Site monitoring of gangue backfill paste performance of filling replacement mining the strip coal Pillar

Normally, the filling effect is evaluated by means of surface movement observation with longer period, higher cost and more labor. To this point, on-line monitoring system of filling body performance is developed. We assess filling effect through monitoring filling body compression, force of filling body and hydration process. The monitoring results show that the compression and force of filling body located at the middle of working face is larger than that located at both ends. The compression of filling body located at the middle of working face is 104.3mm and its compression ratio is 3.85%. The force of filling body located at the middle of working face is 5.1MPa. The monitoring results show that the aggregate gradation, density and anti-compression properties of gangue backfill paste are good. The range of overburden strata affected by mining is small. The filling body can control the movement of overburden strata effectively. The maximum temperature of filling body is 54°C. The practical temperature of filling body is far above the curing temperature (20°C) in mixing proportion test, which will benefit the early strength of gangue backfill paste. This is very important for shortening solidification time and increasing productivity of filling working face.