物探技术结合机器学习方法在垃圾填埋场渗漏点调查中的研究

    Investigation of landfill leakage points using geophysical exploration and machine learning methods

    • 摘要: 垃圾填埋场中堆体的压缩沉降可能会致使生活垃圾处理场渗滤液收集管道的变形失效,进而使得防渗层发生破裂,垃圾渗滤液发生泄漏。监测渗滤液防渗层损伤的主要方法包括:从填埋场采集水土样本、通过室内化学分析确定污染物含量和地面地球物理勘探工作。基于上述传统环境地质勘探方法,本文采用地理信息系统(geographic information system,GIS)技术结合机器学习方法和影响因子预测法,实现了对填埋场渗滤液泄漏的有效预测。首先,以5 m×5 m的网格分辨率对填埋场区域进行网格划分,并为每个网格单元分配对应位置坐标信息,通过机器学习方法建立人工神经网络(artificial neural network,ANN)模型来预测填埋场渗漏点。基于对华北某填埋场的实地调查,选取了880个测试样本和220个验证样本。将地下水深度、电阻率、极化率、雷达反射波形同相轴是否异常、同相轴与邻近监测孔位置的关系以及半衰期信息作为输入因子,输出结果为各网格单元的渗漏概率。比较了BP神经网络和RBF神经网络两种机器学习方法的预测结果。结果表明:BP神经网络模型具有较好的预测效果,地下水位深度、电阻率及电阻率与监测孔位的关系对不透水膜渗流概率的预测影响最大。将每个影响因子的后验概率叠加,得到了预测模型对渗漏风险区域等级划分图,达到对填埋区的渗滤液渗漏风险分级监控的目的。

       

      Abstract: The compression and settlement of waste deposits in landfills may cause the deformation failure of leachate collection pipelines in municipal solid waste treatment facilities. This failure will further lead to the rupture of the impermeable layers and subsequent leakage of landfill leachates. Primary methods for monitoring damage to leachate impermeable layers include: laboratory chemical analysis of the pollutant levels of soil and water samples from landfills, and surface geophysical exploration. Building upon the above traditional environmental geological exploration methods, this study achieved effective prediction of landfill leachate leakage using geographic information system (GIS) technology combined with machine learning and influencing factor prediction. Specifically, the landfill area was divided into grid cells with resolution of 5 m × 5 m, which were then assigned corresponding spatial coordinates. A machine learning approach was employed to establish artificial neural network (ANN) models for predicting landfill leakage points. Based on a field investigation of a landfill in North China, 880 test samples and 220 validation samples were selected. The data obtained from these samples, including groundwater table depth, resistivity, polarizability, anomalies of seismic events in radar reflection waveforms, spatial relationships between seismic events and adjacent monitoring boreholes, and half-life information, were used as the input for the models. The output provided the leakage probabilities of all grid cells. Finally, the prediction results of two machine learning methods, the backpropagation (BP) and radial basis function (RBF) neural networks, were comparatively analyzed. The findings indicate that the BP neural network model showed higher prediction performance. The groundwater table depth, resistivity, and the relationship between resistivity and monitoring borehole positions served as the dominant factors influencing the seepage probability prediction of the impermeable layer. By superimposing the posterior probabilities of various influencing factors, the prediction model generated a classification map for leakage risk zones, achieving the objective of graded monitoring of leachate leakage risks within the landfill area.

       

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