Verification of Testing Procedure for Critical State Parameters on an Unsaturated Silty Soil

• Main Authors: Chin-YuChang, 張瑾瑜
• Other Authors: Wen-Jong Chang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/34150521731837363807

碩士 === 國立成功大學 === 土木工程學系碩博士班 === 101 === Critical state soil mechanics has been well recognized for prediction the behaviors of saturated soils. Although unsaturated critical state soil models have been proposed, the development is slow due to limited testing data and highly complexity of the testing procedure. This experimental study aims to verify the testing procedure of unsaturated triaxial tests up to the critical state. A miniature suction probe used to monitor the suction in the middle plane and an inner cell system for total volume measurement are integrated in a triaxial testing system for unsaturated triaxial and isotropic consolidation tests. The maximum ratio of excess suction during shearing is used to determine the testing strain rate. Unsaturated triaxial tests of a silty soil with constant suction in drained condition were performed. The testing result reveals that the silty soil reaches critical state at 30% axial strain with constant excess suction, volume, and deviator stress. The critical state parameters are determined from the critical state line (CSL) on p-q and p-v planes and the consistence of the results confirms the validation of the testing procedure in this study. This experimental study also finds that the normal consolidation line is not parallel with the CSL for unsaturated soils, while in saturated soils they are parallel with each other.