| Ground fissure is a supergene geological disaster phenomenon, which distributes inmany countries. And its the frequency and scale is increasing year by year. As it directlyinfluence the ecological environment and destroy the engineering construction, now theground fissure has become a primary regional geological hazards.The key content in this thesis is to discuss the basic theory and method by studying theground fissures in Fen-wei basin based on the knowledge of the general geologicalcharacteristics and laws of the ground fissure in the loess area, which include fine reflectionp-wave detection technology, the first arrival and reflected wave velocity tomographytechnology and p-wave elastic parameter extraction technology. First, we build a modelaccording to the essential feature of the ground fissures in Fen-wei basin. And then do the fullwave field forward modeling, reflected wave imaging processing and primary wave inversion.The results show that there are obvious anomalies in the reflection wave field characteristicsand tomographic velocity field for a certain scale of fracture and fault. Especially, for theshallow ground fissures with small differences in longitudinal direction, the anomaly may beseen on the distribution characteristics of the fracture development zone.By analysing the two-dimensional shallow seismic fine detection result data, whichinclude reflection wave field imaging results, primary wave velocity tomography and theseismic attribute parameter extraction result, we found that the anomaly characteristics ofwave field and velocity field generating by the ground fissures are consistent with the theoryresults. What’s more, taking the form of sensitivity and resolution, shear wave field andvelocity field anomalies are more significant. The joint exploration results using both p-waveand s-wave indicate that he abnormal changes of the elastic parameters in the ground fissurezones are properly useful for the recognizing the ground fissure and determining thedevelopment zone and the vertical distribution characteristics.Comprehensive fine shallow seismic exploration results and geological survey dataanalysis show that,for the ground fissures in Fen-wei basin, its development and distribution features are mainly affected by the regional active fault. The changes in groundwater andsurface water are only the induction factors. There are two major ground fissure formationmodels: one is Active fault associated type, and the other is the performance of active fault onthe surface. And the ground fissure in longitudinal direction show the characteristics of thegrowth fault. |
