动力扰动和高温联合作用下砂岩力学特性及破坏特征  

Mechanical properties and failure characteristics of sandstone under combined effect of dynamic disturbance and high temperature

作　　者：任松[1,2] 李凯鑫 张平[1,2] REN Song;LI Kaixin;ZHANG Ping(State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing 400044,China;School of Resources and Safety,Chongqing University,Chongqing 400044,China)

机构地区：[1]重庆大学煤矿灾害动力学与控制国家重点实验室,重庆400044 [2]重庆大学资源与安全学院,重庆400044

出　　处：《中南大学学报（自然科学版）》2023年第3期1087-1097,共11页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(52074048)。

摘　　要：为分析不同动力扰动和温度条件下砂岩的力学特性和破坏特征,开展了单轴压缩试验和声发射试验。首先,对中粒径砂岩试件进行不同温度的加热;其次,进行单轴压缩并全过程监测声发射信号;最后,结合峰值应变、单轴抗压强度等数据,分析砂岩的力学特性及破坏特征。研究结果表明:循环扰动和温度作用对岩石强度影响极大,无循环扰动的试件抗压强度随温度升高而先上升后下降,其余试件抗压强度与两者呈负相关,且受温度影响更为显著;砂岩峰值应变随着温度升高呈先降低后上升的趋势,200℃为该类砂岩的拐点,砂岩峰值应变与循环扰动幅度呈正相关,有加速上升趋势,且对温度变化更敏感;试件临近破坏时,内部裂纹发展情况存在突变,R_(A)(上升时间与幅值之比)和FA(平均频率)的分布明显变化。F_(A)/R_(A)>K的声发射信号急剧减少、FA/RA<K的声发射信号陡然增多,新产生的裂纹中剪切裂纹占比很大,这种F_(A)/R_(A)的波动与实际物理过程一致且更提前,可作为岩石破坏先兆;随着循环幅度和温度增大,试件内部新产生裂纹的主要形式由张拉裂纹向剪切裂纹逐渐转变,试件的宏观破坏形式也由脆性破坏向延性破坏逐渐转变。In order to analyze the mechanical properties and failure characteristics of sandstone with different dynamic disturbances and temperatures,uniaxial compression tests and acoustic emission tests were carried out.Firstly,the medium-size sandstone samples were heated at different temperatures.Secondly,uniaxial compression test was carried out and the acoustic emission signal was monitored in the whole process.Finally,combined with the peak strain,uniaxial compressive strength and other data,the mechanical properties and failure characteristics of sandstone were analyzed.The results show that cyclic disturbance and temperature effect have great influence on rock strength.The compressive strength of the specimens without cyclic disturbance increases firstly and then decreases with the increase of temperature.The compressive strength of the other specimens is negatively correlated with both,and the effect of temperature is more significant.The peak strain of sandstone decreases firstly and then increases with the increase of temperature.200℃is the inflection point of this kind of sandstone.The peak strain of sandstone is positively correlated with the amplitude of cyclic disturbance,and has an accelerating upward trend,which is more sensitive to the change of temperature.When the specimen is close to failure,there is a sudden change in the internal crack development,and the distribution of R_(A)(ratio of rise time to amplitude)and F_(A)(average frequency)values change significantly.The acoustic emission signal of F_(A)/R_(A)>K decreases sharply,and the acoustic emission signal of F_(A)/R_(A)<K increases sharply.The shear crack accounts for a large proportion of the new cracks.The fluctuation of the F_(A)/R_(A) is consistent with the actual physical process and earlier,which can be used as a precursor of rock failure.With the increase of cycle amplitude and temperature,the main form of new cracks in the specimen gradually changes from tension cracks to shear cracks,and the macroscopic failure form of the specimen als

关 键 词：动力扰动 高温 砂岩 声发射 破坏模式 

分 类 号：TU451[建筑科学—岩土工程]