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目的将电阻率层析成像应用于探测潜伏断层的研究中,本文发现了断层和地下水的一些基本电阻率分布特征,这对于工程物探意义重大。一般情况下,断层两侧具有不同的电阻率特征。但是,根据电阻率层析图像中的电阻率分布,通常难以区分断层和地下水层,这是因为两者不仅都具有低电阻率值,而且还具有非常相似的电阻率异常特征。资料和方法运用电阻率层析图像的数据,电阻率层析图像中的断层会呈现如下特征:1)由于孔隙度的加大和地下水的存在,使得断层表现出高角度的低阻线性结构。它们既可以出现在浅部盖层中,也可以存在于深部基岩中。特别是在深部区域,它们尤为明显;2)它们还呈现出高角度的线性梯度带,在该梯度带两边的电阻率结构出现整体性的差异。通常情况下,正断层的上盘表现出低阻或/和班驳状的高阻和低阻扰动区,而下盘则为完整的高阻区,这与逆冲断层正好相反;3)与断层有关的电阻率异常区常常具有良好的大尺度水平连续性,并且可以追踪异常区附近的精细电性结构。而地下水的电阻率特征为:1)如果没有裂隙,地表水所引起的低阻区非常浅,即使存在丰富的水源以及高孔隙度的砾岩和中粗砂。一般情况下,其底端深度不超过强风化区;2)地下水的电阻率值非常低,特别在高矿化度的地区。地下水,包括岩溶水和砂岩水,的电阻率?
Aim To apply resistivity tomography to the investigation of latent faults, some basic resistivity distributions of faults and groundwater were found in this paper, which is significant for engineering geophysical prospecting. In general, the fault has different resistivity characteristics on both sides. However, based on the resistivity distribution in resistivity tomographic images, it is often difficult to distinguish between faults and groundwater because both have not only low resistivity values, but also very similar resistivity anomalies. DATA AND METHODS Using resistivity tomographic image data, faults in resistivity tomography images show the following characteristics: 1) Due to the increased porosity and the presence of groundwater, the faults exhibit high-angle, low-resistivity linear structures. They can occur in shallow cap rocks or in deep bedrock. They are especially noticeable in deep regions; 2) They also exhibit high-angle linear gradient bands with a holistic difference in resistivity structures on either side of the gradient. Normally, the upper plate of the normal fault shows low resistance and / or banded high resistance and low resistance disturbance zones, while the lower plate is the complete high resistance zone, which is exactly the opposite of the thrust fault. 3) The associated resistivity anomalous regions often have good large-scale horizontal continuity and can trace the fine electrical structures near the anomalous regions. The resistivity of groundwater is characterized by: 1) Without fissures, the low resistivity zones caused by surface water are very shallow, even with abundant water sources and high porosity conglomerates and coarser sand. Under normal circumstances, the depth of its bottom does not exceed the area of strong weathering; 2) the value of groundwater resistivity is very low, especially in areas with high salinity. Resistivity of groundwater, including karst water and sandstone water?