Lumpy soils are inhomogeneous materials which can be encountered in open pit mining. The initial structure of the clayfills is similar to that of the granular material, which is stable due to the absence of a reconstituted soil. However, it might be transformed into a lumpy-composite structure due to the influence of climate. The lumps are randomly distributed in the reconstituted soil, which can be bounded by two basic configurations. For this purpose, two series of triaxial shear tests were performed on artificially prepared samples with parallel and series configurations of the different constituents. The test results show that the shear strength of the series samples is only slightly higher than that of the weaker constituent and the strength of the parallel samples lies between those of the constituents. For the parallel samples, there is a significant difference in the stress concentration ratio at different consolidation stress; while, the strain concentration ratio of the series samples is not significantly affected by the consolidation stress.