Full-Scale Testing of Lateral Pressures in an Expansive Clay upon Infiltration

Full-scale testing of lateral pressures in expansive clay under various saturation conditions is crucial to better understand the behavior of these soils and predict potential damage to structures. However, due to their complexity and cost, only a few full-scale physical testing studies on expansive soils have been reported in the literature. This study aims to provide new insight into the evolution of lateral swelling pressure in expansive soils under infiltration via full-scale physical testing. For this purpose, a heavily instrumented 3-m high masonry wall backfilled with an expansive clay was built and subjected to infiltration. The backfill was compacted in 95% of standard Proctor at a moisture content near optimal to simulate field conditions. The degree of saturation, pore-water pressure, temperature, suction, and lateral and vertical pressures were monitored at different locations during the test. Results showed that the development of lateral pressure is rapid during initial saturation and levels out as the clay approaches saturation levels. This finding highlights the importance of monitoring lateral pressure over time to accurately predict its behavior. The study also found that lateral pressure develops prior to vertical pressure, depending on the area and restraint. The lack of vertical pressure observed during the test is attributed to the continued displacement of the concrete block wall and settlement of the clay with increased area and wet weight of the soil. This finding is important for backfill against basement walls, retaining walls, and foundation units, where the mass of the expansive soil is limited, and effective stress is limited to one dimension.