单轴压缩条件下冻融灰岩裂隙扩容及损伤破坏分析  

Analysis on Fracture Dilation and Damage Failure of Freeze-Thaw Limestone Under Uniaxial Compression

作　　者：宋心怡 宋彦琦[1] 马宏发 杨江坤 SONG Xinyi;SONG Yanqi;MA Hongfa;YANG Jiangkun(College of Mechanics and Civil Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China)

机构地区：[1]中国矿业大学(北京)力学与建筑工程学院,北京100083

出　　处：《矿业研究与开发》2024年第2期122-128,共7页Mining Research and Development

基　　金：国家重点研发计划项目(2018YFC0808402);国家重点实验室开放基金项目(SKLGDUEK2017)。

摘　　要：为研究冻融灰岩单轴压缩下裂隙应变演化及渐进损伤特征,开展了0次、10次、20次、40次灰岩冻融单轴压缩试验,建立了基于裂隙体应变特征的冻融灰岩损伤本构方程,结合PFC2D数值模拟分析了冻融灰岩的损伤破坏模式。结果表明:经历40次冻融循环后,灰岩的单轴抗压强度、弹性模量、泊松比由原来的109.88 MPa、65.38 GPa、0.225分别降至70.36 MPa、46.62 GPa、0.197;冻融10次、20次、40次灰岩裂隙体应变极值分别增至0.0106, 0.0146, 0.0269。基于体积应变拐点法及位移回归分析法得到的冻融灰岩扩容应力值随冻融循环次数增加而降低,两种方法所得结果的相对误差低于10%。基于裂隙体应变特征的理论应力-应变曲线与试验曲线具有较好的一致性,所建的损伤本构方程适用于低冻融次数灰岩。基于PFC2D所得的冻融灰岩单轴压缩破坏模式为劈裂破坏和“劈裂-剪切”破坏。In order to study the evolution of fracture strain and progressive damage characteristic law under uniaxial compression of freeze-thaw limestone,O,10,20 and 40 times of freeze-thaw limestone uniaxial compression experiments were carried out,the freeze-thaw limestone damage constitutive equation based on fracture body strain characteristics was established,the freezethaw limestone damage failure modes were explored with PFC2D numerical simulation software.The research shows that the uniaxial compressive strength,elastic modulus and Poisson's ratio of limestone decrease from 109.88 MPa,65.38 GPa,and 0.225 to 70.36 MPa,46.62 GPa,and 0.197,after 40 times of freeze-thaw cycles.The maximum values of limestone fracture body strain increase to 0.0106,0.0146,0.0269 after 10,20 and 40 times of freeze-thaw.Based on the volume strain inflection point method and the displacement regression analysis method,the freeze-thaw limestone dilation stress value decreases with the increase of the number of freeze-thaw cycles.And the relative error of the results obtained by the two methods is less than 10%.The theoretical stress-strain curve based on the fracture body strain characteristics is in good agreement with the experimental curve,the theoretical damage constitutive equation is more applicable to low freeze-thaw times of limestone.The uniaxial compression failure modes of freeze-thaw limestone based on PFC2D are split mode and"split-shear"mode.

关 键 词：冻融循环 力学参数 裂隙体应变 扩容应力 损伤本构 

分 类 号：TD315[矿业工程—矿井建设] TU45[建筑科学—岩土工程]