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(Image: Disposing the solids-drilling-fluids mixture as fertilisar on agricultural land [FI-Tracta]) The pumping out and transporting of unusable drilling fluid and cheap disposal into the sewer system, to waste dumps or agricultural land (Bild 10.9.1) was often used in the past. The growing environmental awareness of the public and especially the discussions in the year 1999 about the environmental friendliness of bentonite within the framework of … |
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(Image: Separation of the spoil by sequentially arranged settling basins) The simplest and most economic method for separating solids from the fluid phase is the use of settling technology. In this method, the drilling fluid, enriched with the spoil, is fed into excavations serving as settling basins or into transportable tanks (e.g. steel containers) where the solids can settle out (Bild 10.9.2). The cleaned fluid is then pumped off at the top or … |
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In the first separation step (coarse separation), … |
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In the second separation step (medium separation), the sieve particle proportion (2 to 6 mm) of the suspension of the first step is further cleaned by means of hydrocyclones. In principle, a hydrocyclone (Bild 10.9.3.2) is a fully jacketed centrifuge of slim form in which the pipe does not move. The cloudy suspension is fed tangentially under pressure through jets into the coned container and there forced … |
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In the third separation step, the fines are separated out of the cloudy suspension, e.g. from the clay in the particle size region < 0.002 mm. As the particle size distribution of the fines overlaps that of the bentonite, the separated remainders may also possess substantial remainders of bentonite [Arnol93] [FI-AKW] [Schri01]. The spectrum of the technology used in this separation step ranges from centrifuges to filter presses. The method of operation … |
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The basic design of separation plants and the dimensions of the individual separation steps are determined mostly by the in-situ subsoil, the specific limiting conditions at the construction site, the diameter of the pipeline to be installed and the economic intentions as regards the quantities to be handled (Tabelle 10.9.3.4). (Video: Flow scheme of a three-stage hydrocyclone separation plant) (Table: Influence of construction and geological limiting … |
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Important aspects that also determine the cost effectiveness of a hydraulic conveying installation are the type and scope of the separation that is required and the preparation of the pumped solids-drilling-fluid mixture. The purpose of separation is the removal of the solid components from the drilling fluid, on the one hand, to return the drilling fluid again to the conveying circuit and, on the other hand, to make the separated solids (spoil) fit … |
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In order to achieve a change of direction of the boring or displacement head (… |
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The measurement instruments utilized for determining position and direction can be divided as follows:
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Jul 06, 2007 Trenchless Technology for Installation of Cables and Pipelines Optical measurement instruments (vertical and horizontal deviation) (Image: Principle and structure of the theodolite [Kahme97]) The theodolite is an instrument for measuring horizontal and vertical angles (Bild 11.2.2.1). Its main components are the upper body rotating about the vertical axis, with the vertical graduated dial, the telescope rotating horizontally on a hinge pin, the lower body with the horizontal graduated dial as well as arrangements for reading the graduation divisions for levelling (equal to vertical … |
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Jul 06, 2007 Trenchless Technology for Installation of Cables and Pipelines Optical measurement instruments (vertical and horizontal deviation) Laser beams are visible, mono-coloured, strongly bundled and coherent light rays. Coherence means that the individual light waves vibrate in a fixed phase relationship in common mode. Laser is an acronym for "Light amplification by simulated emission of radiation" and this term is meanwhile used for the whole appliance that generates the laser beam. The invention of the laser (Maiman 1960 [Maima00]) soon led to it being used in measurement technology … |
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Jul 06, 2007 Trenchless Technology for Installation of Cables and Pipelines Optical measurement instruments (vertical and horizontal deviation) (Image: Laser theodolite (PENTAX ETH-120 F) [FI-tacs] [FI-GeoFe]) The coupling of a directional laser with a theodolite results in the laser theodolite (Bild 11.2.2.3) [Colli84]. In this case the laser beam replaces the optical beam. It is beamed through the telescope and projects the light point on the target board. The laser theodolite can provide directions in space. Also, by rotating the theodolite about the vertical axis, the generation of horizontal … |
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"A gyroscope can be generally designated as a rigid body that carries out a desired rotational movement. Fundamental features are its steady state capacity (inertia) and its precession (advertence due to external moments acting on its axis of rotation). With respect to its ability to move in all three axes, about two axes or about a single axis, one differentiates gyroscopes with three or two degrees of freedom or a single degree of freedom" [Deuml80]. |
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One apparatus for hydrostatic height measurement is the hose water level. The principle of measurement is based on the physical property of fluids in connected containers of any cross section always to find the same level (communicating pipes). In the simplest case, one end of the hose is situated at the point of measurement (possibly in a sensor which, for instance, can be moved by a pipe) and, at the other end of the hose, the changes of height of … |
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Of further importance for the steering of a microtunnelling or shield machine is the knowledge of its inclination and roll angles (Abschnitt 11.2). For the determination of inclination and roll angles of the microtunnelling … |
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The measurement of the distance travelled by the jacking or shield machine or by the boring and displacement head (jacking advance) is of primary importance for determining position. This can be carried out by means of:
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With this measurement system a passively illuminated (Bild 11.3.1.1) or self-illuminated target board (diode target board) is observed by the person carrying out the measurement or the equipment driver at predetermined jacking stations through the telescope in order to read off the target board coordinates (Bild 11.3.1.1).
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This measurement system corresponds in principle to the one with theodolite or laser theodolite with direct target board observation (Abschnitt 11.3.1.1). In this case, the picture of the target board is not seen directly by an observer but is recorded by a video camera that can be installed either in the target board itself (Bild 11.2.2.2) (Bild 11.3.1.2), near the target board (Bild 11.2.2.2) or in the ocular of the theodolite (Bild 11.3.1.2) and … |
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The combination of directional laser with active target board has found wide acceptance especially with microtunnelling and pipe jacking for a selection of manual, semi- or fully automatic steering methods [Fitzk94]. In this case, a laser beam that impinges on an active target board is used as an optical means of guidance (Abschnitt 11.2.2.2). One representative of this standard measurement system is the ELS (Electronic Laser System) (Tabelle 11.3.1.3) |
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