Research On Energy Consumption Of Impact Load Reinforcing Red Sandstone Soil Foundation

Red sandstone distributes widely in China, which is commonly used for backfillingfoundation. Dynamic compaction is a common method for reforcing foundation, and it iswidely used as its significant reforcement effect, simple construction conditions and fastconstruction speed, etc. While the study of theory of the impact load represented by dynamiccompaction reforcing red sandstone backfilling foundation is lagged. This paper selects thered sandstone from Gannan as the research object, and studies the effect and energyconsumption of the full ramming and single point impact loads at different thickness redsandstone. The following is the conclusions:1. Under the effect of the full ramming impact load, for the soil columns of differentthickness with the same total impact energy, the average cumulative settlement increases withthe increasing of soil columns. When the total impact energy is1905.12N·m (the impactnumber is12), the cumulative settlement of the soil column is close to steady state.For the same thickness of soil column, it needs to consume different total impact energy toreinforce to the different degree, and it needs476.28N m energy to increase1mm of thepost-settlement.2. Under the effect of the full ramming impact load, when the total impact energy isdifferent, the average dry density of the soil column with different thickness increases withthe total impact energy increasing and the average increment shows gradually decreasingtrend, and the higher the soil column, the more unconspicuous the increment of the averagedry density of the soil column and the smaller the obsorbing and passing of energy. When thetotal impact energy is the same, the average dry density of the soil columns does not increasewith the increasing of the thickness of soil columns, and the average dry density of the soilcolumns of120mm is maximal, the energy absorption effect of which is best, the energyabsorbed is2381.4N·m-2857.68N·m, and the energy consumption per unit volume of soil is1751.03N·m-2129.45N·m/(m3), the overall reinforcement effect is obvious.3. In the process of reinforcing soil by the full ramming impact load, as the total impactenergy increases, the dry density after the change of water content is slightly larger thanbefore, the maximum increment rate reaches3%, and the average increment rate is2.6%, sothe increment is relatively not so obvious. In the procedure of reinforcing soil by impact load, if moisture content is optimal, the variation of moisture content can be ignored tocompute theaverage dry density of the soil.4. Under the effect of single point impact load, in the case of the soil column of120mmthickness, the relationships expression of the total impact energy denoted by x and the averagecumulative settlement denoted by y is y=-68.221+22.721ln(x); y＇=22.721/x. It needs greaterenergy consumption to get higher degree of reinforcement for soil of a fixed thickness, and aswith the reinforcement of soil, it needs consume more energy when the cumulative settlementvalue of the soil increase1mm averagely; with the increase of the total impact energy, thesides uplift amount of all the soil layers of different thickness shows the phenomenon ofincreasing first and then decreasing, but it always keeps in a certain range.Conclusions made in this paper is helpful for the theory and practice of impact loadreinforcing the red sandstone backfilling foundation of Gannan distinct et al, and has a certaineffect on the basic design of foundation reinforced by impact load.