Characterization of Yangsan Clay,Pusan, Korea

It has been reported by previous researchers that the preconsolidation pressure (p_c) of Kimhae (Yangsan) clay, which is thickly deposited along the Naktdong River, Pusan, Korea, is considerably less than its in-situ effective overburden pressure (p'_vo)-The question has arisen whether such a low p_c value is due to underconsolidation or to the unreliability of laboratory tests, including the use of low quality sample. As a cooperative research program between PHRI (Port and Harbour Research Institute) and Pusan National University, extensive in-situ and laboratory investigations were carried out at Yangsan, using a Japanese sampler and Japanese sampling technique. It is found that the p_c values at the site are slightly greater than p'_vo, which is different from the test results from the previous researchers. However, the overconsolidation ratio (OCR) at this site is quite small compared to similar aged normally consolidated clays deposited in Japan.