煤层底板隐伏导水通道水力层析识别技术

    Hydraulic tomography identification of concealed water-conducting channels in coal mine floor

    • 摘要: 煤层底板隐伏导水通道的识别及其渗流场模拟评估是矿井突(涌)水防治的关键。地球物理勘探技术可识别隐伏导水通道的空间结构分布,但其探测反演结果需借助经验公式转换为水文地质参数后方可用于底板含水层渗流场模拟,该方法存在水压模拟值与监测值吻合度欠佳的问题。水力层析技术利用水压监测数据直接反演含水层水文地质参数的空间非均匀分布,可有效识别导水通道,从而提高渗流场模拟的精度。为此,采用砂箱试验,基于钻孔微水试验分析了含导水通道岩溶含水层的水压波动特征,并利用监测数据开展了导水通道的水力层析反演识别与渗流场预测对比分析;进一步通过数值试验,研究了监测孔数量、激扰源数量以及物探先验地质信息对识别精度的影响规律。结果表明:导水通道内的水压波动曲线呈快速上升后振荡衰减的特征,而通道外的水压波动曲线整体表现为先上升后缓慢下降的单峰形态;距激扰源越近,水压波动峰值越大,反之峰值越小,且水压波动响应时间略有延迟;与储水系数反演结果相比,导水系数反演结果能更清晰地刻画导水通道的结构特征,前者空间分辨率较低;增加激扰源数量较增加监测孔数量更能显著提高导水通道的识别精度;若物探结果与真实导水通道结构差异较大,将其作为先验地质信息会明显降低水力层析的识别精度。

       

      Abstract: The identification of concealed water-conducting channels in coal seam floor and the simulation and evaluation of seepage field are the key to the prevention and control of mine water inrush. Geophysics exploration techniques can identify the spatial structure distribution of concealed water-conducting channels, and the inversion results need to be converted into hydrogeological parameters before they can be used for seepage field simulation of floor aquifers, however, the simulated values of water pressure are not in good agreement with the measured values. In hydraulic tomography, the spatial non-uniform distribution of hydrogeological parameters in the aquifer is directly inverted by the water pressure monitoring value to identify the water-conducting channel, which ensures the accuracy of seepage field simulation. Therefore, the sand box test was used to study the characteristics of water pressure fluctuation in karst aquifer with water passage based on borehole slug test, and the hydraulic tomography inversion identification of water passage and the prediction and comparison of seepage field were carried out according to the monitoring data, finally, numerical experiments are used to study the influence of the number of monitoring holes, the number of excitation sources, and the prior geological information of geophysical prospecting on the identification accuracy. The results show that the water pressure fluctuation curve inside the water-conducting channel presents the characteristic of a rapid increase followed by oscillatory attenuation, while the water pressure fluctuation curve outside the water conducting channel presents the unimodal distribution form of rise and then slow decline. The closer the distance to the source is, the larger the peak value of water pressure fluctuation is. The farther the distance is, the smaller the peak value of water pressure fluctuation is and the time of water pressure fluctuation is delayed. Compared with the inversion results of hydraulic conductivity which can roughly describe the structural characteristics of water channel, the spatial resolution of the inversion results of water storage coefficient is lower; compared with increasing the number of monitoring holes, the spatial resolution of the inversion results of water storage coefficient is lower, increasing the number of excitation sources can significantly improve the identification accuracy of water channel. If the geophysical results are quite different from the structure of the real water channel, the wrong geophysical results can be used as prior geological information, and it will significantly reduce the accuracy of hydraulic tomography identification.

       

    /

    返回文章
    返回