一、一般冲刷Neil(1973年)建议可通过四个途径估定冲刷深度。第一,观测类似建筑物的冲刷深度,用来估定实际工程条件下可能出现的冲刷深度,这是一种常用的方法;第二,选用较可靠的公式来估算;第三,对与实际工程条件类似的现场进行观测,确定河槽不冲刷平均流速,用来决定桥长和冲刷深度;第四种途径可按下列步骤进行:计算桥下天然断面通过Q_(max)时的桥孔平均流速(?);根据表1或图1选定不冲刷极限流速U_C;比较(?)和U_C,若(?)大于U_C,表明桥下将出现 First, the general erosion Neil (1973) suggested that there are four ways to assess the scour depth. First, it is a common method to observe the scouring depth of a similar building to estimate the possible scouring depth under actual engineering conditions. Second, we choose a more reliable formula to estimate. Third, The same method can be used to determine the length of the bridge and the depth of scouring. The fourth approach can be as follows: Calculate the average velocity of the bridge opening when the natural section of the bridge passes Q_ (max) ?); According to Table 1 or Figure 1 selected non-scouring limit flow velocity U_C; Comparison (?) And U_C, if (?) Is greater than U_C, that under the bridge will appear