Due to the short distance between the mined exit/entrance tunnel and the existing buildings, isolation piles are installed during the tunnel construction so as to ensure the safety of the existing buildings. By means of numerical simulations, analysis and calculations, the article makes a comparison of the settlement value after construction and that during each construction stage under two different working conditions, i.e., condition with isolation piles being installed between the tunnel and the existing buildings and condition with isolation piles being not installed, and draws a conclusion that installing isolation piles is a feasible solution.