以金沙江向家坝水电站围堰沉井基础为研究对象，对沉井下沉过程中的刃脚土压力、井壁侧摩阻力进行了全面监测。根据大量现场的实测资料，系统地分析了沉井下沉过程中的受力特征，得出了沉井下沉过程中，经过不同深度、不同地层时的刃脚土压力及井壁摩阻力的大小及侧阻力呈抛物线形分布规律，同时提出了下沉系数K值的计算方法。据实测，3次下沉的K值均小于1.15时，表示下沉到位困难。

In the sinking process of caissons of cofferdam of the Xiangjiaba Hydropower Station, the side friction and the end bearing pressure of caissons were monitored. According to the observed data, the resistance character pressure systematically was studied during the sinking, and the distribution of wall side friction and end bearing force during penetrating into different soil strata were obtained. And meanwhile, the formula of sinking coefficient KS was proposed, and from observed data, when the KS was less than 1.15 during threetime sinking, the caisson reached designed location to be difficult.