水岩作用下露天坑边坡岩石蠕变试验分析

为了探究水位升降对边坡长期稳定的影响,选取莱州仓上露天坑边坡岩石,对经历不同饱水-失水循环次数的岩样进行了三轴蠕变试验。通过分析SγJH蠕变应变-时间曲线及蠕变速率曲线,探究边坡岩石经历饱水-失水循环作用后的蠕变性质变化。进一步利用电镜对经历不同循环次数的SγJH岩样进行扫描,从细微观角度分析了水岩作用对矿坑边坡岩石损伤机理。结果表明:随饱水-失水循环次数增加,相邻循环次数下的SγJH轴向蠕变应变最多提高31%,侧向提高33%;SγJH-15后瞬时弹性应变较SγJH-0提高了54.3%,相邻荷载等级下蠕变应变提高24.3%,蠕变总应变可达到三轴压缩极限应变的80%以上。经历饱水-失水循环后,SγJH稳态蠕变速率不再为0,而是随饱水-失水循环次数增加不断提高,SγJH-15第5级荷载作用下稳态流变速率达到29.2×10^-6/h;在施加各级轴向荷载的瞬时,初期蠕变速率加速度亦有所提升。水岩作用下岩石力学性质变化机理研究方面,由于SγJH内部结构的非均质性,在饱水-失水循环作用下岩样发生微观弱化和破裂,使得原有的应力平衡被打破,从而造成岩石变形曲线产生了不规则波动和突变。

Creep Curve of Rock at Open-pit Slope underWater-rock Interaction

In the aim of investigating the long-term effect of water level fluctuation on slope stability, rock samples from Cangshang open-pit slope in Laizhou City were selected for triaxial creep test under different saturation-dehydration cycles.By analyzing creep strain-time curves and creep rate curves of SγJH, the creep properties of slope rock after saturation-dehydration cycles were explored.Furthermore, SγJH rock samples after different cycles were scanned by electron microscopy to analyze the damage mechanism of rock under water-rock interaction in microscopic scale.Results indicate that, 1) along with the increasing of saturation-dehydration cycles, axial creep strain increased up to 31%, and the lateral creep strain increased by 33% under adjacent cycle times;2)instantaneous elastic strain of SγJH-15 improved by 54.3% than that of SγJH-0,creep strain at adjacent load level increased by 24.3% and total creep strain of SγJH reached 80% or above of limit strain in triaxial compression test;3) with the increasing of saturation-dehydration cycles, steady creep rate became nonzero and steady rheological rate of SγJH-15 at the fifth level of loading reached up to 29.2×10-6 h;4)at the moment of applying axial load at all levels,initial creep rate acceleration also increase.In the research field of mechanical properties of rock under water-rock interaction, microscopic weakening and rupture occurs in rock samples under the cycle action due to heterogeneous internal structure of SγJH.Hence the original stress balance is broken, resulting in irregular fluctuations and abrupt change of rock deformation curve.