Research on Seismic Response Characteristics of Double-arch Tunnel-Slope in Shallow-buried Biased Loess
In this paper,combined with practical projects,on the basis of model test and numerical simulation verification,the dynamic response characteristics of double-arch slope tunnel system in shallow-buried biased loess under earthquake action is taken as the main research objective.The waveform of EL wave is selected to simulate earthquake action,and three-dimensional finite element model is established to analyze the difference of slope dynamic response before and after tunnel construction and the dynamic response law of tunnel system under different ground motion intensity.The results show that the slope acceleration amplification coefficient presents an obvious nonlinear change trend in the steep slope section.After the completion of tunnel construction,the ground motion causes a large response in the steep slope section,while the acceleration saturation phenomenon appears in the gentle slope section.The tunnel has reinforcement effect on surrounding rock,and deterioration effect on slope.The shear strain at the junction of stepped slope protection and near 2/3 of the slope foot is relatively large due to ground motion,and the response law is significant with the increase of ground motion intensity.With the increase of ground motion intensity,the effect of rock-soil structure is enhanced,and the stress of shallow buried tunnel vault and right arch waist is more unfavorable.The energy ratio of 0.1-6.25 Hz(low frequency wave)is consistent with the acceleration along the measuring point,which is the main factor causing soil response and failure.With the increase of elevation,the low-frequency wave energy proportion increases in steep slope section,and decreases in gentle slope section,while the change trend of high-frequency wave is opposite to that of low-frequency wave.This study has certain reference significance for seismic design of double arch tunnel and slope in soft surrounding rock in loess area.
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