Under the deep complicated geological conditions,the coal rock tend to be broken as block rock mass,and under dynamic loading,the ultra- low friction effect is easy to be produced and the coal and rock dynamic disasters are easy to be induced with instability. The dynamic response of block rock mass under the combined effect of vertical impact load and horizontal static force was simulated by FLAC- 3D software. The mechanism of ultra- low friction effect in block rock mass was analyzed,and the influence law...