9734899 Roth "Evaluation of Reliability of the Earth Resistivity Method in Thinly Mantled Karst" Sinkhole occurrences in areas of thinly mantles karst are a common cause of cost overruns during construction and failures of structures during their useful life. The frequency of these failures can be reduced by improved geotechnical site investigation prior to construction. The objective of the proposed study is to investigate and demonstrate the use of resistivity methods to increase the reliability of foundation design in karst areas with clay soils. At the present time, methods of site investigation in karst areas with clay soils are generally limited to borings and other types of intrusive probes. The reliability of these methods for locating conditions which may lead to the formation of sinkholes is poor. The research activities in this study will evaluate the reliability of the earth resistivity method as a tool for site investigation in these areas and demonstrate its use as a method to improve foundation reliability. In this study, two areas of known subsurface voids and frequent sinkhole formation will be investigated. Line surveys at a number of different spacings will be conducted using an earth resistivity meter with multiple electrodes. Anomalies indicated by the data will be confirmed using boring methods or excavation. The results of the testing will be used to develop relationships between line and node spacing and the probability of detecting an anomaly of a given size. ***
