Annual Report,2009 - Directorate General of Mines Safety
Annual Report,2009 - Directorate General of Mines Safety
Annual Report,2009 - Directorate General of Mines Safety
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DGMS <strong>Annual</strong> <strong>Report</strong>, <strong>2009</strong><br />
(d) Straightness :-<br />
The Ro<strong>of</strong> Bolt shall be straight without any joint, welding, deviation or deflection.<br />
However if the deflection or deviation cannot avoided due to practical reason, it shall<br />
not be more than ± 0.01% per meter length <strong>of</strong> the bolt.<br />
(e) Rib :-<br />
The Rib <strong>of</strong> the Ro<strong>of</strong> Bolt shall be as per the design <strong>of</strong> the rib with an objective to<br />
maximize the surface area without reducing the core diameter <strong>of</strong> the ro<strong>of</strong> bolt and<br />
having maximum grip with the grout. However the height <strong>of</strong> the rib shall be kept<br />
within 2.5 to 5% <strong>of</strong> the core diameter <strong>of</strong> the ro<strong>of</strong> bolt.<br />
2.0 Physico-mechanical Properties ;-<br />
(a) Steel for the Ro<strong>of</strong> Bolt :-<br />
The Ro<strong>of</strong> Bolt shall be <strong>of</strong> thermo-mechanically treated (TMT) rebar manufactured<br />
from MS Grade Fe-500 or above for use with cement grout and FE-650 or above for<br />
use with resin. The Tensile Strength <strong>of</strong> Fe-500 Grade or equivalent Steel shall not be<br />
less than 500 ± 10 MPa and that <strong>of</strong> Fe-650 Grade or equivalent Steel shall not be less<br />
than 650 ± 10 Mpa respectively.<br />
(b) Yield Strength <strong>of</strong> Steel :-<br />
The Yield Strength <strong>of</strong> the Steel shall not be less than 10 to 20% <strong>of</strong> the Ultimate<br />
Tensile Strength (UTS).<br />
(c) Shear Strength <strong>of</strong> Steel :-<br />
Shear Strength <strong>of</strong> the Steel shall not be less than 50 ± 5% <strong>of</strong> the Ultimate Tensile<br />
Strength (UTS).<br />
(d) Elongation :-<br />
The elongation <strong>of</strong> the ro<strong>of</strong> bolt under its designed load shall be within 12 to 18% <strong>of</strong><br />
the length <strong>of</strong> the bolt.<br />
3.0 Chemical Composition :-<br />
Chemical Composition <strong>of</strong> the steel for manufacturing <strong>of</strong> the ro<strong>of</strong> bolts varies<br />
according to the requirement <strong>of</strong> strength characteristics and specific applications given<br />
by the ro<strong>of</strong> bolts manufacturer and the end user. However certain chemical<br />
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