检索结果-南通市图书馆

A unified state parameter model for sands with physical state changes

在线全文

学校读者我要写书评

暂无评论

A unified state parameter model for sands with physical stat...

Stress-dilatancy of Zipingpu gravel in triaxial compression tests

The 2nd International Conference on Environmental and Engineering Geophysics

作者： Shunhua Xu Guangli Xu Yao Cheng Engineering Faculty China University of Geosciences Wuhan 430074 China

＜正＞The behavior of sands varies with density and confining pressure. A new constitutive model was developed based on the state parameter, peak strength, the state dependent dilatancy equation and the yield surface with a hyperbolic relationship between the stress ratio and the plastic deviatoric strain. The model with seven parameters, which can be calculated from results of conventional triaxial test, can well represent the sand behavior with a unified way to take into account the density and confining pressure under monotonic loading. It is well kown that loose sands have large volumetric contraction under same confining pressures while dense sands have volumetric expansion, and sands under high confining pressures have contractive behavior while sands under low confining pressures have dilative behavior with same density. Sands will deflate before dilation with increasing the stress ratio no matter what triaxial compression test or triaxial extension test. This interfacial stress ratio with the physical state changes is steady and independent of density of sand. The modeling of the above deformation characteristics for sands agree reasonably well with triaxial drained test results.

关键词： dilatancy deflatancy state parameter peak stress ratio critical stress ratio

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2016年第2期59卷 214-224页

作者： LIU JingMao ZOU DeGao KONG XianJing LIU HuaBei state Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Institute of Earthquake Engineering School of Hydraulic Engineering Dalian University of Technology School of Civil Engineering and Mechanics Huazhong University of Science and Technology

Experimental investigations of the dilatancy and particle breakage of gravelly material from the Zipingpu concrete-faced rock- fill dam, which was subjected to high-intensity seismic load during the 2008 Wenchuan earthquake, were conducted through a series of large-scale drained triaxial compression tests. A hyperbolic relation between the input plastic work and the degree of particle breakage was found for Zipingpu gravel, independent of the initial void ratio and confining pressures. The stress-dilatancy for Zipingpu gravel was analyzed and compared with data from two rounded alluvial and three angular quar- ried gravelly and rockfill materials in the literature. A nearly linear relationship between the dilatancy Dp and the stress ratio η was found at medium-to-large stress ratios before the peak stress ratio. The slope of the stress-dilatancy line before peak had slight dependence on the void ratio and confining pressure of the gravel. After peak, the stress-dilatancy relation shifts down compared with that before peak for the gravel specimen. The phase-transformation stress ratio decreased with increased con- fining pressure, with the exception of sub-rounded gravel with little particle breakage. A nearly linear relationship was found between the phase-transformation stress ratio Mf and the state parameter ψ for the Zipingpu gravel, regardless of the void ratio and confining pressure of the specimens.

关键词： dilatancy gravel phase-transformation stress ratio triaxial compression state parameter particle breakage

Discrete element modelling of strength and critical state characteristics of granular materials under axial compression and axial extension stress path tests

在线全文

学校读者我要写书评

暂无评论

Particuology 2021年第3期19卷 152-162页

作者： Shiva Prashanth Kumar Kodicherla Guobin Gong Lei Fan Stephen Wilkinson Charles K.S.Moy Department of Civil Engineering Xi’an Jiaotong-Liverpool University(XJTLU)China Department of Civil Engineering University of WollongongDubai

The critical state soil mechanics(CSSM)framework has been widely used across a range of problems in geomechanics involving complex loading ***,the uniqueness of the critical state has been disputed for many years and it remains a controversial *** by previous investigations,a series of discrete element method(DEM)simulations were performed under both axial compression(AC)and axial extension(AE)stress *** samples were isotropically compressed at varying mean normal effective stresses(confining pressures)and sheared to a large axial strain of approximately 60%.It is found that there exist unique values of critical void ratios and stress ratios under critical state,which are independent of the samples’initial packings but dependent on stress *** the critical strength(stress ratio)for the AC stress path tests is higher than that for the AE stress *** critical state lines(CSLs)are found to path-dependent but unique for each stress path.A unique linear relationship between the critical coordination numbers and critical void ratios is identified under the AC and AE stress paths respectively,but such a relationship depends on the stress *** is also found that there exist unique values of microscopic parameters in terms of deviator fabric under critical state,which are independent of the samples’initial packings but dependent on stress *** these simulation results lead to the conclusion of non-uniqueness of CSLs from both macroscopic and microscopic viewpoints.

关键词： DEMClumped particles Critical state Densification index state parameter

Cyclic liquefaction screening of sand with non-plastic fines:Critical state approach

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geoscience Frontiers 2020年第2期11卷 429-438页

作者： Md.Mizanur Rahman TGSitharam Natural and Built Environments Research Centre(NBERC) School of Natural and Built EnvironmentsUniversity of South AustraliaMawson LakesSA 5095Australia Department of Civil Engineering Indian Institute of Science(IISc)BangaloreIndia

There have been significant advances in the application of critical state,CS,in liquefaction potential *** was done by comparing state parameter,j with estimated characteristic cyclic stress ratio,CSR due to an earthquake.A cyclic resistance ratio,CRR curve,which can be determined from cyclic liquefaction tests,separates historical liquefied and non-liquefied data points(j,CSR).On the other hand,the concepts of equivalent granular state parameter,j*,which was developed for sands with fines,can be used in lieu j to provide a unifying framework for characterizing the undrained response of sands with non/low plasticity fines,irrespective of fines content(fc).The present work combines these two propositions,and by merely substituting j*for j into the aforementioned CS approach to capture the influence of fc.A series of static and cyclic triaxial tests were conducted,separately and independently of the concept of j*,for sand with up to fc of 30%.The clean sand was collected from Sabarmati river belt at Ahmedabad city in India which was severely affected during the Bhuj earthquake,*** experimental data gave a single relation for CRR and j*which was then used to assess liquefaction potential for a SPT based case study,where fc varies along the *** prediction matched with the field observation.

关键词： Critical state state parameter Liquefaction Sands Fines Constitutive model

Bounding surface plasticity model for stress-strain and grain-crushing behaviors of rockfill materials

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2020年第2期11卷 495-510页

作者： Yang Xiao Zengchun Sun Armin WStuedlein Chenggui Wang Zhijun Wu Zhichao Zhang School of Civil Engineering Chongqing University83 Shabei StreetChongqing 400045China state Key Laboratory for GeoMechanics and Deep Underground Engineering China University of Mining&TechnologyXuzhou 221116China Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing UniversityChongqing 400045China state Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400030China School of Civil and Construction Engineering Oregon State Univ101 Kearney HallCorvallisOR97331USA School of Civil Engineering Wuhan UniversityWuhan 430072China

Crushing of grains can greatly influence the strength,dilatancy,and stress-strain relationship of rockfill *** critical state line(CSL)in the void ratio versus mean effective stress plane was extended to the breakage critical state plane(BCSP).A state void-ratio-pressure index that incorporated the effect of grain crushing was proposed according to the ***’s stress-dilatancy equation was modified by adding the breakage voidratio-pressure index,which was also incorporated into the formulations of the bounding stress ratio and plastic modulus.A BCSP-based bounding surface plasticity model was proposed to describe the state-dependent stressstrain behaviors and the evolution of grain crushing during shearing process of rockfill materials,and was shown to sufficiently capture the breakage phenomenon.

关键词： Constitutive model Grain crushing Critical state Dilatancy Strength state parameter