Research on dynamic response characteristics of typical ground fissure sites in Hebei Plain

Ground fissures in the Hebei Plain are widely distributed and cause severe disasters, seriously impacting local engineering construction and people’s life. The research on ground fissures in the Hebei Plain focuses mainly on the development characteristics, genesis mechanism, and distribution. However, there is little research on the dynamic characteristics of the site in this area. In order to study the influence of ground fissures on the dynamic response of the site in the Hebei Plain, this study conducted microtremor testing on typical earth fissures caused by tectonics, earthquakes, and ancient rivers. It determined the dynamic response characteristics of earth fissure sites of different origins by the Fourier amplitude spectrum, response spectrum, and Arias intensity. The results show that the ground fissures have a small impact on the predominant frequency and predominant period, but have a great influence on the dynamic response strength of the site. Furthermore, the dynamic response has an amplification effect near the fissure, which increases to 2.2-2.7 times on the hanging side and 1.7-2.4 times on the heading side. It gradually declines with the increase of the distance from the fissure and finally stabilizes. The amplification effect is greater on the hanging side. The influence of different types of ground fissures on the dynamic response of the site is basically the same, but the influence range is different. The tectonic fissure has the largest amplification effect, about 24 m, the seismic fissure is the second, about 22 m, and the paleochannel fissure is the smallest, about 20 m. After full consideration, the ground fissures influence the dynamic response of the site out to about 24 m on the hanging side and 20 m on the heading side. The amplification effect and the range of influence can provide a reasonable seismic fortification basis for the engineering structure of the ground fissure site.