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Abstract The control of soil deformation and the rectification of shield machine tilting are the major technical difficulties in double-O-tube(DOT) tunnel constructions. In this paper，the tilting characteristics of a DOT shield machine during construction were analyzed. Based on the theory of stochastic medium，the relationship between tilt angle and surface subsidence and horizontal deformation was derived by transformation of the coordinate system and integration over several partitioned areas. The relationship was then applied in the analysis of two case studies：anticlockwise and clockwise tilting. As demonstrated，the tilting of the DOT shield causes additional surface deformation and results in asymmetric surface deformation curves compared with symmetric profiles when there is no tilting. There are three focal points(V1，V2 and V3) on the surface subsidence curve and four focal points(H1，H2，H3 and H4) on the horizontal surface deformation curve，where surface deformation increments of soils occur in opposite directions on either side of any focal point. For anticlockwise tilting of the DOT shield，the additional vertical deformation of soils on the left side of V1 and between V2 and V3 is upward while that on the right side of V3 and between V1 and V2 is downward. The additional horizontal deformation of soils between H1 and H2 and between H3 and H4 is positive while that between H2 and H3，on the left side of H1 and on the right side of H4 is negative. The maximum surface settlement increases nonlinearly as the tilting angle increases and its position moves left. The maximum horizontal surface deformation to the right increases linearly while the maximum horizontal surface deformation to the left decreases slightly first and then increases，while the point with no horizontal deformation gradually moves left. For clockwise tilting，additional surface deformation of soils on both sides of any focal point is in the opposite direction to that of the anticlockwise case. The maximum horizontal surface deformation to the right decreases as the tilt angle increases and both the position of the maximum surface settlement and the point with no horizontal deformation gradually move right.
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2015, Vol. 34 
