片麻岩单轴压缩条件下破裂过程AE试验研究

AE CHARACTERISTICS OF GNEISS FRACTURE PROCESS UNDER UNIAXIAL COMPRESSION

本文针对小湾水电站坝基典型片麻岩实际,通过磨片试验分析了黑云母花岗片麻岩的矿物组成和结构,印证了岩石强度与矿物含量以及矿物强度有关。对该片麻岩进行了单轴压缩破裂过程声发射特性试验,研究了该黑云母花岗片麻岩的破裂失稳的声发射过程,分析了岩石内部裂纹随时间、应力、应变变化,对应声发射发展形态,这对于分析岩石破裂失稳机制十分有意义的。试验结果表明:片麻岩属于坚硬-极坚硬岩石,声发射活动规律大体相同,存在明显AE增强点。岩石破裂过程中的声发射振铃计数率适合用来预测岩石的破裂各个阶段。片麻岩的应力-应变关系满足2次多项式关系、应变-声发射累计数关系都满足3次多项式关系。有助于我们进一步认识岩石的破坏机理以及岩石破坏的前兆判据。

This paper examines a typical gneiss forming the foundation Xiaowan Hydropower Station.Grinding test is ued to analyze the formation environment and mineral composition of the biotite granite gneiss.The results confirm the relationship of the rock strength with its mineral content and mineral strength.Furthermore,acoustic emission is carried out during the uniaxial compression tests of the biotite granite gneiss samples.The acoustic emission process is examined during the biotite granite gneiss instability and rupture.the AE results are used to analyze the crack propagation with time,stress and strain.The results are meaningful for the analysis of rock fracture instability mechanism.They reveal that the gneiss is hard-very hard rock.Acoustic emission activities substantially follow the same patterns.There is a clear point of AE enhancement.Acoustic emission ring count rate of rock rock failure process is suitable for predicting for all stages of the breakdown of rocks.The relations of gneiss stress-strain are in the form of polynomials of second orders.The relations of strain-the cumulative number of AE are in the forms of polynomials of third orders.It will help us to better understand the failure mechanism and the precursor of rock failure criterion.