The evaluation of lateral earth pressure of soil mass on geotechnical structures like retaining walls, bridge abutments, excavations has gained tremendous importance from stability assessment point of view, over the past few decades. Understanding the magnitude and distribution of lateral earth pressures allows geotechnical engineers to design structures that can withstand the loads imposed by surrounding soil to greater extent. Accurate assessment of lateral earth pressure helps to prevent structural failures such as tilting, sliding, or overturning. Although most of the researches have been done to determine the lateral earth pressure of structures, generally, resting upon saturated soil, but the presence of negative pore water pressure in case of unsaturated soils can result in much variation in the results. Present study aims to determine the lateral earth pressure of a retaining structure, supported on unsaturated soil using lower bound limit analysis coupled with second order conic programming for optimization with different geometrical orientations. The stability and design of geotechnical structures depend largely on how different orientations, such as wall and slope inclination, affect the lateral earth pressure acting on a retaining wall in unsaturated soils. For vertical wall, the active earth pressure coefficient tends to decrease as the roughness (&delta&prime/ϕ&prime) of the soil-wall interface increases. The active earth pressure coefficient (K_a) typically decreases with a higher friction angle for both clay and sand, regardless of the flow conditions. While K_a is almost identical for all flow conditions for a backfill comprising sand, the flow type has a significant influence on K_a for clayey backfill with infiltration being the most critical flow condition. For the sand backfill, it has been observed that the value of K_a was observed to increase continuously with an increase in the values of slope angle.