Research on Outer-Side Bottom Sealing Technology of Double-Wall Steel Cofferdams for Deep Water High-Pier Bearing Platforms
Double-wall steel cofferdams are usually used for high pier bearing platforms located in deep water with predominantly embedded in riverbed bedrock.In traditional construction methods,it is common to use inner-side bottom sealing for cofferdams,which implies a large amount of riverbed excavation,along with a substantial usage of bottom-sealing concrete and an extended construction period.Based on these reasons and combined with the practical problems of the Liujiang Dual-line Extra-large Bridge project,a technology for outer-side bottom sealing of double-wall steel cofferdams for deep water high-pier bearing platforms has been proposed(patent granted).The method utilizes a steel structure working platform with a pile drilling machine to excavate the riverbed down to the foundation level of the pier.Afterwards,on the outer side of the double-wall steel cofferdam,double-hole grouting pipes are arranged at certain spacing,penetrating deep into the bottom of the steel cofferdam.At the same time,angle steel is used to connect iron plates with a height of 1 meter on the outer side of the cofferdam bottom,forming a bottom-sealing groove.Finally,pouring of the outer sealing concrete and grouting to fill the leaks.Based on practical experience,it is shown that new method has the advantage of achieving a closely adhered and effective bottom-sealing.It is also pointed out that the new method,compared to traditional approaches,reduces the amount of riverbed excavation and concrete usage,and shortens the construction period.Therefore,it can be used as a reference for similar projects.
double-wall steel cofferdamouter-side bottom sealingdouble hole groutingdeep water high-pierbearing platform
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