【摘要】 依据气体化学组分和同位素组成分析,结合水文地质资料,分析了缅甸其培电站坝址钻孔随承压水逸出的气体、平硐揭露的断裂带气体的地球化学特征,并探讨其形成和对工程的影响。研究结果表明:坝址断裂带气体有CO2型和N2型2类,以CO2为主的气体中CO2的摩尔分数为89.37%～98.83%,N2的摩尔分数为0.7%～10.42%;含有微量的甲烷,摩尔分数为0.2%～0.47%。CO2的δ13 CV-PDB=-4.947‰～-5.387‰,δ18 OV-PDB=3.364‰～3.613‰,CO2为深部幔源无机成因。δ15 N值在-0.082‰～7.263‰之间,变化范围较大,有浅部生物成因气体混入。CO2气体形成于深部,沿断裂带运移,在浅部与承压水混合,主要在河床逸出。深部起源的CO2气体是恩梅开江断裂在坝址的地质活动性的显示。河床是气体逸出的主要部位,气体产出量大,对坝址工程处置有较大影响。更多还原

【Abstract】 According to the analysis of the chemical and isotopic compositions of the gas and combined with the hydrogeological data,this paper analyses the geochemical characteristics of the escaping gas from the drill holes and adits of the fault zone at Chipwi dam site in Burma and explores the formation of the gas and its impact on the project.The result reveals that the gas consists of two types,that is,CO2 and N2.The mole fraction of CO2 is 89.37%~98.83% and that of N2 is 0.7%~10.42%,but there is 0.2%~0.47% methane.CO2 has δ13CV-PDB values ranging from-4.947‰ to 5.387‰ and δ18OV-PDB from 3.364‰ to 3.613‰,showing that the CO2 belongs to deep mantle sourced inorganic origin.δ15N ranges from-0.082‰ to 7.263‰ and changes greatly,mixing with a lot of shallow biogenic gas.CO2 gas forms in the deep,migrates along the fault zone,mixes with confined water in shallow and mainly escapes from the riverbed.The deep origin of CO2 is an evidence of the geological activity of the Nmai Hka fault zone at the dam site.The gases are mainly emitted from the riverbed and their output large,having a great impact on the dam site project disposal.更多还原