Assessment of Cracks on a Building at Tarkwa in Ghana with Respect to Foliations and Joints in Foundation Tarkwaian Rocks
Tetteh G. M.1*, Mensah F. A.2
Citation : Tetteh G. M., Mensah F. A., Assessment of Cracks on a Building at Tarkwa in Ghana with Respect to Foliations and Joints in Foundation Tarkwaian Rocks International Journal of Mining Science 2016, 2(1) : 25-32
Buildings constructed with bricks develop cracks and other structural damages after minor foundation displacements or settling from loading. The defects are formed because foundation rock quality deteriorates due to inherent discontinuities such as faults, joints and weathering which reduce the bearing capacity of the foundation rocks and soils. These can affect the structural integrity of the building resulting in cracks or collapse of the building. This paper highlights cracks on the building which was previously used by Ghana National Fire Service at Tarkwa, in the Western Region of Ghana in 2007 before it was pulled down for a new structure to be built. The investigations on the cracks involved taking strike, dip and dip directions, length, and extent of separation. These data were compared with measurements of foliations and joints on Tarkwaian conglomerate and quartzite outcrops close to the area. The study revealed that the cracks on the building were almost horizontal with some vertical deviations. The cracks generally strike northwest, almost perpendicular to the strike direction of the foliations and joints in the Tarkwaian rocks which mostly strike south-south west. The major crack separations were extensive along directions of SSW (65-92mm), NW (70mm), E (42mm) and NE (25mm). These suggest that the building was settling in a major direction parallel to the general strike of the major joints and foliations and along their main dip direction. Visual examination of cracks indicated that, a few of the cracks might have been accentuated by ground vibrations from the heavy trucks on the nearby major road.