Practice and understanding of advance support in t

Practice and understanding of advanced support of broken roof roadway

the mining depth of Suncun coal mine reaches -1100 m level, and the vertical distance from the ground is 1300 m. The faults in the mine field are relatively developed, including 26 main faults (drop of 10 ~ 450 m) and 19 large and medium-sized faults, all of which are normal faults with dip angles of 45 ° ~ 80 °, generally 65 ° ~ 70 °. The strike of the fault is NW, NE and near Sn, mainly ne. The fault is purely a public welfare layer, mainly high angle normal faults, with poor lithology. The roof and floor of some coal seams are broken soft rocks, and there are broken mudstones near the fourth floor and the eighth floor; In addition, as the depth increases, the number of faults increases, the drop increases, and the fault structure becomes more complex. Due to the influence of deep in-situ stress and ground pressure, the crushing pressure of coal and rock mass is high around the through layer tunneling, faults, fracture zones, composite roof and coal pillars. This series of products are pollution-free, low noise and high efficiency in tunneling. During the construction period, due to the loose and broken coal and rock mass, the roof is easy to fall off and fall, and it is difficult to carry out bolt support. The roof leakage needs to be penetrated, and the shed needs to be restored later. The construction is difficult and the safety cannot be guaranteed, It often causes slow construction progress, poses a great threat to safety, and also seriously affects the popularization and application of anchor bolts. In view of this prominent problem, Suncun Coal Mine adopted the advance support technology of drilling pipe joint bolts in advance during the construction of broken roof roadway, and achieved obvious results through exploration and practice in recent years

2 construction method of advance support

2.1 advance support of semi-circular arch bolting and shotcreting roadway

in case of structure, supporting coal and roof breakage, the following measures shall be taken:

① first, the permanent support of the roadway shall be supported to the heading face. Before each blasting, pneumatic drill shall be used immediately after the heading face φ 22 mm hexagonal hollow drill is used to drive a row of advanced metal pipe seam bolts into the surrounding rock at an angle of 30 ° ~ 45 ° along the contour of the roadway in the construction direction of the working face composed of the structure and composition of the electronic universal experimental machine for roadway drivage workers. The main machine of the electronic universal experimental machine is mainly composed of a base, a workbench, a column, a lead screw, a moving beam and an upper beam（ φ 33 mm × 1800 mm), and each row is generally not less than 5, with a spacing of 0.3 ~ 0.5 m. advance pipe joint bolts are used as auxiliary temporary support. When the advance support construction is completed, the drilling shall be started according to the distance of the advance support

② when drilling, the circulating footage is 0.7 m, the maximum empty roof before blasting is 0.3 m, and the maximum empty roof after blasting is 1.0 M. the soft rock part of the excavation face adopts the methods of dense drilling (the peripheral eye distance is reduced to 300 mm), reserved protective layer, less charging, etc. to reduce the damage to the surrounding rock. After blasting, first knock the side and top, and strictly implement the system of knocking the side and top. Personnel stand in a safe place with good support, use a long handle tool with a length of more than 1.5 m to remove the hanging gangue of dangerous rock (including the excavation face), and then carry out initial spraying

③ the thickness of initial spraying shall not be less than 30 mm, generally 30 ~ 50 mm. The front detection beam shall be moved forward 20 minutes after the initial setting. Personnel are strictly prohibited from entering the empty roof area during the initial spraying. Personnel shall stand in a safe place with good support to operate. One person shall hold the nozzle, and one person shall be responsible for auxiliary lighting and liaison, and observe the safety of the roof and the spraying quality. The front detection beam shall be made of 3-inch and above steel pipes, and the length shall not be less than 3.2 m; The strength of the lifting ring should match the strength of the detection beam before accelerating the exploration and exploitation of lithium resources. The anchor rod of the upper lifting ring must have enough threads, generally not less than 40 mm, to ensure the firmness of the lifting ring. The distance from the front probe beam to the end face of the heading face shall not be greater than 0.3 M. Use square wood, wood grate and top plate to press solid, and fix with wooden wedge

④ after the temporary support is completed, the permanent support processes such as drilling, hanging and installation of anchor rods are carried out under the cover of the temporary support

⑤ when the pressure increases and the deformation is serious, the roof anchor cable shall be reinforced in time, and the row spacing between anchor cables shall be 2.5 M × 2.5 m, two rows are arranged symmetrically from the middle of the roadway to both sides, the length of the anchor cable is not less than 6 m, and the lagging heading face is controlled within 0 ~ 10 m according to the pressure