Study On The Application Of Stiff Pile-Anchor Supporting Technique In The Deep Foundation Pit Of Hefei Guanzhuli

The human society increases demand for civil air defense,underground commercial underground car parks owing to the rapid development of the city,the construction space more and more to the underground development tendency.When building the underground space,it will involve the excavation problem.Compared with other supporting structures,pile-anchor united support can more effectively control the deformation of the supporting structure,which is convenient,reliable and can achieve the high economic benefit,which makes it used widely in foundation pit support.This paper,based on Hefei Guanzhuli deep foundation pit,analysed the reasonability of the stiff pile-anchor support system by monitoring data.For the design of stiff-pile with no standard,the support system were simulated by Midas to research the possibility of numerical simulation method for stiff-pile design by comparing of design results and further research on the checking calculation of the stiff-pile.The results show that the stiff pile-anchor supporting system is appropriate for Hefei Guanzhuli deep foundation pit which has a good supporting effect.The comparison of the design results and numerical simulation results shows that the numerical simulation results of the vertical stress,displacement and the axial force of the bolt are basically the same as the design results,and are in good agreement with the actual engineering which compared with the actual monitoring results.Therefore,numerical simulation method can be used for stiff-pile design,and it can achieve advanced prediction especially in the study of the influence of foundation pit excavation on the surrounding environment,which the design software can’t achieve.However,the numerical simulation results show that the horizontal stress and internal force results are different from the design results,it is obvious that the design theory used in the specification is conservative.For the design checking calculation of the stiff-pile,the expression of bending capacity of stiff-pile are derived by referring basic assumptions of design of concrete structures,and the accuracy of the formula is verified by numerical simulation and example calculation,it can provide the reference for the design of stiff pile.