Seismic resilience analysis of high-speed railway tunnels across fault zones using ensemble learning approach

Severe damage to the Daliang high-speed railway tunnel during earthquakes primarily results from the dynamic interplay between fault dislocation and intense seismic forces near fault lines, accompanied by their complex feedback mechanisms. This study introduces a novel hybrid finite element model to explore the impact of fault dislocation-induced earthquakes on tunnel lining integrity. The influence of seismic characteristics on factors such as peak ground acceleration, tunnel structure form, and the shear modulus of surrounding rock is analyzed. Extensive numerical simulations investigate the coupling effects of faults and various seismic motions on tunnel structures. Additionally, a rapid resilience assessment model for tunnels crossing strike-slip faults is developed using the Adaboost algorithm. This model evaluates the seismic fragility and resilience of such tunnels, offering insights into the anti-seismic behaviors of three distinct tunnel lining configurations under the combined stresses of fault dislocation and significant seismic activity. Furthermore, the fault damage characteristics of the crossing-fault high-speed railway tunnel are assessed, based on real earthquake damage classification and current seismic codes. Findings demonstrate that the evaluation model is both highly accurate and efficient, serving as an effective alternative to traditional nonlinear time-history analysis of tunnel structures. Research establishes that critical factors influencing seismic fragility and resilience include the structural design of the tunnel, shear modulus of the surrounding rock, peak ground acceleration, and tunnel height. Simulations reveal that tensile and compressive damage are significantly reduced in circular tunnels with a shock-absorbing joint compared to original tunnel prototypes. Overall, damage assessments from actual faults in crossing-fault high-speed railway tunnels correlate well with numerical predictions, providing essential references for structural recovery and safety evaluations post-earthquake.