응력이력이 사질토의 CPT-DMT 상관관계에 미치는 영향

Abstract

Stress history increases the residual horizontal stress of granular soil and, consequently, the penetration resistance. This study analyzes the effect of stress history on the cone resistance (qc), horizontal stress index (KD) and dilatometer modulus (ED) of CPT and DMT from calibration chamber specimen in OC as well as NC state. Test results show that the normalized cone resistance by mean effective stress correlates well with the relative density and the state parameter, whereas the normalized cone resistance by vertical effective stress is a little affected by stress history. The influence of stress history is more reflected on KD than ED and qc. The KD/K0, in which the effect of stress history on KD is compensated by the at-rest coefficient of earth pressure, K0, is related to relative density, state parameter and the normalized cone resistance by mean effective stress. It is also observed that the normalized dilatometer modulus by mean effective stress (ED/σm') shows a unique correlation with the state parameter, regardless of stress history.