Stronger soil layer within a layered slope is of no concern as the stronger soil layer provides extra stability. But if the relatively stronger soil layer has less permeability, it will cause hindrance to the natural infiltration processes and makes the slope vulnerable. This paper presents the results of a series of laboratory tests and numerical analyses on 45 degrees inclined homogeneous and non-homogeneous unsaturated sandy slopes subjected to continuous rainfall. The non-homogeneous slopes consist of less permeable but stronger silty-sand (NH) layers located at different locations of an otherwise homogeneous sandy soil slope. It is observed that the inclusions of NH layers within the homogeneous sandy slopes trigger a failure during continuous rainfall. The NH layers prevent the seepage of the infiltrated rainwater through the slope. As a result, the water content increases rapidly just above the NH layers and consequently the suction pressures in the soil and its shear strength just above the NH layers decrease. With the rainfall duration, the positive pore water pressures buildup just above the NH layers. This induces a slope failure with the failure plane passing above the NH layer. A discontinuity of the shear plane is also observed in the case of a multiple NH layered soil slope.
来源平台：BULLETIN OF ENGINEERING GEOLOGY AND THE ENVIRONMENT
