Abstract: In order to get the direct calculation formula for impact pressure on the base of X-shaped flaring gate pier, we analyzed and obtained a few influence factors on impact pressure. Through fitting a lot of data of model test with dimensional analysis, an empirical formula well reflecting the law of impact pressure was suggested. At the same time, several projects such as Gunnong, Ludila, Suofengying and Shatuo were studied .Error analysis shows that maximum relative error of impact pressure for the four projects is not more than 16.3%, which can reflect the hydrodynamic pressure of complicated flow in the stilling basin well. Examples show that, in Ahai project’s X-typed flaring gate pier, the error between calculation value and test value of maximum impact pressure is less than -15.8%.

Key words: X-typed flaring gate pier, stilling basin , base, impact pressure, dimensional analysis, empirical formula