This study focuses on developing safe foundation criteria models for building structures on drained-granular soil slope terrains. The study initiated with identifying the local slope categorisation criteria exclusively based on the slope angle, ranging from flat to steep slopes. The standard range of drained shear strength parameters of coarse-grained soils in Sri Lankan slope terrains was then determined and estimated to be; angle of internal friction (∅) = 30 0 to 38 0 and cohesion (𝑐𝑐) = 1.0

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... to 10 kPa. The stability of natural drained coarse-grained slopes has been analysed (through PLAXIS 2D v. 8.2). It revealed that Factor of Safety (FOS) variation against slope angle is non-linear for low and high shear strength slopes and low shear strength-flatter slopes; the FOS reduction rate percentage is low (8.3%) in shallow slopes and rapid (34.2%) for steeper slopes and high shear strength-shallow slopes. It is comparatively low (5.7%) for flatter slopes and relatively low but rapid (18.7%) through steeper slopes. As slopes become deep, an inevitable FOS reduction of 23.1% for low-shear-flatter slopes and 14.7% for high-shear-flatter slopes is evident. Hence, with the same trend of FOS reduction rate of shallow slopes, authors speculate the reason is due to the approach of critical height phenomena. Upon reaching the critical height, the effects of the overburden on FOS reduction diminishes. Under constant geometrical conditions, a FOS reduction of 0.8 x (% reduction of Ø) in high cohesive soils to 1.4 x (% reduction of Ø) in low cohesive soils and about 0.2 x (% reduction of 𝑐𝑐) in high friction soils to 0.4 x (% reduction of 𝑐𝑐) in low friction soils is noted. This observation suggests that FOS is highly sensitive to corresponding shear strength parameters, especially the angle of internal friction. For loaded slopes, FOS response for loads in flatter slopes is less compared to steeper slopes, and minimum for strip footings placed at 2.0 m depth, and maximum for 1.0 m wide pad footings set at 1.0 m depth. Similar responses were observed for natural slopes for low and high shear strength loaded slopes in the FOS-Slope Angle-Slope Height relationship. The width and depth effects on FOS for the same foundation types were found to be negligible for most slopes, except for the low shear strength-steep slopes. Though it is costly and practically difficult to implement in residential areas, FOS can be significantly improved (30 to 40%) with slope modifications and subsequent introduction of tieback type soil anchors. A comprehensive set of foundation criteria models have been proposed for different drained-coarse-grained soil slope scenarios.