摘要
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。
The slopes of open-pit mine are always in freezing- thawing environment in permafrost region, and the surface rock of slopes is weathering during the freezing- thawing cycles. The cyclic freezing-thawing tests on the saturated sandstone from the mining area in Muli were completed in laboratory in order to understand the physical and mechanical characteristics of saturated rock in freezing-thawing cycles. The degradation model for the saturated rock was studied. The micro-fracture rate increases gradually with increasing the freezing-thawing cycles, but the uniaxial and triaxial compression strengthes and other physical parameters decreases with the number of the freezing-thawing cycles. The micro-fracture propagation factor was suggested according to the micro-fracture change in the freezing-thawing cycles. The theoretical damage model and constitutive relations of rock strength were established using the micro-fracture propagation factor. The proposed model explained quantitatively the damage of the saturated rock due to freezing-thawing. The theoretical strength calculated with the damage model matched well with the test results. The composite stress generated due to water transformation to ice exceeded the strength of rock and drove the micro- fracture to expand.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2016年第12期2561-2571,共11页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(50879608)
中国科学院西北生态环境资源研究院冻土工程国家重点实验室开放基金项目(SKLFSE201311)
中煤科工集团西安研究院有限公司科技创新基金项目(2012XAYCX020)~~
关键词
岩石力学
冻融循环
饱和岩石
微裂隙扩展因子
劣化模型
rock mechanics: freezing-thawing cycles
saturated rock
micro-fracture propagation factor
damagemodel