饱水裂隙岩石冻融变形特性研究  

Study on the freeze-thaw deformation characteristics of saturated fractured rocks

作　　者：贾蓬[1] 王晓帅 王德超 JIA Peng;WANG Xiao-shuai;WANG De-chao(School of Resources and Civil Engineering,Northeastern University,Shenyang,Liaoning 110819,China)

机构地区：[1]东北大学资源与土木工程学院,辽宁沈阳110819

出　　处：《岩土力学》2023年第2期345-354,共10页Rock and Soil Mechanics

基　　金：国家重点研发计划(No.2022YFC2903903);国家自然科学基金(No.52174071)。

摘　　要：寒区岩体在裂隙水冻胀作用的影响下发生损伤劣化,严重威胁寒区工程建设安全。针对孔隙率不同的绿砂岩、红砂岩和花岗岩开展了饱水裂隙岩石的冻融循环试验,分析了不同裂隙长度、裂隙宽度和岩性的岩石在冻融循环过程中随时间和温度变化的变形规律,得到了饱水裂隙岩石冻融变形特征值的变化特征,探究裂隙长度、裂隙宽度及岩性对冻融应变特征值的影响,分析了裂隙岩石冻融变形特性和破坏机制。试验结果表明:(1)不同裂隙几何参数岩石冻融应变变化过程可分为7个阶段:冷缩阶段、冻胀阶段、冻胀趋稳阶段、热胀阶段、融缩阶段、融缩回弹阶段和融缩趋稳阶段;(2)饱水裂隙岩石冻融应变随温度变化的曲线为不能闭合的滞回环,出现“冻融滞回”现象,且随冻融次数增加,滞回环逐渐上移,残余应变逐渐增加;(3)饱水裂隙岩石冻融应变特征值包括最大应变、残余应变、冻胀幅值和融缩幅值,且应变特征值与裂隙长度、裂隙宽度和岩体岩性相关,裂隙岩石冻融破坏是残余应变逐渐累积的过程。The fractured rock mass in cold areas is damaged and deteriorated due to crevice-water frost heaving,which seriously threatens the safety of engineering construction in cold regions.In this study,freeze-thaw cycling tests were conducted on green sandstone,red sandstone and granite samples of different porosities.The strain changing with time and temperature of saturated fracture during freeze-thaw cycling under influences of fracture length,width and lithology were analyzed.The changing rules of the characteristic values of fracture strains and the failure mechanism of fractured rock were also studied.Experimental results show that the change rule of freeze-thaw strain of fractured rock mass with different fracture geometry parameters can be divided into seven stages:the cool shrinkage stage,the frost heave stage,the frost heave stabilization stage,the thermal expansion stage,the thaw shrinkage stage,the thaw shrinkage rebound stage,and the thaw shrinkage stabilization stage.The curve of freeze-thaw strain versus temperature of saturated fractured rock mass is an unclosed hysteresis loop.The phenomenon of“freeze-thaw hysteresis”occurs,and with the increase of freeze-thaw cycles,the hysteresis loop gradually moves up,leading to a gradual increase of the residual strain.Characteristic values of freeze-thaw strain of saturated fractured rock mass include:the maximum microstrain,the residual strain,the frost heave amplitude,and the thaw shrinkage amplitude.The characteristic value of strain is related to the fracture length,the width and lithology of rock mass,and the freeze-thaw failure of fractured rock mass is caused by gradual accumulation of the residual strain.

关 键 词：裂隙岩体 冻融变形 滞回环 残余应变 

分 类 号：TU457[建筑科学—岩土工程]