Abstract: Xi’an,with its complexity and specific geologic condition,is the most representative city in the world for its ground-fissure,and these brings newly problems for the construction of subway lines.How is the ground-fissure extending and its influencing scope,degree and so on,are urgent and earnest to be solved for the city subway construction.In order to look into the ground-fissure spreading mechanics reason and extending characteristic in loess,the authors incorporated large-scale physical simul...