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Feb 16, 2011
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Feb 16, 2011
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Nov 03, 2004 The main cause of leaks is the result of construction work that is not carried out in accordance with the recognised rules of the technology. Thus, in many cases for instance, the sewers often had to undertake the additional duties of a land drainage pipe. Among others, this was achieved by using pipes with half sockets (Bild 2.2.2.1.3) (Bild 2.2.2.1.3) (Bild 2.2.2.1.3) in which the gasket in the region of the crown was also purposely dispensed with. |
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Feb 16, 2011 During operation, unplanned stresses can be applied to the pipe joints or components from the outside as well as from the inside and these can lead to damage with leaks, e.g.
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Nov 03, 2004 The selection of materials and components were, and are, strongly characterised by their respective stresses as well as by the current state of the technology. Thus, one can assume, for instance, that the sealing materials used earlier (Abschnitt 1.7.1) such as clay, cement mortar, poured asphalt and cold-worked sealers (Bild 2.2.2.1) (Bild 2.2.2.1) no longer meet today's requirements and, if not already replaced, contribute, in a not unsubstantial … |
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Feb 16, 2011 In professional circles the theory was long maintained that seepage of the sewage could not occur because leaks block or seal themselves due to the solids in the sewage [Stein88g]. Another theory is that the exfiltration of sewage from leaking sewers is a desirable and environmentally friendly component of wastewater disposal. The reasoning behind this points to the earlier usual targeted seepage of a portion of the communal sewage and the almost … |
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Feb 16, 2011 If leaking gravity flow sewers or structures of drain and sewer systems are constantly or occasionally in the groundwater (Bild 2.2.3.1), then groundwater infiltration will occur (Bild 2.2.1) (Bild 2.2.1) whereby, at the same time, soil material from the embedment can be flushed in. Infiltrating water belongs to the category of extraneous water and is thus an unwanted portion of the wastewater to be discharged [ATV82] [Graf84] [Klass85] [Liers85]. |
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According to [ATVM143-1:1989], the following are the causes of damage from flow obstacles:
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Feb 16, 2011 (Image: Possible positional deviations of manholes) Possible causes of positional deviations can be [ATVM143-1:1989]
Further causes for settling differences between manholes and pipes are, for instance, [ATV82] (Bild 2.4.2) :
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Nov 03, 2004 According to [ATVM143-1:1989], the cause of external corrosion of sewers of cement-bound materials can be due to the following:
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In order to estimate the rate of corrosion in cement-bound pipes as a result of biogenic sulphuric acid corrosion, there are in existence various values based on experience and models, which partly however, provide very different results [Lohse95] :
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Nov 03, 2004 According to [ATVM143-1:1989], internal corrosion can have the following causes:
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Deformations in the sense of damage can be caused by [ATVM143-1:1989] :
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For the evaluation of the cross sectional figures measured at individual measuring stations in the sewer, Bosseler [Bosse97] suggests a circular ring with a negligible wall thickness t as an un-deformed starting system. In the level, every point P on the circumference possesses two degrees of freedom, which are described by the tangential displacement v (in a positive clockwise direction) and the radial displacement w (positively directed towards … |
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With knowledge of the approximated bending lines, there arise, on the basis of the coefficient or the Fourier row approximation, also possibilities for interpretation for the internal pliability Wi of the deformed linear elastic circular ring. With the use of the row statement (Formel 2.7.4), this can be calculated in accordance with [Bosse97] to: (Formula: Pliability with the use of the row statement to Bosseler) It becomes clear from Formel 2.7.5… |
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Besides the analysis of individual measured cross sections, an evaluation of the sequence of the individual amplitudes and phase angles over the length of the section of the sewer is also of interest. For this purpose, the parameters can be plotted with reference … |
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Thin walled piping fails under bending due to buckling [Seide61] [Axelr83b], as has also been confirmed by experiments [Spenc79] [Brazi27]. A theoretical introduction and bibliography is given in [Axelr80]. In the condition of buckling deformation, there occurs a deformation of the pipe cross section (ovalisation) that must not be ignored in connection with the elastic kinking. This non-linear bending of pipes - the so-called Brazier problem [Brazi27] - … |
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As already mentioned in Abschnitt 2.7.1, only very superficial suggestions for classifying deformations exist at present, and these are limited to the characteristic σv of the vertical deformation which evaluate larger ones than the generally measured deformations as damage (e.g. [ATVA149]). In Abschnitt 2.7.4 there was detailed the possible forms of the incorrect estimations connected with them, which can, however, be prevented with the geometric … |
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Lateral cracks originate due to exceeding the permissible longitudinal bending strength, the tensional strength in the longitudinal direction or the shear strength of the pipe. Besides the causes mentioned above, lateral cracks can occur especially due to [ATVM143-1:1989] :
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Feb 16, 2011 The most important causes of damage for cracks originating at a point which can lead to pipe fracture, besides those mentioned above, are:
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A pipe break is caused by an additional malfunction or changed internal or external loading of an already damaged pipe having a crack or being fractured. Furthermore, according to [ATVM143-1:1989], it occurs due to leaks, mechanical wear, corrosion and cracks. |
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A collapse is the final phase, and the one with the most serious consequences, in the development of the following damage over a period of time.
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Nov 03, 2004 As the above paragraphs have shown, numerous cases of damage from various causes can occur in sewer systems as well as in structures of drain and sewer systems. Here it must be taken into account that the consequence of damage is determined mostly by its extent, the respective materials of the pipe and the local limiting conditions. A comprehensive overview of the main groupings of damage and their causes and consequences is given in Tabelle 2.9. (… |
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According to EN 752-5 [DINEN752-5:1997], after rehabilitation, the nominal condition of a structure, a sewer sector, a section of the sewer, a network region or drain and sewer system must conform at least to the same standards that apply to a new sewer. Naturally, this also applies to the materials and components used [Rothe83]. The loading that is possible and the corresponding characteristics required are given in very general form in Tabelle 5.1 |
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Jul 24, 2014 Article Dragisa Dubocanin The use of polyethylene pressure pipelines is gaining ever greater international regard and becoming ever more sophisticated.The reasons are diverse, and include this material‘s excellent resistance to corrosion, the flexibility of PE 100 pipes, and the resultant installation and cost benefits.
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