白云岩隧道排水路径结晶趋势变化及影响分析

Crystallization Trend Change and Influencing Factors of Tunnel Drainage Path in Dolomite

为明确公路隧道排水路径中结晶物与水环境变化特征,分析结晶趋势路径变化及趋势计算方法的适用性,以白云岩隧道排水结晶病害为背景,以排水路径“围岩水—初期支护水—排水管水”为分析脉络,对比分析排水路径中结晶矿物含量、8大离子质量浓度及水质参数的变化特征,利用Davis-Stiff饱和指数法和方解石饱和指数法,计算并阐明排水路径中结晶趋势的变化规律,并对上述方法的适用性与主要水环境参数对结晶趋势的影响进行分析。研究结果表明:1)白云岩隧道排水结晶矿物为方解石,排水路径中方解石含量(质量分数)急剧增长,在围岩内仅占0.6%,在初期支护喷射混凝内占比增至15%,在排水管结晶物中剧增至100%。2)排水路径中初期支护喷射混凝土对水离子质量浓度影响最为显著,围岩水经过喷射混凝土后,Ca^(2+)质量浓度大幅增高,pH值显著增大,HCO_(3)^(-)质量浓度大幅降低,CO_(3)^(2-)质量浓度显著增大,盐度SAL、溶解性总固体TDS和电导率Cond始终呈线性增长趋势。3)排水路径中结晶趋势呈先增大后稳定的变化规律,Ca^(2+)和CO_(3)^(2-)质量浓度对结晶趋势的影响大于温度t与pH值。4)方解石饱和指数法计算的结晶趋势结果与实际情况一致,其适用于白云岩隧道水环境结晶趋势分析。

To investigate the characteristics of crystalline material and the effect of water environment on the drainage path of highway tunnels and analyze the applicability of crystallization change and trend calculation method,a case study is conducted on drainage crystallization disease of tunnels in dolomites.The drainage path of"surrounding rock water-initial branch water-drainage pipe water"is regarded as the analysis context to comparatively analyze the variation characteristics of crystalline mineral content,concentrations of the Eight Ions of water,and water environment parameters in the drainage path.In addition,the variation law of crystallization trend in the drainage path is calculated and clarified using the Davis-Stiff saturation index method and calcite saturation index method.Moreover,the applicability of the recommended methods and the influence of main water environment parameters on the crystallization trend are analyzed.The results reveal the following:(1)The tunnels exhibit calcite drainage crystallization,and the content of calcite in the drainage path increases sharply.The calcites account for 0.6%and 15%of the surrounding rock and primary support shotcrete,respectively.(2)The primary support shotcrete significantly affect the water environment parameters in the drainage path.It dramatically increases the concentrations of Ca^(2+)ions,CO_(3)^(2-) ions,and pH value and sharply decreases the concentration of HCO_(3)^(-) ions.Salinity,total dissolved solids,and conductivity exhibit an increasing trend.(3)The drainage path initially exhibits an increasing crystallization trend and then stabilizes.The influence of Ca^(2+)ion and CO_(3)^(2-) ion concentrations on the saturation trend is greater than that of the temperature t and pH value.(4)The calculation results of the crystallization trend of the calcite saturation index method are consistent with the actual situation.Thus,the findings show that the proposed method is suitable for analyzing the crystallization trend of the tunnel water environment in dolomite.