This paper presents a centrifugal model test on the coefficient of lateral earth pressure at rest, K_0 in a compacted unsaturated clay fill. The clay fill was first compacted to achieve a dry density of 1.55 g/cm~3 and then wetted to an expected water content gradient along the depth direction. It was accelerated in several stages to a maximal acceleration of 100 g in the test. The vertical and horizontal earth pressures were recorded with miniature earth pressure transducers embedded at different depths in the clay fill. Moreover, the surface settlement, matric suction and water content were measured during the test. It was found that the vertical earth pressure can be properly calculated with unit weight, depth and acceleration. It was also shown that K_0 for normally consolidated unsaturated clay is less than that for saturated clay, and increase with increase of water content, regardless of centrifugal accelerations.
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