小湾水电站主要工程地质问题评价
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摘要
枢纽区地震地质条件复杂,地震基本烈度高,水库蓄水后有可能产生水库诱发地震。坝址区岩体中高岭土化蚀变现象较普遍,在部分地段成带出现,近EW向和SN向陡倾角破裂结构面发育,且分布有岸坡顺坡中缓倾角节理(河床部位近水平)裂隙。工程区地应力值高,坝基开挖后岩体出现了严重的松弛现象,这些主要地质缺陷对坝基(肩)抗滑和变形稳定问题有一定影响。微风化～新鲜岩体中渗透性具各向异性。地下洞室埋藏深度大,围岩以微风化～新鲜岩体为主,岩体完整,强度高,总体稳定条件较好。崩塌作用普遍,部分地段堆积物厚度较大。卸荷作用强烈,主要发育有陡倾角拉张裂隙和顺坡倾斜的剪切裂隙,边坡稳定条件较差。
Because of the complex seismic geological conditions and high earthquake intensity in the area of control structures, the reservoir-induced earthquake may occur after reservoir impoundment. Kaolinization alteration phenomenon is general in the dam site area and appears in belt in some places and nearly EW and SN direction steep dip angle breakdown structures are developed. There are also some middle-low angle fractures in bank slope (nearly horizontal in riverbed area). The stress in project area is high and the rock relaxation phenomenon is very serious after the excavation of dam foundation rock. These geological defects have certain effects on anti-slide and deformation stabilization of dam foundation or abutment. Permeability in slightly weathered rock and fresh rock is anisotropic. The buried depth of underground caverns is big. The surrounding rock mainly is slightly weathered rock and fresh rock so that the rock is complete with high strength and the overall stability is better. Collapse is common and the thickness of deposits is large in some places. Unloading is very strong and the steep dip angle tensile fractures and straight slope oblique shear fractures are developed. The stability of slope is poor.
Because of the complex seismic geological conditions and high earthquake intensity in the area of control structures, the reservoir-induced earthquake may occur after reservoir impoundment. Kaolinization alteration phenomenon is general in the dam site area and appears in belt in some places and nearly EW and SN direction steep dip angle breakdown structures are developed. There are also some middle-low angle fractures in bank slope (nearly horizontal in riverbed area). The stress in project area is high and the rock relaxation phenomenon is very serious after the excavation of dam foundation rock. These geological defects have certain effects on anti-slide and deformation stabilization of dam foundation or abutment. Permeability in slightly weathered rock and fresh rock is anisotropic. The buried depth of underground caverns is big. The surrounding rock mainly is slightly weathered rock and fresh rock so that the rock is complete with high strength and the overall stability is better. Collapse is common and the thickness of deposits is large in some places. Unloading is very strong and the steep dip angle tensile fractures and straight slope oblique shear fractures are developed. The stability of slope is poor.
引文
[1]中国地震局地质研究所.云南澜沧江小湾水电站工程场地地震安全性评价复核报告[R].北京:中国地震局地质研究所,2009.
[2]昆明勘测设计研究院.云南省澜沧江小湾水电站可行性研究[R].云南:昆明勘测设计研究院,1995.
[3]成都理工大学.澜沧江小湾水电站高边坡稳定性地质—工程分析及支护措施设计优化研究[R].四川:成都理工大学,2007.
[4]中国科学院地质与地球物理研究所.小湾水电站坝基开挖岩体卸荷特性及工程对对策措施研究[R].北京:中国科学院地质与地球物理研究所,2008.
[2]昆明勘测设计研究院.云南省澜沧江小湾水电站可行性研究[R].云南:昆明勘测设计研究院,1995.
[3]成都理工大学.澜沧江小湾水电站高边坡稳定性地质—工程分析及支护措施设计优化研究[R].四川:成都理工大学,2007.
[4]中国科学院地质与地球物理研究所.小湾水电站坝基开挖岩体卸荷特性及工程对对策措施研究[R].北京:中国科学院地质与地球物理研究所,2008.
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