Design And Numerical Simulation Of Pile-Anchor Retaining Structure For A Deep Foundation Pit In Changchun

As the modernisation of cities continues to accelerate and the population grows by leaps and bounds,there is a paucity of available space in urban centres,so more and more people are looking into the use of underground space.Essential to the development of underground space is the pit envelope,and the envelope is always chosen with safety in mind,while at the same time taking economy,suitability and construction time into account.In the initial selection of the pit support scheme,the national foundation code and local experience should be combined to make a decision.Although this has reasonable engineering conditions,it is also influenced by personal empiricism and subjective judgement,so it is necessary to have a scientific theory as the basis for the selection of the pit scheme and to establish a multiple evaluation system.It is of great importance to understand the overall deformation trend of the enclosure structure during the excavation of the pit by taking on-site monitoring data and simulating data for comparison,for the stability of the enclosure structure and the safety of the pit.This paper uses the Jilin Provincial People’s Hospital medical complex deep foundation pit project as an example,and uses the finite element simulation software Midas GTS to carry out numerical simulations.The changes in the horizontal and vertical displacements of the pit and the vertical settlement of the surrounding buildings during the excavation are analysed by the software simulation.Prior to the excavation of the pit,finite element simulation software can be used to predict the displacement of the pit,the location of the maximum amount of soil uplift and the settlement of the surrounding buildings.The results obtained through the software can provide some reference for the setting of foundation pit monitoring points.The main research results are as follows.1.This paper gives a detailed explanation of the research background,significance and development prospect of foundation pit engineering,and describes the categories of foundation pit support,the calculation of earth pressure theory and the calculation method of pile and anchor support.2.Taking the deep foundation pit of the medical complex building of Jilin province People Hospital as the research object,using the simulation software to restore the whole construction process,the horizontal displacement of the retaining piles and the settlement trend of the surrounding buildings are obtained.It can be concluded that the vertical settlement of the adjacent Foundation Pit Building A12 monitoring point is the largest,and the surrounding buildings are all settlement-sensitive areas.By comparing the simulation results with the monitoring results,we can see that the monitoring results are slightly larger than the simulation results,it can be seen that the simulation software can well predict the deformation of the foundation pit.3.By adjusting parameters such as the position of the first row of anchor cables,the pile diameter and the pile spacing,the degree of influence of changing each factor on the deformation of the pit and the settlement of the surrounding buildings is studied.The simulation results show that the influence of changing the size of the pile spacing on the deformation of the pit and the settlement of the surrounding buildings is minimal.