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利用MTS815 Flex Test GT岩石力学试验系统及声发射(AE)三维定位实时监测系统,对4种不同粒径北山花岗岩进行断裂韧度试验,系统研究了不同粒度北山花岗岩的断裂力学行为及声发射特征。在三点弯曲试验条件下,北山花岗岩峰值过后断面还具有较大的承载面积。粒径越大,其峰值载荷越低,且屈服载荷所占峰值荷载百分比越小,断裂韧度值越小;粒径越大其破坏过程中的总变形量越大,且加载末期承载能力越高。细粒及中细粒岩样声发射事件最早出现于拉应力较大的尖端下部,而强度相对较小的粗粒及中粗粒岩样声发射事件最早出现于受点荷载的上端部。声发射事件集中出现于裂纹稳定扩张阶段,这一阶段为岩石断裂的最主要阶段。粒径越大,声发射事件越多,且整个断面分布越广泛。
Using the MTS815 Flex Test GT rock mechanics test system and acoustic emission (AE) 3D real-time monitoring system, the fracture toughness tests of Beishan granite with four different particle sizes were carried out. The fracture mechanics behavior and acoustic emission characteristics of Beishan granite with different particle sizes . Under the condition of three-point bending test, the section of Beishan granite also has a larger bearing area after the peak. The larger the particle size, the lower the peak load and the smaller the peak load percentage of yield load, the smaller the fracture toughness value; the larger the particle size, the greater the total deformation during the failure process, high. The acoustic emission events of fine-grained and medium-grained rock samples first appeared in the lower part of the tip where the tensile stress was larger, whereas the coarser and coarse-grained rock-like acoustic emission events with relatively lower intensity appeared earliest at the upper end of the point load. Acoustic emission events concentrated in the steady expansion of the crack stage, this stage is the most important stage of rock fracture. The larger the particle size, the more acoustic emission events, and the wider the cross-section distribution.