水下重锤夯击能及夯击效果试验研究

Water hammer tamping energy and the experimental study on compaction effect

重锤夯实是水下抛石基床密实工艺中的重要方法。根据流体动力学,本文建立夯锤在水中运动的计算模型,然后通过室内缩比尺试验,得到了夯锤水下绕流阻力系数经验取值;最后探讨了不同夯锤几何、不同落距对夯实效果的影响。结果表明:圆台型夯锤与圆柱形夯锤相比,由于有倒角,在水中的绕流阻力系数可以小至1.0;同一夯击能作用下不同锤型对抛石基床的夯实效果相差在5%之内;同一夯锤不同落距作用下,落距越大,抛石基床沉降量越大,夯击应力越大,但抛石基床沉降率存在一个极限值。

Heavy tamping method is a kind of important method of rubble bed tamping in the construction,the heavy hammer tamping energy is an important indicator of impact compaction hammer effect,the hammer tamping energy can be influenced by hammer type,flow resistence,drop distance and other effects. Therefore,on the basis of fluid dynamics. First of all,establish the calculation model of the hammer in water movement,analyse the hammer flow resistance in the process of hammer in water movement,and then through the indoor shrinkage scale test,analyse the water movement law of the cylindrical and cone hammer,obtain the experiential tamping hammer water flow coefficient value.Finally,analyse of the different geometric rammer,different distance to the effect of compaction effect. The results show that a cone type tamping hammer and cylindrical rammer compared. Because of the chamfer of a cone type hammmer,flow resistence coefficient is smaller in water and the value is about 1. 0. under the action of the same tamping energy,different types of hammer has difference in5% on the rubble mound foundation compaction effect. with a hammer in different falling distance,the greater the falling distance is,the greater the amount of settlement of riprap foundation bed is,the bigger the compaction stress is. but rubble mound foundation settlement has a limit value. The research results can provide reference for the selection of hammer shape under the process of compaction.