for examining the efficiency of the material. Results of these experiments have …

Stabilization Of An Erodible Soil Using A Chemical Admixtures, Buddhima Indraratna, M.A.A Mahamud, J S. Vinod, Vasantha Wijeyakulasuriya

Buddhima Indraratna

This paper presents internal erosion behaviour of an erodible soil stabilized by chemical admixtures using a novel Process Simulation Apparatus for Internal Crack Erosion (PSAICE), designed and built at University of Wollongong. Laboratory tests were carried out on typical erodible soils (collected from Wombeyan caves, Australia) stabilised using chemical admixtures such as lignosulfonate and cement. Test results reveal that the erosion parameters such as critical shear stress and coefficient of soil erosion were improved with the increase in the amount of chemicals. It has been seen that lignosulfonate exhibits better performance in stabilizing the erodible soil compared to cement. Based …

Ground Improvement/Grouting/Dredging, Buddhima Indraratna

Buddhima Indraratna

Due to the rapid increase in population, industrial and construction boom especially in the urban as well as coastal regions of many countries have considerably intensified the inevitable need for infrastructure development on problematic soils including soft compressible clays, deposits with low bearing capacities, soils prone to erosion and collapse upon wetting, highly fractured and jointed rock mass among other geological deposits. Good quality geologic materials for construction are also becoming scarce, exacerbated by numerous environmental constraints in various countries. Due to these reasons and environmental restrictions on certain public works, ground improvement has now become an integrated and essential …

Deformation And Degradation Mechanics Of Recycled Ballast Stabilised With Geosynthetics, Buddhima Indraratna, Wadud Salim

Buddhima Indraratna

Railway ballast deforms and degrades progressively under heavy train (cyclic) loading. Ballast degradation is influenced by several factors including the amplitude and number of load cycles, density of aggregates, track confining pressure, angularity, and most importantly, the fracture strength of individual grains. The degraded ballast is usually cleaned on track, otherwise fully or partially replaced by fresh ballast, depending on the track settlement and current density. The disposed waste ballast may be cleaned, sieved and re-used in the track. However, due to the breakage of the sharp edges and the development of micro-cracks during the previous loading cycles, recycled ballast …

Investigation On Effectiveness Of A Prefabricated Vertical Drain During Cyclic Loading, Buddhima Indraratna, Jing Ni, Cholachat Rujikiatkamjorn

Buddhima Indraratna

The effectiveness of prefabricated vertical drains (PVDs) in enhancing the stability of soft soils during cyclic loading was investigated using triaxial cyclic loading tests. Both undrained and with PVD tests were employed to study the associated excess pore pressure and accumulated strain under the repeated loading condition. The loading frequency and cyclic stress ratio have been chosen to be the variables which influence the performance of soft clays. The experimental results illustrate that with PVDs, the excess pore water pressure generation during cyclic loading decreases significantly. It is found that the excess pore water pressure build up depends on both …

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.

A Multi-Staged Management Strategy For Restoring Tidal Flushing, William Glamore, Buddhima Indraratna

Buddhima Indraratna

Tidal restoration/wetland rehabilitation projects are being undertallimitations, this paper presents a tidal restoration/floodgate manipulation strategy that was developed from a four-year field study undertaken in southeastern NSW and subsequently applied at multiple field sites. An eight stage methodology is proposed to incorporate water quality, hydraulics, groundwater/saline intrusion, hydrology, field monitoring and flood design criteria. The strategy begins with a quantification of perceived outcomes for the study. Using these goals, the potential improvement in water quality are calculated using ion association models and field sampling techniques. The third stage quantifies the spatial flooding extent using GIS spatial analysis methods. The risks …

Finite Element Simulation Of Mandrel Penetration In A Normally Consolidated Soil, Cholachat Rujikiatkamjorn, Ali Ghandeharioon, Buddhima Indraratna

Buddhima Indraratna

In this paper, a finite element simulation of the mandrel penetration in normally consolidated soils is presented using a commercial finite element code (ABAQUS). A coupled analysis with large-strain frictional contact is used to simulate the soil-mandrel interface during mandrel penetration. The modified Cam clay model is used to represent the soft soil. The numerical predictions are then compared with the results obtained from the large scale laboratory tests to predict the extent of the smear zone. A large scale consolidation test was conducted with the rate-controlled device used to install the mandrel. The associated excess pore pressures at various …

The Impact Of Floodgate Modifications On Water Quality In Acid Sulphate Soil Terrains, William Glamore, Buddhima Indraratna

Buddhima Indraratna

The installation of one-way tidal restricting floodgates in regions containing acid sulphate soils has increased the problems associated with acid drainage in many areas of coastal Australia. In southeastern NSW, one-way flap gates installed in deep flood mitigation drains maintain a low groundwater table and increase acid production and transport. Moreover, by restricting the intrusion of brackish water into the drainage system, the floodgates create a reservoir of acidic water. Recent studies suggest that by allowing a controlled amount of brackish water into the drains, via modified floodgates, buffering agents can neutralize the acidic water. A fifteen-month study was undertaken …

Use Of Geosynthetics For Stabilizing Recycled Ballast In Railway Track Substructures, Buddhima Indraratna, Mohamed A. Shahin, Wadud Salim

Buddhima Indraratna

Traditional ballasted railway track substructure usually consists of graded layers of granular media of ballast and subballast (capping) placed above a compacted subgrade (formation soil). Ballast particles breakdown and deteriorate progressively under heavy train cyclic loading. Breakage of ballast is always associated with railway track deformation, which requires costly regular track maintenance in the form of replacing the degraded (recycled) ballast with fresh aggregates and subsequent re-compaction (tamping). In this paper, the use of geosynthetics for improving the deformation and degradation characteristics of recycled ballast is investigated. The prospective use of three different types of geosynthetics (i.e. geogrid, geotextile, and …

Creativity And Innovation: A Comparative Analysis Of Assessment Measures For The Domains Of Technology, Engineering, And Business, Tyler Lewis

Theses and Dissertations

The purpose of this literature review is to investigate and discuss: (1) the characteristics measured by innovation assessments, and (2) the comparison of characteristics measured by creativity assessments with those of innovation assessments. This will be done by: (1) collecting creativity and innovation assessments, and (2) comparing and contrasting the characteristics measured by each assessment. This study reveals that innovation assessments do not measure the innovation process in its entirety. The findings show that creativity and innovation assessments lack in assessing the entire innovation process, assessing the innovation process on an individual level, and assessing an individual's change or growth …

A Novel Device And Nanoparticle-Based Approach For Improving Diagnosis And Treatment Of Pelvic Inflammatory Disease, Natasha Faith Cover

USF Tampa Graduate Theses and Dissertations

Pelvic Inflammatory Disease (PID) is one of the most common causes of morbidity in women. PID is a polymicrobial infection of the female reproductive tract, and is associated with pelvic pain, abnormal uterine bleeding, and tubal damage that can lead to ectopic pregnancies and infertility. It is curable but the effects of PID can be permanent if not properly diagnosed and treated. PID presents as a spectrum of disease and is often missed at early stages; even acute PID can be difficult to diagnose, as there is no single conclusive diagnostic test. Currently, PID is identified and treated syndromically because …

Damage Tolerance Of Buckling-Critical Unidirectional Carbon, Glass,And Basalt Fiber Composites In Co-Cured Aramid Sleeves, Michael D. Embley

Theses and Dissertations

Compression strength after impact tests were conducted on unidirectional composite rods with sleeves. These elements represent local members of open three-dimensional composite lattice structures (e.g., based on isogrid or IsoTruss® technologies). The unidirectional cores composed of carbon, glass, or basalt fiber/epoxy composites were co-cured in aramid sleeves. Sleeve patterns included both bi-directional (unsymmetric) braids and unidirectional spiral wraps with sleeve coverage ranging from nominally half to full. The diameters were nominally 8 and 11 mm (5/16 and 7/16 in). The larger diameter had nominally twice the cross-sectional area, to quantify the effects of scaling. The specimens were long enough to …

Engineering Of A Knowledge Management System For Relational Medical Diagnosis, Maria Carolina Herrera-Hernandez

USF Tampa Graduate Theses and Dissertations

The increasingly high costs of health care in the U.S. have led the general public to search for different medical approaches. Since the 1990's, the use of Complementary and Alternative Medicine (CAM) has radically increased in the U.S. due to its approach to treat physical, mental, and emotional causes of illness. In 2009, the National Health Statistics reported the impact of CAM in the U.S. health care economy, with population expenditures of $14.8 billion out-of-pocket on natural Medicine and $12.4 billion out-of-pocket on visits to CAM providers as a complement to Western Medicine care.

CAM interconnects human functions to reach …

Damage Tolerance Of Unidirectional Basalt/Epoxy Composites In Co-Cured Aramid Sleeves, Devin Nelson Allen

Theses and Dissertations

Unidirectional basalt fiber rods consolidated with an aramid sleeve were measured for compression strength after impact at various energy levels and compared to undamaged control specimens. These structural elements represent local members of open three-dimensional composite lattice structures (e.g., based on isogrid or IsoTruss® technologies) that are continuously fabricated using advanced three-dimensional braiding techniques. The unidirectional core specimens, nominally 8 mm (5/16") and 11 mm (7/16") in diameter, were manufactured using bi-directional braided sleeves or unidirectional spiral sleeves with full or partial (approximately half) coverage of the core fibers. The 51 mm (2") specimens were shorter than the critical buckling …

Model Decomposition And Constraints To Parametrically Partition Design Space In A Collaborative Cax Environment, Felicia Diane Marshall

Theses and Dissertations

An industry survey was conducted to collect information on current collaboration methods and project management and communication structures. The results, along with other design collaboration philosophies, were used to develop a method of coordinating users in a multi-user design space. These thesis methods will regulate collaboration and avoid user collisions in the same model space, either by cooperative interaction or by spatial decomposition with regional blocking. The method partitions the design space by integrating a graphical user interface tool into the engineering application used to define and assign the necessary tasks of the project. A simple implementation of this method …

Synthesis And Characterization Of One- And Two-Dimensional Novel Nanomaterials, Yu Zhong

Electronic Thesis and Dissertation Repository

Nanomaterials have attracted extensive interest due to their unique structure and excellent properties compared with their bulk counterparts. To obtain nanodevices with controlled properties, it is prerequisite to synthesize nanostructured materials with designed architecture.

In this work, low (one- and two-) dimensional nanomaterials with controlled structures have been synthesized and characterized based on chemical vapour deposition strategy. Our research targets cover one-dimensinoal hollow, solid, and solid @ hollow heterostructural nanomaterials including carbon nanotubes (CNTs), nitrogen-doped carbon nanotubes (NCNTs), SnO₂ nanowires, Mo doped-SnO₂ nanowires, Sn nanowires encapsulated in CNTs (Sn@CNTs), and two-dimensional Mo₂S₃ nanopetals. Dependence of …

Differential Regulation Of Articular Cartilage Tensile Properties By Igf-1 And Tgf-Β1 During In Vitro Growth, M. E. Stender, N. T. Balcom, B. Berg-Johansen, K. J. Dills, D. Dyk, S. J. Hazelwood, A. C. Chen, R. L. Sah, S. M. Klisch

Mechanical Engineering

No abstract provided.

Pso Based Optimal Placement And Setting Of Facts Devicesfor Improving The Performance Of Power Distribution System, Tibin Joseph

Tibin Joseph

No abstract provided.

A Benchmark Study On The Thermal Conductivity Of Nanofluids, Jacopo Buongiorno, David C. Venerus, Naveen Prabhat, Thomas Mckrell, Jessica Townsend, Rebecca J. Christianson, Yuriv V. Tolmachev, Pawel Keblinski, Lin-Wen Hu, Jorge L. Alvarado, In Cheol Bang, Sandra W. Bishnoi, Marco Bonetti, Frank Botz, Anselmo Cecere, Yun Chang, Gang Chen, Haisheng Chen, Sung Jae Chung, Minking K. Chyu, Sarit K. Das, Roberto Di Paola, Yulong Ding, Frank Dubois, Grzegorz Dzido, Jacob Eapen, Werner Escher, Denis Funfschilling, Quentin Galand, Jinwei Gao, Patricia E. Gharagozloo, Kenneth E. Goodson, Jorge Gustavo Gutierrez, Haiping Hong, Mark Horton, Kyo Sik Hwang, Carlo S. Iorio, Seok Pil Jang, Andrzej B. Jarzebski, Yiran Jiang, Stephan Kabelac, Liwen Jin, Aravind Kamath, Mark A. Kedzierski, Lim Geok Kieng, Chongyoup Kim, Ji-Hyun Kim, Seokwon Kim, Seung Hyun Lee, Kai Choong Leong, Indranil Manna, Bruno Michel, Rui Ni, Hrishikesh E. Patel, John Philip, Dimos Poulikakos, Cecil Reynaud, Raffaele Savino, Pawan K. Singh, Pengxiang Song, Thirumalachari Sundararajan, Elena Timofeeva, Todd Tritcak, Aleksandr N. Turanov, Stefan Van Vaerenbergh, Dongsheng Wen, Sanjeeva Witharana, Chun Yang, Wei-Hsun Yeh, Xiao-Zheng Zhao, Sheng-Qi Zhou

Jessica Townsend

This article reports on the International Nanofluid Property Benchmark Exercise, or INPBE, in which the thermal conductivity of identical samples of colloidally stable dispersions of nanoparticles or “nanofluids,” was measured by over 30 organizations worldwide, using a variety of experimental approaches, including the transient hot wire method, steady-state methods, and optical methods. The nanofluids tested in the exercise were comprised of aqueous and nonaqueous basefluids, metal and metal oxide particles, near-spherical and elongated particles, at low and high particle concentrations. The data analysis reveals that the data from most organizations lie within a relatively narrow band (±10% or less) about …

Generic Strategies To Implement Material Grading In Finite Element Methods For Isotropic And Anisotropic Materials, Ke Yu

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

We look at generic strategies to transfer material grading into finite element methods. Three strategies are proposed to transfer material grading into the finite element analysis. These strategies are node-centered, element-centered, and the definition of material grading through external functions. The process to achieve each strategy is stated, and examples are used to illustrate each strategy, and to compare them. The strategies are implemented in finite-deformation nonlinear elastic analysis.

Several examples are used to illustrate the implementation of each strategy for graded isotropic materials. For these examples, the results obtained from finite element models are compared with those obtained from …

Reduction In Wick Drain Effectiveness In Typical Utah Clays, Gabriel M. Smith

Theses and Dissertations

Consolidation theory states that decreasing the spacing of prefabricated vertical drains will decrease the time required to achieve primary consolidation. Previous field tests have shown that there exists a "critical" drain spacing, which is the point at which further spacing decrease does not decrease the time of primary consolidation. This "critical" spacing is thought to be due to disturbance effects from installation of the drains. Previous studies have found that the "critical" drain spacing may be dependent upon soil layering and drain and mandrel dimensions. Thin, interbedded clay layers have been found to be affected greatly due to the smear …

Development Of A Grond-Based High-Resolution 3d-Sar System For Studying The Microwave Scattering Characteristics Of Trees, Justin Frank Penner

Theses and Dissertations

This thesis presents the development of a high-resolution ground-based 3D-SAR system and investigates its application to microwave-vegetation studies. The development process of the system is detailed including an enumeration of high-level requirements, discussions on key design issues, and detailed descriptions of the system down to a component level. The system operates on a 5.4 GHz (C-band) signal, provides a synthetic aperture area of 1.7 m x 1.7 m, and offers resolution of 0.75 m x 0.3 m x 0.3 m (range x azimuth x elevation). The system is employed on several trees with varying physical characteristics. The resulting imagery demonstrates …