GéotechniquePub Date : 2024-02-17DOI: 10.1680/jgeot.23.00068
Jiangtao Lei, Marcos Arroyo, M. Ciantia, Ningning Zhang
{"title":"A fracture-based discrete model for simulating creep in quartz sands","authors":"Jiangtao Lei, Marcos Arroyo, M. Ciantia, Ningning Zhang","doi":"10.1680/jgeot.23.00068","DOIUrl":"https://doi.org/10.1680/jgeot.23.00068","url":null,"abstract":"Creep of granular soils is frequently accompanied by grain breakage. Stress corrosion driven grain breakage offers a micromechanically based explanation for granular creep. This study incorporates that concept into a new model based on the discrete element method (DEM) to simulate creep in sands. The model aims for conceptual simplicity, computational efficiency and ease of calibration. To this end a new form of normalized Charles power law is incorporated into a DEM model for rough-crushable sands based on the particle splitting technique. The model is implemented using a controlled on-off computational strategy. The model is validated by simulating creep in quartz sands in oedometric and triaxial conditions. Model predictions are shown to compare favourably with experimental results in terms of creep strain, creep strain rates and particle breakage. The model proposed would facilitate the calibration of phenomenological continuum models, but may be also useful to directly investigate structural scale phenomena, such as pile ageing.","PeriodicalId":508398,"journal":{"name":"Géotechnique","volume":"60 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139960513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
GéotechniquePub Date : 2024-02-17DOI: 10.1680/jgeot.23.00134
Abigail Cartwright, Matthew Coop, Li Wei, Andy Fourie
{"title":"Cyclic liquefaction in transitional and non-transitional tailings","authors":"Abigail Cartwright, Matthew Coop, Li Wei, Andy Fourie","doi":"10.1680/jgeot.23.00134","DOIUrl":"https://doi.org/10.1680/jgeot.23.00134","url":null,"abstract":"Tailings have previously been identified as having the types of mixed mineralogies and gradings that can make them susceptible to having non-unique critical states and normally compressed states in laboratory element tests. This paper addresses how this mode of behaviour would affect their resistance to undrained cyclic loading, contrasting two triaxial studies, one on a tailings that has a conventional behaviour and one transitional. To demonstrate the influence of transitional behaviour it was necessary to create samples with as wide a range of initial specific volumes as possible, while trying keep the sample preparation methods the same for loose and dense samples. It was also necessary to examine the cyclic data in non-conventional ways, notably in the volumetric plane to highlight better the effects of initial sample specific volume. It is shown that, as previously determined for monotonic loading, the initial density has much less influence on the cyclic behaviour of a soil with transitional behaviour than it would for a conventional soil, and it is instead the stress history that is very much more important. Samples following their respective normal compression lines exhibit similar behaviour but overconsolidation significantly enhances resistance and a sample that arrives at a given state by the undrained reduction of p’ due to cycling also has a much higher resistance.","PeriodicalId":508398,"journal":{"name":"Géotechnique","volume":"63 23","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139960048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
GéotechniquePub Date : 2024-01-13DOI: 10.1680/jgeot.23.00195
Zheng Zhou, Ali Akbar Karimzadeh, Anthony Kwan Leung, Sum Yin Fok
{"title":"Hysteretic water retention behaviour of unsaturated hydrophobised soils","authors":"Zheng Zhou, Ali Akbar Karimzadeh, Anthony Kwan Leung, Sum Yin Fok","doi":"10.1680/jgeot.23.00195","DOIUrl":"https://doi.org/10.1680/jgeot.23.00195","url":null,"abstract":"Hydrophobised soils found in the superficial region of earthen infrastructure can affect the hydrological processes of these structures. Hysteretic water retention curve (WRC), which governs these processes, for hydrophobised soils has rarely been reported. Existing apparatus was unable to measure the WRC of unsaturated soil as they cannot control the condition of pore water pressure (uw) in excess of pore air pressure (ua) when the contact angle is larger than 90°. This study created a new apparatus, which sandwiches a soil sample by a pair of high water-entry value (WEV) membrane and a high air-entry value (AEV) ceramic disk, to control the uw < ua and uw > ua conditions. Contact angle hysteresis and menisci evolution in the test materials during wet–dry cycles were measured to interpret the WRC. Results show that the WEV of soil was increased with decreasing chemical heterogeneity and particles size. When drying the hydrophobised soils, they could retain water before reaching a certain negative uw. The WEV identified from the second wetting cycle was lower than that from the first cycle, whereas the AEV remained largely unchanged. The WEV and AEV decreased when the particle size of the hydrophobised materials was increased, resulting in a smaller hysteresis size.","PeriodicalId":508398,"journal":{"name":"Géotechnique","volume":"33 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139531744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
GéotechniquePub Date : 2013-04-24DOI: 10.1680/geot.12.p.154
J. R. Standing, Dimitrios Selemetas
{"title":"Greenfield ground response to EPBM tunnelling in London Clay","authors":"J. R. Standing, Dimitrios Selemetas","doi":"10.1680/geot.12.p.154","DOIUrl":"https://doi.org/10.1680/geot.12.p.154","url":null,"abstract":"Earth-pressure-balance machines (EPBMs) are frequently used in preference to more conventional non-pressurised tunnel-boring machines (TBMs) to minimise ground movements in the urban environment. The greenfield ground response to EPBM tunnelling in London Clay from a field monitoring research study is presented and discussed. Vertical and horizontal displacements and pore pressure changes were measured with an extensive array of surface and subsurface instruments. Surface settlement troughs observed above the tunnels were small (w max < 10 mm) and can be modelled using the commonly adopted inverse Gaussian curve, but a complex kinematic mechanism took place within the subsurface ground. In the near vicinity of the pressurised closed-face tunnel-boring machine an ‘expanding' displacement field was observed, in contrast to the ‘contracting' field often observed and associated with open-face tunnelling. This expanding response is dependent on TBM variables, such as face pressure, and should be contemplated when predicting ground movements and assessing subsurface structures such as piles and existing tunnels.","PeriodicalId":508398,"journal":{"name":"Géotechnique","volume":"63 12","pages":"989-1007"},"PeriodicalIF":0.0,"publicationDate":"2013-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147889975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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