Effect of overconsolidation on K₀in centrifuge models using CPT and tactile pressure sensor

Assessing the state of stress in soil in the free field, as defined by the vertical and lateral earth pressures, is important in some geotechnical problems such as the design of underground structures and estimation of soil liquefaction potential. Unlike the vertical earth pressure, several factors can influence the lateral earth pressure, particularly overconsolidation. This is typically accounted for by relating the coefficient of lateral earth pressure at rest, K₀, with the estimated overconsolidation ratio (OCR). The corresponding relations available in the literature are related to the K₀ occurring for a given OCR during unloading, and do not take into account the unloading-reloading effect that may be present in centrifuge tests. In this paper, the relationship between the coefficient of lateral earth pressure at rest, K₀, and overconsolidation ratio, OCR, is investigated for the whole loading-unloading-reloading condition. Four centrifuge model experiments were conducted on Ottawa F#55 sand. Two of the models were tested using a tactile pressure sensor to measure K₀ and the other two models were tested using a miniature cone penetration test (CPT) system. The paper concludes with recommendations for centrifuge operation when testing overconsolidated sand in the centrifuge.