On Strength Characteristics of Saturated Silt under Excavation Unloading Path
In relation to the foundation pit engineering of Fujian Road Metro Station in Nanjing,conventional shear test on saturated silt and a series of K0 consolidated-drained triaxial shear tests under different stress ratio were carried out to study the strength characteristics of silt under different unloading paths.The result shows that,the stress-strain characteristics of saturated silt relates to the stress path closely,when the stress ratio of lateral unloading to bidirectional unloading is less than 1,there presents compression failure,when the stress ratio of axial unloading to bidirectional unloading is larger than 1,there presents tensile failure;the compression failure with increased deviatoric stress,and the tensile failure with decreased deviatoric stress,have different critical state lines;in the axial unloading zone at the bottom,the internal friction angle measured by the conventional triaxial test is significantly larger,causing the calculation value of the passive earth pressure at the bottom to be of unsafety.
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