水-岩作用下砂岩微细观结构变化特性及机理研究

为了较好地分析水-岩作用下库岸边坡消落带岩体的劣化机理,设计进行了考虑库水压力升降变化和浸泡-风干循环的水-岩作用试验。研究结果表明:(1)在水-岩作用过程中,砂岩的单轴抗压强度劣化趋势明显,其中前6期抗压强度劣化趋势较为显著,6次水-岩作用之后,岩样的强度劣化趋势逐渐趋于缓慢。(2)随着水-岩作用周期的增加,岩石内部孔隙、裂隙逐渐发育、汇集,矿物颗粒逐渐软化、分解,使得岩石微观结构逐渐趋于松散。(3)水-岩作用下砂岩劣化的进程中,首先是岩样中胶结物的溶解、溶蚀,然后是失去胶结物包裹的矿物颗粒表面发生水-岩物理化学作用,最后是矿物颗粒本身软化、分解。(4)水-岩作用过程中,岩样内部胶结物的溶解、溶蚀对水-岩作用前期的宏观力学性质影响明显,岩石矿物颗粒本身的软化、分解对水-岩作用后期的力学性质影响明显。相关研究成果可为库岸边坡消落带水-岩作用机理分析提供较好的参考。

Research on Characteristics and Mechanism of Micro-structure Variation in Sandstone under Water-rock Interaction

In order to better understand the degradation mechanism of rock mass in the reservoir bank under water-rock interaction, a water-rock interaction experiment considering reservoir water level fluctuation and soaking-air drying cycle was designed and conducted. Research results show that: (1) It''s obvious that the axial compression strength of sandstone decreases dramatically during the water-rock interaction process, especially in the first-six periods. After six water-rock interaction periods, the strength deterioration of rock samples tends to be slower. (2) With the increase of water-rock interaction cycles, the rock sample'' s fracture is constantly deepening and broadening and the particles are slowly softening and decomposing, leading to a gradually loose of the rock microstructure. (3) During the sandstone degradation process under water-rock interaction, the dissolution and corrosion of cement begin first, and then the physical and chemical interactions between water and rock generate on the surface of mineral particles without the protection of cement package. The last process is the softening and decomposition of mineral particles themselves. (4) During the water-rock interaction process, it is obvious that the macroscopic mechanical properties of rock samples are controlled by the dissolution and corrosion of cement in the early stages and by softening of mineral particles in the later stages. The research results can provide a good reference for the analysis of the water-rock interaction mechanism of the reservoir bank slope.