Study On Cause Of Formation And Mechanism About Ground Fissure Of Weihe Basin

Internal and outer force make the rock and soil mass be out of shape, when it exceeds the internal cementing property, the rock and soil mass burst, their continuities are destroyed, and then, the ground fissures appear. Ground fissure scourge being a new, unaided natural disaster is being paid close attention by international earth sciences community. Since 20^th, specially after Tangshan Earthquake, 1976, 196 ground fissures appear in more than 20 counties and cities of Weihe basin. The extremely intense geo-hazards which needed to be systemic study occur in the Weihe basin, in which the crustal motion continually appearing. During my proceeding to Master degree, I have the honor to take part in the "Study on Ground Fissure Hazard of Weihe basin". Through the investigation and study, we have found out the distribution of the ground fissures in Weihe basin, have taken apart the cause of formation about them, and hope that it will be reference for further study and its prevention and mitigation hazard.Firstly, according to the spot investigation, we have cleared up the present distribution and character about the ground fissure of Weihe basin. The ground fissures exist around the active faultage, and they are unanimous in trend with the faultage, which is determined by the consistency of their tectonic environment, mechanical cause of formation and stress field.Secondly, we summarize the cause of formation about the ground fissures lying in every counties and cities, and analyze their principal factor and influencing factor. According to the study about the survey data, the formative factors about ground factor in Weihe basin lie: tectonic activities which include geostress, seimogenic activity and tectonic joint of ground itself; inducing factors which consist of false side slope, false reservoir, excessive coal mining and groundwater mining, explosion and mechanical vibration, factors of the weather and the ground itself, and the inducing factors mainly concentrate on the influence of the loess collapse and aggravation, the surface water makes to the ground fissure hazard.Lastly, tectonic mechanism about the ground fissure of Weihe basin is analyzed based on the research results of ancestors'. Two examples, which include the fissure caused by the excessive groundwater mining and by the coaction of the faultage activity and coal mining ,are chosen to do finite element simulation and analysis, so as to ulteriorly show the mechanism of the ground fissure of Weihe basin.