Research On Efficacy Of Rigid Drainage Pipe Pile Improvement On Liquefied Lateral Spread Ground By Shaking Table Tests

China is a country prone to earthquakes.In the past period of time,there have been many major earthquakes.These earthquakes have caused huge damages to buildings,transportation,water conservancy and brought insignificant casualties and economic losses.Earthquakes are easy to cause liquefaction of the soil,the lateral flow produced by liquefied soil is extremely destructive to buildings,especially to the pile foundations and viaducts of buildings.Therefore,the geotechnical engineering community pays more and more attention to the research on the problem of the liquefaction expansion site under the action of earthquake.Scholars at home and abroad have carried out a lot of research on the problem of the liquefaction expansion site,including the shaking table test,the centrifuge test,and the numerical simulation,there are few achievements,and the emergence of rigid drainage piles provides a new idea and method for the management of liquefaction expansion sites.In this paper,a new type of rigid drainage pipe pile is adopted,which not only has drainage function,but also has good bearing capacity,and carried out the shaking table pile group test on the liquefaction expansion site.Comprehensive verification of the performance of drainage pipe piles provides a better reference and ideas for solving the actual problems of the lateral expansion site of liquefaction,and perfects the pile group test of the lateral expansion site of liquefaction.The main research contents and results of this paper are as follows:(1)Analyzed the macroscopic phenomenon of shaking table test,compared the difference of the displacement of the quay wall,the settlement of the foundation and the displacement of the pile cap between the drainage pile foundation and the ordinary pile foundation,and obtained that the drainage pipe pile has a significant effect on the treatment of the liquefaction expansion site.An effective reinforcement measure,and explored the influence of the foundation slope shoulder distance and relative density on the liquefaction expansion site.(2)The law of excess pore pressure ratio of drainage pile and ordinary pile foundation was explored,and the time history curve of excess pore pressure ratio under different dynamic acceleration peak sine waves was studied.It was obtained that the drainage pipe pile can effectively reduce the pore pressure and prevent soil Body liquefaction,the vertical and horizontal spatial distribution of the excess pore pressure ratio,and the influence of relative compactness;the time history curve of the excess pore pressure ratio under the action of the far-field and near-field seismic waves of three kinds of seismic waves is studied,and the far-field is obtained The influence of waves is more significant and the law of excess pore pressure ratio changes with seismic intensity.(3)Analyzed the bending moments of the drainage piles and ordinary piles,studied the time-history curves of the bending moments of the drainage piles and ordinary piles at different positions,and obtained the development law of the bending moments of the piles at different positions;explored the bending moment The pile depth distribution law shows that the drainage pile can effectively reduce the turning moment and optimize the force of the pile group system.The influence of the relative compactness of the foundation,the slope shoulder distance and the seismic wave characteristics on the pile moment in the liquefied expansion site is studied.(4)Analyzed the acceleration of drainage piles and ordinary pile foundations.Under the action of earthquake,drainage piles can significantly reduce the degree of foundation liquefaction,the distribution of liquefied soil layers,and the influence of different conditions on the acceleration amplification factor.