Data gathered from 65 922 articles published in 30 geotechnical engineering journals between 1998 and 2022 were used to build a topic model and study the evolution of research output in the field. Over this period, the number of journal publications has grown exponentially with the number of articles published per year doubling every 6·3 years. The average citations per article (32·7) are skewed by highly cited articles, which make up 7·8% of the articles but account for 34·5 of the total number of citations. The articles’ country of origin has become increasingly centralised, with nearly half the articles published between 2018 and 2022 coming from China (39%) and the United States (10%). The topic distribution in the field has become highly specialised, with emerging topics being fuelled by: (a) new technologies and methods (i.e. data science and sensing techniques – the fastest-growing topics), and (b) rising applications seemingly related to mitigation (e.g. offshore and energy geotechnics) and adaptation (e.g. geohazards, mass movements) to climate change. As a consequence, traditional topics (e.g. soil and rock mechanics) have reduced their share in the field, but still remain among the most cited topics in geotechnical engineering.
{"title":"Growth, trends and prevalent topics in geotechnical engineering (1998–2022) using topic modelling","authors":"F. Patino-Ramirez, C. O'Sullivan","doi":"10.1680/jgele.23.00097","DOIUrl":"https://doi.org/10.1680/jgele.23.00097","url":null,"abstract":"Data gathered from 65 922 articles published in 30 geotechnical engineering journals between 1998 and 2022 were used to build a topic model and study the evolution of research output in the field. Over this period, the number of journal publications has grown exponentially with the number of articles published per year doubling every 6·3 years. The average citations per article (32·7) are skewed by highly cited articles, which make up 7·8% of the articles but account for 34·5 of the total number of citations. The articles’ country of origin has become increasingly centralised, with nearly half the articles published between 2018 and 2022 coming from China (39%) and the United States (10%). The topic distribution in the field has become highly specialised, with emerging topics being fuelled by: (<i>a</i>) new technologies and methods (i.e. data science and sensing techniques – the fastest-growing topics), and (<i>b</i>) rising applications seemingly related to mitigation (e.g. offshore and energy geotechnics) and adaptation (e.g. geohazards, mass movements) to climate change. As a consequence, traditional topics (e.g. soil and rock mechanics) have reduced their share in the field, but still remain among the most cited topics in geotechnical engineering.","PeriodicalId":501470,"journal":{"name":"Géotechnique Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140302723","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}
Cracking resulting from drying (constrained dehydration) poses a significant challenge in geomaterials, impacting their mechanical performance. To address this problem, extensive efforts have been made to prevent or mitigate the occurrence of cracks, with recent attention focused on the utilisation of biopolymers. This letter investigates the influence of varying concentrations of the xanthan biopolymer on the mechanical response of granular materials, examining both macro and micro scales. The strength changes of the soil were evaluated through desiccation experiments, analysing the appearance and progression of failure on the macro scale. The findings of this study demonstrate that failure (cracking) progression is mitigated and eventually eliminated by increasing the concentration of the additive xanthan. Additionally, capillary experiments were conducted to assess the changes in attraction and the development of capillary bridges on the micro-scale. They indicate that the formation of hydrogel bridges significantly enhances particle attraction, thereby increasing its macro-resistance to cracking.
{"title":"A two-scale study on the influence of biopolymer enhancement on drying granular materials","authors":"R. Chen, M. Veveakis","doi":"10.1680/jgele.23.00046","DOIUrl":"https://doi.org/10.1680/jgele.23.00046","url":null,"abstract":"Cracking resulting from drying (constrained dehydration) poses a significant challenge in geomaterials, impacting their mechanical performance. To address this problem, extensive efforts have been made to prevent or mitigate the occurrence of cracks, with recent attention focused on the utilisation of biopolymers. This letter investigates the influence of varying concentrations of the xanthan biopolymer on the mechanical response of granular materials, examining both macro and micro scales. The strength changes of the soil were evaluated through desiccation experiments, analysing the appearance and progression of failure on the macro scale. The findings of this study demonstrate that failure (cracking) progression is mitigated and eventually eliminated by increasing the concentration of the additive xanthan. Additionally, capillary experiments were conducted to assess the changes in attraction and the development of capillary bridges on the micro-scale. They indicate that the formation of hydrogel bridges significantly enhances particle attraction, thereby increasing its macro-resistance to cracking.","PeriodicalId":501470,"journal":{"name":"Géotechnique Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140302722","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}
This study focuses on characterizing the pore space in Tamusu mudstone, a preferred nuclear waste disposal host medium in China, using Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM). The investigation is conducted at the mesoscale, with a sample volume of 7.96 × 9.16 × 10.00 μm3 and voxel sizes of 5 × 5 × 10 nm3. The findings reveal that the pores in Tamusu mudstone primarily exist at the nanoscale, typically within its mineral matrix or at interfaces with non-porous minerals. At the FIB/SEM-imaged scale, the pore space in the Tamusu mudstone is mainly unconnected, with an analyzed porosity of approximately 3.5%. Pore characteristics within the specimen exhibit relative consistency within a box size of 6∼8 μm. Furthermore, the pore paths in Tamusu mudstone exhibit a preferred orientation within the bedding plane, suggesting anisotropy in pore space, possibly attributed to changes in pore path orientation and tortuosity.
{"title":"Pore space characterization of Tamusu mudstone based on FIB/SEM","authors":"H. Yu, D. Yang, Y. Song, J. Huang, X. Qiu","doi":"10.1680/jgele.23.00101","DOIUrl":"https://doi.org/10.1680/jgele.23.00101","url":null,"abstract":"This study focuses on characterizing the pore space in Tamusu mudstone, a preferred nuclear waste disposal host medium in China, using Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM). The investigation is conducted at the mesoscale, with a sample volume of 7.96 × 9.16 × 10.00 μm3 and voxel sizes of 5 × 5 × 10 nm3. The findings reveal that the pores in Tamusu mudstone primarily exist at the nanoscale, typically within its mineral matrix or at interfaces with non-porous minerals. At the FIB/SEM-imaged scale, the pore space in the Tamusu mudstone is mainly unconnected, with an analyzed porosity of approximately 3.5%. Pore characteristics within the specimen exhibit relative consistency within a box size of 6∼8 μm. Furthermore, the pore paths in Tamusu mudstone exhibit a preferred orientation within the bedding plane, suggesting anisotropy in pore space, possibly attributed to changes in pore path orientation and tortuosity.","PeriodicalId":501470,"journal":{"name":"Géotechnique Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139632009","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}
The finite element method is used to investigate the ultimate lateral pressure of snowflake pile in undrained clay in this paper. The effects of section geometry, lateral loading direction and pile-soil adhesion coefficient on the ultimate lateral pressure of snowflake pile are investigated by parametric analysis. The analysis results show that the normalized ultimate lateral pressure of snowflake pile gradually decreases as the flange length-thickness ratio λ increases, the normalized ultimate lateral pressure is linearly related to the pile-soil adhesion coefficient α, the normalized ultimate lateral pressure shows the trend of first decreasing and then increases with the increasing of lateral loading angle β. On this basis, the closed-form formula of the ultimate lateral pressure coefficient of snowflake pile is proposed. The research results can provide the basis for the design of snowflake pile in future.
{"title":"Finite element analysis of ultimate lateral pressure of snowflake pile in undrained clay","authors":"L. Gao, D. Lu, X. Gao","doi":"10.1680/jgele.23.00059","DOIUrl":"https://doi.org/10.1680/jgele.23.00059","url":null,"abstract":"The finite element method is used to investigate the ultimate lateral pressure of snowflake pile in undrained clay in this paper. The effects of section geometry, lateral loading direction and pile-soil adhesion coefficient on the ultimate lateral pressure of snowflake pile are investigated by parametric analysis. The analysis results show that the normalized ultimate lateral pressure of snowflake pile gradually decreases as the flange length-thickness ratio λ increases, the normalized ultimate lateral pressure is linearly related to the pile-soil adhesion coefficient α, the normalized ultimate lateral pressure shows the trend of first decreasing and then increases with the increasing of lateral loading angle β. On this basis, the closed-form formula of the ultimate lateral pressure coefficient of snowflake pile is proposed. The research results can provide the basis for the design of snowflake pile in future.","PeriodicalId":501470,"journal":{"name":"Géotechnique Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138616724","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}
Extensive field monitoring and a series of centrifuge model tests of grouting for rectangular pipe jacking were carried out to investigate the mechanism of grouting and its effects. An innovative jacking grouting device was developed to model the entire grouting process in centrifuge test. Validation work was carried out by comparing the ground settlement between the centrifuge model test results and the field results, and reasonable agreement was obtained. The experimental results show that grouting slurry with low fluid loss and high viscosity is more conducive to controlling ground settlement during tunnelling; the ground settlement is strongly influenced by the grouting pressure. Within a certain range, increasing grouting pressure is conducive to controlling settlement; however, excessive grouting pressure will lift the ground surface.
{"title":"Assessing grouting effects on ground settlement in rectangular pipe jacking: field monitoring and centrifuge model tests","authors":"M. Cao, X. Ma","doi":"10.1680/jgele.23.00056","DOIUrl":"https://doi.org/10.1680/jgele.23.00056","url":null,"abstract":"Extensive field monitoring and a series of centrifuge model tests of grouting for rectangular pipe jacking were carried out to investigate the mechanism of grouting and its effects. An innovative jacking grouting device was developed to model the entire grouting process in centrifuge test. Validation work was carried out by comparing the ground settlement between the centrifuge model test results and the field results, and reasonable agreement was obtained. The experimental results show that grouting slurry with low fluid loss and high viscosity is more conducive to controlling ground settlement during tunnelling; the ground settlement is strongly influenced by the grouting pressure. Within a certain range, increasing grouting pressure is conducive to controlling settlement; however, excessive grouting pressure will lift the ground surface.","PeriodicalId":501470,"journal":{"name":"Géotechnique Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138616233","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}
J.-L. Zhang, E.-C. Sun, P.-Z. Zhuang, H.-S. Yu, H. Yang
This letter develops an elastoplastic solution for cylindrical cavity contraction in unsaturated soils under constant suction conditions. The elastoplastic cavity contraction problem is formulated into a set of first-order ordinary differential equations (ODEs) by introducing a new auxiliary variable, which is solved as an initial value problem. The new solution is validated by comparison with numerical simulation results. Finally, parametric studies show that, as soil suction increases, the internal support pressure decreases faster with cavity contraction, the unloading-induced plastic zone becomes narrower, and the changes in effective stresses are smaller for a given tunnel convergence.
{"title":"Elastoplastic solution for cylindrical cavity contraction in unsaturated soils under constant suction conditions","authors":"J.-L. Zhang, E.-C. Sun, P.-Z. Zhuang, H.-S. Yu, H. Yang","doi":"10.1680/jgele.23.00080","DOIUrl":"https://doi.org/10.1680/jgele.23.00080","url":null,"abstract":"This letter develops an elastoplastic solution for cylindrical cavity contraction in unsaturated soils under constant suction conditions. The elastoplastic cavity contraction problem is formulated into a set of first-order ordinary differential equations (ODEs) by introducing a new auxiliary variable, which is solved as an initial value problem. The new solution is validated by comparison with numerical simulation results. Finally, parametric studies show that, as soil suction increases, the internal support pressure decreases faster with cavity contraction, the unloading-induced plastic zone becomes narrower, and the changes in effective stresses are smaller for a given tunnel convergence.","PeriodicalId":501470,"journal":{"name":"Géotechnique Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138988290","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}
With the goal of promoting the treatment and reuse of fly ash, a series of permeability tests were conducted to investigate the hydraulic conductivity (K) of polymer (chitosan, PEO, xanthan gum)-fly ash-kaolinite systems under different confining pressures and OCRs. The addition of fly ash increased the K of kaolinite due to changes in particle size and gradation, and the effect is not significant when the fly ash content is below 30%. PEO and xanthan gum increased the K of kaolinite, with xanthan gum having a more significant effect, while chitosan reduces it. For fly ash-kaolinite mixtures, chitosan and xanthan gum had negligible impact on the K, whereas PEO increased it by an order of magnitude. In addition, confining pressure restricts the flow channel while increasing the effective contact area between polymers and soil particles. The Koc/Knc of polymer-modified kaolinite rapidly converges at high OCRs, while the that of polymer-modified fly ash-kaolinite converges at low OCRs. This study provides insight into the effects of polymer modification on the hydraulic conductivity of fly ash-clay mixtures and provides guidance for the application of polymer modification technology in soil improvement.
{"title":"Permeability of polymer-modified kaolinite and fly ash-kaolinite mixtures under different confining pressures and OCRs","authors":"S.-L. Li, R.-J. He, X. Kang","doi":"10.1680/jgele.23.00058","DOIUrl":"https://doi.org/10.1680/jgele.23.00058","url":null,"abstract":"With the goal of promoting the treatment and reuse of fly ash, a series of permeability tests were conducted to investigate the hydraulic conductivity (K) of polymer (chitosan, PEO, xanthan gum)-fly ash-kaolinite systems under different confining pressures and OCRs. The addition of fly ash increased the K of kaolinite due to changes in particle size and gradation, and the effect is not significant when the fly ash content is below 30%. PEO and xanthan gum increased the K of kaolinite, with xanthan gum having a more significant effect, while chitosan reduces it. For fly ash-kaolinite mixtures, chitosan and xanthan gum had negligible impact on the K, whereas PEO increased it by an order of magnitude. In addition, confining pressure restricts the flow channel while increasing the effective contact area between polymers and soil particles. The Koc/Knc of polymer-modified kaolinite rapidly converges at high OCRs, while the that of polymer-modified fly ash-kaolinite converges at low OCRs. This study provides insight into the effects of polymer modification on the hydraulic conductivity of fly ash-clay mixtures and provides guidance for the application of polymer modification technology in soil improvement.","PeriodicalId":501470,"journal":{"name":"Géotechnique Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138626030","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}
G. Della Ragione, C. N. Abadie, X. Xu, T. S. da Silva Burke, T. Möller, E. Bilotta
Strain measurement inside the soil body in three-dimensional (3D) experiments is a real challenge for physical modellers in geotechnics. The use of fibre optic sensing offers the possibility of continuous measurement of the strain at depth with high spatial and temporal resolution in small-scale laboratory experiments. Despite the technology not being fully ready yet for centrifuge experiments, this is an important development in geotechnics. This paper explores the capacities of distributed fibre optic sensing (DFOS) as a solution for direct soil strain profile measurement at depth. A series of small-scale plane-strain experiments is used to simulate the simple case of the formation of a downwards subsidence. DFOS cables are laid in the soil specimen, and strains are directly compared with the soil movement, recorded with cameras through particle image velocimetry. Results indicate the ability of DFOS in detecting soil movements and underline the typical signature strain profile expected during this type of experiments. Finite-element analyses are carried out to further underpin the consequences of performing these tests at 1g and extend the findings to potential applications in 3D and on the geotechnical centrifuge. This shows promising results for detection of soil strain profiles inside the soil body in 3D.
{"title":"Fibre optic sensing for strain-field measurement in geotechnical laboratory experiments","authors":"G. Della Ragione, C. N. Abadie, X. Xu, T. S. da Silva Burke, T. Möller, E. Bilotta","doi":"10.1680/jgele.23.00048","DOIUrl":"https://doi.org/10.1680/jgele.23.00048","url":null,"abstract":"Strain measurement inside the soil body in three-dimensional (3D) experiments is a real challenge for physical modellers in geotechnics. The use of fibre optic sensing offers the possibility of continuous measurement of the strain at depth with high spatial and temporal resolution in small-scale laboratory experiments. Despite the technology not being fully ready yet for centrifuge experiments, this is an important development in geotechnics. This paper explores the capacities of distributed fibre optic sensing (DFOS) as a solution for direct soil strain profile measurement at depth. A series of small-scale plane-strain experiments is used to simulate the simple case of the formation of a downwards subsidence. DFOS cables are laid in the soil specimen, and strains are directly compared with the soil movement, recorded with cameras through particle image velocimetry. Results indicate the ability of DFOS in detecting soil movements and underline the typical signature strain profile expected during this type of experiments. Finite-element analyses are carried out to further underpin the consequences of performing these tests at 1<b><i>g</i></b> and extend the findings to potential applications in 3D and on the geotechnical centrifuge. This shows promising results for detection of soil strain profiles inside the soil body in 3D.","PeriodicalId":501470,"journal":{"name":"Géotechnique Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138535395","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}
Uncertainty in the measurement of the cone penetration test with pore-water pressure measurement (i.e. piezocone testing CPTU) can be caused by an equipment malfunction, poor calibration and maintenance of sensors, but also by a lack of saturation of the piezocone. The standards allow for many different options in terms of filters, saturation fluids and methodologies. The novel device described herein aims at measuring in a very simple manner the degree of saturation of the piezocone prior to testing. Because the quality of pore-water pressure measurements can currently only be assessed a posteriori – that is, after the test has been completed, or at best while testing, the methodology proposed herein has the potential to provide quality benchmarks for CPTU. The tool measures a parameter inspired by the well-established Skempton coefficient B, which is routinely used to estimate the sample saturation prior to laboratory testing. Furthermore, by performing the same measurement after a CPTU test, it is possible to assess whether saturation was lost during cone penetration. The paper describes a set of preliminary results that show a clear correlation between the saturation degree of filters and/or of the overall pore-pressure measurement system and the B parameter proposed, thus providing a proof of concept in laboratory settings.
{"title":"Novel procedure for measuring the saturation of the pore-pressure system in piezocone tips","authors":"I. Rocchi, M. Marcolongo, L. Tonni, G. Gottardi","doi":"10.1680/jgele.23.00034","DOIUrl":"https://doi.org/10.1680/jgele.23.00034","url":null,"abstract":"Uncertainty in the measurement of the cone penetration test with pore-water pressure measurement (i.e. piezocone testing CPTU) can be caused by an equipment malfunction, poor calibration and maintenance of sensors, but also by a lack of saturation of the piezocone. The standards allow for many different options in terms of filters, saturation fluids and methodologies. The novel device described herein aims at measuring in a very simple manner the degree of saturation of the piezocone prior to testing. Because the quality of pore-water pressure measurements can currently only be assessed <i>a posteriori</i> – that is, after the test has been completed, or at best while testing, the methodology proposed herein has the potential to provide quality benchmarks for CPTU. The tool measures a parameter inspired by the well-established Skempton coefficient <i>B</i>, which is routinely used to estimate the sample saturation prior to laboratory testing. Furthermore, by performing the same measurement after a CPTU test, it is possible to assess whether saturation was lost during cone penetration. The paper describes a set of preliminary results that show a clear correlation between the saturation degree of filters and/or of the overall pore-pressure measurement system and the <i>B</i> parameter proposed, thus providing a proof of concept in laboratory settings.","PeriodicalId":501470,"journal":{"name":"Géotechnique Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138535397","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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