Pub Date : 2025-04-08DOI: 10.1016/j.sandf.2025.101613
Joyce Nakayenga , Nozomi Omaki , Daehyun Kim , Toshiro Hata
Steel slag, a by-product of steel making, is increasingly used in geotechnical construction due to its reactivity with silica and alumina in clays. Volcanic and diatom silica have various effects on the strength development of steel slag. As the effects of amorphous silica and the diatom density on the unconfined compressive strength (UCS) and seawater durability of steel slag-treated clays have not been established, this study addressed them. The relationship was confirmed using six steel slag-treated clay samples, air-dried at 20 °C for 28 and 56 days, and three cement- or steel slag-treated clay samples, exposed to seawater for 0, 28, and 90 days. The amorphous silica showed a weak correlation with the UCS, while the diatom density showed a strong relationship with it. No correlation at all was found between the diatom density and the loss on ignition, implicating cyanobacteria as the potential cause of the UCS reduction. Further research is needed to investigate the long-term effects of seawater exposure on the durability of both cement-treated and steel slag-treated clays, given that a correlation has been found between a decrease in UCS with a lower diatom density in cement-treated clays, but not in steel slag-treated clays.
{"title":"Influence of diatom-amorphous silica on strength and durability of steel slag and cement-treated clays","authors":"Joyce Nakayenga , Nozomi Omaki , Daehyun Kim , Toshiro Hata","doi":"10.1016/j.sandf.2025.101613","DOIUrl":"10.1016/j.sandf.2025.101613","url":null,"abstract":"<div><div>Steel slag, a by-product of steel making, is increasingly used in geotechnical construction due to its reactivity with silica and alumina in clays. Volcanic and diatom silica have various effects on the strength development of steel slag. As the effects of amorphous silica and the diatom density on the unconfined compressive strength (UCS) and seawater durability of steel slag-treated clays have not been established, this study addressed them. The relationship was confirmed using six steel slag-treated clay samples, air-dried at 20 °C for 28 and 56 days, and three cement- or steel slag-treated clay samples, exposed to seawater for 0, 28, and 90 days. The amorphous silica showed a weak correlation with the UCS, while the diatom density showed a strong relationship with it. No correlation at all was found between the diatom density and the loss on ignition, implicating cyanobacteria as the potential cause of the UCS reduction. Further research is needed to investigate the long-term effects of seawater exposure on the durability of both cement-treated and steel slag-treated clays, given that a correlation has been found between a decrease in UCS with a lower diatom density in cement-treated clays, but not in steel slag-treated clays.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 3","pages":"Article 101613"},"PeriodicalIF":3.3,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143792304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-07DOI: 10.1016/j.sandf.2025.101612
Zhengyao He, Nicolas G.L.H. Lee, S.P. Gopal Madabhushi
With increased demand for urban space, there is a growing propensity to move urban lifeline systems such as Metro systems and utilities to shallow, cut-and-cover tunnels. The seismic behaviour of such rectangular tunnels is important as these systems need to remain operational in the period after the earthquake for emergency rescue & recovery operations. In this paper, the main focus will be on determining the seismic response of shallow, rectangular tunnels that are buried in loose dry or saturated sand layers, and clay layers with different undrained shear strengths. The results from four centrifuge testing campaigns will be presented. The dynamic responses of the tunnel and soil will be compared to the input motion. The tunnel movements and soil deformations during seismic loading were obtained using high-resolution, high-speed imaging in combination with GeoPIV-RG software. Finally, conclusions will be drawn on the effects of the soil strata through which the tunnel passes, based on these centrifuge data that simulate the most critical geological conditions.
{"title":"Seismic behaviour of shallow cut-and-cover tunnels","authors":"Zhengyao He, Nicolas G.L.H. Lee, S.P. Gopal Madabhushi","doi":"10.1016/j.sandf.2025.101612","DOIUrl":"10.1016/j.sandf.2025.101612","url":null,"abstract":"<div><div>With increased demand for urban space, there is a growing propensity to move urban lifeline systems such as Metro systems and utilities to shallow, cut-and-cover tunnels. The seismic behaviour of such rectangular tunnels is important as these systems need to remain operational in the period after the earthquake for emergency rescue & recovery operations. In this paper, the main focus will be on determining the seismic response of shallow, rectangular tunnels that are buried in loose dry or saturated sand layers, and clay layers with different undrained shear strengths. The results from four centrifuge testing campaigns will be presented. The dynamic responses of the tunnel and soil will be compared to the input motion. The tunnel movements and soil deformations during seismic loading were obtained using high-resolution, high-speed imaging in combination with GeoPIV-RG software. Finally, conclusions will be drawn on the effects of the soil strata through which the tunnel passes, based on these centrifuge data that simulate the most critical geological conditions.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 3","pages":"Article 101612"},"PeriodicalIF":3.3,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143786031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-04DOI: 10.1016/j.sandf.2025.101616
Juan Du , Xingfei Jiang , Bingyang Liu , Tao Li , Ningjun Jiang
In Hainan Province, China, the unique geographical location presents significant challenges to the safety of coastal infrastructure due to complex dynamic loads such as waves, sea breeze and earthquake. A type of organic matter-rich and poorly graded organic-matter-disseminated sand (OMDS) is commonly found in this region. The existence of OMDS can reduce the bearing capacity of composite foundation and may even lead to structural failure. Currently, there is insufficient understanding regarding this type of sand. This article characterizes the dynamic parameters of OMDS through dynamic elastic modulus (Ed) and damping ratio (λ). A series of undrained cyclic triaxial shear tests were carried out on OMDS specimens with varying compaction energy, initial confining pressure and consolidation ratios. Based on these experiments, a modified Hardin-Drnevich model is presented to explain the dynamic constitutive relation. Furthermore, the impacts of compaction energy, initial confining pressure, and consolidation ratio on skeleton curve, Ed, normalized dynamic elastic modulus (Ed/Edmax) and λ are systematically discussed. The results show that dynamic axial stress (σd), Ed, Ed/Edmax and λ are all proportional to the compaction energy; lower compaction energy results in earlier stiffness deterioration. As confining pressure increases, σd and Ed rise, while λ decreases, with Ed /Edmax being less affected. Finally, empirical models with respect of the varied parameters are proposed to estimate the maximum dynamic elastic modulus (Edmax) and maximum damping ratio (λmax), yielding relatively accurate estimation results. This study provides new insights into the dynamic properties of bay facies sand enriched with organic matter, which may facilitate the design and application of this type of sand in coastal projects.
{"title":"Dynamic modulus and damping ratio of organic-matter-disseminated sand under cyclic triaxial condition","authors":"Juan Du , Xingfei Jiang , Bingyang Liu , Tao Li , Ningjun Jiang","doi":"10.1016/j.sandf.2025.101616","DOIUrl":"10.1016/j.sandf.2025.101616","url":null,"abstract":"<div><div>In Hainan Province, China, the unique geographical location presents significant challenges to the safety of coastal infrastructure due to complex dynamic loads such as waves, sea breeze and earthquake. A type of organic matter-rich and poorly graded organic-matter-disseminated sand (OMDS) is commonly found in this region. The existence of OMDS can reduce the bearing capacity of composite foundation and may even lead to structural failure. Currently, there is insufficient understanding regarding this type of sand. This article characterizes the dynamic parameters of OMDS through dynamic elastic modulus (<em>E</em><sub>d</sub>) and damping ratio (<em>λ</em>). A series of undrained cyclic triaxial shear tests were carried out on OMDS specimens with varying compaction energy, initial confining pressure and consolidation ratios. Based on these experiments, a modified Hardin-Drnevich model is presented to explain the dynamic constitutive relation. Furthermore, the impacts of compaction energy, initial confining pressure, and consolidation ratio on skeleton curve, <em>E</em><sub>d</sub>, normalized dynamic elastic modulus (<em>E</em><sub>d</sub>/<em>E</em><sub>dmax</sub>) and <em>λ</em> are systematically discussed. The results show that dynamic axial stress (<em>σ</em><sub>d</sub>), <em>E</em><sub>d</sub>, <em>E</em><sub>d</sub>/<em>E</em><sub>dmax</sub> and <em>λ</em> are all proportional to the compaction energy; lower compaction energy results in earlier stiffness deterioration. As confining pressure increases, <em>σ</em><sub>d</sub> and <em>E</em><sub>d</sub> rise, while <em>λ</em> decreases, with <em>E</em><sub>d</sub> /<em>E</em><sub>dmax</sub> being less affected. Finally, empirical models with respect of the varied parameters are proposed to estimate the maximum dynamic elastic modulus (<em>E</em><sub>dmax</sub>) and maximum damping ratio (<em>λ</em> <sub>max</sub>), yielding relatively accurate estimation results. This study provides new insights into the dynamic properties of bay facies sand enriched with organic matter, which may facilitate the design and application of this type of sand in coastal projects.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 3","pages":"Article 101616"},"PeriodicalIF":3.3,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-22DOI: 10.1016/j.sandf.2025.101594
Zheng Fan , Yoichi Watabe
Due to economic and demographic growth, there is a rising demand for land reclamation in coastal cities of East and Southeast Asia. Marine clays typically play a critical role in these projects, and the deformation characteristics of marine clays become a crucial problem in terms of the quality of the subsoil conditions. The long-term loading behavior of marine clays has been studied by many researchers. However, relatively few studies have been done on the unloading behavior of these clays after preloading; and thus, the strain rate dependency on the unloading behavior of marine clays remains unclear. The aim of this study was to accumulate experimental data on the unloading behavior of marine clays and to develop a strain rate-based model for improving the accuracy of the predictions of the swelling behavior of marine clays during unloading. The authors conducted a series of constant rate of strain (CRS) consolidation tests from loading to unloading, and long-term unloading oedometer tests on Ariake clay, which is a well-known sensitive marine clay, to observe the swelling behavior during in unloading. The preloading time, corresponding to different strain rates at the end of preloading, was controlled to elucidate the effect of the stress history. Moreover, instead of parameter σ′p (preconsolidation pressure) for the normal consolidation visco-plastic behavior, the authors developed and proposed a new visco-plastic model by introducing the concept of a plastic rebound boundary and a new parameter R for swelling behavior during unloading. Parameter R represents the normalized distance from the current stress state to the plastic rebound boundary in logarithmic effective consolidation stress. Therefore, the visco-plastic model for the behavior in the loading stage was developed into the swelling visco-plastic behavior in the unloading stage for Ariake clay. Comparing the simulation and test results, the simplified visco-plastic swelling model was found to agree well with the test results.
{"title":"Experimental study for modeling the unloading swelling behavior of Ariake clay","authors":"Zheng Fan , Yoichi Watabe","doi":"10.1016/j.sandf.2025.101594","DOIUrl":"10.1016/j.sandf.2025.101594","url":null,"abstract":"<div><div>Due to economic and demographic growth, there is a rising demand for land reclamation in coastal cities of East and Southeast Asia. Marine clays typically play a critical role in these projects, and the deformation characteristics of marine clays become a crucial problem in terms of the quality of the subsoil conditions. The long-term loading behavior of marine clays has been studied by many researchers. However, relatively few studies have been done on the unloading behavior of these clays after preloading; and thus, the strain rate dependency on the unloading behavior of marine clays remains unclear. The aim of this study was to accumulate experimental data on the unloading behavior of marine clays and to develop a strain rate-based model for improving the accuracy of the predictions of the swelling behavior of marine clays during unloading. The authors conducted a series of constant rate of strain (CRS) consolidation tests from loading to unloading, and long-term unloading oedometer tests on Ariake clay, which is a well-known sensitive marine clay, to observe the swelling behavior during in unloading. The preloading time, corresponding to different strain rates at the end of preloading, was controlled to elucidate the effect of the stress history. Moreover, instead of parameter <em>σ′</em><sub>p</sub> (preconsolidation pressure) for the normal consolidation visco-plastic behavior, the authors developed and proposed a new visco-plastic model by introducing the concept of a plastic rebound boundary and a new parameter <em>R</em> for swelling behavior during unloading. Parameter <em>R</em> represents the normalized distance from the current stress state to the plastic rebound boundary in logarithmic effective consolidation stress. Therefore, the visco-plastic model for the behavior in the loading stage was developed into the swelling visco-plastic behavior in the unloading stage for Ariake clay. Comparing the simulation and test results, the simplified visco-plastic swelling model was found to agree well with the test results.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 3","pages":"Article 101594"},"PeriodicalIF":3.3,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143686649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Extensive liquefaction took place in Minami-Kurihashi, Kuki City, Saitama, Japan during the 2011 Off the Pacific Coast of Tohoku Earthquake, which induced damage to houses and infrastructures. Based on the results of a detailed geotechnical investigation, the ground water lowering method has been adopted and executed as a countermeasure against liquefaction. This report summarizes how this countermeasure could be implemented, including the results from field monitoring and relevant analyses of the local ground water level and surface settlement that were conducted during and after the ground water lowering. By newly installing a network of drainage ditches, cut-off sheet pile walls, and operating manhole pumps, it was possible to lower the ground water level in order to prevent/reduce future liquefaction damage. In the non-execution areas outside the cut-off walls, the ground water level was not affected by this operation. As of the end of the monitoring period, the measured maximum settlement and tilting ratio were 36 mm and 1.03/1000, respectively. All the monitoring data satisfied the pre-assigned control limits of 40 mm and 2/1000, respectively. In order to numerically simulate the monitored behavior, modification of the compression index and coefficient of permeability was required. Based on the results of a long-term behavior analysis using the modified parameters, the final settlement and tilting ratio were predicted to be, at maximum, 54 mm and 1.50/1000, respectively. The latter value satisfied the pre-assigned threshold limit of 3/1000.
{"title":"Ground water lowering at Minami-Kurihashi in Kuki City, Japan as countermeasure against liquefaction","authors":"Junichi Koseki , Kazue Wakamatsu , Katsuya Matsushita , Tomoaki Yahaba","doi":"10.1016/j.sandf.2025.101597","DOIUrl":"10.1016/j.sandf.2025.101597","url":null,"abstract":"<div><div>Extensive liquefaction took place in Minami-Kurihashi, Kuki City, Saitama, Japan during the 2011 Off the Pacific Coast of Tohoku Earthquake, which induced damage to houses and infrastructures. Based on the results of a detailed geotechnical investigation, the ground water lowering method has been adopted and executed as a countermeasure against liquefaction. This report summarizes how this countermeasure could be implemented, including the results from field monitoring and relevant analyses of the local ground water level and surface settlement that were conducted during and after the ground water lowering. By newly installing a network of drainage ditches, cut-off sheet pile walls, and operating manhole pumps, it was possible to lower the ground water level in order to prevent/reduce future liquefaction damage. In the non-execution areas outside the cut-off walls, the ground water level was not affected by this operation. As of the end of the monitoring period, the measured maximum settlement and tilting ratio were 36 mm and 1.03/1000, respectively. All the monitoring data satisfied the pre-assigned control limits of 40 mm and 2/1000, respectively. In order to numerically simulate the monitored behavior, modification of the compression index and coefficient of permeability was required. Based on the results of a long-term behavior analysis using the modified parameters, the final settlement and tilting ratio were predicted to be, at maximum, 54 mm and 1.50/1000, respectively. The latter value satisfied the pre-assigned threshold limit of 3/1000.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 3","pages":"Article 101597"},"PeriodicalIF":3.3,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143644395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-12DOI: 10.1016/j.sandf.2025.101590
Itsuki Sato , Reiko Kuwano , Masahide Otsubo
Crushable porous soils, such as volcanic pumice, are distributed worldwide and cause a variety of engineering problems, such as slope hazards. The mechanical properties of these soils are complicated by their high compressibility due to voids in the particles themselves and changes in the soil gradation due to particle crushing. They are usually classified as problematic soils and discussed separately from ordinary granular soils, and their behaviour is not systematically understood. In this study, isotropic and triaxial compression tests were conducted on artificial pumice in order to determine the relationship between the mechanical properties and the particle crushing of crushable porous granular materials. The results showed that the mechanical behaviour of artificial pumice, representative of such materials, can be explained using a particle crushing index, which is related to the degree of efficient packing. Furthermore, a new critical state surface equation was proposed. It is applicable to crushable porous granular materials and shows the potential for expressing the critical state or isotropic consolidation state of such materials as a single surface in a three-dimensional space consisting of three axes: the stress − void ratio − crushing index. The validity of this new equation was confirmed by applying it to natural pumice from previous research.
{"title":"Particle crushing and critical state surface of porous granular materials derived from artificial pumice","authors":"Itsuki Sato , Reiko Kuwano , Masahide Otsubo","doi":"10.1016/j.sandf.2025.101590","DOIUrl":"10.1016/j.sandf.2025.101590","url":null,"abstract":"<div><div>Crushable porous soils, such as volcanic pumice, are distributed worldwide and cause a variety of engineering problems, such as slope hazards. The mechanical properties of these soils are complicated by their high compressibility due to voids in the particles themselves and changes in the soil gradation due to particle crushing. They are usually classified as problematic soils and discussed separately from ordinary granular soils, and their behaviour is not systematically understood. In this study, isotropic and triaxial compression tests were conducted on artificial pumice in order to determine the relationship between the mechanical properties and the particle crushing of crushable porous granular materials. The results showed that the mechanical behaviour of artificial pumice, representative of such materials, can be explained using a particle crushing index, which is related to the degree of efficient packing. Furthermore, a new critical state surface equation was proposed. It is applicable to crushable porous granular materials and shows the potential for expressing the critical state or isotropic consolidation state of such materials as a single surface in a three-dimensional space consisting of three axes: the stress − void ratio − crushing index. The validity of this new equation was confirmed by applying it to natural pumice from previous research.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 3","pages":"Article 101590"},"PeriodicalIF":3.3,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143609227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-12DOI: 10.1016/j.sandf.2025.101598
Yang Bai , Qin Chao , Yang Yuan-hao , Cheng Feng , Zhao Shan-shan
Based on the field ultimate load test, the uplift bearing characteristics of reinforced cement concrete (RCC) bored piles in clay and sandstone strata were analyzed, and semi empirical methods for calculating the ultimate uplift capacity of rock socketed pile were proposed. This method was compared with the design codes of pile foundations in China and Europe, and its reliability was verified by engineering case analysis. The results show that the relationship curves between pile top displacement and uplift load are of steep deformation type. In the field test, the ultimate uplift capacity increases with the increase of rock socketed depth or pile diameter. The failure mode of uplift pile is the relative sliding failure of pile body and surrounding rock and soil. In this technical report, the relationship between ultimate side resistance and unconfined compressive strength of sandstone is proposed, (MPa). And the calculation method of ultimate uplift capacity of the pile in clay and sandstone strata is proposed. The calculated results are in good agreement with the test results, with an error of −11.4 % to 9.5 %, which is smaller than that of the design codes of pile foundations in China and Europe. This calculated method has a certain reference for the design of uplift piles in similar strata.
{"title":"Field test study on uplift bearing characteristics of rock socketed piles in sandstone stratum","authors":"Yang Bai , Qin Chao , Yang Yuan-hao , Cheng Feng , Zhao Shan-shan","doi":"10.1016/j.sandf.2025.101598","DOIUrl":"10.1016/j.sandf.2025.101598","url":null,"abstract":"<div><div>Based on the field ultimate load test, the uplift bearing characteristics of reinforced cement concrete (RCC) bored piles in clay and sandstone strata were analyzed, and semi empirical methods for calculating the ultimate uplift capacity of rock socketed pile were proposed. This method was compared with the design codes of pile foundations in China and Europe, and its reliability was verified by engineering case analysis. The results show that the relationship curves between pile top displacement and uplift load are of steep deformation type. In the field test, the ultimate uplift capacity increases with the increase of rock socketed depth or pile diameter. The failure mode of uplift pile is the relative sliding failure of pile body and surrounding rock and soil. In this technical report, the relationship between ultimate side resistance <span><math><mrow><msub><mi>f</mi><mi>r</mi></msub></mrow></math></span> and unconfined compressive strength <span><math><mrow><msub><mi>σ</mi><mi>c</mi></msub></mrow></math></span> of sandstone is proposed,<span><math><mrow><msub><mi>f</mi><mi>r</mi></msub><mo>=</mo><mn>0.18</mn><msubsup><mi>σ</mi><mi>c</mi><mrow><mn>0.5</mn></mrow></msubsup></mrow></math></span> (MPa). And the calculation method of ultimate uplift capacity of the pile in clay and sandstone strata is proposed. The calculated results are in good agreement with the test results, with an error of −11.4 % to 9.5 %, which is smaller than that of the design codes of pile foundations in China and Europe. This calculated method has a certain reference for the design of uplift piles in similar strata.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 3","pages":"Article 101598"},"PeriodicalIF":3.3,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143609228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shake table tests on a levee deteriorated by seepage-induced internal erosion are performed in a geotechnical centrifuge to investigate the effects of erosion-induced heterogeneity and mechanical characteristics change on the seismic response of the levee. Among the several forms of internal erosion, suffusion, in which the seepage-induced loss of soil integrity occurs with the migration and loss of finer particles, is the focus of this study, since it progresses and puts structures in danger, while going unnoticed. In the tests, the model levee made of gap-graded soil is firstly subjected to repeated seepage flow by changing the water level in the flood channel. After lowering the water level and making the levee dry, earthquake motions are applied to the model deteriorated by suffusion. The progression of suffusion in the levee is confirmed by comparing the results of tests having the same initial condition, but subjected to a different number of seepage cycles. The shake table tests reveal that the natural frequency of the levee and the equivalent shear wave velocity in the levee significantly decrease with suffusion, suggesting that a reduction in soil stiffness occurs due to suffusion. However, no significant difference can be confirmed in the earthquake-induced crest settlement depending on the seepage cycles, suggesting that no marked change in strength or cyclic-shearing-induced compression occurs with suffusion within the scope of this study.
{"title":"Centrifuge model tests on suffusion-induced deterioration and its consequences in seismic response of levees","authors":"Akihiro Takahashi , Tamaki Inoue , Saki Yamagata , Kazuki Horikoshi","doi":"10.1016/j.sandf.2025.101592","DOIUrl":"10.1016/j.sandf.2025.101592","url":null,"abstract":"<div><div>Shake table tests on a levee deteriorated by seepage-induced internal erosion are performed in a geotechnical centrifuge to investigate the effects of erosion-induced heterogeneity and mechanical characteristics change on the seismic response of the levee. Among the several forms of internal erosion, suffusion, in which the seepage-induced loss of soil integrity occurs with the migration and loss of finer particles, is the focus of this study, since it progresses and puts structures in danger, while going unnoticed. In the tests, the model levee made of gap-graded soil is firstly subjected to repeated seepage flow by changing the water level in the flood channel. After lowering the water level and making the levee dry, earthquake motions are applied to the model deteriorated by suffusion. The progression of suffusion in the levee is confirmed by comparing the results of tests having the same initial condition, but subjected to a different number of seepage cycles. The shake table tests reveal that the natural frequency of the levee and the equivalent shear wave velocity in the levee significantly decrease with suffusion, suggesting that a reduction in soil stiffness occurs due to suffusion. However, no significant difference can be confirmed in the earthquake-induced crest settlement depending on the seepage cycles, suggesting that no marked change in strength or cyclic-shearing-induced compression occurs with suffusion within the scope of this study.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 2","pages":"Article 101592"},"PeriodicalIF":3.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143511678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Around the world severe damages were observed due to reliquefaction during repeated earthquakes, whereas precise understanding of its mesoscopic mechanism is not much discovered. Influence of these earthquakes on reliquefaction needs to be investigated to understand its significance in contributing to inherent sand resistance. In the present study, centrifuge model experiments were performed to examine the influence of foreshocks/aftershocks and mainshock sequence on resistance to reliquefaction. Two different shaking sequences comprising six shaking events were experimented with Toyoura sand specimen with 50 % relative density. Acceleration amplitude and shaking duration of a mainshock is twice that of foreshock/aftershock. In-house developed advanced digital image processing (DIP) technology was used to estimate mesoscopic characteristics from the images captured during the experiment. The responses were recorded in the form of acceleration, excess pore pressure (EPP), subsidence, induced sand densification, cyclic stress ratio, void ratio and average coordination number. Presence of foreshocks slightly increased the resistance against EPP before it gets completely liquefied during the mainshock. Similarly, aftershocks also regained the resistance of liquefied soil due to reorientation of particles and limited generation of EPP. However, application of mainshocks triggered liquefaction and reliquefaction and thus eliminated the beneficial effects achieved from the prior foreshocks. Reliquefaction was observed to be more damaging than the first liquefaction, meanwhile the induced sand densification from repeated shakings did not contribute to increased resistance to reliquefaction. The apparent void ratio estimated from the DIP technology was in good agreement with real void ratio values. Average coordination number indicated that the sand particles moved closer to each other which resulted in increased resistance during foreshocks/aftershocks. In contrast, complete liquefaction and reliquefaction have destroyed the dense soil particle interlocking and made specimen more vulnerable to higher EPP generation.
{"title":"Mesoscopic mechanism behind the inherent reliquefaction resistance subjected to repeated earthquakes using centrifuge modelling and advanced digital image processing","authors":"Gowtham Padmanabhan , Bal Krishna Maheshwari , Kyohei Ueda , Ryosuke Uzuoka","doi":"10.1016/j.sandf.2025.101589","DOIUrl":"10.1016/j.sandf.2025.101589","url":null,"abstract":"<div><div>Around the world severe damages were observed due to reliquefaction during repeated earthquakes, whereas precise understanding of its mesoscopic mechanism is not much discovered. Influence of these earthquakes on reliquefaction needs to be investigated to understand its significance in contributing to inherent sand resistance. In the present study, centrifuge model experiments were performed to examine the influence of foreshocks/aftershocks and mainshock sequence on resistance to reliquefaction. Two different shaking sequences comprising six shaking events were experimented with Toyoura sand specimen with 50 % relative density. Acceleration amplitude and shaking duration of a mainshock is twice that of foreshock/aftershock. In-house developed advanced digital image processing (DIP) technology was used to estimate mesoscopic characteristics from the images captured during the experiment. The responses were recorded in the form of acceleration, excess pore pressure (EPP), subsidence, induced sand densification, cyclic stress ratio, void ratio and average coordination number. Presence of foreshocks slightly increased the resistance against EPP before it gets completely liquefied during the mainshock. Similarly, aftershocks also regained the resistance of liquefied soil due to reorientation of particles and limited generation of EPP. However, application of mainshocks triggered liquefaction and reliquefaction and thus eliminated the beneficial effects achieved from the prior foreshocks. Reliquefaction was observed to be more damaging than the first liquefaction, meanwhile the induced sand densification from repeated shakings did not contribute to increased resistance to reliquefaction. The apparent void ratio estimated from the DIP technology was in good agreement with real void ratio values. Average coordination number indicated that the sand particles moved closer to each other which resulted in increased resistance during foreshocks/aftershocks. In contrast, complete liquefaction and reliquefaction have destroyed the dense soil particle interlocking and made specimen more vulnerable to higher EPP generation.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 2","pages":"Article 101589"},"PeriodicalIF":3.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143509193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.sandf.2025.101591
Mitsu Okamura , Nene Kusube
The hydraulic gradient that causes backward erosion piping in river levees is of significant concern in geotechnical engineering. Traditionally, the mechanism of pipe progression beneath levees has primarily been studied using small-scale model experiments. Prediction methods for the critical hydraulic gradient have been developed in which the simple pipe geometry and laminar pipe flow were assumed. However, recent studies have suggested that turbulent flow is more likely in the pipes of prototype-scale levees and that both the pipe geometry and flow regime significantly influence pipe progression and the resulting gradient. The present study proposes a prediction method that accounts for the effects of the foundation’s soil properties, levee scale, flow regime, and pipe geometry. The method is validated by comparing the predicted results with those from centrifuge tests. All the analytical results are found to be consistent with the test observations, demonstrating that the proposed method can satisfactorily predict the effects of the testing parameters on the hydraulic gradient. The scale effect of levees on the critical hydraulic gradient remains a critical issue, as the direct application of small-scale test results to prototype levees often results in the overprediction of the gradient. The method is also used to evaluate the progression gradient of full-scale levees, confirming that the gradient is inversely proportional to the square root of the levee width (L−1/2) under laminar pipe flow conditions. Under turbulent flow conditions, which are more likely in field-scale levees, the exponent may be even smaller.
{"title":"Prediction of hydraulic gradient for backward erosion piping in river levees considering flow regime and pipe geometry","authors":"Mitsu Okamura , Nene Kusube","doi":"10.1016/j.sandf.2025.101591","DOIUrl":"10.1016/j.sandf.2025.101591","url":null,"abstract":"<div><div>The hydraulic gradient that causes backward erosion piping in river levees is of significant concern in geotechnical engineering. Traditionally, the mechanism of pipe progression beneath levees has primarily been studied using small-scale model experiments. Prediction methods for the critical hydraulic gradient have been developed in which the simple pipe geometry and laminar pipe flow were assumed. However, recent studies have suggested that turbulent flow is more likely in the pipes of prototype-scale levees and that both the pipe geometry and flow regime significantly influence pipe progression and the resulting gradient. The present study proposes a prediction method that accounts for the effects of the foundation’s soil properties, levee scale, flow regime, and pipe geometry. The method is validated by comparing the predicted results with those from centrifuge tests. All the analytical results are found to be consistent with the test observations, demonstrating that the proposed method can satisfactorily predict the effects of the testing parameters on the hydraulic gradient. The scale effect of levees on the critical hydraulic gradient remains a critical issue, as the direct application of small-scale test results to prototype levees often results in the overprediction of the gradient. The method is also used to evaluate the progression gradient of full-scale levees, confirming that the gradient is inversely proportional to the square root of the levee width (<em>L</em><sup>−1/2</sup>) under laminar pipe flow conditions. Under turbulent flow conditions, which are more likely in field-scale levees, the exponent may be even smaller.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 2","pages":"Article 101591"},"PeriodicalIF":3.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143511679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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