Collaborative Control Technology of Crosscut Floor Heave in Soft Rocks under Deep High Horizontal Stress

Abstract

The repair rate of deep permanent roadways is about 90%, and most of which are projects treating floor heave. The deformation behaviors of crosscut were analyzed in the work according to a trackage crosscut at the shaft station of Panyidong Coal Mine in Huainan, China. Crosscut has complex characteristics such as globality, difference, and rheology under deep stress because that crosscut passes through multiple strata. The mechanism of crosscut floor heave was studied based on on-site in situ stress tests and surrounding rock composition tests. The floor heave of trackage crosscut is water swelling in the mudstone and sandy-mudstone areas where the mineral components are mainly kaolinite and illite mixed layers. In the areas of fine and medium-fine sandstone, trackage crosscut is in shear dislocation under high horizontal stress. The slip-line field theory was used to study the ultimate load and maximum failure depth of crosscut floor heave. According to the deformation characteristics of crosscut floor heave, a collaborative control technology enhancing the bearing structure of all-sided surrounding rocks was proposed, including filling of the U-shaped steel supports, shallow grouting in the all-sided surrounding rocks and deep grouting in the floor and inverted arches. A support scheme for repairing the floor was designed based on the specific engineering geology of trackage crosscut floor heave at the shaft station of the Panyidong Coal Mine. After repairing, the crosscut floor heave was monitored for 70 d. The results showed the following. (1) After repairing, the maximum cumulative floor heave was 45.3 mm, which was only 8.1% of that before repairing. (2) Crosscut floor heave changed greatly within one week after repair, with a maximum floor heave speed of 4.7 mm/d. The floor heave speed was maintained below 1 mm/d after 40 d, and the floor heave tended to be stable after 60 d. The collaborative control technology enhancing the bearing structure of all-sided surrounding rocks could control the crosscut floor heave in soft rocks under deep high horizontal stress.