花岗岩在化学溶蚀和冻融循环后的力学性能试验研究

通过研究花岗岩在不同化学溶液（水、NaOH溶液和HNO₃溶液）中浸泡并冻融循环后的力学性能,分析了花岗岩在不同化学溶液中溶蚀及经历不同冻融循环次数后,在单轴压缩作用下基本力学性能的变化规律;从微观力学和化学机理出发,探讨了化学溶蚀和冻融循环对花岗岩的损伤机理;通过定义损伤变量,定量分析了花岗岩的损伤程度。试验结果表明,在水、NaOH和HNO₃溶液中,随着冻融循环次数的增加,花岗岩的相对杨氏模量呈指数函数减小,峰值应力损失率呈幂函数增加;轴向峰值应变按Guass函数变化。随着冻融循环次数的增加,HNO₃溶液中的花岗岩初期损伤劣化较大,后期损伤劣化较小,而NaOH溶液中的花岗岩初期损伤劣化较小,后期损伤劣化较大。岩石冻融损伤的过程本质上是温度产生的应力,使岩石损伤劣化的过程;同时化学溶蚀对岩石产生化学损伤作用,与冻融损伤相互促进,共同影响岩石的损伤劣化。

Experimental research on mechanical properties of granite in chemical dissolution under freeze-thaw cycles

The variation of mechanical properties of granite under uniaxial compression after being soaked in different chemical solutions (water, NaOH solution and HNO₃ solution) and subjected to different freeze-thaw cycles is experimentally studied. The damage mechanism of granite subjected to chemical soaking and freeze-thaw cycles is analyzed according to the micro mechanism and chemical mechanism. In addition, a damage variable is defined in terms of which the damage degree of granite can be analyzed quantitatively. The test results show that for all the chemical solutions (water, NaOH solution and HNO₃ solution), with the increase of freeze-thaw cycles, the relative Young’s modulus decreases by exponential function, the loss rate of the peak stress increases by power function, and the axial peak strain changes by Guass function. With the increase of freeze-thaw cycles, the damage and deterioration of granite in HNO₃ solution is larger at a smaller number of freeze-thaw cycles than that at a larger number of freeze-thaw cycles, while an opposite phenomenon is found for granite soaked in NaOH solution. The process of freeze-thaw damage is essentially a process in which the granite is damaged gradually by thermal stresses, meanwhile, the chemical damage produced by chemical dissolution together with the freeze-thaw damage can give mutual effects on the damage and deterioration of granite.