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Aug 22, 2016 AE-02 Open Cut Method: Embedment Zone and Pipe Installation Minimum Trench Width Calculation in the US for Various Pipe Materials The following formula can be used as a general guide to compute the minimum trench width for circular concrete pipe installation using the open cut method. (Image: Reinforced concrete pipe) (Table: Minimum trench width for circular concrete pipe in the US) Sample calculation: O.D. = 24” ID + 3 in wall thickness x 2 = 30 in Total trench width = O.D. + (O.D./6 x2) = 30 in+ (30/6 x 2) = 30 in + 10 in = 40 in min |
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Jan 04, 2017 AE-02 Open Cut Method: Embedment Zone and Pipe Installation Minimum Trench Width Calculation in the US for Various Pipe Materials The table below presents the method to select the minimum trench width for HDPE pipe installation using the open cut method for stable ground conditions [[Plastic Pipe Institute]] (Image: HDPE pipe) (Table: Minimum trench width for HDPE pipe in stable ground) AASHTO Section 30 requires a minimum trench width of not less than: Wmin = 1.5 x OD + 12 in (300 mm) ASTM D 2321 requires a minimum trench width of the greater of either the pipe OD + 16 in (400 … |
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Jan 04, 2017 AE-02 Open Cut Method: Embedment Zone and Pipe Installation Minimum Trench Width Calculation in the US for Various Pipe Materials The table below presents the method to compute the minimum trench width for polyvinyl chloride (PVC) pipe installation using the open cut method. (Image: PVC pipe) (Table: Minimum trench width for PVC pipe in the US) |
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Jan 09, 2017 AE-02 Open Cut Method: Embedment Zone and Pipe Installation Minimum Trench Width Calculation in the US for Various Pipe Materials The table below presents the minimum trench width as a function of pipe outside diameter for glassfiber reinforced pipe (GRP) installation using the open cut method. (Image: Glass fibre reinforced plastic pipe (GRP pipe)) (Table: Minimum trench width for GRP pipe in the US) |
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Jan 04, 2017 AE-02 Open Cut Method: Embedment Zone and Pipe Installation Minimum Trench Width Calculation in the US for Various Pipe Materials The table below presents the minimum trench width as a function of pipe outside diameter for centrifugally cast glass-fiber reinforced polymer mortar (CCFRPM) pipe installation using the open cut method. (Image: Centrifugally cast fiberglass-reinforced, polymer mortar (CCFRPM) pipe) (Table: Minimum trench width for CCFRPM pipe in the US) |
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Jan 04, 2017 AE-02 Open Cut Method: Embedment Zone and Pipe Installation Minimum Trench Width Calculation in the US for Various Pipe Materials The table below presents the minimum trench width as a function of pipe outside diameter for ductile iron pipe installation using the open cut method. (Image: Ductile iron pipe) (Table: Minimum trench width for ductile iron pipe in the US) |
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Jan 04, 2017 AE-02 Open Cut Method: Embedment Zone and Pipe Installation Minimum Trench Width Calculation in the US for Various Pipe Materials (Image: Vitrified clay pipe) Trenches for Vitrified Clay Pipe (VCP) installation shall be excavated to a width that will provide adequate working space, but not more than the maximum design width, according to [[ASTM C12-07]]. There is no single formula that is applicable for minimum trench width calculation for VCP. Trench width is mainly one factor to compute loads caused by backfilling to determine the supporting strength of VCP. The factors taken … |
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(Image: Pipe haunches for pipes with circular outer contour) Adequate compaction of the haunch area is decisive to achieve a long service life of the sewer pipe. Because of that, European Standards aim to ensure a working space for all pipes and types of installation, which allows sufficient compaction of the haunch and side fill. Therefore the calculation of the minimum trench width is independent of pipe material and installation type and just a … |
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What are the consequences of non-compliance? If the trench width is too narrow, proper compaction of the backfill material (bedding/pipe support) at the pipe haunch zone cannot be achieved. (Image: Pipe haunches for pipes with circular outer contour) (Image: Inadequate working space at the side of the pipe (no arrow)) (Image: Non-compliance with the minimum trench width - Compaction of the haunch zone and side fill not possible) (Image: Non-compliance … |
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(Image: Attention!) What are the consequences of non-compliance? A proper compaction of the side fill is impossible when the required minimum trench width is undercut. Static assumptions cannot be met in such a case. (Image: Inadequate working space at the side of the pipe – Proper compaction is impossible) |
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What are the consequences of non-compliance? Failure to comply with the minimum specified trench width leads to inadequate compaction of the bedding. This results in overloading of the pipe and cracking at the quarter points or in case of plastic pipes to deformation. (Image: Concrete pipe failure at the quarter points due to insufficient bedding compaction) (Image: Clay pipe failure due to insufficient bedding compaction) (Image: Clay pipe failure … |
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What has to be considered when selecting the trench width? The following details are to be taken into account in the selection of the trench width:
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Animation: Exercise Work safety - Minimum working distance [Animation: visaplan GmbH]. This interactive object is only visible in the online version of the module. |
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The base of the trench is the level onto which the sub base backfill material is placed. (Image: Trench base) (Image: Trench base) (Video: Loosening the trench base with an excavator bucket) Which excavator bucket is suitable for the trench base? Select the correct image by clicking on it. (Image: False excavator bucket) (Image: Correct excavator bucket) |
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The following rules and regulations are applicable in the United States of America (not an exhaustive list):
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The following rules and regulations are applicable in Europe:
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The embedment for standard trenches comprises of four zones: foundation, bedding, haunch, initial and final backfill [[ASTM D2774-12]]. The following image presents the terminology used in open cut installation of underground pipes. (Image: Installation terminology according to ASTM D 2774-12) 1 - Sloped wall (as required) 2 - Trench wall (native) 3 - Final backfill 4 - Initial backfill 5 - Pipe embedment 6 - Haunch zone 7 - Springline 8 - Bedding 9 - Bell … |
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Important: Drains and sewers must be leak-tight, operationally and structurally safe. If the structural stability is no longer given, the other requirements are usually not fulfilled either. As a matter of principle, structures, and thus also drains and sewers, must be designed and manufactured in such a way that they achieve their intended service life under the external and internal loads and stresses acting on them, with unrestricted serviceability. |
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Not all soils are suitable for use in the embedment zone. The following section presents in detail the types of soil that are plausible to use in embedment zones, according to both American and European standards. |
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