4021大桥4号墩基础采用直径11.5米(底节尺寸)的圆沉井,沉井共3节,总高25米,穿过的复盖层主要是卵石,坐落在基岩上。沉井在施工过程中发生了倾斜。主要原因是,沉井南侧位于水边,北侧处在河滩上,筑岛时南侧填有卵石,北侧系原沙层,两侧刃脚下土层承载能力不同。此外,灌注第一节混凝土时,固定在北侧下料,由于混凝土侧压力作用,使北侧刃脚处模板变形,产生“鼓肚子”现象,增加了北侧刃脚下的正面阻力,使沉井一开始下沉就往南位移。再之,开挖出土和水泵排水 Pier No. 4021 Bridge Pier No. 4 uses a diameter of 11.5 meters (bottom size) Round sunk well, a total of 3 sunk well, a total height of 25 meters, through the cover is mainly pebbles, is located in the bedrock. Caisson was tilted during the construction. The main reason is that the south side of the caisson is located on the water’s edge, the north side is on the river bank, the south side of the island is filled with pebbles, the north side is the original sand layer, and the bearing capacity of the soil under the two edges is different. In addition, the first section of concrete perfusion, fixed in the north of the material, due to the role of the concrete side of the pressure, the north edge of the template at the deformation of the foot, resulting in “drum belly” phenomenon, increasing the north side of the front edge of the blade resistance, The well sank to the south as soon as it began to sink. Again, excavated and pump drainage