煤层底板导水裂隙演化规律的电法探测研究

RESEARCH ON ELECTRICAL PREDICTION FOR EVALUATING WATER CONDUCTING FRACTURE ZONES IN COAL SEAM FLOOR

通过试验测定不同岩样在充水条件下应力–应变全程电阻率的变化,给出在采动过程中煤层底板岩层产生导水裂隙时的导电性变化规律,并以此为基础建立底板采动导水裂隙带动态演化地电模型。利用三维电法正演软件对此地电模型进行正演数值模拟,得出煤层底板导水裂隙演化过程中的视电阻率响应特征,为矿井电法数据采集系统设计和资料处理解释提供理论依据。依据全空间高精度三维电法测量的思想,提出煤矿底板导水裂隙带动态监测系统的设计原则和技术要求,为现场实际工作条件下煤矿底板破坏裂隙带动态监测系统设计提供依据,并成功用于安徽一矿底板破坏导水裂隙带演化规律的探测。实测结果表明,采用三维电阻率法探测(监测)底板导水裂隙带演化过程效果明显,能显示出底板在回采过程中变化破坏情况,有利于煤矿底板突水预测和突水防治措施的制订。

In the experiment, the variation in resistivity of different rock samples during the complete stress-strain process under the water-filling condition is studied; and the variation rule of conductivity of water conducting fractures formed in floor during the mining activity is obtained. In addition, the geoelectric model for dynamic evolution of mining induced water conducting fractures is constructed. From the numerical modeling with 3D electrical resistivity software, the response characteristics of apparent resistivity of water conducting fractures in coal seam floor are achieved, which can provide a theoretical basis for designing the data acquisition system and data processing. Based on the theory of full-space high-accurate 3D electrical resistivity method, the principles and technical requirements for designing the dynamic monitoring system of water conducting fractures are put forward, which have been successfully used in a certain coal mine in Anhui Province. The result shows that the application of 3D electrical resistivity in detecting the evolution of water conducting fractures in coal seam floor is effective; and it can present the failure mode of coal seam floor in mining process; so it is quite favorable for schemes of predicting and preventing water inrush from coal seam floor.