长时降雨对片岩边坡的细观损伤机理研究

Study on mechanism of schist slope damage caused by long-term rainfall

研究长时降雨对片岩边坡的细观损伤机理,对阐明片岩边坡经历长时降雨的致灾机制及开展片岩边坡的防护加固具有重要意义.基于低场核磁测试技术,分析了石英云母片岩在不同水岩环境、经历不同作用时间后细观孔隙结构的变化规律,探讨了不同水岩作用对片岩弹性模量和峰值强度的影响,阐明了片岩边坡在长时降雨条件下的细观损伤机理.结果表明:饱和片岩的细观孔隙结构在不同条件的水岩作用下均会发生改变,酸性条件下的长期浸泡促进了片岩原生小孔隙的增长和扩张;片岩孔隙结构(孔径和数量)的改变与溶解到液体中的矿物元素的含量变化具有明显的相关性;酸性溶液入渗与片岩中的矿物成分反应后最终将变为中性,而无论是哪种性质的溶液,对片岩的损伤都是从与片岩中矿物颗粒反应和溶解颗粒间胶结物质开始的,这是早期裂隙形成的基础,与片岩自身的各向异性无关;长时浸泡后孔隙结构的改变,弱化了岩石矿物结构的承载能力,进而影响片岩的力学性能(弹性模量、峰值强度等).

It is of great significance to study the damage mechanism of schist slopes caused by long-term rainfall and carry out their protection and reinforcement.Based on the low field nuclear magnetic testing technology,the change pattern of the micro pore structure of quartz mica schist in different water rock environments and after different action time is analyzed and the influence of different water rock interaction on the elastic modulus and the peak strength of the schist is discussed.The results show that the micro pore structure of the saturated schist will change under water rock interaction.Compared with the neutral condition,the long-term immersion under the acid condition promotes the growth and expansion of the original small pores of the schist.The change of the pore structure of the schist(pore size and number)is obviously related to the change of the content of mineral elements dissolved in the liquid.After the acid solution infiltrates and reacts with the mineral elements in the schist,it will eventually become neutral.No matter what kind of solution it is,the damage to the schist starts from the reaction with mineral particles in the schist and the dissolution of cemented material between particles,which is the basis of the formation of the early fracture and has nothing to do with the anisotropy of the schist itself.The change of pore structure after long-term immersion weakens the bearing capacity of rock mineral structure,hence affects the mechanical properties of schist(modulus of elasticity,peak strength,etc.)