What Does Free Boring Mean?
Free boring is a laser-guided microtunneling system used in stable and cohesive clay, rock and mudstone. Free boring is economical, as conventional pipes can be easily inserted into the bore. The bore self-supports and does not require insertion of a casing for continuous ground support.
Free boring is a trenchless method of pipe installation and is economical when installations are of short lengths.
Trenchlesspedia Explains Free Boring
Horizontal earth boring machines with augers are used for free boring. The length of the bore should be limited to that specified by the machine manufacturer.
Generally, lengths up to 40-feet and diameters from 2 to 12-inches can be carried out using this method. Only single auger sections should be installed at a time. Free boring should be attempted only in stable soils where no rocks are present. There are high chances of machine upset and injury to personnel exposed to the rotating augers. Since the augers are not restricted, it can possibly catch on an obstruction and cause the machine to advance unexpectedly owing to the screw action of the augers.
Another drawback is that the exposed auger can bring back soil in excess of what the cutting head is excavating. In such a case, the machine has to be stopped and the cause has to be determined prior to commencing work again.