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Limit load and failure mechanisms of a vertical Hoek-Brown rock slope
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作者 Jim Shiau Warayut Dokduea +1 位作者 Suraparb Keawsawasvong Pitthaya Jamsawang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第3期1106-1111,共6页
The problem considered in this short note is the limit load determination of a vertical rock slope.The classical limit theorem is employed with the use of adaptive finite elements and nonlinear programming to determin... The problem considered in this short note is the limit load determination of a vertical rock slope.The classical limit theorem is employed with the use of adaptive finite elements and nonlinear programming to determine upper and lower bound limit loads of a Hoek-Brown vertical rock slope.The objective function of the mathematical programming problem is such as to optimize a boundary load,which is known as the limit load,resembling the ultimate bearing capacity of a strip footing.While focusing on the vertical slope,parametric studies are carried out for several dimensionless ratios such as the dimensionless footing distance ratio,the dimensionless height ratio,and the dimensionless rock strength ratio.A comprehensive set of design charts is presented,and failure envelopes shown with the results explained in terms of three identified failure mechanisms,i.e.the face,the toe,and the Prandtl-type failures.These novel results can be used with great confidence in design practice,in particularly noting that the current industry-based design procedures for the presented problem are rarely found. 展开更多
关键词 Bearing capacity Rock slope Vertical slope Finite element limit analysis Hoek-Brown yield criterion
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Effects of cement-enhanced soil on the ultimate lateral resistance of composite pile in clayey soil
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作者 Zhijun Yang Kexin Chen +1 位作者 Xudong Fu Zhiyan Zou 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第1期183-191,共9页
The composite pile consisting of core-pile and surrounding cement-enhanced soil is a promising pile foundation in recent years.However,how and to what extent the cement-enhanced soil influences the ultimate lateral re... The composite pile consisting of core-pile and surrounding cement-enhanced soil is a promising pile foundation in recent years.However,how and to what extent the cement-enhanced soil influences the ultimate lateral resistance has not been fully investigated.In this paper,the ultimate lateral resistance of the composite pile was studied by finite element limit analysis(FELA)and theoretical upper-bound analysis.The results of FELA and theoretical analysis revealed three failure modes of laterally loaded composite piles.The effects of the enhanced soil thickness,strength,and pile-enhanced soil interface characteristics on the ultimate lateral resistance were studied.The results show that increasing the enhanced soil thickness leads to a significant improvement on ultimate lateral resistance factor(N P),and there is a critical thickness beyond which the thickness no longer affects the N P.Increasing the enhanced soil strength induced 6.2%-232.6%increase of N P.However,no noticeable impact was detected when the enhanced soil strength was eight times higher than that of the natural soil.The maximum increment of N P is only 30.5%caused by the increase of interface adhesion factor(a).An empirical model was developed to calculate the N P of the composite pile,and the results show excellent agreement with the analytical results. 展开更多
关键词 Composite pile Ultimate soil resistance Finite element limit analysis(FELA) Plasticity theory Failure mode
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Physics-based and data-driven modeling for stability evaluation of buried structures in natural clays 被引量:1
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作者 Fengwen Lai Jim Shiau +3 位作者 Suraparb Keawsawasvong Fuquan Chen Rungkhun Banyong Sorawit Seehavong 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第5期1248-1262,共15页
This study presents a hybrid framework to predict stability solutions of buried structures under active trapdoor conditions in natural clays with anisotropy and heterogeneity by combining physics-based and data-driven... This study presents a hybrid framework to predict stability solutions of buried structures under active trapdoor conditions in natural clays with anisotropy and heterogeneity by combining physics-based and data-driven modeling.Finite-element limit analysis(FELA)with a newly developed anisotropic undrained shear(AUS)failure criterion is used to identify the underlying active failure mechanisms as well as to develop a numerical(physics-based)database of stability numbers for both planar and circular trapdoors.Practical considerations are given for natural clays to three linearly increasing shear strengths in compression,extension,and direct simple shear in the AUS material model.The obtained numerical solutions are compared and validated with published solutions in the literature.A multivariate adaptive regression splines(MARS)algorithm is further utilized to learn the numerical solutions to act as fast FELA data-driven surrogates for stability evaluation.The current MARS-based modeling provides both relative importance index and accurate design equations that can be used with confidence by practitioners. 展开更多
关键词 Buried structures Natural clays Active trapdoor Undrained stability Multivariate adaptive regression splines (MARS) Finite element limit analysis(FELA)
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Strength reduction and step-loading finite element approaches in geotechnical engineering 被引量:23
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作者 Yingren Zheng Xiaosong Tang +2 位作者 Shangyi Zhao Chujian Deng Wenjie Lei 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE 2009年第1期21-30,共10页
The finite element limit analysis method has the advantages of both numerical and traditional limit equilibrium techniques and it is particularly useful to geotechnical engineering.This method has been developed in Ch... The finite element limit analysis method has the advantages of both numerical and traditional limit equilibrium techniques and it is particularly useful to geotechnical engineering.This method has been developed in China,following well-accepted international procedures,to enhance understanding of stability issues in a number of geotechnical settings.Great advancements have been made in basic theory,the improvement of computational precision,and the broadening of practical applications.This paper presents the results of research on(1) the efficient design of embedded anti-slide piles,(2) the stability analysis of reservoir slopes with strength reduction theory,and(3) the determination of the ultimate bearing capacity of foundations using step-loading FEM(overloading).These three applications are evidence of the design improvements and benefits made possible in geotechnical engineering by finite element modeling. 展开更多
关键词 finite element limit analysis method strength reduction step-loading embedded anti-slide piles reservoir slope FOUNDATION
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Finite element analyses of slope stability problems using non-associated plasticity 被引量:10
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作者 Simon Oberhollenzer Franz Tschuchnigg Helmut F.Schweiger 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2018年第6期1091-1101,共11页
In recent years, finite element analyses have increasingly been utilized for slope stability problems. In comparison to limit equilibrium methods, numerical analyses do not require any definition of the failure mechan... In recent years, finite element analyses have increasingly been utilized for slope stability problems. In comparison to limit equilibrium methods, numerical analyses do not require any definition of the failure mechanism a priori and enable the determination of the safety level more accurately. The paper compares the performances of strength reduction finite element analysis(SRFEA) with finite element limit analysis(FELA), whereby the focus is related to non-associated plasticity. Displacement-based finite element analyses using a strength reduction technique suffer from numerical instabilities when using non-associated plasticity, especially when dealing with high friction angles but moderate dilatancy angles. The FELA on the other hand provides rigorous upper and lower bounds of the factor of safety(FoS) but is restricted to associated flow rules. Suggestions to overcome this problem, proposed by Davis(1968), lead to conservative FoSs; therefore, an enhanced procedure has been investigated. When using the modified approach, both the SRFEA and the FELA provide very similar results. Further studies highlight the advantages of using an adaptive mesh refinement to determine FoSs. Additionally, it is shown that the initial stress field does not affect the FoS when using a Mohr-Coulomb failure criterion. 展开更多
关键词 Finite element limit analysis(FELA) Finite element method Slope stability Strength reduction technique Non-associated plasticity Adaptive mesh refinement Initial stresses
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An efficient probabilistic design approach for tunnel face stability by inverse reliability analysis 被引量:4
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作者 Jian Ji Zheming Zhang +3 位作者 Zhijun Wu Jiacheng Xia Yongxin Wu Qing Lüc 《Geoscience Frontiers》 SCIE CAS CSCD 2021年第5期374-383,共10页
In order to maintain the safety of underground constructions that significantly involve geo-material uncertainties,this paper delivers a new computation framework for conducting reliability-based design(RBD)of shallow... In order to maintain the safety of underground constructions that significantly involve geo-material uncertainties,this paper delivers a new computation framework for conducting reliability-based design(RBD)of shallow tunnel face stability,utilizing a simplified inverse first-order reliability method(FORM).The limit state functions defining tunnel face stability are established for both collapse and blow-out modes of the tunnel face failure,respectively,and the deterministic results of the tunnel face support pressure are obtained through three-dimensional finite element limit analysis(FELA).Because the inverse reliability method can directly capture the design support pressure according to prescribed target reliability index,the computational cost for probabilistic design of tunnel face stability is greatly reduced.By comparison with Monte Carlo simulation results,the accuracy and feasibility of the proposed method are verified.Further,this study presents a series of reliability-based design charts for vividly understanding the limit support pressure on tunnel face in both cohesionless(sandy)soil and cohesive soil stratums,and their optimal support pressure ranges are highlighted.The results show that in the case of sandy soil stratum,the blowout failure of tunnel face is extremely unlikely,whereas the collapse is the only possible failure mode.The parametric study of various geotechnical uncertainties also reveals that ignoring the potential correlation between soil shear strength parameters will lead to over-designed support pressure,and the coefficient of variation of internal friction angle has a greater influence on the tunnel face failure probability than that of the cohesion. 展开更多
关键词 Tunnel face stability Support pressure Finite element limit analysis Inverse reliability analysis Probabilistic design
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PREDICTION FOR FORMING LIMIT OF AL2024T3 SHEET BASED ON DAMAGE THEORY USING FINITE ELEMENT METHOD 被引量:1
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作者 Tang C.Y. Fan Jianping Tsui C.P. 《Acta Mechanica Solida Sinica》 SCIE EI 2006年第2期174-180,共7页
This paper presents the application of anisotropic damage theory to the study of forming limit diagram of A12024T3 aluminum alloy sheet. In the prediction of limiting strains of the aluminum sheet structure, a finite ... This paper presents the application of anisotropic damage theory to the study of forming limit diagram of A12024T3 aluminum alloy sheet. In the prediction of limiting strains of the aluminum sheet structure, a finite element cell model has been constructed. The cell model consists of two phases, the aluminum alloy matrix and the intermetallic cluster. The material behavior of the aluminum alloy matrix is described with a fully coupled elasto-plastic damage constitutive equation. The intermetallic cluster is assumed to be elastic and brittle. By varying the stretching ratio, the limiting strains of the sheet under biaxial stretching have been predicted by using the necking criterion proposed. The prediction is in good agreement with the experimental findings. Moreover, the finite element cell model can provide information for understanding the microscopic damage mechanism of the aluminum alloy. Over-estimation of the limit strains may result if the effect of material damage is ignored in the sheet metal forming study. 展开更多
关键词 forming limit diagram (FLD) anisotropic damage finite element method (FEM) limit strain localized necking elasto-plastic deformation
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Research on Seismic Behavior of Sloping Field Building Structure
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作者 MA Rong-hui FAN Qi WANG Bo-nan HUANG Rong-bin HE Heng-wei 《International Journal of Technology Management》 2015年第5期19-21,共3页
The paper set up 3D solid overall superstructure model of Foundation and Box foundation on Rock Slope Subgrade base using the ABAQUS, and the establish the infinite element boundary, superstructure displacement of Box... The paper set up 3D solid overall superstructure model of Foundation and Box foundation on Rock Slope Subgrade base using the ABAQUS, and the establish the infinite element boundary, superstructure displacement of Box foundation and foundation at Rock Slope Subgrade was studied by inputting different direction of earthquake response. The results show that, for the mountain frame structure, influence on the horizontal displacement of the vertical under the action of alone big earthquake, and vertical seismic action on horizontal displacement effect is smaller by mutual function of horizontal and vertical seismic, basically is same as response under the action of horizontal earthquake alone; for step shaped box foundation, the change trend of mutual function of horizontal and vertical earthquake was the complete opposite of the maximum story drift each layer under the one-way horizontal earthquake, which indicate the presence of vertical earthquake wave effect on the box foundation displacement cannot be ignored. 展开更多
关键词 I Rock slope base soil - structure interaction limited and infinite element coupling settlement analysis Seismic performanceanalysis
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EFFECT OF VELOCITY ON DUCTILITY UNDER HIGH VELOCITY FORMING
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作者 LI Zhong LI Chunfeng 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2007年第2期32-35,共4页
The ring expansion procedures over various forming velocities are calculated with ANSYS software in order to show the effect of forming velocity on ductility of rate insensitive materials. Ring expansion procedures ar... The ring expansion procedures over various forming velocities are calculated with ANSYS software in order to show the effect of forming velocity on ductility of rate insensitive materials. Ring expansion procedures are simplified to one-dimensional tension by constraining the radial deformation, with element birth and death method, fracture problem of circular ring are considered. The calculated results show that for insensitive materials of 1060 aluminum and 3A21 aluminum alloy, fracture strain increases corresponding to the increase of forming velocity. This trend agrees well with experimental results, and indicates inertia is the key factor to affect ductility; With element birth and death methods, fracture problems can be solved effectively. Experimental studies on formability of tubular workpieces are also conducted, experimental results show that the formability of 1060 aluminum and 3A21 aluminum alloy under electromagnetic forming is higher than that under quasistatic forming, according to the characteristics of electromagnetic forming, the forming limit diasrams of the two materials tube are also built respectively, this is very important to promote the development of electromagnetic forming and guide the engineering practices. 展开更多
关键词 Ductility Element birth and death method Formability Electromagnetic forming Forming limit diasram
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Undrained seismic bearing capacity of strip footing adjacent to a heterogeneous excavation
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作者 Ramin VALI Saeed KHOSRAVI Majid BEYGI 《Frontiers of Structural and Civil Engineering》 SCIE EI CSCD 2023年第4期566-583,共18页
The analysis of the bearing capacity of strip footings sited near an excavation is critical in geotechnics.In this study,the effects of the geometrical features of the excavation and the soil strength properties on th... The analysis of the bearing capacity of strip footings sited near an excavation is critical in geotechnics.In this study,the effects of the geometrical features of the excavation and the soil strength properties on the seismic bearing capacity of a strip footing resting on an excavation were evaluated using the lower and upper bounds of the finite element limit analysis method.The effects of the setback distance ratio(L/B),excavation height ratio(H/B),soil strength heterogeneity(kB/cu),and horizontal earthquake coefficient(kh)were analyzed.Design charts and tables were produced to clarify the relationship between the undrained seismic bearing capacity and the selected parameters. 展开更多
关键词 EXCAVATION finite element limit analysis heterogeneous soil strip footing undrained bearing capacity
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Undrained stability of pit-in-pit braced excavations under hydraulic uplift 被引量:1
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作者 Fengwen Lai Fuquan Chen +2 位作者 Songyu Liu Suraparb Keawsawasvong Jim Shiau 《Underground Space》 SCIE EI 2022年第6期1139-1155,共17页
Pit-in-pit(PIP)excavations in an aquifer–aquitard system likely undergo catastrophic failures under the hydraulic uplift,the associated undrained stability problem,however,has not been well analyzed in the past.To th... Pit-in-pit(PIP)excavations in an aquifer–aquitard system likely undergo catastrophic failures under the hydraulic uplift,the associated undrained stability problem,however,has not been well analyzed in the past.To this end,a hypothetical model of PIP braced excavation in typical soil layers of Shanghai,China is developed using the finite element limit analysis(FELA)tool.The FELA solutions of safety factors(FSs)against hydraulic uplift are verified with the results from the finite element analysis with strength reduction technique(SRFEA)and existing design approaches.Subsequently,FELA is employed to identify the triggering and failure mechanisms of PIP braced excavations subjected to hydraulic uplift.A series of parametric studies considering the various geometric configurations of the PIP excavation,undrained shear strengths of aquitard,and artesian pressures are carried out.The sensitivities of relevant design parameters are further assessed using a multivariate adaptive regression splines(MARS)model that is capable of accurately capturing the nonlinear relationships between a set of input variables and output variables in multi-dimensions.A MARS-based design equation used for predicting FS is finally presented using the artificial dataset from FELA for practical design uses. 展开更多
关键词 Pit-in-pit excavation Hydraulic uplift Undrained stability Finite element limit analysis Multivariate adaptive regression splines
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