Classification and Constitutive Modeling of Sliding-Type Colluvial Materials–Li-Shan LandSlide Area as an Example
Dr. Yii-Wen Pan
|關鍵字:||崩積層;岩體;分類;力學模式;邊坡穩定;Colluvium;Rock mass;Classification;Constitutive Modeling;slope stability|
Colluvium can be regarded as complicated composite geomaterials; its contents may range from soft colluvial soil to very hard rock, hence should be treated and modeled with care. This study carefully selected appropriate approach for borehole exploration. The rock cores retrieved from the exploration were carefully examined to study the fracture nature in the colluvium; the cores were then used for laboratory tests in order to characterize their physical and mechanical properties. The Li-Shan landslide region was taken as a study site in order to investigate the material characteristics and mechanical behavior of the colluvial materials in a “sliding-type colluvium”. Unlike other classification mainly according to the degree of weathering, this study classify the colluvium materials found in the studied region into several types according appeared factors including major material, weak planes/cracks, cementation/fillings, weathering intensity, blocky orientation patterns, and so forth. Various types are identified and classified as follows. The first type is composed of grey slate mixed with yellow clay (Type SY); Type SY is further divided into two sub-types according to the alignment slate blocks in the colluvium. The second type is composed of.gray slate mixed with gray clay (Type SG); Type SG is also further divided into two sub-types according to the alignment slate blocks. The third type is composed of gray slate (Type S); Type S is further divided into two sub-types according to whether or not joints are present. The fourth type is mainly soft stratum which may include gray clay and gray slate fragments (Type C). The last type of colluvial material identified in the studied site is backfill (Type BF). To describe the mechanical behavior of geo-materials in the studied site, the colluvium materials were modeled according to their deformability and fratureness. Materials majorly composed of soft clayey soils tends to behavior as elastoplastic soil, they are modeled as a Mohr-Coulomb material in this study. Weathered rock mass with regular joints were also modeled as elastoplastic geomaterial. However, the elastic stiffness and yielding criterion should take into account the structure pattern of regular joints. Regularly jointed fresh rock mass is modeled as an equivalent anisotropic elastic material. A case study of numerical calculation adopting the aforementioned mechanical models with material parameters estimated from other references was carried out. The result of the numerical simulation seems acceptable.
|Appears in Collections:||Thesis|