富钙围岩隧道排水系统结晶物与水环境时空变化规律及结晶路径分析

Analysis of Temporal and Spatial Variation Law of Crystalline Materials and Water Environment and Crystallization Path of the Tunnel Drainage System in Calcium-bearing Surrounding Rocks

通过对7座富钙围岩隧道不同空间和时间下排水结晶物与水环境进行取样检测,分析了结晶矿物、水质和离子浓度的时空变化规律与特征,构建了排水结晶路径模型,明确了结晶钙源和碳源的来源,并给出了防治建议。结果表明,山岭隧道排水系统结晶物在形态上可分为软絮状、粉末块状和硬质结石状,三者形态与硬度各异,生成过程具有连贯性,结晶物形态可指导结晶处治手段的选择;水质参数与离子浓度在空间上具有相同变化规律,初期支护喷射混凝土对水环境的影响最明显,围岩水渗透初期支护喷射混凝土后,水中pH值、溶解性总固体TDS、Ca^(2+)、Na^(+)、K^(+)以及CO_(3)^(2-)浓度值均显著增大,HCO_(3)^(-)浓度值显著降低;Ca^(2+)浓度的增长与降低可揭示初期支护裂损现状及历史发展情况,SO_(4)^(2-)不参与结晶相关反应,其浓度可帮助判断围岩水环境是否出现变化;结晶路径中,结晶物碳源为生物残体、植物根系呼吸作用以及碳酸盐岩的溶解,钙源为富钙围岩的溶解析出和初期支护混凝土水化产物溶解。

By testing the samples collected from the crystalline materials and water environment of 7 tunnels in calcium-bearing surrounding rocks,the temporal and spatial variation law and characteristics of crystalline minerals,water quality and ion concentration have been analyzed,the drainage crystallization path model has been built,the calcium source and carbon source of crystallization have been identified,and the suggestions for prevention and control of the problems are offered.As the results suggest,depending on their forms,the crystalline materials in the drainage system of mountain tunnels can be classified into soft flocculent material,powdery blocky material and hard stony material.The three types of materials have different forms and hardness values and their generative processes are consistent.The forms of crystalline materials are useful in selecting the methods for solving crystallization.The water quality parameters and ion concentration show clearly uniform spatial pattern;the shotcrete initial support has the most obvious impact on the water environment;after water permeating through shotcrete initial support,the pH value,total dissolved solids(TDS),Ca^(2+),Na^(+),K^(+)and CO_(3)^(2-)concentrations in the water increase significantly,while the HCO_(3)^(-)concentration decreases significantly;the increase and decrease of Ca^(2+)concentration will reveal the current condition and history of initial support cracking,SO_(4)^(2-)is not involved in the crystallization related reactions,and its concentration is helpful for determining whether the surrounding rock water environment has changed.In the crystallization path,the carbon source of crystalline materials is from biological residue,respiration of plant root system and dissolution of carbonate,while the calcium source is from calcium dissolution and precipitation of calcium-bearing surrounding rock and the dissolution of hydration products of initial support concrete.