Numerical simulation and exploration test for water from the floor strata of coal mining face using dual frequency induced polarization method
HU Xiongwu, XU Biao, ZHANG Pingsong, WU Rongxin,FU Maoru,CHENG Lin
深部煤层开采常遭受底板水害威胁,严重影响煤矿安全高效生产。 采用矿井电法实施采场 底板岩层富水性探测是煤矿水害防治工作中的一项重点内容,但该方法面临实测电阻率多解性强 及异常定位不准的难题。 为进一步提高对岩层富水区的判定精度,提出了采煤工作面双频激 电(Induced Polarization,IP)全方位探测方法。 结合淮南矿区深部 A 组煤层顶底板地质与地电条 件,构建了不同方位的圆柱体富水异常地电模型;以 Cole-Cole 模型为激电效应基础,采用有限元 方法实施了双频激电数值模拟,理论分析了不同异常模型的激电视参数响应特征,其结果表明: 1 单巷激电视参数表现为低阻高频散异常,曲线“交点”可准确定位异常模型的走向位置,但难以 确定异常模型的准确方位。 2 双巷透视各发射点对应的激电视参数曲线在异常模型附近聚焦,同 样表现为低阻高频散异常特征,发射点与异常模型的位置关系决定了视参数曲线形态及性质,接收 点与异常模型的位置关系决定了异常幅度大小。 激电视参数对面内及巷道底板异常模型的响应幅 度大,对面外模型异常响应幅度偏小。 为进一步评价激电视参数成像精度,对比分析了双巷透视和 全方位数据的三维反演结果,表明单巷测深和双巷透视数据可相互约束,利用全方位方法所得的激 电反演结果能精准定位各异常模型,体现了该方法的优越性。 工程实践进一步表明,该方法能有效 降低电性异常的多解性,大幅提高异常空间定位精度,改善煤层底板岩层富水区的判定效果,为煤 矿水害精准防治提供了有力的技术支撑。
Deep coal seam mining is often threatened by water damage under the floor,which seriously affects the safe and efficient production of coal mines. Using mine electrical method to detect the water abundance of floor strata is an important way in the prevention and control of water disasters in coal mines,but this method faces the problems of strong multi solution of measured resistivity and inaccurate positioning of anomalies. In order to further improve the detection accuracy of the water rich area of the rock strata,an all around dual frequency induced polarization (IP) method for the coal mining face was proposed. Combined with the geological and geoelectric conditions of the roof and floor of deep group A coal seams in the Huainan mining area,the geoelectric models of the water rich cylinders in different directions were constructed. Based on the Cole-Cole model,the numerical simulation for the dual frequency induced polarization field was carried out by using the finite element method,and the response characteristics of IP parameters of different anomaly models were analyzed theoretically. The results show that ① The apparent parameters of IP in a single roadway show low resistivity and high frequency dispersity. The intersection point of the curves can accurately locate the strike position of the abnormal models,but is unable to determine its orientation exactly. ② The curves of apparent parameters of IP corresponding to each transmitting point in the double roadway are focused near the abnormal model,and also show the abnormal characteristics of low resistivity and high frequency dispersity. The position relationship between the transmitting points and the abnormal models determines the shape and properties of the apparent parameter curves,and the position relationship between the receiving points and the abnormal models determines the amplitude of apparent parameters. In which,the apparent parameters amplitude responded by the abnormal model lied in the working face or roadway floor is larger than that lied outside of the working face. In order to further evaluate the imaging accuracy of the apparent parameters of IP,the three dimensional inversion results of perspective and all around data in the double roadways were compared and analyzed. The results show that the sounding data obtained in single roadway and perspective data obtained in the double roadways can be mutually constrained,and the inversion parameters of IP obtained by the all around method can be used for positioning the abnormal models accurately,which demonstrates the superiority of this method. The engineering practice further shows that this method can effectively reduce the multiple solutions of electrical anomalies,and greatly improve the spatial positioning accuracy of anomalies and the accurate determination effect of water rich areas of coal floor strata,which provides a strong technical support for the accurate prevention and control of coal mine water disaster.
coal mining face;floor water;dual frequency induced polarization method;numerical simulation
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会