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Tunnel construction techniques
Published in David Chapman, Nicole Metje, Alfred Stärk, Introduction to Tunnel Construction, 2017
David Chapman, Nicole Metje, Alfred Stärk
HDD can be used to install pipelines through most soil or rock conditions both above and below the water table if the cutting tools, drilling rate, fluid pressure and flow rate are configured correctly. One of the key differences between drilling through soft ground and hard rock is the drilling head configuration and reaming devices. When drilling in soft soils, ‘chisel’ type drill heads are used (see Figure 5.95b) and the drilling rig provides thrust and rotational forces to the head. In order to drive in a straight line, the rods are continuously rotated as they are pushed forwards. To navigate curves, or to change alignment, the rotation is stopped and the drill rods are just pushed forwards (in this case, the forces on the angled drill head cause the head to deviate from its current direction). When drilling in rock, drilling bits are used (Figure 5.96). The drilling rig again provides thrust and rotational forces to the head, but, in addition, a mud-motor behind the drilling bit powers the cutting tool. A mud-motor uses the force of the drilling mud being pumped to the head to turn the drill bits. In order to navigate curves, once again the rotation is stopped and the drill rods are pushed forwards. However, in this case, a bent-sub arrangement located behind the cutting tool causes the drill head to deviate in direction (Figure 5.97).
Trenchless Equipment
Published in John E. Schaufelberger, Giovanni C. Migliaccio, Construction Equipment Management, 2019
John E. Schaufelberger, Giovanni C. Migliaccio
As the pilot hole is being drilled, bentonite drilling mud is pumped down the center of the drill rods. The drill head consists of either a jetting head or a purely mechanical drill bit. In the jetting head, small-diameter, high-pressure jets of bentonite slurry actually cut the soil and facilitate soil removal by washing the cuttings to the surface. When a drill bit is used, the bit can be driven by a down-hole mud motor, located just behind the drill bit, from energy derived from the pumped drilling mud. The bentonite also functions as a coolant and facilitates soil removal.
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Published in C.P. Chugh, Ken Steele, V.M. Sharma, Design Criteria for Drill Rigs: Equipment and Drilling Techniques, 2020
C.P. Chugh, Ken Steele, V.M. Sharma
Two drilling systems are suitable for deflection drilling under the conditions outlined above: (i) a conventional core-drill/mechanical wedge system or (ii) alternatively a positive displacement (mud motor) drill/bent-sub system.
A method to collect representative samples from water-driven percussion drilling techniques: examples from RoXplorer® coiled tubing drill rig
Published in Australian Journal of Earth Sciences, 2022
B. van der Hoek, F. Blaine, D. Giles, C. Tiddy, M. Mostofi, S. Soe
Drilling fluid has key roles for percussion coiled tubing drilling: (1) to drive the down-hole hydraulic tools, including a mud motor combined with (a) a rotary bit for unconsolidated cover material or (b) a hydraulic hammer and percussion bit for competent rock; (2) to transport the cuttings out of the drill hole; (3) to control fluid and cutting loss in unconsolidated and fractured formations; and (4) to provide drill-hole stability in unconsolidated formations and reactive shale.