The Technical Reference is specific to the design and construction of deep excavations.
Deep excavation refers to any excavates which has a retained height or excavation depth of 6 m or more. This includes shafts, trenches, cofferdams, marine or land retaining structures with walls, both temporary and permanent, ranging from free-standing gravity walls to multi-braced or anchored embedded walls. For a sloping ground behind the retaining wall, the height is taken to be from the excavated level to the top of slope. The excavation depth includes smaller but separate excavations or holes which extend beyond the main excavation level for construction of pile caps, pump sumps, lift pits etc.
This Technical Reference is also applicable to situations where the excavation depth or retained height is less than 6 m if any of the following conditions is met:
a) There are adjacent structures within a horizontal distance of less than the excavation depth from the excavation face that are vulnerable to or likely to be adversely affected by the excavation works;
b) Ground conditions are poor; or
c) Lowering of groundwater table will likely lead to significant consolidation settlements in surrounding ground.
TR 26-2010 history
2010TR 26-2010 Technical reference for deep excavation
1990TR 26-1990 Planning and Installation Guide for CSMA/CD 10 Mbit/s Baseband LAN Coaxial Cable Systems (2nd Edition)