Study On The Jenesis Of Deep Fraction J110 And Block Stability In Baihetan Hydroeletric Power Station Dam

Baihetan hydropower station is in high mountain canyon tract landform. Many hydropower stations in this landform in China have Deep fractions,for example Tongjiezi hydropower station, Daliushu hydropower station, Miaojiaba hydropower station, Jinping primary hydropower station, Pubugou hydropower station, Shenxigou hydropower station, Xiaowan hydropower station, ect. Baihetan hydroeletric power station is without exception. Because of deep cracks in this particular joint, form the boundary slope block, so this has caused deep fractures associated with bulk stability.In the article, the main research of the deep fractures occurrence of geological conditions, Dam left bank of the deep development of fractures distribution, which focuses on the largest and most typical of the deep fractures J110, on this basis, combined with rock mass structure, valley evolution, stress data, geological analysis through the study the genetic mechanism, and then for the block associated with the J110, a detailed description of each border, on the block for geological analysis to calculate the stability of the final procedures using UDEC numerical simulation of two-dimensional stability .In this paper, the following conclutions can be finded:(1)Based on previous research, through field investigation, and further identify the dam site area geology, topography, lithology, geological structure, rock structure, evolution and tectonic stress such as deep valleys evolutionary history of fracture occurrence engineering geological conditions.(2) Dam site left bank there are more deep cracks in the exploration adit CPC 105 exposed points, through field observation and analysis of judgments, a total of 102 deep cracks, from the development and distribution, deformation and mechanical mechanism in the detailed summary of deep cracks law, and J110 in detail. Deep cracks are mainly distributed in the 720m ~ 780m elevation, survey and exploration lineⅠ4 andⅠ5, the most dominant direction N45°W, NE (SW)∠85°~ 90°.(3) Other geological data, and by comparing the results of previous studies, combined with the dam area dating results, study area developed through a wide valley of river valley and the canyon of two stages. The formation of deep cracks in the period from the end of Q3, representing the fourth incised valley, the formation of terracesⅡ(Jinjiang landslide cut exports), tug of war an altitude of about 80m, its geological age of about 39Ka.(4) Deep cracks under the various performance characteristics, its formation is divided into the following stages:1) After tectonic evolution, resulting in NW trending structural cracks;2) Valley incision, lateral unloading, fault zone occurs between spring, NW to the fracture occurred tension;3) Fault zone between rebound occurs, the upper tensile stress generated, leading NE to the crack;4) NE and NW to the deep cracks in deep cracks to complement each other, serrated, further extension of deep cracks.(5) Stress by numerical simulation, extraction of J110 in the incision during each stress value, the path through the stress analysis, combined with the actual dating of the information, obtained the fourth J110 is incised valley formed after this conclusion.(6) From the development of distribution, such as detailed characters change F17, F33, F13, f114, f144, LS337 and other related characteristics of the boundary blocks, and integrated the stability of the parameters are given values. There is a change in the character part, by the weighted average method, more accurately provide the conditions for the stability calculation.(7)The results show that the relevant blocks are in stable states, stability coefficient are1.65,1.52.