| Limited by both shape of buildings and site, more and more arc foundation pit and other irregularlyshaped foundation pit appeared gradually. Arc foundation pit had a concave internal arch wall. Because ofthe earth pressure, a pressure produced on the internal of the supporting structure. The compressive strengthof the supporting structure was good. And even if there was some weak connection links, such as the finecrack of diaphragm retaining walls etc, which will be more tightly by the pressure produced. So the arceffect is advantageous to both the stability and deformation. Because it can bear the external forcerationally, it will be a hot problem to be studied sustained.It is inability to calculate spatial effect by plane shape with2d finite element method and traditionalanalysis method. finite element software existing was limited to solve plane problems. It can not reflectspace deformation behavior practically for excess simplification when simulation calculation on deepfoundation pit with obviously spatial effect. Therefore, there maybe exist potential safety hazard andresource waste potentially. So it is essential to solve supporting structure as spatial problems whensimulation calculation on deep foundation pit with obviously spatial effect.It turns plan problems to three-dimensional problems to realize as the development of computer abilityand large scale general finite element software in engineering design fast maturity. It can be simulatedspace displacement field at lateral foundation pit in different cases and forecast of deformation and internalforce dynamic changes to build three-dimensional finite element model of foundation pit supportingstructure. But it is complicated to build model and the calculation time is long and hard to convergencewhen the finite element software used. It is helpful to grasp the structure stress characteristic and spacedeformation behavior to build element model with the three-dimensional elastic supporting method on thewhole. The results that the horizontal displacement and the internal force of the Support system andretaining structures in each excavation condition can be obtained. At the same time, it is greatly reducedworkload that to consider soil structure interaction with the three-dimensional finite element analysis. Thusis easy to be applied in practical project design.First, this paper summarizes the current characteristics of deep excavation foundation pit engineering and shortages existed in the research, Study on some basic theory of arc deep foundation pit engineering.Then several kinds of numerical analysis methods of the deep foundation pit engineering wereintroduced. the advantages and disadvantages of the several calculation methods were compared. Using ofANSYS software, according to a Zhengzhou arc deep foundation pit project actual situation, based on theassumption, the finite element model was built with three-dimensional elastic supporting method. Elementbirth and death and load step are used to simulate the excavation process. And the calculation method wasintroduced in detail. The horizontal displacement of the arc segment and line segment was Calculated andto be analyzed.Finally, the calculated and measured values are compared and analyzed, study the applicability ofelastic supporting method in simulation on excavation of arc deep foundation pit.The results show that, it can reflect the actual structure of the space deformation behavior withthree-dimensional elastic supporting method to simulate and analysis arc deep excavation foundation pit.Its spatial effect can be simulated effectively. the distribution and the change of the results of calculationand measurement agrees well, It proved that using three-dimensional elastic supporting method to simulatearc deep excavation process is feasibility. Comparing with straight line, the displacement of arc segment issmall relatively, and the operating changes little, the range with deep pile changes is more stable, the locallarge displacement was reduced. |
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