梨山崩積層中類併構岩（板岩夾黏土）之力學行為

Abstract

梨山崩積地層主要由破碎板岩及其風化形成的土壤所組成，後經侵蝕作用造成凹凸之緩起伏地形，此種地形、地質條件極易於豪雨或地震後產生滑動。由於崩積材料組成甚為複雜，邊坡分析、設計所需瞭解的崩積層力學行為及力學參數甚難決定。本研究視梨山崩積層之破碎岩塊夾板岩風化後的黏土為倂構岩，旨在以實驗室三軸試驗探討崩積倂構岩的力學行為，並提出決定力學參數的方法。 本文利用軟岩用三軸試驗系統進行一系列的三軸不排水試驗探討不同岩塊含量對應力應變曲線、破壞形式、彈性模數、三軸破壞強度等的影響。試驗結果顯示岩塊的尖峰軸差強度、及切線楊式模數皆隨著岩塊含量增加而有上昇之趨勢。而岩塊含量較少的試體在模數隨變形量折減時有較大之折減情形。由試體破壞形示發現，高含量之試體受到岩塊排列影響，破壞面呈蜿蜒曲折狀，且破壞面上岩塊與岩塊間有摩擦之情形，增加了試體破壞面的粗糙度，推測此為造成併構岩材料強度增加之原因。最後本研究並提出結合室內試驗與數值模擬進行決定併構岩力學參數之方法。

The Li-shan colluvial deposits are composed of broken slate and its weathered soils. The ground surface exhibits concave-convex landforms which were formed by weathering and erosion. Thus, the terrain and geology exlpicit that landslide is easy to be triggered by rainfall or earthquake in the area. Due to the heterogeneity nature, the mechanical behavior and mechanical properties of colluviual deposits are difficult to be determined. Based on the nature, the broken slate with grey clay of colluvial deposits in Li-shan area can be categorized as a BIM (block in matrix) rock. The study aims to invstigate the mechanical behavior of the BIM rock. A series of undrained triaxial compression tests was performed on the BIM rocks. Based on the experimental results, it can be found that both the triaxial peak strength and tangential Young’s Modulus of the BIM rock increase with the increase of block content in specimens; the degree of modulous degradation for lower-block-content specimens is more significant than that for higher-block-content specimens. After observing failed specimens, it was found that failure path of high-block content specimens is zigzag and the blocks located on the failure surface were sheared. The fact can be explained that the larger of the block ratio of the specimen is the higher of the triaxial peak strength of the BIM rock. Finally, an approach is recommended for determining the mechanical properties of BIM rocks by laboratory trial compression test associated with numerical analysis.