摘要
为探究含初始卸荷损伤砂岩的三轴蠕变力学特性,借助MTS816岩石力学试验系统通过控制卸荷量制备了不同初始卸荷损伤程度的砂岩试样,开展了卸荷损伤砂岩分级加载三轴蠕变力学试验,分析了初始卸荷损伤程度对砂岩应变特征、蠕变速率、变形模量、长期强度及破坏模式的影响规律。研究结果表明:(1)分级蠕变条件下,不同初始卸荷损伤程度砂岩的轴向和环向应变均呈阶梯式增长,轴向瞬时应变随载荷水平的增加呈近线性增长趋势,而环向瞬时应变呈非线性增长趋势,且随初始卸荷损伤程度的加剧,增加单位荷载引起的轴向瞬时应变增量不断增加;(2)卸荷损伤砂岩在非破坏阶段经历了瞬时变形、减速蠕变和稳态蠕变3个阶段,稳态蠕变速率随初始卸荷损伤程度的增加呈指数增长趋势;砂岩在破坏阶段经历了瞬时变形、减速蠕变、稳态蠕变和加速蠕变4个阶段,其中加速蠕变阶段用时极短,却能产生较大的扩容变形,导致岩样发生失稳破坏;(3)砂岩蠕变总时长、平均变形模量和长期强度均随初始卸荷损伤程度的增加呈非线性减小趋势,当初始卸荷损伤程度超过70%后,砂岩蠕变总时长、平均变形模量和长期强度降幅急剧增加,最高可达24.77%、33.28%和21.79%;(4)随着初始卸荷损伤程度的增加,砂岩蠕变破坏模式由单一的剪切破坏逐渐向复杂的张拉-剪切混合式破坏转变。
To investigate the triaxial creep mechanical properties of unloading-damaged sandstone,some sandstone samples with different unloading damage degrees were prepared by controlling the unloading amount using the MTS816 rock mechanics test system.Triaxial creep mechanical tests with graded loading were carried out on the aforementioned unloading-damaged sandstone to analyze the influence of initial unloading damage degree on the strain characteristics,creep rate,deformation modulus,long-term strength,and failure mode of sandstone.The results show that:(1)Under the condition of graded creep,both the axial and radial strains of sandstone with different initial unloading damage degrees stepwise grow.The axial instantaneous strains exhibit an almost linear growth trend with increasing loading levels,whereas the radial instantaneous strain shows a nonlinear growth trend.Moreover,as the initial unloading damage degree increases,the increment of axial instantaneous strain caused by increasing unit loading continuously increases.(2)The unloading-damaged sandstone undergoes three stages in the non-destructive stage:instantaneous deformation,deceleration creep,and steady creep.The steady creep rate increases exponentially with the increase of initial degree of unloading damage.In the failure stage,the sandstone experiences four stages:instantaneous deformation,deceleration creep,steady creep,and accelerated creep.Among them,the accelerated creep stage takes a very short time but can produce significant expansion deformation,leading to unstable failure of the rock sample.(3)The total creep time,average deformation modulus,and long-term strength of sandstone all show a non-linear decreasing trend as the initial unloading damage degree increases.When the initial unloading damage degree surpasses 70%,there is a sharp decline in the total creep duration,average deformation modulus,and long-term strength of sandstone,with the maximum reductions being 24.77%,33.28%,and 21.79%,respectively.(4)As the initial unloading damage degree increases,the creep failure mode of sandstone gradually transitions from a single shear failure to a complex tension-shear mixed failure.
作者
范浩
王磊
罗勇
朱传奇
FAN Hao;WANG Lei;LUO Yong;ZHU Chuan-qi(State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine,Anhui University of Science and Technology,Huainan,Anhui 232001,China;School of Resources Environment and Safety Engineering,University of South China,Hengyang,Hunan 421001,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2024年第S01期277-288,共12页
Rock and Soil Mechanics
基金
安徽理工大学引进人才科研启动基金项目(No.2021yjrc15)
安徽省科技重大专项项目(No.202203a07020010)
深部煤矿采动响应与灾害防控国家重点实验室开放课题(No.SKLMRDPC20KF03,No.SKLMRDPC21KF09)
关键词
岩石力学
卸荷损伤
分级蠕变
长期强度
破坏模式
rock mechanics
unloading damage
graded creep
long-term strength
failure mode
作者简介
第一作者:范浩,男,1992年生,博士,讲师,主要从事煤矿采动岩石力学方面的研究。E-mail:fanhao2014@126.com;通讯作者:王磊,男,1980年生,博士,教授,博士生导师,主要从事煤矿地下安全开采方面的研究。E-mail:leiwang723@126.com
