梨山崩積層內軟弱材料之力學行為

Abstract

梨山崩積層為大規模岩坡破壞所形成，材料組成為破碎板岩及其風化後產物，由於受到形成年代、形成方式以及一次或多次的相對滑動作用與風化作用等影響，造成材料岩心提取率低、材料性質難以界定。 □研究針對梨山崩積體B-9滑動體之滑動面材料，灰色黏土夾灰色板岩碎屑，進行一系列的一般物理性質、粒徑分析分析、與三軸壓密不排水試驗，同時觀察試體表面與端面顆粒分佈狀況，藉以得到顆粒形狀、含量與排列方式對於滑動面材料行為的影響。研究結果顯示，滑動面材料之岩塊含量低於10%，主要為基質土壤所構成，岩塊最大粒徑2cm左右或更小，岩塊形狀主要有次圓粒狀、圓粒狀、片狀或次稜角狀三種顆粒形狀。滑動面形成原因係由山坡潛移作用形成剪力面滑動造成，因此岩塊排列具有方向性；當岩塊含量低於10%時，不影響材料強度，基質材料為主要影響灰色黏土夾灰色板岩碎屑力學行為的因素，但其岩塊排列方式會影響試體破壞模式。 關鍵字：崩積層、岩塊含量、基質土壤、三軸壓密不排水試驗。

Large-scale of the rock slope failure formed the Li-Shan colluvial deposits. The deposits are composed of fractured slate and its weathered soils. Due to the weathering, erosion, and frequently sliding, the nature of the deposits is heterogeneious. Hence, the mechanical behavior and mechanical properties of colluviual deposits are difficult to be determined because of difficult sampling. The study aims to investigate the mechanical bechanical of the weakest material of the deposits, grey clay with slate detritus. A series of physical property tests and consolidated undrained triaxial tests was performed on the specimens prepared from high quality drilling cores. Based on the experimental results, the influence of slate block content and distribution on the triaxial strength, stress-strain cure, and failure mode is dicussed. According to test results, the rock content of the specimens includes 10% less of slate block and 80 % more of matrix soil (grey clay); three types of the shape of slate block were observed including subround, round, and sheet or subangular. Some of the specimens exhibit the long axis of the slate block parallel to the ends of the core, which reflects the fact that the layer of the deposit (grey clay with slate deteritus) are formed by slope shear failure. Due to the content of slate deteritus less than 10 %, the triaxial strength is not influenced by the content of slate deteritus, but depends on the magnitude of confining pressure. However, the stress-strain cure and failure more are dependent of the distribution of slate deteritus in the specimens.

Key Word : Colluvial Deposits , Mechanical Behavior, Block content, Slate Deteritus, Matrix,Consolidated Undrained Triaxial Test.