大坝坝基岩石性状变化的评价

Evaluation of Rock Characteristic Change of Dam Foundation

大坝建成蓄水 ,坝址自然环境发生剧变 ,有利于库水中有机质的富集 ,致使下层库水弱酸性化和含侵蚀CO2 .库水在向坝基运移过程中 ,与坝基岩石间产生物理化学作用 .钾、钠、硅、铝等元素是组成岩石的基本成分 ,它们在坝基水中的大量迁移是评价坝基软岩性状变化 (软化、泥化 )的重要依据 .少数坝基胶状析出物化学成分中 ,SiO2 和Al2 O3 含量高达 5 0 %以上 ,水中SiO2 - 3 含量也丰富 ,说明坝基局部地段软岩性状发生了变化 .

After completion of a dam, the natural environmental change at the dam site helps the enrichment of organic materials in the reservoir, resulting in the generation of erosive CO 2 in the lower layer of the water. In the transferring process of the erosive water toward the dam foundation, physiochemical reaction occurs between the water and the rock of the dam foundation. The elements of potassium, sodium, silicon, and aluminum are the basic components of the rock, the transference quantity of which in dam foundation water is an important basis for the evaluation of changes (softening and argillazation) of the soft rock in the dam foundation. The contents of SiO 2 and Al 2O 3 are more than 50% in some colloidal sludge from the dam foundation and the content of SiO 3 2- in water is abundant, indicating the characteristic change of the soft rock in some sections of the dam foundation.