METHOD FOR GEOELECTRIC TOMOGRAPHY OF UNSTABLE ROOFS OF COAL SEAMS Russian patent published in 1994 - IPC

FIELD: mining. SUBSTANCE: method consists in grounding of current carrying electrodes A and B and measuring electrodes M and N in two mine workings, excitation of electric field through current-carrying electrodes A and B, measuring field value through measuring electrodes M and N. In this case, electrodes are moved in compliance with preset diaphragm. All electrodes are grounded in low-resistance roof rocks. Measuring electrodes M and N are grounded in different mine workings. One of current-carrying electrodes A is grounded hear measuring electrode M. Current-carrying electrode is grounded in the working in which measuring electrode N is grounded at distance several times as large as that between electrodes M and N. Electric field is measured simultaneously by varying distance between electrodes M and N. EFFECT: higher efficiency. 13 dwg