AE measurements in deep South African gold mines: Phase II - monitoring of rock mass damage by underground cavities and prediction of rockbursts

南非金矿采场附近约 1 公里深的岩体中部署了分布约 100 米的密集 3 维声发射传感器阵列。该地区存在多处地质断层。大量微裂缝几乎全部发生在地质断层断裂面附近或采矿前沿前方的高差应力区域。后者小事件的相对丰富程度与自然地震相似，但前者极端。事实证明，后者群体由几个离散的、大规模（几十米）、几米厚的板状簇组成。对矿井岩石样本的实验室测试表明，薄弱的叶理会影响微裂缝。此外，微裂缝活动和最终贯穿裂缝的复杂性都受到叶理相对于主应力轴方向的影响。

A dense, 3-dimensional array of AE sensors with about 100-m spread was deployed in the rock mass near a mining stope at about 1-km depth in a South African gold mine. The area contained multiple geological faults. A huge number of microfractures were occurring almost exclusively either in the great proximity of fracture planes of geological faults or in the zone of high-differential stress ahead of the mining front. Relative abundance of small events was to a similar extent to natural earthquakes in the latter, but was extreme in the former. It has turned out that the latter population consists of several, discrete, large-scale (a few tens of meters), tabular clusters of a few meters thickness. Laboratory tests of rock samples from the mine showed that weak foliation affects the microfractures. Also, complexities of microfracture activity and the eventual through-going fracture were both shown to be affected by the orientation of the foliation with respect to the principal stress axis.