Semantok Dam Cut-off Wall

Nganjuk, East Java – Indonesia.

Un-reinforced secant pile wall diameter 880 mm with depth up to 25 m cast with plastic concrete is constructed for a new dam cut-off wall, spacing 640mm c/c to have minimum wall thickness 600mm after overcutting. The specification of this wall is to have a cut-off wall with an elasticity modulus equal to maximum 5 times from the surrounding ground material. Permeability test is mandatory for this wall, and the coring position is on the overcutting area (in between the primary & secondary). Works were carried out from various working platform levels which follow the cut-off trench level that is equal to the pile cut off level (COL). Due to the low plastic concrete strength, it needs special attention for secondary pile drilling process to avoid cracking the primary pile. All permeability tests, which is the key to the success of this project, gave results much higher than the requirement. 2 unit of BG 28 was utilized in this project.


Construction period:

November 2019 – June 2020