Géotechnique最新文献_第3页

Progressive internal erosion during triaxial shearing: an X-ray micro-computed tomography study 三轴剪切过程中的渐进式内侵蚀：X 射线微型计算机断层扫描研究

Géotechnique Pub Date : 2024-02-27 DOI: 10.1680/jgeot.23.00107

Zhangqi Xia, Jianfeng Wang, Zhiren Zhu, Wei Hu, Saoirse Tracy, Budi Zhao

{"title":"Progressive internal erosion during triaxial shearing: an X-ray micro-computed tomography study","authors":"Zhangqi Xia, Jianfeng Wang, Zhiren Zhu, Wei Hu, Saoirse Tracy, Budi Zhao","doi":"10.1680/jgeot.23.00107","DOIUrl":"https://doi.org/10.1680/jgeot.23.00107","url":null,"abstract":"Fines removal during internal erosion results in permeability increase and strength reduction of granular soils. This study examines internal erosion during shearing of granular soils under triaxial loading conditions using a specially designed apparatus and X-ray CT scans. Two gap-graded soil samples with different fines content are tested and scanned multiple times to characterize sample- and pore-scale volume change and fines content using image processing techniques. Results show that internal erosion increases gradually with axial strain and has a complex impact on permeability increase due to the spatial variation of fines content. Triaxial shearing induces both pore contraction and dilation, destabilises the clogging of fine particles, and promotes internal erosion. Also, the erosion of force-supporting fine particles at a high fines content facilitates pore contraction. The progressive internal erosion due to mechanical disturbance leads to the formation of a flow channel from the upstream loading platen throughout the sample, resulting in a dramatical increase in permeability. Overall, this study provides novel insights into the interplay between the hydro-mechanical processes during shearing under constant seepage.","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140322244","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}

引用次数: 0

An experimental study on factors affecting the ageing of shaft friction on steel displacement piles in sand 关于影响砂中钢质位移桩轴摩擦老化因素的实验研究

Géotechnique Pub Date : 2024-02-27 DOI: 10.1680/jgeot.23.00047

Eduardo M. Bittar, Barry M. Lehane

{"title":"An experimental study on factors affecting the ageing of shaft friction on steel displacement piles in sand","authors":"Eduardo M. Bittar, Barry M. Lehane","doi":"10.1680/jgeot.23.00047","DOIUrl":"https://doi.org/10.1680/jgeot.23.00047","url":null,"abstract":"Ageing of shaft friction is now an accepted characteristic of displacement piles in sand. However, there is little guidance available on how the associated gains in pile capacity can be incorporated in design. This paper provides an overview of findings from a number of previous high-quality investigations before presenting results from a recent three-year pile testing campaign in the field that targeted aspects of pile ageing to improve understanding of the ageing mechanism. The field testing involved 52 tension tests on pipe piles and specifically examined the influence of installation method (driving, vibration, vibration + driving), pile diameter, steel type and loading history (static and cyclic). These results, taken together with other experimental investigations, show that the development of a welded crust on the pile shaft is a necessary part of the ageing process for steel piles and that the increase with time in the level of constrained dilation under shear on this crust is a primary contributor to ageing of shaft friction. Creep within the sand mass following the disturbance induced by installation can explain the increase in the level of this constraint while stress redistribution and breakdown of arching may also contribute to the phenomenon. Ageing leads to the inference of long-term aged shaft frictions (in tension) of 500mm and 2m diameter pipe piles that are respectively at least 50% and 30% higher than given by the design method in ISO-19901-4 (2024). Additional observations from the field tests relating to the effect of the installation method, steel type and load history on the ageing of shaft friction are made that can assist designers.","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140202313","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}

引用次数: 0

Causes of the high friction angle of diatomaceous soil: microscale and nanoscale insights 硅藻土高摩擦角的成因：微尺度和纳米尺度的启示

Géotechnique Pub Date : 2024-02-08 DOI: 10.1680/jgeot.23.00230

Xianwei Zhang, Xinyu Liu, Gang Wang, Yiqing Xu, Haodong Gao

{"title":"Causes of the high friction angle of diatomaceous soil: microscale and nanoscale insights","authors":"Xianwei Zhang, Xinyu Liu, Gang Wang, Yiqing Xu, Haodong Gao","doi":"10.1680/jgeot.23.00230","DOIUrl":"https://doi.org/10.1680/jgeot.23.00230","url":null,"abstract":"Diatomaceous soil has geotechnical properties that differ fundamentally from those of common non-diatomaceous soils due to the presence of diatom microfossils with biological origins. Despite its dominant fines content, diatomaceous soil usually has high frictional shear resistance (approaching that of sand). Currently, the exact role of diatoms in controlling soil strength and underlying mechanisms remain obscure. Here, the frictional strength of diatomaceous soil is evaluated via angle-of-repose and direct simple shear tests on diatom–kaolin mixtures with differing diatom content. The microscale and nanoscale structures are characterised in detail via scanning-electron and atomic-force microscopy to establish how soil structure evolutes with diatom content and shear. For the studied diatom–kaolin mixtures, the angle of repose and internal frictional angle are high and increase with diatom content, especially when diatom content exceeds 20%. Diatom controls the frictional strength through its intricate morphology (cylindrical, saucer and disc shapes), very rough surface (hundreds of times rougher than flaky minerals), and stiff frustules with high Young's modulus. These features increase the particle coordination number and produce interparticle interlockings, both of which prevent particle rearrangement during shear and improve the frictional strength. This paper provides new insights into the multiscale structure of diatoms and improves the understanding of the shear strength of diatomaceous soils.","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139851672","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}

引用次数: 0

A micromechanical model for estimating the shear modulus and damping ratio of loose sands under low stresses. Application to a Mars regolith simulant 用于估算低应力下松散砂的剪切模量和阻尼比的微机械模型。应用于火星碎屑模拟物

Géotechnique Pub Date : 2024-02-08 DOI: 10.1680/jgeot.23.00244

B. Caicedo, M. J. Chaparro, J. P. Castillo Betancourt, M. Cabrera, P. Delage, P. Lognonné, B. Banerdt

{"title":"A micromechanical model for estimating the shear modulus and damping ratio of loose sands under low stresses. Application to a Mars regolith simulant","authors":"B. Caicedo, M. J. Chaparro, J. P. Castillo Betancourt, M. Cabrera, P. Delage, P. Lognonné, B. Banerdt","doi":"10.1680/jgeot.23.00244","DOIUrl":"https://doi.org/10.1680/jgeot.23.00244","url":null,"abstract":"The dynamic properties of loose sands under low stresses have been poorly investigated because of the higher order of magnitude of stress levels in terrestrial geotechnical structures. However, low densities and low stresses prevail in the sandy surface deposits of some other rocky planets, making low stress conditions relevant for extra-terrestrial soil mechanics. This is the case of Mars, on the surface of which a seismometer has been placed during the InSight mission. In this context, a dynamic shear rheometer was used to measure the shear modulus and damping ratio of a Martian regolith simulant under very low stresses to improve the interpretation of the InSight dataset on surface materials. This paper also revisits the grain contact stiffness and the overall modulus of a random packing of identical spheres, based on the Hertz-Mindlin contact theory. A micromechanical model accounting for the effects of both grain roughness and slipping in the soil degradation curve is proposed. The results of the model show a good agreement with experimental data, capturing the non-linear transition from low to high-shear strains. The model hence provides a new framework for a better understanding of the behaviour of granular materials in low gravity (extra-terrestrial) conditions.","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139852612","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}

引用次数: 0

Causes of the high friction angle of diatomaceous soil: microscale and nanoscale insights 硅藻土高摩擦角的成因：微尺度和纳米尺度的启示

Géotechnique Pub Date : 2024-02-08 DOI: 10.1680/jgeot.23.00230

Xianwei Zhang, Xinyu Liu, Gang Wang, Yiqing Xu, Haodong Gao

{"title":"Causes of the high friction angle of diatomaceous soil: microscale and nanoscale insights","authors":"Xianwei Zhang, Xinyu Liu, Gang Wang, Yiqing Xu, Haodong Gao","doi":"10.1680/jgeot.23.00230","DOIUrl":"https://doi.org/10.1680/jgeot.23.00230","url":null,"abstract":"Diatomaceous soil has geotechnical properties that differ fundamentally from those of common non-diatomaceous soils due to the presence of diatom microfossils with biological origins. Despite its dominant fines content, diatomaceous soil usually has high frictional shear resistance (approaching that of sand). Currently, the exact role of diatoms in controlling soil strength and underlying mechanisms remain obscure. Here, the frictional strength of diatomaceous soil is evaluated via angle-of-repose and direct simple shear tests on diatom–kaolin mixtures with differing diatom content. The microscale and nanoscale structures are characterised in detail via scanning-electron and atomic-force microscopy to establish how soil structure evolutes with diatom content and shear. For the studied diatom–kaolin mixtures, the angle of repose and internal frictional angle are high and increase with diatom content, especially when diatom content exceeds 20%. Diatom controls the frictional strength through its intricate morphology (cylindrical, saucer and disc shapes), very rough surface (hundreds of times rougher than flaky minerals), and stiff frustules with high Young's modulus. These features increase the particle coordination number and produce interparticle interlockings, both of which prevent particle rearrangement during shear and improve the frictional strength. This paper provides new insights into the multiscale structure of diatoms and improves the understanding of the shear strength of diatomaceous soils.","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139791623","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}

引用次数: 0

A micromechanical model for estimating the shear modulus and damping ratio of loose sands under low stresses. Application to a Mars regolith simulant 用于估算低应力下松散砂的剪切模量和阻尼比的微机械模型。应用于火星碎屑模拟物

Géotechnique Pub Date : 2024-02-08 DOI: 10.1680/jgeot.23.00244

B. Caicedo, M. J. Chaparro, J. P. Castillo Betancourt, M. Cabrera, P. Delage, P. Lognonné, B. Banerdt

{"title":"A micromechanical model for estimating the shear modulus and damping ratio of loose sands under low stresses. Application to a Mars regolith simulant","authors":"B. Caicedo, M. J. Chaparro, J. P. Castillo Betancourt, M. Cabrera, P. Delage, P. Lognonné, B. Banerdt","doi":"10.1680/jgeot.23.00244","DOIUrl":"https://doi.org/10.1680/jgeot.23.00244","url":null,"abstract":"The dynamic properties of loose sands under low stresses have been poorly investigated because of the higher order of magnitude of stress levels in terrestrial geotechnical structures. However, low densities and low stresses prevail in the sandy surface deposits of some other rocky planets, making low stress conditions relevant for extra-terrestrial soil mechanics. This is the case of Mars, on the surface of which a seismometer has been placed during the InSight mission. In this context, a dynamic shear rheometer was used to measure the shear modulus and damping ratio of a Martian regolith simulant under very low stresses to improve the interpretation of the InSight dataset on surface materials. This paper also revisits the grain contact stiffness and the overall modulus of a random packing of identical spheres, based on the Hertz-Mindlin contact theory. A micromechanical model accounting for the effects of both grain roughness and slipping in the soil degradation curve is proposed. The results of the model show a good agreement with experimental data, capturing the non-linear transition from low to high-shear strains. The model hence provides a new framework for a better understanding of the behaviour of granular materials in low gravity (extra-terrestrial) conditions.","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139792606","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}

引用次数: 0

A comprehensive numerical investigation of multi-scale particle shape effects on small strain stiffness of sands 砂的小应变刚度的多尺度颗粒形状效应的综合数值研究

Géotechnique Pub Date : 2024-02-01 DOI: 10.1680/jgeot.23.00118

Jia-Yan Nie, Yifei Cui, Guodong Wang, Rui Wang, Ningning Zhang, Lei Zhang, Zhijun Wu

{"title":"A comprehensive numerical investigation of multi-scale particle shape effects on small strain stiffness of sands","authors":"Jia-Yan Nie, Yifei Cui, Guodong Wang, Rui Wang, Ningning Zhang, Lei Zhang, Zhijun Wu","doi":"10.1680/jgeot.23.00118","DOIUrl":"https://doi.org/10.1680/jgeot.23.00118","url":null,"abstract":"The effects of multi-scale particle shape characteristics on small strain stiffness of granular soils remain controversial. This study revisits this topic using well calibrated three-dimensional discrete element simulations incorporating into particle roughness-embedded contact model and realistic shape particles. Based on the numerical simulation results, the multi-scale particle shape effects on the small strain stiffness of sands and magnitude of Hardin's equation parameters are systematically investigated, and the underlying micro-mechanisms are also thoroughly explored. Results indicate that the small strain stiffness increases with the increase of particle overall irregularity due to the increased mechanical coordination number, while decreases with the increase of particle surface roughness because of the decreased contact normal stiffness. And the constant term and void ratio term parameters of Hardin's equation increases and decreases linearly, respectively, with the particle overall regularity, while reduces and grows with the particle surface roughness, respectively. Furthermore, the stress exponent is almost unchanged with the particle overall regularity, while increases with the particle surface roughness which determines the relative proportions of contacts under asperity dominated, transitional and Hertzian stages. The study helps to advance our cross-scale understanding of multi-scale particle shape information in relation to small strain stiffness of sands.","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139829022","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}

引用次数: 4

A comprehensive numerical investigation of multi-scale particle shape effects on small strain stiffness of sands 砂的小应变刚度的多尺度颗粒形状效应的综合数值研究

Géotechnique Pub Date : 2024-02-01 DOI: 10.1680/jgeot.23.00118

Jia-Yan Nie, Yifei Cui, Guodong Wang, Rui Wang, Ningning Zhang, Lei Zhang, Zhijun Wu

{"title":"A comprehensive numerical investigation of multi-scale particle shape effects on small strain stiffness of sands","authors":"Jia-Yan Nie, Yifei Cui, Guodong Wang, Rui Wang, Ningning Zhang, Lei Zhang, Zhijun Wu","doi":"10.1680/jgeot.23.00118","DOIUrl":"https://doi.org/10.1680/jgeot.23.00118","url":null,"abstract":"The effects of multi-scale particle shape characteristics on small strain stiffness of granular soils remain controversial. This study revisits this topic using well calibrated three-dimensional discrete element simulations incorporating into particle roughness-embedded contact model and realistic shape particles. Based on the numerical simulation results, the multi-scale particle shape effects on the small strain stiffness of sands and magnitude of Hardin's equation parameters are systematically investigated, and the underlying micro-mechanisms are also thoroughly explored. Results indicate that the small strain stiffness increases with the increase of particle overall irregularity due to the increased mechanical coordination number, while decreases with the increase of particle surface roughness because of the decreased contact normal stiffness. And the constant term and void ratio term parameters of Hardin's equation increases and decreases linearly, respectively, with the particle overall regularity, while reduces and grows with the particle surface roughness, respectively. Furthermore, the stress exponent is almost unchanged with the particle overall regularity, while increases with the particle surface roughness which determines the relative proportions of contacts under asperity dominated, transitional and Hertzian stages. The study helps to advance our cross-scale understanding of multi-scale particle shape information in relation to small strain stiffness of sands.","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139888969","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}

引用次数: 4

Introduction for the 61st Rankine Lecture 第 61 届兰金讲座简介

Géotechnique Pub Date : 2024-01-19 DOI: 10.1680/jgeot.23.00600

Mark Randolph

引用次数: 0

Coupled hydromechanical modelling of cone penetration in layered liquefiable soils 层状可液化土壤中锥入度的耦合水力学模型

Géotechnique Pub Date : 2024-01-09 DOI: 10.1680/jgeot.23.00164

Katia Boschi, Marcos Arroyo Alvarez de Toledo, L. Vila, Josep Maria Carbonell, A. Solé

引用次数: 0