Study On The Ground Fissure In The Loess Area Of Fen-wei By Fine Multi-wave Seismic Exploration And Application

Ground fissure is a kind of supergene geological disaster phenomenon. Ground fissureis not only caused distress on people’s lives, but also lead to great damage on naturalenvironment. The ground fissure will directly influence the process of the development ofthe national economy, for example, the production engineering construction in industry andagriculture, urban planning and land utilization. So, ground fissure become an urgentproblem in urban and rural geological environment.This paper discusses the basic theory and method of shallow multiwave fine seismicdetection on the background of Fen-wei basin ground fissure, which based on the generalgeological characteristics and laws of ground fissure formation and distribution in loess area.At the same time, discusses other method and technique, respectively are seismic wave fieldforward modeling and inversion, first break wave velocity tomographic processing andinterpretation techniques, reflection wave processing and interpretation techniques, firstbreak and reflected wave joint inversion processing and interpretation techniques, seismicattribute extraction technology as long as shallow3D seismic data velocity tomographicprocessing and interpretation techniques. In addition, according to developmentcharacteristics of common ground fissures in Fen-wei area, the writer builds thecorresponding theoretic geological model. By forward and inversion simulating andimaging the full wave field, attribute extraction technique and actual data comprehensiveinterpretation and analysis, we can see that the forwarding and inversion results areconsistent with theoretical model. The abnormal variation characteristics in ground fissuresand fault of the reflected wave filed can be listed as follow, wrong event segment,waveform disorder, developed diffracted wave and wave field energy mutation and so on.The abnormal characteristics in fault and fissure of first break wave velocity tomographicinversion profile are partial high and low velocity anomaly in vertical and horizontaldirection. Abnormal characteristics of attribute body wave field are the mutation of relative attribute values between adjacent channels.Through analyzing actual ground fissure data we can found that in reflected P-waveand S-wave exploration result, the location of fissure and fault are basically identical. Butbecause of the P-wave and S-wave has different propagation rules in the medium, leading todistinct difference in velocity tomographic inversion profile stratification results. Byanalyzing the seismic data attribute we can see that the most-positive curvature, averageenergy amplitude attribute and coherent properties are sensitive to fissure and fault, and ithas the good auxiliary function in the process of data processing and interpretation. Firstbreak wave and reflected wave joint inversion can overcome the defect of single first breakwave only can consider the information above first wave impedance interface. And it canwell reflect the deep medium information and its inversion precision and effect are muchbetter than single first break wave inversion result.By researching the actual data we can find that the Fen-Wei basin has an obviousgeological structure characteristic, and the distribution of ground fissure has clear rule.Fen-wei basin ground fissure formed mainly because the geological tectonic activity and thegroundwater level change as the complementary. There are two major ground fissureformation models: one is Active fault associated type, and the other is the performance ofactive fault on the surface. And the ground fissure in longitudinal direction show thecharacteristics of the growth fault.