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Aug 03, 2005 (e.g. methods AVP [FI-Herreb], MTB-P [FI-Hazem]) (Image: Microtunnelling with pneumatic spoil removal) Method of operation and sequence Microtunnelling with pneumatic spoil removal on the basis of a suction plant is characterized by the jacking of pipes with simultaneous full-surface excavation by a cutting head of the mechanically or earth-pressure balanced working face as well as by the continuous conveying of spoil out of the excavation chamber inside … |
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Aug 03, 2005 The unmanned, steerable microtunnelling techniques employed base generally on the principle of soil removal. Depending on the way of conveying the spoil, it is differentiated between:
In all cases the different soil- and rock types are taken into account by the different … |
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Aug 03, 2005
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Aug 03, 2005 On the German market more or less standardized jacking pipes, which are made of various materials and which are also employed in the open-cut method of construction and also have different nominal sizes, are offered for the application case at hand and for the methods dealt with here by observing ATV-A 125E [ATVA125:1996], EN 12889 [DINEN12889:2000], EN 14457 [DINEN14457:2004] and the corresponding product standards (Bild 4.1) (Bild 4.1) (Bild 4.1) |
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Aug 03, 2005 The connections of jacking pipes, called pipe joints or joints in the following, must ensure that the following criteria are met:
Examples of suitable pipe joints in the form of flexible, non-restrained socket and spigot joints according to EN 14457 [DINEN14457:… |
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Aug 03, 2005 Jacking pipes are to be delivered packed and are to be stored on the construction site in such way that they are secured against rolling and sliding also in the case of individual withdrawal [ATVA125:1996] [BGI780]. Excessive stacking heights should be avoided so that pipes in the lower part of the stacks are not overloaded. Stacks of pipes shall not be placed close to open trenches or shafts. Pipes with protective coatings shall not be stored where … |
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Jun 01, 2004
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Aug 03, 2005 In the following, jacking pipes will be understood to be prefabricated pipes with the following characteristics: pipes with non-restrained, flexible joints within the wall thickness; pipes have smooth even external contours; these pipes are pressed-in or pushed-in into the subsoil or cavity [Stein05a]. |
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Aug 03, 2005 The results of the geotechnical investigation as well as the laboratory analyses must be determined accurately by the geotechnical specialist or engineering geologist and described in a geotechnical report. According to DIN 4020 [DIN4020:2003] [DIN4020:2003], the geotechnical report comprises the presentation and evaluation of the results of all geotechnical investigations and the conclusions to be drawn with regard to the project and the construction … |
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Jun 01, 2004 (Image: Diagram of soil and rock classification in accordance with DIN 18319 [DIN18319]) The soil and rock classes, for trenchless technology for installation of prefabricated pipes of any profile by means of pressing-in, pushing-in, ramming-in or pulling-in, is defined in the Federal Republic of Germany by DIN 18319 " Contract procedures for building works - Part C: General technical specifications for building works; Pipe drilling works " [DIN18319:… |
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Aug 03, 2005 When using the trenchless method of construction a sufficient and carefully carried out geotechnical investigation is decisive for the technical and economic success of a trenchlessly carried out sewer construction measure since the geotechnical and hydrogeological subsoil conditions decisively determine the selection of the jacking technique (machine type, conveying system, cutting head variant). In the sense of DIN 4020 [DIN4020:2003] [DIN4020:2003], … |
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Aug 03, 2005 Shafts are usually always necessary for trenchless installation of pipelines with the methods of microtunnelling and pilot pipe jacking. The term shaft is understood to be a depression in the ground surface that is created by sinking (excavation or vertical boring), with suitable support, that serves for the underground creation of bore holes with the aid of the methods of trenchless installation and for the transport of humans, machines, substances (… |
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Aug 03, 2005
The location and the number of shafts are decisively influenced by the lay out of the sewer and the requirements of the trenchless construction method (e.g. realisable jacking length (Abschnitt 4.4), straight … |
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Jun 01, 2004
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Aug 04, 2005 The most widely used method in Germany for securing rectangular shafts, or shafts deviating from the circular, is that of using sheet planks or sheet piles because the construction companies have extensive experience in handling this type of lining and usually also possess the equipment required for it. The steel sheet planks or sheet piles with wall thicknesses between 3 mm and 8 mm are driven into the soil by means of ramming, vibration (shaking) … |
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Jun 01, 2004 According to EN 13331-1 [DINEN13331-1a] [DINEN13331-2], trench lining system is understood to be a construction of prefabricated components that are used for support of vertical excavation walls. The main load-bearing elements are panels, slide rails and support components. In the application case at hand, the following trench lining systems are used in the open cut method of construction [DINEN13331] :
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Jun 01, 2004 An open sinking shaft is a shaft open at the bottom that is usually constructed in sections of in-cast concrete or of prefabricated reinforced concrete elements (Bild 6.4.3) (Bild 6.4.3) (Bild 6.4.3) on a manufacturing platform and that is sunk to its foundation level with simultaneous excavation of the core (Bild 3) (Bild 3) (Bild 3).
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Aug 03, 2005 (Image: Methods for securing shafts [Stein05a]) Decisive for the selection of a method of shaft construction, i.e. the measures for sinking and securing of a shaft, can be, for example [Stein05a] :
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Aug 04, 2005 When opening up the exit and entrance openings with jacking in soil that is free of groundwater, the main task is to avoid ground failure. In the cases in which a bentonite suspension is injected into the annular gap for reducing skin friction, or in which, despite the absence of groundwater, closed shields with fluid support or earth pressure support of the working face are used, care must be taken regarding sealing measures like in saturated subsoils (… |
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Jun 01, 2004 The gasketed opening seal consists of a single or double or duplex elastomeric seal (for high groundwater pressures) (Bild 6.5.2.1) (Bild 6.5.2.1) (Bild 6.5.2.1) (Bild 6.5.2.1) that is attached between the shaft wall and a correspondingly seal fixture. The seal fixture may use a steel fixed flange, an exit or entrance top hat or similar and, if necessary, additional intermediate rings as well as a bolted loose flange often consisting of several segments. … |
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Aug 04, 2005 Their purpose is to provide a transition, without damage, from the atmospheric pressure in the shaft to the groundwater pressure outside in the subsoil in order to permit unhindered exit and entry of the microtunnelling machine at the time of the opening of the shaft lining without additional measures. Pressure chambers always possess two locks and an integrated gasketed opening seal (Abschnitt 6.5.2.1) into which the microtunnelling machine enters. |
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Aug 04, 2005 (Image: Dewatering properties of different types of soils with water retention measures [Herth95]) The following measures are possible in order to prevent ground failure and groundwater inflows when creating and traversing the exit and entry openings [Stein05a] :
The simplest solutions, when technically possible are water retention measures for lowering the groundwater level [Rappe96] [DIN18305]. |
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Aug 04, 2005 Within the scope of microtunnelling and pilot pipe jacking a difference is made between the following phases of jacking [Konra01] :
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Jun 01, 2004 Shafts for drains and sewers consisting of jacking pipes have to correspond to EN 476 [DINEN476:1997] and ATVDVWK A 157E [ATVA157], respectively to the materialrelating shaft standards based on them (e.g. EN 1917 [DINEN1917:2004] and DIN V 4034-1 [Konra01] for shafts of precast concrete- and reinforced concrete elements). A manhole (DN/ID 1000) is usually built into the starting- or target shaft (double shell construction method, respectively shaft-… |
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Aug 03, 2005 |
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