A non-orthogonal elastoplastic model for clay is proposed by combining the non-orthogonal plastic flow rule with the critical state concept, and the model framework is presented from the perspective of the magnitude and direction of the plastic strain increment. The magnitude is obtained based on the improved elliptical yield function and the plastic volumetric strain dependent hardening parameter. The direction is determined by ap-plying the non-orthogonal plastic flow rule with the Riemann-Liouville fractional derivative to the yield function without the necessity of additional plastic potential function. The presented approach gives rise to a simple model for soil with five parameters. All parameters have clear physical meaning and can be easily identified by triaxial tests. The model performance is shown by analyzing the evolution process of the yield surface, the hardening rule and the plastic flow direction. The capability of the proposed model to capture the mechanical behaviours of clay with different stiffness is also confirmed by predicting test results from the literature.
", "keywords": ["Civil and Environmental Engineering", "bepress|Engineering", "0211 other engineering and technologies", "Aerospace Engineering", "bepress|Engineering|Aerospace Engineering", "02 engineering and technology", "Geotechnical Engineering", "01 natural sciences", "engrXiv|Engineering|Aerospace Engineering", "Engineering", "engrXiv|Engineering", "bepress|Engineering|Civil and Environmental Engineering", "engrXiv|Engineering|Civil and Environmental Engineering|Geotechnical Engineering", "engrXiv|Engineering|Civil and Environmental Engineering", "bepress|Engineering|Civil and Environmental Engineering|Geotechnical Engineering", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://doi.org/10.1016/j.compgeo.2019.103200"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Computers%20and%20Geotechnics", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.compgeo.2019.103200", "name": "item", "description": "10.1016/j.compgeo.2019.103200", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.compgeo.2019.103200"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2019-12-01T00:00:00Z"}}, {"id": "10.1016/j.compgeo.2020.103486", "type": "Feature", "geometry": null, "properties": {"updated": "2026-04-03T16:16:25Z", "type": "Journal Article", "created": "2021-03-11", "title": "Extension of a basic hypoplastic model for overconsolidated clays", "description": "This paper presents a new rate-dependent hypoplastic constitutive model for overconsolidated clays. The model is developed based on a basic hypoplastic model proposed recently for sand. New density and stiffness factors are introduced to account for history dependence. The Matsuoka-Nakai failure surface is incorporated for the limit stress criterion. With six constitutive parameters, the model is capable of predicting the hardening/softening, shear dilation/contraction, and asymptotic state for overconsolidated clays. Comparison between numerical predictions and experimental results shows this model can properly describe the main features of both reconstituted and undisturbed clays with different overconsolidation ratios.
", "keywords": ["Civil and Environmental Engineering", "Engineering", "engrXiv|Engineering", "bepress|Engineering|Civil and Environmental Engineering", "bepress|Engineering", "engrXiv|Engineering|Civil and Environmental Engineering|Geotechnical Engineering", "engrXiv|Engineering|Civil and Environmental Engineering", "0211 other engineering and technologies", "02 engineering and technology", "Geotechnical Engineering", "bepress|Engineering|Civil and Environmental Engineering|Geotechnical Engineering", "01 natural sciences", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://doi.org/10.1016/j.compgeo.2020.103486"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Computers%20and%20Geotechnics", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.compgeo.2020.103486", "name": "item", "description": "10.1016/j.compgeo.2020.103486", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.compgeo.2020.103486"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2020-07-01T00:00:00Z"}}, {"id": "10.1029/2020gb006672", "type": "Feature", "geometry": null, "properties": {"updated": "2026-04-03T16:18:30Z", "type": "Journal Article", "created": "2020-09-02", "title": "Assessing the Potential for Mobilization of Old Soil Carbon After Permafrost Thaw: A Synthesis of 14C Measurements From the Northern Permafrost Region", "description": "AbstractThe magnitude of future emissions of greenhouse gases from the northern permafrost region depends crucially on the mineralization of soil organic carbon (SOC) that has accumulated over millennia in these perennially frozen soils. Many recent studies have used radiocarbon (14C) to quantify the release of this \uffe2\uff80\uff9cold\uffe2\uff80\uff9d SOC as CO2 or CH4 to the atmosphere or as dissolved and particulate organic carbon (DOC and POC) to surface waters. We compiled ~1,900 14C measurements from 51 sites in the northern permafrost region to assess the vulnerability of thawing SOC in tundra, forest, peatland, lake, and river ecosystems. We found that growing season soil 14C\uffe2\uff80\uff90CO2 emissions generally had a modern (post\uffe2\uff80\uff901950s) signature, but that well\uffe2\uff80\uff90drained, oxic soils had increased CO2 emissions derived from older sources following recent thaw. The age of CO2 and CH4 emitted from lakes depended primarily on the age and quantity of SOC in sediments and on the mode of emission, and indicated substantial losses of previously frozen SOC from actively expanding thermokarst lakes. Increased fluvial export of aged DOC and POC occurred from sites where permafrost thaw caused soil thermal erosion. There was limited evidence supporting release of previously frozen SOC as CO2, CH4, and DOC from thawing peatlands with anoxic soils. This synthesis thus suggests widespread but not universal release of permafrost SOC following thaw. We show that different definitions of \uffe2\uff80\uff9cold\uffe2\uff80\uff9d sources among studies hamper the comparison of vulnerability of permafrost SOC across ecosystems and disturbances. We also highlight opportunities for future 14C studies in the permafrost region.