Abstract:The Hengmen West Extra-large Bridge in Zhongshan City of Guangdong Province spans the Jiya Waterway (Class III waterway) and Xiaolan Waterway (Class I waterway), in which the main pier is located on an island surrounded by water on three sides. The bridge site is within the scope of a Class II water resources protection zone. The main pier base slab is located near the Xiaolan Waterway on the large mileage side, about 5 meters away from the nearest point of the original dam. The distance between the edge of the deep foundation pit of base slab and the embankment is too close, and there is a risk that the steel sheet pile cofferdam of the foundation pit will be affected by river water. In addition, a too thin external earth wall can damage the stability of the foundation pit. In response to the safety requirements of deep foundation pit support, through systematic analysis of the deformation mechanism of steel sheet pile cofferdams, based on the practical site conditions, the targeted comprehensive reinforcement schemes such as replacement of steel pipe pile cofferdam, optimization of internal support structures, and anti-seepage reinforcement of river embankments are implemented. During the construction period, in coordination with the full-process dynamic monitoring technology, the engineering risks are effectively controlled, and ultimately the safety of the foundation pit construction is smoothly guaranteed.
