Numerical And Project Analysis Of Multi-layer Prestressed Anchor Cables And Retaining Piles Based On FLAC3D

With the rapid development of our country’s economic construction, utilizationof high-rise buildings and underground space speed up increasingly, with variouslarge-scale engineering projects spring up constantly as well. And how to design theretaining structure for deep foundation pit engineering has become an importantproblem. Due to the feature of good effect of stability against sliding, simplicity andconvenience of construction, low demand of engineering site, the pile-anchorretaining structure has become widely used in deep foundation. However, thecalculation method of this new structure is not mature yet and the present calculati onmodel hardly reflects the practical stress features, which cuases to the theory falls farbehind engineering practice. Therefore, to carry out research on this aspect is ofsignificant practical value. For this reason, engineering properties, calculation anddesign methods for the structure of retaining piles with multi-layer prestressed anchorcables were investigated in this paper. Furthermore, a thorough study about the innerforces and displacement distribution of the pile-soil-anchor system as well as thoseinfluencing factors was done by the numerical analysis. And the correspondingconstruction technology for this kind of retaining structure was also discussed. Theaforementioned work is mainly as follows:Firstly, combined with the available theoretical research, experiment data andnumerical analysis results, the development progresss, characteristic and supportingmethod, the engineering features of deep foundation pit engineering as well as thepresent research status of pile-anchor retaining structure were summarized in detail.Then, according to the feature of the multi-layer supporting anchor and retaining pilestructure, the calculation method of pile anchor retaining structure was discussed andstudied respectively. And some reasonable construction techniques and points to be bepaid attention for the multi-layer prestressed anchor cables and retaining pile structurewere proposed for reference by engineering practice.Secondly, based on the Mohr-Coulomb failure criterion, various constitutivemodels of pile, soil and anchor cable as well as the model parameters, the FLAC3Dwas introduced to set up a numerical model for the multi-layer prestressed anchorcables and retaining pile structure, in which influences by initial stress field anddifferent working conditions were taken into account. After a series of comparativeanalysis, stress-strain distribution and changing rules of the pile-anchor support system during the process of step-by-step excavation and support were obtained.Moreover, the variation of the inner forces and displacement of pile, soil, and anchorcables as well as those influencing factors were discussed in detail through aparameter analysis.Finally, the present method was applied to a deep foundation pit engineeringproject, of which the west side was supported by the pile-anchor retaining structure.Based on the numerical modeling analysis, horizontal and vertical displacement onthe pile top, distribution and magnitude of the inner and outer steel stress, andbending moment along the pile were obtained. Compared with the measured field data,a good agreement was found between the calculated results and measured results,which can provide a reference for engineering practice.