Highway failure over talc–tremolite schist terrain: a case study of the Ife to Ilesha highway, South Western Nigeria

Abstract

Several failure stretches along the newly completed Ife–Osu–Ilesha highway in South Western Nigeria have been studied. The sub-grade as well as the borrow materials are schist-derived, residual micaceous soils which contain abundant talc and hydromica. The flaky structure of these soils means it is difficult to achieve adequate field compaction. Extensive deposits of amphibolite-derived residual soils also occur in the area, which would provide a more suitable sub-base/fill material. The case study highlights the importance of an engineering geological appreciation of the ground conditions prior to design and construction.