Pub Date : 2025-02-01DOI: 10.1016/j.sandf.2024.101562
Peng Liu , Yu Cheng , Guanghui Shao
To improve the reinforcement effect of MICP technology on fine-grained soil, and consider the fine particle size and activity characteristics of red mud, the experiment of red mud strengthening MICP solidified fine-grained soil was designed and carried out. Combined with mechanical test and microstructural analysis, the enhancing mechanism of red mud on microbial solidified fine-grained soil was comprehensively evaluated. The results show that: (1) Red mud can significantly improve the production of cement during microbial reinforcement of fine-grained soils; the optimal dosage of red mud is 20 %, which increases the strength by 34.6 % and the production of cement by 42.9 %, compared with conventional MICP. (2) After red mud was incorporated into the soil, the pore volume and pore diameter of the treated soil were significantly reduced, and the overall compactness was further improved. (3) The enhancement mechanism of microbial consolidation of fine-grained soils by red mud is mainly due to the presence of chemically active β-C2S and calcium oxide in red mud. These active calcium-based components undergo hydration and carbonation reactions under the action of microbial mineralization, generating calcium carbonate and hydrated calcium silicate, which improves the cement yield and enhances the intergranular bond strength, compactness and overall reinforcement effect of the treated soil.
{"title":"Experimental study on improving the effect of microorganisms in solidifying fine-grained soil by red mud","authors":"Peng Liu , Yu Cheng , Guanghui Shao","doi":"10.1016/j.sandf.2024.101562","DOIUrl":"10.1016/j.sandf.2024.101562","url":null,"abstract":"<div><div>To improve the reinforcement effect of MICP technology on fine-grained soil, and consider the fine particle size and activity characteristics of red mud, the experiment of red mud strengthening MICP solidified fine-grained soil was designed and carried out. Combined with mechanical test and microstructural analysis, the enhancing mechanism of red mud on microbial solidified fine-grained soil was comprehensively evaluated. The results show that: (1) Red mud can significantly improve the production of cement during microbial reinforcement of fine-grained soils; the optimal dosage of red mud is 20 %, which increases the strength by 34.6 % and the production of cement by 42.9 %, compared with conventional MICP. (2) After red mud was incorporated into the soil, the pore volume and pore diameter of the treated soil were significantly reduced, and the overall compactness was further improved. (3) The enhancement mechanism of microbial consolidation of fine-grained soils by red mud is mainly due to the presence of chemically active β-C<sub>2</sub>S and calcium oxide in red mud. These active calcium-based components undergo hydration and carbonation reactions under the action of microbial mineralization, generating calcium carbonate and hydrated calcium silicate, which improves the cement yield and enhances the intergranular bond strength, compactness and overall reinforcement effect of the treated soil.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 1","pages":"Article 101562"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143153265","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 : 2025-02-01DOI: 10.1016/j.sandf.2024.101544
Takashi Kiyota , Masataka Shiga , Koji Mori , Toshihiko Katagiri , Hisashi Furuichi , Hendra Setiawan
On 28 September 2018, the Mw 7.5 Sulawesi earthquake occurred in Indonesia, triggering long-distance flow-type landslides on very gentle slopes in and around Palu City. In order to investigate the triggering mechanism of these landslides, this study firstly compiled the field investigations that have been conducted since immediately after the earthquake and a soil profile of the landslide areas. Secondly, a groundwater flow analysis was carried out for the landslide in Petobo on the basis of the estimated soil cross-section. The results showed that, prior to the 2018 earthquake, there was confined groundwater with a water pressure of 40–60 kPa above what would be expected from the hydrostatic conditions in the flow zone of the landslide area. Finally, a simplified liquefaction analysis was performed using the groundwater pressure obtained by the groundwater flow analysis. The results indicated that, although the flow zone in the landslide area consisted of subsoils, including a relatively dense silty sand layer, it is likely that the significant liquefaction that occurred during the 2018 earthquake was due to the presence of confined groundwater. Furthermore, the authors concluded that the liquefaction probably contributed to the prolonged upward flow of large quantities of confined groundwater from aquifers located more than 20 m in depth below the ground surface, which resulted in a long-distance flow-type landslide by muddying the surface layer. It was also shown that the presence of an irrigation channel just above the landslide areas on the eastern side of Palu Valley had little effect on the sequence of landslide mechanism.
{"title":"Triggering mechanism of long-distance flow-type landslides caused by 2018 Sulawesi Earthquake, Indonesia","authors":"Takashi Kiyota , Masataka Shiga , Koji Mori , Toshihiko Katagiri , Hisashi Furuichi , Hendra Setiawan","doi":"10.1016/j.sandf.2024.101544","DOIUrl":"10.1016/j.sandf.2024.101544","url":null,"abstract":"<div><div>On 28 September 2018, the Mw 7.5 Sulawesi earthquake occurred in Indonesia, triggering long-distance flow-type landslides on very gentle slopes in and around Palu City. In order to investigate the triggering mechanism of these landslides, this study firstly compiled the field investigations that have been conducted since immediately after the earthquake and a soil profile of the landslide areas. Secondly, a groundwater flow analysis was carried out for the landslide in Petobo on the basis of the estimated soil cross-section. The results showed that, prior to the 2018 earthquake, there was confined groundwater with a water pressure of 40–60 kPa above what would be expected from the hydrostatic conditions in the flow zone of the landslide area. Finally, a simplified liquefaction analysis was performed using the groundwater pressure obtained by the groundwater flow analysis. The results indicated that, although the flow zone in the landslide area consisted of subsoils, including a relatively dense silty sand layer, it is likely that the significant liquefaction that occurred during the 2018 earthquake was due to the presence of confined groundwater. Furthermore, the authors concluded that the liquefaction probably contributed to the prolonged upward flow of large quantities of confined groundwater from aquifers located more than 20 m in depth below the ground surface, which resulted in a long-distance flow-type landslide by muddying the surface layer. It was also shown that the presence of an irrigation channel just above the landslide areas on the eastern side of Palu Valley had little effect on the sequence of landslide mechanism.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 1","pages":"Article 101544"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143153209","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 : 2025-02-01DOI: 10.1016/j.sandf.2024.101558
Lei Lang , Dan-Xuan Xue , Meng Dong , Wei Zhang , Jiang-Shan Li
Sulphoaluminate cement (SAC) is considered a low-carbon and energy-saving cementitious material, compared with ordinary Portland cement. However, the stabilization efficiency and improvement measures of SAC for dredged sediment (DS) are still unclear. This study used SAC as stabilizer for DS with high water content, and nanoparticles including nano-SiO2 (NS), nano-MgO (NM) and nano-Al2O3 (NA) were incorporated as nano-modifiers. Unconfined compressive strength (UCS) tests were carried out to evaluate the strength development of SAC-stabilized DS (SDS) and nano-modified SDS considering multiple influencing factors. Furthermore, the micro-mechanisms characterizing the strength development of SDS and nano-modified SDS were clarified and discussed based on X-ray diffraction (XRD) and scanning electron microscopy (SEM) tests. The results present that increasing SAC content or decreasing water content can obviously enhance the strength gaining of SDS, while the strength reduction also occurred. Incorporating suitable nanoparticles could significantly improve the strength gaining and simultaneously avoid the strength reduction of SDS. The optimum content of single NS, NM and NA was respectively 4 %, 6 % and 6 %. Composite nanoparticles containing two types of nanoparticles also exhibit positive effect on the strength gaining of SDS, and the optimum mass ratios of NS-NM, NS-NA and NM-NA were respectively 3:7, 1:9 and 5:5. By comparison, adding 6 % NA to SDS achieved the highest strength gaining. The hydration product ettringite was mainly responsible for the strength development of SDS and nano-modified SDS, and incorporating nanoparticles especially NA contributed to the formation of a tighter structure with stronger cementation inside nano-modified SDS. A conceptual model was proposed to characterize the micro-mechanism of strength development in nano-modified SDS.
{"title":"Strength development of dredged sediment stabilized with nano-modified sulphoaluminate cement","authors":"Lei Lang , Dan-Xuan Xue , Meng Dong , Wei Zhang , Jiang-Shan Li","doi":"10.1016/j.sandf.2024.101558","DOIUrl":"10.1016/j.sandf.2024.101558","url":null,"abstract":"<div><div>Sulphoaluminate cement (SAC) is considered a low-carbon and energy-saving cementitious material, compared with ordinary Portland cement. However, the stabilization efficiency and improvement measures of SAC for dredged sediment (DS) are still unclear. This study used SAC as stabilizer for DS with high water content, and nanoparticles including nano-SiO<sub>2</sub> (NS), nano-MgO (NM) and nano-Al<sub>2</sub>O<sub>3</sub> (NA) were incorporated as nano-modifiers. Unconfined compressive strength (UCS) tests were carried out to evaluate the strength development of SAC-stabilized DS (SDS) and nano-modified SDS considering multiple influencing factors. Furthermore, the micro-mechanisms characterizing the strength development of SDS and nano-modified SDS were clarified and discussed based on X-ray diffraction (XRD) and scanning electron microscopy (SEM) tests. The results present that increasing SAC content or decreasing water content can obviously enhance the strength gaining of SDS, while the strength reduction also occurred. Incorporating suitable nanoparticles could significantly improve the strength gaining and simultaneously avoid the strength reduction of SDS. The optimum content of single NS, NM and NA was respectively 4 %, 6 % and 6 %. Composite nanoparticles containing two types of nanoparticles also exhibit positive effect on the strength gaining of SDS, and the optimum mass ratios of NS-NM, NS-NA and NM-NA were respectively 3:7, 1:9 and 5:5. By comparison, adding 6 % NA to SDS achieved the highest strength gaining. The hydration product ettringite was mainly responsible for the strength development of SDS and nano-modified SDS, and incorporating nanoparticles especially NA contributed to the formation of a tighter structure with stronger cementation inside nano-modified SDS. A conceptual model was proposed to characterize the micro-mechanism of strength development in nano-modified SDS.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 1","pages":"Article 101558"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143153211","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 : 2025-02-01DOI: 10.1016/j.sandf.2024.101566
Sai Ying , Yapeng Cao , Qing Zhang , Xiaozhou Xia , Guoyu Li , Fengxi Zhou , Tao Wen
The freezing temperature jumping phenomenon in saline soils caused the freezing temperature activity model to fail. In this study, the freezing temperatures and the rapid freezing water change Δwff of three typical saline soils (NaCl, Na2SO4, and Na2CO3 saline soils) were measured under different water and salt contents using temperature change curves during cooling. The effects and mechanisms of water content, salt content, and salt type on the freezing temperatures of saline soils were analyzed from three aspects: water activity of pore solutions, salt precipitation, and the rapid freezing water change Δwff. The results indicated that the mechanism by which water and salt content affected the freezing temperature of soil was through changes in the water activity of the pore solution. For salt solutions with solubility insensitive to temperature changes, the activity model adequately described the influence of water activity on the solution’s freezing temperature. For salt solutions with solubility highly sensitive to temperature changes, the activity model was applicable when the salt concentration was less than or equal to the jump characteristic concentration. When the salt concentration exceeded the jump characteristic concentration, the freezing temperature jump phenomenon occurred, rendering the activity model inapplicable. Solution salt precipitation caused the freezing temperature jump phenomenon. For saline soils with salt solubility significantly affected by temperature, salt precipitation should be considered when calculating freezing temperatures. The soil’s freezing temperature, as measured by the freezing temperature curve, was influenced by the rapid freezing water change Δwff. When the rapid freezing water change Δwff was greater than or equal to the critical change in frozen water content Δwcrf, the soil’s freezing temperature equaled the equilibrium temperature of the pore solution. When the rapid freezing water change Δwff was less than the critical change in frozen water content Δwcrf, the freezing temperature gradually decreased from the equilibrium temperature of the pore solution to the supercooling temperature as the rapid freezing water change Δwff decreased.
{"title":"The effect of salt on the freezing temperature of saline soil","authors":"Sai Ying , Yapeng Cao , Qing Zhang , Xiaozhou Xia , Guoyu Li , Fengxi Zhou , Tao Wen","doi":"10.1016/j.sandf.2024.101566","DOIUrl":"10.1016/j.sandf.2024.101566","url":null,"abstract":"<div><div>The freezing temperature jumping phenomenon in saline soils caused the freezing temperature activity model to fail. In this study, the freezing temperatures and the rapid freezing water change Δ<em>w</em><sub>ff</sub> of three typical saline soils (NaCl, Na<sub>2</sub>SO<sub>4</sub>, and Na<sub>2</sub>CO<sub>3</sub> saline soils) were measured under different water and salt contents using temperature change curves during cooling. The effects and mechanisms of water content, salt content, and salt type on the freezing temperatures of saline soils were analyzed from three aspects: water activity of pore solutions, salt precipitation, and the rapid freezing water change Δ<em>w</em><sub>ff</sub>. The results indicated that the mechanism by which water and salt content affected the freezing temperature of soil was through changes in the water activity of the pore solution. For salt solutions with solubility insensitive to temperature changes, the activity model adequately described the influence of water activity on the solution’s freezing temperature. For salt solutions with solubility highly sensitive to temperature changes, the activity model was applicable when the salt concentration was less than or equal to the jump characteristic concentration. When the salt concentration exceeded the jump characteristic concentration, the freezing temperature jump phenomenon occurred, rendering the activity model inapplicable. Solution salt precipitation caused the freezing temperature jump phenomenon. For saline soils with salt solubility significantly affected by temperature, salt precipitation should be considered when calculating freezing temperatures. The soil’s freezing temperature, as measured by the freezing temperature curve, was influenced by the rapid freezing water change Δ<em>w</em><sub>ff</sub>. When the rapid freezing water change Δ<em>w</em><sub>ff</sub> was greater than or equal to the critical change in frozen water content Δ<em>w</em><sub>crf</sub>, the soil’s freezing temperature equaled the equilibrium temperature of the pore solution. When the rapid freezing water change Δ<em>w</em><sub>ff</sub> was less than the critical change in frozen water content Δ<em>w</em><sub>crf</sub>, the freezing temperature gradually decreased from the equilibrium temperature of the pore solution to the supercooling temperature as the rapid freezing water change Δ<em>w</em><sub>ff</sub> decreased.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 1","pages":"Article 101566"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143153254","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}
In the Niigata-ken Chuetsu-oki Earthquake of 2007, ground liquefaction was outstanding at the foot of a sand dune and in old river channels. Although no distinct disaster was found in the clayey ground after the earthquake, the long-term settlement of the ground was observed after the earthquake in the Shinbashi district of Kashiwazaki City. At one observation site, the cumulated ground subsidence of the layers from the ground surface to a depth of 23 m had reached 71 mm 14 years after the earthquake. In order to study the mechanism of the deformation during the earthquake and the long-term settlement after the earthquake, ground investigations, such as a boring survey at the observation site and indoor element tests on sampled soil, were conducted in this study. The results showed that the sampled soil was very soft, strongly compressible, and relatively highly structured. Subsequently, the transformation stress-cyclic mobility (TS-CM) constitutive model, developed by Zhang et al. (2007), was used to simulate the results of the indoor element tests, and the soil parameters were determined based on the results of these tests. The TS-CM model contains the concepts of subloading, described by Hashiguchi (1977), and superloading, described by Asaoka et al. (2002). Therefore, the subsidence behavior of the ground was simulated by a soil–water coupling elasto-plastic finite element (FE) analysis using the TS-CM constitutive model and the determined parameters. The FE simulation results agreed well with the actual site subsidence observation data. Based on the simulation results, the post-earthquake behavior of the soft clay and its mechanism were discussed, and the successive subsidence was predicted forward. According to the simulation results, the relatively highly structured susceptible clay at this site was found to have greater potential in terms of long-term consolidation than relatively less structured susceptible clay due to the large excess pore water pressure generation during the ground motion and the consolidation process after the earthquake. This conclusion was verified by consolidation tests on two types of clay.
{"title":"Study on long-term subsidence of soft clay due to Niigata-ken Chuetsu-oki earthquake of 2007","authors":"Yazhou Jiang , Koichi Isobe , Satoru Ohtsuka , Toshiyuki Takahara","doi":"10.1016/j.sandf.2024.101536","DOIUrl":"10.1016/j.sandf.2024.101536","url":null,"abstract":"<div><div>In the Niigata-ken Chuetsu-oki Earthquake of 2007, ground liquefaction was outstanding at the foot of a sand dune and in old river channels. Although no distinct disaster was found in the clayey ground after the earthquake, the long-term settlement of the ground was observed after the earthquake in the Shinbashi district of Kashiwazaki City. At one observation site, the cumulated ground subsidence of the layers from the ground surface to a depth of 23 m had reached 71 mm 14 years after the earthquake. In order to study the mechanism of the deformation during the earthquake and the long-term settlement after the earthquake, ground investigations, such as a boring survey at the observation site and indoor element tests on sampled soil, were conducted in this study. The results showed that the sampled soil was very soft, strongly compressible, and relatively highly structured. Subsequently, the transformation stress-cyclic mobility (TS-CM) constitutive model, developed by Zhang et al. (2007), was used to simulate the results of the indoor element tests, and the soil parameters were determined based on the results of these tests. The TS-CM model contains the concepts of subloading, described by Hashiguchi (1977), and superloading, described by Asaoka et al. (2002). Therefore, the subsidence behavior of the ground was simulated by a soil–water coupling elasto-plastic finite element (FE) analysis using the TS-CM constitutive model and the determined parameters. The FE simulation results agreed well with the actual site subsidence observation data. Based on the simulation results, the post-earthquake behavior of the soft clay and its mechanism were discussed, and the successive subsidence was predicted forward. According to the simulation results, the relatively highly structured susceptible clay at this site was found to have greater potential in terms of long-term consolidation than relatively less structured susceptible clay due to the large excess pore water pressure generation during the ground motion and the consolidation process after the earthquake. This conclusion was verified by consolidation tests on two types of clay.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 1","pages":"Article 101536"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143153210","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 : 2025-02-01DOI: 10.1016/j.sandf.2025.101567
Mudassir Mehmood , Yuancheng Guo , Yunlong Liu , Lei Wang , Wen Nie , Bantayehu Uba Uge , Sharafat Ali , Chen Xuanyu , Yingao Zhao
Enzyme induced carbonate precipitation (EICP) is gaining more and more recognition that can be utilized on-site to enhance the quality of the weak soil. In this experimental study, a novel approach that combines EICP and eggshell powder (ESP) to strengthen the engineering characteristics of natural expansive soil has been implemented. The engineering properties of expansive soil were examined using the environmentally friendly method EICP with an optimal 0.75 mol/L concentration and 14% ESP optimal content, with varying curing durations. ESP serves as a filler between particles and also a nucleation site to promote the precipitation of calcium carbonate. A thorough examination of the soil’s microstructure development after treatment was additionally executed through scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The findings demonstrated that combining EICP and ESP decreases the swelling pressure about 25 times, compared with the individual treatment that yielded 5 and 1.5 times reduction for EICP and ESP, respectively. Additionally, the combined treatment led to an increase in the unconfined compressive strength, cohesion, internal friction angle, unsoaked CBR, and soaked CBR by 3, 1.6, 1.8, 8.0, and 9.5 times, respectively, indicating better enhancements than the individual treatments of EICP and ESP. Moreover, at the microstructural level, SEM imagery demonstrated a highly reinforced soil composite. The XRD analysis unveils distinct mineralogical changes, predominantly characterized by enhanced calcite formation and a refined microstructural composition. This study highlights the synergistic potential of combining EICP and ESP as stabilizing additives to enhance the engineering properties of expansive soil. Beyond soil enhancement, this innovative blend offers a sustainable solution by repurposing agrowaste. The mutual incorporation of EICP and ESP emerges as a promising strategy for advancing sustainable civil infrastructure development.
{"title":"Experimental study on the engineering characteristics of expansive soil improved conjointly using enzyme induced carbonate precipitation and eggshell powder","authors":"Mudassir Mehmood , Yuancheng Guo , Yunlong Liu , Lei Wang , Wen Nie , Bantayehu Uba Uge , Sharafat Ali , Chen Xuanyu , Yingao Zhao","doi":"10.1016/j.sandf.2025.101567","DOIUrl":"10.1016/j.sandf.2025.101567","url":null,"abstract":"<div><div>Enzyme induced carbonate precipitation (EICP) is gaining more and more recognition that can be utilized on-site to enhance the quality of the weak soil. In this experimental study, a novel approach that combines EICP and eggshell powder (ESP) to strengthen the engineering characteristics of natural expansive soil has been implemented. The engineering properties of expansive soil were examined using the environmentally friendly method EICP with an optimal 0.75 mol/L concentration and 14% ESP optimal content, with varying curing durations. ESP serves as a filler between particles and also a nucleation site to promote the precipitation of calcium carbonate. A thorough examination of the soil’s microstructure development after treatment was additionally executed through scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The findings demonstrated that combining EICP and ESP decreases the swelling pressure about 25 times, compared with the individual treatment that yielded 5 and 1.5 times reduction for EICP and ESP, respectively. Additionally, the combined treatment led to an increase in the unconfined compressive strength, cohesion, internal friction angle, unsoaked CBR, and soaked CBR by 3, 1.6, 1.8, 8.0, and 9.5 times, respectively, indicating better enhancements than the individual treatments of EICP and ESP. Moreover, at the microstructural level, SEM imagery demonstrated a highly reinforced soil composite. The XRD analysis unveils distinct mineralogical changes, predominantly characterized by enhanced calcite formation and a refined microstructural composition. This study highlights the synergistic potential of combining EICP and ESP as stabilizing additives to enhance the engineering properties of expansive soil. Beyond soil enhancement, this innovative blend offers a sustainable solution by repurposing agrowaste. The mutual incorporation of EICP and ESP emerges as a promising strategy for advancing sustainable civil infrastructure development.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 1","pages":"Article 101567"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143153202","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 : 2025-02-01DOI: 10.1016/j.sandf.2024.101564
Mitsu Okamura , Mizuki Suyama , Kohei Ono
Sheet-pile enclosures are often employed as liquefaction countermeasures for river levees in Japan. However, the stiffness of the sheet piles alone is often insufficient to maintain levees on liquefied foundation soil high enough to prevent overflooding. Sheet piles with additional members having drainage ability have been developed and employed, which are expected to provide the combined effects of lateral confinement and dissipation of excess pore pressure from the liquefiable soil beneath the levees. In this study, a series of centrifuge tests was conducted to assess the liquefaction-induced settlement of levees and the excess pore pressure generated in sand beds enclosed by sheet piles with and without drainage ability. The effects of the drainage ability were studied for liquefiable foundation soil with a wide range of permeabilities. The results confirmed that the settlement in a sand bed is closely related to the excess pore pressure. Additionally, a practical method was developed for predicting excess pore pressure and then validated through a comparison with test observations. Using this procedure, the effects of the sand-bed geometry, levee height, and severity of the earthquake shaking were studied in relation to the characteristics of the resistance of the sand to liquefaction on the excess pore pressure. Moreover, the applicability of drainage members to a Japanese river levee countermeasure project was analyzed. For practical use in river levee rehabilitation projects, drainage members were confirmed to be more effective for sand with a higher liquefaction-resistance. Owing to the high maximum acceleration of ground motions stipulated in the design code, these drainage members may not be effective for sand with permeabilities in the order of 10−5 m/s or lower. In addition, the slopes of the liquefaction resistance curves of the sand were observed to significantly affect the effectiveness of the drainage members. Therefore, the liquefaction-resistance curves are considered to be more important than the liquefaction-resistance ratio alone when designing drainage members as a liquefaction countermeasure.
{"title":"Effectiveness of sheet pile enclosure with drainage ability as liquefaction countermeasure for river levees","authors":"Mitsu Okamura , Mizuki Suyama , Kohei Ono","doi":"10.1016/j.sandf.2024.101564","DOIUrl":"10.1016/j.sandf.2024.101564","url":null,"abstract":"<div><div>Sheet-pile enclosures are often employed as liquefaction countermeasures for river levees in Japan. However, the stiffness of the sheet piles alone is often insufficient to maintain levees on liquefied foundation soil high enough to prevent overflooding. Sheet piles with additional members having drainage ability have been developed and employed, which are expected to provide the combined effects of lateral confinement and dissipation of excess pore pressure from the liquefiable soil beneath the levees. In this study, a series of centrifuge tests was conducted to assess the liquefaction-induced settlement of levees and the excess pore pressure generated in sand beds enclosed by sheet piles with and without drainage ability. The effects of the drainage ability were studied for liquefiable foundation soil with a wide range of permeabilities. The results confirmed that the settlement in a sand bed is closely related to the excess pore pressure. Additionally, a practical method was developed for predicting excess pore pressure and then validated through a comparison with test observations. Using this procedure, the effects of the sand-bed geometry, levee height, and severity of the earthquake shaking were studied in relation to the characteristics of the resistance of the sand to liquefaction on the excess pore pressure. Moreover, the applicability of drainage members to a Japanese river levee countermeasure project was analyzed. For practical use in river levee rehabilitation projects, drainage members were confirmed to be more effective for sand with a higher liquefaction-resistance. Owing to the high maximum acceleration of ground motions stipulated in the design code, these drainage members may not be effective for sand with permeabilities in the order of 10<sup>−5</sup> m/s or lower. In addition, the slopes of the liquefaction resistance curves of the sand were observed to significantly affect the effectiveness of the drainage members. Therefore, the liquefaction-resistance curves are considered to be more important than the liquefaction-resistance ratio alone when designing drainage members as a liquefaction countermeasure.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 1","pages":"Article 101564"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143152556","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 : 2025-02-01DOI: 10.1016/j.sandf.2024.101561
Xiaomeng Xue , Ga Zhang
With the increasing development of underground engineering, various support systems of foundation pits are emerging, and the pile-anchor support system is widely used in deep foundation pit engineering construction. A series of centrifuge model tests for foundation pit excavation was conducted to investigate the deformation laws of the retaining pile and the soil for pile-anchor support system. Compared with the test results of cantilever pile support system, the horizontal displacement of the retaining pile and the settlement of the retained soil significantly decreased, as well as the deformation mode of the pile and the horizontal and vertical distribution of the deformation of retained soil were different for the pile-anchor support system. The movement of retained soil tended towards the vertical due to the increasing deformation of the entire pile, further leading to the variations of the displacement distributions of the soil. The anchor limited the deflection of the pile and thus resulted in a significant reduction of soil deformation. The direction of tangential relative displacement of the anchor and soil changed during the development of the pile top displacement. Accordingly, the pile-anchor-soil interaction was categorized into three different states, which were affected by inclination angles of the anchor as well. Furthermore, it is concluded that there was an optimal inclination angle of the anchor by comparing the test results of pile-anchor support system with various inclination angles.
{"title":"Centrifuge model test study on pile-anchor support system","authors":"Xiaomeng Xue , Ga Zhang","doi":"10.1016/j.sandf.2024.101561","DOIUrl":"10.1016/j.sandf.2024.101561","url":null,"abstract":"<div><div>With the increasing development of underground engineering, various support systems of foundation pits are emerging, and the pile-anchor support system is widely used in deep foundation pit engineering construction. A series of centrifuge model tests for foundation pit excavation was conducted to investigate the deformation laws of the retaining pile and the soil for pile-anchor support system. Compared with the test results of cantilever pile support system, the horizontal displacement of the retaining pile and the settlement of the retained soil significantly decreased, as well as the deformation mode of the pile and the horizontal and vertical distribution of the deformation of retained soil were different for the pile-anchor support system. The movement of retained soil tended towards the vertical due to the increasing deformation of the entire pile, further leading to the variations of the displacement distributions of the soil. The anchor limited the deflection of the pile and thus resulted in a significant reduction of soil deformation. The direction of tangential relative displacement of the anchor and soil changed during the development of the pile top displacement. Accordingly, the pile-anchor-soil interaction was categorized into three different states, which were affected by inclination angles of the anchor as well. Furthermore, it is concluded that there was an optimal inclination angle of the anchor by comparing the test results of pile-anchor support system with various inclination angles.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 1","pages":"Article 101561"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143153252","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 : 2025-02-01DOI: 10.1016/j.sandf.2025.101572
Fuchen Teng, Yong Cheng Sie
Soft clay layers in urban areas pose challenges due to low strength and high compressibility, complicating urban construction. Microbially induced carbonate precipitation (MICP) has demonstrated its ability to enhance soil strength in sandy soils. However, research on the utilization of MICP for clay has been limited. Thus, this paper introduced a new method that combines MICP with grouting. The treated MICP solutions were injected into the consolidated clay samples in a triaxial system to simulate the improvement of grouting in the consolidated soil layer in the field. A series of modified triaxial tests, fluorescent nucleic acid stains, solution/soil pH tests, and microscopic observation tests were conducted. Results indicated a 1.7 times increase in soil strength with bioaugmentation treatment on clay under 150 kPa consolidation stress. Additionally, the weight of CaCO3 increased by 3.2 g, achieving a precipitation ratio of 58 %. The injected bacteria were observed in the bottom-most and center of the sample, confirming their mobility in the clay. The enhancement of shear strength on treated clay involved not only urease-producing bacteria but also environmental chemical reactions and natural bacterial effects. Furthermore, a microstructure changes of MICP in clay was observed, wherein CaCO3 effectively filled the pore spaces and bonded particles together to enhance strength. Based on the results, through MICP treatment with injection method, consolidated clay enhances its mechanical behavior and microstructural formation to improve the shear strength.
{"title":"Simulating field grouting to improve the shear strength of consolidated clay by microbially induced carbonate precipitation","authors":"Fuchen Teng, Yong Cheng Sie","doi":"10.1016/j.sandf.2025.101572","DOIUrl":"10.1016/j.sandf.2025.101572","url":null,"abstract":"<div><div>Soft clay layers in urban areas pose challenges due to low strength and high compressibility, complicating urban construction. Microbially induced carbonate precipitation (MICP) has demonstrated its ability to enhance soil strength in sandy soils. However, research on the utilization of MICP for clay has been limited. Thus, this paper introduced a new method that combines MICP with grouting. The treated MICP solutions were injected into the consolidated clay samples in a triaxial system to simulate the improvement of grouting in the consolidated soil layer in the field. A series of modified triaxial tests, fluorescent nucleic acid stains, solution/soil pH tests, and microscopic observation tests were conducted. Results indicated a 1.7 times increase in soil strength with bioaugmentation treatment on clay under 150 kPa consolidation stress. Additionally, the weight of CaCO<sub>3</sub> increased by 3.2 g, achieving a precipitation ratio of 58 %. The injected bacteria were observed in the bottom-most and center of the sample, confirming their mobility in the clay. The enhancement of shear strength on treated clay involved not only urease-producing bacteria but also environmental chemical reactions and natural bacterial effects. Furthermore, a microstructure changes of MICP in clay was observed, wherein CaCO<sub>3</sub> effectively filled the pore spaces and bonded particles together to enhance strength. Based on the results, through MICP treatment with injection method, consolidated clay enhances its mechanical behavior and microstructural formation to improve the shear strength.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"65 1","pages":"Article 101572"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143153259","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 : 2024-12-01DOI: 10.1016/j.sandf.2024.101542
Fu Chen , Aiping Tang
Vacuum preloading has been a widely used consolidation method for soft clay ground improvement since the 1980s. Consolidation theory only explains the radial drainage process from soil to prefabricated vertical drains (PVD); however, the complete drainage path mechanism by which water drains vertically through PVD to the upper horizontal sand drainage layer and eventually to vacuum pumps is still unclear, resulting in controversies about vacuum preloading. A large oedometer test was performed to study the complete drainage-path mechanism for vacuum preloading. During vacuum preloading, the soil’s average internal temperature decreased to 5 °C below initial temperature, with the lowest temperate occurring near the PVD, which was 2 °C lower than the outskirt. A complete drainage path mechanism is proposed based on the phenomenon of internal temperature decreases. Water evaporates only in the PVD, and the vertical movement of water in the PVD is caused by a density difference between the gas molecules that is independent of gravity. Finally, the proposed mechanism was used to explain the controversy about vacuum preloading. For example, vacuum should not decay along the PVD, vacuum acting elevation at the top or bottom of the PVD has no effect on the final vacuum preloading effectiveness, there is no unsaturated zone formed, and the groundwater level does not drop during vacuum preloading.
{"title":"Study on drainage mechanism of complete path for vacuum preloading based on thermodynamics theory","authors":"Fu Chen , Aiping Tang","doi":"10.1016/j.sandf.2024.101542","DOIUrl":"10.1016/j.sandf.2024.101542","url":null,"abstract":"<div><div>Vacuum preloading has been a widely used consolidation method for soft clay ground improvement since the 1980s. Consolidation theory only explains the radial drainage process from soil to prefabricated vertical drains (PVD); however, the complete drainage path mechanism by which water drains vertically through PVD to the upper horizontal sand drainage layer and eventually to vacuum pumps is still unclear, resulting in controversies about vacuum preloading. A large oedometer test was performed to study the complete drainage-path mechanism for vacuum preloading. During vacuum preloading, the soil’s average internal temperature decreased to 5 °C below initial temperature, with the lowest temperate occurring near the PVD, which was 2 °C lower than the outskirt. A complete drainage path mechanism is proposed based on the phenomenon of internal temperature decreases. Water evaporates only in the PVD, and the vertical movement of water in the PVD is caused by a density difference between the gas molecules that is independent of gravity. Finally, the proposed mechanism was used to explain the controversy about vacuum preloading. For example, vacuum should not decay along the PVD, vacuum acting elevation at the top or bottom of the PVD has no effect on the final vacuum preloading effectiveness, there is no unsaturated zone formed, and the groundwater level does not drop during vacuum preloading.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"64 6","pages":"Article 101542"},"PeriodicalIF":3.3,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142747452","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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