基于BP–KAN的钻孔电阻率反演成像方法与应用

BP-KAN-based inversion imaging for borehole resistivity method and its application

  • 摘要:
    目的 在煤层采动造成围岩变形破坏监测中,由于钻孔电阻率法是动态的、三维全空间测量,其优势明显。然而,该方法传统的电阻率反演计算多采用最小二乘法反演方法,其成像精度难以满足实际工程需求。近年来,神经网络反演展现出解决此类问题的潜力,但其性能仍待进一步提升。
    方法 为此,提出一种基于BP–KAN的钻孔电阻率反演成像方法,以实现对煤层底板变形破坏范围与深度的精准监测。首先根据煤矿典型地质条件,建立采煤工作面不同回采阶段的煤层底板变形破坏的地电模型,进行正演模拟,以构建用于训练与测试BP–KAN神经网络的数据集;随后将BP–KAN与KAN、BP神经网络及最小二乘法的反演成像结果进行对比分析;最后结合山西某矿3303工作面底板钻孔电阻率法实测数据,对BP–KAN神经网络的反演成像效果进行了工程应用验证。
    结果和结论 基于BP–KAN的钻孔电阻率反演成像方法能较准确地得到煤层底板破坏区范围、边界形态及电阻率变化特征,提高了钻孔电阻率法的反演成像精度。在工程应用中,该方法反演得到的底板破坏深度为15.5 m,与现场双端封堵分段注水试验测得的15.0 m的绝对误差仅为0.5 m,优于传统BP神经网络的反演得到的19.0 m结果,同时,反演揭示的底板破坏范围与实际采动破坏演化规律一致,该方法具有较高的监测精度与可靠性,可为煤层底板变形破坏的精准监测提供了一种新途径。

     

    Abstract:
    Objective  In the monitoring of coal seam mining-induced deformation and failure of surrounding rocks, the borehole resistivity method stands out due to its capacity for dynamic, three-dimensional (3D) full-space measurements. However, conventional resistivity inversion for the method is generally carried out using the least squares algorithm, leading to limited accuracy in practical engineering. In recent years, neural network-based inversion has demonstrated the potential for addressing this challenge, while its performance is yet to be further improved.
    Methods In this context, inversion imaging based on a back propagation-Kolmogorov-Arnold network (BP-KAN) was proposed for the borehole resistivity method, aiming to accurately monitor the range and depth of mining-induced deformation and failure of a coal seam floor. First, based on representative geological conditions of coal mines, this study constructed geoelectric models for mining-induced deformation and failure of a coal seam floor under varying advancement distances of a mining face. Forward modeling was then conducted to establish training and test datasets for the BP-KAN neural network. Subsequently, the inversion imaging results derived using the BP-KAN neural network were compared with those determined using the KAN and BP neural networks and the least squares method. Finally, in combination with the measured data derived using the borehole resistivity method from the coal seam floor of mining face 3303 in a coal mine of Shanxi Province, the inversion imaging performance of the BP-KAN neural network in engineering application was validated.
    Results and Conclusions  The BP-KAN-based inversion imaging for the borehole resistivity method enables accurate characterization of the ranges, boundary morphologies, and resistivity variations of the mining-induced failure zone in the coal seam floor, thereby improving the inversion imaging accuracy of the borehole resistivity method. In the engineering application, the proposed BP-KAN-based inversion imaging revealed a floor failure depth of 15.5 m, with an absolute error of merely 0.5 m against the failure depth (15 m) derived in the field through the segmented water injection with double-end sealing using a borehole. Besides, the proposed inversion imaging method outperformed the inversion using a traditional BP neural network, which yielded a failure depth of 19 m. Furthermore, the failure range revealed by the proposed inversion imaging method was consistent with the actual evolution patterns of mining-induced failure. Therefore, the BP-KAN-based inversion imaging for the borehole resistivity method features high monitoring accuracy and reliability, offering a novel approach for the precise monitoring of the deformation and failure of coal seam floors.

     

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