Design method and assembly method of side wall of steel hanging box cofferdam suitable for water level sudden change environment and/or multi-work-point turnover

The invention discloses a design method and an assembly method of a steel hanging box cofferdam side wall suitable for a water level sudden change environment and/or multi-work-point turnover, and the design method comprises the steps that the cofferdam side wall is designed in a layered mode in the vertical direction of a cofferdam, and the cofferdam side wall comprises a high-strength side wall layer and a low-strength side wall layer; the vertical ribs and/or the dowel bars and/or the annular plates are used for manufacturing the high-strength side wall layer, and the material specification of the vertical ribs and/or the dowel bars and/or the annular plates is correspondingly larger than that of the vertical ribs and/or the dowel bars and/or the annular plates used for manufacturing the low-strength side wall layer; the assembling method comprises the steps that the height of the large-strength side wall layer is h1, the height of the small-strength side wall layer is h2, and the water level depth during