石漫滩水库坝基廊道析出物组成特征与成因分析

大坝廊道析出物是坝基水对基岩及混凝土等侵蚀作用的产物,其形成与演变可能对大坝运行安全产生不利影响。石漫滩水库除险加固前其廊道内广泛分布各类析出物,为探明其物质组成并分析来源,对析出物及其附近渗漏水进行了采样分析,对析出物分别采用X射线衍射和荧光光谱分析方法确定其矿物和化学组成,并通过水化学图示和模型计算等方法研究渗漏水的化学组成及演变。结果表明,分布最广泛的白色析出物主要化学组分为CaO和烧失量、矿物组分为方解石,其来自于坝体混凝土中水泥结石的溶解与再沉淀,而部分黑色析出物主要化学组分为MnO,来源于坝基水对基岩中锰质胶结物的化学侵蚀。分析结果结合扬压力等观测资料,可为除险加固工程中坝体及坝基对应补强提供科学依据。

Composition characteristics and genesis analysis of precipitates in dam foundation corridor of Shimantan reservoir

The precipitates in the dam corridor were mostly products of the interaction of groundwater with solid-phase media such as bedrock and concrete.The formation and evolution of the precipitates may have adverse effects on the safe operation of the dam.Before the reinforcement of Shimantan Reservoir,there were varieties of precipitates distributed in the corridor.In order to find out their material composition and analyze their source,we sampled and analyzed the precipitates and their nearby leakage water.X-ray diffraction and fluorescence spectroscopy were used to determine the mineral and chemical composition of the precipitates.Hydrochemical diagram and model calculation were used to study the chemical composition evolution of the leakage water.The results showed that the most widely distributed white precipitate had CaO and loss on ignition as its main chemical components,and calcite as its mineral component.It came from the dissolution and reprecipitation of cement stones in the dam body.Some black precipitates were mainly composed of MnO,and they originated from manganese cement in bedrock.The analysis results together with observation data such as uplift pressure can provide a scientific basis for the seepage reinforcement of the dam.