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Norway

The machinę can be used for our ordinary sampling and vane boring operations, and also for auger borings. But it was found that a special type of sounding would be morę convenient when using a drilling machinę. This method is called a drill-pressure sounding, referring to how it* works. A 40 mm sounding point supplied with hard welded seams and extended by 33.5 mm extension rods, is screwed down in the soil at a constant speed of 3 meters pr. min, and at a constant rota-tional speed of 25 revolutions pr. min. The downward thrust necessary to keep the constant movements is registered as a curve versus the depth. The results give a good indication of the soil condi-tions, also compared with the weight sounding method. The depth capacity is limited to what resistance can be over-come by the available weight of the drilling rig. For tractor rigs the pressure capacity is 30 kN.

FIG.2.5. Drilling machinę mounted on a tractor.

Fig. 2.5 shows the drilling machinę mounted on a tractor. The picture shows extension of rods for sounding.

One of our consulting firms, Noteby A/S, has constructed a heavier eąuipment, called a multipurpose drill rig, mounted on a Muskeg tractor. They also apply a heavier drilling string, madę up of 5/4" rock drill rods, and with a 2 1/4" rock drill point. The available weight is 4 tons. The available penetration force can be increased by screwing down two earth anchors.

The rig is shown in Fig. 2.6. It may also be applied for rock control boring, auger boring and sampling. (A special paper by Andresen and Rygg will give a morę detailed description of the drill-pressure soundingO

FIG.2.6. The "Golioth" multipurpose drilling rig.

2.4 Rock control boring

In case of a morę precise determination of the rock surface, a heavy pneumatic rock drilling machinę and rock-drilling rods with Carbide tips is used.

FIG.2.7

Rock control drilling.