Design and application of reasonable pre-tightening force of bolt and cable support in coal roadway with high roadside

The mismatch of pre-tightening force of bolt and cable in roadway side is one of the important reasons for the failure of roadway support in high coal side.This paper analyses the cause of the breaking and wounding accident of the anchor rope in the back air roadway of 30211 fully mechanized mining face in a mine, and simulates the matching relationship between the two when the roadway adopts the combined support of anchor rod and anchor rope by FLAC^3D software.The results show that when the two materials with different elongation are used in the same side of the same roadway, the load of the anchor cable with small elongation is larger and breaks first; the combined action of the anchor bolt and the pre-tightening force of the anchor cable forms different compressive stress zones on the surface and near the interior of the surrounding rock of the roadway.With the increase of the pre-tightening force, the value and range of the compressive stress are also expanding.The pre-tightening moment of anchor is set in 200-300 N·m, and the pre-tightening force of anchor cable is set in 200-250 kN, which is a reasonable matching scheme.The research results have a certain guiding significance for the design and construction of high coal roadway support.