Analysis of factors affecting tensile stress of large caisson during sinking
To study the influence factors of tensile stress during the sinking process of large caissons,based on the north anchorage caisson of Wufengshan Yangtze River Bridge,the numerical model was built by ABAQUS finite element software and verified by the field measured concrete stress data.The influence factors of concrete stress for caisson foundation,such as initial subsidence height,the excavation method,the plane size of the caisson were analyzed by the control variable method,and the measures for preventing and controlling of pulling cracks of bridge caisson foundation were put forward accordingly.The results show that during the initial sinking process of large caissons,the tensile stress in the width direction of the concrete is often greater than its length direction,and the larger the aspect ratio of the caisson,the greater the tensile stress ratio in the width direction to the length direction.Therefore,the tensile stress in the width direction should be the focus of engineering monitoring.The tensile stress of the caisson partition wall can be approximately analyzed by the theory of beams,but the interaction of the partition wall at the intersection should be considered.The initial subsidence height,excavation method and external load of caisson have a great influence on the tensile stress of concrete for caisson foundations,the maximum tensile stress of the caisson increases linearly with the increase of external load,and the eight zone excavation method reduces the maximum tensile stress of the concrete by nearly 90％compared to the large pot bottom excavation.Increasing the initial sinking height can reduce the maximum tensile stress of the concrete by nearly 50％.Increasing the initial subsidence height and adjusting the excavation method can be achieved only by changing the construction process,which are more economical and reasonable methods to control the tensile stress.By contrast,the influence of concrete strength,partition wall width,side wall width,etc.on tensile stress is relative small,so there is no need to focus on them during the sinking of large caisson.3 tabs,15 figs,28 refs.
bridge engineeringlarge open caissonFEManalysis of internal forceinfluence fac-torprevention and control measuresinking
NETL
NSTL
万方数据
维普
