| Huang Deng proposed hydroelectric station is located in the territory of Lanping County in Yunnan province, the normal water level of the reservoir is 1619m, the installed capacity is 1900MW. The beginning style of the proposed dam is the gravity dam, and its maximum height is 202m. The intake slope of the dam site area has the characteristics of large-scale excavation, the largest excavation height is 305m, the level of the excavation depth is 40 ~ 80m. At the same time by the steep outside surface of the structure, geological conditions in different parts of the terrain,and slope geological structure has different characteristics, potential deformation model is complex and diverse, post-excavation work may be faced with many geological problems. Based on this, this paper is based on the intake high-slope of Huang Deng hydroelectric station of the Lancang River for the study. By geological analysis, limit equilibrium methods, finite difference method (FLAC) and based block theory evaluation method, and by in-depth systematic study on the deformation response of the overall and local of the intake high-slope resulting from excavation, the prediction of their stability was evaluated. At the same time for different parts of the stress-deformation field had the difference characteristics, the corresponding support treatment recommendations was made. Through a comprehensive system of analysis and assessment, this paper made the following findings and basic understanding:(1) Through the field investigation and indoor data collation and statistics analysis, preliminarily study the rock mass structure of the intake slope in the dam site, including the geological features of different structural surface, especially the geological characteristics and effect of steep structural surface to the slope deformation, Established a structural model of rock mass slope. By identifying the geometric characteristics and geological characteristics of the structure surface, and then fastly qualitatively classified the slope rock mass quality in the field.(2) Using PHASE numerical simulation software to analyze the current stress field of valley in the area of the intake slope, and thus an accurate understanding of the current dynamic environment of the high rock slope was made. According to the slope deformation and fracture characteristics in the current exploration phase, and according to the phenomenon with the deformation and fracture of the natural slope, combined with the structural features of the rock slope, the main deformation model of the intake slope can be divided into two category four subgroups. The intake slope mainly occurred flat slope sliding failure and partial wedge block sliding failure.(3) Using FLAC finite difference method in the overall stress-deformation field simulation, and then analyze the stress deformation characteristics response to the excavation of the intake slope. The results showed that: after excavation, the rock mass to the empty direction in unloading rebound, in the shallow areas of the excavation site, the local tensile stress concentration occurs, the size of tensile stress is 0.5~2.00Mpa; and the slope maximum displacement after excavation is 7.70cm, the maximum displacement occurs in the surface and mezzanine area, these areas may occur deformation and failure, and should strengthen support measures.(4) Using the SLIDE limit equilibrium method software, analyze and forecast the stability of the intake slope after excavation, further analysis and prediction to the potential damage of its slide was made. The results showed that: after excavation, its stability works better in the natural condition, the stability factor of the potential slip surface is greater than 1.40. In the rain or under earthquake it is greater than 1.2, the stability of potential sliding body is good.(5) Using the Block-based theory of SASW procedure to analyze the stability of the wedge-shaped blocks in the local area on the slope. In this paper, a series of semi-deterministic and random blocks of different shape and size and its stability in different conditions was analyzed. The results showed that: the block stability is better, blasting and rainfall to the stability of the block is sensitive, induced the possibility of instability. And the construction should be promptly taken to anchor reinforcement.Using the FLAC finite difference method to study the stress and large deformation problems of the overall intake slope, identify the largest part of the deformation on the slope. And using the SLIDE Software and block theory of SASW procedure to analyze and predict the potential damage on the sliding slope and the block failure , obtained the reliable indicator of the stability. To be able to take timely and effective construction support measures for slope reinforcement, to prevent the continued development of rock mass deformation fracture occurred. the most effective control measures to such slope is taken spray anchor timely, and anchor reinforcement in the foot of the slope, faultage and mezzanine sites during the excavation process. |
