Abstract: Given the structural features and engineering geological conditions of north anchorage large cylindrical caisson of Wuhan Parrot Cay Yangtze River bridges, combining with in-situ monitored data of some key points, three dimensional calculation modes of FEM are established with software ADINA to analyze stress and deformation of caisson structures and its adjacent diaphragm wall. The stress distribution and deformation of the structures are studied during the caisson sinking and its bottom sealing. The effects of caisson sinking on adjacent high-rise buildings and bank structures are also analyzed comparatively. The research results show that: the principal stress of diaphragm wall increases with the increasing of sinking depth, and its deformation appears mainly in its top and bottom after the caisson bottom sealing, the tension stress would be higher at its structure cutting edge, the middle of cross wall, the joints of cross wall and inner face of caisson well. The corresponding settlement of adjacent soil around the caisson increases with the increasing of sinking length as well. Settlements of monitored points from calculation agree well with measured data after bottom sealing, and the former is generally less than the latter. The differences between them are from -1.22 mm to -0.88 mm at the key points of adjacent high-rise buildings, and those at the key points near the Yangtze River bank are from -1.27 mm to 0.64 mm. The calculation model will provide a guide for settlement control during the caisson sinking.

Key words: anchorage caisson, diaphragm wall, finite element, stress, settlement, monitoring