Deep Foundation Pit Deformation Monitoring And Finite Element Analysis Based On Midas

In recent years,the technology of BIM(Building Information Modeling)has been continuously developed and applied more and more widely in the field of architectural engineering,but its application in foundation pit engineering is still in the primary stage.Midas GTS is a kind of finite element analysis software used in geotechnical engineering and widely used in foundation pit engineering.Taking a wanda deep foundation pit engineering as an example,the innovation point lies in the BIM technology combined with finite element analysis software,through the BIM core Revit modeling software based on foundation pit supporting plan and foundation pit supporting design to modeling of foundation pit,provides a foundation pit information model,contains all kinds of information through the model of visualization can clear show the project,and model 2 d DWG drawing,derived by appropriate modification and import the Midas GTS,modeling,mesh,construction process simulation and calculation,and the analysis of foundation pit is settlement displacement nephogram,By comparing the cloud chart data corresponding to the six procedures,it is shown that the soil mass at the bottom of the pit will uplift and its deformation will gradually increase as the excavation depth increases.Whether the results obtained by finite element analysis are practical or not needs to be compared with the actual monitoring data in the field,so the foundation pit displacement monitoring should be carried out.Revit software is used for modeling the monitoring point family,visually viewing and optimizing the layout of monitoring points in the foundation pit model.In the actual field engineering,thelayout of monitoring points should be arranged and monitored according to the corresponding positions in the BIM model,including: monitoring the horizontal displacement and vertical displacement of the slope top of the foundation pit,monitoring the horizontal displacement of the retaining structure,and recording the results.By comparing the numerical simulation results with the actual monitoring data,the following conclusions are obtained:First,in this case,the maximum settlement of the slope top of the foundation pit occurred at point B1,the simulated value was-4.6mm,and the actual monitoring value was-5.2mm.The simulated value of settlement at the top of the slope around the foundation pit differs little from the measured value,and the trend is basically the same.The measured value is slightly larger than the simulated value.Second,during the excavation of foundation pit soil layer,the horizontal displacement of the slope top of foundation pit increases continuously.The horizontal displacement of continuous excavation of foundation pit is inhibited by the construction of earth wall.The horizontal displacement of the lateral wall of the foundation pit can be reduced by applying the surface layer of shotcrete and bolt.The horizontal displacement of the position with corner effect is relatively small compared with other positions nearby.Third,in this example,when the foundation pit was just excavated without anchor support,the ground connecting walls replaced by the stiffness of single/double row concrete piles and steel pipe piles all showed displacement to the inner side of the foundation pit,with the largest top and the smallest bottom,presenting a cantilever distribution.As foundation pit excavation of foundation pitdepth,single/double row pile stiffness,such as concrete replacement to the wall to show the triangle to the foundation pit horizontal displacement or parallel rigid body displacement,and such as steel pipe pile stiffness to replace to the wall after applied anchor,is characterized by the wall displacement is constant or gradually to move outside the foundation pit,the wall to highlight the abdomen to the foundation pit.