Study On Formation Mechanism Of Ground Fissure Under The Action Of Fault Movement And Groundwater

Ground fissure is a surface rupture phenomena induced by the internal and external dynamic geological processes,human activities and other factors,which is one of slowly-developed geological disasters.Since 1920 s,Gaoliying has developed increasingly serious ground fissure disasters and become the most active ground fissure geohazard area in Beijing.As a ground deformation disaster,ground fissure has brought great trouble to Beijing city planning and development,the construction of ground road and underground rail transit,which has seriously restricted the sustainable development of economy and society in Beijing.Taking Gaoliying ground fissure in Beijing as research object,this paper studied the formation mechanism of ground fissure under the action of fault movement and groundwater based on the ground fissures in Gaoliying.Firstly,this paper described the regional geologic background of Gaoliying,including meteorological and hydrological characteristics,geographic and geomorphic co nditions,formation lithology,geological structure and hydrogeological conditio n.O n the basis of the existing research achivements,the development characteristics of ground fissures in Gaoliying were analyzed,including the general situation,activity characteristics and formation cause.Then,through the large-scale physical model test under the action of fault movement and groundwater,the development characteristics of ground fissures were revealed,including the characteristics of formation stress change,settlement of surface difference and crack propagation.Meanwhile,using the finite difference software FLAC3 D,the numerical model of fault dislocation and groundwater variation was respectively established,thestrata displacement and stress change laws were disclosed.The research results show that the development of Gaoliying ground fissure is controlled by Huangzhuang-Gaoliying fault belt,and over-exploitation of groundwater is the main factor of its paranormal activities.The contribution rate of fault movement to Gaoliying ground fissure deformation approximately accounts for 82.9%,and groundwater is about 17.1%.Therefore,it is concluded that Gaoliying ground fissure should be the interaction result of fault movement and groundwater.This above conclusions has an important guiding significance to the urban planning and construction of Beijing and the prevention and control of ground fissures.Meanwhile,it can also provide a reference for the prevention and mitigation of ground fissure disasters in urbanization in other areas.