Study On The Parameter Inversion And The Adjustment Of The Predicted Deformation Of Three-dimensional Foundation Pit Based On Isight Platform

In foundation pit engineering,due to the complexity of natural soil itself,the soil parameters obtained from exploration are usually not accurate,making numerical simulation analysis unable to be effectively implemented in foundation pit engineering research.With the introduction and development of back analysis technology,combined with on-site monitoring data and numerical analysis methods,accurate soil parameter values can be derived based on parameter sensitivity analysis,and subsequent deformation of foundation pits can be predicted.However,in previous studies,due to the numerous parameters involved in the foundation pit model,the corresponding parameter sensitivity analysis is often limited to a few specified parameters,which cannot comprehensively and objectively reflect the actual engineering situation;Due to the limitations of computational resources,most inversion analyses also use two-dimensional plane strain models,which cannot consider the three-dimensional effects in practical engineering;In addition,existing research has mostly focused on using inversion parameters to predict the deformation of foundation pits in subsequent construction steps.The advantages of the established inversion optimization model have not been fully utilized,and it is necessary to further carry out corresponding optimization and regulation research in response to potential adverse situations that may be predicted.This article takes the TNEC foundation pit project as a case study,combines on-site monitoring data and relies on the Isight optimization design platform to conduct a comprehensive quantitative parameter sensitivity analysis and multi-objective parameter inversion analysis on soil parameters,and predicts the deformation situation of the subsequent excavation stage of the foundation pit.On this basis,the adjustment method of support axial force is explored,and the deformation of foundation pit can be adjusted in advance when the predicted deformation of foundation pit is too large.The main contents and conclusions of this paper are as follows:1.Basic overview of the project.A brief description was provided on the site conditions,soil layer distribution,construction plan,measurement point layout,and a brief analysis was conducted on the measured data at the main monitoring locations in the project.In order to gain a deeper understanding of the engineering situation,research on TNEC foundation pit engineering has been classified and summarized.2.Multi parameter sensitivity analysis.A two-dimensional numerical model of the foundation pit was established considering the actual engineering situation.The optimal Latin hypercube test scheme was adopted on the Isight platform,and a comprehensive quantitative sensitivity analysis was conducted on the soil parameters at each excavation stage.Using the results of quantitative sensitivity analysis,the inversion parameters under various operating conditions were selected as the basis for parameter inversion,and the rationality of the selected inversion parameters was demonstrated.3.Multi objective parameter inversion and prediction of three-dimensional foundation pit deformation.A three-dimensional numerical model was established considering the three-dimensional spatial effects during actual construction,and after continuous optimization,its calculation accuracy and efficiency met the requirements of inversion calculation.According to the selected inversion parameters and the combinatorial optimization method,the multi-objective optimization inversion of soil parameters was carried out.The accuracy of inversion results and prediction results is verified by error function and paired sample T test.At the same time,in-depth exploration was conducted on the inversion parameters and the prediction of foundation pit deformation.It was found that the parameters obtained from inversion are not unique and the stronger the parameter sensitivity,the closer the inversion value is to the true value.The most accurate prediction of foundation pit deformation is in the adjacent next stage.4.Exploring the method of adjusting the axial force of foundation pit support.On the basis of parameter inversion and deformation prediction in the early stage,an optimization analysis was carried out with the deformation of the foundation pit as the target and the support axial force as the optimal variable,and a feasible adjustment method for the support axial force was explored.By increasing the axial force to exert the active support function of the support,providing specific reference values for pre applied axial force,timely response measures can be taken to control the deformation of the foundation pit within the allowable range when the predicted deformation value of the foundation pit exceeds the control value.