Research On Design And Construction Of Reinforced Concrete And Steel Sheet Pile Combined Cofferdam

Mengxi Central Railway Dongting Lake Bridge is located in tidal flat of Xiangjiang River,from the river mouth about 2km,the bridge is a cable-stayed bridge with three towers six span steel box and steel truss, connection of the main bridge of the bridge is a five span continuous beam, continuous beam bridge ground elevation is about +27m, due to the continuous beam bridge bits (bridge pier 1#, n001 to N005# pier range of later need to dredge to the elevation +16m, in the design and construction plans six pier cap bottom elevation are located below ground 15 ? 17m, continuous beam based on ultra deep foundation pit, pile cap construction need of foundation pit support, and to go beyond the dredging requirements elevation part removed.The Dongting Lake Bridge Continuous Liangchao deep foundation pit, the latter part of dredging requirements, bridge site engineering geology engineering characteristics, introduced by the design and construction of the China Railway Bridge Bureau at the lower part of the reinforced concrete cofferdam (no need to dismantle) +upper steel sheet pile cofferdam of new combined cofferdam retaining structure, mainly for cofferdam design, cushion construction, monitoring and surveillance, sinks, and soil,steel sheet pile installation and other key technologies are described in detail.(1) The sand cushion replacement surface based combination of sleepers are arranged evenly and suction pad, to solve the combined cofferdam edge at the foot of foundation bearing force calculation and processing.(2) Through reasonable repeatly, simultaneous monitoring and control, with the focus on the control concrete cofferdam sinking speed and vertical degree, plane position deviation to solve the in soft silt strata of concrete cofferdam sinking in the vertical velocity and the degree of effective control.(3) Cap by drainage soil, non cap range shall not borrow and as weight, compared with the traditional cofferdam using undrained sinking need less water, sinking faster,and reduce the unreasonable soil workload, with increase of sinking depth, non cap regional soil retain more conducive to control the verticality of the combined cofferdam,closed non cap region can also as a regional cap concrete anhydrous sealing pressure.(4) The first installation in support, after the installation of the steel sheet pile,changed the traditional to install the steel sheet pile, after the installation of the beam, in support of the process method, both to improve the installation quality of steel sheet pile,and installation of steel sheet pile when operating platform cofferdam, safe and practical,more efficient, more to protect the quality of the.