Geotechnical / Geoenvironmental Engineering

Research Project Abstracts: 2001 - 2002

Closing the Gaps in the Regulation of Municipal Solid Waste Landfills: Defining the End of the Post-Closure Monitoring Period and the Stability of Leachate Reticulation Landfills
M. A. Barlaz and M. A. Gabr
US Environmental Protection Agency
9/99 to 9/01
The objective is to develop a plan to establish the scientific basis for defining the end of the post-closure monitoring period at municipal solid waste (MSW) landfills. Current regulations specify terminating the post-closure monitoring period 30 years after closure. While emissions are likely to continue well beyond 30 years, regulatory agencies and landfill owners lack the scientific basis to define an appropriate endpoint. In addition, the increased use of leachate recycle to enhance MSW decomposition will result in changes in the properties of decomposed refuse, increased methane emissions, more precise water management, enhanced settlement, and a need to reconsider cover stability and design.

Accelerated Flushing of Subsurface PAHs: Phase I Demonstration at the Former Lockbourne AFB Columbus, OH
M. A. Gabr
US Department of Energy/US Army Corps of Engineers through Informatics Corporation, Richland, Washington
9/00 to 12/01
The former Lockbourne Air Force Base has been in operation since the early 1940s. As a result of the site's original mission, environmental subsurface contamination was found within portions of the site during several Phase I & II Environmental Site Assessments (conducted in the early 1990s.) The main objective of this work is to implement the Well Injection Depth Extraction System (WIDE), technology for in situ remediation of the target compounds at the RPA site utilizing 35 ft x 35 ft test area.

An Evaluation of the Application of Plasma Arc Vitrification to Improve the Strength of Weak Soil and Weathered Rock
M. A. Gabr and P. Mayne (Georgia Institute of Technology)
NC Department of Transportation (NCDOT)
7/00 to 7/01
A portable plasma system will be utilized to create vitrified columns within a failed slope comprised of residual plastic clay derived from underlying weathered mudstone. The research program will be used to document the current geotechnical properties of the clay and mudstone strata, as well as the resultant igneous rock materials created after vitrification. Laboratory, field, and geophysical testing techniques will be applied for characterization of the material properties before and after the application of Plasma ArcVitrification as a ground modification approach.

P-Y Curves for Laterally Loaded Drilled Shafts Embedded in Residual Soft Weathered Rock
M. A. Gabr and R. H. Borden
NC Department of Transportation/Federal Highway Administration
7/99 to7/01
The objective of this research is to develop and validate a procedure for design and analysis of laterally loaded drilled shafts embedded in the Piedmont weathered rock profiles. The proposed procedure will be based on the P-y method of analysis in which the shape and magnitude of the P-y curves in the weathered rock profiles will be measured and defined. The research plan has three major components: a) laboratory testing program, b) field testing program and c) model development. Verification of the developed models based on the measured field and laboratory data and demonstration of the applicability of the developed design approach will be performed.

Lateral Capacity of Drilled Shafts Embedded in Soft Weathered Rock
M. A. Gabr and R. H. Borden
NC Department of Transportation
7/01 to 7/02
The overall objective of ongoing research is to define the shape and magnitude of the P-y curves appropriate for use in designing deep foundation to resist lateral loads in the Piedmont soft weathered rock profiles and to develop systematic design procedure for these types of foundations. Emphasis will be placed on performing additional field tests to investigate shaft embedment in soft rock based on a deformation criterion, while maintaining an acceptable level of safety. The results of the additional field tests, laboratory tests, as well as the rock dilatometer tests, will be used to verify the P-y design model and demonstrate the validity of the developed analysis/design procedure.

Soil Characterization for Cesium Remediation at the Battelle Columbus Laboratories Decommissioning Project
M. A. Gabr
US Department of Energy through Informatics Corporation, Richland, VA
8/01 to 12/01
The objective of the proposed testing program is to provide basic and engineering properties of the site soils with a focus on site soils attributes of importance to the implementation of the WIDE technology. In this program, properties such as soil characteristic curve, pore size distribution, cation and anion exchange capacity, soluble salts, organic carbon content, dispersion characteristic of the clay component, clay fraction mineralogy, compressibility (change of void ratio with vacuum gradient), and compaction characteristics will be evaluated. Additionally, injection of solution through the engineered unsaturated fill to overcome the vadose zone high entry pressures will be investigated.

A Unified Approach to Predicting Long Term Performance of Asphalt-Aggregate Mixtures
Y. R. Kim, R. H. Borden, and Y. Horie
National Science Foundation
9/98 to 8/01
The research objective is to develop test methods and models for predicting long term performance of asphalt concrete that can account for viscoelasticity, damage, volumetric/deviatoric coupling, temperature, and aging. The objective will be accomplished by applying the elastic-viscoelastic correspondence principle and the continuum damage theory. The constitutive model will be incorporated into the ABAQUS finite element code and used to predict the response and performance of laboratory pavements loaded by the Model Mobile Load Simulator. Nondestructive surface wave tests will be performed to determine the change in material properties due to fatigue damage growth.

Management Information Systems for Pre- and Post-incident Hazard Assessment
D. F. Laefer
Unsponsored
2001, ongoing
This research involves the creation of a seamlessly integrated management information system with GIS, CAD, and relational databases for pre-and post-incident hazard assessment for urban areas using the World Trade Center September 11, 2001, data.

Transformation of Scanned Data into Finite Element Meshes
D. F. Laefer
Unsponsored
2002, ongoing
As an extension of using scanned data for emergency response planning, transformation of the three-dimensional coordinates into finite element method (FEM) meshes is proposed. This will permit the wide-spread use of FEM for vulnerability assessment of existing structures.

Expansion Quantification of Soundless Demolition Materials
D. F. Laefer
Unsponsored
2002, ongoing
Meaningful laboratory tests for soundless demolition materials will be devised to quantify the expansion characteristics of the material.

Subsurface and Surface Soil Movements due to Tunneling in Seoul
D. F. Laefer
Unsponsored
2002, ongoing
Using collected field data for tunnel lining and surface changes, analysis of below ground and surface soil movements due to tunneling in Seoul is being done.

Somerset Plantation Building Settlement
D. F. Laefer
Unsponsored
2001, ongoing
Somerset plantation is a national historic landmark located in northeastern North Carolina and is the largest extent plantation in the state. The main house and many of the smaller, outlying buildings are currently exhibiting distress. At many locations, there is sufficient differential settlement to impact building functionality (inoperable doors and windows and sidewalk collapse). Heavy visitor traffic was proposed by the site staff as the cause of the building displacements. Site investigation identified a change in the groundwater table as the probable cause of building movement. Two potential sources of groundwater change are currently being investigated-water level management of an adjacent lake and a nearby mining operation.

Wave-induced Response and Instability of Seabed
M. S. Rahman
Unsponsored
6/96 to 12/02
Water waves propagating on the ocean creates a cyclic pressure on the ocean floor that may be significant in shallow water. This in turn induces stress and pore pressure fields in fluid-saturated seabed, which can cause instability in the seabed. The general theme of this ongoing research program has been to understand the mechanism of wave-induced seabed response and instability and to develop a predictive analytical tool to study this problem. At present, the following specific problems are being studied: effects of inertial forces on wave-induced seabed response, wave-induced response of seabed containing a gas-laden layer, and development of a simple analysis for the coupled flow and inelastic deformation of seabed including the pore water pressure generation under cyclic loading.

Load and resistance factor design (LRFD) for axial capacity of driven piles
M. S. Rahman and M. A. Gabr
NC Department of Transportation (NCDOT)
7/01 to 6/02
The main objective of this study is to develop the resistance factors for the design of driven piles in North Carolina. These factors are being developed for the unique soil types of various regions of North Carolina. The development of these factors are being attempted in the framework of "advanced reliability analysis" using the results from Pile Driving Analyzer (PDA) and static load test data embodying the uncertainty associated with soil parameters. The results from this study will lead to an implementation of the Load and Resistance Factor Design (LRFD) for piles, bringing NCDOT in compliance with AASHTO guidelines.

A Mechanistic Approach to Evaluate Contribution of Prime and Tack Coats in Composite Asphalt Concrete Pavements
A. A. Tayebali and S. Rahman
NC Department of Transportation (NCDOT)
7/00 to 6/02
The importance of proper AC layer interface bonding cannot be overemphasized for good performance of AC pavements. A strong bonding between layers is critical to dissipate shear stresses into the entire pavement structure, but lack of bonding may cause slippage phenomenon and activate distress mechanisms that will rapidly lead to total pavement failure. The objective of this study is to evaluate the effects of different prime and tack coats on the bond strength in relation to the thickness of the asphalt concrete layer. Based on the results of the study, correlation will be developed between delamination parameters and stress-strain-displacement field.