Deep Foundation Finite Element Simulation And Behavior Analysis Of A Pile Anchor Support

Pile-anchor retaining structure is a new type of foundation pit supportingstructure which was developed in the1980s. Because it can constraint the soildeformation better and improve the stability of the soil, It has been gradually widelyused in the engineering (excavation, slope, etc.).Supporting structure is mainly designed by static equilibrium method, elasticfoundation beam method and numerical analysis method. Numerical analysis is themost promising method because of it makes up the limitations of the former two.Domestic and foreign scholars have had carried out a wide range of researches on thismethod and achieved lots of achievements. Due to the complexity of the force,coupled with the constitutive relation and contact and other factors which caninfluence the stability of pile-anchor retaining structure, the implementation andapplication of numerical methods still has some difficulties in the actual engineering.Especially the researches about pile-anchor retaining structure under anchor failureand overbreak are much fewer.This thesis makes a three-dimensional simulation of the whole process ofconstruction of a deep foundation pile-anchor supporting engineering using collectingof previous data, field monitoring and finite element analysis software ABAQUSsimulation and other technologies, studying on changes of supporting structure andsoil’force and deformation. And, the simulation results and were compared,analysing on the reasons about the differences between them, verifing the reliabilityof the finite element simulation to this engineering. On this basis, this thesis makes asimulation analysis about a pile-anchor support deep foundation pit under anchorfailure. The conclusions are as follows:1.Making comparison between the results calculated according to the standardsand the actual monitoring results, it shows that: The former is not only difficult toreflect the dynamic changes of the pit in the construction process, but can’t reflect thepit itself has a strong spatial effect.2.Plastic model of Mohr-Coulomb and Drucker-Prager hardening model cansimulate the characteristics of the soil well in this engineering. 3.Excavation simulation shows that: The changes regional of soil body stressbecause of excavation is about1.5times of the excavation depth in horizontaldirection and is about1times of the excavation depth in vertical direction; the soildisplacement changes regional caused by excavation is about3times of theexcavation depth in horizontal direction,the resilisence value of the pit bottom soilmainly depends on the soil behavior.4.Compared the plane frame finite element method calculation results, the actualmonitoring results and the finite element simulation results: the three-dimensionalsimulation is much closer to the actual situation, it could truly reflect the dynamicchanges of the whole process excavation construction.5Anchor failure simulation shows: The upper anchor rope bears much moreforce when the pit has double-row anchor rope. The same row anchor bear unevenforce, the anchor rope of middle endure more than the anchor rope of both ends. So itfurther put forward the concept of the female angle stability region in which thesupporting structure could adjust appropriately.