The Discussion On The Genesis Mechanism Of Earthquake Ground Fissures In Weihe Basin

Weihe Basin is a typical tensile faulted basin,located at the junction of tectonic units in China,is one of the places with intense seismic activity in China,the Weihe Basin is also the hardest disaster area of geological hazards in China,and under this geological background,there may be a certain relationship between seismic activity and fissures in the basin hinterland.Therefore,combining with the project of geological disaster investigation of Weinan area in Guanzhong Basin,this paper investigates the fissures in Weinan area in the east of Weihe basin,and works with the data of ground fissures in Weihe basin to find out the geological background environment for the development of seismic ground fissures in Weihe basin.Based on the analysis of the history of Weihe basin and the current seismic statistics,this paper summarizes the characteristics of seismic activity in Weihe Basin,analyzes and summarizes the development characteristics of seismic ground fissures in Weihe basin through the development characteristics of seismic ground fissures in typical areas,and carries out numerical simulation with FLAC3 D program to discuss the Genesis mechanism of seismic ground fissures in Weihe basin.Through these efforts,the following results have been achieved:1.Through field investigation,it is found that the fissures in Weinan area are mainly distributed in Dali County territory,the ground fissures are controlled by topography,geomorphology and fracture activities,mainly along the NNE and Near East-west development,the overall CIS unit is associated with structural faults,and the boundary fissures in the geomorphological units are more developed,and the local fissures in the geomorphological units are more developed.2.Seismic activity in Weihe Basin has significant spatiotemporal distribution characteristics and strength characteristics.In time,the seismic activity of Weihe Basin is periodic,the period length is about 300-600 years,the spatial distribution shows the frequent seismic activity in the east of Weihe Basin,the west is weak,the earthquake activity of historical earthquake is frequent,the current seismic activity is small,and the current earthquake activity in the basin is dominated by small earthquakes.3.The seismic ground fissures in the Weihe basin are mostly associated with the active faults,and the activity of the historical fissures is in good agreement with the seismic activity cycle.Through field measurement and data analysis,it is concluded that the development characteristics of seismic ground fissures in Weihe Basin are similar,and the probe profile shows that the ground fissures in the seismic action are densely developed on the fault plate,the fissures are approximately upright,the secondary fissures are mostly hidden in the renewal system of the underground 4~5m and the early Holocene strata,and the time characteristics of the tectonic activities are.4.Numerical simulation results show that the activity of the hidden fracture under the action of regional tensile stress will be enhanced,gradually extending to the surface,the upper disk near the fracture 50 m range,the lower disk near the fracture 30 m range of the surface is the dangerous area of ground crack development,under the action of seismic activity,hidden fracture will affect the continuity of seismic wave propagation,The displacement envelope will be produced in the upper and lower plates within a certain range of underground,and the envelope will shift to the surface under the influence of regional tensile stress after the earthquake.Through the analysis,it is concluded that the underground displacement envelope may be the area of seismic ground crack development.