In the construction of a tunnel in large loose deposit surrounding rock of an expressway,the vault collapse,advance support smash and secondary lining cracking lead to the multiple changes in excavation scheme. The mechanical parameters of loose deposits were obtained with the large-scale indoor isotropically consolidated drained( ICD) shear tests,and such construction processes as the up and down bench tunneling method,three bench tunneling method and single side heading method were simulated with the thre...