Study On The Fracture Propagation Of Ground Fissures In Different Soil

Xi’an ground fissure disasters have a negative impact on the planning and development of the city with destroying builidings, cutting pipesd, broking pavement and subgrades etc.It results in a large amount of economic loss. Therefore studying the rupture propagation mode and omechanism of ground fissures can provide a theoretical basis for the disaster prevention. On the basis of previous studies, this paper has an important theoretical and engineering significance for the research and analysis of the rupture propagation mode and mechanism of the ground fissures in different soil conditions.Through the collection of regional geology and ground fissures survey data combined with ground survey, drilling and trenching achievements, this paper preliminary expounds the distribution, profile characteristics, motion characteristics, activity rate and influence width of ground fissures in Xi’an. Then systematically summarizes the rupture propagation models of ground fissures, and carries on the explanation from the view of fracture mechanics.Analysising influencing factors of crack propagation in ground fissure, such as structural factors,rainfall factors, pumping factor, rate of water content, degree of density, confining pressure and Joint fissures.Analyzes the rupture propagation of ground fissures in different soils by using discrete element software PFC2 D simulation.It is revealed that the existence of obvious fracture zone and surface tension cracks in the clay through comparing and analyzing the mode of crack propation in single clay layer and single sand layer. there is no obvious cracks in the sand layer. The surface subsidence is gentle slope shape in clay layer and The uneven settlement of the ground surface is in a steep ridge in sand layer. Changes of clay layer thickness have a significant effect on the expansion of the crack rupture while the sand layer thickness have little influence on crack propagation. There are no obvious fracture zones and tension fractures in ground surface when cracks in the soil and sand interbed propagate.