Abstract: In response to the surrounding rock control problem of ultrahigh roadway, the ultrahigh segment of No.5205 belt transportation roadway in a mine has been selected as research object, the distribution characteristics, development law and relative evolution tendency of fracture field have been researched by UDEC numerical simulation within the height from 3.5 m to 8 m. Results show that surrounding rock fracture field has three areas: fracture transfixion area, fracture development area and microfracture area are all distributed as semi-ellipse. With the height increasing, three fracture areas depth of roof, floor and two sides increases gradually. The transformation from the microfracture area to the fracture development area and from the fracture development area to the fracture transfixion area is strengthened in roof and floor. On the contrary, the transformation from the microfracture area to the fracture development area and from fracture development area to the fracture transfixion area is reduced gradually in the two sides. Equal-stress axial ratio with different height when side-pressure coefficient equals 1.0 is analyzed. The results show that floor void reinforced area height decreases as negative exponent and two sides void reinforced area thickness increases as positive exponent with the height increasing. It is believed that bolt can control fracture slip and delay surrounding rock bulking deformation; side diagonal cable and beam can be anchored to the no fracture region in the shoulder and floor. It has stable and reliable anchor foundation and can squeeze the fracture transfixion area in middle part of the side. Based on this, the combined support technology of high strength and high pre-stressing bolt net bar & diagonal cable and beam is proposed. Super-high roadway will reach self-stabilization after it was dig out after 10 days. Roof-to-floor relative convergence is 104 mm, with two sides relative convergence 150 mm and total roof separation 3.5 mm.

Key words: thick coal roof, super-high, roadway, fracture, support