圆锥型瞬变电磁法在多年冻土勘探中的应用研究OA

Traditional transient electromagnetic method(TEM)has achieved significant results in permafrost exploration on the Qinghai-Tibet Plateau,but research on fine-scale detection under complex geological conditions remains insufficient.Maduo County in Qinghai Province,located in the Three-River Source region,features high altitude,cold climate,and frequent freeze-thaw cycles,making it a typical area with alternating distribution of permafrost and seasonal frozen ground.This study focuses on the alpine grassland area of Maduo County and employs the cone-shaped transient electromagnetic method(C-TEM)for permafrost detection research.Based on forward modeling of geoelectric models of permafrost in different degradation states,the capability of the cone-shaped TEM system in delineating permafrost layers has been confirmed.The simulation results clearly demonstrate the detection effectiveness of the upper and lower boundaries as well as the transitional boundaries of the permafrost layer.By systematically arranging 11 parallel survey lines to acquire TEM response data and combining borehole core analysis and geological data,the spatial distribution characteristics and physical parameters of permafrost in the area were studied.The research results indicate that the permafrost in the study area exhibits a zonal distribution,with thickness decreasing from north to south and a lower boundary depth of 35-45 m.Its distribution pattern is significantly controlled by regional fault structures and groundwater activity.The resistivity profile clearly reflects a three-layer structural character:the active layer,permafrost layer,and bedrock layer exhibit distinct resistivity differences,showing good correspondence with borehole and ground temperature data.In structurally complex areas,the integrated interpretation method of C-TEM combined with regional geological characteristics and hydrological information significantly improves the accuracy of permafrost boundary identification,providing a new geophysical detection approach for dynamic monitoring and change assessment of permafrost on the Qinghai-Tibet Plateau.