Pub Date : 2024-09-04DOI: 10.1007/s11440-024-02396-8
Amir Sina Fouladi, Arul Arulrajah, Jian Chu, Annan Zhou, Suksun Horpibulsuk
Microbially induced calcium carbonate precipitation (MICP) is recognized as an eco-friendly approach in biological chemistry, offering significant potential for enhancing soil engineering properties. This study investigates the viability of MICP for stabilizing washed recycled sands (RS) sourced from construction and demolition wastes, offering significant potential for enhancing soil engineering properties and aligning this research study with sustainable waste management practices. Through meticulously designed laboratory experiments, this research examined the micro and macro biomineralization processes to assess the feasibility and factors influencing RS stabilization. The experimental setup evaluates the impact of cementation media concentration, ambient temperature, treatment cycles, and curing time on MICP-treated RS efficiency. The findings indicate that the optimal MICP conditions can be found at a cementation media concentration of 0.5 mol/L, an ambient temperature of 30 °C, and furthermore, up to 12 treatment cycles can significantly enhance the unconfined compressive strength (UCS) of RS to 724 kPa. In addition, extending the curing time results in a 28% increase in UCS compared to the initial strength of MICP-stabilized RS. Analyses via scanning electron microscopy and X-ray diffraction provide insights into the microstructural and mineralogical transformations that aid the biostabilization of RS. This research underscores the effectiveness of MICP-treated RS for usage as a geomaterial, emphasizing its environmental and practical benefits and furthermore advocates the sustainable usage of MICP for the biostabilization of RS for construction activities.
{"title":"Factors affecting the MICP stabilization of washed recycled sands derived from demolition wastes","authors":"Amir Sina Fouladi, Arul Arulrajah, Jian Chu, Annan Zhou, Suksun Horpibulsuk","doi":"10.1007/s11440-024-02396-8","DOIUrl":"https://doi.org/10.1007/s11440-024-02396-8","url":null,"abstract":"<p>Microbially induced calcium carbonate precipitation (MICP) is recognized as an eco-friendly approach in biological chemistry, offering significant potential for enhancing soil engineering properties. This study investigates the viability of MICP for stabilizing washed recycled sands (RS) sourced from construction and demolition wastes, offering significant potential for enhancing soil engineering properties and aligning this research study with sustainable waste management practices. Through meticulously designed laboratory experiments, this research examined the micro and macro biomineralization processes to assess the feasibility and factors influencing RS stabilization. The experimental setup evaluates the impact of cementation media concentration, ambient temperature, treatment cycles, and curing time on MICP-treated RS efficiency. The findings indicate that the optimal MICP conditions can be found at a cementation media concentration of 0.5 mol/L, an ambient temperature of 30 °C, and furthermore, up to 12 treatment cycles can significantly enhance the unconfined compressive strength (UCS) of RS to 724 kPa. In addition, extending the curing time results in a 28% increase in UCS compared to the initial strength of MICP-stabilized RS. Analyses via scanning electron microscopy and X-ray diffraction provide insights into the microstructural and mineralogical transformations that aid the biostabilization of RS. This research underscores the effectiveness of MICP-treated RS for usage as a geomaterial, emphasizing its environmental and practical benefits and furthermore advocates the sustainable usage of MICP for the biostabilization of RS for construction activities.</p>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"77 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-29DOI: 10.1007/s11440-024-02386-w
Barry Lehane
{"title":"Reply to discussion on “3D image-based method to measure soil stiffness in triaxial tests” Zewen Wang, Wenhan Du and B.M. Lehane","authors":"Barry Lehane","doi":"10.1007/s11440-024-02386-w","DOIUrl":"10.1007/s11440-024-02386-w","url":null,"abstract":"","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"19 11","pages":"7763 - 7765"},"PeriodicalIF":5.6,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142595479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-29DOI: 10.1007/s11440-024-02377-x
Kuang Cheng, Xinyu Ping, Buyao Han, Hao Wu, Hongshuai Liu
Deformation induced by finer particle loss is an important phenomenon during suffusion of gap-graded soils. This study focuses on the role of particle stress played in the particle loss-induced volumetric deformation. Discrete element simulations are performed to generate loss of finer particles with prescribed stress contribution, i.e. the contribution of particle stress to the macroscopic stress. Variations of volumetric strain, εv, with the stress contribution, Cσe, of eroded finer particles present two distinct patterns, that is, transition pattern, i.e. εv has extremely small values at relatively small Cσe and increases rapidly as Cσe exceeds the transition point near Cσe = 0.01%, and constant pattern, i.e. εv reaches a rather large value at extremely small Cσe and varies little with the increment of Cσe. A transformation from constant to transition pattern is observed for the εv–Cσe curves with the increment of the coordination number, Zstrong, of the load-carrying skeleton. The threshold of Zstrong for the transformation is around 3.71 for a relatively small eroded fraction (≤ 10%), while it is 3.96–4.09 for a relatively large eroded fraction (≥ 30%), in which the eroded fraction is the volume percentage of the eroded finer particles within the finer fraction.
{"title":"Study on particle loss-induced deformation of gap-graded soils: role of particle stress","authors":"Kuang Cheng, Xinyu Ping, Buyao Han, Hao Wu, Hongshuai Liu","doi":"10.1007/s11440-024-02377-x","DOIUrl":"https://doi.org/10.1007/s11440-024-02377-x","url":null,"abstract":"<p>Deformation induced by finer particle loss is an important phenomenon during suffusion of gap-graded soils. This study focuses on the role of particle stress played in the particle loss-induced volumetric deformation. Discrete element simulations are performed to generate loss of finer particles with prescribed stress contribution, i.e. the contribution of particle stress to the macroscopic stress. Variations of volumetric strain, <i>ε</i><sub><i>v</i></sub>, with the stress contribution, <i>C</i><sub><i>σ</i></sub><sup><i>e</i></sup>, of eroded finer particles present two distinct patterns, that is, transition pattern, i.e. <i>ε</i><sub><i>v</i></sub> has extremely small values at relatively small <i>C</i><sub><i>σ</i></sub><sup><i>e</i></sup> and increases rapidly as <i>C</i><sub><i>σ</i></sub><sup><i>e</i></sup> exceeds the transition point near <i>C</i><sub><i>σ</i></sub><sup><i>e</i></sup> = 0.01%, and constant pattern, i.e. <i>ε</i><sub><i>v</i></sub> reaches a rather large value at extremely small <i>C</i><sub><i>σ</i></sub><sup><i>e</i></sup> and varies little with the increment of <i>C</i><sub><i>σ</i></sub><sup><i>e</i></sup>. A transformation from constant to transition pattern is observed for the <i>ε</i><sub><i>v</i></sub>–<i>C</i><sub><i>σ</i></sub><sup><i>e</i></sup> curves with the increment of the coordination number, <i>Z</i><sub>strong</sub>, of the load-carrying skeleton. The threshold of <i>Z</i><sub>strong</sub> for the transformation is around 3.71 for a relatively small eroded fraction (≤ 10%), while it is 3.96–4.09 for a relatively large eroded fraction (≥ 30%), in which the eroded fraction is the volume percentage of the eroded finer particles within the finer fraction.</p>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"10 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cracking of compacted clays during cyclic wetting–drying poses significant challenges to the stability of channel slopes. This study performed a series of unidirectional wet-dry tests to evaluate the cracking behavior of expansive soils collected from a channel slope in northern Xinjiang, China. Using computed tomography scanning and three-dimensional (3D) reconstruction, the internal crack characteristics of expansive soils were quantitatively described. The results indicate that the penetration depth of the cracks was stabilized after five cycles, reaching 31.4% of the initial specimen height. The morphologies of internal cracks revealed a transition in the cracking mode, form shallow and scattered cracks in the initial stage to deeper and more clustered cracks in the final stage. Centralized cracks were prominent in the first three wet-dry cycles, followed by a shift to crack deflection from the vertical plane in subsequent cycles. Four indices (i.e., slice crack ratio, crack length, branching number, and dead-end point) provided a satisfactory quantitative depiction of the evolution of the spatial distribution and connectivity of the cracks over the number of cycles. Additionally, the crack volume fraction and fractal dimension effectively evaluated the 3D cracking behavior of soil crack networks.
{"title":"Cracking in compacted expansive soils under unidirectional wet-dry cycles: insights from X-ray computed tomography","authors":"Xun Zhu, Zheng Chen, Pengpeng Ni, Zheng-Yin Cai, Ying-Hao Huang, Chen Zhang","doi":"10.1007/s11440-024-02394-w","DOIUrl":"https://doi.org/10.1007/s11440-024-02394-w","url":null,"abstract":"<p>Cracking of compacted clays during cyclic wetting–drying poses significant challenges to the stability of channel slopes. This study performed a series of unidirectional wet-dry tests to evaluate the cracking behavior of expansive soils collected from a channel slope in northern Xinjiang, China. Using computed tomography scanning and three-dimensional (3D) reconstruction, the internal crack characteristics of expansive soils were quantitatively described. The results indicate that the penetration depth of the cracks was stabilized after five cycles, reaching 31.4% of the initial specimen height. The morphologies of internal cracks revealed a transition in the cracking mode, form shallow and scattered cracks in the initial stage to deeper and more clustered cracks in the final stage. Centralized cracks were prominent in the first three wet-dry cycles, followed by a shift to crack deflection from the vertical plane in subsequent cycles. Four indices (i.e., slice crack ratio, crack length, branching number, and dead-end point) provided a satisfactory quantitative depiction of the evolution of the spatial distribution and connectivity of the cracks over the number of cycles. Additionally, the crack volume fraction and fractal dimension effectively evaluated the 3D cracking behavior of soil crack networks.</p>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"4 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-29DOI: 10.1007/s11440-024-02393-x
Chen Xu, Caichu Xia
The “yield-resist” combined support measure is a widely employed control measure in soft rock tunnels for controlling large deformation, particularly in high geostress conditions. For strain-softening rock masses, the strength parameters in the plastic zone are coupled with the support reaction. Due to the complexity of the interaction mechanism between yielding support and strain-softening surrounding rock, the majority of current solutions are based on the plane–strain model. However, the advancement of the tunnel is a three-dimensional problem. Therefore, the longitudinal effect is worthy of discussion when analyzing the mechanical behaviors of strain-softening rock and yielding support. A new two-stage method is proposed to describe the interaction between strain-softening rock mass and yielding support based on the generalized Zhang–Zhu (GZZ) strength criterion. Firstly, a simplified mechanical model of the yielding support structure is suggested to describe the mechanical response of the surrounding rock and support. Subsequently, a semi-analytical solution to three-dimensional ground–support interaction is proposed, taking into account the longitudinal effect. The results of the proposed solution are compared with those of a finite element simulation, and a high degree of agreement is observed. Finally, the mechanical behaviors of different yielding supports are discussed. The findings indicate that postponing the support timing by means of yielding technologies is essential, as otherwise the support would bear a very large load. The second stage of support reaction can be significantly reduced by implementing the “control-yield-resist” (CYR) support. The research offers novel insights and methodologies for investigating the three-dimensional interaction between the surrounding rock and various tunnel supports in high geostress conditions.
{"title":"Interaction between yielding tunnel support and strain-softening rock mass based on the three-dimensional strength criterion","authors":"Chen Xu, Caichu Xia","doi":"10.1007/s11440-024-02393-x","DOIUrl":"https://doi.org/10.1007/s11440-024-02393-x","url":null,"abstract":"<p>The “yield-resist” combined support measure is a widely employed control measure in soft rock tunnels for controlling large deformation, particularly in high geostress conditions. For strain-softening rock masses, the strength parameters in the plastic zone are coupled with the support reaction. Due to the complexity of the interaction mechanism between yielding support and strain-softening surrounding rock, the majority of current solutions are based on the plane–strain model. However, the advancement of the tunnel is a three-dimensional problem. Therefore, the longitudinal effect is worthy of discussion when analyzing the mechanical behaviors of strain-softening rock and yielding support. A new two-stage method is proposed to describe the interaction between strain-softening rock mass and yielding support based on the generalized Zhang–Zhu (GZZ) strength criterion. Firstly, a simplified mechanical model of the yielding support structure is suggested to describe the mechanical response of the surrounding rock and support. Subsequently, a semi-analytical solution to three-dimensional ground–support interaction is proposed, taking into account the longitudinal effect. The results of the proposed solution are compared with those of a finite element simulation, and a high degree of agreement is observed. Finally, the mechanical behaviors of different yielding supports are discussed. The findings indicate that postponing the support timing by means of yielding technologies is essential, as otherwise the support would bear a very large load. The second stage of support reaction can be significantly reduced by implementing the “control-yield-resist” (CYR) support. The research offers novel insights and methodologies for investigating the three-dimensional interaction between the surrounding rock and various tunnel supports in high geostress conditions.</p>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"20 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-28DOI: 10.1007/s11440-024-02391-z
Lin-Yong Cui, Wei-Min Ye, Qiong Wang, Yong-Gui Chen, Yu-Jun Cui
Understanding impacts of gas breakthrough processes on the sealing ability of the bentonite buffer/backfill materials is crucial for the safety evaluation of the nuclear waste geological repository. In this work, the residual capillary pressure method was utilized to conduct successive gas breakthrough tests on compacted Gaomiaozi bentonite specimens. During each gas breakthrough test, the upstream gas pressure was increased in a step-by-step way until the gas breakthrough was recorded. Water permeability tests were performed before each gas breakthrough to ensure that the bentonite specimen was fully saturated. Finally, after experienced five successive gas breakthrough processes, the bentonite specimen was submitted for the mercury intrusion porosimetry (MIP) test. For comparison, four other parallel specimens that experienced one to four gas breakthroughs, respectively, were also submitted for the MIP tests to examine the possible damage of the bentonite matrix resulted from gas breakthrough processes. Results show that, during the first three successive gas breakthrough tests, the gas breakthrough pressure and the snap-off pressure decreased rapidly from 4.46 to 3.66 MPa and from 0.51 to 0.26 MPa, respectively. An exponential decrease in the maximum effective gas permeability from 3.75 × 10–18 to 3.17 × 10–19 m2 with gas breakthroughs experienced could also be observed. On contrary, both of the saturated water permeability and the pore size distribution show little difference as compared to its initial value. These results indicate that gas breakthrough process could induce a degradation of gas-tightness capacity of the bentonite specimen. Meanwhile, the gas injection pressure was reset to zero before conducting the water permeability test. Reducing the gas pressure will induce a contraction in the radius of the gas pathway, even leading to complete closure. Consequently, the water permeability and the pore size distribution remained almost unchanged.
{"title":"Investigation on successive gas breakthroughs behavior of saturated GMZ bentonite under rigid boundary conditions","authors":"Lin-Yong Cui, Wei-Min Ye, Qiong Wang, Yong-Gui Chen, Yu-Jun Cui","doi":"10.1007/s11440-024-02391-z","DOIUrl":"10.1007/s11440-024-02391-z","url":null,"abstract":"<div><p>Understanding impacts of gas breakthrough processes on the sealing ability of the bentonite buffer/backfill materials is crucial for the safety evaluation of the nuclear waste geological repository. In this work, the residual capillary pressure method was utilized to conduct successive gas breakthrough tests on compacted Gaomiaozi bentonite specimens. During each gas breakthrough test, the upstream gas pressure was increased in a step-by-step way until the gas breakthrough was recorded. Water permeability tests were performed before each gas breakthrough to ensure that the bentonite specimen was fully saturated. Finally, after experienced five successive gas breakthrough processes, the bentonite specimen was submitted for the mercury intrusion porosimetry (MIP) test. For comparison, four other parallel specimens that experienced one to four gas breakthroughs, respectively, were also submitted for the MIP tests to examine the possible damage of the bentonite matrix resulted from gas breakthrough processes. Results show that, during the first three successive gas breakthrough tests, the gas breakthrough pressure and the snap-off pressure decreased rapidly from 4.46 to 3.66 MPa and from 0.51 to 0.26 MPa, respectively. An exponential decrease in the maximum effective gas permeability from 3.75 × 10<sup>–18</sup> to 3.17 × 10<sup>–19</sup> m<sup>2</sup> with gas breakthroughs experienced could also be observed. On contrary, both of the saturated water permeability and the pore size distribution show little difference as compared to its initial value. These results indicate that gas breakthrough process could induce a degradation of gas-tightness capacity of the bentonite specimen. Meanwhile, the gas injection pressure was reset to zero before conducting the water permeability test. Reducing the gas pressure will induce a contraction in the radius of the gas pathway, even leading to complete closure. Consequently, the water permeability and the pore size distribution remained almost unchanged.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"19 10","pages":"6773 - 6786"},"PeriodicalIF":5.6,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-20DOI: 10.1007/s11440-024-02385-x
Brendan C. O’Kelly, Stuart K. Haigh
This communication presents a critical discussion of the article “Undrained shear strength prediction of clays using liquidity index”, authored by Q. Wang, S. Qiu, H. Zheng, R. Zhang, and recently published in Acta Geotechnica (https://doi.org/10.1007/s11440-023-02107-9). Various inaccurate claims and flaws regarding the Authors’ newly developed three-parameter strength–liquidity index (Su–IL) models/correlations are highlighted and discussed herein. In particular, comparing existing two-parameter and their newly developed three-parameter Su–IL models, contrary to the Authors’ claims, no improvement in prediction accuracy is achieved over the two-parameter model by introducing a third model parameter. Rather, it is shown herein that the existing two-parameter and the Authors’ three-parameter Su–IL models are mathematically identical. Furthermore, two of the Authors’ newly developed Su–IL correlations, i.e., relating the triaxial-compression and shearbox derived strengths to the liquidity index, are shown to be inaccurate, forecasting gross under- and over-predictions of the measured strengths, respectively. This highlights the need for a reassessment of the proposed correlations, and emphasizes the importance of accurate and reliable correlations in geotechnical engineering.
{"title":"Discussion to the article Undrained shear strength prediction of clays using liquidity index, by Q. Wang, S. Qiu, H. Zheng, R. Zhang","authors":"Brendan C. O’Kelly, Stuart K. Haigh","doi":"10.1007/s11440-024-02385-x","DOIUrl":"https://doi.org/10.1007/s11440-024-02385-x","url":null,"abstract":"<p>This communication presents a critical discussion of the article “Undrained shear strength prediction of clays using liquidity index”, authored by Q. Wang, S. Qiu, H. Zheng, R. Zhang, and recently published in <i>Acta Geotechnica</i> (https://doi.org/10.1007/s11440-023-02107-9). Various inaccurate claims and flaws regarding the Authors’ newly developed three-parameter strength–liquidity index (<i>S</i><sub><i>u</i></sub>–<i>I</i><sub><i>L</i></sub>) models/correlations are highlighted and discussed herein. In particular, comparing existing two-parameter and their newly developed three-parameter <i>S</i><sub><i>u</i></sub>–<i>I</i><sub><i>L</i></sub> models, contrary to the Authors’ claims, no improvement in prediction accuracy is achieved over the two-parameter model by introducing a third model parameter. Rather, it is shown herein that the existing two-parameter and the Authors’ three-parameter <i>S</i><sub><i>u</i></sub>–<i>I</i><sub><i>L</i></sub> models are mathematically identical. Furthermore, two of the Authors’ newly developed <i>S</i><sub><i>u</i></sub>–<i>I</i><sub><i>L</i></sub> correlations, i.e., relating the triaxial-compression and shearbox derived strengths to the liquidity index, are shown to be inaccurate, forecasting gross under- and over-predictions of the measured strengths, respectively. This highlights the need for a reassessment of the proposed correlations, and emphasizes the importance of accurate and reliable correlations in geotechnical engineering.</p>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"38 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-20DOI: 10.1007/s11440-024-02379-9
Lin Li
Wang et al. (2024) proposed a new method to measure soil stiffness through triaxial tests. This discussion illustrates some limitations of the proposed method and details several modifications on the post-image analysis process to enhance its capability. These modifications include the introduction of true stereophotogrammetry for camera and triaxial cell wall orientation, optical ray tracing technique for optical ray reconstruction, and three-dimensional digital image correlation (3D-DIC) for full-field two-dimensional (2D) point cloud generation. With these modifications, the capability of the new method can be significantly improved from only local strain to full-field deformation measurement at a higher accuracy and resolution.
Wang 等人(2024 年)提出了一种通过三轴试验测量土壤刚度的新方法。本讨论说明了所提方法的一些局限性,并详细介绍了为提高其能力而对图像后分析过程进行的若干修改。这些修改包括:采用真正的立体摄影测量法确定相机和三轴细胞壁的方向;采用光学射线追踪技术进行光学射线重建;采用三维数字图像相关技术(3D-DIC)生成全场二维(2D)点云。通过这些改进,新方法的能力得到显著提高,从仅测量局部应变提高到更高精度和分辨率的全场变形测量。
{"title":"Discussion of “A 3D image-based method to measure soil stiffness in triaxial tests” by Wang et al. 2024 (DOI: /10.1007/s11440-023-01977-3)","authors":"Lin Li","doi":"10.1007/s11440-024-02379-9","DOIUrl":"10.1007/s11440-024-02379-9","url":null,"abstract":"<div><p>Wang et al. (2024) proposed a new method to measure soil stiffness through triaxial tests. This discussion illustrates some limitations of the proposed method and details several modifications on the post-image analysis process to enhance its capability. These modifications include the introduction of true stereophotogrammetry for camera and triaxial cell wall orientation, optical ray tracing technique for optical ray reconstruction, and three-dimensional digital image correlation (3D-DIC) for full-field two-dimensional (2D) point cloud generation. With these modifications, the capability of the new method can be significantly improved from only local strain to full-field deformation measurement at a higher accuracy and resolution.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"19 11","pages":"7759 - 7761"},"PeriodicalIF":5.6,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-20DOI: 10.1007/s11440-024-02380-2
Wei Sun, Yucheng Li, Guoping Zhang
Ren et al. (Acta Geotech, 2023. https://doi.org/10.1007/s11440-023-01967-5) recently reported an interesting experimental investigation of the thixotropism, or thixotropy mechanism, of a deep-sea marine clay, conclusively claiming that the conversion of weakly and strongly bound waters to free water, in addition to microfabric change, contributes to the thixotropic hardening of the studied clay. While the microfabric evolution of the clay during the thixotropic hardening process was observed, in a speculative and qualitative fashion, using scanning electron microscopy, the interconversion of different types of waters (i.e., weakly bound water, strongly bound water, and free water) in the clay was quantitatively assessed using thermogravimetric analysis (TGA) and qualitatively judged by Fourier transform infrared spectroscopy (FTIR). However, some fundamental issues related to the viability and suitability of the employed experimental techniques and the interpretation of TGA and FTIR results arise and are worth re-examination and discussion. In this short communication, the TGA curves and FTIR spectra were re-interpreted, based on a mathematically more accurate and scientifically more rigorous analysis of the data, which appears to make the proposed model of evolution of different types of waters in clays invalid. Consequently, the attribution of thixotropy or one potential thixotropism to the conversion among different types of waters and the conclusions drawn based on the speculative interpretations are also worth further clarifying and commenting. Overall, the TGA and FTIR results probably fail to conclusively establish the conversion among the different types of waters occurring along with the thixotropic hardening process.
{"title":"Comment on “Experimental study on the thixotropic mechanism of deep-sea clay from the perspective of microstructure and bound water” by Ren et al. (2023), Acta Geotechnica, https://doi.org/10.1007/s11440-023-01967-5","authors":"Wei Sun, Yucheng Li, Guoping Zhang","doi":"10.1007/s11440-024-02380-2","DOIUrl":"https://doi.org/10.1007/s11440-024-02380-2","url":null,"abstract":"<p>Ren et al. (Acta Geotech, 2023. https://doi.org/10.1007/s11440-023-01967-5) recently reported an interesting experimental investigation of the thixotropism, or thixotropy mechanism, of a deep-sea marine clay, conclusively claiming that the conversion of weakly and strongly bound waters to free water, in addition to microfabric change, contributes to the thixotropic hardening of the studied clay. While the microfabric evolution of the clay during the thixotropic hardening process was observed, in a speculative and qualitative fashion, using scanning electron microscopy, the interconversion of different types of waters (i.e., weakly bound water, strongly bound water, and free water) in the clay was quantitatively assessed using thermogravimetric analysis (TGA) and qualitatively judged by Fourier transform infrared spectroscopy (FTIR). However, some fundamental issues related to the viability and suitability of the employed experimental techniques and the interpretation of TGA and FTIR results arise and are worth re-examination and discussion. In this short communication, the TGA curves and FTIR spectra were re-interpreted, based on a mathematically more accurate and scientifically more rigorous analysis of the data, which appears to make the proposed model of evolution of different types of waters in clays invalid. Consequently, the attribution of thixotropy or one potential thixotropism to the conversion among different types of waters and the conclusions drawn based on the speculative interpretations are also worth further clarifying and commenting. Overall, the TGA and FTIR results probably fail to conclusively establish the conversion among the different types of waters occurring along with the thixotropic hardening process.</p>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"415 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-18DOI: 10.1007/s11440-024-02382-0
Mengmeng Lu, Jinxin Sun, Minjie Wen, Kang Yang, Kuo Li
The evaluation of thermo-hydro-mechanical (THM) coupling response of clayey soils has emerged as an imperative research focus within thermal-related geotechnical engineering. Clays will exhibit nonlinear physical and mechanical behavior when subjected to variations in effective stress and temperature. Additionally, temperature gradient within soils can induce additional pore water migration, thereby resulting in a significant thermo-osmosis effect. Indeed, thermal consolidation of clayey soils constitutes a complicated THM coupling issue, whereas the theoretical investigation into it currently remains insufficiently developed. In this context, a one-dimensional mathematical model for the nonlinear thermal consolidation of saturated clay is proposed, which comprehensively incorporates the crucial THM coupling characteristics under the combined effects of heating and mechanical loading. In current model, the interaction between nonlinear consolidation and heat transfer process is captured. Heat transfer within saturated clay is investigated by accounting for the conduction, advection, and thermomechanical dispersion. The resulting governing equations and numerical solutions are derived through assuming impeded drainage boundaries. Then, the reasonability of current model is validated by degradation and simulation analysis. Subsequently, an in-depth assessment is carried out to investigate the influence of crucial parameters on the nonlinear consolidation behavior. The results indicate that increasing the temperature can significantly promote the consolidation process of saturated clay, the dissipation rate of excess pore water pressure (EPWP) is accelerated by a maximum of approximately 15%. Moreover, the dissipation rate of EPWP also increases with the increment of pre-consolidation pressure, while the corresponding settlement decreases. Finally, the consolidation performance is remarkably impacted by thermo-osmosis and neglecting this process will generate a substantial departure from engineering practice.
{"title":"Insight into nonlinear thermal consolidation of saturated clay under coupled thermo-mechanical loading: a unified one-dimensional model","authors":"Mengmeng Lu, Jinxin Sun, Minjie Wen, Kang Yang, Kuo Li","doi":"10.1007/s11440-024-02382-0","DOIUrl":"https://doi.org/10.1007/s11440-024-02382-0","url":null,"abstract":"<p>The evaluation of thermo-hydro-mechanical (THM) coupling response of clayey soils has emerged as an imperative research focus within thermal-related geotechnical engineering. Clays will exhibit nonlinear physical and mechanical behavior when subjected to variations in effective stress and temperature. Additionally, temperature gradient within soils can induce additional pore water migration, thereby resulting in a significant thermo-osmosis effect. Indeed, thermal consolidation of clayey soils constitutes a complicated THM coupling issue, whereas the theoretical investigation into it currently remains insufficiently developed. In this context, a one-dimensional mathematical model for the nonlinear thermal consolidation of saturated clay is proposed, which comprehensively incorporates the crucial THM coupling characteristics under the combined effects of heating and mechanical loading. In current model, the interaction between nonlinear consolidation and heat transfer process is captured. Heat transfer within saturated clay is investigated by accounting for the conduction, advection, and thermomechanical dispersion. The resulting governing equations and numerical solutions are derived through assuming impeded drainage boundaries. Then, the reasonability of current model is validated by degradation and simulation analysis. Subsequently, an in-depth assessment is carried out to investigate the influence of crucial parameters on the nonlinear consolidation behavior. The results indicate that increasing the temperature can significantly promote the consolidation process of saturated clay, the dissipation rate of excess pore water pressure (EPWP) is accelerated by a maximum of approximately 15%. Moreover, the dissipation rate of EPWP also increases with the increment of pre-consolidation pressure, while the corresponding settlement decreases. Finally, the consolidation performance is remarkably impacted by thermo-osmosis and neglecting this process will generate a substantial departure from engineering practice.</p>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"117 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}