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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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Nov 03, 2004 |
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Feb 16, 2011 Of the main forms of cracks mentioned, the ones that occur most often in rigid piping are longitudinal cracks (Bild 2.8.1.1).
In most cases they occur in the quarter points of the pipe (Bild 2.8.1.1). The crown and invert cracks open on the inside, the side cracks on the outside (Bild 2.8.1.1) |
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Feb 16, 2011 Besides the causes of damage already mentioned above, longitudinal cracks occur specially through [ATVM143-1:1989] :
With rigid piping, longitudinal cracks occur due to exceeding the annular bending strength, e.g. with the lay of the pipe. In addition, cracks can originate as a result of position deviation caused by changes of the bedding … |
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Nov 03, 2004 |
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Lateral cracks mostly encompass the whole circumference of the pipe (Bild 2.8.2.1) (Bild 2.8.2.1).
Predestined places are the middle of the pipe (Bild 2.8.2.1), the pipe joints or connections to manholes or structures or transfer to a direct structure. (Image: Formation of circumferential cracks due to incorrect … |
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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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Nov 03, 2004 |
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Feb 16, 2011 Besides the longitudinal and lateral cracks, which have a fixed course of the crack, there are cracks in sewers that either originate at a point and radiate outwards (Bild 2.8.3.1) or cracks with a completely irregular course (Bild 2.8.3.1) (Bild 2.8.3.1).
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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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Nov 03, 2004 |
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Pipe break is understood to be the missing of more or less large pieces of the pipe walling (Bild 2.8.4.1) (Bild 2.8.4.1) (Bild 2.8.4.1) (Bild 2.8.4.1).
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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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Nov 03, 2004 |
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Collapse is understood to be the complete loss of carrying capacity connected with the destruction of the respective component (Bild 2.8.5.1) (Bild 2.8.5.1) (Bild 2.8.5.1).
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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 |
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Feb 16, 2011 The consequences of damage when cracks occur in sewers are substantially influenced by
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Nov 03, 2004 The "cracks" type of damage occurs primarily in rigid piping, whereby distinction is made between three main forms which can be the precursors for the pipe break and, finally, for the collapse of the sewer [ATVM143-1:1989].
The causes of cracks are closely connected with their type, whereby the form of a crack, its dimension and its course allows … |
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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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