Analysis of Surface Subsidence Rule of the Shallow Subway Tunnel Construction

In order to study the Dalian Metro section 202(Cujin Road station-Chunguang Street station, which is shallowly buried and covered with plain fill)’s ground surface settlement, the monitoring measuring station was built during the construction. After 3 months’ measuring by precision level,the data shows that the maximum point is in the center line of the tunnel of the upper part. The settlement is about 25.66-31.82mm. This paper put forward the concept of the distance span ratio β, β effective value range was - 4 <β< 4,Surface subsidence is closely related with β, Severe surface subsidence stage is -2 <β< 2, Occupy whole deformation is 67.5-77.6%,settlement rate about 0.84-0.93mm/d, so should strengthen the monitoring frequency, Suggest increases site tour. Field test results and the ground surface settlement calculation model winkle are identical with each other; the monitoring results have important guiding significance and reference for Dalian subway and the similar shallow depth excavation tunnel construction.