(1. Institute of Geotechnical Engineering，Zhejiang University，Hanghzou，Zhejiang 310027，China；2. Key Laboratory of Soft Soils and Geoenvironmental Engineering of Ministry of Education，Zhejiang University，Hanghzou，Zhejiang 310027，China； 3. CCCC FHDI Engineering Co.，Ltd.，Guangzhou，Guangdong 510230，China)
Abstract：A number of K0-consolidation tests are carried out on the undisturbed mud/silt clay and silty clay samples of Hong Kong—Zhuhai—Macao bridge by using advanced triaxial apparatus. The changes of static soil pressure coefficient K0 under different loading and unloading paths are studied；and the applicability of using common formula and recommended value of specifications to estimate the K0 are analyzed，as well as the prediction equation based on test results is given. The results show that：K0 of mud/silt clay at the bottom of the Hong Kong—Zhuhai—Macao bridge immersed tunnel is a basically constant value(0.47). K0 of silty clay is proportional to the preconsolidation pressure and K0 is between 0.30 and 0.45；both of the bounds are lower than the recommended values of specifications and manuals for similar soil. In addition to soil properties，the cementation of the undisturbed samples also could make the K0 reduce. K0 of the strong structural undisturbed soil would decrease to below the values of normally consolidated clay and then rebound and gradually stabilize during loading stages. We can use the empirical formula given by the predecessors to estimate the K0 of normally consolidated and over-consolidated undisturbed clays；and the internal friction angle should be the effective peak internal friction angle of normally consolidated soil.
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2013, Vol. 32 
