Seismic stability of a loess tunnel under the action of train

Abstract

ABSTRACTIn this paper, dynamic finite element static strength reduction method is used to obtain safety factor and plastic strain nephogram of loess tunnel structure with different thickness of covering loess under the combined action of train vibration load and a near-field earthquake with pulse, near-field earthquake without pulse or far-field earthquake without pulse. Finally, by analysing and comparing the variation rule of safety factor and the distribution scope of plastic strain, the stability of loess tunnel is studied. The results show that the tunnel safety factor with different thickness of covering loess is the largest under near-field earthquake with pulse, the second under near-field earthquake without pulse, and the smallest under far-field earthquake without pulse. Under the same earthquake action, the safety factor of tunnel structure increases with the increase of the thickness of covering loess, and the variation range of safety factor about loess tunnel with different thickness of covering loess is basically unchanged under the same earthquake action. In addition, the critical plastic strain is symmetrically distributed on both sides of the tunnel vault and arch feet, and the arch feet appear the maximum value, which belong to the weak parts.