“Two-zone” height calculation in solid backfill mining

The breakage mechanism of roof strata under the different condition of mining with filling was analyzed, which studied the computing method of “two-zone” height in the mining with filling, It was investigated and proposed the decision procedure of “two-zone” height in the mining with filling who based the key stratum theory; the movement and destruction rule of overlying strata in work surface mining with filling was revealed by the numerical simulation; it used decision procedure of “two-zone” height in the mining with filling, empirical formula, numerical simulation, drilling detection to analyze the “two zones” height, which considered the geological and mining conditions of Changcun colliery.The results showed that the calculated results were in agreement with the experimental results; the height error of “two zones” in filling mining was large according which calculated by the traditional empirical formula.The calculated results of the new method were closest to the measured results, it provided a method for calculation of “two-zone” height in the filling surface.