基于距离加权约束算法的围岩三维电阻率CT反演成像研究  

3D cross-hole resistivity inversion imaging of surrounding rock based on distance weighting constraint algorithm

作　　者：刘征宇[1] 李术才[1] 刘斌[1] 范克睿 聂利超[1] 张欣欣[1] 

机构地区：[1]山东大学岩土与结构工程研究中心,山东济南250061

出　　处：《岩土工程学报》2017年第4期652-661,共10页Chinese Journal of Geotechnical Engineering

基　　金：国家重点基础研究发展计划("973"计划)项目(2013CB036002;2015CB058101);国家重大仪器设备研制专项(51327802);国家自然科学基金重点项目(51139004);国家自然科学基金面上项目(51479104)

摘　　要：孔中电极附近成像效果差的问题是一直以来困扰三维电阻率CT精细探测的难题,针对该问题,提出了"距离加权"约束反演的思路,通过构建"指数型"衰减的距离加权因子分布模型,对距孔中电源点不同远近的剖分单元赋予差异权重,重点改善了孔中电源点附近区域反演敏感度较高而造成的成像形态畸变问题,提高了三维电阻率CT反演成像方法对异常体三维定位和识别的精度及可靠性。通过数值反演试验和物理模型试验研究,进一步检验了距离加权约束反演方法在改善孔中电极附近异常体成像形态方面的有益效果,试验结果均比较准确地反映了异常体的空间位置、规模和形态。Aiming at improving the inversion quality of anomalies near the electrodes in boreholes, which has been a large issue interfering in the three-dimensional（3D） cross-hole electrical resistivity tomography（ERT）, an inversion method based on the distance weighting constraint is proposed. Different weighting coefficients are assigned to different meshes in the model according to the distances away from the current points in the boreholes, and the computed exponential decay distribution model is established. Under this treatment, the image shape distortion problem of anomalies near the current points in the boreholes resulting from high inversion sensitivity is suppressed, and the resolution of 3D location and reliability of recognition of anomalies by the 3D cross-hole resistivity inversion method is improved. The effectiveness of the distance weighting constraint inversion is further tested and verified through numerical inversion examples and physical model tests. The distribution characteristics such as the spatial location, scale and shape of the anomalies are reflected accurately in the test results.

关 键 词：三维电阻率CT 反演成像 距离加权约束 

分 类 号：TU43[建筑科学—岩土工程]