Numerical Simulation And Construction Technology Of Hydraulic Test Foundation Pit

With the rapid urbanization and development of technology in China,the building engineering is getting more demanding.Due to the increasing excavation area and depth of foundation pit and more difficult surrounding environment with complicated engineering geological conditions,more and more problems are encountered in the design and construction.At present,deep foundation pit engineering is still an important subject in geotechnical engineering,so further investigation needs to be carried out.In this paper,based on the hydraulic test of deep foundation pit support engineering in Dalian Petrochemical Equipment Co.,Ltd.,the research status of deep foundation pit support structure was briefly summarized,which included numerical simulation,different support structures.Through the comparison of advantages and disadvantages of each type,the selection of support forms had been prepared in this case.The supporting structure of this foundation pit project was optimized by multi-objective analytic hierarchy process and fuzzy comprehensive evaluation.Besides,the key points of construction technology of the secant piles were put forward,and the supporting structure was designed and calculated.The soil and supporting structure in the process of foundation pit construction were studied by field monitoring and numerical simulation.The deformation characteristics of the structure were presented and relevant suggestions were put forward.The following conclusions can be drawn from the study:(1)The multi-objective analytic hierarchy process and fuzzy comprehensive evaluation method were used to select the supporting scheme of the foundation pit.Finally,the scheme of the 1:1 slope with soil nail and net-sprayed concrete inthe upper part and the secant piles and reinforced concrete internal support in thelower part is selected.The supporting effect of the scheme is remarkable.(2)To ensure the progress of the construction,it is necessary to control the deviation of the holes position and the piles position of the secant piles.(3)Based on the monitoring,the variation law of surface settlement,slope displacement and pile body displacement in the construction process was analyzed.The displacement of the slope increased first and then decreased with the construction,and the displacement of the lower part of the slope was larger than the upper,so the support should be strengthened and monitored during the construction.The maximum displacement of the secant piles moved down gradually with the excavations,which was basically located near the excavation surface of the foundation pit.Compared with single piles,the flat deformation was obviously smaller,indicating that the secant piles made itself as an entirety.(4)The Midas GTS / NX finite element software was used to simulate the project.By comparing the results with the measured data,the change trend of the two results was consistent,which verified the rationality of the numerical simulation results in this paper.(5)Through the research of this paper,the deformation law of soil and support structure in the process of foundation pit construction was obtained,which has important guiding significance for the related engineering in the future.