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Estimation of diaphragm wall deflections for deep braced excavation in anisotropic clays using ensemble learning

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Geoscience Frontiers 2021年第1期12卷 365-373页

作者： Runhong Zhang Chongzhi Wu Anthony T.C.Goh Thomas Bohlke Wengang Zhang School of Civil Engineering Chongqing UniversityChongqing400045China School of Civil and Environmental Engineering Nanyang Technological University639798Singapore Institute of Engineering Mechanics Karlsruhe Institute of Technology(KIT)Kaiserstraße 1076131KarlsruheGermany Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing UniversityMinistry of EducationChongqing400045China

This paper adopts the NGI-ADP soil model to carry out finite element analysis,based on which the effects of soft clay anisotropy on the diaphragm wall deflections in the braced excavation were *** than one thousand finite element cases were numerically analyzed,followed by extensive parametric *** models were developed via ensemble learning methods(ELMs),including the e Xtreme Gradient Boosting(XGBoost),and Random Forest Regression(RFR)to predict the maximum lateral wall deformation(δhmax).Then the results of ELMs were compared with conventional soft computing methods such as Decision Tree Regression(DTR),Multilayer Perceptron Regression(MLPR),and Multivariate Adaptive Regression Splines(MARS).This study presents a cutting-edge application of ensemble learning in geotechnical engineering and a reasonable methodology that allows engineers to determine the wall deflection in a fast,alternative way.

关键词： Anisotropic clay NGI-ADP wall deflection Ensemble learning eXtreme gradient boosting Random forest regression

Influence of groundwater drawdown on excavation responses e A case history in Bukit Timah granitic residual soils

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第5期10卷 856-864页

作者： Wengang Zhang Wei Wang Dong Zhou Runhong Zhang A.T.C. Goh Zhongjie Hou National Joint Engineering Research Center of Geohazards Prevention in Reservoir Area Environment Chongqing University Chongqing 400045 China School of Civil Engineering Chongqing University Chongqing 400045 China School of Civil and Environmental Engineering Nanyang Technological University 639798 Singapore

Performances of a braced cut-and-cover excavation system for mass rapid transit （MRT） stations of the Downtown Line Stage 2 in Singapore are presented. The excavation was carried out in the Bukit Timah granitic （BTG） residual soils and characterized by significant groundwater drawdown, due to dewatering work in complex site conditions, insufficient effective waterproof measures and more permeable soils. A two-dimensional numerical model was developed for back analysis of retaining wall movement and ground surface settlement. Comparisons of these measured excavation responses with the calculated performances were carried out, upon which the numerical simulation procedures were calibrated. In addition, the influences of groundwater drawdown on the wall deflection and ground surface settlement were numerically investigated and summarized. The performances were also compared with some commonly used empirical charts, and the results indicated that these charts are less applicable for cases with significant groundwater drawdowns. It is expected that these general behaviors will provide useful references and insights for future projects involving excavation in BTG residual soils under significant groundwater drawdowns.

关键词： Braced excavation Bukit Timah granitic (BTG) residual soil wall deflection Groundwater drawdown Empirical charts

Numerical evaluation of the ground response induced by dewatering in a multi-aquifer system

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Geoscience Frontiers 2021年第5期12卷 384-396页

作者： Yong-Xia Wu Qian Zheng Annan Zhou Shui-Long Shen College of Mechanical and Automotive Engineering Shanghai University of Engineering ScienceShanghai 201620China Department of Civil and Environmental Engineering College of EngineeringShantou UniversityShantouGuangdong 515063China Civil and Infrastructure Engineering School of EngineeringRoyal Melbourne Institute of Technology(RMIT)Victoria 3001Australia MOE Key Laboratory of Intelligent Manufacturing Technology College of EngineeringShantou UniversityShantouGuangdong 515063China

This study presents a numerical investigation of dewatering-induced settlement and wall deflection during pumping tests in Tianjin,*** on the measured groundwater head and building settlement during the pumping test,a three-dimensional liquid-solid coupling model is established by using the finite element method(FEM).The void ratio,hydraulic conductivity,and elastic modulus of each layer are back-calculated through the numerical *** groundwater drawdown,seepage field,ground settlement,horizontal ground displacement,and diaphragm wall lateral deflection are analyzed using the FEM *** simulated results demonstrate that(i)the maximum ground settlement outside of the excavation reaches to 82 mm due to the leakage effect of aquitards;(ii)large horizontal displacement occurs in the soil during the pumping test with a maximum value of 28.3 mm,and the installation of the diaphragm wall in the aquifer can reduce the horizontal displacement of the ground;(iii)long-term pumping causes a large lateral deflection of the diaphragm wall,and a maximum value of 23.2 mm occurs at the layer where the screens of the wells are located;and(iv)long-term large-scale pumping should be avoided before excavation.

关键词： Excavation pit Pumping test Settlement wall deflection Numerical simulation

An intelligent procedure for updating deformation prediction of braced excavation in clay using gated recurrent unit neural networks

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第6期13卷 1485-1499页

作者： Jie Yang Yingjing Liu Saffet Yagiz Farid Laouafa Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityHong KongChina Zhongtian Construction Group Co.Ltd. Hangzhou310008China School of Mining and Geosciences Nazarbayev UniversityNur-Sultan010000Kazakhstan National Institute for Industrial Environment and Risks(INERIS) Verneuil-en-HalatteFrance

This paper aims to establish an intelligent procedure that combines the observational method with the existing deep learning technique for updating deformation of braced excavation in *** gated recurrent unit(GRU) neural network is adopted to formulate the forecast model and learn the potential rules in the field observations using the Nesterov-accelerated Adam(Nadam) *** the proposed procedure,the GRU-based forecast model is first trained based on the field data of previous and current ***,the field data of the current stage are used as input to predict the deformation response of the next stage via the previously trained GRU-based forecast *** updating process will loop up till the end of the *** procedure has the advantage of directly predicting the deformation response of unexcavated stages based on the monitoring *** proposed intelligent procedure is verified on two well-documented cases in terms of accuracy and *** results indicate that both wall deflection and ground settlement are accurately predicted as the excavation ***,the advantages of the proposed intelligent procedure compared with the Bayesian/o ptimization updating are illustrated.

关键词： Braced excavation Deep learning Clay wall deflection Ground settlement Deformation updating