为探究酸性溶液作用下花岗岩力学特性损伤机制，在pH值分别为7、5、3的化学溶液中对花岗岩试件进行72 d饱和处理，然后对饱和试件和自然干燥试件进行三轴压缩试验、核磁共振试验、电镜扫描试验（〖WT５”《TNR》〗scanning
electron microscope, SEM〖WT５”ＢＺ〗）及X射线衍射试验，并对比分析不同化学溶液作用下花岗岩试件三轴抗压强度损伤、变形特征及力学参数的变化规律。试验结果表明： 1）花岗岩试件的三轴抗压强度、弹性模量及黏聚力随酸性溶液pH值降低而减小，泊松比随着pH值的降低而增大； 2）在酸性溶液的腐蚀作用下，试件内斜长石及方解石等矿物成分的消耗导致试件内部结构疏松程度增加，强酸作用下伴有微裂隙产生； 3）与自然干燥状态下的试件相比，在围压20 MPa的条件下经pH=3的酸性溶液酸化处理后的试件，其偏应力峰值强度降幅达39.94%； 4）花岗岩在酸性溶液作用下，部分矿物溶解、迁出，使得孔隙结构不断劣化产生大量次生孔隙，且酸性溶液pH值越低，中、大孔隙占比越高。
To investigate the damage mechanism of mechanical
properties of granite under the action of acidic solution, the granite is
saturated for 72 days in chemical solutions with pH values of 7, 5, and 3,
respectively. The saturated specimens and natural drying specimens are then
exposed to triaxial compression, nuclear magnetic resonance, scanning electron
microscope, and Xray diffraction tests. Finally, the
variation laws of triaxial compressive strength damage, deformation
characteristics, and mechanical parameters of granite specimens are compared
and analyzed in an acid solution. The results show the following: (1) The
triaxial compressive strength, elastic modulus, and cohesion of granite
specimens decrease with a decrease in pH value of an acid solution, whereas the
Poisson′s ratio increases with the decrease of pH
value. (2) The consumption of mineral components such as plagioclase and
calcite in the specimens by acid solution corrosion increases the degree of
internal structural porosity of the specimens, and microcracks are formed under
the action of strong acid. (3) When compared with the specimens under natural
drying conditions, the deviatoric stress peak of the specimens in acid solution
acidification with a pH value of 3 decreases by 39.94% under confining pressure
of 20 MPa. (4) As a result of the acid solution′s
action, some minerals of granite dissolve and migrate, resulting in the
continuous deterioration of pore structure and a large number of secondary
pores. The higher the proportion of medium and large pores in an acid solution,
the lower is the pH value.
