88娱乐城
Primary local stability risk factors:
Cut sequence: Is an outside lift sequence being used?
听
Final stump: Is an adequate final stump consistently being left in place?
听
Support: Are mobile roof supports being used?
听
Roof bolts: Is extra roof support used in intersections?
听
Global stability risk factors:
Pillar design: Is the ARMPS SF adequate to prevent a squeeze?
听
Collapse prevention: If the ARMPS SF less than 2.0 and the pillar w/h less than 4.0, either on advance or in the worked-out area, have steps been taken to prevent a massive pillar collapse?
听
Barrier pillar design: If the depth of cover is greater than 1000 ft, are stable barrier pillars (SF greater than 1.5 to 2.5) being used to separate the panels?
听
Other risk factors:
Roof geology: Is the roof at least moderate in strength?
听
Intersection span: Have entry widths and turnouts been minimized?
听
Multiple seam interactions: None anticipated?
听
Depth of cover: Less than 650ft?
听
Block size: Are the blocks uniform in size?
听
Age of workings: Is the development less than 1 year old?
听
Continuous haulage: None?
听
