Development and Validation of a Design Method Coupling Block Theory and Three-Dimensional Discontinuous Deformation Analysis

This dissertation, "Development and Validation of a Design Method Coupling Block Theory and Three-dimensional Discontinuous Deformation Analysis" by Ning, Sun, 孫宁, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled Development and Validation of A Design Method Coupling Block Theory and Three-dimensional Discontinuous Deformation Analysis Submitted by Sun Ning for the degree of Doctor of Philosophy at The University of Hong Kong in August 2005 At present, the engineering analysis and design of structures in discontinuous rocks often relies on empirical methods and limit equilibrium analyses. A review of existing limit equilibrium-based methods shows that (1) they do not consider dynamic equilibrium; (2) most cannot handle rotational modes; and (3) none can handle complicated rotational modes such as torsional sliding. To overcome the limitations of existing limit equilibrium analysis methods and to properly analyse the stability of rock blocks, a design method coupling removability analysis of block theory and three-dimensional discontinuous deformation analysis (3D DDA) is developed. The removability analysis is used to identify all removable block types, and a 3D DDA single block analysis is used to determine the mode and stability of each removable block type. In this way, the advantages of both block theory and DDA can be realized. In this dissertation, a 3D DDA single block analysis was developed and extended to allow the calculation of the factor of safety automatically and the consideration of thermal loading and rock anchors. A study was carried out to validate the 3D DDA using physical models and field case histories. Physical models of two different tetrahedral wedges were constructed. The orientation of each wedge was varied systematically and the behaviour of the wedge in each orientation observed and recorded. All the physical modelling cases were then analysed using block theory and 3D DDA. The 3D DDA results agreed well with the physical modelling and block theory results. Furthermore, five field case histories including two wedge failures, a toppling case, an in-situ thermal test, and a rock fall problem were analysed using 3D DDA. By comparing 3D DDA results with the observed behaviour, it was shown that although there were some problems related to handling a large number of blocks in general motion, the present 3D DDA code was a useful method for stability analysis of a single block, which would be sufficient for design coupling with block theory. The validated 3D DDA single block analysis was coupled with block theory's removability analysis. Two program modules, namely the slope module and the tunnel module, were developed for designing slopes and tunnels respectively. A computer program that implements the coupled method was described. Selecting a block size for design and generating a concave block in relation to the tunnel were also discussed. Four case histories, including a road cut slope in the Three Gorges reservoir area, a site formation project involving many cut slopes in rock in Macau, the Elk Creek Tunnel in the USA, and an underground chamber of the Bai-se Hydraulic Power Plant in China, were used to test the coupled method. The applicability and validity of the coupled method were tested by comparing results obtained by the coupled method with those obtained by empirical methods or the limit equilibrium analysis. The results showed that the coupled method could be applied effectively as a design method for rock engineering. DOI: