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高海拔多年冻土区露天煤矿岩质边坡常年处于冻融交替环境中,边坡浅部病害显著。为了分析边坡上岩石在冻融环境中的劣化规律,利用采集于木里地区露天矿边坡钻孔中的砂岩试样进行了室内饱和冻融循环试验,并建立了饱和岩石冻融劣化的理论模型。岩样冻融循环试验结果显示随着冻融循环次数的增大,饱和砂岩的微裂隙率逐渐增大,单轴和三轴抗压强度以及表示岩石质量的常见物理参数逐渐降低。基于岩石在冻融循环过程中的微裂隙变化,提出并推导了微裂隙扩展因子,理论建立了岩石强度随冻融循环变化的劣化模型和本构关系,利用劣化理论模型所计算的岩石强度与试验结果吻合较好。分析岩石微裂隙的变化规律,可以获得饱和砂岩在冻融循环环境中的劣化是由于岩石内部的微裂隙在水成冰相变过程中产生的巨大复合应力超过了岩石微裂隙开裂强度,而导致微裂隙逐渐失稳扩展,岩石整体性被削弱等结论。
Rocky slopes of opencast coal mines in permafrost regions at high altitude all year round are in an alternate environment of freezing and thawing, and the diseases in the shallow parts of the slopes are significant. In order to analyze the rule of rock degradation in freezing and thawing environment, the indoor saturated freeze-thaw cycle test was carried out by using sandstone samples collected from the borehole of open pit mine in Muli area, and the freezing and thawing deterioration of saturated rock Theoretical model The results of freeze-thaw cycles show that with the increase of the number of freeze-thaw cycles, the micro-fracture rate of saturated sandstone gradually increases, and the uniaxial and triaxial compressive strengths and the common physical parameters of rock quality decrease gradually. Based on the variation of microcracks during the freeze-thaw cycles, the microcrack expansion factor was proposed and deduced. The degradation model and constitutive relationship of rock strength with the freeze-thaw cycle were theoretically established. The relationship between rock strength and The test results agree well. The variation of micro-fissures in rocks can be obtained. The deterioration of saturated sandstone in the freeze-thaw cycles is caused by the fact that the micro-fissures generated during the ice-forming phase of micro-fissures in the rock exceed the micro-fissures of the rock and lead to The gradual instability and expansion of micro-cracks, rock integrity is weakened conclusions.