Effect of Rainfall Infiltration on Stability of Surrounding Rock in Shallow Buried Small Clear Distance Section of Fangjun Tunnel
In order to control the influence of rainfall infiltration on the stability of surrounding rock of shallow buried small clear distance tunnel,relying on the Fangjun tunnel of the Yidong expressway,based on the fluid-solid coupling theory and the water-soil characteristic curve,the MIDAS GTS NX finite element software was used to establish a numerical model of a shallow buried small clear distance tunnel to analyze the soil pore water pressure,surrounding rock deformation characteristics and safety factors of side slopes were analyzed during construction in the rainy season.The results show that with rainfall infiltration continues,the matrix suction of the surrounding rock and slope soil gradually decreases,the shear strength of the soil also decreases,and the stability becomes worse.After 7 d of accumulated rainfall,the increase in pore water pressure gradually slows down,and the surrounding rock deformation reaches the maximum.The vault settlement in working condition 1 has increased by 21.48%,and the safety factor of the side slope is less than 1,indicating an unstable condition.Reinforcement and drainage measures are taken to control the stability of the surrounding rock at the tunnel entrance section,the safety factor of the side slope has increased by 17.27%compared with before reinforcement.The site has achieved good results,ensuring the safety of the tunnel's later construction.
shallow buried small clear distance tunnelrainfall infiltrationfluid-solid couplingmatrix suctionsurrounding rock deformation