Construction process is of significance for geotechnical performance of underground facilities. The mechanical properties of underground crude oil storage caverns under different drainage conditions and subjected to different excavation processes is studied by using fluid-solid coupling theory. It is shown that drainage condition and excavation sequence are important for pore pressure distribution and stability of the caverns. Pore pressure around the caverns in the drained cases is lower than that in the undrained cases. In the drained cases

the pore pressure distribution and groundwater inflow flux are dependent on the excavation sequence. The extents of excavation induced loose zones in undrained condition are much higher than those in drained condition. The distributions of radial and tangential stresses are dependent on the excavation sequence. The horizontal convergences in drained cases are lower than those in undrained cases; while the crown settlements in drained cases are higher than those in undrained cases. In the same drainage condition

the deformation of caverns is dependent on the excavation sequence. The results could not only provide a reference for the construction of the underground crude oil storage caverns

but also enrich the scope of the principles for construction process mechanics.