|
|
(Image: Example for non-compliance to the minimum required distance) (Image: Example for non-compliance to the minimum required distance) It has to be ensured that road vehicles and, in particular, construction equipment, are kept at a sufficient distance from the trench in order to prevent overloading the trench shoring. The following minimum distances are to be kept for horizontally and vertically lined trenches:
|
|
|
(Table: Minimum required distances for vehicles and construction equipment in accordance with DIN 4124a) |
|
|
|
|
|
Aug 22, 2016 The installation methods of trench lining elements are basically classified into the insertion method and the cut and lower method. |
|
|
Aug 22, 2016 The insertion method involves first excavating the trench, and then inserting the shoring elements into the temporarily stable trench. Worker access to the trench is only permissible upon the successful installation of the shoring. (Image: Insertion method - Step 1: Provision of a suitable trench shoring system (Height = depth of the shaft + 10 cm)) (Image: Insertion method - Step 2: Excavation up to the full depth of the shaft) (Image: Insertion method - … |
|
|
Aug 22, 2016 In the cut and lower method the soil is excavated in stages between the panels, which are alternatingly forced into the soil one side at a time. (Image: Cut and sink method – Step 1: Excavation) (Image: Cut and sink method – Step 2: Insertion) (Image: Cut and sink method – Step 3: One side is sunk and the other excavated) (Image: Cut and lower method – Step 4: One-sided force pushing the lining element deeper into the subsoil and one-sided excavation) |
|
|
Aug 22, 2016 In the cut and lower method the soil is excavated section-wise in-between the panels, while the lining elements are forced into the in situ soil simultaneously on both sides. Step 1 (Image: Cut and sink method (double-sided) - Step 1: Provision of a suitable trench lining system (Height = Depth of the shaft + 10 cm)) Step 2 (Image: Cut and sink method (double-sided) - Step 2: Excavation) Step 3 (Image: Cut and sink method (double-sided) - Step 3:) Step … |
|
|
Aug 22, 2016 Standard trench shoring No uninterrupted force-locked connection between the trench shoring and subsoil during the lowering process. (Image: Standard trench lining) (Image: Standard trench lining) Linear shoring with boogie car (roller frame) Uninterrupted force-locked connection between the trench shoring and subsoil during the lowering process. (Image: Linear shoring with boogie car (roller frame)) (Image: Linear shoring with boogie car (roller frame)) |
|
|
Aug 22, 2016 Insertion of linear shoring support elements with roller frame in practice: The uninterrupted force-locked connection between the trench shoring and the subsoil is guaranteed. (Image: Insertion of linear shoring elements with roller frame – Forcing the panel deeper into the soil) (Image: Insertion of linear shoring elements with roller frame – Insertion of another panel) (Image: Insertion of linear shoring elements with roller frame – Flush insertion … |
|
|
|
|
|
|
|
|
For the installation of pipelines and sewers in areas with groundwater, the trench has to be kept free of water. There are three water retention methods available for that purpose:
Subsequently, the first two options will be considered in detail. (Image: Groundwater lowering using wells – Detail: … |
|
|
Open dewatering involves simultaneously collecting accruing groundwater water during the excavation process. This process is performed at about 20 in to 40 in (50 cm to 100 cm) ahead of the excavation, and requires stable types of soil (such as rock), coarse gravel or cohesive types of soil and generally low permeable soils to be effective. The groundwater can be directly pumped or allowed to seep to sumps at the boundaries of the trench, where it … |
|
|
(Image: Groundwater lowering using wells) In the groundwater lowering method, vertical wells as well as required piping and pumps are installed around the planned trench or construction pit (in the case of large construction pits also within the pit) prior to the excavation process. Compared to the open water retention method, groundwater lowering by means of wells allows for significantly deeper lowerings. The design type and dimensioning of the well … |
|
|
(Image: Installation of wellpoints for groundwater lowering using gravity drainage) (Image: Groundwater lowering using gravity drainage- mode of operation) (Image: Installation of wellpoints for groundwater lowering using gravity drainage) Basically, we distinguish between gravity drainage and vacuum drainage systems. In the case of gravity drainage, the lowest groundwater level can be found in the well pipe. Consequently, due to gravity, the water … |
|
|
(Image: Example for groundwater lowering using vertical wells (well lowering)) If the subsoil is very impermeable (fine sands and silts (kf = 10-4 – 10-7 m/s)), a vacuum drainage system is used. In contrast to gravity drainage, an additional pump-created vacuum is used to direct the water to the wells. (Image: Groundwater lowering using vacuum drainage (deep well system) – Detail header pipe) (Image: Groundwater lowering using vacuum drainage (deep … |
|
|
(Image: Example for horizontal water collection) Instead of vertical wells, horizontally arranged filters or drainage pipes can also be installed next to the excavation (or even below larger excavations). The so-called horizontal water collection significantly reduces the water quantity to be pumped. However, the additional costs for the installation of this system are only economical for long-term construction measures. |
|
|
|
|
|
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! |
|
|
Aug 22, 2016 The construction of sewers is still often carried out in the form of open cut construction. Depending on the design, this results in different pipe-soil systems with different external loads on the sewer. After completing this module, you will have a sound knowledge of:
|
|
|
(Image: Open cut trench working space) The trench width has always been the subject of discussions due to its impact on the economic efficiency and the quality of pipe installation. The trench width should be dimensioned in such a way as to provide sufficient working space around the pipe. The working space is considered to be the area at the base of the trench measuring from the outside edges of the pipe to the inside edge of the shoring or the trench … |
|
|
(Image: Question). What kind of failures or problems are visible in the images? (Image: Inadequate working space at the side of the pipe (no arrow)) (Image: Inadequate working space at the side of the pipe – Proper compaction is impossible) |
|
|
The minimum trench width defines the minimum working space in the trench needed to enable proper compaction of the haunch zone and of the embedment. A definition of the minimum trench width can be found for example in the European standard [EN1610:2015]. The minimum trench width is a function of both the nominal pipe size and the trench depth. (Image: Minimum trench width subject to the nominal pipe size) (Image: Minimum trench width subject to the … |
|
|
The abbreviation for the nominal size of the pipe is DN (Diameter Nominal) or ID (Internal Diameter). It defines the parameter for circular cross sections in millimeters (without specifying the unit mm). The nominal size approximately corresponds to the clear diameter. (Image: Attention!) The minimum trench width is determined solely by the OD = outside diameter of the pipe. Non-circular cross sections are classified into DN groups with the help of … |
|
|
Standards, specifications and installation guidelines used in the United States are specific and unique for each pipe material, therefore, unlike the European standards, there is no general approach documented in one single standard related to minimum trench width calculation. As a result, the most common practice in the US is for the engineers and contractors to follow the specifications imposed by the pipe manufacturer, or the specifications prescribed … |
11094 search results:
