通过现场监测的方法，对顶管工程圆形沉井在不同顶力作用下后背土体反力和位移变化进行分析研究，并结合有限元数值模拟方法，对现有不同的工作井后背土抗力分布形态进行对比验证．研究结果表明：圆形沉井工作井后背土抗力分布近似直线，但在沉井底板深度处因底板处刚度较大而产生突变，而后在刃脚处达到最大；顶力作用下沉井后背土体发生的位移较小，并表现为整体移动；验证了在沉井后背土体产生较小位移情况下视沉井前壁未达主动状态的合理性，进一步给出沉井后背土反力随距离的变化规律．

Analysis of soil counterforce and displacement of circular caisson pipe jacking project was made under the effect of different top edge using the site monitoring method as well as the comparative validation of distribution pattern of resistance of different open caisson using finite element numerical simulation methods. The results show that the distribution pattern of resistance of open caisson is approximated by a straight line which mutates in the depth of the caisson bottom due to the stiffness of the floor at large and reaches the maximum at the foot. The displacement of soil occurs less but as a whole under the jacking force. Simultaneously, the rationality of less than the active state was verified in the case that the soil of open caisson produces a smaller displacement under the caisson sinking back below the front wall of the active state which gives the variation of inking back soil reactions with the different distance.