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Mileage (m) | Description of roadway damage |
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15∼17 | Flexible formwork wall is inserted upward |
23, 24, 58 | The coal body at the bottom of the coal pillar side is extruded 30–50 cm, and the ladder beam is broken. |
69 | Fracture of the ladder beam in coal pillar side. |
78 | Flexible formwork wall bulge phenomenon. |
82∼84, 100 | Fracture of the ladder beam in coal pillar side. |
103∼105 | Metal net at the lower part of coal pillar side cracking, ladder beam fracture, and flexible formwork wall cracking. |
113 | The bolt of the coal pillar side failed, and the cables were laid beside it. |
118 | Fracture of the ladder beam near the second bolt at the bottom of coal pillar side. |
132∼138 | Cracking of entry floor. |
151∼154 | Two bolts in the middle of coal pillar side are pulled out by the mining stress. |
163 | Anchoring cable for pillar reinforcement has been removed in later period. |
175∼180 | Extrusion and crushing at shoulder corner of the roof and coal pillar side is serious. |
188 | Unanchoring of the third bolt from the bottom of the coal pillar side. |
190–214 | Cracking of entry floor. |
198∼201 | Four rows of ladder beams were broken in the middle and lower parts of coal pillar side. |
213 | The flexible formwork wall cracks in a 3-square range, the ladder beam at the bottom of the coal pillar side was broken, and the roof protruded seriously. |
221 | Two failure bolts in the middle of coal pillar side. |
229∼232 | The upper and lower parts of the flexible formwork wall fall into the bag. The height is 1.2 meters, and the length is 4.5 meters. |
239 | The second bolt dynamometer reading at the bottom of the coal pillar wall is 24 MPa, which is abnormal; the flexible formwork wall cracks, and the middle part falls into the bag. |
247∼253 | The damage and deformation of coal pillar side are serious, which are mainly affected by primary mining and adjacent chambers. |
259∼267 | Roof breakage and subsidence are very serious, especially near the side of the coal pillar. |
276 | Unanchoring of the third and fourth bolts from the bottom of the coal pillar side. |
296 | Unanchoring of the third bolt from the bottom of the coal pillar side. |
308 | Unanchoring of the second bolt from the bottom of the coal pillar side. |
311, 312 | Unanchoring of the second bolt from the bottom of the coal pillar side. |
320∼350 | The upper part of flexible formwork wall badly bulge phenomenon. |
334∼336 | Flexible formwork wall with bulge phenomenon, bulging range is 2 meters. |
352∼355 | Cracking of the flexible formwork wall is serious. |
358 | The second repaired cable at the bottom of the coal pillar side has failed. |
399∼406 | Cracking of entry floor. |
413∼422 | There are timbers to strengthen support in this area, and there are chambers nearby. |
476∼479 | Over-excavation of coal pillar side is serious, and the cross section is large and irregular. |
537∼541 | The roof is broken seriously, the displacement is large, and the flexible formwork wall has bulging problem. |
581 | Unanchoring of the third bolt from the bottom of the coal pillar side. |
583 | Unanchoring of the second bolt from the bottom of the coal pillar side. |
620 | The upper part of the flexible formwork wall bulges and cracks, and the third anchor bolt is removed from the bottom of the coal pillar side. |
630∼640 | Water accumulation in entry and floor cracking. |
652 | The upper part of the flexible formwork wall is bulging within 2 meters. |
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