Pub Date : 2024-10-10DOI: 10.1016/j.bgtech.2024.100144
Reena N. Hora , Md Mizanur Rahman , Md Rajibul Karim , Simon Beecham
Many past studies have investigated the Unconfined Compressive Strength (UCS) behaviour of MICP-treated sandy soils and developed empirical relationships to predict strength improvement. While the UCS of MICP-treated soils can be affected by many factors such as chemical concentration, temperature, and biochemistry, it has been found that particle size () is one of the important contributing factors, but most of the previously published studies have not considered it. This study applied MICP on three different variants of Adelaide Industrial (AI) clean sands with different grain size distributions to evaluate the effect on UCS and Calcium Carbonate () precipitation. To better understand the influence of particle size, this study also collected literature data on UCS, content and soil grading properties. A numerical method was used to interpolate the distribution of the combined data (literature and experimental) in 3D space to establish a clear correlation between UCS, content (CC) and the soil grading properties. So, contour plots were generated between UCS, CC, and and other soil grading properties. Where the 2D and 3D plots could not clearly present the influence of on the variation of UCS and CC, contour plots presented the distribution rather clearly. The contour plots showed a visible trend in the variation of UCS and CC for and Coefficient of Curvature (), but not for Coefficient of Uniformity ().
{"title":"Evaluating the effect of soil grading on the UCS of MICP-treated sandy soils","authors":"Reena N. Hora , Md Mizanur Rahman , Md Rajibul Karim , Simon Beecham","doi":"10.1016/j.bgtech.2024.100144","DOIUrl":"10.1016/j.bgtech.2024.100144","url":null,"abstract":"<div><div>Many past studies have investigated the Unconfined Compressive Strength (UCS) behaviour of MICP-treated sandy soils and developed empirical relationships to predict strength improvement. While the UCS of MICP-treated soils can be affected by many factors such as chemical concentration, temperature, and biochemistry, it has been found that particle size (<span><math><msub><mrow><mi>d</mi></mrow><mrow><mn>10</mn></mrow></msub></math></span>) is one of the important contributing factors, but most of the previously published studies have not considered it. This study applied MICP on three different variants of Adelaide Industrial (AI) clean sands with different grain size distributions to evaluate the effect on UCS and Calcium Carbonate (<span><math><mrow><mi>CaC</mi><msub><mrow><mi>O</mi></mrow><mrow><mn>3</mn></mrow></msub></mrow></math></span>) precipitation. To better understand the influence of particle size, this study also collected literature data on UCS, <span><math><mrow><mi>CaC</mi><msub><mrow><mi>O</mi></mrow><mrow><mn>3</mn></mrow></msub></mrow></math></span> content and soil grading properties. A numerical method was used to interpolate the distribution of the combined data (literature and experimental) in 3D space to establish a clear correlation between UCS, <span><math><mrow><mi>CaC</mi><msub><mrow><mi>O</mi></mrow><mrow><mn>3</mn></mrow></msub></mrow></math></span> content (CC) and the soil grading properties. So, contour plots were generated between UCS, CC, and <span><math><msub><mrow><mi>d</mi></mrow><mrow><mn>10</mn></mrow></msub></math></span> and other soil grading properties. Where the 2D and 3D plots could not clearly present the influence of <span><math><msub><mrow><mi>d</mi></mrow><mrow><mn>10</mn></mrow></msub></math></span> on the variation of UCS and CC, contour plots presented the distribution rather clearly. The contour plots showed a visible trend in the variation of UCS and CC for <span><math><msub><mrow><mi>d</mi></mrow><mrow><mn>10</mn></mrow></msub></math></span> and Coefficient of Curvature (<span><math><msub><mrow><mi>C</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span>), but not for Coefficient of Uniformity (<span><math><msub><mrow><mi>C</mi></mrow><mrow><mi>u</mi></mrow></msub></math></span>).</div></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"4 1","pages":"Article 100144"},"PeriodicalIF":0.0,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145765760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-09DOI: 10.1016/j.bgtech.2024.100143
Yuhao Li , Xiangwei Fang , Chunni Shen , Wenchen Jiang , Sheng Huang , Guoliang Ma
Traditional soil stabilizers, such as cement and lime, typically entail substantial energy consumption and environmental pollution. In contrast, bio-enzyme has emerged as a promising alternative, aligning with the imperatives of sustainable development, cost-effectiveness, and environmental friendliness. Bio-enzymes are primarily one or more protein molecules that catalyzes chemical reactions in the soil to form a cementing bond that stabilizes the soil structure and reduces the soil’s affinity for water. Currently, a plethora of studies on bio-enzyme have been conducted by scholars worldwide, yet there remains a notable absence of the systematic organization and comprehensive review of these findings. This study offers a thorough examination of bio-enzyme technology, encompassing its biochemical properties, mechanisms, the engineering properties of stabilized soil, bio-enzymatic composites, and its engineering applications. And current trends and future prospects of bio-enzyme are also scrutinized. This forward-looking study indicates that bio-enzyme functions through mechanisms such as cation exchange, specific binding, and surfactants, among others to diminish the electric double layer thickness and hydrophilicity of soil, consequently enhancing engineering properties of soil. And the improvement performance can be influenced by various factors, including soil properties, enzyme dosage, specificity, and sample preparation, etc. It is also noted that the composites of bio-enzyme with conventional stabilizers tend to enhance improvement performance more efficiently. The engineering applications of bio-enzyme have demonstrated its superiority over traditional stabilizers in soil improvement. However, the performance of treated soils with available bio-enzyme remains limited, highlighting the necessity for extracting novel bio-enzyme form plants/animals and determining its mechanisms and engineering mechanical properties. It is also essential to develop more bio-enzymatic composites and conduct application in-situ to develop relevant standards and application guidelines.
{"title":"Review of bio-enzyme for soil improvement","authors":"Yuhao Li , Xiangwei Fang , Chunni Shen , Wenchen Jiang , Sheng Huang , Guoliang Ma","doi":"10.1016/j.bgtech.2024.100143","DOIUrl":"10.1016/j.bgtech.2024.100143","url":null,"abstract":"<div><div>Traditional soil stabilizers, such as cement and lime, typically entail substantial energy consumption and environmental pollution. In contrast, bio-enzyme has emerged as a promising alternative, aligning with the imperatives of sustainable development, cost-effectiveness, and environmental friendliness. Bio-enzymes are primarily one or more protein molecules that catalyzes chemical reactions in the soil to form a cementing bond that stabilizes the soil structure and reduces the soil’s affinity for water. Currently, a plethora of studies on bio-enzyme have been conducted by scholars worldwide, yet there remains a notable absence of the systematic organization and comprehensive review of these findings. This study offers a thorough examination of bio-enzyme technology, encompassing its biochemical properties, mechanisms, the engineering properties of stabilized soil, bio-enzymatic composites, and its engineering applications. And current trends and future prospects of bio-enzyme are also scrutinized. This forward-looking study indicates that bio-enzyme functions through mechanisms such as cation exchange, specific binding, and surfactants, among others to diminish the electric double layer thickness and hydrophilicity of soil, consequently enhancing engineering properties of soil. And the improvement performance can be influenced by various factors, including soil properties, enzyme dosage, specificity, and sample preparation, etc. It is also noted that the composites of bio-enzyme with conventional stabilizers tend to enhance improvement performance more efficiently. The engineering applications of bio-enzyme have demonstrated its superiority over traditional stabilizers in soil improvement. However, the performance of treated soils with available bio-enzyme remains limited, highlighting the necessity for extracting novel bio-enzyme form plants/animals and determining its mechanisms and engineering mechanical properties. It is also essential to develop more bio-enzymatic composites and conduct application in-situ to develop relevant standards and application guidelines.</div></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"4 1","pages":"Article 100143"},"PeriodicalIF":0.0,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145765803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Microbially induced carbonate precipitation (MICP) is an eco-friendly soil improvement technique. However, this method still has some drawbacks, such as low conversion efficiency of CaCO3 crystallization, insufficient strength for certain applications, and requiring multiple treatments. Previous studies have reported that sticky rice can regulate CaCO3 crystals (i.e., chemical CaCO3) in the sticky rice-lime mortar, showing potential for improving the bio-cementation. Therefore, this study explored the possibility of using sticky rice to enhance the biocementation effect. Tests were carried out to assess the strength and permeability of bio-cemented sand with the inclusion of sticky rice. The results indicated that sticky rice may regulate the type and size of bio-CaCO3 crystals, and the use of an appropriate amount of sticky rice as additive could increase the strength of sand columns by regulating CaCO3 crystallization. Polyhedral calcites may be more favourable for the increasing strength than some vaterites with a hollow spherical structure. The combination of MICP and sticky rice can significantly decrease the coefficient of permeability to a value that was much lower than that by using sticky rice and MICP alone. Bio-CaCO3 immobilized the sticky rice on one end on sand particles, and the reticulated structure of sticky rice divided large pores into small pores, which may be the important cause of the decrease in permeability coefficient. Finally, this study proposed that the MICP with the sticky rice as an additive may enhance the MICP effect and prevent the surface erosion of coarse-grained sand slopes.
{"title":"Effect of sticky rice on the strength and permeability of bio-cemented sand","authors":"Qiyong Zhang , Jian Chu , Zheng Zhang , Wenhao Wang , Shifan Wu","doi":"10.1016/j.bgtech.2024.100141","DOIUrl":"10.1016/j.bgtech.2024.100141","url":null,"abstract":"<div><div>Microbially induced carbonate precipitation (MICP) is an eco-friendly soil improvement technique. However, this method still has some drawbacks, such as low conversion efficiency of CaCO<sub>3</sub> crystallization, insufficient strength for certain applications, and requiring multiple treatments. Previous studies have reported that sticky rice can regulate CaCO<sub>3</sub> crystals (i.e., chemical CaCO<sub>3</sub>) in the sticky rice-lime mortar, showing potential for improving the bio-cementation. Therefore, this study explored the possibility of using sticky rice to enhance the biocementation effect. Tests were carried out to assess the strength and permeability of bio-cemented sand with the inclusion of sticky rice. The results indicated that sticky rice may regulate the type and size of bio-CaCO<sub>3</sub> crystals, and the use of an appropriate amount of sticky rice as additive could increase the strength of sand columns by regulating CaCO<sub>3</sub> crystallization. Polyhedral calcites may be more favourable for the increasing strength than some vaterites with a hollow spherical structure. The combination of MICP and sticky rice can significantly decrease the coefficient of permeability to a value that was much lower than that by using sticky rice and MICP alone. Bio-CaCO<sub>3</sub> immobilized the sticky rice on one end on sand particles, and the reticulated structure of sticky rice divided large pores into small pores, which may be the important cause of the decrease in permeability coefficient. Finally, this study proposed that the MICP with the sticky rice as an additive may enhance the MICP effect and prevent the surface erosion of coarse-grained sand slopes.</div></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"3 3","pages":"Article 100141"},"PeriodicalIF":0.0,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144563188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-30DOI: 10.1016/j.bgtech.2024.100120
Rafaela Cardoso , Thomas Drouinot , Susana Cardoso de Freitas
This paper presents a microdevice developed to measure the electrical conductivity of a liquid or a saturated porous medium using Wenner method. It is developed in the context of biocementation as soil improvement technique, which is used in Civil Engineering applications to produce calcium carbonate through bacterial or enzymatic activity, replacing the use of other binder materials such as cement or resins, and therefore reducing carbon footprint. The microdevice was used to measure urease activity in the soil interstitial fluid, to investigate if bacterial activity could be affected by the presence of the particles and tortuosity from pore geometry. Such analysis is important to understand biocementation mechanism inside the soil and helps to improve the design of such treatment solutions. The device is basically a squared reservoir printed in polypropylene using a 3D printing machine, incorporating stainless steel electrodes in its base. The electrical resistivity was computed adopting Wenner method, by connecting 4 PCB electrodes to a signal generator and an oscilloscope for measuring the voltage when a AC current of 1 mA was applied. Both square and sinusoidal waves with 5 kHz frequency were selected among other frequencies. The measurements were adjusted during the calibration of the microdevice, done using standard salt solutions with known electrical conductivity measured using an electrical conductivity probe. For the bacterial activity measurements, the bacterial and urea solutions were added to a uniform-graded size quarzitic sand (average diameter 0.3 mm) placed inside the microdevice and covering completely the electrodes. Bacterial activity was not affected by the presence of the sand, which confirms that this treatment is effective for this type of soils.
本文介绍了一种利用温纳法测量液体或饱和多孔介质电导率的微型装置。生物水泥化是一种土壤改良技术，应用于土木工程领域，通过细菌或酶的活性产生碳酸钙，取代水泥或树脂等其他粘结材料的使用，从而减少碳足迹。该微型装置用于测量土壤间隙流体中的脲酶活性，以研究细菌活性是否会受到颗粒存在和孔隙几何形状迂回的影响。此类分析对于了解土壤内部的生物降解机制非常重要，有助于改进此类处理方案的设计。该装置基本上是一个使用 3D 打印机用聚丙烯打印的方形蓄水池，其底部装有不锈钢电极。电阻率的计算采用温纳法，将 4 个 PCB 电极连接到信号发生器和示波器上，以测量施加 1 mA 交流电时的电压。在其他频率中，选择了频率为 5 kHz 的方波和正弦波。在校准微型设备时，使用标准盐溶液对测量结果进行调整，标准盐溶液的电导率是通过电导率探针测量得出的。在测量细菌活性时，将细菌溶液和尿素溶液加入放置在微装置内并完全覆盖电极的大小均匀的石英砂（平均直径 0.3 毫米）中。细菌活性并没有因为沙子的存在而受到影响，这证明这种处理方法对这类土壤是有效的。
{"title":"Miniaturized device to measure urease activity in the soil interstitial fluid using wenner method","authors":"Rafaela Cardoso , Thomas Drouinot , Susana Cardoso de Freitas","doi":"10.1016/j.bgtech.2024.100120","DOIUrl":"10.1016/j.bgtech.2024.100120","url":null,"abstract":"<div><div>This paper presents a microdevice developed to measure the electrical conductivity of a liquid or a saturated porous medium using Wenner method. It is developed in the context of biocementation as soil improvement technique, which is used in Civil Engineering applications to produce calcium carbonate through bacterial or enzymatic activity, replacing the use of other binder materials such as cement or resins, and therefore reducing carbon footprint. The microdevice was used to measure urease activity in the soil interstitial fluid, to investigate if bacterial activity could be affected by the presence of the particles and tortuosity from pore geometry. Such analysis is important to understand biocementation mechanism inside the soil and helps to improve the design of such treatment solutions. The device is basically a squared reservoir printed in polypropylene using a 3D printing machine, incorporating stainless steel electrodes in its base. The electrical resistivity was computed adopting Wenner method, by connecting 4 PCB electrodes to a signal generator and an oscilloscope for measuring the voltage when a AC current of 1 mA was applied. Both square and sinusoidal waves with 5 kHz frequency were selected among other frequencies. The measurements were adjusted during the calibration of the microdevice, done using standard salt solutions with known electrical conductivity measured using an electrical conductivity probe. For the bacterial activity measurements, the bacterial and urea solutions were added to a uniform-graded size quarzitic sand (average diameter 0.3 mm) placed inside the microdevice and covering completely the electrodes. Bacterial activity was not affected by the presence of the sand, which confirms that this treatment is effective for this type of soils.</div></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"3 1","pages":"Article 100120"},"PeriodicalIF":0.0,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Soil contamination remains a global problem, and numerous studies have been published for investigating soil remediation. Thermal desorption remediation (TDR) can significantly reduce the contaminants in the soil within a short time and consequently has been used worldwide. However, the soil properties respond to TDR differently and are dependent on the experimental set-up. The causative mechanisms of these differences are yet to be fully elucidated. A statistical meta-analysis was thus undertaken to evaluate the TDR treatment effects on soil properties and plant performance. This review pointed out that soil clay was reduced by 54.2%, while soil sand content was enhanced by 15.2% after TDR. This might be due to the release of cementing agents from clay minerals that resulted in the formation of soil aggregates. Soil electrical conductivity enhanced by 69.5% after TDR, which might be due to the heating-induced loss of structural hydroxyl groups and the consequent liberation of ions. The treatment of TDR leads to the reduction of plant germination rate, length, and biomass by 19.4%, 44.8%, and 20.2%, respectively, compared to that of control soil. This might be due to the residue of contaminants and the loss of soil fertility during the thermal process that inhibited plant germination and growth. Soil pH and sulfate content increased with heating temperature increased, while soil enzyme activities decreased with thermal temperature increased. Overall, the results suggested that TDR treatment has inhibited plant growth as well as ecological restoration.
{"title":"Thermal desorption remediation effects on soil biogeochemical properties and plant performance: Global meta-analysis","authors":"Jiaxin Liao , Haowen Guo , Sanandam Bordoloi , Denian Li , Yuanxiang Zhang , Junjun Ni , Haoran Yuan , Xudong Zhao","doi":"10.1016/j.bgtech.2024.100140","DOIUrl":"10.1016/j.bgtech.2024.100140","url":null,"abstract":"<div><div>Soil contamination remains a global problem, and numerous studies have been published for investigating soil remediation. Thermal desorption remediation (TDR) can significantly reduce the contaminants in the soil within a short time and consequently has been used worldwide. However, the soil properties respond to TDR differently and are dependent on the experimental set-up. The causative mechanisms of these differences are yet to be fully elucidated. A statistical meta-analysis was thus undertaken to evaluate the TDR treatment effects on soil properties and plant performance. This review pointed out that soil clay was reduced by 54.2%, while soil sand content was enhanced by 15.2% after TDR. This might be due to the release of cementing agents from clay minerals that resulted in the formation of soil aggregates. Soil electrical conductivity enhanced by 69.5% after TDR, which might be due to the heating-induced loss of structural hydroxyl groups and the consequent liberation of ions. The treatment of TDR leads to the reduction of plant germination rate, length, and biomass by 19.4%, 44.8%, and 20.2%, respectively, compared to that of control soil. This might be due to the residue of contaminants and the loss of soil fertility during the thermal process that inhibited plant germination and growth. Soil pH and sulfate content increased with heating temperature increased, while soil enzyme activities decreased with thermal temperature increased. Overall, the results suggested that TDR treatment has inhibited plant growth as well as ecological restoration.</div></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"3 3","pages":"Article 100140"},"PeriodicalIF":0.0,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144557605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-16DOI: 10.1016/j.bgtech.2024.100139
Qi Zhang , Haiyi Zhong , Haowen Guo , Junjun Ni
Eco-geotechnical engineering plays a pivotal role in enhancing global sustainability and upholding the performance of earthen structures. The utilization of vegetation to stabilise geotechnical infrastructures is widely recognized and embraced for its environmentally friendly attributes. The spectre of climate change further intensifies the focus on the effects of temperature and humidity on vegetated soil. Consequently, there is a pressing need for research exploring the influence of changing climates on vegetated infrastructures. Such research demands a holistic and interdisciplinary approach, bridging fields such as soil mechanics, botany, and atmospheric science. This review underscores key facets crucial to vegetated geotechnical infrastructures, encompassing climate projections, centrifuge modelling, field monitoring, and numerical methodologies.
{"title":"Climate impacts on deformation and instability of vegetated slopes","authors":"Qi Zhang , Haiyi Zhong , Haowen Guo , Junjun Ni","doi":"10.1016/j.bgtech.2024.100139","DOIUrl":"10.1016/j.bgtech.2024.100139","url":null,"abstract":"<div><div>Eco-geotechnical engineering plays a pivotal role in enhancing global sustainability and upholding the performance of earthen structures. The utilization of vegetation to stabilise geotechnical infrastructures is widely recognized and embraced for its environmentally friendly attributes. The spectre of climate change further intensifies the focus on the effects of temperature and humidity on vegetated soil. Consequently, there is a pressing need for research exploring the influence of changing climates on vegetated infrastructures. Such research demands a holistic and interdisciplinary approach, bridging fields such as soil mechanics, botany, and atmospheric science. This review underscores key facets crucial to vegetated geotechnical infrastructures, encompassing climate projections, centrifuge modelling, field monitoring, and numerical methodologies.</div></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"3 2","pages":"Article 100139"},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143697753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-07DOI: 10.1016/j.bgtech.2024.100136
Xiangwei Fang , Chao Chen , Ganggang Zhou , Zhixiong Chen , Chunyan Wang , Luqi Wang
The biocemented coral sand pile composite foundation represents an innovative foundation improvement technology, utilizing Microbially Induced Carbonate Precipitation (MICP) to consolidate a specific volume of coral sand within the foundation into piles with defined strength, thereby enabling them to collaboratively bear external loads with the surrounding unconsolidated coral sand. In this study, a series of shaking table model tests were conducted to explore the dynamic response of the biocemented coral sand pile composite foundation under varying seismic wave types and peak accelerations. The surface macroscopic phenomena, excess pore water pressure ratio, acceleration response, and vertical settlement were measured and analysed in detail. Test results show that seismic wave types play a decisive role in the macroscopic surface phenomena and the response of the excess pore water pressure ratio. The cumulative settlement of the upper structure under the action of Taft waves was about 1.5 times that of El Centro waves and Kobe waves. The most pronounced liquefaction phenomena were recorded under the Taft wave, followed by the El Centro wave, and subsequently the Kobe wave. An observed positive correlation was established between the liquefaction phenomenon and the Aristotelian intensity of the seismic waves. However, variations in seismic wave types exerted minimal influence on the acceleration amplification factor of the coral sand foundation. Analysis of the acceleration amplification factor revealed a triphasic pattern—initially increasing, subsequently decreasing, and finally increasing again—as burial depth increased, in relation to the peak value of the input acceleration. This study confirms that the biocemented coral sand pile composite foundation can effectively enhance the liquefaction resistance of coral sand foundations.
{"title":"Experimental investigation on response of biocemented coral sand pile composite foundation under seismic waves","authors":"Xiangwei Fang , Chao Chen , Ganggang Zhou , Zhixiong Chen , Chunyan Wang , Luqi Wang","doi":"10.1016/j.bgtech.2024.100136","DOIUrl":"10.1016/j.bgtech.2024.100136","url":null,"abstract":"<div><div>The biocemented coral sand pile composite foundation represents an innovative foundation improvement technology, utilizing Microbially Induced Carbonate Precipitation (MICP) to consolidate a specific volume of coral sand within the foundation into piles with defined strength, thereby enabling them to collaboratively bear external loads with the surrounding unconsolidated coral sand. In this study, a series of shaking table model tests were conducted to explore the dynamic response of the biocemented coral sand pile composite foundation under varying seismic wave types and peak accelerations. The surface macroscopic phenomena, excess pore water pressure ratio, acceleration response, and vertical settlement were measured and analysed in detail. Test results show that seismic wave types play a decisive role in the macroscopic surface phenomena and the response of the excess pore water pressure ratio. The cumulative settlement of the upper structure under the action of Taft waves was about 1.5 times that of El Centro waves and Kobe waves. The most pronounced liquefaction phenomena were recorded under the Taft wave, followed by the El Centro wave, and subsequently the Kobe wave. An observed positive correlation was established between the liquefaction phenomenon and the Aristotelian intensity of the seismic waves. However, variations in seismic wave types exerted minimal influence on the acceleration amplification factor of the coral sand foundation. Analysis of the acceleration amplification factor revealed a triphasic pattern—initially increasing, subsequently decreasing, and finally increasing again—as burial depth increased, in relation to the peak value of the input acceleration. This study confirms that the biocemented coral sand pile composite foundation can effectively enhance the liquefaction resistance of coral sand foundations.</div></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"3 2","pages":"Article 100136"},"PeriodicalIF":0.0,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143697652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-31DOI: 10.1016/j.bgtech.2024.100138
Min Kyung Jeon , Matthew Burrall , Tae Hyuk Kwon , Jason T. DeJong , Alejandro Martinez
Characterizing the architecture of tree root systems is essential to advance the development of root-inspired anchorage in engineered systems. This study explores the structural root architectures of orchard trees to understand the interplays between the mechanical behavior of roots and the root architecture. Full three-dimensional (3D) models of natural tree root systems, Lovell, Marianna, and Myrobalan, that were extracted from the ground by vertical pullout are reconstructed through photogrammetry and later skeletonized as nodes and root branch segments. Combined analyses of the full 3D models and skeletonized models enable a detailed examination of basic bulk properties and quantification of architectural parameters. While the root segments are divided into three categories, trunk root, main lateral root, and remaining roots, the patterns in branching and diameter distributions show significant differences between the trunk and main laterals versus the remaining lateral roots. In general, the branching angle decreases over the sequence of bifurcations. The main lateral roots near the trunk show significant spreading while the lateral roots near the ends grow roughly parallel to the parent root. For branch length, the roots bifurcate more frequently near the trunk and later they grow longer. Local thickness analysis confirms that the root diameter decays at a higher rate near the trunk than in the remaining lateral roots, while the total cross-sectional area across a bifurcation node remains mostly conserved. The histograms of branching angle, and branch length and thickness gradient can be described using lognormal and exponential distributions, respectively. This unique study presents data to characterize mechanically important structural roots, which may help link root architecture to the mechanical behaviors of root structures.
{"title":"Architecture characterization of orchard trees for mechanical behavior investigations","authors":"Min Kyung Jeon , Matthew Burrall , Tae Hyuk Kwon , Jason T. DeJong , Alejandro Martinez","doi":"10.1016/j.bgtech.2024.100138","DOIUrl":"10.1016/j.bgtech.2024.100138","url":null,"abstract":"<div><div>Characterizing the architecture of tree root systems is essential to advance the development of root-inspired anchorage in engineered systems. This study explores the structural root architectures of orchard trees to understand the interplays between the mechanical behavior of roots and the root architecture. Full three-dimensional (3D) models of natural tree root systems, Lovell, Marianna, and Myrobalan, that were extracted from the ground by vertical pullout are reconstructed through photogrammetry and later skeletonized as nodes and root branch segments. Combined analyses of the full 3D models and skeletonized models enable a detailed examination of basic bulk properties and quantification of architectural parameters. While the root segments are divided into three categories, trunk root, main lateral root, and remaining roots, the patterns in branching and diameter distributions show significant differences between the trunk and main laterals versus the remaining lateral roots. In general, the branching angle decreases over the sequence of bifurcations. The main lateral roots near the trunk show significant spreading while the lateral roots near the ends grow roughly parallel to the parent root. For branch length, the roots bifurcate more frequently near the trunk and later they grow longer. Local thickness analysis confirms that the root diameter decays at a higher rate near the trunk than in the remaining lateral roots, while the total cross-sectional area across a bifurcation node remains mostly conserved. The histograms of branching angle, and branch length and thickness gradient can be described using lognormal and exponential distributions, respectively. This unique study presents data to characterize mechanically important structural roots, which may help link root architecture to the mechanical behaviors of root structures.</div></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"3 2","pages":"Article 100138"},"PeriodicalIF":0.0,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143697750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bio-mediated soil improvement methods keep on gaining the attention of geotechnical engineers and researchers globally due to their nature-based elegance and eco-friendliness. Most prevalent bio-mediated soil improvement methods include microbially induced carbonate precipitation (MICP) and enzyme-induced carbonate precipitation (EICP). During their processes, the bacteria/free urease hydrolyzes the urea into ammonium and carbonic acid, which is accompanied by a considerable increase of alkalinity (about pH 9.0). The major problem associated with the above techniques is the release of gaseous ammonia that is extremely detrimental. Therefore, this study aims to propose a new sustainable approach involving lactic acid bacteria to facilitate the calcium phosphate mineralization for the strengthening of sand matrix. The major objectives of this investigation are: (i) to evaluate the urease activity of the lactic acid bacteria under different temperatures, pH conditions and additions of metal ions, (ii) to assess the treated sand matrix, (iii) to perform cost analysis. The outcomes indicated that Limosilactobacillus sp. could effectively facilitate the urea hydrolysis, hence increasing the pH from acidic to neutral and providing a desirable environment for the calcium phosphate to mineralize within the voids of the sand. The addition of 0.01 % Ni2+ in culture media was found to enhance the urease activity by 38.8 % and compressive strength over 40 %. A combined formation of amorphous- and whisker-like precipitates could bridge a larger area at particle-particle contact points, thereby faciliating a strong force-network in sand matrix. The mineralized calcium phosphate compound was found to be brushite. The cost herein for producing 1 L treatment solution was estimated to be about 2.5-folds and 11.8-folds lower compared to that of MICP and EICP treatment solutions, respectively. Moreover, since the treatment pH could potentially be regulated between acidic-neural range, it would greatly control the release of gaseous ammonia. With several environmental and economical benefits, the study has disclosed a new sustainable direction for sand improvement via the use of lactic acid bacteria.
{"title":"Proposing a new sustainable approach for sand improvement using biologically-derived calcium phosphate cement","authors":"Sivakumar Gowthaman , Yuta Kumamoto , Kazunori Nakashima , Chikara Takano , Satoru Kawasaki","doi":"10.1016/j.bgtech.2024.100135","DOIUrl":"10.1016/j.bgtech.2024.100135","url":null,"abstract":"<div><div>Bio-mediated soil improvement methods keep on gaining the attention of geotechnical engineers and researchers globally due to their nature-based elegance and eco-friendliness. Most prevalent bio-mediated soil improvement methods include microbially induced carbonate precipitation (MICP) and enzyme-induced carbonate precipitation (EICP). During their processes, the bacteria/free urease hydrolyzes the urea into ammonium and carbonic acid, which is accompanied by a considerable increase of alkalinity (about pH 9.0). The major problem associated with the above techniques is the release of gaseous ammonia that is extremely detrimental. Therefore, this study aims to propose a new sustainable approach involving lactic acid bacteria to facilitate the calcium phosphate mineralization for the strengthening of sand matrix. The major objectives of this investigation are: (i) to evaluate the urease activity of the lactic acid bacteria under different temperatures, pH conditions and additions of metal ions, (ii) to assess the treated sand matrix, (iii) to perform cost analysis. The outcomes indicated that <em>Limosilactobacillus</em> sp. could effectively facilitate the urea hydrolysis, hence increasing the pH from acidic to neutral and providing a desirable environment for the calcium phosphate to mineralize within the voids of the sand. The addition of 0.01 % Ni<sup>2+</sup> in culture media was found to enhance the urease activity by 38.8 % and compressive strength over 40 %. A combined formation of amorphous- and whisker-like precipitates could bridge a larger area at particle-particle contact points, thereby faciliating a strong force-network in sand matrix. The mineralized calcium phosphate compound was found to be brushite. The cost herein for producing 1 L treatment solution was estimated to be about 2.5-folds and 11.8-folds lower compared to that of MICP and EICP treatment solutions, respectively. Moreover, since the treatment pH could potentially be regulated between acidic-neural range, it would greatly control the release of gaseous ammonia. With several environmental and economical benefits, the study has disclosed a new sustainable direction for sand improvement via the use of lactic acid bacteria.</div></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"3 4","pages":"Article 100135"},"PeriodicalIF":0.0,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145230044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Enzyme induced carbonate precipitation (EICP) is a promising technique in the field of biocementation due to its efficiency and controllability. Although many studies have proved its reliability in different environment, little attention has been paid to the influence of humic substances on the EICP. Humic substances cover most of the surface soil across the world land with vegetation, which varies according to the density of vegetation and climate. To understand the compatibility of this technique to distinct problematic soils, it is important to figure out how humic substances could affect the carbonate precipitation process induced by urease enzyme. Therefore, this study aims to investigate the effects of humic acid (HA), one type of humic substance, on the soil solidification through EICP. For this purpose, HA was added to natural soil with varying addition amounts (0%, 1%, 2%, 4%, 8%, 16%) in soil column solidification tests. The results found that the cementation effectiveness was enhanced by a small amount of HA addition (<4%), while an addition up to 8% greatly inhibited the formation of calcium carbonate. At the same time, soil samples were buffered by HA in a weak acidic condition, thus preventing the emission of undesirable by-product ammonia in the ureolysis process. Therefore, this study makes a contribution to research on enzymatic biocementation by demonstrating the effects of HA on the cementation effectiveness of EICP technique.
{"title":"Effect of humic acid on soil solidification by enzyme induced carbonate precipitation","authors":"Meiqi Chen , Aoi Ichinohe , Kazunori Nakashima , Chikara Takano , Sivakumar Gowthaman , Lutfian R. Daryono , Satoru Kawasaki","doi":"10.1016/j.bgtech.2024.100133","DOIUrl":"10.1016/j.bgtech.2024.100133","url":null,"abstract":"<div><div>Enzyme induced carbonate precipitation (EICP) is a promising technique in the field of biocementation due to its efficiency and controllability. Although many studies have proved its reliability in different environment, little attention has been paid to the influence of humic substances on the EICP. Humic substances cover most of the surface soil across the world land with vegetation, which varies according to the density of vegetation and climate. To understand the compatibility of this technique to distinct problematic soils, it is important to figure out how humic substances could affect the carbonate precipitation process induced by urease enzyme. Therefore, this study aims to investigate the effects of humic acid (HA), one type of humic substance, on the soil solidification through EICP. For this purpose, HA was added to natural soil with varying addition amounts (0%, 1%, 2%, 4%, 8%, 16%) in soil column solidification tests. The results found that the cementation effectiveness was enhanced by a small amount of HA addition (<4%), while an addition up to 8% greatly inhibited the formation of calcium carbonate. At the same time, soil samples were buffered by HA in a weak acidic condition, thus preventing the emission of undesirable by-product ammonia in the ureolysis process. Therefore, this study makes a contribution to research on enzymatic biocementation by demonstrating the effects of HA on the cementation effectiveness of EICP technique.</div></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"3 4","pages":"Article 100133"},"PeriodicalIF":0.0,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145229888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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