Measuring Development Mining Roof Sag

摘要

Until recently, real-time roof sag measure ments at the time of mining were not possi ble in coal mines due to equipment permissibility restrictions. Intrinsically safe miniature data acquisition systems (MIDAS) data loggers with the capability to store the large density of data generated are a new development. The combination of MIDAS dataloggers with overflow settlement measurement practices adapted from dam and embank ment monitoring by RST Instruments Ltd. (known as a liquid settlement system or LSS) were used indirectly to measure roof sag by measuring fluid pressure in water-filled tubes at four horizons in the immediate roof.