Abstract: To improve the seismic resistance behavior of the soft-stratum of urban utility tunnel in strong earthquake areas,this paper takes the utility tunnel as the research object and studies,the shock absorption effect of the shock absorbing layer with different settings through finite difference software FLACD.The results show that compared with the condition without seismic measures,the maximum settlement of the condition with the bedding shock absorbing layer decreases by 1.61%,the maximum and minimum principal stresses decrease by 29.75% and 4.88% respectively,the maximum shear stress decreases by 18.49% and the minimum safety factor increases by 15.13%;the maximum settlement of the condition with setting a semi-ring shock absorbing layer decreases by 1.55%,the maximum and minimum principal stresses decrease by 34.12% and 18.06% respectively,the maximum shear stress decreases by 31.86% and the minimum safety factor increases by 18.33%;the maximum settlement of setting a full-ring shock absorbing layer decreases by 16.92%,the maximum and minimum principal stresses decrease by 61.04% and 28.84% respectively,the maximum shear stress decreases by 35.78% and the minimum safety factor increases by 32.46%.It can be concluded that the shock absorption effect of setting a full-ring shock absorbing layer is better than the cushion layer and the semi-ring layer.

Key words: soft stratum, urban utility tunnel, shock absorbing layer, setting mode, shock absorption effect