Pub Date : 2025-07-14DOI: 10.1016/j.sandf.2025.101635
Riccardo Fanni , David Reid , Andy Fourie
Experimental results are presented in this technical paper to investigate the mechanisms of plane strain consolidation and drained shearing typical of below slope conditions. Five torsional shear hollow cylinder tests were conducted on a sandy silt gold tailings, where consolidation was performed under at-rest (K0) conditions, and by applying a horizontal shear stress, while maintaining plane strain conditions. The tests were carried out under drained simple shear conditions (strain controlled) on tailings specimens prepared in loose and dense states and along a constant shear stress drained stress path (stress controlled) on a loose specimen, using an automated computer-controlled testing procedure. The evolution of static stresses in the loose and dense specimens during principal stress rotation, while maintaining plane strain conditions, were examined. These tests provide valuable insights into the behavior of tailings under plane strain conditions, contributing to the calibration of numerical models for slope analysis and more broadly for plane strain problems.
{"title":"Behaviour of a sandy silt gold tailings under drained simple shear loading in a torsional shear hollow cylinder apparatus","authors":"Riccardo Fanni , David Reid , Andy Fourie","doi":"10.1016/j.sandf.2025.101635","DOIUrl":"10.1016/j.sandf.2025.101635","url":null,"abstract":"<div><div>Experimental results are presented in this technical paper to investigate the mechanisms of plane strain consolidation and drained shearing typical of below slope conditions. Five torsional shear hollow cylinder tests were conducted on a sandy silt gold tailings, where consolidation was performed under at-rest (<em>K<sub>0</sub></em>) conditions, and by applying a horizontal shear stress, while maintaining plane strain conditions. The tests were carried out under drained simple shear conditions (strain controlled) on tailings specimens prepared in loose and dense states and along a constant shear stress drained stress path (stress controlled) on a loose specimen, using an automated computer-controlled testing procedure. The evolution of static stresses in the loose and dense specimens during principal stress rotation, while maintaining plane strain conditions, were examined. These tests provide valuable insights into the behavior of tailings under plane strain conditions, contributing to the calibration of numerical models for slope analysis and more broadly for plane strain problems.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 4","pages":"Article 101635"},"PeriodicalIF":3.3,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144614046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-07-14DOI: 10.1016/j.sandf.2025.101652
Daichi Yokoyama , Masahide Otsubo , Reiko Kuwano
Ground cave-ins, which are the collapse and discontinuous subsidence of the ground surface, are thought to be caused by the expansion and upward movement of subsurface cavities due to fluctuations in the groundwater table or earthquakes. Compared to cohesive clays or plastic silts, cohesionless sands are more vulnerable to cavity formation and subsequent ground cave-ins. With recent technology, such as ground-penetrating radar, geometrical information on cavities, e.g., location and shape, can be detected. In practice, the soil cover thickness-to-cavity width ratio () is often used for risk assessments of cave-ins. However, it is questionable whether alone is sufficient for these risk assessments since the mechanical responses, such as the resistance of the remaining soil above the cavity, are not considered. For this reason, the aim of the present contribution is to understand the mechanism underlying the subsurface cavity stability by considering the force transfer around the cavity. Suction measurement, cavity retention, and needle penetration model tests were conducted using various coarse granular materials. The results revealed that suction is essential to preventing cavities from collapsing, and that suction is higher for smaller particles, particles with lower degrees of saturation, and particles with angular shapes and smoother surfaces. In addition to , the mechanical interlock from angularity or roughness contributes to cavity stability. Laboratory needle penetration tests revealed the existence of a force-transfer arch between the sound and weakened zones around a cavity, which is related to the cavity stability. Furthermore, the position of the arch is affected not only by , but also by the particle characteristics (e.g., friction angle) and cavity roof shape. Therefore, considering the material type and the shape of the cavity roof, along with , will lead to enhanced assessments of the cave-in potential of subsurface cavities.
{"title":"Shaping force-transfer arch to retain subsurface cavity in coarse sandy ground","authors":"Daichi Yokoyama , Masahide Otsubo , Reiko Kuwano","doi":"10.1016/j.sandf.2025.101652","DOIUrl":"10.1016/j.sandf.2025.101652","url":null,"abstract":"<div><div>Ground cave-ins, which are the collapse and discontinuous subsidence of the ground surface, are thought to be caused by the expansion and upward movement of subsurface cavities due to fluctuations in the groundwater table or earthquakes. Compared to cohesive clays or plastic silts, cohesionless sands are more vulnerable to cavity formation and subsequent ground cave-ins. With recent technology, such as ground-penetrating radar, geometrical information on cavities, <em>e.g.,</em> location and shape, can be detected. In practice, the soil cover thickness-to-cavity width ratio (<span><math><mrow><mi>H</mi><mo>/</mo><mi>B</mi></mrow></math></span>) is often used for risk assessments of cave-ins. However, it is questionable whether <span><math><mrow><mi>H</mi><mo>/</mo><mi>B</mi></mrow></math></span> alone is sufficient for these risk assessments since the mechanical responses, such as the resistance of the remaining soil above the cavity, are not considered. For this reason, the aim of the present contribution is to understand the mechanism underlying the subsurface cavity stability by considering the force transfer around the cavity. Suction measurement, cavity retention, and needle penetration model tests were conducted using various coarse granular materials. The results revealed that suction is essential to preventing cavities from collapsing, and that suction is higher for smaller particles, particles with lower degrees of saturation, and particles with angular shapes and smoother surfaces. In addition to <span><math><mrow><mi>H</mi><mo>/</mo><mi>B</mi></mrow></math></span>, the mechanical interlock from angularity or roughness contributes to cavity stability. Laboratory needle penetration tests revealed the existence of a force-transfer arch between the sound and weakened zones around a cavity, which is related to the cavity stability. Furthermore, the position of the arch is affected not only by <span><math><mrow><mi>H</mi><mo>/</mo><mi>B</mi></mrow></math></span>, but also by the particle characteristics (<em>e.g.,</em> friction angle) and cavity roof shape. Therefore, considering the material type and the shape of the cavity roof, along with <span><math><mrow><mi>H</mi><mo>/</mo><mi>B</mi></mrow></math></span>, will lead to enhanced assessments of the cave-in potential of subsurface cavities.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 4","pages":"Article 101652"},"PeriodicalIF":3.3,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144614047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-07-07DOI: 10.1016/j.sandf.2025.101651
Joyce Nakayenga , Toshiro Hata , Alexandra Clarà Saracho , Stuart Kenneth Haigh
Sporosarcina newyorkensis is an indigenous microbe found in sedimentary layers bearing methane hydrates in the oceans around Japan’s main islands. It can survive extremely cold temperatures and precipitate calcium carbonate (CaCO3). This has led to interest in applying the microbe in microbiologically induced calcium carbonate precipitation (MICP) to improve the properties of the surrounding sand and to facilitate the exploration of methane hydrates. Using the injection method, a large-scale laboratory experiment was conducted in this study on sand columns with a diameter of 60 cm and a height of 70 cm to evaluate the MICP performance of S. newyorkensis under high overburden pressures of 3.5 and 20 MPa. The results indicated that S. newyorkensis can precipitate CaCO3 at high overburden pressures and reduce the permeability of sand. The unconfined compressive strength and amount of precipitated CaCO3 were seen to decrease with the distance from the injection well, but they remained sufficient to distances of up to 20 cm. S. newyorkensis was also found to increase the pH level, which would further promote CaCO3 precipitation and, in turn, lower hydraulic conductivity and stabilize hydrate-bearing sand formations.
{"title":"Effects of high pressure on microbiologically induced calcium carbonate precipitation of methane hydrate-bearing sand layers","authors":"Joyce Nakayenga , Toshiro Hata , Alexandra Clarà Saracho , Stuart Kenneth Haigh","doi":"10.1016/j.sandf.2025.101651","DOIUrl":"10.1016/j.sandf.2025.101651","url":null,"abstract":"<div><div><em>Sporosarcina newyorkensis</em> is an indigenous microbe found in sedimentary layers bearing methane hydrates in the oceans around Japan’s main islands. It can survive extremely cold temperatures and precipitate calcium carbonate (CaCO<sub>3</sub>). This has led to interest in applying the microbe in microbiologically induced calcium carbonate precipitation (MICP) to improve the properties of the surrounding sand and to facilitate the exploration of methane hydrates. Using the injection method, a large-scale laboratory experiment was conducted in this study on sand columns with a diameter of 60 cm and a height of 70 cm to evaluate the MICP performance of <em>S. newyorkensis</em> under high overburden pressures of 3.5 and 20 MPa. The results indicated that <em>S. newyorkensis</em> can precipitate CaCO<sub>3</sub> at high overburden pressures and reduce the permeability of sand. The unconfined compressive strength and amount of precipitated CaCO<sub>3</sub> were seen to decrease with the distance from the injection well, but they remained sufficient to distances of up to 20 cm. <em>S. newyorkensis</em> was also found to increase the pH level, which would further promote CaCO<sub>3</sub> precipitation and, in turn, lower hydraulic conductivity and stabilize hydrate-bearing sand formations.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 4","pages":"Article 101651"},"PeriodicalIF":3.3,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144571888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-07-03DOI: 10.1016/j.sandf.2025.101600
Taichi Ishimaru , Motoyuki Suzuki , Asahi Komori
Suffusion is the detachment and migration of fine particles through voids connected by the matrices of coarse particles. Although water storage structures are known to be affected by fluctuations in seepage flow, due to fluctuations in the water storage levels brought about by rainfall and agricultural activities, the suffusion behavior when the hydraulic gradient is fluctuated is unclear. In this study, one-dimensional downward water-passing experiments with suffusion were performed using a cylindrical column device, and the changes in the amounts of the discharged water and soil particles, as well as the turbidity of the drainage over time, were examined. The behavior of suffusion was investigated from two viewpoints: the quantitative changes in the amount of discharged drainage and the amount of discharged soil particles due to the progress of suffusion, and the qualitative changes in the particle size composition of the discharged soil particles. A unique feature of this study was the tracing of the changes in the particle size composition of the discharged soil particles from the relationship between the turbidity and the concentration of drainage during suffusion. As a result, it was found that not only the amount of soil particles discharged by suffusion, but also the particle size composition of the discharged soil particles changed under both constant and fluctuated hydraulic gradient conditions.
{"title":"Suffusion behavior under fluctuated hydraulic gradient conditions focusing on amount and size of soil particles contained in drainage","authors":"Taichi Ishimaru , Motoyuki Suzuki , Asahi Komori","doi":"10.1016/j.sandf.2025.101600","DOIUrl":"10.1016/j.sandf.2025.101600","url":null,"abstract":"<div><div>Suffusion is the detachment and migration of fine particles through voids connected by the matrices of coarse particles. Although water storage structures are known to be affected by fluctuations in seepage flow, due to fluctuations in the water storage levels brought about by rainfall and agricultural activities, the suffusion behavior when the hydraulic gradient is fluctuated is unclear. In this study, one-dimensional downward water-passing experiments with suffusion were performed using a cylindrical column device, and the changes in the amounts of the discharged water and soil particles, as well as the turbidity of the drainage over time, were examined. The behavior of suffusion was investigated from two viewpoints: the quantitative changes in the amount of discharged drainage and the amount of discharged soil particles due to the progress of suffusion, and the qualitative changes in the particle size composition of the discharged soil particles. A unique feature of this study was the tracing of the changes in the particle size composition of the discharged soil particles from the relationship between the turbidity and the concentration of drainage during suffusion. As a result, it was found that not only the amount of soil particles discharged by suffusion, but also the particle size composition of the discharged soil particles changed under both constant and fluctuated hydraulic gradient conditions.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 4","pages":"Article 101600"},"PeriodicalIF":3.3,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144549030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-07-03DOI: 10.1016/j.sandf.2025.101602
Tingting Deng , Yongfeng Deng , Hang Liu , Fang Liu , Zhenshun Hong , Xueyu Geng
Solidification/stabilization of heavy metal contaminated soils often falls short of achieving the desired quality due to challenges in effectively controlling mixing uniformity. Optimization of mixing equipment and construction technology is a common way to improve mixing uniformity. However, optimizing mixing equipment has high cost, limited site applicability and limited effect on improving uniformity. To solve the problem, a combined solidification/stabilization - vacuum dewatering technique (SSVD) was proposed, which is to increase the water to binder ratio to make the binder and heavy metal contaminated soils mixed evenly and then immediately vacuum dewatering. Its efficiency was explored through both laboratory experiments and a pilot project. Because zinc is a well-known factor that decreases compressive strength and cementation speed, zinc contaminated soil was studied. The findings indicate that the vacuum dewatering successfully removes water from solidified soils during the initial 12 h of setting and hardening in the field, indicating the feasibility of more water incorporation to raise the mixing workability. Furthermore, it can enhance the microstructure to prevent the migration of pollutant, and extract the heavy metals from the solidified mass by the cation exchanges. After 28 days of curing, laboratory tests showed a 1.9-4.1 times’ increment in strength and a 1.7-17.8 times’ reduction in permeability after dewatering. In the field, these values increase by 1.8 times and decrease by 1.7 times, respectively. The Zn2+ observed diffusivity also decreases by 2.0 times after dewatering in the laboratory. Microstructure analysis reveals that the vacuum dewatering significantly reduces the porosity of the solidified matrix, thereby enhancing its integrity. The proposed technology holds potential for the application not only in the solidification/stabilization remediation but also in the soft ground improvement in term of the better workability and homogeneity, stronger densification and capsulation, and less pollutant retention and binder consumption.
{"title":"Integrated remediation through solidification and dewatering of contaminated soil from laboratory investigation to in-situ application","authors":"Tingting Deng , Yongfeng Deng , Hang Liu , Fang Liu , Zhenshun Hong , Xueyu Geng","doi":"10.1016/j.sandf.2025.101602","DOIUrl":"10.1016/j.sandf.2025.101602","url":null,"abstract":"<div><div>Solidification/stabilization of heavy metal contaminated soils often falls short of achieving the desired quality due to challenges in effectively controlling mixing uniformity. Optimization of mixing equipment and construction technology is a common way to improve mixing uniformity. However, optimizing mixing equipment has high cost, limited site applicability and limited effect on improving uniformity. To solve the problem, a combined solidification/stabilization - vacuum dewatering technique (SSVD) was proposed, which is to increase the water to binder ratio to make the binder and heavy metal contaminated soils mixed evenly and then immediately vacuum dewatering. Its efficiency was explored through both laboratory experiments and a pilot project. Because zinc is a well-known factor that decreases compressive strength and cementation speed, zinc contaminated soil was studied. The findings indicate that the vacuum dewatering successfully removes water from solidified soils during the initial 12 h of setting and hardening in the field, indicating the feasibility of more water incorporation to raise the mixing workability. Furthermore, it can enhance the microstructure to prevent the migration of pollutant, and extract the heavy metals from the solidified mass by the cation exchanges. After 28 days of curing, laboratory tests showed a 1.9-4.1 times’ increment in strength and a 1.7-17.8 times’ reduction in permeability after dewatering. In the field, these values increase by 1.8 times and decrease by 1.7 times, respectively. The Zn<sup>2+</sup> observed diffusivity also decreases by 2.0 times after dewatering in the laboratory. Microstructure analysis reveals that the vacuum dewatering significantly reduces the porosity of the solidified matrix, thereby enhancing its integrity. The proposed technology holds potential for the application not only in the solidification/stabilization remediation but also in the soft ground improvement in term of the better workability and homogeneity, stronger densification and capsulation, and less pollutant retention and binder consumption.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 4","pages":"Article 101602"},"PeriodicalIF":3.3,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144549031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-07-03DOI: 10.1016/j.sandf.2025.101599
Fumio Tatsuoka , Hervé Di Benedetto
Various trends in rate-dependent stress–strain behaviour caused by the viscous properties of a wide variety of unbound geomaterials that were observed under drained triaxial compression, plane strain compression, direct shear, and one-dimensional compression (i.e., oedometer testing) are summarized referring to those of bound geomaterials and others. The following findings are shown. As the interparticle contact points become more stable and the stability of the particles against rotation increases, the viscous properties become closer to the traditional type, namely, Isotach, whose stress–strain behaviour is determined by the instantaneous irreversible strain rate and whose strength during monotonic loading (ML) at a constant strain rate increases with an increase in the strain rate. A couple of non-traditional (i.e., non-Isotach) types of properties were found with granular materials (GMs) that exhibit noticeable creep deformation, stress relaxation, and changes in stress upon changes in the strain rate. Unbound poorly graded sub-angular to angular GMs exhibit the so-called TESRA type of properties (also called the viscous evanescent type), for which the stress–strain behaviour during ML at a constant strain rate is essentially independent of the strain rate. Unbound poorly graded sub-round to round GMs display the so-called Positive and Negative (P&N) type of properties, for which the strength during ML at a constant strain rate decreases with an increase in the strain rate. The combined type displays intermediate behaviour combining the Isotach and TESRA types of properties. These types of viscous properties are quantitatively characterized by a couple of functions and parameters, and they were incorporated into the non-linear three-component (NTC) model. All the observed trends in rate-dependent stress–strain behaviour are well simulated by the NTC model.
在排水三轴压缩、平面应变压缩、直接剪切和一维压缩（即测径仪测试）下观察到的各种非粘结性岩土材料的粘性特性所引起的速率依赖的应力-应变行为的各种趋势，总结了粘结性岩土材料和其他岩土材料的趋势。结果如下。随着颗粒间接触点的稳定和颗粒抗旋转稳定性的提高，黏性更接近于传统的等压型，即等压型，其应力-应变行为由瞬时不可逆应变速率决定，在恒定应变速率下单调加载（ML）时的强度随着应变速率的增加而增加。在颗粒材料（GMs）中发现了一些非传统（即非等压）类型的性能，它们表现出明显的蠕变、应力松弛和应变速率变化时应力的变化。未结合的差梯度亚角到角GMs表现出所谓的TESRA类型性质（也称为粘性消失类型），其中恒定应变速率下ML期间的应力-应变行为基本上与应变速率无关。未结合的分级差的次圆到圆gm表现出所谓的Positive and Negative （P&；N）型性能，在恒定应变速率下，ML期间的强度随着应变速率的增加而降低。组合类型显示结合了Isotach和TESRA属性类型的中间行为。这些类型的粘性特性通过几个函数和参数进行定量表征，并将其纳入非线性三分量（NTC）模型。NTC模型很好地模拟了所有观察到的速率相关应力-应变行为趋势。
{"title":"Experiment, modelling, and simulation of rate-dependent stress–strain behaviour of unbound geomaterials","authors":"Fumio Tatsuoka , Hervé Di Benedetto","doi":"10.1016/j.sandf.2025.101599","DOIUrl":"10.1016/j.sandf.2025.101599","url":null,"abstract":"<div><div>Various trends in rate-dependent stress–strain behaviour caused by the viscous properties of a wide variety of unbound geomaterials that were observed under drained triaxial compression, plane strain compression, direct shear, and one-dimensional compression (i.e., oedometer testing) are summarized referring to those of bound geomaterials and others. The following findings are shown. As the interparticle contact points become more stable and the stability of the particles against rotation increases, the viscous properties become closer to the traditional type, namely, Isotach, whose stress–strain behaviour is determined by the instantaneous irreversible strain rate and whose strength during monotonic loading (ML) at a constant strain rate increases with an increase in the strain rate. A couple of non-traditional (i.e., non<em>-</em>Isotach) types of properties were found with granular materials (GMs) that exhibit noticeable creep deformation, stress relaxation, and changes in stress upon changes in the strain rate. Unbound poorly graded sub-angular to angular GMs exhibit the so-called TESRA type of properties (also called the viscous evanescent type), for which the stress–strain behaviour during ML at a constant strain rate is essentially independent of the strain rate. Unbound poorly graded sub-round to round GMs display the so-called Positive and Negative (P&N) type of properties, for which the strength during ML at a constant strain rate decreases with an increase in the strain rate. The combined type displays intermediate behaviour combining the Isotach and TESRA types of properties. These types of viscous properties are quantitatively characterized by a couple of functions and parameters, and they were incorporated into the non-linear three-component (NTC) model. All the observed trends in rate-dependent stress–strain behaviour are well simulated by the NTC model.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 4","pages":"Article 101599"},"PeriodicalIF":3.3,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144549029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-07-02DOI: 10.1016/j.sandf.2025.101650
Der-Wen Chang , Shih-Hao Cheng , Wei-Cheng Zheng , Chan-Yen Tseng , Louis Ge
This study investigated the serviceability performance of piled raft foundations (or combined pile-raft foundations, CPRF) in various soils using three-dimensional (3D) finite element analysis. The piled raft foundation was assumed to be embedded respectively in homogeneous clayey soils and sandy soils under vertical loading. The displacements and reactions of the piles were carefully observed. In comparing the influences of soil stiffness, raft width, pile-to-pile spacing distance, and pile length, it was found that the embedment depth of the foundation could significantly affect the serviceability of the piles. For embedment depths ranging from 0 m to 12 m, the pile loads can be reduced by approximately 40 % to 60 % of the foundation load, depending on the number of piles involved. The displacements of piled raft foundations in clays decrease with increased embedment depth. However, the effects of embedment depth on foundation displacements are smaller in sands. Furthermore, the load ratio of the piles and the displacement ratio of the CPRF were calculated to demonstrate their dependence on the slenderness ratio of the piles and the number of piles. Both ratios aligned with the guidelines the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE) proposed for CPRF systems. Notably, attention is drawn to the depth of raft embedment, as it significantly influences pile responses.
{"title":"Serviceability performance of piled raft foundations under vertical loads in clayey and sandy soils","authors":"Der-Wen Chang , Shih-Hao Cheng , Wei-Cheng Zheng , Chan-Yen Tseng , Louis Ge","doi":"10.1016/j.sandf.2025.101650","DOIUrl":"10.1016/j.sandf.2025.101650","url":null,"abstract":"<div><div>This study investigated the serviceability performance of piled raft foundations (or combined pile-raft foundations, CPRF) in various soils using three-dimensional (3D) finite element analysis. The piled raft foundation was assumed to be embedded respectively in homogeneous clayey soils and sandy soils under vertical loading. The displacements and reactions of the piles were carefully observed. In comparing the influences of soil stiffness, raft width, pile-to-pile spacing distance, and pile length, it was found that the embedment depth of the foundation could significantly affect the serviceability of the piles. For embedment depths ranging from 0 m to 12 m, the pile loads can be reduced by approximately 40 % to 60 % of the foundation load, depending on the number of piles involved. The displacements of piled raft foundations in clays decrease with increased embedment depth. However, the effects of embedment depth on foundation displacements are smaller in sands. Furthermore, the load ratio of the piles and the displacement ratio of the CPRF were calculated to demonstrate their dependence on the slenderness ratio of the piles and the number of piles. Both ratios aligned with the guidelines the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE) proposed for CPRF systems. Notably, attention is drawn to the depth of raft embedment, as it significantly influences pile responses.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 4","pages":"Article 101650"},"PeriodicalIF":3.3,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144522055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-06-30DOI: 10.1016/j.sandf.2025.101649
Luigi Pugliese, Antonello Troncone, Andrea Parise, Enrico Conte
Prediction of the earthquake-induced permanent displacements of retaining structures is a key step in the context of a performance-based design approach. For retaining walls with shallow foundations, this issue is usually dealt with using the well-known Newmark sliding block method. However, several studies have shown that this method is unsuitable to provide a trustworthy prediction of the permanent displacements undergone by the embedded cantilever retaining walls under seismic loading. To overcome this drawback, a new method of practical interest is proposed in the present study for a prediction of the earthquake-induced permanent displacement of these structures. In such a method, the wall movements are evaluated solving a simple equation of motion whenever the ground acceleration exceeds a critical value. This latter value is updated during the seismic event by calculating the forces acting on the wall by means of a closed form solution recently derived by the authors. The method is simple to use and requires few conventional parameters as input data. These features make it suitable for current applications. To assess the predictive capability of the present method, comparisons with the results of a centrifuge test documented in the literature and with those of a large number of ideal case studies solved using a finite element code, are presented. The effectiveness of some measures to reduce the wall displacements is also discussed.
{"title":"An approach for predicting earthquake-induced permanent displacements of embedded cantilever walls in soils with cohesion","authors":"Luigi Pugliese, Antonello Troncone, Andrea Parise, Enrico Conte","doi":"10.1016/j.sandf.2025.101649","DOIUrl":"10.1016/j.sandf.2025.101649","url":null,"abstract":"<div><div>Prediction of the earthquake-induced permanent displacements of retaining structures is a key step in the context of a performance-based design approach. For retaining walls with shallow foundations, this issue is usually dealt with using the well-known Newmark sliding block method. However, several studies have shown that this method is unsuitable to provide a trustworthy prediction of the permanent displacements undergone by the embedded cantilever retaining walls under seismic loading. To overcome this drawback, a new method of practical interest is proposed in the present study for a prediction of the earthquake-induced permanent displacement of these structures. In such a method, the wall movements are evaluated solving a simple equation of motion whenever the ground acceleration exceeds a critical value. This latter value is updated during the seismic event by calculating the forces acting on the wall by means of a closed form solution recently derived by the authors. The method is simple to use and requires few conventional parameters as input data. These features make it suitable for current applications. To assess the predictive capability of the present method, comparisons with the results of a centrifuge test documented in the literature and with those of a large number of ideal case studies solved using a finite element code, are presented. The effectiveness of some measures to reduce the wall displacements is also discussed.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 4","pages":"Article 101649"},"PeriodicalIF":3.3,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144518750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-06-26DOI: 10.1016/j.sandf.2025.101648
Changhui Gao , Songyu Liu , Guangyin Du , Mei Bai , Yankai Wu , Runmin Hao
This study aims to investigate the permeation mechanisms and pressure distribution of gas jets in collapsible loess during pneumatic-vibratory probe compaction (PVPC). Indoor model tests were performed to analyze the behavior of continuous gas jet injection, and a seepage pressure distribution model was developed to characterize gas flow in unsaturated loess. The results show that pulsating gas jets disrupt the soil structure near the nozzle, enabling gas penetration driven by internal pressure differentials and leading to the gradual formation of continuous fractures. Gas pressure measurements at the opposite end of the soil layer indicate an initial pressure rise that stabilizes over time, with thinner soil layers showing more pronounced responses. The proposed model effectively captures the dynamic behavior of gas flow, illustrating a rapid decline in seepage pressure over time and a slow increase in seepage distance. These findings enhance the understanding of gas jet permeation and provide practical guidance for optimizing PVPC parameters, further advancing its application in loess foundation improvement within geotechnical engineering.
{"title":"Seepage pressure distribution of gas jet flow in loess","authors":"Changhui Gao , Songyu Liu , Guangyin Du , Mei Bai , Yankai Wu , Runmin Hao","doi":"10.1016/j.sandf.2025.101648","DOIUrl":"10.1016/j.sandf.2025.101648","url":null,"abstract":"<div><div>This study aims to investigate the permeation mechanisms and pressure distribution of gas jets in collapsible loess during pneumatic-vibratory probe compaction (PVPC). Indoor model tests were performed to analyze the behavior of continuous gas jet injection, and a seepage pressure distribution model was developed to characterize gas flow in unsaturated loess. The results show that pulsating gas jets disrupt the soil structure near the nozzle, enabling gas penetration driven by internal pressure differentials and leading to the gradual formation of continuous fractures. Gas pressure measurements at the opposite end of the soil layer indicate an initial pressure rise that stabilizes over time, with thinner soil layers showing more pronounced responses. The proposed model effectively captures the dynamic behavior of gas flow, illustrating a rapid decline in seepage pressure over time and a slow increase in seepage distance. These findings enhance the understanding of gas jet permeation and provide practical guidance for optimizing PVPC parameters, further advancing its application in loess foundation improvement within geotechnical engineering.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 4","pages":"Article 101648"},"PeriodicalIF":3.3,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144481271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-06-26DOI: 10.1016/j.sandf.2025.101647
Tao Zhang , Yufeng Shi , Shuying Wang , Menghao Hu , Sijin He
When shield tunnels traverse the upper-soft and lower-hard stratum, the pronounced geological differences lead to uneven stress distribution on the segmental lining, thereby intensifying both construction challenges and safety risks. Investigating the loading conditions and mechanical characteristics of tunnel linings in such strata is imperative. Therefore, field measurements were conducted at two shield tunnel construction sites along Nanchang Metro Line 1, specifically within a silty clay-gravel layer and a homogeneous sand layer. The acting load and internal forces of the segmental lining were monitored over an extended period. By analyzing the monitoring data, the variation patterns of the loads acting on the segmental lining in the upper-soft and lower-hard stratum during the construction stage were summarized. Furthermore, a comparative analysis was carried out between the measured loading conditions and the theoretical analytical solutions. Subsequently, a refined numerical simulation incorporating bolt joints and bolt preload on the segment was performed to further explore the mechanical behavior of the segmental lining, with a comparison to the measured internal force data. The results indicate that synchronous grouting at the shield tail significantly affects the earth pressure in the upper soft soil layer, with the maximum earth pressure induced by synchronous grouting being approximately 1.9 times the final stable value. The vertical earth pressure in the upper part of the segmental lining exhibits a characteristic pattern of being “large in the middle and small at both ends”, with the measured maximum value after stabilization corresponding to approximately 72% of the theoretical value predicted by Terzaghi’s theory. Notably, a sudden change in lateral earth pressure is observed at the stratum interface. The bending moment and axial force at the invert of the tunnel segment are comparatively smaller than those at the vault. Additionally, the development of internal forces within the segment is fairly constrained in the lower hard stratum.
{"title":"Investigation of acting load and mechanical characteristics of shield tunnel lining in upper-soft and lower-hard stratum","authors":"Tao Zhang , Yufeng Shi , Shuying Wang , Menghao Hu , Sijin He","doi":"10.1016/j.sandf.2025.101647","DOIUrl":"10.1016/j.sandf.2025.101647","url":null,"abstract":"<div><div>When shield tunnels traverse the upper-soft and lower-hard stratum, the pronounced geological differences lead to uneven stress distribution on the segmental lining, thereby intensifying both construction challenges and safety risks. Investigating the loading conditions and mechanical characteristics of tunnel linings in such strata is imperative. Therefore, field measurements were conducted at two shield tunnel construction sites along Nanchang Metro Line 1, specifically within a silty clay-gravel layer and a homogeneous sand layer. The acting load and internal forces of the segmental lining were monitored over an extended period. By analyzing the monitoring data, the variation patterns of the loads acting on the segmental lining in the upper-soft and lower-hard stratum during the construction stage were summarized. Furthermore, a comparative analysis was carried out between the measured loading conditions and the theoretical analytical solutions. Subsequently, a refined numerical simulation incorporating bolt joints and bolt preload on the segment was performed to further explore the mechanical behavior of the segmental lining, with a comparison to the measured internal force data. The results indicate that synchronous grouting at the shield tail significantly affects the earth pressure in the upper soft soil layer, with the maximum earth pressure induced by synchronous grouting being approximately 1.9 times the final stable value. The vertical earth pressure in the upper part of the segmental lining exhibits a characteristic pattern of being “large in the middle and small at both ends”, with the measured maximum value after stabilization corresponding to approximately 72% of the theoretical value predicted by Terzaghi’s theory. Notably, a sudden change in lateral earth pressure is observed at the stratum interface. The bending moment and axial force at the invert of the tunnel segment are comparatively smaller than those at the vault. Additionally, the development of internal forces within the segment is fairly constrained in the lower hard stratum.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 4","pages":"Article 101647"},"PeriodicalIF":3.3,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144481272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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