福建武夷山风景区红色砂砾岩单轴受压声发射实验

Experimental investigation on acoustic emission of red sandstone in Wuyishan scenic area under uniaxial compression

根据武夷山九曲溪风景区工程地质条件,对取自一线天景点岩体的白垩系崇安组红色砂砾岩样品进行声发射实验,得到样品在单轴压力加载过程中的应力-应变曲线,声发射参数与应力、应变、时间之间的关系。红色砂砾岩的破坏过程分为压密变形、弹性变形、塑性变形、破裂四个阶段,每个阶段声发射特征不同,声发射能量和振铃计数变化很大,岩石破裂时的声发射能量达到2×10^6mv×μs以上,振铃计数在2×10^4左右。实验发现,在塑性阶段,岩石的声发射累计能量和振铃次数相比较于弹性阶段中后期和破裂阶段更趋于平缓,存在一个平静期。FFT变换分析得出样品破裂时的主频为25 KHz和50 KHz。实验成果为武夷山风景区岩体稳定性监测技术开发提供了基础数据。

Three red sandstone samples of the cretaceous Chong-an group were taken according to the engineering geological conditions in Wuyishan scenic area. Experiments on acoustic emission（ AE）characteristics of three red sandstone samples are carried out on electro-hydraulic servo universal testing machine（ HUT） under uniaxial compression. The mechanical properties of rocks and AE characteristics including stress-strain curves,AE energy and ringing counts are obtained. The relations among AE parameters and stress-strain by time are analyzed in detail. On this basis,the failure process of red sandstone was divided into four stages： rock mass compaction stage,elastic deformation stage,plastic stage,rock fracture stage. AE energy and ringing counts have changed a lot in four stages. AE energy of rock burst are 2 × 10^6（ mv × μs）above,and at this time of ringing counts are at around 2 × 10^4. Compared with elastic deformation stage and rock fracture stage,the plastic stage＇s rock AE accumulated energy and ringing counts flatten out,which indicates there is a relatively tranquil period before the rock burst. The main frequency of rock failure is 25 and 50 KHz by fast Fourier transform analysis（ FFT）. The experimental results provide the basic data for monitoring technology design of rock stability based on AE in Wuyishan Scenic Area.