5.2.1 The upstream/downstream river-closure cofferdam should bearranged in the area close to the dam axis, with straight river course,small work quantities, good topographical and geological conditionsand convenient area for construction.5.2.2 The distanc...[继续阅读]

    5.3.1 For the staged diversion, the layout of stage-Ⅰcofferdamshall be determined by analyzing the arrangement of main structures,topographical and geological conditions of longitudinal cofferdam,hydraulic conditions and construction site. Meanwhile, the ...[继续阅读]

    5.4.1 The layout of overflow cofferdam shall meet therequirements in 5.2.5.4.2 The overflow cofferdam axis should be perpendicular to theriver flow direction, so that the flow can be guided into main riverbed,and erosion hazard on downstream riverbed and ...[继续阅读]

    5.5.1 The cofferdam of powerhouse on river-bank should bearranged along the river direction according to the topographicalconditions, the converging effect of cofferdam to riverbed shall beconsidered, and the requirement of erosion control on riverbed and...[继续阅读]

    6.1.1 The structure design of cofferdam shall conform to therelated design codes of hydraulic structures, but only normal floodconditions shall be considered in load combinations. For importanttemporary retaining cofferdam for power generation, seismicche...[继续阅读]

    6.2.1 For longitudinal cofferdam, hydraulic calculation of diversionin each stage shall be conducted in sections so as to determine thedesign flood level, flow velocity and flow regime of flood in eachstage. If necessary, the hydraulic model test of const...[继续阅读]

    6.3.1 The calculation of stability against sliding for theearth-rockfill cofferdam slope and overburden foundation should beconducted by rigid limit equilibrium method with single safety factorbased on DL/T 5395 Design Specification for Rolled Earth-rockf...[继续阅读]

    6.4.1 The vertical normal stresses of foundation surface andcofferdam body for concrete gravity cofferdam shall be calculatedaccording to DL/T 5108. When the maximum and minimum verticalnormal stresses are calculated with material mechanics formula, theal...[继续阅读]

    6.5.1 The crest elevation and crest freeboard of non-overflowcofferdam shall conform to the following requirements.(1) The cofferdam crest elevation shall not be lower than the sum ofstatic level of design flood, wave height and crest safety freeboard.The...[继续阅读]

    6.6.1 The cofferdam body structure of earth-rockfill cofferdamshall conform to the following provisions.(1) The compaction index of cofferdam body above water surface forthe earth-rockfill cofferdam of Grade 3 may be taken based onDL/T 5395. The compactio...[继续阅读]