基于双层模态分解和Autoformer模型的矿井微震时序预测方法

Mine microseismic time series prediction method based on dual-layer modal decomposition and Autoformer model

  • 摘要: 在煤矿深层开采中,微震事件常作为矿井突水预警的重要信号。有研究表明,煤岩体在突水通道形成过程中会发生破裂并伴随微震活动,微震事件的准确预测对矿井安全至关重要。然而,传统深度学习模型如长短期记忆网络(Long Short-Term Memory,LSTM)和卷积神经网络(Convolutional Neural Network,CNN)在处理微震数据的非平稳性和复杂动态特征时存在一定局限性。为提升预测精度与泛化能力,提出一种基于双层模态分解和自相关分解Transformer模型的微震时序预测方法。首先使用改进的完全自适应噪声集合经验模态分解方法(Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise,ICEEMDAN)将原始微震数据分解成多个本征模态序列;然后,使用一致随机采样的方法对每个本征模态序列进行采样,计算其采样样本熵,并通过设置样本熵阈值将不同本征模态序列重构为高频、中频、低频3个序列;应用变分模态分解(Variational Mode Decomposition,VMD)分别对这3个序列进行处理,并计算不同分解个数下的中心频率以确定最优分解个数,得到微震数据的多元特征时间序列;最后,采用滑动窗口机制构造输入‒输出数据集,将一段时间内的多元特征时间序列作为输入,后一段时间内的微震数据作为输出,结合具有自相关分解的Transformer模型进行时序预测。基于张双楼煤矿某工作面的微震数据,对多种时序神经网络模型进行了对比研究。实验结果表明:所述模型在预测精度和模型稳定性方面具有显著优势。在单步预测中,模型能够准确预测微震能量强度的变化,测试集上的预测值与真实值拟合优度R2达到0.92,多步长预测中,模型能够较好地预测微震的演化趋势,在使用前24个步长预测未来12个步长时,真实值与预测值的拟合优度R2接近0.82。所提方法不仅提高了预测精度与稳定性,还为煤矿微震事件的科学管理与风险防控提供了新的技术支撑,为煤矿突水微震监测提供新思路,对智慧矿山建设具有重要意义。

     

    Abstract: In deep coal mining, microseismic events often serve as a critical signal for early warning of mine water inrushes. Studies have shown that coal rock masses experience fractures and microseismic activities during the formation of water inrush channels, and accurate prediction of microseismic events is crucial for mine safety. However, traditional deep learning models such as long short-term memory (LSTM) and convolutional neural network (CNN) have limitations in handling the non-stationarity and complex dynamic features of microseismic data. To improve prediction accuracy and generalization capability, a microseismic time series prediction method based on a dual-layer modal decomposition and autocorrelation decomposition Transformer model is proposed. First, the improved complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) is used to decompose the original microseismic data into multiple intrinsic mode functions (IMFs). Then, a consistent random sampling method is applied to each IMF sequence to calculate its sample entropy. By setting a sample entropy threshold, different IMF sequences are reconstructed into high-frequency, mid-frequency, and low-frequency sequences. Next, variational mode decomposition (VMD) is applied to process these three sequences, and the optimal number of decompositions is determined by calculating the center frequency for different decomposition numbers, resulting in a multi-feature time series of microseismic data. Finally, a sliding window mechanism is employed to construct an input-output dataset, where a multivariate feature time series over a period is used as input, and microseismic data from a subsequent period is used as output. The Transformer model with autocorrelation decomposition is then used for time series forecasting. Comparative studies are conducted on various time series neural network models using microseismic data from a working face in Zhang Shuanglou coal mine. Experimental results show that the proposed model has significant advantages in prediction accuracy and model stability. In single-step prediction, the model accurately predicts changes in microseismic energy intensity, with the prediction fitting the true values with an R2 of 0.92 on the test set. In multi-step prediction, the model effectively predicts the evolution trend of microseismic events, with the predicted values fitting the true values with an R2 of approximately 0.82 when predicting the next 12 steps based on the first 24 steps. The proposed method not only improves prediction accuracy and stability but also provides new technical support for the scientific management and risk prevention of coal mine microseismic events. It offers new insights into microseismic monitoring for water inrush in coal mines and has significant implications for the construction of smart mines.

     

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