Spill alert device for earth dam failure warning

Abstract

A spill alert device based on the monitoring of acoustic emissions (AE) has been developed, field-tested, and placed into an operational mode at several sites. This apparatus can be useful in predicting and anticipating the failure of earthen structures such as dams, waste storage lagoons, and spoil piles. With sufficient advance warning, repair of such structures becomes possible, thus avoiding possible catastrophic discharges of their contents into the environment. This report describes the fundamental mechanisms that cause soils to generate AE when placed under strain and the techniques and equipment necessary to monitor such emissions. Results of laboratory testing are shown to demonstrate a relationship between soil types and characteristics and the AE that result when such soils are subjected to applied stresses. Evidence is presented to show that AE increase as a soil approaches failure due to imposed stresses. Conversion of the laboratory apparatus to a portable system suitable for field use is documented. This equipment had an estimated cost of under $2,000 in December 1978. Results are presented for field tests of AE monitoring of 19 field sites. These results reveal potential weaknesses in some earthen dikes and stockpiles, highway fill stockpiles, and embankments and identify sites of potential failure so that corrective measures can be undertaken. This project was a 1977 recipient of one of the Industrial Research Magazine's IR-100 Awards. A number of companies are now marketing AE devices for earth structure monitoring.