Abstract:

The sandbag cofferdam of Honggu Tunnel in Ganjiang River was destroyed by winter season. It has to be reconstructed so as to provide waterless working conditions for further construction. New construction scheme of “earthrock cofferdam + plastic concrete bored secant pile and high pressure jet grouting pile seepage prevention system” is adopted. The scheme includes, rock filling along axial line of cofferdam by grab dredger, rock pushing towards cofferdam by dump truck, using plastic concrete bored secant pile constructed by reverse circulation drill and high pressure jet grouting pile seepage prevention system. The construction practice shows that the reconstructed earthrock cofferdam has advantages of rapid construction, low cost, small operating area, stable and impermeable； so that it can be applied to new and reconstructed temporary hydraulic engineering works.

Key words: immersed tunnel, sandbag cofferdam, earthrock cofferdam, reconstructed cofferdam, plastic concrete bored secant pile