Study On Damage Of Single Pile And Pile Group By Normal Faluting

A large number of case studies show that the activities of hidden faulting in earthquakes have caused different damage to pile foundations,and it is not clear that the failure mechanism of pile foundations which near faulting.Numerical analyses were therefore conducted in this study to inviestugate the damage of single pile and pile group caused by normal faulting in sand stratum soil,and determine the setback distance of single pile and pile group.Based on the understanding of mechanism,a theoretical model was developed for prediction of single pile deformation induced by normal faulting.Numercial model considering soil strain softening established by finite difference software FLAC3D,was based on the published centrifuge test of single pile and pile group in normal faulting in sand stratum soil.Further research on the different pile positions of single pile and pile group cap,supplements and enriches the data which can not be observed or lacks in experimental.the setback distance of single pile is 20m on the footwall and15m on the hangingwall when the depth of bedrock is 20.0m,The setbak distances of pile group foundation on the hangingwall and footwall are 23.5m and 15.9m,respectively.Load redistribution will occur in shear zone of normal faulting,which is necessary to aviod.Dimensional analysis was conducted in study various factors including displacement amount of hangingwall,soil thickness,pile length in soil and so on,effecting single pile and pile group in normal faulting.Result shows that the displacement amount of hangingwall in normal faulting mainly affects the deformation level of single pile and pile group foundation,but does not affect their setback distance.It is proposed that the effect of the pile position under different soil thickness can be considered comprehensively by using position angle?.It is concluded that the setback angle of single pile and pile group could be?<25° and?<127°.End-bearing piles are more vulnerable to bending and compression damage than friction piles in shear zone.The load redistribution of pile groups in normal faulting is more significant with the increase of pile spacing.No matter in single pile or pile group,pile diameter and load parameters have less influence on them by normal faulting,and other parameters are preferred when considering the setback distance.Based on Analytical approach for estimating ground deformation profile induced by normal faulting,the theoretical calculation method of single pile deformation caused by normal faulting was studied by combining p-y curve and two-parameter elastic foundation beam method.The results show that the horizontal displacement of a single pile by a normal faulting can be divided into the coordinated horizontal displacement of pile and soil,and the reverse horizontal displacement of soil resistance.The theoretical calculation method can better simulate the pile horizontal deformation curve in the stationary zone and rigid body zone.