粉砂质泥岩的强度衰减与环境效应试验研究

EXPERIMENTAL STUDY ON SILTY MUDSTONE STRENGTH ATTENUATION AND ENVIRONMENTAL EFFECT

在不同质量百分比(1%,5%及10%)的2种酸(H2SO4,HNO3)溶液和1种碱(NaOH)溶液、1种有机质(腐植酸钠)溶液、1种无机盐(KCl)溶液和自来水中,对粉砂质泥岩的水–岩作用进行静态长时(120d)加速浸泡试验模拟,并测定其单轴抗压强度、微观结构、氧化物成分,研究岩样单轴抗压强度随时间对酸、碱、有机质和盐的敏感性和衰减机制。研究结果表明,在静水环境下,岩样强度衰减、腐蚀速率与H+浓度、酸根离子、无机盐浓度及浸泡时间成非线性关系,岩样的强度变化正比于岩样的质量变化;认为在水–岩作用过程中,溶解与沉淀、氧化与还原作用同时发生,共同影响岩样强度的衰减规律;水–岩作用的不同时期,导致岩样强度衰减的主要因素是不同的;在化学风化作用下,岩样的强度与铁离子、钙离子等二价离子的变化密切相关。

Aimed to understand how rocks get deteriorated under different conditions, accelerated simulations of water-rock interaction for silty mudstone have been carried out continuously in static water surroundings with two acid solutions（H2SO4 and HNO3）, a sodium hydroxide solution（NaOH）, a sodium humate solution, and a inorganic saltsolution（KC1） with different mass contents（l%, 5% and 10%） for 120 days. The unconfined compressive strength（UCS）, microscopic characteristic changes, oxides component changes of silty mudstone are monitored during the simulation. And then the sensitivities of the UCS to solutions types and deterioration mechanism are analyzed. The results show that strength attenuation and eroded rate will nonlinearly increase with the concentration of H^＋, acid atom, concentration of inorganic salt and soak period; the change of UCS is direct proportional to the change of rock mass. It is verified that dissolution and precipitation, oxidation and reduction present simultaneously in the course of water-rock interaction; and the rule of strength attenuation is effected by all of them; the main reason of strength attenuation is different in different water-rock interaction stages. UCS is closely related to the change of divalent iron ion and calcium ion under chemical weathering. Water quality will be deteriorated because of the much metal stripping during water-rock interaction. However, the results show that long-term water-rock interaction also has its beneficial aspect to the rock UCS; and the environmental effects of water-rock interaction have dual characters.