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Journal of Central South University 2017年第12期24卷 2940-2950页

作者： YANG Zi-han ZHANG Rui XU Jing-shu YANG Xiao-li School of Civil Engineering Central South University Changsha 410075 China

The geological hazards, such as water inrush and mud outburst, are easily induced by the high water pressure caverns ahead of a karst tunnel face. Therefore, it is a pivotal issue to determine the reserved thickness of rock plug during the construction of tunnels. The limit analysis principle is employed to analyze the safe thickness from the point of energy dissipation, and the nonlinear and non-associated characteristics of geotechnical materials are both considered. On the basis of a plane failure pattern of rock plug, the expressions of detaching curve and rock plug thickness are derived. The effect of each parameter on the safe thickness of rock plug is discussed in detail, which interprets the corresponding failure scope of rock plug. The obtained results indicate that the thickness of rock plug is highly influenced by the nonlinear dilatancy coefficient and the nonlinear coefficient. The proposed method is validated by a comparison of the calculated results with those of the engineering project of the "526 karst cavern" of Yunwushan tunnel. This proposed method can provide reference basis for the design and excavation of karst tunnels in the future.

关键词： karst tunnel water inrush safe thickness of rock plug upper bound theorem nonlinear failure criterion non-associated flow rule

Pseudo-dynamic analysis of seismic stability of reinforced slopes considering non-associated flow rule

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Journal of Central South University 2011年第6期18卷 2091-2099页

作者： A.Eskandarinejad A.H.Shafiee Civil Engineering Department University of Hormozgan Civil Engineering Department Shiraz University

The required reinforcement force to prevent instability and the yield acceleration of reinforced slopes are computed under seismic loading by applying the kinematic approach of limit analysis in conjunction with the pseudo-dynamic method for a wide range of soil cohesion, friction angle, dilation angle and horizontal and vertical seismic coefficients. Each parameter threatening the stability of the slope enhances the magnitude of the required reinforcement force and vice versa. Moreover, the yield acceleration increases with the increase in soil shear strength parameters but decreases with the increase in the slope angle. The comparison of the present work with some of the available solutions in the literatures shows a reasonable agreement.

关键词： reinforced slope seismic stability pseudo-dynamic approach non-associated flow rule cohesive slope

The study of slip line field and upper bound method based on associated flow and non-associated flow rules

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Engineering Sciences 2010年第3期8卷 21-40页

作者： Zheng Yingren Deng Chujian Wang Jinglin Logistical Engineering University Chongqing 400041 China No. 6 Air Defense Engineering Department of PLA Air Force Hengyang Hunan 421001 China

At present, associated flow rule of traditional plastic theory is adopted in the slip line field theory and upper bound method of geotechnical materials. So the stress characteristic line conforms to the velocity line. It is proved that geotechnical materials do not abide by the associated flow rule. It is impossible for the stress characteristic line to conform to the velocity line. Generalized plastic mechanics theoretically proved that plastic potential surface intersects the Mohr-Coulomb yield surface with an angle, so that the velocity line must be studied by non-associated flow rule. According to limit analysis theory, the theory of slip line field is put forward in this paper, and then the ultimate beating capacity of strip footing is obtained based on the associated flow rule and the non-associated flow nile individually. These two results are identical since the ultimate bearing capacity is independent of flow role. On the contrary, the velocity fields of associated and non-associated flow rules are different which shows the velocity field based on the associat- ed flow rule is incorrect.

关键词： slip line field upper bound method associated flow rule non-associated flow rule generalized plastic theory

Elastoplastic homogenization of particulate composites complying with the Mohr–Coulomb criterion and undergoing isotropic loading

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Acta Mechanica Sinica 2015年第3期31卷 392-405页

作者： D.Yang Q.C.He School of Mechanical Engineering Southwest Jiaotong University Université Paris-Est Laboratoire Modélisation et Simulation Multi Echelle UMR 8208 CNRS

This work aims at determining the overall response of a two-phase elastoplastic composite to isotropic loading. The composite under investigation consists of elastic particles embedded in an elastic perfectly plastic matrix governed by the Mohr-Coulomb yield criterion and a non-associated plastic flow rule. The composite sphere assemblage model is adopted, and closed-form estimates are derived for the effective elastoplastic properties of the composite either under tensile or compressive isotropic loading. In the case when elastic particles reduce to voids, the composite in question degenerates into a porous elastoplastic material. The results obtained in the present work are of interest, in particular, for soil mechanics.

关键词： Composite Porous medium. Elastoplasticity Mohr-Coulomb yield criterion non-associated flow rule Homogenization

Characterization of the asymmetric evolving yield and flow of 6016-T4 aluminum alloy and DP490 steel

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Journal of Materials Science & Technology 2023年第2期133卷 209-229页

作者： Kai Du Shaohui Huang Yong Hou Haibo Wang Yinxiao Wang Wentao Zheng Xiaoguang Yuan School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China Department of Technical Planning Press Shop BMW Brilliance Automotive Ltd.Shenyang 100044China Department of Materials Science and Engineering&RIAM Seoul National UniversitySeoul 08826Republic of Korea School of Mechanical and Materials Engineering North China University of TechnologyBeijing 100144China

6016-T4 aluminum alloy and DP490 steel were systematically tested under 24 proportional loading paths,including uniaxial tensile tests with a 15°increment,uniaxial compressive and simple shear tests with a 45°increment,and biaxial tensile tests using cruciform *** specimens in the rolling/transverse and 45°/135°sampling directions were tested with seven and four different stress ra-tios,*** normal and diagonal planes plastic work contours and the yield stresses under uniaxial tension and compression were measured to investigate the anisotropic ***,the normal and diagonal planes directions of plastic strain rate and the rα-values under uniaxial tension and compression were characterized to confirm the plastic *** existing asymmetric yield crite-ria under the associated and non-associated flow rules were comprehensively evaluated to describe the asymmetric plastic anisotropy of 6016-T4 aluminum alloy and DP490 *** results suggest that in the investigated yield criteria,the non-associated models can predict the tension and compression asym-metry of materials more accurately than the associated models,and the function of stress triaxiality can more effectively describe the asymmetric yield behavior than the first stress *** addition,the pure shear stress states are helpful in assessing the validity and applicability of advanced asymmetric yield stress functions,and the inspection of diagonal plane plastic work contours containing more pure shear stress states should prioritized over that of normal plane plastic work *** evaluation of plastic potential functions should not only consider the prediction accuracy of the normal plane di-rections of plastic strain rate,but also further check the diagonal plane directions of plastic strain *** mechanical properties as a function of equivalent plastic strain to calibrate parameters of the yield criterion allows the continuous capture of anisot

关键词： Proportional loading paths Diagonal plane Asymmetric yield criterion non-associated flow rule Anisotropic hardening Sheet metal forming

non‑associated and non‑quadratic Characteristics in Plastic Anisotropy of Automotive Lightweight Sheet Metals

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Automotive Innovation 2023年第3期6卷 364-378页

作者： Yong Hou Junying Min Myoung‑Gyu Lee Department of Materials Science and Engineering and RIAM Seoul National UniversitySeoul 08826South Korea School of Mechanical Engineering Tongji UniversityShanghai 201804China

Lightweight sheet metals are highly desirable for automotive applications due to their exceptional strength-to-density *** accurate description of the pronounced plastic anisotropy exhibited by these materials in finite element analysis requires advanced plasticity *** recent years,significant efforts have been devoted to developing plasticity models and numeri-cal analysis methods based on the non-associated flow rule(non-AFR).In this work,a newly proposed coupled quadratic and non-quadratic model under non-AFR is utilized to comprehensively investigate the non-associated and non-quadratic characteristics during the yielding of three lightweight sheet metals,i.e.,dual-phase steel DP980,TRIP-assisted steel QP980,and aluminum alloy *** materials are subjected to various proportional loading paths,including uniaxial tensile tests with a 15°increment,uniaxial compressive tests with a 45°increment,in-plane torsion tests,and biaxial tensile tests using laser-deposited arm-strengthened cruciform *** show that the non-AFR approach provides an effective means for accurately modeling the yield behavior,including yield stresses and the direction of plastic strain rates,simultaneously,utilizing two separate functions and a simple calibration *** introduction of the non-quadratic plastic potential reduces the average errors in angle when predicting plastic strain directions by the quadratic plastic potential ***,for DP980,the average error is reduced from 3.1°to 0.9°,for QP980 it is reduced from 6.1°to 3.9°,and for AA5754-O it is reduced from 7.0°to 0.2°.This highlights the importance of considering the non-quadratic characteristic in plasticity modeling,especially for aluminum alloys such as AA5754-O.

关键词： Yield behavior non-associated flow rule non-quadratic Lightweight sheet metal

Critical state model for structured soil

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第3期12卷 630-641页

作者： Cristhian Mendoza Marcio Muniz de Farias Department of Civil Engineering Universidad Nacional de Colombia Sede ManizalesManizalesColombia Department of Civil and Environmental Engineering University of BrasiliaBrasiliaDFBrazil

Structure is an evident determinant for macroscopic behaviors of ***,this is not taken into account in most constitutive models,as structure is a rather complex issue in *** this,it is important to develop and implement simple models that can reflect this important aspect of soil *** paper tried to model structured soils based on well-established concepts,such as critical state and *** state is the core of the classic Cam Clay *** sub-loading concept implies adoption of an inner(sub-loading)yield surface,according to specific hardening rules for some internal strain-like state *** and co-workers proposed such internal variables for controlling density(p)and structure(ω),using a modified stress space,called ***,similar variables are used in the context of the better-known invariants(p and q)of the Cam Clay *** change requires explicit adoption of a non-associated flow rule for the sub-loading *** is accomplished by modifying the dilatancy ratio of the Cam Clay model,as a function of the new internal *** modifications are described and implemented under three-dimensional(3D)*** model is then applied to simulating laboratory tests under different stress paths and the results are compared to experiments reported for different types of structured *** good agreements show the capacity and potential of the proposed model.

关键词： Elastoplasticity Cam clay with sub-loading Structured soil Tropical soil non-associated flow rule

Improved slope safety analysis by new Druker-Prager type criterion

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Journal of Central South University 2012年第4期19卷 1132-1137页

作者：朱俊高彭凯 J.F.Shao 刘汉龙 Key Laboratory of Geo-mechanics and Embankment Engineering of Ministry of Education Hohai University Geotechnical Research Institute Hohai University Laboratoire de Mécanique de Lille UMR CNRS 8107Equipe Mécanique des Géomatériaux CohérentsPolytech'LilleCité Scientifique59655 Villeneuve d'AscqFrance

Based on Mohr-Coulomb （M-C） criterion, the parameters of Druker-Prager （D-P） criterion for geomaterial were determined under non-associated flow rule, and thus a new D-P type criterion was presented. Two assumptions were employed during the derivation： 1） principal strains by M-C model and D-P model are equal, and 2） the material is under plane strain condition. Based on the analysis of the surface on rt plane, it is found that the proposed D-P type criterion is better than the D-P criterion with M-C circumscribed circle or M-C inscribed circle, and is applicable for stress Lode angle less than zero. By comparing the predicted results with the test data of sand under plane strain condition and other D-P criteria, the proposed criterion is verified and agrees well with the test data, which is further proved to be better than other D--P type criteria in certain range of Lode angle. The criterion was compiled into a finite difference package FLAC3D by user-subroutine, and was used to analyze the stability of a slope by strength reduction method. The predicted slope safety factor from the proposed criterion agrees well with that by Spencer method, and it is more accurate than that from classic D-P criteria.

关键词： yield criterion non-associated flow rule dilatancy angle plastic potential function