Research on the Stress Mechanism of the Ultra-deep Open Caisson System during Subsidence Process

摘要

Considering limitation of the current design method of open caisson when it is applied to an ultra-deep one, the nonlinear three-dimensional finite element method is employed for the first time to analyze time-varying stress mechanism of the structure system during subsidence process after subsidence checking computations have been done. Spatial stresses of the open caisson-stratum system are calculated under 28 operating modes which are divided according to the construction procedure during subsidence process and integral structural analyses of the open caisson are carried out at the final designed elevation. The results of these previous researches indicate that, for ultra-deep open caisson, the stress ranges of the local domains of sidewalls can be underestimated by the present numeration method of structural strength; the secondary stresses of the upper linkage sections which have a tendency of descending will keep stationary eventually; the emphasis of checking computations should be the longitudinal bend of side and partition walls; the vertical loads are the major factors influencing the stress and deformation behaviors; the current checking calculation methods and constructional measures of cutting curb need to be adjusted. All the conclusions attempt to make reference to subsidence design and construction of other similar projects.