Characteristics of disaster-affected bodies and influence factors for earth fissure in Beijing Plain

In the investigation and monitoring, it is found that the forms of the ground fissure disaster body in the Beijing plain area are different and are of remarkable regional characteristics. This paper aims to reveal the formation process and guide the prevention work of the earth fissures. Two typical ground fissures, namely the Songzhuang fissures and Gaoliying fissures, are selected in this study. The morphological characteristics of the Songzhuang and Gaoliying fissures are investigated, including the affected bodies, profiles, depths and activity aspects. The different morphological characteristics of the occurrence for the Songzhuang and Gaoliying fissures are analyzed based on varieties factors. The results indicate that (1) the affected body of the Songzhuang fissure exhibits obvious tensile deformation, the fissures extend vertically in trench. It is not in contact with the buried faults. The fracture affected body of the Gaoliying fissure shows obvious vertical dislocation and shear, and it extends with zigzag feature in trench, and offsets the strata. It is compounded with the buried faults. (2) The level morphological characteristics of the ground fissures are influenced by the earthquake and the regional stress field, and the morphology of the ground fissures in Songzhuang is reshaped by concentration of tensile stress, which were developed by the horizontal movement of soil mass caused by groundwater overdraft. The Gaoliying ground fissures inherits the morphological characteristics of the Huangzhuang-Gaoliying fault, and differential settlement in the small area accelerates the development of the Gaoliying fracture. (3) Groundwater exploitation is the main factor affecting the Songzhuang fissures. Groundwater exploration should be reduced for prevention and control of the ground fissure. Both the buried faults and groundwater exploitation are the main factors for the developmennt of the Gaoliying crack. For prevention and control of the ground fissure, decline in groundwater levels should be limited, real-time monitoring of the fault activities is needed , and an effective warning and forecasting system is established.