长江含砂量虽不高,但由于水量大,年输砂总量仍相当可观。每年通过葛洲坝坝址之输砂量约有5亿多吨,在枢纽布置上,对于排砂问题应予重视,提出了“孔孔皆泄水,无孔不排砂”的设计原则。除靠泄洪排砂外,为了防止粗颗粒泥沙过机,保证电站正常运行,采用了设有排砂底孔的混合式电站塑式。其主要目的是,除排砂外,亦可利用出口的高速水流,压低尾水位,印所谓“射流增差”,以期提高机组的出力。排砂底孔的进口位于机纽进水口的下部,绕道蜗壳侧旁向上翘起,出口位于电站尾水管的卜部. Although the amount of sand in the Yangtze River is not high, the total amount of annual sand transportation is still considerable due to the large amount of water. The annual sediment discharge through Gezhouba Dam site is about 500 million tons. At the layout of the hub, attention should be paid to the problem of sand discharge. The design principle of “discharging holes without holes and without holes with no sand” should be put forward. In addition to rely on flood discharge sand, in order to prevent the coarse particles of sediment over the machine to ensure the normal operation of power plants, with sand bottom hole hybrid power plant plastic. Its main purpose is to remove the sand, but also can use the export of high-speed water flow, down the tail water level, the so-called “jet increase” in order to improve the unit’s output. The bottom of the sand discharge hole is located in the lower part of the machine inlet, next to the bypass volute side up tilt, the outlet is located in the power station Bu Bu Department.