石膏岩溶蚀与强度特性试验研究

石膏岩在工程中使用广泛,其具有特殊的物理化学性质,常引发工程问题,因此研究石膏岩的溶蚀特性以及溶蚀前后强度、塑性、脆性等性质变化显得尤为重要。通过室内溶蚀试验分析其溶蚀机理,利用电镜扫描观察其微观结构,分析强度劣化机理,并通过单轴压缩试验,研究石膏岩在不同溶液条件下的软化性质。结果表明,不同溶液对石膏岩的影响不同。以石膏岩浸泡在纯水中为参照,NaCl溶液促进石膏岩的溶蚀量,使试样的强度降低,为纯水溶蚀后试样强度的40%,塑性变强,脆性减弱;冰醋酸溶液减少石膏岩的溶蚀量,强度少许增加,塑性变弱,脆性变强;氢氧化钠溶液可与石膏岩发生反应生成氢氧化钙,因此在前期可促进石膏岩的溶蚀,后期生成较多的氢氧化钙络合物附着在岩样表面阻止石膏岩继续溶蚀并使其强度变大、塑性变强。微观电镜图片显示,不同溶液对石膏岩的溶蚀程度以氯化钠溶液最为严重,其次分别为纯水、冰醋酸溶液、氢氧化钠溶液。单轴压缩试验时声发射活动发生次数与溶蚀量相一致。

Experimental Study on Dissolution and Strength Characteristics of Gypsum Rock

Gypsum rock is widely used in engineering and has special physical and chemical properties, which often cause engineering problems. Therefore, it is especially important to study the dissolution characteristics of gypsum rock and its properties such as strength, plasticity and brittleness before and after dissolution. In this paper, the dissolution mechanism is analyzed by indoor dissolution test. The microstructure is observed by electron microscopy, the strength deterioration mechanism is analyzed, and the softening properties of gypsum rock under different solution conditions are studied by uniaxial compression test. The results show that different solutions have different effects on gypsum rock. The gypsum rock is immersed in pure water as reference. The NaCl solution promotes the dissolution of gypsum rock. The strength is greatly reduced, which is about one third of the strength of pure water. The plasticity becomes stronger and the brittleness is weakened; The glacial acetic acid solution reduces the amount of dissolution of gypsum rock, the strength increases slightly, the plasticity becomes weak, and the brittleness becomes stronger; the sodium hydroxide solution can react with the gypsum rock to form calcium hydroxide, so in the early stage It can promote the dissolution of gypsum rock, and the later formation of more calcium hydroxide complex attached to the surface of the rock sample prevents the gypsum rock from being dissolved and the strength becomes larger and the plasticity becomes stronger. Microscopic electron micrographs show that the dissolution of gypsum rock by different solutions is most serious with sodium chloride solution, followed by pure water, glacial acetic acid solution and sodium hydroxide solution. The intensity of the acoustic emission activity is consistent with the amount of erosion.