不同含水率煤岩受压变形破坏全过程声发射特征试验研究

 以晋城煤业集团赵庄矿3#煤层的无烟煤为研究对象，运用京岛AG–250kN刚性岩石试验机、数字式应变数据采集仪、声发射监测系统和自行研制的煤岩固–气耦合细观力学试验装置，进行不同含水率煤样在常规单轴压缩下的声发射特征试验。结果表明，含水率的不同使煤样的强度和声发射特征产生明显差异，随着含水率的增加，煤样的单轴抗压强度逐渐减小。干燥状态的煤样强度较大，整个破坏过程中的变形较大，弹性变形阶段持续时间较长。在密实阶段，不同含水率的煤样几乎没有出现声发射信号，干燥状态的煤样只出现少量的信号且基本没有变化，干燥状态的煤样声发射平均事件率为不同含水率煤样的4～10倍。进入弹性阶段后，不同含水率的煤样和干燥状态的煤样的声发射事件率均比较稳定，声发射平均事件率相差不大，但干燥状态的煤样声发射事件率持续时间更长。进入塑性阶段，不同含水率的煤样与干燥状态的煤样的声发射信号均明显增大，与弹性阶段相比，煤样的声发射平均事件率是弹性阶段的5～7倍。进入破坏阶段后，不同含水率的煤样声发射事件率低于干燥状态的煤样。含水量增加使声发射累积振铃计数减少，同时使产生明显声发射的时间滞后，试验结果表明水对煤样的力学特性和声发射特征有明显影响。

EXPERIMENTAL STUDY OF ACOUSTIC EMISSION CHARACTERISTICS OF COAL SAMPLES WITH DIFFERENT MOISTURE CONTENTS IN PROCESS OF COMPRESSION DEFORMATION AND FAILURE

Focusing on anthracites of No.3 coal seam in Zhaozhuang Mine，Jincheng Coal Mining Group，an experimental study was carried out to investigate the acoustic emission(AE) characteristics of coal samples with different moisture contents in conventional uniaxial compression test，by using island AG–250kN rigid rock testing machine，digital strain data acquisition instrument，AE monitoring system and self-developed coal-gas coupling micromechanics experimental device. The results show that the strength and AE characteristics of coal samples with different moisture contents have significant difference；and with the increase of moisture content of coal，uniaxial compressive strength of coal sample decreases gradually. The coal sample has greater strength and larger deformation in failure process；and it is almost linear elastic deformation happens before peak，continuing for a long time. In densification region，coal samples with different moisture contents have no AE signal，but there are only a small amount of signals in coal samples in dry state，basically without change. And its average AE event rate is 4–10 times as many as coal samples with different moisture contents. In elastic stage，the AE event rates of coal samples with different moisture contents and samples in dry state are all relatively steady and similar，but the duration of AE event rate in coal samples is longer in dry state. In the plastic stage，the AE signals in the two kinds of coal samples increase evidently. Average AE of coal samples in this stage is 5–7 times as many as that in elastic stage. In the failure stage，the duration of AE event rate of coal samples with different moisture contents is lower than those in dry state. Increasing water content makes ring count reduced，and the time of obvious AE lag. Experiment results show that water has obvious effects on the mechanical properties and AE characteristics of coal samples.