基于NRBO-XGBoost的煤体破坏声发射特征及裂纹扩展状态智能识别

Intelligent identification of coal mass acoustic emission characteristics and crack propagation state based on NRBO-XGBoost

  • 摘要:目的】 煤岩动力灾害事故与煤岩破坏的复杂性和不确定性密切相关,准确识别煤岩裂纹扩展状态是研究其失稳破坏的重要途径,目前基于声发射物理量信息的识别方法存在速度慢、效率低等问题,难以满足煤矿安全、高效和智能化开采需求。【方法】 为实现煤体裂纹扩展状态的智能识别,通过分布式梯度增强库(XGBoost)构建一种基于牛顿-拉夫逊优化算法(NRBO)的优化模型,建立声发射震级-频度关系b值、活跃度S值及破裂类型RA-AF值等多元参量与煤体裂纹扩展状态的对应关系,通过开展煤体破坏声发射监测试验,得到声发射多元信号数据,并以此作为训练样本,利用NRBO-XGBoost模型对不同加载速率下煤体的裂纹稳定扩展(Ⅲ)和不稳定扩展(Ⅳ)阶段进行智能识别,实现XGBoost参数的自适应寻优,采用准确率、精确率、召回率及F1值4项指标评估各模型的性能。【结果和结论】 研究表明:(1)在Ⅲ阶段,煤体b值和S值均小幅度升高,剪切裂纹所占比例减少,进入Ⅳ阶段后,b值和剪切裂纹占比呈相反变化趋势,S值大幅度升高;随着加载速率增加,b值波动水平和幅度均降低、S值升高水平减小、剪切裂纹所占的比例增加水平增大。(2)建立的NRBO-XGBoost模型实现了由声发射多元参量到煤体裂纹扩展状态的智能识别。(3)同XGBoost和PSO-XGBoost模型的4项评估指标对比,NRBO-XGBoost模型下低和高加载速率样本分别达到90.69%、88.79%、99.00%、93.62%和82.76%、86.76%、88.50%、87.62%,效果最优。研究成果为声发射技术在煤体裂纹扩展状态识别与智能监测研究提供了新的思路,利用实测声发射数据建立预测模型,可实现煤岩动力灾害的监测、预警。

     

    Abstract: Objective The complexity and uncertainty of coal rock dynamic disasters are closely related to coal rock damage. Accurately identifying the propagation state of coal rock cracks is an important way to study their instability and failure. Currently, the identification methods based on acoustic emission physical quantity information have problems such as slow speed and low efficiency, which are difficult to meet the safety, efficiency, and intelligent mining needs of coal mines. Methods To achieve intelligent recognition of coal crack propagation status, an optimization model based on Newton Raphson optimization algorithm (NRBO) was constructed using distributed gradient boosting library (XGBoost). The corresponding relationships between multiple parameters such as acoustic emission magnitude frequency relationship b value, activity S value, and fracture type RA-AF value and coal crack propagation status were established. By conducting coal damage acoustic emission monitoring experiments, acoustic emission multiple signal data were obtained and used as training samples. The NRBO XGBoost model was used to intelligently recognize the stable (Ⅲ) and unstable (Ⅳ) stages of coal crack propagation under different loading rates, achieving adaptive optimization of XGBoost parameters. Accuracy, precision, recall, and F1 value were used to obtain the acoustic emission multiple signal data. Evaluate the performance of each model using four indicators. Results and Conclusions Research indicates that: (1) In stage Ⅲ, both the b value and S value of the coal body increase slightly, and the proportion of shear cracks decreases. After entering stage Ⅳ, the b value and the proportion of shear cracks show opposite trends, and the S value increases significantly. With the increase of loading rate, the fluctuation level and amplitude of the b value decrease, the increase level of the S value reduces, and the increase level of the proportion of shear cracks increases. (2) The established NRBO-XGBoost model achieves intelligent identification of coal crack propagation states from mul-tiple acoustic emission parameters. (3) Compared with the four evaluation indicators of the XGBoost and PSO-XGBoost models, the NRBO-XGBoost model achieves the best results, with low and high loading rate samples reaching 90.69%, 88.79%, 99.00%, 93.62% and 82.76%, 86.76%, 88.50%, 87.62%, respectively. The research results provide a new idea for the identification and intelligent monitoring of crack propagation in coal by using acoustic emission technology. By establishing a prediction model with the measured acoustic emission data, the monitoring and early warning of coal and rock dynamic disasters can be achieved.

     

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