This research focuses on the application of three soft computing techniques including Minimax Probability Machine Regression(MPMR),Particle Swarm Optimization based Artificial Neural Network(ANN-PSO)and Particle Swarm...This research focuses on the application of three soft computing techniques including Minimax Probability Machine Regression(MPMR),Particle Swarm Optimization based Artificial Neural Network(ANN-PSO)and Particle Swarm Optimization based Adaptive Network Fuzzy Inference System(ANFIS-PSO)to study the shallow foundation reliability based on settlement criteria.Soil is a heterogeneous medium and the involvement of its attributes for geotechnical behaviour in soil-foundation system makes the prediction of settlement of shallow a complex engineering problem.This study explores the feasibility of soft computing techniques against the deterministic approach.The settlement of shallow foundation depends on the parametersγ(unit weight),e0(void ratio)and CC(compression index).These soil parameters are taken as input variables while the settlement of shallow foundation as output.To assess the performance of models,different performance indices i.e.RMSE,VAF,R^2,Bias Factor,MAPE,LMI,U(95),RSR,NS,RPD,etc.were used.From the analysis of results,it was found that MPMR model outperformed PSO-ANFIS and PSO-ANN.Therefore,MPMR can be used as a reliable soft computing technique for non-linear problems for settlement of shallow foundations on soils.展开更多
In densely built-up Singapore,relatively stiffsecant-bored piles and diaphragm walls are commonly used in cut-and-cover works to minimize the impact of ground movement on the adjacent structures and utilities.For exca...In densely built-up Singapore,relatively stiffsecant-bored piles and diaphragm walls are commonly used in cut-and-cover works to minimize the impact of ground movement on the adjacent structures and utilities.For excavations in stiffresidual soil deposits,the asso-ciated wall deflections and ground settlements are generally smaller than for excavations in soft soil deposits.However,if the residual soil permeability is high and the underlying rock is highlyfissured or fractured,substantial groundwater drawdown and associated seepage-induced settlement may occur.In this study,the excavation performance of four sites in residual soil deposits with maximum excavation depths between 20 and 24 m is presented.The maximum wall deflections were found to be relatively small compared to the significantly larger maximum ground settlements,owing to the extensive lowering of the groundwater table.In this paper,details of the subsurface conditions,excavation support system,field instrumentation,and observed excavation responses are presented,with particular focus on the large groundwater drawdown and associated ground settlement.Specific issues encountered during the excavation,as well as the effectiveness of various groundwater control measures,are discussed.The case studies will provide useful references and insights for future projects involving braced excavations in residual soil.展开更多
Extensive site investigations were conducted prior to the construction of a Mass Rapid Transit project in Singapore that was predominantly in the Bukit Timah Granite(BTG)formation residual soil.This paper evaluates th...Extensive site investigations were conducted prior to the construction of a Mass Rapid Transit project in Singapore that was predominantly in the Bukit Timah Granite(BTG)formation residual soil.This paper evaluates the engineering properties of the BTG formation residual soil based on data from 208 site investigation boreholes from four different sites.Based on the results from 2481 conventional laboratory tests and 1192 in-situ tests,this paper summarizes the engineering properties of the highly variable BTG residual soil,including conventional composition analysis,index and hydraulic properties,and strength and deformation parameters required for geotechnical analysis and design.Based on these results,the BTG formation is found to be quite heterogeneous.As the degree of weathering decreases with depth from the top of the formation,the BTG residual soil becomes sandier,with reduced silt and clay fractions.The coefficient of permeability and the compression index of the BTG residual soil vary significantly.In addition,the empirical equations relating the shear strength(index)to the standard penetration test(SPT)-N,as well as the equations and charts for determining stiffness,are proposed.These findings,together with the proposed equations or charts,can be used for design guidance of similar projects related to granitic residual soils in Singapore.展开更多
基金financially supported by High-end Foreign Expert program(G20190022002)Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJZDK201900102)Chongqing Construction Science and Technology Plan Project(2019-0045),that are gratefully acknowledged。
文摘This research focuses on the application of three soft computing techniques including Minimax Probability Machine Regression(MPMR),Particle Swarm Optimization based Artificial Neural Network(ANN-PSO)and Particle Swarm Optimization based Adaptive Network Fuzzy Inference System(ANFIS-PSO)to study the shallow foundation reliability based on settlement criteria.Soil is a heterogeneous medium and the involvement of its attributes for geotechnical behaviour in soil-foundation system makes the prediction of settlement of shallow a complex engineering problem.This study explores the feasibility of soft computing techniques against the deterministic approach.The settlement of shallow foundation depends on the parametersγ(unit weight),e0(void ratio)and CC(compression index).These soil parameters are taken as input variables while the settlement of shallow foundation as output.To assess the performance of models,different performance indices i.e.RMSE,VAF,R^2,Bias Factor,MAPE,LMI,U(95),RSR,NS,RPD,etc.were used.From the analysis of results,it was found that MPMR model outperformed PSO-ANFIS and PSO-ANN.Therefore,MPMR can be used as a reliable soft computing technique for non-linear problems for settlement of shallow foundations on soils.
文摘In densely built-up Singapore,relatively stiffsecant-bored piles and diaphragm walls are commonly used in cut-and-cover works to minimize the impact of ground movement on the adjacent structures and utilities.For excavations in stiffresidual soil deposits,the asso-ciated wall deflections and ground settlements are generally smaller than for excavations in soft soil deposits.However,if the residual soil permeability is high and the underlying rock is highlyfissured or fractured,substantial groundwater drawdown and associated seepage-induced settlement may occur.In this study,the excavation performance of four sites in residual soil deposits with maximum excavation depths between 20 and 24 m is presented.The maximum wall deflections were found to be relatively small compared to the significantly larger maximum ground settlements,owing to the extensive lowering of the groundwater table.In this paper,details of the subsurface conditions,excavation support system,field instrumentation,and observed excavation responses are presented,with particular focus on the large groundwater drawdown and associated ground settlement.Specific issues encountered during the excavation,as well as the effectiveness of various groundwater control measures,are discussed.The case studies will provide useful references and insights for future projects involving braced excavations in residual soil.
基金the support from the National Natural Science Foundation of China(No.51608071)General Financial Grant of the China Postdoctoral Science Foundation(2017M620414)+2 种基金Special Funding for Post-doctoral Researchers in Chongqing(Xm2017007)the Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering,Ministry of Education(RMHSE1601)the Advanced Interdisciplinary Special Cultivation program(No.106112017CDJQJ208850).
文摘Extensive site investigations were conducted prior to the construction of a Mass Rapid Transit project in Singapore that was predominantly in the Bukit Timah Granite(BTG)formation residual soil.This paper evaluates the engineering properties of the BTG formation residual soil based on data from 208 site investigation boreholes from four different sites.Based on the results from 2481 conventional laboratory tests and 1192 in-situ tests,this paper summarizes the engineering properties of the highly variable BTG residual soil,including conventional composition analysis,index and hydraulic properties,and strength and deformation parameters required for geotechnical analysis and design.Based on these results,the BTG formation is found to be quite heterogeneous.As the degree of weathering decreases with depth from the top of the formation,the BTG residual soil becomes sandier,with reduced silt and clay fractions.The coefficient of permeability and the compression index of the BTG residual soil vary significantly.In addition,the empirical equations relating the shear strength(index)to the standard penetration test(SPT)-N,as well as the equations and charts for determining stiffness,are proposed.These findings,together with the proposed equations or charts,can be used for design guidance of similar projects related to granitic residual soils in Singapore.
