The dynamic amplification effect of a site with earth fissures: a case study in the Taiyuan Basin, China

Abstract

As a widespread geological hazard, the disaster development process of earth ssures is irreversible and di cult to control, which seriously affects the construction and safe operation of engineering facilities. However, few clear conclusions and special regulations have been given regarding the in uence of earth ssures on the dynamic response characteristics of a site and earthquake prevention and disaster reduction measures. Therefore, the microtremor was used instead of earthquake motions to reveal the dynamic response of a site with ssures. The earth ssures in the Taiyuan Basin, which exhibit a large amount of activity, were used as examples. In order to reveal the dynamic response from several aspects, four methods, including the Fourier spectrum, the horizontal-to-vertical spectral ratio (HVSR), the response acceleration, and the Arias intensity, were employed. The results show that the spectrum peaks increase sharply at an earth ssure and return to a stable value approximately 20-25 m away from the ssure, indicating that the earth ssures have an ampli cation effect on the dynamic response of the site.Additionally, a greater ampli cation occurs on the hanging wall of the earth ssure. The in uence range of the dynamic response of site can be divided into four areas. Suggestions on the seismic forti cation intensity and setback distances were also proposed. The ampli cation mechanism was summarized as the coupling of the changes in the soil properties caused by earth ssure activity, the catadioptric effect of the earth ssure interface, and the multiple ampli cations caused by secondary ssures.