Monitoring Analysis And Numerical Simulation Of Deep Foundation Pit Pile-anchor Supporting Structure System In Loess Areas

Pile-anchor supporting structure has been widely applied in foundation pit engineering due to many advantages,such as simple construction,low cost,smaller working space,better displacement control and high suitability,etc.However,soil mass property is complex and changeable.Furthermore,the theoretical research on pile-anchor supporting structure lags far behind engineering practice,which unable to fulfill the demand of engineering application.Hence,it is still of great practical signification for research on pile-anchor supporting structure stress and deformation mechanism.With a pile-anchor supporting deep foundation pit engineering in Xi'an which is the loess geological conditions as research object,this paper monitors and analyzes its deformation and stress.Meanwhile,it applies ABAQUS,the finite element software,to carry out 3D modeling on this engineering,and conduct a comparison analysis between the computed results and monitoring data,then,some meaningful conclusions are came out.Its main research conclusions are as follows:(1)As the foundation pit being excavated,pile head displacement increases continuously,which is faster in earlier stage,slower in mid-stage and becoming stable in later stage.And displacement near the middle of foundation pit is larger than that near foundation pit corner,long side displacement larger than that of short side.In addition,simulation results show that applying pre-stressed anchor cable can decrease pile head displacement,but the effect of low anchor cable reduces gradually;(2)Pile body deformation becomes larger and larger as the foundation pit being excavated,with the largest displacement in pile head,smallest displacement in pile bottom,and pile body deformation in the middle of foundation pit is generally larger than that in foundation pit corner,which reflects the space effect of foundation pit supporting structure,while indicates that applying pre-stressed anchor cable can restrain the file body deformation very well;(3)As the foundation pit being excavated,anchor cable axial force becomes larger and larger,with the largest increase in the middle of foundation pit;and according to simulation,anchor cable axial force is distributed evenly in free segment,and suddenly decreases in the junction point between segment and anchoring segment,which better reflects the stress mechanism of anchor cable,indicating that the contacting position in this model is comparatively reasonable;(4)According to monitoring data,pile head and earth surface settlement increases gradually;however,simulation results show that,pile head and earth surface displacement is upward,and becomes larger and larger as foundation pit being excavated,which is completely opposite to the reality;(5)according to comparison analysis between monitoring data and simulation results,the finite element software ABAQUS can better simulate the change law of pile head horizontal displacement,pile body deformation and anchor cable axial force,verifying that this method can be widely applied in future engineering practices due to its reliability in simulating foundation pit deformation;...