三三○工程二期纵向围堰采用在混凝土基座上插钢板桩的格型围堰。这种围堰是用钢板桩以锁口相互扣接而围成一定形状的封闭空间(单个空间称为格体),内填砂砾石料,利用钢板桩防渗和保持结构形状,依靠砂砾石重量保持稳定。三三○工程 Three three ○ ○ Project Ⅱ longitudinal cofferdam used in the concrete base plate inserted steel sheet cofferdam. This type of cofferdam is a closed space (a single space is called a cell body) surrounded by a steel plate pile with a locking mouth and interlocking with each other. The cofferdam is filled with gravel material, the steel sheet pile is used for seepage prevention and structural shape retention, the gravel weight keep it steady. Three hundred and thirty project