Shear strength parameters of slope cover soils from Sypka Mts (Wiśnieckie Foothills), where in May and June of 2010 were activated massmovements, are presented in the paper. Mainly loamy gravels (colluviums material) and silty sands (slipping surface soil) were the main soils of slope cover, but were also locally observed silt and shales. Shear strength tests were carried out in direct shear apparatus of dimensions of the box 60 × 60 mm and some tests of silt were done in traxial apparatus. Tests were carried out for saturated as well as unsaturated soil samples. Shear strength test results of saturated soils revealed that loamy gravels and silty sands had great values of angle of internal friction and varied values of cohesion, where smaller ones were obtained for silty sands. In turn, test results of unsaturated sand and silt revealed that decrease of moisture content caused significant increase of shear strength of soils, but the increase was mainly effect of changes of apparent cohesion. Comparison of direct shear and traxial test results of silt gave very similar values of angle of internal friction and cohesion. The multiple shearing of shale caused decrease of the initial shear strength by 24−36% and value of residual angle of internal friction calculated directly on test results was equal to 18°.

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