收集的样本和介质破裂倾向高Hongqinghe煤矿(HQH)和Nalinhe煤矿(NLH),分别。样品如图的位置
1。对于前者,它位于Yijinholo旗帜,中国内蒙古自治区鄂尔多斯市。这是一个单克隆结构1°3°倾斜的;折叠和错误并不发达,属于不含气的煤矿。只有3号煤层10倍破坏性的爆发在开采期间从2018年3月至11月,造成巷道伤害和设备损坏。样品来自9号煤层平均埋深约760米。对后者来说,这是接近Hongqinghe煤矿,位于乌审旗,中国内蒙古自治区鄂尔多斯市。3号煤层的屋顶主要属于不稳定的屋顶,在当地属于中等稳定的类型,和地板属于相对软(iii a)类型。样品取自3号煤层,经历了许多微震的事件,平均埋深600米或在那附近。样品都认真和迅速送往实验室,然后钻到尺寸的半圆柱体直径50毫米和25毫米的高度。 Both ends are trimmed to ensure that the unevenness is less than 0.01 mm, and the side is polished to make sure that the nonparallelism is not greater than 0.01 mm. The notches with 1 mm in width and 6/8 mm in length are machined at the center of the circle, and the top is sharpened by a diamond wire saw. The numbering rule of samples is the abbreviation of the coal mine; the width of the notch is the serial number of the sample. For example, N8-2 represents the sample from Nalinhe Coal Mine with 8 mm in width, and the order is 2. Industrial analysis and axial wave velocity tests are performed before CT and NSCB, and the results are illustrated in Table
1(
10]。
尽管采取的加固措施,一些问题仍然发生在测试期间,如快速破坏应变仪的样品和脱落,导致缺乏一些应变的测试数据。样品在加载点的荷载位移曲线测试如图
6,N8-2的数据丢失。它表明,样品的破裂过程包括压实阶段,弹性变形阶段,位移塑料增长阶段,和峰值破坏阶段后,位移塑料成长阶段并不明显。样品的最大负载HQH减少样品的宽度变化时从6毫米到8毫米。后峰值负载不同程度减少步骤,说明样品的主轴承结构改变,和声音可以听到明显在测试期间。轴承结构失败后,负载急剧下降,导致煤的破坏样品。H8-1更值得注意的是,数据比样品在同一组,被驱散。样本的最大负载NLH显然不会改变在不同宽度的级距,压实阶段相对温和,在加载点位移相对较大。N6-1和N6-2帖子前大幅下降,峰值负载样品损失,而后者滴在多层次的步骤。的结果和样品8毫米宽不同于别人。其中,N8-2损失过快,结果不是。 The compaction stage of N8-1 is short; the load in the post peak stage decreases in multilevel steps, accompanied by elastic energy dissipation. The N8-3 damages rapidly after the elastic deformation stage, and the residual strength is greater than N8-1. It could conclude that the failure behavior of the sample is related to its level of bursting proneness, the width of the notch, and other factors, under the same loading mode. The average maximum load of samples from HQH (high bursting proneness) is greater than that of NLH (medium bursting proneness), and the failure process is more sudden and thorough; even some strain gauges destroy completely. The larger width of notch would attenuate the maximum load of samples from HQH severely, and little for that of NLH.
声发射信号的阈值在测试设置为40 dB,和采样率设置为1 MHz。带头破坏试验是在装货前,以确保执行的声发射信号可以有效地获得。声发射系统的时间同步和试验机系统,以确保收集的数据进行同步。人员和设备应该保持安全距离,因为小煤炭块可能排出的现象在损伤,和环境的测试应该是黑暗和安静的来提高数据的准确性。结果表明,12煤样品的声发射特征非常离散,它是极其困难的,毫无意义的分析所有的样品的结果。H6-1、H8-3 N6-2, N8-1选择进行分析,和相关的结果如表所示
3。样品的抗拉强度是计算方程(
1),根据赵的建议等。
38]:
(1)
σ
=
4.976
P
马克斯
D
×
t
,在哪里
σ推断试样的抗拉强度(MPa),
P
马克斯代表的最大负载(N),
D是直径的样本,是一个常数等于100(毫米),然后呢
t代表样本厚度等于25 (mm)。
计划AE物理参数的样本。
样品
累积能量(105)
最大影响速率
抗拉强度(MPa)
H6-1
1.14
551年
1.99
H8-3
0.86
534年
1.67
N6-2
1.07
147年
1.35
N8-1
1.05
728年
1.47
3.4.2。分析样品的声发射特性
H6-1的关系、H8-3 N6-2, N8-1 NSCB测试之间的进化特性的压力、累积能量,影响速度,时间是在数字
8(一个)- - - - - -
8 (d),分别。它表明机械响应四个样品的四个阶段是截然不同的,即,compaction stage, elastic deformation stage, displacement plastic growth stage, and post peak failure stage. However, the evolutionary process of the parameters is basically consistent with the failure process of the internal structure of the sample. The compaction stage of H6-1 sustains long, and the cumulative energy and impact rate increase slowly, and the growth rate of the other three stages increases. The impact rate increases rapidly in the displacement plastic growth stage, but the value is not large, which indicates that damage in this stage is mainly microfracture extension. The impact rate decreases rapidly, and cumulative energy increases sharply in the post peak failure stage, which means damage is severe and residual stress is small. The acoustic emission feature of H8-3 and N6-2 in the first three stages are not obvious, but the impact rate fluctuates greatly with time in the last stage, which manifests that the failure of samples is not completed instantaneously. The failure duration of the latter is significantly longer than that of the former, which is due to the high bursting proneness of the former. The acoustic emission feature of N8-1 is weak in the compaction stage and enhanced in the other stages, especially in the displacement plastic growth stage. The impact rate fluctuates in the post peak failure stage and coincides with the step failure behavior of samples, which indicates that bearing structure changes during the failure process.
图的声发射parameters-time样本。
H6-1的关系、H8-3 N6-2, N8-1 NSCB测试之间的声发射事件RA值(上升时间/振幅)和平均频率AF价值(数/持续时间)数据所示
9(一个)- - - - - -
9 (d),分别。刘等人的建议下。
54),声发射波形演化过程中不同类型的骨折是不同的。一般来说,拉伸断裂的RA值低和房颤的价值高,剪切破坏的RA值高和房颤的价值很低,与RA值和房颤拉伸剪切混合故障相对较低的价值。煤的RA和房颤值在这个研究是分散的,有弱的规律性,这表明煤的次级断裂的演化过程非常复杂和高度离散的、拉伸断裂,剪切破坏,拉伸剪切混合共存时失败。声发射信号点的峰值破坏阶段更比其他阶段,这表明破裂过程的持续时间很短,和失败的强度很大。H6-1和H8-3切口的宽度增加;声发射事件AF高价值和低RA值显著降低在前三个阶段,这意味着减少煤炭的拉伸断裂。声发射事件增加,广泛分布于位移塑料增长阶段,这意味着许多类型的骨折共存。较低的声发射事件后房颤值和高RA值增加峰值破坏阶段,这显示了增加剪切断裂。N6-2和N8-1切口的宽度增加;压实阶段声发射事件数; that with high AF value and low RA value increases in the displacement plastic growth stage; likewise, that with low AF value and high RA value increases too. These indicate that both tensile fracture and shear fracture increase, and tensile shear mixed failure occurs in samples.
数值模拟结果的样本HQH和NLH如表所示
7。它认为外部负载,切口的宽度,矩阵和纯矿物的力学性能影响的应力、应变分布探测点。也为更多的人所认可的内部应力、应变的作用下对称结构对称分布对称负载,但内部应力、应变分布的数值模拟结果更复杂和不对称。的主要原因如下:(1)空间分布三个组件的示例是不对称的和随机的。(2)承载力三个组件的示例是截然不同的。煤炭是异构和各向异性,不同位置的局部力学性能示例也不同。(3)演化过程的应力、应变载荷模型很复杂,很有当地的差异。数值模拟的结果表明,样本的内部压力HQH远远大于NLH,和相同应变下逆转切口的宽度。此外,两个样本的应力和应变相同的煤矿和切口的宽度增长下降。失败的位置在示例(应力、应变是伟大的)基本上是在加载点或支持点附近,这将扩展到内部样本。 The phenomenon of the tensile zone and stress concentration at different degrees appears nearby the top of the notch. Secondary fracture initiates and extends upward under the continuous action of external load.