Abstract: This case study aims to investigate the disaster evolution process of tunnellandslide system and tunnel stress response characteristics under rainfall condition and reveal the evolution mechanism of the rainfalllandslidetunnel system. This study is conducted on tunnel landslide of Yangjiawan tunnel of Fengxi highway in Chongqing, China. The laboratory model test used in this study reveals the following results. (1) Under rainfall infiltration, the slope disaster evolution process shows a slope top tensioningmiddle slope creeping slipslope foot traction damage trend. (2) As the soil is softened by groundwater, it creeps and deforms, resulting in the downward transmission of the excess sliding force along the direction of the slip zone. This results in the formation of a large compressive stress at the slope foot that acts on the mountain side of the tunnel. (3) The tunnel crown, arch waist, and foot of the mountain side are prone to large stress concentrations, resulting in vertical tension cracks in the tunnel crown. (4) The whole tunnel model is mainly subjected to pressure under rainfall, and when entrance section is closer to the tunnel, the tunnel is subjected to bias pressure. The difference in bending moment values between the mountain side and the river side is 5.1~5.5 times, with uneven forces on both sides that forms a typical bias tunnel.

Key words: tunnellandslide system, rainfall infiltration, disaster evolution mechanism, model test