Details

SPECIFICATION OF BOLTING SYSTEM

(Cir Tech 03/1993 & 06/1993) The length of the Bolt should be at least one-third of the width of roadway. However the length should normally be not less than 1.5 metre. For restricted height, coupled bolts would have to be used. A 20-22 mm diameter bolt (ribbed bar) will meet the requirements in most of the cases.

The bolting density for the thee types of roof, where bolting has been recommended, will be as given below :

(i) Poor - 1.2 to 1.5 bolts/m²

(ii) Fair - 1.0 bolt/m²

(iii) Good - 0.7 bolt/m²

At junctions, the density should be increased by 25%. The bearing plates should be not less than 15 cm x 15 cm or equivalent area. The bolt angle should generally be normal to 

the bedding plane in rectangular roadways. The bolt angle should generally be normal to the bedding plane in rectangular roadways. The rib side bolts may in certain cases be 

incline onwards.