混凝土坝基防渗帷幕体老化的基本模式及识别指标

摘要

采用综合分析方法,对混凝土坝基防渗帷幕体的老化模式以及识别指标进行了系统的探讨.基于相对防渗效率,把帷幕体老化分为相对稳定型、缓慢变化型以及阶段性变化型3种基本模式;在分析时段内,不同的模式具有不同的防渗效率.用于识别帷幕体老化的指标有3类:第一类为渗流的微观动态要素,包括析钙量、TDS值、pH值、无机质和有机质等,可用于揭示帷幕体的老化机制;第二类为渗流的宏观动态要素,包括扬压力、排水量等,可用于判断帷幕体的老化程度及其基本模式;第三类为数值分析指标,包括饱和指数和渗漏水源比例系数等,可用于量化分析帷幕体的老化过程.3 类指标的识别有助于构建混凝土坝基防渗帷幕体老化评估体系.%The long-term safe operation of a dam can be influenced by the ageing of anti-seepage curtains under its foundation.Based on a synthetic analysis method,basic ageing patterns and some indexes of identification are presented.Three kinds of patterns,including a relatively stable pattern,a slow-weakening pattern and a weakening in stage pattern were classified in terms of the relative anti-seepage efficiency.Each pattern has its unique anti-seepage efficiency during the analysis time.Three types of indexes can be used to identify the ageing.The first type is the micro dynamic elements of seepage,including Ca2+,TDS,pH,inorganic and organic matters,which can be used to reveal the ageing mechanisms.The second one is the macro dynamic elements,including the uplift pressure and flow rate,which can be used to identify the ageing degrees and the basic aging patterns.The third type is the numerical analysis indexes,including the saturation index and ratios of the different seepage sources,which can be used to quantify the ageing process.Evaluation systems for the aging behavior of anti-seepage curtains under a concrete-dam foundation can be constructed based on the 3 types of identification indexes.