The shear strength behavior associated with a large shear deformation of both the fine- and coarse-grained unsaturated soils is important in interpreting and forecasting the initiation and movement of landslides. For this reason, a suction-controlled ring shear apparatus was designed by introducing modifications to the conventional Bromhead ring apparatus extending the axis translation technique. A series of suction-controlled ring shear tests were performed on fine- and coarse-grained unsaturated soil specimens subjecting to large shear deformation. The experimental results are presented and interpreted for highlighting: (i) the shear stress/void ratio-shear displacement relationships; (ii) the envelopes of the residual shear strength; (iii) the void ratio, water ratio and degree of saturation of the fine-grained soil specimens sheared to the residual state under different net normal stresses and matric suctions. These results provide valuable information toward understanding and interpreting the behaviors of landslides in unsaturated soils that experience the first failure and the reactivation along a pre-sheared slip surface.

中文翻译：

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吸力控制环剪试验中非饱和土的力学行为


与细粒和粗粒非饱和土的大剪切变形相关的抗剪强度行为对于解释和预测滑坡的发生和移动非常重要。为此，通过对传统的 Bromhead 环装置进行修改，扩展了轴平移技术，设计了吸力控制的环剪切装置。对承受大剪切变形的细粒和粗粒非饱和土试件进行了一系列吸力控制环剪试验。实验结果的呈现和解释是为了强调：（i）剪切应力/空隙比-剪切位移关系； (ii) 残余剪切强度的包络线； (iii) 不同净法向应力和基质吸力下剪切至残余状态的细粒土试件的空隙率、含水率和饱和度。这些结果为理解和解释非饱和土中滑坡的行为提供了有价值的信息，这些滑坡经历了沿着预剪切滑面的第一次破坏和重新激活。