Abstract More and more viaduct and metro tunnels are constructed concurrently or in close succession, and tradi? tional passive support measures have the disadvantages of poor control, severe disturbance and poor selectivity restricted by confined spaces. Using a shield tunnel of Jinan metro line R1 that approaches to the proposed viaduct pile as an example, the active pre-support techniques of a frame structure, three-axis mixing pile structure and diaphragm wall are put forward, and the characteristics of the surface settlement, deformation law of the viaduct pile and principal stress distribution of the segment under different support conditions are analyzed. The study results show that: 1) the tunnel settlements, pile foundation deformation and segment principal stress present various tendencies under different support conditions, and the viaduct pile deformation and segment compressive stress reach their maximums without advance support; 2) with the continuous decrease of the frame structure spacing, the outeredge deformation of the pile cap increases and its center deformation decreases gradually; 3) the separation and control effect of the three-axis mixing pile is poor because of its low stiffness; 4) the reinforcement and control effect of the multi-frame structure, mixing-pile embedded precast pile and diaphgram wall increase gradually; and 5) in ac? tual construction, the multi-frame structure should be given priority due to its uniform control effect on the various control indexes, economy and ease of construction, while the mixing- pile embedded precast pile and diaphragm wall support have advantages in unfavorable geological conditions.
Abstract：
More and more viaduct and metro tunnels are constructed concurrently or in close succession, and tradi? tional passive support measures have the disadvantages of poor control, severe disturbance and poor selectivity restricted by confined spaces. Using a shield tunnel of Jinan metro line R1 that approaches to the proposed viaduct pile as an example, the active pre-support techniques of a frame structure, three-axis mixing pile structure and diaphragm wall are put forward, and the characteristics of the surface settlement, deformation law of the viaduct pile and principal stress distribution of the segment under different support conditions are analyzed. The study results show that: 1) the tunnel settlements, pile foundation deformation and segment principal stress present various tendencies under different support conditions, and the viaduct pile deformation and segment compressive stress reach their maximums without advance support; 2) with the continuous decrease of the frame structure spacing, the outeredge deformation of the pile cap increases and its center deformation decreases gradually; 3) the separation and control effect of the three-axis mixing pile is poor because of its low stiffness; 4) the reinforcement and control effect of the multi-frame structure, mixing-pile embedded precast pile and diaphgram wall increase gradually; and 5) in ac? tual construction, the multi-frame structure should be given priority due to its uniform control effect on the various control indexes, economy and ease of construction, while the mixing- pile embedded precast pile and diaphragm wall support have advantages in unfavorable geological conditions.
2017, Vol. 54 