前言确定桥下冲刷深度,是桥梁孔径计算的关键问题之一。苏联自1972年颁布新的《铁路、公路桥渡勘测设计规程》以来,在桥孔冲刷计算理论与生产实践方面又前进了一步,提出了不少新的概念和研究成果。桥下一般冲刷计算的极限理论(上极限、假定极限和下极限),就是不久以前提出来的。现 Foreword Determine the depth of scour under the bridge, bridge aperture calculation is one of the key issues. Since the Soviet Union promulgated a new code for survey and design of railway and highway bridges in 1972, the Soviet Union has taken another step forward in the calculation and design of bridge hole erosion and put forward many new concepts and research results. The limit theory of general erosion calculation under the bridge (upper limit, assumed limit and lower limit) was proposed not long ago. Now