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For a bedding “Type 2” there is no lower bedding layer. The pipes are directly laid on the accurately pre-profiled (pre-formed) trench bottom, thus reducing the thickness of the upper bedding layer at the same time. For that purpose it is required that the natural (in situ) soil is relatively fine and can be compacted well. (Image: Bedding “Type 2” DIN EN 1610) (Image: Bedding “Type 2”) (Image: Example bedding type 2 for a GRP pipe - Attention: Minimum … |
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The bedding “Type 3” is also only applicable in especially suitable soils. This method does not have a lower bedding layer or a pre-formed trench bottom. The pipes are laid directly on the trench bottom, hence increasing the risk of point load damage especially for pipes without a base. (Image: Bedding type 3 according to EN 1610) (Image: Schematic representation of the type 3 bedding) |
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When is a concrete bedding useful? Concrete bedding (concrete support) is a “special type of bedding construction” which is used in the following circumstances:
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The placement of pipes in concrete bedding includes:
(Image: Installation of a reinforced concrete … |
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In the case of concrete pipes with an integrated base, the base takes over the function of the upper bedding layer. Therefore, they can usually be placed directly on a prepared, horizontally levelled and compacted bedding of suitable soil material (lower bedding layer), directly on the prepared trench base or on a concrete support. Even with these type of pipes, it is necessary to compact the haunch areas by hand to ensure proper compaction. For placement … |
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(Image: Installation of a reinforced concrete pipe on a concrete base in accordance with) After the placement of the lower bedding (concrete slab), the pipe is first placed on wedges and then the upper bedding layer is cast. This "concreting in two phases" is practiced in order to ensure a uniform embedment. Direct “placement" of the pipe on a concrete slab followed by concreting of the pipe haunch can lead to a linear bearing! Important: The wedges … |
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In the structural calculation of the pipe, the pipe bedding is defined by the "placement method" and the "bedding angle" [ATVA127].
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The bedding type is determined as part of the planning process. The default bedding should be type 1. (Table: Bedding and Placement type allocation as per DIN EN 1610 and ATV-DVWK-A 127) |
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For pipes without the integrated base, the bedding angle (2α) is usually set between 90 ° and 180 °. For pipes with the integrated base, the bedding angle is normally 60 °. (Image: Variable support angle (2α) in pipe without a base) (Image: Variable support angle in pipe with a base) |
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(Image: Influence of the support angle on the pipe stress) What is the impact of a decreasing bedding angle? Influence of the bedding angle on the pipe stress.
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Incorrect:
Result: load concentration Correct:
Result: good load distribution (Image: Load concentration due to an unfavorable compaction ratio between the trench base and subbase) (Image: Good load distribution as a result of a favourable compaction ratio between the trench base and subbase) |
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(Image: Effects of uneven longitudinal load distribution) What kind of impact have highly compacted bedding areas? Highly compacted areas within the bedding layer lead to the formation of point loads (shown dotted thickly here) resulting in the cracking of the pipe. |
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Congratulations! You have successfully finished this module. 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 modules if you wish to review a specific subject. Stay curious! |
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Aug 22, 2016 The embedment consists of bedding, side filling and initial and main cover. The quality of the embedment is significantly influenced by the installation conditions of the pipes. Other topics of this module include flowable fill for trench backfill, optimized installation methods and compaction tests. After completing this module, you will have a sound knowledge of:
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Mar 08, 2017 AE-02 Open Cut Method: Occupational Health and Safety Occupational Health and Safety Administration Requirements in the USA The Occupational Safety and Health Administration's (OSHA) Standard Title 29 of the Code of Federal Regulation (CFR) contains the requirements for safety and health for construction [[OSHA Standard- 29 CFR, Part 1926]]. Many OSHA documents use the term "competent person" as "one who is capable of identifying existing and predictable hazards in the surroundings or working conditions which are unsanitary, hazardous, or dangerous to employees, and who … |
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Mar 16, 2017 AE-02 Open Cut Method: Occupational Health and Safety Occupational Health and Safety Administration Requirements in the USA Part 1926 of the OSHA Standard- 29 CFR is the Safety and Health Regulations for Construction part. The table below encompasses the table of contents of the part. The student is referred to the OSHA website for further reading. (Table: OSHA Standard 29 CFR Part 1926) |
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Mar 15, 2017 AE-02 Open Cut Method: Occupational Health and Safety Occupational Health and Safety Administration Requirements in the USA [[OSHA Standard- 29 CFR, Part 1926]] requires that all excavations in which employees could potentially be exposed to cave-ins be protected by:
The OSHA standard suggests three methods for designing protective systems for preventing potential cave-ins. The table below summarizes these … |
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Mar 15, 2017 AE-02 Open Cut Method: Occupational Health and Safety Occupational Health and Safety Administration Requirements in the USA (Image: Attention!) Ladders, steps, ramps, or other safe means of exit for employees working in trench excavations deeper than 4 ft (1.22 m) must be provided. These devices must be located in the excavation within 25 ft (7.62 m) of all workers. Any structural ramps used must be designed by a competent person if they are used for employee access or egress, or by a competent person qualified in structural design if they are used for vehicles. Also, structural … |
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Mar 15, 2017 AE-02 Open Cut Method: Occupational Health and Safety Occupational Health and Safety Administration Requirements in the USA The student must understand that it is impossible to cover every requirement of the [[OSHA Standard- 29 CFR, Part 1926]] Manual in this short course as it relates to trench and excavation safety. Therefore, the student is encouraged to access the official OSHA webpage to learn more about this topic: https://osha.gov. |
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Mar 15, 2017 AE-02 Open Cut Method: Occupational Health and Safety Occupational Health and Safety Administration Requirements in the USA (Image: Attention!) Similarly, it would be extremly long and cumbersome to present all requirements about the installation, maintenance and application of traffic control devices on all public streets, highways, bikeways and private roads open to public travel. The student is referred to [[Part VI of the Manual on Uniform Traffic Control Devices (MUTCD)]] for a very detailed overview of the following pages. |
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Mar 15, 2017 AE-02 Open Cut Method: Occupational Health and Safety Occupational Health and Safety Administration Requirements in the USA Barricades serve various functions on the construction site, including:
According to [[Part VI of the Manual on Uniform Traffic Control Devices (MUTCD)]] "Stripes on barricade rails shall be alternating orange and white retroreflective stripes (sloping downward at an angle of 45 degrees in the direction traffic … |
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Mar 15, 2017 AE-02 Open Cut Method: Occupational Health and Safety Occupational Health and Safety Administration Requirements in the USA (Image: Attention!) Traffic cones are used to channelize traffic, divide opposing traffic lanes, divide traffic lanes when two or more lanes are kept open in the same direction, and delineate short-duration maintenance and utility work. Cones can be doubled up to increase their weight. Some cones are constructed with bases that can be filled with ballast [[Part VI of the Manual on Uniform Traffic Control Devices (MUTCD)]]. |
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Mar 08, 2017 AE-02 Open Cut Method: Occupational Health and Safety Occupational Health and Safety Administration Requirements in the USA Vertical panels shall be 8 to 12 in wide and at least 24 in high. They shall have orange (fluorescent red-orange or fluorescent yellow-orange) and white stripes, and be retroreflectorive. Panel stripe widths shall be 6 in, except where panel heights are less than 36 in, when 4-in stripes may be used. If used for two-way traffic, back-to-back panels shall be used. Vertical panels may be used to channel traffic, divide opposing lanes of traffic, divide … |
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