Testing procedure for the certification of underground protective cabs and canopies

A testing procedure by which underground cabs and canopies can be certified has been developed. This procedure requires the cab or canopy to be tested on a rigid platform, which in most situations can be the mining itself, and subjected to a load distributed within the middle ninth of the structure's plan view area. A displacement dial gage or an equivalent measuring device records the maximum and permanent deflections of the structure's top caused by the loading. The total applied load must be at least as great as whichever is smaller, 18,000 lb or 15 psi times the structure's plan view area. If the measured permanent deflection is less than 10% of the recorded maximum deflection, the cab or canopy can be certified by a State-registered professional engineer. The step-by-step procedure for the present testing method along with five examples of how it could be implemented are given the report. The results of the present test, which is simple to conduct, are usually conservative because factors of safety have been introduced to compensate for a loss of accuracy which must occur to gain simplicity in testing.