不同排水條件/滑移速度條件下高嶺土之摩擦特性探討

Frictional Characteristics of Kaolin Clay Under Different Drainage Conditions and Shear Speeds

李羿葦(Yi-Wei Lee) ； 楊哲銘(Che-Ming Yang) ； 董家鈞(Jia-Jyun Dong)

《中華水土保持學報》 47卷4期 (2016/12) Pp. 191-199

https://doi.org/10.29417/JCSWC.201612_47(4).0003

摘要

本研究探討滑移速度和排水條件對高嶺土摩擦係數之影響。使用高速旋剪試驗儀，以正向應力1 MPa、滑移速度10^(-6)～1 m/s 進行旋剪試驗，量測浸水高嶺土視摩擦係數，排水條件可分徑向排水與單、雙向排水。結果顯示徑向排水 (較接近不排水) 試驗在任何滑移速度下，穩態摩擦係數較單、雙向排水試驗結果為低，且徑向排水試驗於試驗前期 (＜200 秒)，摩擦係數將先降至一低點後再逐漸上升。當剪動速度達1 m/s 時，三種排水條件之試體均由較低速情況下之位移強化轉化為位移弱化。本研究推論這些現象與不同排水條件、不同剪動速度造成之不同超額孔隙水壓累積有關，本研究結果顯示潛移邊坡轉化為加速滑移可能會與滑動面排水條件有關，邊坡位移速率監測管理值之訂定可能也有必要考慮滑動面排水條件。

關鍵字

超額孔隙水壓 ； 滑移速度 ； 摩擦係數 ； 高嶺土

並列摘要

This study aims at exploring the influences of shear velocity and drainage conditions on the strength of kaolin clay. A low to high velocity rotary shear apparatus was used to measure the apparent friction coefficient of wet kaolin clay under a normal stress of 1 MPa. The shear velocity ranged from 10^(-6) to 1 m/s. The drainage conditions include radial, single and double drainage conditions. The results show a lower strength for the radial drainage condition (close to the undrain condition) than the ones measured under single drainage test conditions covering the whole velocity spectrum. Notably, the friction coefficient dropped rapidly in the early stage (＜200 s) of radial drainage condition but increased gradually, which can be related to the excess pore pressure dissipation. The results of this study are relevant to the study of large landslides, from creeping tuning to catastrophic failure.

並列關鍵字

Excess pore water pressure ； shear speed ； friction coefficient ； kaolin clay/kaolinite