Research On Theory And Application Of 3D Refined Modelling Of Rock Structure And Surface-block Analysis For Hydropower Project

Rock structure is one of main factors influencing stability problem of dam foundation, dam shoulder, underground structures and slope engineering. In large-scale hydroelectric project, underground water diversion and power generation system is mostly laid deeply into solid rock mass with high geo-stress, and complicate geological environment surrounding the underground structures is made up of regional geological structures, such as fault, weak intercalated layers, and interlayer shear zone, and fissure structures stochastically developing inside rock mass. These geological discontinuities and excavation face of underground structures intersect with each other, and many engineering blocks are cut off. Instability of these blocks will lead to destruction of cave surrounding rock, and then influence project safety. Therefore, accurate analysis and prediction for block information surrounding underground structures, including position, geometrical morphology and relationship with structures, is one of key problems during designing and construction of large span underground cavern. Base on analysis of geological data for hydroelectric project and combing 3D geological modeling with 3D network simulation of discontinuity, theory and method of 3D refined geological modeling for hydroelectric project was present, and, with the help of this model, rapid identification for surface-block of underground structures was studied. The main contents and achievements are as follows:1. Based on determinate geological data and according to geological structures characteristic, method of 3D geological modeling is introduced for hydroelectric project. Hybrid data structure of engineering geology and NURBS construction technology of geological structure for hydroelectric project are studied, and relevant geometry modeling methods are present for different kind of geological object. Then, 3D geological model for hydroelectric project is realized.2. According to fissure development characteristic, randomness, grouping and regionalization, the simulation technology of 3D discontinuity network is introduced to reconstruct stochastic fissure in engineering region. To improve the reality of simulation, the method of dynamic verification for simulated fissure, based on fissure data from field measurement, is researched, and then it is ensured that simulation result will keep the same as field condition in sampling area. With the help of 3D geological structure model, fissure surfaces are dynamically simulated, and 3D refined geological model is rebuilt, which finely descript the complicate geological environment in engineering region.3. Based on 3D refined geological model, the identification method of surface-block in underground structures is studied. Concept of surface-block is presented, and its definition is made. Three theorems, sealability, completeness and uniqueness, are put forward to realize identification of surface-block. To improve identification efficiency, geological structure surface network is optimized with undirected graph, and identification functions of restrict surface block and free surface block are designed.4. The above theories and methods have been applied to a hydroelectric project. 3D geological model and 3D refined geological model are reconstructed, then, identification of surface blocks surrounding underground structures is done, and geometry of these blocks are analyzed, which supplies many useful qualitative and quantitative data for the following stability analysis and surrounding rock support.