基于自然电位的充填裂隙溶质运移特征试验研究

In order to describe the solute transport process and characteristics in the filling fracture, the solute transport test model of filling fracture was designed and manufactured. The solute transport tests under different flow velocity conditions were carried out. The solute transport characteristics in the filling fracture were studied and the internal solute transport process was described in detail combining with the real-time dynamic monitoring data of self-potential (SP) at different measuring points. The results showed that: 1）In the range of0.0733～0.9630mm/s, the permeability coefficient of the filling fracture was 1.85 mm/s, which was close to the permeability coefficient of the filled porous medium 1.79 mm/s, and the water flow complies with Darcy’s law; 2） When the actual average flow velocity was 0.247 mm/s, 0.431 mm/s, 0.661 mm/s, the peak solute concentration at the sampling point was 5.14 g/L, 5.50 g/L, 5.78 g/L, and the initial and peak solute arrival times were all reduced, with the initial arrival times of4640s,2640s, and1560s, and the peak arrival times of5480s,3360s and2040s, respectively. 3） Under the conditions of the actual flow velocity of the three kinds of water currents, the SP response showed similar characteristics during the solute transport. The absolute value of the SP peak at the measuring electrode was gradually reduced from 1^#to 6^#along the flow direction, and the steepness gradually decreased when the peaks came out in sequence. In addition, both the solute dispersion front and the solute dispersion peak concentration point were moving at a uniform speed with the flow of water, and the corresponding average initial flow velocity of the solute dispersion front were 0.214 mm/s, 0.396 mm/s, 0.685 mm/s, and the average flow velocity peaks corresponding to the solute dispersion peaks were 0.189 mm/s, 0.347 mm/s and 0.571 mm/s. 4） The actual average flow velocity based on the peak SP calculation was basically the same as the calculation result using the peak solute concentration, but the peak SP calculation result was closer to the actual average flow velocity (flow calculation result), and the accuracy was increased by 1.5%; as the flow rate continued to increase, the macro-average flow velocity error calculated from the peak SP was reduced by 9.9%. 5） The test showed that compared with the peak SP value, the macroscopic average velocity of the filling fractured flow calculated using the initial SP value was closer to the macroscopic average velocity of the flow calculated from the flow data.