干湿循环作用下深部砂岩物理力学性能变化研究

Study on Changes of Physical and Mechanical Properties of Deep Sandstone Under Dry-Wet Circulation

为研究深部开采过程中地下水对深部岩体的影响与危害,以确保深部工程的安全稳定,以淮南张集矿区内的砂岩为试验对象,研究其在酸性(pH=3)、中性(pH=7)、碱性(pH=11)溶液中经历多次干湿循环处理后的物理力学性能的变化,并对砂岩材料内部损伤及劣化机理进行了综合分析。结果表明:随着干湿循环次数的增加,砂岩试样质量损失逐渐增大,致密程度有所减小,且峰值应力、弹性模量、纵波波速均大幅下滑;砂岩试样出现不同程度的损伤劣化,但峰值应变的增大表明砂岩试样被软化,脆性得到良好改善;同一循环次数下,酸碱性溶液对砂岩试样的破坏更为显著,且酸碱性溶液侵蚀与干湿循环作用的耦合促进了砂岩试样损伤劣化的加剧和扩大。

In order to study the influence and harm of underground water on deep rock mass during deep mining and to ensure the safety and stability of deep engineering, the sandstone in Zhangji mining area in Huainan was taken as the test object to study the change of physical and mechanical properties of sandstone after repeated dry-wet circulation in acidic(pH=3), neutral(pH=7) and alkaline(pH=11) solutions, and the internal damage and deterioration mechanism of sandstone materials were comprehensively analyzed. The results show that with the increase of dry-wet circulation, the mass loss of sandstone samples gradually increases, the compactness decreases, and the peak stress, elastic modulus, and longitudinal wave velocity significantly decrease. The sandstone samples present different degrees of damage and deterioration, but the increase of peak strain shows that the sandstone samples are softened and the brittleness is improved. Under the same number of circulations, the damage of acid-base solution to sandstone samples is more significant, and the coupling of acid-base solution erosion and dry-wet circulation promotes the aggravation and expansion of the damage and deterioration of sandstone samples.