Foundation stability on sandy soil due to excessive pore water pressure: laboratory observations

Abstract

Abstract Pore water pressure is a factor which contributes to foundation stability. The change in pore water pressure in soil mass may affect the bearing capacity of the foundation. Especially for sandy soil, the increased pore pressure may cause the foundation collapse. This study investigates the stability of soil-foundation system due to the increase of pore pressure using a scaled model in the laboratory. The sands were taken from Siteba Padang and sieved pass through sieve no. 40. The calculated relative density of sample in the box model is 51.76%, which indicated the medium sand density. The model was made up to obtain saturated condition. The increased pore water pressure was performed using upwards seepage method in several steps, which are monitored through piezometer pipes. The tests results show that at the last step, the sand boil happened on the soil surface that result the sink of foundation model. It also indicates the loss of bearing capacity due to the loss of effective stress in the soil mass. The Mohr-graphs is also performed to figures the stress in the soil mass. The graph also can show the collapse points in the soil mass during the test.