Characteristics of Soil Surface Settlement for Double-O-Tube Shield Tunnel

Double-o-tube(DOT) shield method is a new method to construct tunnel in the development of underground space.DOT shield tunnel has many advantages,such as less underground space occupancy,higher construction efficiency,less soil excavation,etc,but larger surface settlement and larger disturbance of soils exist in the construction of DOT shield tunnel.Based on the characteristics of the DOT shield tunnel construction,the soil surface settlement was studied using the method of the displacement overlapping.The relationship between the soil surface settlement and the tunnel depth,the tunnel diameter and the gap parameter was also derived.It is shown that the soil surface settlement curve of DOT shield tunnel is similar with that of circle tunnel;the soil surface settlement and the width of the settlement trough of DOT shield tunnel are larger than those of circle tunnel,and the soil surface settlement of DOT shield tunnel is related to the ratio of the depth to diameter of tunnel.