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Constitutive model for overconsolidated clays

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Science China(Technological Sciences) 2008年第2期51卷 179-191页

作者： YAO YangPing HOU Wei zhou annan Department of Civil Engineering Beihang UniversityBeijing 100083China

Based on the relationships between the Hvorslev envelope,the current yield sur-face and the reference yield surface,a new constitutive model for overconsolidated clays is proposed. It adopts the unified hardening parameter,to which the potential failure stress ratio and the characteristic state stress ratio are introduced. The model can describe many characteristics of overconsolidated clays,including stress-strain relationships,strain hardening and softening,stress dilatancy,and stress path dependency. Compared with the Cam-clay model,the model only re-quires one additional soil parameter which is the slope of the Hvorslev envelope. Comparisons with data from triaxial drained compression tests for Fujinomori clay show that the proposed model can rationally describe overconsolidated properties. In addition,the model is also used to predict the stress-strain relationship in the isotropic consolidation condition and the stress paths in the undrained triaxial compression tests.

关键词： overconsolidated clays current yield surface reference yield surface unified hardening parameter Hvorslev envelope.

Consolidation of partially saturated ground improved by impervious column inclusion:Governing equations and semi-analytical solutions

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第3期14卷 837-850页

作者： Lei Wang annan zhou Yongfu Xu Xiaohe Xia School of Urban Railway Transportation Shanghai University of Engineering ScienceShanghai201620China Civil and Infrastructure Engineering Discipline School of EngineeringRMIT UniversityMelbourne3001Australia Department of Civil Engineering Shanghai Jiao Tong UniversityShanghai200240China

This study focuses on the consolidation behavior and mathematical interpretation of partially-saturated ground improved by impervious column *** constitutive relations for soil skeleton,pore air and pore water for partially saturated soils are proposed in the context of partially-saturated ground improved by impervious column *** equation and dissipation equations of excess pore air/water pressures for a partially saturated improved ground are then *** semi-analytical solutions for ground settlement and pore pressure dissipation are then obtained through the Laplace transform and validated by the existing solutions for two special cases in the literature and the numerical results obtained from the finite difference method.A series of parametric studies is finally conducted to investigate the influence of some key factors on consolidation of partially saturated ground improved by impervious column *** on the parametric study,it can be found that a higher value of the area replacement ratio or modulus of the pile results in a longer dissipation time of excess pore air pressure(PAP),a shorter dissipation time of excess pore water pressure(PWP),and a lower normalized settlement.

关键词： Semi-analytical solution Consolidation Partially saturated soil Ground improvement Impervious column inclusion

Real-time analysis and prediction of shield cutterhead torque using optimized gated recurrent unit neural network

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第4期14卷 1232-1240页

作者： Song-Shun Lin Shui-Long Shen annan zhou Department of Civil Engineering School of Naval ArchitectureOceanand Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China Key Laboratory of Intelligent Manufacturing Technology Department of Civil and Environmental EngineeringCollege of EngineeringShantou UniversityShantou515063China Discipline of Civil and Infrastructure School of EngineeringRoyal Melbourne Institute of Technology(RMIT)MelbourneVictoria 3001Australia Department of Civil and Environmental Engineering National University of Singapore117576Singapore

An accurate prediction of earth pressure balance(EPB)shield moving performance is important to ensure the safety tunnel excavation.A hybrid model is developed based on the particle swarm optimization(PSO)and gated recurrent unit(GRU)neural *** is utilized to assign the optimal hyperparameters of GRU neural *** are mainly four steps:data collection and processing,hybrid model establishment,model performance evaluation and correlation *** developed model provides an alternative to tackle with time-series data of tunnel *** from that,a novel framework about model application is performed to provide guidelines in practice.A tunnel project is utilized to evaluate the performance of proposed hybrid *** indicate that geological and construction variables are significant to the model *** analysis shows that construction variables(main thrust and foam liquid volume)display the highest correlation with the cutterhead torque(CHT).This work provides a feasible and applicable alternative way to estimate the performance of shield tunneling.

关键词： Earth pressure balance(EPB)shield tunneling Cutterhead torque(CHT)prediction Particle swarm optimization(PSO) Gated recurrent unit(GRU)neural network

Generalized non-linear strength theory and transformed stress space

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Science China(Technological Sciences) 2004年第6期47卷 691-709页

作者： YAO Yangping LU Dechun zhou annan ZOU Bo Department of Civil Engineering Beihang UniversityBeijing 100083China

Based on the test data of frictional materials and previous research achievements in this field, a generalized non-linear strength theory (GNST) is proposed. It describes non-linear strength properties on the π-plane and the meridian plane using a unified formula, and it includes almost all the present non-linear strength theories, which can be used in just one material. The shape of failure function of the GNST is a smooth curve between the SMP criterion and the Mises criterion on the π-plane, and an exponential curve on the meridian plane. Through the transformed stress space based on the GNST, the combination of the GNST and various constitutive models using p and q as stress parameters can be realized simply and rationally in three-dimensional stress state. Keywords generalized non-linear strength theory (GNST) - transformed stress - constitutive model - application

关键词： generalized non-linear strength theory (GNST) transformed stress constitutive model application

Prediction of geological characteristics from shield operational parameters by integrating grid search and K-fold cross validation into stacking classification algorithm

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第4期14卷 1292-1303页

作者： Tao Yan Shui-Long Shen annan zhou Xiangsheng Chen MOE Key Laboratory of Intelligent Manufacturing Technology Department of Civil and Environmental EngineeringCollege of EngineeringShantou UniversityShantouGuangdong 515063China Discipline of Civil and Infrastructure School of EngineeringRoyal Melbourne Institute of Technology(RMIT)Victoria3001Australia College of Civil and Transportation Engineering Shenzhen UniversityShenzhenGuangdong 518060China

This study presents a framework for predicting geological characteristics based on integrating a stacking classification algorithm(SCA) with a grid search(GS) and K-fold cross validation(K-CV). The SCA includes two learner layers: a primary learner’s layer and meta-classifier layer. The accuracy of the SCA can be improved by using the GS and K-CV. The GS was developed to match the hyper-parameters and optimise complicated problems. The K-CV is commonly applied to changing the validation set in a training set. In general, a GS is usually combined with K-CV to produce a corresponding evaluation index and select the best hyper-parameters. The torque penetration index(TPI) and field penetration index(FPI) are proposed based on shield parameters to express the geological characteristics. The elbow method(EM) and silhouette coefficient(Si) are employed to determine the types of geological characteristics(K) in a Kmeans++ algorithm. A case study on mixed ground in Guangzhou is adopted to validate the applicability of the developed model. The results show that with the developed framework, the four selected parameters, i.e. thrust, advance rate, cutterhead rotation speed and cutterhead torque, can be used to effectively predict the corresponding geological characteristics.

关键词： Geological characteristics Stacking classification algorithm(SCA) K-fold cross-validation(K-CV) K-means++

Improved prediction of slope stability using a hybrid stacking ensemble method based on finite element analysis and field data

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第1期13卷 188-201页

作者： Navid Kardani annan zhou Majidreza Nazem Shui-Long Shen Civil and Infrastructure Discipline School of EngineeringRoyal Melbourne Institute of Technology(RMIT)MelbourneVictoriaAustralia Department of Civil and Environmental Engineering College of EngineeringShantou UniversityShantou515063China

Slope failures lead to catastrophic consequences in numerous countries and thus the stability assessment for slopes is of high interest in geotechnical and geological engineering researches.A hybrid stacking ensemble approach is proposed in this study for enhancing the prediction of slope *** the hybrid stacking ensemble approach,we used an artificial bee colony(ABC)algorithm to find out the best combination of base classifiers(level 0)and determined a suitable meta-classifier(level 1)from a pool of 11 individual optimized machine learning(OML)*** element analysis(FEA)was conducted in order to form the synthetic database for the training stage(150 cases)of the proposed model while 107 real field slope cases were used for the testing *** results by the hybrid stacking ensemble approach were then compared with that obtained by the 11 individual OML methods using confusion matrix,F1-score,and area under the curve,*** comparisons showed that a significant improvement in the prediction ability of slope stability has been achieved by the hybrid stacking ensemble(AUC?90.4%),which is 7%higher than the best of the 11 individual OML methods(AUC?82.9%).Then,a further comparison was undertaken between the hybrid stacking ensemble method and basic ensemble classifier on slope stability *** results showed a prominent performance of the hybrid stacking ensemble method over the basic ensemble ***,the importance of the variables for slope stability was studied using linear vector quantization(LVQ)method.

关键词： Slope stability Machine learning(ML) Stacking ensemble Variable importance Artificial bee colony(ABC)

Characterisation of likelihood of gas hydrates occurrence in the South China Sea based on Bonferroni mean-based TOPSIS and fuzzy set theory

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Geoscience Frontiers 2023年第2期14卷 59-70页

作者： Pierre Guy Atangana Njock Shui-Long Shen annan zhou MOE Key Laboratory of Intelligent Manufacturing Technology Department of Civil and Environmental EngineeringCollege of EngineeringShantou UniversityGuangdong 515063China Discipline of Civil and Infrastructure Engineering School of EngineeringRoyal Melbourne Institute of TechnologyVictoria 3001Australia

The efficiency of gas hydrate production depends on the success of gas exploration and occurrence *** existing evaluation models are generally univariate and only applicable to certain geological *** study presents a holistic approach to evaluate the likelihood of gas hydrate occurrence by supplying an index for mapping gas hydrate levels with *** approach integrates a generalised TOPSIS method with the fuzzy set *** expedition of gas hydrate conducted in the Shenhu area of the South China Sea was adopted as a case study to assess the reliability of the proposed *** a multivariate model,the proposed approach enables the capture of non-linearity associated with gas hydrates in its *** magnitude of the strength of the influential factor varies substantially from one site to another across the Shenhu *** results also show that no site achieves the highest likelihood‘Level V’.These results are consistent with the gas saturation values obtained using Archie’s *** example,at SH4 and SH7,the values of the likelihood index are the highest between 170–185 m and 150–165 m,respectively,and the observed saturation at these locations varies from 20%(SH4)to 43%(SH7).The proposed likelihood index yields a prominent ability to quantify the level of occurrence of gas hydrates with depth at different *** appears to be an efficient multicriteria system bound to improve the management of the gas production trial stage.

关键词： Gas hydrates South China Sea Geologic controls Occurrence characterization Energy resource

Two-dimensional plane strain consolidation of unsaturated soils considering the depth-dependent stress

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第6期15卷 1603-1614页

作者： Lei Wang Sidong Shen Tianyi Li Minjie Wen annan zhou School of Urban Railway Transportation Shanghai University of Engineering ScienceShanghai201620China Key Laboratory of Soft Soils and Geoenvironmental Engineering of Ministry of Education Zhejiang UniversityHangzhou310058China School of Civil Environmental and Chemical EngineeringRoyal Melbourne Institute of Technology(RMIT)MelbourneVIC3001Australia

In practical engineering,the total vertical stress in the soil layer is not constant due to stress diffusion,and varies with time and ***,the purpose of this paper is to investigate the effect of stress diffusion on the two-dimensional(2D)plane strain consolidation properties of unsaturated soils when the stress varies with time and depth.A series of semi-analytical solutions in terms of excess pore air and water pressures and settlement for 2D plane strain consolidation of unsaturated soils can be derived with the joint use of Laplace transform and Fourier sine series ***,the inverse Laplace transform of the semi-analytical solution is given in the time domain using a self-programmed code based on Crump’s *** reliability of the obtained solutions is proved by the ***,the 2D plots of excess pore pressures and the curves of settlement varying with time,considering different physical parameters of unsaturated soil stratum and depth-dependent stress,are depicted and analyzed to study the 2D plane strain consolidation properties of unsaturated soils subjected to the depthdependent stress.

关键词： Semi-analytical solutions Two-dimensional(2D)plane strain consolidation Unsaturated soils Depth-dependent stress Laplace transform

Modelling the performance of EPB shield tunnelling using machine and deep learning algorithms

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Geoscience Frontiers 2021年第5期12卷 81-92页

作者： Song-Shun Lin Shui-Long Shen Ning Zhang annan zhou Department of Civil Engineering School of Naval ArchitectureOceanand Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China MOE Key Laboratory of Intelligent Manufacturing Technology College of EngineeringShantou UniversityShantouGuangdong 515063China Discipline of Civil and Infrastructure School of EngineeringRoyal Melbourne Institute of Technology(RMIT)Victoria 3001Australia Shanghai Key Laboratory for Digital Maintenance of Buildings and Infrastructure Shanghai Jiao Tong UniversityShanghai 200240China

This paper introduces an intelligent framework for predicting the advancing speed during earth pressure balance(EPB)shield *** artificial intelligence(AI)models based on machine and deep learning techniques-back-propagation neural network(BPNN),extreme learning machine(ELM),support vector machine(SVM),long-short term memory(LSTM),and gated recurrent unit(GRU)-are *** geological and nine operational parameters that influence the advancing speed are considered.A field case of shield tunnelling in Shenzhen City,China is analyzed using the developed models.A total of 1000 field datasets are adopted to establish intelligent *** prediction performance of the five models is ranked as GRU>LSTM>SVM>ELM>***,the Pearson correlation coefficient(PCC)is adopted for sensitivity *** results reveal that the main thrust(MT),penetration(P),foam volume(FV),and grouting volume(GV)have strong correlations with advancing speed(AS).An empirical formula is constructed based on the high-correlation influential factors and their corresponding field ***,the prediction performances of the intelligent models and the empirical method are *** results reveal that all the intelligent models perform better than the empirical method.

关键词： EPB shield machine Advancing speed prediction Intelligent models Empirical analysis Tunnel excavation