The Yaramoko Mine project is located in Bagassi, approx. 270km south of Ouagadougou the capital of Burkina Faso. 

BAUER Engineering Ghana Ltd was awarded a second contract for the installation of the secant retaining wall for the circular 55Z East ventilation shaft 2, centre pile and foundation support piles as part of the mine extension.

 

The 55Z East circular shaft is to be used for the ventilation of the extension of the Yaramoko South underground gold mine. The 3.5m diameter circular shaft was executed with piles with a max. depth of 24m. The embedment depth of the piles into the rock was between 0.5m and 1.0m. 

 

Geology:

Overburden consisting of sand and gravel

Bedrock

 

Scope of Works:

• Guide wall for the secant pile wall
• 14 nos secant piles dia. 1180mm, 23m deep for one circular ventilation shaft.
• 4 nos foundation piles dia. 1180mm, 23m deep for the support of the vertical drilling system
• 1nos, centre pile dia 1180mm, 23m deep for the pilot hole drilling of the Raise bore rig

 

Miscellaneous:

The bored piles have a nominal diameter of 1180 mm in overburden soil and had to be embedded into the rock (used drilling tool with Ø 1060 mm). The embedment depth into the rock length was varying depending on the in-situ geological ground conditions. And approx. 13m to 15m of temporary casing were installed during the drilling. The secant pile wall was executed as “hard / soft” pile wall with sufficient pile overcut to ensure the technical design requirements. In addition, the secondary piles had to be reinforced full length.

 

 

INFO

Construction Methods:           Secant pile wall

Constructions Materials:        Concrete, steel

Main Equipment:                    BAUER BG 28

Construction period:               February 2020 – March 2020