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Congratulations! You have successfully finished this lesson. Next you will have the opportunity to review the newly acquired knowledge with an interactive questionnaire. You can of course still navigate back to any point in the lessons if you wish to review a specific point or subject. Stay curious! |
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The construction of sewers is often carried out using the open construction method. Depending on the design, this results in pipe-soil systems with different external loads on the sewer. To understand these relationships, the soil mechanical and hydrogeological principles for characterizing the subsoil are explained. After completing this module, you will have a sound knowledge of how: - to differentiate between soil types;
- to identify the influences of grain shape and grain size distribution on the practical construction properties of the subsoil and
- to name the different appearances of water in the subsoil;
- to determine the water permeability of the soil for a constructional assessment of the soil.
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The lecture series "Repair of manholes made of concrete, reinforced concrete and masonry" presents several possibilities for repairing manholes. The first part of the series deals with the structure, functions and conditions of manholes. The aim of this lecture is to provide a brief overview of the structure, functions and conditions of manholes as the most frequent construction elements of drains and sewers as well as to familiarize the reader with … |
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DIN EN 752-1 Manhole:
Chamber with a removable cover constructed on a drain or sewer to permit entry by personnel [DINEN752-1]. | DIN EN 1917 Manhole:
Vertical watertight structure used to connect pipelines, to change direction and/or level, to permit access for personnel and/or equipment for inspection and maintenance and to allow aeration and ventilation [DINEN1917:2004]. |
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(Image: Masonry manhole)
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(Image: Manhole of in-situ concrete)
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Manholes were in the past preferably built of masonry , of in-situ concrete or of prefabrications of concrete or reinforced concrete. The state of the technology of current mainly prefabricated manholes or manhole prefabrications of concrete or reinforced concrete is documented in DIN 4034 Part 1 [DIN4034-1:1993]. At a European level, the CEN-N 393E [CENN393], whose area of application … |
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| (Image: Manhole components according to DIN EN 1917 [DINEN1917a] [Image: S&P GmbH]) |
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| (Image: Structure of a manhole)
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(Image: Underfilling the frame of the manhole top with mastic asphalt)
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(Image: Vertically adjustable manhole top with spring element)
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(Image: Cross section of a manhole top when embedded into the carrier layer and paved with specifically shaped stones with reference to [FI-Schwab] [Image: S&P GmbH])
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(Image: View into the cleaned starting manhole)
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(Image: View into the opened manhole)
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(Image: Climbing … |
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(Image: Jointing of shaft rings with cement mortar (above the ground water ) with reference to [ATVA241a] [Image: S&P GmbH])
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(Image: Jointing of shaft rings with plastic gasket (in the ground water ) with reference to [ATVA241a] [Image: S&P GmbH])
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Connections of concrete shaft rings were exclusively made of cement mortar for decades . Since the introduction of plastic sealing media and elastomer gaskets these were, and are, used in the application . |
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According to ATV-DVWK-A 157 [ATVA157], sealing media are currently required to be made exclusively of elastomers following DIN EN 681 [DINEN681:2003] and DIN 4060 [DIN4060:1998] to seal the joints between the prefabricated manhole components. |
(Image: Shaft ring sealings of elastomers with reference to [FI-Denso] [Image: S&P GmbH] – sealing ring with dense structure for spigot ends according to DIN 4034-1)
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(Image: Shaft ring sealings of elastomers … |
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According to DIN EN 1917 [DINEN1917:2004], other sealing media are also allowed but they must meet the tightness requirements of the material. | (Image: Component joints according to DIN EN 1917 [DINEN1917a] – elastomeric sealing)
| | (Image: Component joints according to DIN EN 1917 [DINEN1917a] – elastomeric, plastomeric or other sealing media)
| (Image: Component joints according to DIN EN 1917 [DINEN1917a] – elastomeric, plastomeric or other sealing … |
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Functions - access
- ventilation
- connection of pipelines (discharge or transmission of sewage)
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Requirements - leak-tight
- load-bearing
- safe for traffic
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(Image: Functions of manholes - Accessibility of manholes)
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(Image: Functions of manholes - Natural ventilation)
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(Image: Functions of manholes - Discharge and transmission of sewage)
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(Image: Requirements on manholes - Leak-tight - Stressing of manhole by external water pressure e.g. with in-situ groundwater)
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| (Image: Functions of manholes - Accessibility of manholes)
| (Image: Defective (1) or missing (2) step irons)
| | (Image: Height difference Δh between ground level and step)
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| (Image: Functions of manholes - Natural ventilation)
| (Image: Technical ventilation method with reference to [FI-BSBel] - overpressure ventilation with high-power fan and ventilation shroud [Image: S&P GmbH])
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| (Image: Functions of manholes - Discharge and transmission of sewage)
| (Image: Sewage exiting a manhole as a result of flooding (City Drainage Zurich))
| | (Image: Stagnant sewage in a manhole)
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(Image: Requirements on manholes - Leak-tight - Stressing of manhole by external water pressure e.g. with in-situ groundwater)
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(Image: Infiltrating groundwater)
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| (Image: Stressing of manhole by internal water pressure e.g. in connection with leaktightness testing and in-situ groundwater)
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| (Image: Requirements on manholes - Load-bearing)
| (Image: Cracks in a brickwork manhole)
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| (Image: Requirements on manholes - Safe for traffic)
| (Image: Manhole top raised above street level as a result of settling)
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Clanging manhole covers may not only be obstacles to traffic but are often considered as noise disturbance. |
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Standards and regulations |
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| (Image: Leakage testing of manholes with water as the test medium - test criteria to EN 1610 / ATV-A 139) |
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Damages of manholes made of concrete, reinforced concrete and masonry according to DIN EN 13508 - crack formation
- break/collapse
- defective brickwork or masonry
- missing mortar
- surface damage
- displaced joint
- intruding connection
- defective connection
- intruding sealing material
- obstruction caused by lining defect
- defective repair
- porous pipe wall
- soil visible through defect
- void visible through defect
- defective step or ladder
- defective cover or frame
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| (Image: Damages of manholes made of concrete, reinforced concrete and brickwork)
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(Image: Infiltrating groundwater)
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(Image: Manhole top below the street level as a result of settling of the manhole or failure of the mortar gaps between the manhole top and the manhole taper)
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(Image: Defective (1) or missing (2) step irons)
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(Image: Manhole - Displacement)
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(Image: Defective step in a masonry manhole)
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(Image: Biogenic sulphuric acid corrosion … |
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