开放性裂隙岩石三轴加载破坏前兆信息

Precursory Information of Triaxial Loading Failure of Open Fractured Rock

含节理的岩质边坡开挖卸荷时易发生突发性失稳破坏,对含不同岩桥长度的花岗岩试件开展三轴加载试验,运用红外热像仪全程采集,引入温度特征粗糙度,研究含节理岩石试件三轴加载过程中临空面上平均温度变化和温度特征粗糙度变化特征,将温度特征粗糙度与声发射振铃计数率和应力应变曲线对比分析。研究表明:温度特征粗糙度在试件破坏前夕出现突跳现象,而此时平均温度无任何异常表现,温度特征粗糙度前兆性优于平均温度;温度特征粗糙度与声发射振铃计数率和应力应变曲线三者阶段性较为一致,温度特征粗糙度突跳现象均略提前于声发射振铃计数率陡增和应力应变曲线下降;不同岩桥长度试件的温度特征粗糙度变化特征较为一致,以此作为研究指标受节理长度影响较小。研究结果可为节理岩质边坡开挖卸荷防治提供理论参考。

The rock slope with joints is prone to sudden instability when it is excavated and unloaded.A triaxial test was carried out on granite specimens with different length of rock bridges that were collected by infrared thermal imager in the whole process.The temperature characteristic roughness(TCR)was introduced and the variation characteristics of average temperature and TCR on free surface during triaxial loading process of rock with joints were studied.In addition,the TCR was compared with acoustic emission ring counting rate and stress-strain curve.Results show that the TCR had a sudden jump before the failure of the specimen,and the average temperature had no abnormal performance at this time,and the TCR precursor was better than the average temperature.The TCR was shown more consistent with the acoustic emission ring count rate and stress-strain curve,and the sudden jump of the TCR was slightly ahead of the acoustic emission ring count rate and steep.The variation characteristics in temperature and roughness of specimens in different rock bridge lengths were consistent,and less affected by joint length.The results provide a theoretical reference for unloading control of jointed rock slope excavation.