Study Of The Construction Scheme For The Large Open Caisson In The Water Intake Of Water Treatment Plant:

The technology of open caisson develops rapidly and is widely applied in the sinking-mode water supply and drainage facilities.In this study,the control points of concrete underwater sealing and the deviation recitification of sinking dynamics of open caisson are studied according to the actual engineering.Results are shown as follows:1.In the construction of open caisson where underground water level is high,with poor geological conditions or close to the levees,open caisson construction of undrained sinking scheme should be adopted.Before the production of open caisson,the corresponding thickness of sand cushion should be laid at the bottom to ensure the structure safety and the stability of the sinking of open caisson;2.For large open caisson construction,the continuity of concrete pouring should be maintained.Before being covered,the lower concrete should be cut hair and removed the surface laitance to ensure the bond strength of the lower concrete;3.Open caisson sinking construction should be done according to the principle of "middle and edge,layering and symmetry break,high and low,timely rectification".During the final sedimentation,less than 2.0m of the design height,the sinking rate should reduce and observe the elevation every 20 minutes.The bottom digging depth should be reduced and the soil height in each square should be equal to ensure slow sinking of the open caisson.4.The bottom sealing and concrete construction is conducted according to the principle of"symmetrical sequence,borrow and sealing,pouring with double catheter in a same compartment".Based on the principle of open caisson symmetry stress,the bottom sealing should be done according to the sequence of "low and high,around and middle" to ensure the quality of the bottom sealing.Through the studying of the control points of concrete underwater sealing and the deviation recitification of sinking dynamics of open caisson,the obtained priciples are significant to guide the future design and construction of open caisson.