冻融损伤砂岩的能量演化及分段本构模型  

Energy evolution and piecewise constitutive model of freeze-thaw damaged sandstone

作　　者：贾蓬[1] 毛松泽 孙占阳 钱一锦 卢佳亮 JIA Peng;MAO Songze;SUN Zhanyang;QIAN Yijin;LU Jialiang(School of Resources and Civil Engineering,Northeastern University,Shenyang 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：《中南大学学报（自然科学版）》2023年第3期908-919,共12页Journal of Central South University:Science and Technology

基　　金：国家重点研发计划项目(2022YFC2903903);国家自然科学基金资助项目(52174071)。

摘　　要：为研究冻融砂岩受载过程中的损伤劣化规律,首先,对冻融0,25,50,75和100次的砂岩进行单轴压缩试验,获得不同冻融循环后损伤砂岩的应力-应变关系以及破坏模式;其次,基于能量演化及能量分配规律,分析不同冻融次数砂岩的损伤特性;最后,提出利用耗散能变化规律确定应力-应变曲线分段压密点的方法,建立冻融砂岩的分段损伤本构模型。研究结果表明:砂岩的强度和弹性模量随冻融次数增加而降低,砂岩的破坏模式逐渐由剪切破坏为主向张剪复合破坏转变;破坏后的裂纹数量逐渐增多,破坏表现为由脆性逐渐向延性破坏过渡;峰值应力处的总能量、弹性能、耗散能均随冻融次数增加,表现出“减小-增加-减小”三段式变化规律;弹性能耗比(耗散能与弹性能的比值)的最小值Kmin是判断砂岩从稳定状态转向非稳定状态的重要标志,是冻融砂岩破裂前的预兆指标。基于冻融和受荷损伤因子,建立了考虑压密段的分段损伤本构模型,能够更合理地描述冻融损伤砂岩的变形破坏过程。In order to understand the damage deterioration characteristics of freeze-thaw sandstone in the loading process,firstly,uniaxial compression tests were conducted on sandstones experiencing 0,25,50,75 and 100 freeze-thaw cycles and the stress-strain relationships,damage modes of damaged sandstones were obtained.Secondly,the damage characteristics of sandstone experiencing different freeze-thaw cycles were analyzed in terms of energy evolution and energy distribution law.Finally,the stress-strain curve compaction point was determined by using the energy dissipation law.A piecewise constitutive model of freeze-thaw sandstone was established.The results show that with the increase of the freeze-thaw cycles,the strength and elastic modulus of the sandstone decrease.The failure mode of the sandstone changes from shear failure to tensile-shear failure,and the failure behavior transforms from brittle failure to ductile failure with the increase of the freeze-thaw cycles.The total energy,elastic energy and dissipated energy at the peak stress all show a three-stage variation law of"decrease−increase−decrease".The minimum value of the elastic energy consumption ratio Kmin(ratio of dissipated energy to elastic energy)is a sign marking that the rock enters into the unstable stage,and therefore it can be used as a failure precursor.Based on the comprehensive damage factor of freeze-thaw and loading,a piecewise constitutive model considering the compaction stage is established,which can better describe the deformation process of freeze-thaw damaged sandstone.

关 键 词：冻融循环 能量演化 损伤 破坏前兆 分段损伤本构模型 

分 类 号：TU452[建筑科学—岩土工程]