The Ways To Tackle The Problems Under Different Conditions In Double-Wall Steel Cofferdam Construction Of Bridge Foundation

In recent years, with the continuous development of China's economy, more and more bridges surmounted major rivers have being constructed, and the technology of the foundation construction have being improved. The most common difficulties for the constructing of deep bridge foundation are waterproofing, earth standing, even anti-corrosion and land sliding etc. The purpose to construct a cofferdam is to prevent the water and soil outside the cofferdam to rush into it during cofferdam construction and foundation construction. The cofferdam shall be dismantled after the foundation, abutment and pier being constructed above the water level in order not to block the waterway and the stream. Double wall steel cofferdam is one of the widely used waterproofing cofferdam for the construction of deep bridge foundation.In this paper, associating with the deepwater foundation construction practices I participated in which include Zishui Bridge on Zhuliu multiple line and the Huaihe River Railway Bridge from K831 of Jingpu line to Bengbu station, I discuss the deepwater bridge construction difficulty—cofferdam construction under the condition of low capped pile foundation . It elaborates the double-wall steel cofferdam construction technology in detail and propose related problems which should be paid attention to in the construction course. There is a creative mentality in Construction technology, namely using the annular channel excavation on the deepwater river bed surface, which adopts a new construction technology aiming at the construction characteristics that there is no overburden layer on the river bed surface in the position of 42# pillar foundation. Meanwhile the high pressure jet grouting technique is used in the deepwater steel cofferdam construction, which is an exploration and development to the high pressure jet grouting technique.Moreover, in different geological, hydrological and environmental conditions of the construction site, elaborate in detail how to choose the reasonable processing and the assembling method of steel cofferdam, determine the sinkage and the back-cover scheme, and promptly solve problems encountered by the construction. At the same time, in order to minimize investment, reduce the cost of the project, the construction measures and programs of deepwater foundation must be based on local conditions. Associating with the summary analysis to the construction practices of double-wall steel cofferdam construction in the two different hydrological and geological conditions--the mountainous area rivers and the plain area rivers, propose the construction methods applied under different environments and conditions. To reduce the cost and ensure the smooth progress of the construction, my own views are proposed, and the in-depth discussion is also carried out.