Elucidating the Slope Stability of the Coastal Range Focusing on Suilien Conglomerate Slope

• Main Authors: Pei-Chen Chan, 詹佩臻
• Other Authors: 翁祖炘
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/4d3du5

碩士 === 國立臺北科技大學 === 資源工程研究所 === 97 === In nature, weathering causes rocks to have a lower strength and hence greater deformation. It is, therefore, an important factor which needs to be considered for designing safe engineering structures. However, no systematic study has been done for measuring the influence of the degree of weathering on the stability of structures. In this study, the primary focus has been on the Suilien Conglomerate Slope of the Paliwan Formation in the Taiwan Coastal Range. Using the limit equivalent method for back analysis, the mechanical parameters of the slope were found. The effect of these parameters on the terrain properties was discussed. This article investigates the variation of the mechanical and the mineralogical properties under the weathering process produced by means of artificial circulations on rapidly changing environmental conditions like temperature, moisture and acidity. The effect of weathering on the mechanical characteristics and on the microscopic texture of the Suilien Conglomerate was hence found.The variation of mechanical and mineralogical properties of Suilien Conglomerate during artificial weathering process was thus investigated. The mechanical parameters of the rock sample were obtained from Rock Mechanics Laboratory tests and at the microscopic level it was calculated using the Discrete Element Method (DEM) and both were compared to each other. A comparison was also made between the macro parameters (mechanical parameters obtained from the Slope Stability) and the parameters obtained from the Rock Mechanics Laboratory tests. This comparison was made using the Finite Element Method (FEM). Using the above two comparisons, a relationship was developed between the degree of weathering and the Factor of Safety of the slope. The diagenesis time of the rock was short and therefore the cementation between its grains was weak. This weak cementation was a major cause for the variation of its mechanical properties. Testing results show that the strength, slaking and the durability index of conglomerate decrease with the increase in the number of cycles, and the variation of apparent frictional properties, with obvious anisotropy, is highly influenced by the decomposition or dissolution weathering mechanism. Since the matrix is weakened by the weathering process, it cannot hold the quartz grain. This leads to its loss as confirmed by the study of its mineralogical properties. And using DEM to simulate UCS, we find that the following parameters are affected by the degree of weathering: matrix strength, cement strength, matrix Young’s modulus and friction. The factor of safety is controlled by the matrix strength and the cement strength. Lower these parameters; less is the factor of safety.