Numerical Simulation Study On Dynamic Consolidation Of Foundation

In recent years,dynamic compaction method is widely used in foundation treatment.Due to the complexity of dynamic compaction foundation treatment,the dynamic compaction theory lags far behind the engineering practice,and the effect of dynamic compaction foundation treatment varies greatly under different conditions.This thesis takes a dynamic compaction project in Fujian Province as the research object,establishes a finite element model through ABAQUS for numerical simulation,verifies the reliability of ABAQUS three-dimensional dynamic compaction model,and studies the impact of tamping times,tamping methods,tamping energy and other factors on the foundation reinforcement effect.The main research conclusions are as follows:(1)Under the condition of single tamping,the tamping settlement first increases and then decreases.The growth rate is fast in 0-0.1s,reaching the peak value in 0.24 s,and the elastic deformation of soil body recovers after 0.24 s.The tamping settlement will decrease to a certain extent.The effective reinforcement depth of single tamping is 6.5-6.6m.With the increase of tamping times,the growth rate of tamping settlement and effective reinforcement depth decreases,and the optimal tamping times are 7.The maximum principal stress increases with the increase of tamping times and decreases with the increase of depth.8.2-8.3m deep,plastic strain attenuates to 0,indicating that the impact depth of dynamic compaction after the seventh tamping is 8.2-8.3m.(2)When the momentum increases from 3652 kg · m/s to 7302 kg · m/s,the tamping settlement increases by 0.74 m.Obviously,the tamping settlement increases with the increase of momentum,which is consistent with the tamping method of "heavy hammer falling" in actual projects.(3)When the single tamping energy increases from 2000 k N · m to 3000 k N · m,the tamping settlement increases by 0.13m;When the single tamping energy of 7000 k N · m increases to 8000 k N · m,the tamping settlement increases by 0.06 m.The single tamping energy increases from 2000 k N · m to 8000 k N · m,and the time taken for the tamping settlement to reach the peak value increases by 0.14 s.Obviously,with the increase of tamping energy,the single tamping settlement also increases,but the increase is slowing down,and the time when the tamping settlement reaches the peak value is increasing.(4)Taking the tamping settlement as the consideration index,the orthogonal test was established by comprehensively selecting the influencing factors and levels,and the influence degree of each factor on the consideration index was obtained as follows:hammer weight>hammer diameter>drop distance.After optimization,the single tamping settlement of the dynamic compaction combination has increased by 0.3m,with a growth rate of 47.4%.The dynamic compaction effect is more ideal.