Impact wedge method over the collapse column practice

Under the group Wu Tun coal mine coal in Shandong Province north wing deepening, the main north wing transportation roadway Central Belt Lane, in the repair process, the case of a head-caving zone, the area surrounding rock caving soft broken rock cemented between poor It is judged that the structure is a collapsed column that has been exposed during the mining of the upper group of coal, and does not conduct water when exposed. In order to ensure the safety of construction, it is necessary to select safe and effective construction methods according to the actual situation of the site, analyze the characteristics of the shed method and the wedge method, and determine the construction using the wedge method.
1 shed construction Because the anchor net spray support can not effectively control the roof of the landing zone, it is decided to first adopt the erection of the steel shed and erect the raft to pass the collapse column.
1.1 Before the construction process, the roadway anchor net (sand) spray combined support will be carried out within 3m after head-on and head-on, and the temporary support beam and anchor net (sand) spray combined support will be adopted during the excavation construction. Shelf support. The roadway is 4.6m wide, the shed leg is 3.8m long, and the shed beam is 4.3m long.

Before the probe 50mm thicker steel production, with the beam wall thickness 5mm, length of 4.0m, with a metal bolt and fixing rings, each beam before the probe using a pair of rings (rings with a diameter not less than 18mm of steel produced) , 6 fixed points must be tightened with screws. When the front beam cannot be used normally due to the roof roofing, the wooden point column is used to support the temporary support of the steel mesh. The bottom of the wooden point column must be padded and cushioned. The top of the metal mesh roof should be covered. The diameter of the wooden point column should not be less than 200mm. The top of the roadway and the gang are all supported by anchor net (sand) spray, and the same strong threaded bolts of 18mm×2200mm are used. The spacing between the anchors is 800mm×800mm, and each anchor uses 2 volumes of MSCK2550 resin rolls. The anchoring force is not less than 60kN, the pre-tightening torque of the anchor is not less than 120N·m, and the thickness of the shot is 100mm. The strength level of cement mortar is required to be not less than M10. According to the method of 2-1-2, the anchor cable is supplemented on the top plate, and the bird's nest anchor cable of 15.24mm×5300mm is used. Each anchor cable uses 4 volumes of MSCK2550 resin powder, the anchoring force is not less than 200kN, and the anchor cable is exposed 150. ~250mm, the anchor cable spacing is 2.4m before and after, and the left and right is 4.0m (Figure 1). When the top plate is broken and difficult to control, the support can be appropriately encrypted.

The steel shed is made of 11# mining I-beam. The shed beam length is 4.4m, the shed leg length is 3.6m, the steel shed upper mouth is 3.9m wide, the lower mouth is 4.3m wide, and the shed leg depth is 0. .2m, the angle between the shed leg and the bottom plate is 87°. The steel shed is erected at a distance of 1 m on the roof stratum stable area, and the steel shed is erected at an interval of 0.5 m on the top plate in the unstable area of ​​the overburden layer (ie, within the collapse column). When reinforcing adjacent steel sheds, 18kg/m waste rails are laid in the direction of the roadway in the direction of 0.5m, and the length is 1.2m. The metal mesh is laid on the rails, and the derricks are erected on the metal net for the roof. The pine wood with a square wood size of 150mm × 150mm × 1200mm is used, and the nails are fastened and fastened with wooden wedges.
According to the above method, 14 steel sheds were set up, 7 of which were 1m apart, 7 were 0.5m apart, and the length of the roadway passing through the collapsed column was 7m.
1.2 There are problems in the construction of the shed. Through the construction, it is found that the following problems exist when passing the collapsed column according to the construction method of the shed support: 1 The roof has a large landing height, and the maximum roadway height is 8m, which is not conducive to safety management; Large amount, long time for exit; 3 roadway has a large waste section, large anchor net support section; 4 square wood consumption is large, support cost is large; 5 construction progress is slow, overall cost increases.
2 wedge construction through the collapse column
2.1 Construction steps Construction Drilling→Incorporating 2吋 steel pipe into the borehole by manual wedge method→Drilling and blasting construction (using the wind raft to gradually enlarge when the surrounding rock is soft and broken)→The top gang adopts anchor net support→ Erect permanent steel shed → double metal mesh outside the steel shed → shotcrete support.
2.2 Construction Technology (1) Use ZLJ-350 coal mine tunnel rig , and use 75mm drill bit to drill 18m horizontally into the upper and lower rows until it passes through the landing zone, then pour 2 吋 steel pipe into the drill hole, drill row With a distance of 100mm and a spacing of 200mm, the welding points of the steel pipes in the adjacent boreholes are evenly staggered, and the exposed length of the steel pipes is 1m.
(2) When drilling and blasting, the circulating footage is controlled at 0.8-1.0m, the roadway is 4.6m wide, and the roadway is 2.8m high.
(3) When the surrounding rock is hard and stable, the anchor net is selected with the same strong thread anchor. Each anchor uses 2 rolls of SCK2550 anchoring agent. The spacing between the bolts is 800mm×800mm, and the anchoring force is required to be no less than 60kN. The pre-tightening torque is not less than 120N·m; when the soft stability of the surrounding rock is poor, the 42mm×2200mm pipe joint anchor is used, and the spacing between the anchors is 800mm×800mm.
(4) The welding of the old rails between the steel sheds is strengthened. The spacing between the slab beams and the shackles is 1000mm. The shed legs are reinforced with 18mm×2200mm anchors and steel plates (at least 2 reinforcement points per shed leg). Double-layer metal mesh is laid on the shed beam and outside the shed leg. The metal mesh specification is 4.5mm×1000mm×2000mm, the lap joint is not less than 80mm (1 grid), and the double metal mesh is staggered halfway. Grid overlap to prevent large meteorites from falling.

16 # galvanized iron wire metal mesh between each bifilar breasted diamond banding (pitch 160mm). The metal mesh is externally reinforced with square wood and wooden wedges, and finally the spray is closed. The required spray thickness is not less than 100mm, and the mortar strength grade is not less than M10. A total of 36 steel sheds were erected, which effectively controlled the roof and reduced the height of the roof. The construction is shown in Figure 2.

3 Conclusions (1) The traditional shed method has certain limitations in the caving area. When the roof area is large, the cost of support is large, the construction progress is slow, and it is not conducive to safety management.
(2) The construction method of the wedge is mainly to support the roof of the roadway through the steel pipe, control the soft surrounding rock to prevent large-scale fall, reasonably and effectively control the height of the roadway, and timely and effectively adopt the anchor net support and the support of the shed. Not only reduced support costs, accelerated construction progress, but also ensured safe construction.