冻融循环作用下受荷青砂岩的脆性演化特征  

Brittleness evolution characteristics of cyan sandstone under freeze-thaw cycles

作　　者：高峰[1,2] 曹善鹏 熊信 周科平[1,2] 朱龙胤 GAO Feng;CAO Shan-peng;XIONG Xin;ZHOU Ke-ping;ZHU Long-yin(School of Resources and Safety Engineering,Central South University,Changsha,Hunan 410083,China;Research Center for Mining Engineering and Technology in Cold Regions,Central South University,Changsha,Hunan 410083,China)

机构地区：[1]中南大学资源与安全工程学院,湖南长沙410083 [2]中南大学高海拔寒区采矿工程技术研究中心,湖南长沙410083

出　　处：《岩土力学》2020年第2期445-452,共8页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51474252,No.51774323);湖南省研究生科研创新项目资助(No.CX20190220);中南大学中央高校基本科研业务费专项资金资助(No.2019zzts164)。

摘　　要：为研究寒区受荷岩石的脆性演化特征,开展了青砂岩的冻融循环试验和三轴压缩试验,通过脆性评价指数将冻融循环作用下受荷砂岩的脆性程度进行了量化,分析了不同冻融循环次数和不同围压对岩石脆性指数的影响规律。基于青砂岩脆性指数对围压的敏感性规律,建立了以脆性劣化因子β和岩性特征量λ为参数的脆性指数演化模型,并选取与该模型相同的函数模型对试验数据进行拟合验证。结果表明:同一冻融循环作用下,青砂岩的脆性程度随着围压增大而减弱,同时脆性指数变化速率对围压表现出较强的敏感性,围压越大,岩石脆性指数的衰减速率则越小;同一围压条件下,青砂岩的脆性随冻融循环次数增加而降低,单位冻融循环造成的脆性劣化效果随冻融循环次数增加而增强;脆性指数演化模型对冻融青砂岩以及常规黑砂岩、大理岩脆性指数的拟合数据具有较好的相关性,参数β和λ的拟合数据很好地反映了不同冻融循环和不同类别岩石的脆性演化特征。In order to study the brittle characteristics and evolution law of the rock in the cold region,the freeze-thaw cycle test and triaxial compression test of the cyan sandstone were carried out.The brittleness evaluation index is used to quantify the brittleness of the cyan sandstone under the freeze-thaw cycle.Then the effects of freeze-thaw cycles and confining pressure on the brittleness of cyan sandstone are analyzed.Based on the sensitivity law of brittleness index of cyan sandstone to confining pressure,a brittle exponential evolution model with brittleness degradation factorβand lithology characteristicλas parameters is established.Test data is verified by the same functional model.The results show that the brittleness of the cyan sandstone weakens with the increase of confining pressure and the rate of change of brittleness index shows strong sensitivity to confining pressure.The larger the confining pressure,the smaller the decay rate of the rock brittleness index under the same freeze-thaw cycles.Under the same confining pressure condition,the brittleness of the blue sandstone decreases with the increase of the number of freeze-thaw cycles,and the effect of brittleness degradation caused by unit freeze-thaw cycles increases with the number of freeze-thaw cycles.The brittleness exponential evolution model has a good correlation with the fitting data of freeze-thawed cyan sandstone,black sandstone and marble,and the parametersβandλaccurately reflect the brittle evolution characteristics of different freeze-thaw cycles and different rocks.

关 键 词：脆性指数 冻融循环 三轴压缩 演化特征 

分 类 号：TD315[矿业工程—矿井建设]