石膏质岩水化特性及矿物含量确定方法研究

A study of the hydration characteristics and determination method of mineral content of gypsum rock

硬石膏和石膏的膨胀性和腐蚀性是石膏质岩隧道工程主要致害因素,查明矿物成分、水化特性、硬石膏和石膏含量是评价石膏质岩工程危害的基础,但目前尚缺乏快速简便的石膏质含量确定方法。通过测定硬石膏岩水化过程中的波速及水化深度,分析了石膏质岩的水化特性;通过对硬石膏、石膏、方解石、白云石不同配比混合物的热重分析,提出了快速测定石膏质岩矿物含量的热重分析法。结果表明:(1)石膏质岩矿物成分的鉴别建议采用热分析、X射线衍射、红外光谱等方法相互印证;(2)硬石膏岩水化缓慢,标准尺寸试件的硬石膏岩完全水化为石膏岩约需2 a;(3)完整硬石膏岩在纯净水环境下水化速率约3 mm/a,若地下水环境富含SO_(4)^(2-),硬石膏岩水化速率将增加。文章建立的石膏质岩矿物含量确定方法可以快速确定硬石膏和石膏的质量分数,研究成果可为分析石膏质岩的工程危害提供参考。

Expansibility and corrosivity of anhydrite and gypsum are the main disease-causing factors in gypsum rock tunnel engineering.Investigation of the mineral compositions,hydration characteristics,and contents of anhydrite and gypsum is the basis for evaluating the engineering hazard of gypsum rock.However,there is a lack of quick and simple method to determine the content of gypsum.By measuring the wave velocity and hydration depth in the hydration process of anhydrite rocks,the hydration characteristics of gypsum rocks are analyzed.Through the thermogravimetric analysis of anhydrite,gypsum,calcite and dolomite mixtures with different proportions,a thermogravimetric analysis method for rapid determination of mineral content of gypsum rocks is proposed.The results show that(1)thermal analysis,X-ray diffraction and infrared spectroscopy are recommended for the identification of mineral components of gypsum rocks.(2)Hydration of anhydrite rocks is slow,and it takes about 2 years for anhydrite rocks of the standard size specimen to be fully hydrated into gypsum rocks.(3)The hydration rate of intact anhydrite in the pure water environment is about 3 mm/a.If the groundwater environment is rich in SO_(4)^(2-),the hydration rate of anhydrite will increase.The established method for determining the mineral content of gypsum rocks can quickly determine the contents of anhydrite and gypsum.The study results provide a reference for analyzing the engineering hazards of gypsum rocks.