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(Image: Soil removal technique - auger boring) In auger boring, called horizontal thrust boring according to ATV-A 125E [ATVA125:1996], the soil and/or rock, according to EN 12889 [DINEN12889:2000], is "excavated by a rotating cutting head attached to an auger which continuously removes the spoil," (Bild 5.2.3). The pipe is always made of steel and besides its task as a jacking pipe; it has the additional function of a screw conveyor guide pipe. The … |
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In trenchless technology for installation of cables and pipes, two types of machines are in use at present and these differ in their method of operation and sequence as follows:
The cutting heads are equipped with hard metal cutting edges or tungsten carbide inserts. Both rotary-percussive process variants possess the option … |
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The hammer drilling with eccentric cutting head corresponds largely to the auger boring method (Abschnitt … |
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The NUMA Hammer Champion H is based on dry spoil removal with a spiral conveyor. The cutting head consists of two parts, the inner cutting head, which is directly connected with the down-the hole hammer (centre bit) and an outer cutting ring (ring bit) (Bild 5.2.4.3.1). The ring bit is welded to the steel pipe point at the start of the boring. Its purpose is the profiling (recutting) of the borehole to its final diameter and for transferring the … |
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In the ROTEX Symmetrix HZ-system (Bild 5.2.4.3.2), the spoil removal is achieved by means of an auger. As for the NUMA Hammer Champion H, the percussion cutting head is made in two parts (pilot bit and ring bit). However, in this case, the outer ring bit welded to the steel pipe can rotate (Bild 5.2.4.3.2) (Bild 5.2.4.3.2). (Image: Hammer drilling with ROTEX Symmetrix HZ 406 system (borehole diameter 432 mm) over a length of 193 m [FI-Rotex] - View … |
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(Image: DOSCO MULTIDRILL [FI-Dosco]) The working principle of the DOSCO MULTIDRILL (Bild 5.2.4.3.3) [FI-Dosco] is mostly identical with the NUMA Hammer Champion H. Depending on the geological and hydro-geological limiting conditions, as well as the jacking length, either mechanical spoil removal by means of an auger or air (gas) flushing is possible. According to the manufacturer's information, this hammer drilling plant is used for jacking steel pipes … |
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The SST method (SST = Super Striker Tunnelling) [FI-Asanu] (Bild 5.2.4.3.4) (Bild 5.2.4.3.4) (Bild 5.2.4.3.4) (Bild 5.2.4.3.4) deviates in the method of operation and cutting head design from the previously mentioned methods. The transport of the spoil is carried out in the region of the down-the-hole hammer by means of compressed air and from there to the starting shaft by means of an auger (Bild 5.2.4.3.4).
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In hammer drilling with concentric cutting head, a rotary-percussive operating and pneumatically driven down-the-hole hammer loosens the subsoil and, depending on the type of machine, is continuously transported either by means of a spiral conveyor (auger) or by means of air (gas) flushing. The piping is connected with the cutting head and is jacked by means of a part of the impact energy generated by the hammer. This process is supported by the … |
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The main components of the equipment for hammer drilling consist of:
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Because the pipe is installed along the boring and because of the rotary-percussive or percussive drilling, hammer drilling is especially advantageously used in groundwater-free, less stable and very often inhomogeneous layers and strata with inclusions of rubble, cobbles and boulders or generally in conglomerates with soft binders (clay), as well as in rock with uniaxial compressive strengths up to 200 N/mm2 (all classes F to DIN 18319 [DIN18319:… |
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According to EN 12889 [DINEN12889:2000], "hammer drilling uses a percussive hammer mounted at the cutting head in the excavated bore with or without a sleeve. The spoil is removed mechanically by water or compressed air. Hammer drilling may be used in loose ground and rock" (Bild 5.2.4). (Image: Soil removal technique - hammer drilling) Hidden behind this definition is a large spectrum of different types of machines used in drilling or boring techniques, … |
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When using horizontal jacking with reamer, according to EN 12889 [DINEN12889:2000], "soil is displaced by pushing a rigid pilot rod. The new pipeline is installed by pulling it behind a rotating reamer." According to EN 12889 [DINEN12889:2000], a reamer is understood to be "a cutting head attached to the end of a drill string or pilot rod to enlarge the pilot diameter during a pull-back or pushing operation, to enable a pipe or pipes to be installed." |
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If the required borehole diameter for the pipe to be installed exceeds 200 mm (in exceptional cases 300 mm), or if the subsoil is not suitable for an application of soil displacement techniques, or if soil dislocation in the vicinity of the jacking process must be avoided because of existing structures, then use is made of the soil removal techniques (Bild 3.1). In soil removal techniques, steel pipes are jacked either dynamically or statically from … |
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For unmanned, non-steerable techniques (Abschnitt 3.1), the directional accuracy of the boring and thus the positional accuracy of the line(s) is influenced by the subsoil conditions (inclusions, strata, etc.), the jacking length, and the exact alignment of the boring plant and, when jacking pipes by pressing in or ramming in, by careful positioning and guiding of the first pipe piece as well as the exact angles of the end faces of the trailing pipe … |
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The steerable displacement hammer (Bild 6.1.1) possesses a stepped displacement head (steering head) situated in a housing. It can be slant adjusted and can be diverted for a desired directional correction by rotating the torsion-stiff compressed air hose by hand into the required direction (Bild 6.1.1) (Bild 6.1.1) [Ramei00]. With a housing diameter of 75 mm and a length of approximately 1.70 m, the steerable displacement hammer GRUNDOSTEER is able … |
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The STEUERBARE ERDRAKETE CM-98Z ("steerable soil rocket") (Bild 6.1.2) possesses a displacement head slanted on one side (Bild 6.1.2) (Bild 6.1.2) which, by rotating the trailed drill string by hand (Bild 6.1.2) or with the aid of a hydraulic thrust/rotating unit (Bild 6.1.2) can be brought into the desired position for course correction [NN98d] [NN98e]. The STEUERBARE ERDRAKETE CM-98Z is used for straight line bores with a diameter of 115 mm and … |
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Apr 03, 2007 Trenchless Technology for Installation of Cables and Pipelines Unmanned, steerable techniques - soil displacement techniques The steerable impact moling (steerable IM) (Bild 6.1.1) corresponds in principle to the non-steerable impact moling (Abschnitt 5.1.1). In trenchless installation, a sensor (sonde) is situated in the front housing part of the displacement hammer and this is localized by means of the Walk-Over method and makes possible the determination of the position, depth, gradient and roll of the displacement hammer [Hesse94]. At present, there are two method variants … |
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(Image: Pneumatically driven displacement hammer - structure and method of operation [FI-Vick]) A pilot bore is installed after determining the line and gradient for the line(s) to be pulled-in. For this purpose, the drilling machine is positioned on the surface and a borehole is drilled at an angle of 5° to 15° (Bild 6.2). Alternatively, the drilling machine can be installed in a starting shaft (Bild 6.2). The compressed air required for propulsion … |
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(Image: Expansion hammer with expansion sleeves for various borehole diameters [Arnol93]) This phase is characterized by the single or multiple pulling-back of the hollow drill rod string to the entry point or the starting shaft with simultaneous expansion of the borehole to a maximum diameter of 250 mm. For this purpose, a further, modified, displacement hammer (expansion hammer) is connected to the drill rod string at the exit point or the target … |
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After the last expansion bore the prepared line(s) coupled to the expansion hammer is (are) pulled in from the target point or shaft through the borehole. Detailed information of the pulling-in process is found in 2nd volume of this book. |
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The same steps are required for carrying out the process as for the Horizontal Directional Drilling with liquid or gaseous drilling fluid which are:
The soil displacement principle is used for the pilot bore as well as for the expansion bore(s). |
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(Image: Drilling machine (PITMOLE) with water tank [Arnol93]) The following are included in the basic equipment for horizontal drilling with displacement hammer:
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Horizontal drilling with displacement hammer is used principally in dry or moist displaceable soils of soil class L to DIN 18319 [DIN18319:2000] (Abschnitt 4.3.5.6) for boreholes with a diameter up to 250 mm and jacking lengths up to 100 m for pulling in one or more line(s) with a maximum DN/OD 180 [Arnol93] [FI-Welsi]. Drilling with radii of ≥ 20 m are possible with normal drill rods of 2.0 m and dA = 44 mm [Arnol93]. The Walk-Over method used makes … |
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Apr 03, 2007 Trenchless Technology for Installation of Cables and Pipelines Unmanned, steerable techniques - soil displacement techniques Horizontal drilling with displacement hammer is a combination of rotary-percussive dry drilling with a down-the-hole hammer and soil displacement. In this method, the spoil is not brought to the surface but is displaced into the subsoil immediately surrounding the borehole by means of compaction [Arnol93] [FI-Vick]. The drilling equipment (Bild 6.2) (Bild 6.2) is similar in design to the rotary-percussive down-the-hole hammer drilling machine that … |
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Because the unmanned, non-steerable techniques (Abschnitt 5) have severe limitations in terms of directional accuracy, international efforts have been underway since the 1970s to develop unmanned steerable techniques for trenchless installation of cables and pipes. The result is that today there are numerous steerable techniques. They represent either a further development of the non-steerable techniques (Abschnitt 5) or new developments based on … |
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