Experimental Study On The Effect Model Of Dynamic Compaction Reinforcement Under Low Water Content

The dynamic compaction method is to improve the bearing capacity of foundation soil,reduce the compressibility and eliminate the wettability,and use the lifting equipment to lift the weight to a certain height,and then make its free fall to tamper with the method of foundation soil.Due to its construction technology,simple operation,low construction cost,strengthening effect is remarkable,and many other advantages,widely used since its advent,still does not have a complete theory to support dynamic compaction construction design.For dynamic compaction method,the goal is based on the least amount of tamping energy to achieve the desired compaction effect.So the effect of dynamic compaction reinforcement effect research will also be necessary to various construction parameters,and one of the important parameters is the soil water.Based on the conditions of many water shortage areas in our country,in the process of the construction of dynamic compaction method is difficult to achieve at optimal water content condition.Study of dynamic compaction reinforcement effect experiment under low water content become inevitable.This paper through the indoor compaction test have formed by model test samples of the optimum water content,and then according to the principle of similarity,formulated the dynamic compaction of large scale model test scheme,using self-made instrument,the dynamic compaction of indoor model test of soil samples under the condition of 7% ~ 13%moisture content of dynamic simulation test,and the amount of the settlement of the foundation soil in the process of dynamic compaction,dynamic stress,peak acceleration rammer reflect the test parameters of dynamic compaction reinforcement effect is studied.The main results:1)Analyzed the 4000kN·m and 8000kN·m level,different water content and the changing rule of the dynamic compaction between total settlement.Results show that with the increase of water content,total settlement growth trends,when moisture content is more than11%,the total settlement increased tends to slow.The acceleration time history curve of rammer was analyzed,and the peak value of acceleration were studied.2)Analysis of the variation rule between different energy levels and the total settlement of the dynamic compaction of different energy levels under the 13% and 7% water content.The results show that the total settlement amount increases with the increase of energy level.Under the same energy level,soil with high water content,the total settlement volume is large.Under low water content,the reinforcement effect will improve with the increase of energy level,but the utilization rate of its energy will show the trend of decreasing first and then decreasing.The peak acceleration of rammer and the dynamic stress of soil are analyzed.3)The influence of eta on the compaction under the condition of low water content is studied,and the results show that the larger the eta value is in the same level condition,the more obvious the reinforcement effect is.4)For dynamic compaction lamping efficiency are analyzed in theory,and the change of the soil modulus of deformation before and after dynamic compaction is used to estimate each blow soil under tamping times,the vertical settlement,make use of the dynamic stress on the vertical direction to do work to evaluation of dynamic compaction to do useful work,get low moisture content under the condition of dynamic compaction energy conversion efficiency can reach 48%.5)Based on the effective reinforcement depth formula proposed by Fei Xiangze et al.,Combined with the experimental data,the applicability of the formula to the energy level above 10000 kN·m above 7% is analyzed.