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为探讨高寒地区高陡岩质边坡的时效劣化机制,对经历不同冻融循环次数后的石英砂岩进行常规三轴和三轴蠕变试验,分析了冻融作用对岩石在短期受荷和长期受荷下的力学特征。试验结果表明,冻融作用对短期受荷下砂岩力学性能影响较小,常规力学参数及声发射现象随着冻融循环次数增加变幅较小;在长期受荷作用下冻融对砂岩时效力学特征影响显著,表现为各蠕变力学参数均随冻融循环次数增加而明显变化,是由于冻融导致裂隙壁疲劳受损,其后壁上颗粒在长期荷载作用下能够充分调整变形,冻融造成的微损伤会引起较强的蠕变性。提出考虑冻融蠕变损伤差异的长期折减系数,表征冻融后岩石抵抗长期荷载的能力。冻融后岩样在短期荷载及长期荷载作用下的破坏模式均为剪切破坏,但在长期荷载作用下的岩石破碎方式随着冻融循环次数增加逐渐由单一的斜剪切面向“X”状共轭剪切面演化,岩石更加破裂。研究结果对于高寒山区重大工程的全寿命周期评价具有重要意义。
In order to explore the mechanism of aging deterioration of high and steep rock slopes in the alpine region, the conventional triaxial and triaxial creep tests were carried out on the quartz sandstone subjected to different freeze-thaw cycles, and the effects of freeze-thaw on the rock under short-term loading and long-term Mechanical characteristics under load. The experimental results show that the freeze-thaw effect has little effect on the mechanical properties of sandstone under short-term loading, and the conventional mechanics parameters and acoustic emission phenomena change slightly with the increase of the number of freeze-thaw cycles. Under long-term loading and thawing conditions, The results show that all the creep mechanical parameters obviously change with the increase of the number of freeze-thaw cycles, which is due to the fatigue damage of the crack wall caused by freeze-thaw, and the particles on the wall can fully adjust the deformation and freeze-thaw under the long-term load Caused by micro-damage will cause a strong creep. A long-term reduction factor considering the difference of freeze-thaw creep damage is proposed to characterize the capacity of rock after freeze-thaw resistance against long-term loads. After the freezing and thawing, the failure modes of the rock samples under both short-term and long-term loads are all shear failure. However, the rock failure mode under long-term loading gradually changes from single oblique shear to "Conjugate shear plane evolution, the rock more cracked. The research results are of great significance to the life-cycle assessment of major projects in the alpine region.