Tunnels　in　urban　underground　roads　are　usually　constructed　adjacent　to　the　existing　tunnels　and　the　construction　of　newly-built　tunnels　may　lead　to　the　damages　of　adjacent　existing　tunnels.　So　it　is　very　important　to　investigate　the　influences　of　newly-built　tunnelling　on　adjacent　existing　tunnels　before　newly-built　tunnel　construction.　In　this　study,　a　series　of　numerical　simulations　were　performed　using　a　finite　difference　program　(FLAC3D)　to　analyse　additional　stresses　and　displacements　of　the　existing　tunnel　structure　induced　by　a　newly-built　tunnel　based　on　the　ground　conditions　in　Beijing.　Taking　the　additional　stresses　and　additional　displacements　of　the　existing　tunnel　structure　as　influential　partition　indexes,　the　influential　area　caused　by　the　newly-built　tunnel　was　divided　into　3　zones:　strongly　influential　zone,　weakly　influential　zone　and　inappreciably　influential　zone.　And　then　the　characteristics　of　each　influential　zone　were　introduced.　This　fundamental　research　can　provide　the　basis　for　a　more　rational　design　and　construction　of　adjacent　tunnels　in　Beijing　urban　underground　roads.　©　2015　ejge.