跨孔电磁波层析成像在岩溶三维空间分布上的应用

Application of Cross-hole Electromagnetic Wave Tomography in Three Dimensional Spatial Distribution of Karst

灰岩地区岩溶发育对城市建设有着极大的威胁,一般岩溶探测主要采用钻探勘探,很难充分反映地下岩溶发育规模与特征,而跨孔电磁波层析成像方法,能查明工区地下岩溶发育及延伸情况。对钻孔间地层进行电磁波层析成像正演,表明电磁波层析成像对岩溶勘察的准确性与可行性。结合地铁轨道交通岩溶勘察实例,应用电磁波层析成像技术反演电磁波吸收系数二维成像与三维成像。通过获取不同深度与水平空间的吸收系数切片,重建地下溶洞三维空间形态,为重大工程岩溶探测建设提供详细的资料。

Karst development in limestone areas holds great potential hazards to the urban construction,Using the conventional way of drilling,it is difficult to fully identify the characteristics and scale of underground Karst development in urban Karst exploration while cross-hole electromagnetic wave tomography can find out the state of development and extension of underground Karst in the work area.The forward electromagnetic wave tomography which is performed on the boreholes indicates the accuracy and feasibility of electromagnetic tomography for Karst investigation.Based on the examples of Karst exploration in metro rails,the electromagnetic wave tomography is applied,thus the two-dimensional absorption coefficient and the three-dimensional absorption coefficient images are retrieved respectively.By obtaining the absorption coefficient slices of different depths and horizontal spaces,the 3D spatial form of the underground Karst cave can be reconstructed,and detailed data for Karst exploration in construction of major projects can be provided.