Forepoling is a method of supporting a weak roof of a mine or a tunnel, used traditionally in soft, loose, or caving ground. To make use of this method, poles, timber, steel tube, or slabs are driven into the ground before or during excavation. The method has been used for centuries, both in smaller mines as well as larger tunneling operations. Along with time, forepoling has of course also developed as a method and the old wooden supports have been replaced with more sustainable and rigid supports made of metal. These newer supports are capable of supporting the tunnel roof even under broken rock conditions.
However, even broken rock is not an obstacle for tunneling when you are using Robit® Casing System. Made for the modern iteration of forepoling, nowadays also referred to as a “tube umbrella”, the casing system offers a holistic system for the work. The drilling system consists of casing tubes, which are drilled through the overburden in the shape of an umbrella, therefore supporting both the sides and the roof of the tunnel equally. Once in place, the drill is removed, and the casings are filled with grouting to strengthen and solidify them even further. The Robit® Casing System allows for easy driving of the casing tubes into the ground with low torque demand and is, quite naturally, fully compatible with Robit drilling bits and rods.
Robit® Casing Systems mostly used in forepoling are RoX+ 88,9/8, RoX 114,3/10, and RoX 139,7/10.
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