|
|
As a part of the execution planning, a detailed design of the sewer lines and structures is prepared, and includes the following components:
|
|
|
(Image: Installation of gas- and water supply lines and sewer in a trench - Image 2) If there are several pipes (e.g. supply- and disposal piping) installed in one trench, the required material- and system-dependent minimum distances have to be kept. |
|
|
The following information includes some of the details required by, and for, the successful execution of work:
|
|
|
Where required, the limiting values for deviations from the determined lateral and vertical position of the pipe are to be specified. They depend primarily on the following factors:
|
|
|
(Image: Attention!) It is important to note that the materials used in the construction process should not negatively affect the structural components or the groundwater and soil. |
|
|
Apr 17, 2019 |
|
|
Apr 17, 2019 There has to be a contractual settlement between the client and the contractor with respect to the following items on the agenda:
|
|
|
Apr 17, 2019 (Image: Open cut method of construction – Built-up area in the zone of influence of the building pit) Prior to the start of the civil engineering works, the exact position of the structures (buildings, piping, cables etc.) within the construction area of the excavation is to be crosschecked by the contractor. The trench construction process should never result in deformations or settlements of the surrounding structures. It is important to ensure that … |
|
|
Apr 17, 2019 Depending on the individual requirements, the open cut method of construction allows for different cross sections of utility trenches, ranging from the sloped trench to trenches with vertical faces [Stein88d]. Combinations, such as stepped trenches with vertical, sloped or partly sloped trench walls, can also be found. (Image: Cross sections of utility trenches for the installation of sewers by means of the open cut method of contruction in accordance … |
|
|
(Image: Attention!) Excavations and trenches are to be sloped, lined or secured in any other way in order to ensure that they remain stable during all individual states of construction. All conditions and influences that could have a negative effect on the stability of the excavation walls or trench walls are to be taken into account, particularly the differences in the behavior of non-cohesive and cohesive types of soil. (Image: Unshored trench with … |
|
|
Apr 17, 2019 OSHA defines cohesive soil as "clay (fine grained soil), or soil with a high clay content, which has a cohesive strength. Cohesive soil does not crumble, can be excavated with vertical sideslopes, and is plastic when moist. Cohesive soil is hard to break up when dry, and exhibits significant cohesion when submerged. Cohesive soils include clayey silt, sandy clay, silty clay, clay and organic clay." [[OSHA 29 CFR 1926 Subpart P App A]] Non-cohesive … |
|
|
Apr 17, 2019 (Image: Attention!) (Image: Trench excavation úsing a crawler excavator) During the excavation process, it is necessary to inspect the in-situ soil in order to ensure that it’s properties match the assumptions that have been made in the structural calculations (e.g. by means of soil identification). In case of deviations, it is imperative to inform the construction supervisor or structural engineer. |
|
|
Existing piping and cables need to be taken into consideration when working in urban locations. In case of doubt, it is recommended to excavate the area in question using hand tools or hydro or vacuum excavation in order to determine the exact position of other services, as their actual position very often deviates from the planning drawings. Located services need be properly secured through suspending, supporting, rerouting etc. measures as specified … |
|
|
Apr 17, 2019 To ensure the stability of the excavation, the trench construction must comply with national construction safety standards, and excavation safety regulation, by providing sloped walls in unlined trenches, and shored walls in vertical trenches. The type and extent of the required trench safety measures is dependant on the in-situ soil type, groundwater conditions, and the depth of the trench. (Image: Unlined trench – sloped trench walls) (Image: Shored … |
|
|
Apr 17, 2019 In order to assess the stability of the trench, the following information is generally required:
|
|
|
Apr 17, 2019 (Image: Overview of possible measures used to secure open cut trench walls) |
|
|
Apr 17, 2019 |
|
|
Apr 17, 2019 The Occupational Safety and Health Administration (OSHA) Excavation and Trenching standard, Title 29 of the Code of Federal Regulation (CFR), Part 1926.650, covers requirements for excavation and trenching operations. A trench is defined as a narrow underground excavation that is deeper than it is wide, and no wider than 15 ft (4.5 m) [[OSHA CFR 29, Part 1926.650]] (Image: Cross sections of utility trenches for the installation of sewers by means of … |
|
|
Apr 17, 2019 OSHA requires that all excavations in which employees could potentially be exposed to cave-ins be protected by:
Additionally, temporary soil must be placed no closer than 2 ft (0.61 m) from the surface edge of the excavation, measured from the nearest base of the spoil to the cut. The … |
|
|
According to [[OSHA CFR 29, Part 1926.650]], the excavation does not require a protective system when it is:
Some European countries have stricter limits. Here only excavations and trenches up to a depth of 4 ft (1.25 m) may be constructed without additional shoring. Further information can be found … |
|
|
Apr 17, 2019 |
|
|
Apr 17, 2019 BE-02 Open Cut Method: Utility Trench Construction - v01 Trench Without Support System as per International Standards Excavations and trenches up to a depth of 4 ft (1.25 m) may be constructed without additional shoring of the vertical walls if the adjacent ground surface
(Image: Securing of unlined trenches and shafts at depths of ≤ 1.25 m/4 ft in accordance with [DIN4124c] – Vertically sloped trench walls) (Image: Lack of shoring, although … |
|
|
Apr 17, 2019 AE-02 Open Cut Method: Utility Trench Construction Trench Without Support System as per International Standards Excavations and trenches up to 6 ft (1.75 m) in depth may be excavated, if the portion of the trench wall above 4 ft (1.25 m) from the trench base is sloped at the angle β ≤ 45° and …
(Image: Securing of unshored trenches and shafts at depths of > 1.25 m/4 ft and ≤ 1.75 m/6 ft in accordance with [DIN4124c] – vertically sloped trench walls with sloped edges (… |
|
|
Apr 17, 2019 BE-02 Open Cut Method: Utility Trench Construction - v01 Trench Without Support System as per International Standards The securing of trenches up to a depth of 6 ft (1.75 m) using only a timber plank is no longer permissible. This case requires a partial shoring of the trench walls above 4 ft (1.25 m) from the trench base. Right Wrong (Image: Cosmetic, respectively non-functional … |
|
|
Apr 17, 2019 |
602 search results:
