Slope Response In DC Resistivity Model By Using Three-dimensional Finite Element Method

With the development of economy, we encountered Slope's instability in geological disasters is an increasingly prominent problem. No matter what kind of slope, before excavation or filling, slope did not exist the sliding surface, even if the existence of neither weak or soft sandwich structure, nor can regarded as the sliding surface, as they there are no sliding trend. This is precise difference between the slope and the landslide. The absence or non-existence of the actual sliding surface in the slope, therefore, we can not easily identified through methods such as drilling, so used geophysical methods to exploration slope, analysis and identification of potential sliding surface become one of the possible.However, due to the unique topography of the slope so that the current market distortion, the apparent resistivity curves significantly affected in Resistivity exploration, the measured data will not be able to deal with in sometimes . In order to enhance the efficiency and make full use of the result of field work, it must be the correct processing and interpretation of these field measurements. So we must understand the theoretical analysis and case-specific topographical features of abnormal distortion, and then the result of interpretation may be consistent with the geological characteristics.This paper studied the stability current field equations, derived the boundary value problem in the three-dimensional space, converted the corresponding boundary value problems into variational problems, derived variational equation; Then based on the finite element method for solving a standardized process, to discrete solution region into a large number of high-precision Three-dimensional isoparametric hexahedron element; Classified the elements to avoid double counting in the same elements, which greatly speed up the assembly process of the overall stiffness matrix. Used Iccg to decompose large-scale of sparse matrix, obtained power at all nodes corresponding to the potential; Based on current market stability can be superimposed, use single point source of potential through a combination can be calculated apparent resistivity of different devices, and thus complete the forward calculation. Use the result of Horizontal layered model by itself the analytical solution to verify whether the correct procedures of forward modeling that use in this paper, the result show that the error of the appropriate range.Then the paper discussed the issue of Terrain slope impact on the DC apparent resistivity. Use Schlumberger transverse profiling method, and correct the Impact of topographic on the slope by the contrast method to analyze the problem of terrain impact on the classic type of terrain like slope. To draw a conclusion from the paper, The topographic effect on the overall slope, the deep of slope toe was relatively low resistance; because the right side of corner of sloping roof was plane, less affected by terrain; The deep of corner of sloping roof is relatively high resistance; Topographic will take away useful abnormal on thin low-resistivity body. Tilted stratum impacted by the deep of slope toe that was low resistances, so that the left side interface of anomalies was not clear. The offset of tilted stratum Related with the thickness of stratum, Dip Angle of stratum and Differences in rock properties. When the greater the Dip Angle of stratum and the greater Differences in rock properties, the level which was formed in the cross-section of the apparent resistivity was clearer. When the greater thickness, the level of the left side was clearer and the offset was not obvious. Topographic effect of the corner of sloping roof was greater than the slope toe's.Terrain makes the impact of sections of apparent resistively greater distortion, and some have been difficult to identify. By the terrain correction, the anomaly in the apparent resistively sections more clearly, only a few difficult to identify physical location of anomalies. Thus draw some conclusions, in order to provide some reference to other researchers.