The formation of the scoured pits is related with such factors as the unstable flow velocity and the unstable flow state caused by the circumfluence in the cross direction , the upstream circumfluence and the circle flow around the embankment 冲刷坑的形成与横向环流、上游回流和绕流丁坝造成流速及流态不均匀等因素有关；根石走失与根石在水中的稳定性和河床性质及坝脚附近冲坑有关。
Through theoretical computation and experimental observation , it is put forward that the maximal depth of the scoured pits of the embankment is from ten to thirteen meters , and for several pits whose top are rinsed by main flow continuously , their scoured depth have reached twenty meters 经过理论计算和试验观测研究，提出了仁存渡以下沙质河床，丁坝最大冲刷坑水深为10 ? 13米，个别受主流持续顶?的丁坝，最大冲刷坑水深可达20米。
The main contents and conclusions are as follows : 1 . the dynamic pressure on the original riverbed and the scour hole are measured . the results show that the characteristics of dynamic pressure in the scour hole are the same as that on the original riverbed 表明在基岩冲刷过程中以及冲坑稳定后，射流冲击区的脉动压强与冲坑形成前一样，都是以低频大振幅为主，说明在冲刷坑形成后，射流冲击区水流与无冲坑时一样，都是大尺度涡不断破碎和小尺度涡不断生成的过程。
Abstract : the scour process at the rear apron of shimen dam is studied through review of operation practice and inverse operation experiments . the cause of scour is explained , the scour pot was not stable after the occurence of extreme flood with the return period of 300 years , and the flood may deepen the scour pot even more severe 文摘:通过长期实践和反演试验，研究了石门拱坝投运26年来坝后冲刷坑动态发展的全过程，解释了其形成的主要原因，并指出重现期300年的特大洪水发生后，石门冲坑并未稳定，小于它的洪水仍旧造成了更深更危险的冲刷。
With same opening depth applied at dam no . 3 , deeper scouring hole was found at the downstream channel of dam no . 4 when the dam - conversion was conducted simultaneously . besides , the depth of downstream scouring hole of dam no . 4 increased with increasing opening depth at dam no . 3 . 3 . changes in the channel cross sections between dam no . 3 and no . 4 三号坝坝体拆坝的方式会对四号坝下游冲刷坑的深度会产生影响，由坝体相同断面的拆除，结果发现一次拆除会比分次拆除时造成冲刷坑的深度较深，而冲刷坑的深度会随著下游坝体拆除的深度增加而变大。
In order to explore harness scheme , layout , measurements and parameters concerned of the project , which are appropriate for the characteristic and the evolvement law of the watercourse of ningxia section of the yellow river , the study on the experiment of the scoured pit of the dam buttress and runoff of the root rock of ningxia section of the yellow river is of important theoretical meaning and practicable value 河道床质也不相同，仁存渡以上河段为沙卵石，以下河段为沙质。为了探索适宜黄河宁夏段河道特性和演变规律的整治方案、工程布局、工程措施及有关参数，开展黄河宁夏段河道坝垛冲刷坑和根石走失试验研究，具有十分重要的理论意义和实用价值。
The scour process at the rear apron of shimen dam is studied through review of operation practice and inverse operation experiments . the cause of scour is explained , the scour pot was not stable after the occurence of extreme flood with the return period of 300 years , and the flood may deepen the scour pot even more severe 通过长期实践和反演试验，研究了石门拱坝投运26年来坝后冲刷坑动态发展的全过程，解释了其形成的主要原因，并指出重现期300年的特大洪水发生后，石门冲坑并未稳定，小于它的洪水仍旧造成了更深更危险的冲刷。
The existing results about scour hole was summarized . experiments was made about the influence of aeration on scour , the dynamic pressure on the original riverbed and the scouring hole bottom , and the influence of aeration on the dynamic pressure and the velocity of submerged jet . scour was simulated by numerical model 在总结前人研究成果的基础上，试验研究了掺气对基岩冲刷破坏的影响；基岩冲刷过程中冲坑底部脉动压强随冲坑深度的增加而变化的特性；掺气对冲坑未形成前河床底部及基岩冲刷坑底部脉动压强的影响；掺气对射流轴线流速变化的影响等。
Based on the local scouring test of the dike ' s head under the action of clear tidal currents , of both tidal currents and waves , and of both muddy tidal currents and waves , variations of the scoured pit ' s depth at each dike ' s head with time , and the scoured pit ' s depths with three experimental conditions are compared 进行了清水潮流和潮流波浪、浑水潮流波浪作用下的4条丁坝坝头冲刷试验，给出了各丁坝坝头冲刷坑深度随时间的变化，对比了3种试验条件下丁坝坝头冲刷坑的深度。
