冻融裂隙砂岩三轴压缩破坏特征宏细观试验研究

裂隙岩体在冻融作用影响下在其内部产生损伤,为研究不同裂隙砂岩冻融作用下的力学特性、破坏模式及细观孔隙结构,采用三轴压缩试验和核磁共振试验开展冻融裂隙砂岩三轴压缩的宏细观损伤破坏规律的研究。结果表明：冻融后砂岩的峰值强度、弹性模量降低,泊松比呈倒“V”形,峰值强度随着裂隙倾角的增大呈现出逐步递减的趋势,裂隙倾角为90°时为最不利情况;破坏后岩样内部中孔升高,大孔大幅提升,宏观上表现为砂岩在三轴压缩过程中出现明显裂缝,且裂隙砂岩在冻融作用后的破坏模式趋于复杂;核磁共振谱面积随裂隙倾角的增大而增大,破坏后谱面积进一步增大,T₂谱出现新的第三峰,大孔隙占比增大。冻融作用下寒区裂隙岩体的宏细观破坏规律的研究对寒区岩体工程稳定性评价具有重要意义。

Macro-fine and micro-experimental study of triaxial compression damage characteristics of freeze-thaw fractured sandstone

In order to study the mechanical properties and macro- and fine-scale damage characteristics of single fractured sandstones with different dips after freeze-thaw in the triaxial state before and after freeze-thaw, basic physical and mechanical tests and NMR tests were conducted on rock samples before and after freeze-thaw and after damage,The results show that: (1) Under triaxial compression, the peak strength of sandstone shows a gradual decreasing trend, the elastic modulus decreases and the Poisson"s ratio increases, with the most unfavorable situation when the fracture dip angle is 90°; (2) fractured sandstone under the action of three-way force, macroscopically the fracture positive and negative directions to generate a smaller width of the wing cracks, and continuous extension, and eventually local shear damage mode; (3) The NMR spectral area increases with the increase of fracture inclination, the pore proportion of small pore distribution increases, the spectral area increases further after the destruction, a new third peak appears in the T2 spectrum, and the proportion of large pores increases.