Effect of daily fluctuation of groundwater level on land-subsidence

Laboratory oedometer tests were conducted to investigate the effect of small intermediate reloading-unloading (r-u) cycles (in over-consolidated range) on a general unloading path and that of small unloading-reloading (u-r) cycles on a general reloading path on the permanent deformation of Ariake clay samples. The test results indicate that the permanent deformation increased with r-u cycles, and decreased with u-r cycles. The test results were simulated well using an existing static u-r model. Then two case histories of land-subsidence were analyzed. The engineering significance of considering daily variations of ground-water levels on the simulated results has been confirmed by comparing with the field measurements.