摘要
采用双轴伺服控制试验机对干燥和饱水花岗岩进行巷道岩爆模拟实验,同时采用声发射系统监测并采集数据,研究了水对花岗岩岩爆过程中声发射特征的影响。结果表明:岩爆过程中饱水岩样事件率呈上升趋势,峰值载荷前没有事件率平静期,而干燥花岗岩事件率呈下降趋势,峰值载荷前有明显的事件率平静期;自水平方向卸荷开始,岩样振铃计数率、能率突增,饱水岩样事件率高于干燥岩样,但振铃计数率、能率均低于干燥岩样,且有几段振铃计数率平静期,表明水的存在丰富了声发射活动,但降低了声发射信号强度,降低了微观破裂的活动性;干燥花岗岩振铃计数率峰值发生在峰值载荷附近,而饱水岩样振铃计数率峰值出现时距离峰值载荷较远;主破裂前声发射非均匀性指标Cv值的快速上升,表明岩样内部出现大破裂或裂缝贯通,声发射事件局部集中程度加强,造成其声发射事件分布的非均匀性增强,可作为岩爆发生的前兆特征。
An experiment was carried out to simulate rock burst on dry and saturated granites with biaxial rigid servocontrolled testing machine.Meanwhile,an AE system was used to monitor and collect data for studying the influence of water on the AE characteristics during rock burst.The results showed that the AE event rate of saturated granite was rising in the process of rock burst without quiet period before peak load.However the AE event rate of dry granites was falling in the process of rock burst with obvious quiet period before peak load.The ring count rate and energy rate of samples suddenly increased since horizontal unloading.The AE event rate of saturated granite was higher than that of dry granite,but the ring count rate and energy rate were lower,with several quiet periods of the ring count rate.It indicated that water enriched the AE activities but reduced the intensity of AE signal and the activity of microcosmic rupture.The peak ringing count rate of dry granite occurred near the peak load,however,that of saturated granite occurred far from peak load.The Cv value rapidly rose before main failure,which indicated that large fracture or thorough crack appeared within the sample.As a result,the partial centralization of AE event was strengthened,causing the heterogeneity of distribution with AE event strengthened.Rapid rising of Cvvalue can be used as a precursory characteristic of rock burst.
出处
《矿业研究与开发》
CAS
北大核心
2015年第6期82-87,共6页
Mining Research and Development
基金
国家自然科学基金项目(51374088
51174071)
河北省自然科学基金项目(E2012209047)
