Abstract
This paper is based on the condition where layered argillaceous cemented sandstone as an engineering background is met by the No. 207 fully mechanized working face open-off cut (Wanli No. 1 Coal Mine). Through mechanical theory analysis and field practice, the engineering safety problem of the large-span argillaceous cemented sandstone layered open-off cut roof supporting structure was analyzed. The roof caving arch height of the open-off cut roadway in 207 working face was obtained based on the mechanical mechanism of instability and caving of the layered surrounding rock mass roof. The anchor cable suspension and bearing stability of the open-off cut roof were analyzed in terms of the layered beam structure model. Meanwhile, combining with conditions, reasonable and effective support countermeasures and key parameters are proposed for such open-off cut roadway and enhance the actual supporting engineering on-site. These research results could provide engineering reference for an open-off cut roadway with composite roof conditions featured to weak cementation and weak interlayer.
Highlights
With the gradual improvement of the mine modernization level in our country and considering the development requirements of mine safety, the development trend of largescale working face equipment has become further obvious
The cross section of the corresponding working face open-off cut roadway keeps enlarging, for which the open-off cut span increases from 5.5 m to 7 m∼10 m gradually. e argillaceous cemented sandstone layered roof has the characteristics of low shear strength and poor bond force
Zhang et al [11, 12] performed the support optimization design of a large section roadway through three-dimensional numerical simulation by using the FLAC3D. It was based on the engineering practice of the large section roadway in Zhaozhuang Mine, including a composite roof of mudstone and sandy mudstone and the shale floor. ey optimized the row spacing between the bolt and put forward an anchor-anchor cable integrated supporting parameters optimization program to match the large section of the composite roof
Summary
With the gradual improvement of the mine modernization level in our country and considering the development requirements of mine safety, the development trend of largescale working face equipment has become further obvious. 3. Mechanical Stability Analysis of Large-Span Open-Off Cut with Argillaceous Cemented Sandstone Layered Roof. Mechanical Analysis on Stability of the Open-Off Cut with Argillaceous Cemented Sandstone Layered Roof under Anchor Cable Suspension. E supported beam structure of the composite roof [32, 34,35,36] was used to construct a mechanical model for analyzing the stability of the cable suspension structure with an argillaceous cemented sandstone roof (Figure 3). 4. Research on Supporting Technology for the Large-Span Open-Off Cut with Argillaceous Cemented Sandstone Layered Roof. Based on the on-site investigation and above theoretical analysis and research, the supporting scheme was designed for the surrounding rock of the 31 upper 207 large-span open-off cut roadway of Wanli. The top bolt of each row cooperated with bamboo tray supporting. e side mesh was made of 35000 × 5000 mm flame-retardant plastic mesh, and the overlapped part between the plastic mesh patches was no less than 100 mm and bound by the double-stranded 14# lead wires into a “W”-shape. e distance between binding wires was no more than 200 mm. e auxiliary bolts were made of Φ16 × 1800 mm round steel bolts and equipped with a 120 × 120 × 8 mm tray. e spacing between rows was 1000 × 1000 mm, and the bolts of the top row were 400 mm away from the roof. e side mesh was made of 2900 × 1100 mm reinforcing mesh, for which the overlapped part of the reinforcing mesh patches was about 100 mm. e overlapped part should be bound by double-strand 14# lead wire into a “W”-shape. e spacing between binding wires should not be more than 300 mm, at the same time. e overlapped part width of the auxiliary mesh and the roof mesh was no less than 100 mm
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