中文摘要：

帷幕体的修建是为了对坝基进行加固和防渗,但在蓄水条件下,坝基帷幕体遭受长期的高压渗流、溶蚀等作用,坝基帷幕防渗作用衰减以致失效,从而引起坝基渗流量增加和扬压力增高。依据地球化学热力学的基本理论,通过分析坝基地下水微观动态,定量化解析幕后地下水溶液与某种矿物之间的反应状态,采用了基于化学热力学模型的FORTRAN程序,从一个侧面来反映坝基帷幕体防渗效果及其耐久性。结合某工程实例,建立2001-2010年的时间序列模型,计算出的方解石饱和指数由2.03变为0.26,揭示出某坝10坝段处坝基帷幕体的防渗性能及其耐久性发生了衰减,且具有阶段性变化的特点,2001-2004年间与2006-2008年间坝基地下水的微观动态处于相对稳定的时期（缓变）;2005年间与2009-2010年间处于突变时期（陡变）。揭示出该坝段坝基帷幕体的防渗性能出现了局部的衰减,其结果与地下水宏观动态反映出的规律较一致,证明该方法在一个侧面能够反映出帷幕体的防渗性能和耐久性的变化特征。

英文摘要：

The curtain is built up for stability and anti-seepage of dam foundation.By long-term water pressure and erosion,the seepage and uplift pressure under dam foundation increase gradually,causing its efficiency decay.Although the statistical model based on the monitoring data of groundwater macroscopic regime is often used to analyze,it has a lot of influential factors to calculate a finite period of time.The interaction between groundwater and some mineral,which reflects the mechanism of curtain decay,is modeled by a FORTRAN program according to the chemic-thermodynamics theory.A model is built up to analyze the anti-seepage efficiency of dam curtain;and the result shows that the 10th dam section has its efficiency decayed.The Saturation Index（SI） of section 10 kept the tendency of decreasing with time from 2001 to 2010.Calculated calcite saturation index changed from 2.03 to 0.26,It revealed the durability of curtain of dam section 10 was weakened.The microcosmic of dam section 10 kept a certain relationship with reservoir water level from 2001 to 2004 and from 2006~2008.The microcosmic of dam section 10 kept close relationship with reservoir water level at 2005 and from 2009 to 2010.The curtain is to be weakened locally.It is proved that the method can reflect the changes of the effect of curtain and its durability.