Shobha K. Bhatia

Comparative study of bubble point method and mercury intrusion porosimetry techniques for characterizing the pore-size distribution of geotextiles

Abstract In this paper, two simple and rapid techniques for evaluating the pore-size distribution of geotextiles are compared: the bubble point method and mercury intrusion porosimetry. Both of these techniques have successfully been used to measure the pore-size distribution of various materials. These techniques, however, measure different and unique porometric characteristics of materials. The bubble point method measures through-flow pores while the mercury intrusion method measures the volume of pores. In this paper, test results of both bubble point and mercury intrusion methods for a wide variety of geotextiles are presented. In general, the mercury intrusion pore-size distributed results showed much larger pores in the geotextiles than did the bubble point method. Overall, the mercury intrusion method was unable to distinguish between geotextiles of different manufacturing processes and various thicknesses. The bubble point method, on the other hand, was able to distinguish between geotextiles of different manufacturing processes and of various thicknesses, as long as the cross-sections of the geotextiles varied.

The Verification of relationships for Effective Stress Method to Evaluate Liquefaction Potential of Saturated Sands

The constitutive relationships proposed by Finn, Lee and Martin (1977) for the effective stress analysis of saturated sands during earthquakes are studied. The basic assumptions of their porewater pressure model appears to be well founded. There is a strong verification of a unique relationship between volumetric strain in drained tests and porewater pressures in undrained tests for both normally and overconsolidated sands. An important point to emerge from this study is that the rebound modulus used in converting the volumetric strains to porewater pressures should be measured under dynamic conditions. The porewater pressure model predicts successfully the porewater pressure response under undrained conditions for uniform and irregular cyclic strain and stress histories. When the porewater pressure model is coupled with a non-linear stress-strain relationship in effective stress analysis, i t predicts real i s t i c porewater pressure response in undrained tests for cyclic stress histories representative of earthquake loading. Results suggest that strain-hardening effects do not occur unless the sand i s allowed to drain. A new porewater pressure model based on endochronic theory is presented in which the porewater pressures are directly related to dynamic response parameters. This approach bypasses the need for converting volumetric strains to porewater pressures. The proposed formulation relates porewater pressure to a single monotonically increasing function of a damage parameter. This parameter allows the data from constant strain or stress cyclic loading tests to be applied directly to predict the porewater pressure generated in the f i e l d by irregular stress or strain histories due to earthquakes. This formulation is an extremely efficient way of representing a large amount of data and can be easily coupled with dynamic response

Bridging the Gap Between Engineering and the Global World:A Case Study of the Coconut (Coir) Fiber Industry in Kerala, India

Abstract Over the last two decades, globalization has had a profound impact on how we view the world and its sustainability. One group of professionals that lies at the heart of sustainability is the engineers. Engineers are trained problem solvers, required to implement technical solutions and are at the forefront of the development of new technologies. Although engineers play a critical role in sustainability, traditional engineering programs typically only focus on the technocentric and ecocentric dimensions of sustainability, providing little training on the sociocentric dimension. With more and more interest in sustainability, it is becoming increasingly important to also provide engineers with an awareness of sociocentric issues and the necessary skills to address them. The aim of this book is to provide engineering educators with a real-life case study that can be brought into existing courses to help bridge the gap between engineering and the global world. The case study focuses on how our enginee...

“If These Women Can Do It, I Can Do It, Too”: Building Women Engineering Leaders through Graduate Peer Mentoring

To address the dropoff of women in engineering at the graduate level, the Women in Science and Engineering (WiSE) program at Syracuse University collaborated with the Graduate School and Colleges of Engineering and Computer Science and Arts and Sciences to create a program for women graduate students in science and engineering. This paper provides an overview of available data on women in engineering and of the barriers they encounter. It then discusses the authors’ experiences with the WiSE Future Professionals Program (WiSE-FPP). Assessment data showed that WiSE-FPP provided a strong peer support network for program participants and gave the women an opportunity to engage with other women in STEM going through the same experiences. The peer mentoring offered by the program helped address barriers of isolation and the lack of successful women role models at the graduate level.

A comparison of test methods adopted for assessing geotextile tube dewatering performance

Geotextile tubes have successfully been used by virtually every industry today to dewater a variety of sediments, slurries, by-products, and wastes. Despite this, the dewatering industry currently lacks uniformity in regards to establishing testing standards and assessing dewatering performance. Prior to full-scale tube deployment, lab and/or field tests are typically performed to evaluate performance. Preliminary bench tests such as the falling head test (FHT) and pressure filtration test (PFT) are often used to evaluate candidate polymers and dewatering efficiency. The mid-scale hanging bag test (HBT) and geotextile tube dewatering test (GDT) may then be used to visualize the dewatering process and evaluate the selected polymer. There is currently no industry standard, however, and numerous variations in testing programs, methods, and data interpretation exist. Before advanced studies can be undertaken, a common framework for data interpretation must be created by standardizing testing programs. Using a fine grained, non-plastic soil and woven geotextiles, this study aims to examine and compare the bench-scale and mid-scale test methods adopted for assessing dewatering performance. In addition to standardized testing programs, the need exists for estimating geotextile tube dewatering rates. This study proposes a theoretical model using Darcy’s law and the Kozeny-Carman equation which allows for an estimation of dewatering time.

Evaluation of geotextile filter in a collection system at fresh kills landfill

The New York City Department of Sanitation has retained consultants to design a leachate collection system for the Fresh Kills Landfill in New York City. Fresh Kills Landfill is regarded as the worlds largest landfill. Because of an Order on Consent the landfill is required to have a leachate collection system by 1996. Design of the collection system includes a trench backfilled with granular material wrapped in a geotextile filter. The geotextile filter will be a critical component of the collection system and will be designed to meet soil retention and permeability requirements for the system. An existing leachate collection trench with a non-woven geotextile filter was constructed at the landfill in 1988. This collection trench and geotextile filter were exhumed, sampled and analyzed in 1993 to determine the effectiveness of the geotextile filter. Information gained from this study was utilized for the design of future leachate collection systems. Results of this study will be the subject of this paper. This study was unique in the sense that a geotextile filter was used for the first time in the collection trench at the Fresh Kills Landfill. In addition an evaluation of its performance had not been investigated before. The geotextile filter was analyzed to determine the impacts of burial and filtration of leachate in a landfill environment on the hydraulic and mechanical properties of the material. Also, the potential for biological growth on the geotextile filter was investigated. Results of this study identified minor clogging of the geotextile filter due to soil particle retention within the pores of the non-woven material. A slight reduction in permittivity was observed due to particulate clogging.

Engineering: Women and Leadership

Abstract In this book we explore a sea change occurring in leadership for academic women in the sciences and engineering. Our approach is a two-pronged one: On the one hand, we outline the nature of the changes and their sources, both in various literatures and from program research results. On the other hand, we specify and provide detail about the persistent problems and obstacles that remain as barriers to women’s full participation in academic science and engineering, their career advancement and success, and, most important, their role as leaders in making change. At the heart of this book is our goal to give some shape to the research, practice, and programs developed by women academic leaders making institutional change in the sciences and engineering.Table of Contents: Women in a New Era of Academic Leadership / Background: Academic Leadership for Women in Science and Engineering / Gender and Leadership: Theories and Applications / Women in Engineering Leadership Institute: Critical Issues for Wom...

Performance indices for unidirectional flow conditions considering woven Geotextiles and sediment slurries

Geotextile tubes have successfully been used to dewater a wide variety of low percent-solids sediments, slurries, by-products, and wastes. Because existing geotextile filter criteria have limited applicability in the geotextile tube environment, researchers and industry practitioners have adopted numerous indices to measure the retention and dewatering performance of geotextile tubes. As a result, data are published in many different forms using dissimilar performance criteria. Many of these performance measures have limited value, are difficult to interpret, and depend greatly upon material conditions and experimental methods. Using a fine grained nonplastic soil, woven geotextiles, and the pressure filtration test (PFT), this study aims to discuss the relevance and limitations of the most commonly used geotextile tube performance indices. In light of these limitations, recommendations are made for the adoption of more appropriate indices for evaluating performance.

ANALYSIS OF A FAILED BASAL REINFORCED EMBANKMENT

An interesting failure involving geosynthetic basal reinforcement for embankments constructed on soft soil occurred at the Fresh Kills Landfill located on Staten Island, New York. The failure occurred in two stages, in May 1997 and April 1998, respectively. In this study, an attempt has been made to model the embankment from this case history using finite difference software - FLAC (Fast Lagrangian Analysis of Continua, Itasca Consulting Group, 1996). The goal of such a study is to develop the finite difference model as an approximate design tool for future reinforced embankments. FLAC is a two-dimensional finite difference code that uses an explicit time-marching method to solve governing field equations. The paper presents the results of such an analysis and compares them to the field results. Various stages of construction are simulated by applying different model loading conditions at different stages of the analysis. The development of excess pore water pressures with staged construction are captured by using the undrained mode of analysis. The limits of failure and zone of movement are found to be strikingly similar to the field observations. It is expected that the proposed research will contribute to the state of the art of analyzing and designing embankments reinforced with geosynthetics in basal layers.

Sustainable Management of Dredged Sediments and Waste Using Geotextile Tube Dewatering System

In the past decade, geotextile tubes have emerged as a new technology for dewatering high-water-content dredged sediments from water bodies, by-products, and wastes. These slurry materials are often contaminated and threaten environmental resources if improperly managed. Geotextile tubes present a means to manage these materials in an environmentally responsible and sustainable manner for industrialized and developing countries alike. Keeping sustainability in mind, biodegradable materials and the viability of natural geotextiles for the dewatering and containment system need to be explored. At Syracuse University, the research team has been assessing the viability of using biodegradable geotextiles, natural flocculants, and cellulosic materials for the geotextile tube application. The results, based on both small-scale and large-scale tests, are very promising. This paper provides an overview summary of our studies.