In selected pipe joints inductive position sensors are installed to supervise the joint gaps. At least three sensors are mounted and calibrated in each measurement joint. As a general rule, two or three measurement joints are aligned one after another. The inductive position sensors project to the interior of the pipe radially about 8 cm and have a length of about 35 cm. An additionally required box with the side lengths of 32 cm x 32 cm projects … |
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The jacking resistances consist of:
(Image: Penetration resistance and jacking force) |
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Skin friction is determined by:
The skin friction, which is decisive for a dimensioning of the main jacking station and the jacking pipes, can basically be influenced by an overcut and by filling the overcut with lubricant and support medium. (Image: T.B.K. system [FI-TBKa] - Injection medium (Polymer drilling fluid consisting of polymer and water)) (Image: Annular … |
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May 04, 2020
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Curved jackings and steering errors frequently induce additional, radially directed guiding forces between the pipe and the subsoil. These forces increase the frictional resistance. Since this resistance is dependent on the longitudinal force in the pipe string, it increases in the course of the jacking. The effect of repeated steering errors is particularly disadvantageous, because the single resistances do not sum up, but lead to disproportionate … |
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Thus, besides the creation of an overcut and the lubrication and support of the associated annular gap from DN/ID 800 (32 in), intermediate jacking stations can be installed from DN/ID 500 (20 in) for sectional or cyclical jacking of the whole pipe string in order to reduce the jacking force. New developments in past years have aimed at, among other targets, reducing the individual forces connected with jacking still further and making them more calculable. … |
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Modern alignment of jacking spans poses constantly increasing requirements for jacking pipes. Looking back to recent years, it is apparent that jacking lengths are getting longer and longer while narrow curves are becoming more and more frequent. Even complicated curve combinations, partly with multiple S- or three-dimensional curves, are no longer a rare sight in calls for tenders. Conventional pipe joints with pressure transfer rings made of wood … |
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The concept is described below for the CoJackHydra system. In CoJackHydra, the CoJack calculation and control system is combined with a new pressure transfer system (hydraulic joint) consisting of a water-filled high-pressure hose. The "Hydraulic Joint" replaces the pressure transfer ring between the jacking pipes, which usually consists of a chipboard or oriented strand board (OSB). Among other things, the system allows a better angular deflection … |
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The amount of water in the hose is dimensioned depending on the project in such a way that the maximum possible jacking force is achieved while ensuring the necessary deviation ability. CoJackHydra allows for significantly higher jacking forces than conventional pressure transfer rings, especially in tight curves or in curve combinations (S-curves) in the jacking alignment. Visual description of the steering procedure:
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1. Higher permissible jacking forces particularly in curves
2. Better angular deflection of the pipe joints
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The hydraulic joint is supplied as single or multiple circumferential closed rings. The position is fixed without drilling or gluing to the pipe end. There must be no recesses or bevels on the inside of the jacking pipe or on the concrete edges of the pipe end. Any recesses on the pipe end faces must not extend to the inner or outer surface of the pipe. This also applies to the concrete on the steel collar to avoid leakages. The pocket for receiving … |
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Mar 17, 2006 Renovation: Lining with Continuous Pipes - Part III - Method Variants with Annular Space
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Mar 17, 2006 Renovation: Lining with Continuous Pipes - Part III - Method Variants with Annular Space
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Mar 17, 2006 Renovation: Lining with Continuous Pipes - Part III - Method Variants with Annular Space
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Mar 17, 2006 Renovation: Lining with Continuous Pipes - Part III - Method Variants with Annular Space
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The earth structural stability analysis includes:
The first two assessments that only apply to the shafts reaching … |
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Aug 05, 2008
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Jan 25, 2005 The jacking resistances consist of:
(Image: Penetration resistance and jacking force) |
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Aug 05, 2008 Skin friction is determined by:
The skin friction, which is decisive for a dimensioning of the main jacking station and the jacking pipes, can basically be influenced by an overcut and by filling the overcut with lubricant and support medium. (Image: T.B.K. system [FI-TBKa] - Injection medium (Polymer drilling fluid consisting of polymer and water)) (Image: Annular … |