青藏高原东缘水库绕坝基渗流化学溶蚀研究
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摘要
研究了青藏高原东缘某大坝基础遭受渗流场与化学场破坏的过程。通过氯离子示踪、温度电导示踪以及人工示踪方法,确定混凝土防渗墙中存在缺陷,库水通过非全封闭式防渗墙绕坝基渗漏,渗水通过坝后区的反滤层排泄;酸溶解试验和X射线荧光分析证明,坝后区地表的白色颗粒物主要是CaCO_3;结合化学反应过程,确认析出物来自于防渗墙中的水泥,渗漏水中的CO_2与水泥中的Ca(OH)_2发生反应生成可溶性Ca(HCO_3)_2,然后被渗漏水带到地表,并在常温下分解形成CaCO_3。通过地表水中CO_2含量的测试分析发现,参与水岩反应的CO_2具有除大气降水之外的其他来源。结合地质构造推断来自深部碳库中的CO_2通过断裂带进入到了地下水与库水中,并参与了水岩反应,对大坝的侵蚀速度大幅度增加。研究表明深部CO_2进入地下水并参与渗流过程,对大坝及水工建筑物的化学侵蚀作用将大幅度增强。
The foundation failure of a dam on the eastern margin of the Tibetan Plateau during seepage and chemical processes is studied. By using Cl-tracing, temperature-conductivity tracing and artificial tracing techniques, it is determined that there is leakage through the non-closed concrete cut-off wall, where the reservoir water leaks through the dam foundation, and excretes through the filter layer after the dam area. The acid dissolution experiment and X-ray fluorescence analysis show that the precipitated white particles on the surface after the dam are mainly composited of CaCO_3. Combined with the chemical reaction process. It is confirmed that the precipitation comes from the cement of cut-off wall. The CO_2 dissolved in the leakage water reacting with Ca(OH)_2 in the cement can generate soluble Ca(HCO_3)_2, which is taken to the surface by the leakage water and decomposed to CaCO_3 at normal temperature. Through the measurement and analysis of CO_2 content in surface water, it is found that CO_2 in the water-rock reaction has other sources except atmospheric precipitation. Considering the local geologic structure, it is inferred that CO_2 mainly from the deep carbon pool enters the groundwater and reservoir water through the fault zones, and participates in the water-rock reaction. This results in a faster erosion of the dam. The chemical erosion of the dam and hydraulic structures will be greatly enhanced if the deep CO_2 enters the groundwater and participates in the seepage process.
The foundation failure of a dam on the eastern margin of the Tibetan Plateau during seepage and chemical processes is studied. By using Cl-tracing, temperature-conductivity tracing and artificial tracing techniques, it is determined that there is leakage through the non-closed concrete cut-off wall, where the reservoir water leaks through the dam foundation, and excretes through the filter layer after the dam area. The acid dissolution experiment and X-ray fluorescence analysis show that the precipitated white particles on the surface after the dam are mainly composited of CaCO_3. Combined with the chemical reaction process. It is confirmed that the precipitation comes from the cement of cut-off wall. The CO_2 dissolved in the leakage water reacting with Ca(OH)_2 in the cement can generate soluble Ca(HCO_3)_2, which is taken to the surface by the leakage water and decomposed to CaCO_3 at normal temperature. Through the measurement and analysis of CO_2 content in surface water, it is found that CO_2 in the water-rock reaction has other sources except atmospheric precipitation. Considering the local geologic structure, it is inferred that CO_2 mainly from the deep carbon pool enters the groundwater and reservoir water through the fault zones, and participates in the water-rock reaction. This results in a faster erosion of the dam. The chemical erosion of the dam and hydraulic structures will be greatly enhanced if the deep CO_2 enters the groundwater and participates in the seepage process.
引文
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[2]周创兵,陈益峰,姜清辉,等.论岩体多场广义耦合及其工程应用[J].岩石力学与工程学报,2008,27(7):1329-1340.(ZHOU Chuang-bing,CHEN Yi-feng,JIANG Qing-hui,et al.On generalized multi-field coupling for fractured rock masses and its applications to rock engineering[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(7):1329-1340.(in Chinese))
[3]王媛.单裂隙面渗流与应力的耦合特性[J].岩石力学与工程学报,2002,21(1):3-87.(WANG Yuan.Coupling Characteristic of stress and fluid flow within a single fracture[J].Chinese Journal of Rock Mechanics and Engineering,2002,21(1):83-87.(in Chinese))
[4]李旭春,张国立.环境水对回龙山水电站水工建筑物侵蚀的研究[J].海河水利,2002(3):37-38.(LI Xu-chun,ZHANG Guo-li.Environmental Water Erosion of hydraulic structures in Huilongshan hydropower station[J].Haihe Water Resources,2002(3):37-38.(in Chinese))
[5]林和振.大坝环境水潜蚀作用与防治对策[J].吉林水利,2006(4):17-18.(LIN He-zheng.Erosion Action by environment water to the dam and its countermeasures of prevention and control[J].Jilin Water Resources,2006(4):17-18.(in Chinese))
[6]宋汉周,施希京.大坝坝址析出物及其对岩体渗透稳定性的影响[J].岩土工程学报,1997,19(5):16-21.(SONGHan-zhou,SHI Xi-jing.Precipitation at dam site and its influence on rock mass permeability stability[J].Chinese Journal of Geotechnical Engineering,1997,19(5):16-21.(in Chinese))
[7]宋汉周,朱旭芬,彭鹏,等.坝址渗水析出物及其潜在影响研究[J].水利学报,2011,39(4):454-460.(SONGHan-zhou,ZHU Xu-feng,PENG Peng,et al.Study on seepage colloidal educts of dam and its potential effects[J].Journal of Hydraulic Engineering,2011,39(4):454-460.(in Chinese))
[8]王涛,陈建生,王婷,等.熵权-集对分析模型探测堤坝渗漏[J].岩土工程学报,2014,36(11):2136-2143.(WANG Tao,CHEN Jian-sheng,WANG Ting,et al.Entropy weight-set pair analysis(SPA)for the dam leakage detetion[J].Chinese Journal of Geotechnical Engineering,2014,36(11):2136-2143.(in Chinese))
[9]WANG T,CHEN J S,WANG T,et al.Entropy weight-set pair analysis based on tracer techniques for dam leakage investigation[J].Natural Hazards,2015,76(2):747-767.
[10]DONG H,CHEN J,LI X.Delineation of leakage pathways in an earth and rockfill dam using multi-tracer tests[J].Engineering Geology,2016,212:136-145.
[11]陈建生,董海洲.堤坝渗漏探测示踪新理论与技术研究[M].北京:科学出版社,2007:51-205.(CHEN Jian-sheng,DONG Hai-zhou.Dam leakage detecting tracer new theory and technology research[M].Beijing:Science Press,2007:51-205.(in Chinese))
[12]杨虎,蒋林华,张研,等.基于溶蚀过程的混凝土化学损伤研究综述[J].水利水电科技进展,2011,31(1):83-89.(YANG Hu,JIANG Lin-hua,ZHANG Yan,et al.Summary of researches on chemical damage of concrete based on leaching process[J].Advances in Science and Technology of Water Resources,2011,31(1):83-89.(in Chinese))
[13]张祖莲,朱汉明.浅谈啤酒酿造用水中的二氧化碳[J].啤酒科技,2008(3):18-20.(ZHANG Zu-lian,ZHU Han-ming.Discussion on carbon dioxide in beer brewing water[J].Beer Science and Technology,2008(3):18-20.(in Chinese))
[14]陈俊,王鹤年.地球化学[M].北京:科学出版社,2004:185-186.(CHEN Jun,WANG He-nian.Geochemistry[M].Beijing:Science Press,2004:185-186.(in Chinese))
[15]赵小杰,赵同谦,郑华,等.水库温室气体排放及其影响因素[J].环境科学,2008,29(8):2377-2384.(ZHAOXiao-jie,ZHAO Tong-qian,ZHENG Hua,et al.Greenhouse gas emission from reservoir and its influence factors[J].Environmental Science,2008,29(8):2377-2384.(in Chinese))
[16]石慧馨.中国碳酸水出露带分布特征简介[J].地震地质,1979,1(2):88-95.(SHI Hui-xin.A note on carbon-dioxide discharging zones and their seismicities in China[J].Seismology and Geology,1979,1(2):88-95.(in Chinese))
[17]许志琴,杨经绥,侯增谦,等.青藏高原大陆动力学研究若干进展[J].中国地质,2016(1):1-42.(XU Zhi-qing,YANG Jing-sui,HOU Zeng-qian,et al.The progress in the study of continental dynamics of the Tibetan Plateau[J].Geology in China,2016(1):1-42.(in Chinese))
[18]杨贤和,田玉苹.康定温泉逸出气百分含量突跳与地震对应关系[J].四川地震,2001,1(1):42-44.(YANG Xian-he,TIAN Yu-ping.Relative relationship between earthquakes and sudden changes of air content of the hot spring in Kanding[J].Earthquake Research in Sichuan,2001,1(1):42-44.(in Chinese))
[19]朴龙泽,赵淑明.丰满大坝渗水对混凝土的溶蚀分析[J].水利水电技术,2000,31(10):34-36.(PIAO Long-ze,ZHAO Shu-ming.Corrosion analysis of concrete by water seepage in Plump dam[J].Water Resources and Hydropower Engineering,2000,31(10):34-36.(in Chinese))