Computer Simulation of Geotechnical and Hazardous Waste Investigations

Missouri University Of Science And Technology, Rolla MO

Investigators

Abstract

Earth Systems Science (40) Teachers of Geology, Geological Engineering, and Civil Engineering are challenged with the task of teaching students how to apply geological concepts to solve real-world engineering problems. While students receive ample presentation of geological concepts, engineering theory, and case histories, they receive very little practice using their knowledge in ways required in the hazardous waste and geotechnical industries. This project aims to enhance and calibrate a simulator for hazardous waste and geotechnical investigations, to test its effectiveness as a teaching tool for undergraduate and graduate instruction, and to explore its use as a research tool to probabilistically evaluate site conditions. This simulator, called BEST DrillSim, addresses the need for students to receive practical experience designing subsurface investigations and interpreting the resulting data, using the geologic concepts they have learned in class. The simulator uses real or simulated hazardous waste or geotechnical sites. The students select locations for simulated borings, interpret the data returned by the computer, and prepare the next step of investigation. The student's goal is to optimize expenses and the number of borings while determining the limits of ground-water contamination or the range and variability of geotechnical properties at the site. The instructor is provided detailed site information, including three-dimensional gif file animations of site geology, static maps of containment plumes, ground elevations, ground-water surfaces, and tabulated summaries of geotechnical and hydrogeologic parameters for each stratigraphic unit. Version 1 of the simulators, called BEST DrillSim, was developed as part of a series of Basic Engineering Software for Teaching (BEST) produced by the instructional Software Development Center at the University of Missouri-Rolla. The three site databases included in Version 1 offer a variety of geological environments for students to investigate: meandering stream alluvial sediments, coastal and shallow marine deposits, and residual soil over shale bedrock. Each site database contains a 700,000 node array, with each node point associated with a specific geologic unit. Each geological unit has a defined set of geotechnical and hydrogeological properties, which have a random variability about a central value, and which vary with depth. Each site also has associated surface topography, ground-water topography (for as many as three aquifers), and contaminant plume maps. The enhanced version (Version 2) of BEST DrillSim, completed under the current project, automatically generates sites. Hypothetical sites are generated using geological and site constraints input by the instructor, matching the specified conditions to default probability distributions of geological, geotechnical, and hydrogeological parameters, and then randomly selecting values within these probability distributions. The capability to probabilistically generate sites means that an infinite number of sites may be produced, without the labor involved in defining individual sites as in Version 1. This capability also allows exploration of probabilistic simulation of real sites, where various hypotheses about site conditions may be evaluated through Monte Carlo simulation. Evaluation of the simulator is taking place in three classes at the University of Missouri-Rolla, and by independent ers outside of the university. Electronic copies of the simulator will be distributed via CD-ROM through commercial vendors.