Pub Date : 2024-10-22DOI: 10.1016/j.bgtech.2024.100131
Kemeng Yu, Yuling Ran, Jie Shi, Menglan Duan, Zhongkun Ouyang
MICP (Microbially induced calcite precipitation), an environmentally friendly soil improvement technique, has great potential in ocean engineering due to its ability to promote the precipitation of calcium carbonate through microbial activity to enhance the engineering properties of geomaterials. In this study, piezocone penetration test (CPTU) is used to evaluate the effectiveness of MICP treatment in calcareous sand. The change of physical properties (relative density Dr and total unit weight γt) of MICP treated calcareous sand is investigated by conducting CPTU on the geomaterials prepared in a series of mini calibration chambers (25 cm × 50 cm). Results indicate that CPTU (tip stress, sleeve friction, and porewater pressure) measurements can be used to interpret the physical characteristics of calcareous sand treated with MICP under seawater conditions. Additionally, a relationship between CPTU measurements, physical parameters (relative density Dr and total unit weight γt) of MICP treated calcareous sand is proposed and calibrated. The findings of the research extend the implementation of in-situ testing techniques such as CPTU towards physical property evaluation of bio-treated geomaterials in ocean environment, and demonstrate the potential of scaling up MICP techniques for broader engineering application.
{"title":"Physical property of MICP-treated calcareous sand under seawater conditions by CPTU","authors":"Kemeng Yu, Yuling Ran, Jie Shi, Menglan Duan, Zhongkun Ouyang","doi":"10.1016/j.bgtech.2024.100131","DOIUrl":"10.1016/j.bgtech.2024.100131","url":null,"abstract":"<div><div>MICP (Microbially induced calcite precipitation), an environmentally friendly soil improvement technique, has great potential in ocean engineering due to its ability to promote the precipitation of calcium carbonate through microbial activity to enhance the engineering properties of geomaterials. In this study, piezocone penetration test (CPTU) is used to evaluate the effectiveness of MICP treatment in calcareous sand. The change of physical properties (relative density <em>D</em><sub>r</sub> and total unit weight <em>γ</em><sub>t</sub>) of MICP treated calcareous sand is investigated by conducting CPTU on the geomaterials prepared in a series of mini calibration chambers (25 cm × 50 cm). Results indicate that CPTU (tip stress, sleeve friction, and porewater pressure) measurements can be used to interpret the physical characteristics of calcareous sand treated with MICP under seawater conditions. Additionally, a relationship between CPTU measurements, physical parameters (relative density <em>D</em><sub>r</sub> and total unit weight <em>γ</em><sub>t</sub>) of MICP treated calcareous sand is proposed and calibrated. The findings of the research extend the implementation of in-situ testing techniques such as CPTU towards physical property evaluation of bio-treated geomaterials in ocean environment, and demonstrate the potential of scaling up MICP techniques for broader engineering application.</div></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"3 1","pages":"Article 100131"},"PeriodicalIF":0.0,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722192","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 : 2024-09-30DOI: 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}
Pub Date : 2024-07-25DOI: 10.1016/j.bgtech.2024.100121
Zhengjun Mao , Xu Ma , Mimi Geng , Munan Wang , Guangsheng Gao , Yanshan Tian
Repeated wet swelling and dry shrinkage of soil leads to the gradual occurrence of cracks and the formation of a complex fracture network. In order to study the development characteristics and quantitative analysis of cracks in root-soil complex in different growth periods under dry-wet cycles, the alfalfa root-loess complex was investigated during different growth periods under different dry-wet cycles, and a dry-wet cycle experiment was conducted. The crack rate, relative area, average width, total length, and the cracks fractal dimension in the root-soil complex were extracted; the crack development characteristics of plain soil were analyzed under the PG-DWC (dry-wet cycle caused by plant water management during plant growth period), as well as the crack development characteristics of root-soil complex under PG-DWC and EC-DWC (the dry-wet cycles caused by extreme natural conditions such as continuous rain); the effects of plant roots and dry-wet cycles on soil cracks were discussed. The results showed that the average crack width, crack rate, relative crack area, and total crack length of the alfalfa root-loess complex were higher than those of the plain soil during PG-DWC. The result indicated that compared with plain soil during PG-DWC, the presence of plant roots in alfalfa root-soil complex in the same growth period promoted the cracks development to some extent. The alfalfa root-soil complex crack parameters during different growth periods were relatively stable during PG-DWC (0 dry-wet cycle). During EC-DWC (1, 3, and 5 dry-wet cycles), the alfalfa root-loess complex crack parameters increased with the number of dry-wet cycles during different growth periods. Unlike PG-DWC, the EC-DWC accelerated crack development, and the degree of crack development increased with the number of dry-wet cycles. The existence of plant roots promoted crack development and expansion in the root-soil complex to a certain extent, and the dry-wet cycle certainly promoted crack development and expansion in the root-soil complex. This result contradicts the improvement in the root-soil complex's macro-mechanical properties during plant growth, due to differences in the mechanical properties of roots and soil. The research results will provide reference for the root soil complex crack development law and the design of slope protection by vegetation.
{"title":"Development characteristics and quantitative analysis of cracks in root-soil complex during different growth periods under dry-wet cycles","authors":"Zhengjun Mao , Xu Ma , Mimi Geng , Munan Wang , Guangsheng Gao , Yanshan Tian","doi":"10.1016/j.bgtech.2024.100121","DOIUrl":"10.1016/j.bgtech.2024.100121","url":null,"abstract":"<div><div>Repeated wet swelling and dry shrinkage of soil leads to the gradual occurrence of cracks and the formation of a complex fracture network. In order to study the development characteristics and quantitative analysis of cracks in root-soil complex in different growth periods under dry-wet cycles, the alfalfa root-loess complex was investigated during different growth periods under different dry-wet cycles, and a dry-wet cycle experiment was conducted. The crack rate, relative area, average width, total length, and the cracks fractal dimension in the root-soil complex were extracted; the crack development characteristics of plain soil were analyzed under the PG-DWC (dry-wet cycle caused by plant water management during plant growth period), as well as the crack development characteristics of root-soil complex under PG-DWC and EC-DWC (the dry-wet cycles caused by extreme natural conditions such as continuous rain); the effects of plant roots and dry-wet cycles on soil cracks were discussed. The results showed that the average crack width, crack rate, relative crack area, and total crack length of the alfalfa root-loess complex were higher than those of the plain soil during PG-DWC. The result indicated that compared with plain soil during PG-DWC, the presence of plant roots in alfalfa root-soil complex in the same growth period promoted the cracks development to some extent. The alfalfa root-soil complex crack parameters during different growth periods were relatively stable during PG-DWC (0 dry-wet cycle). During EC-DWC (1, 3, and 5 dry-wet cycles), the alfalfa root-loess complex crack parameters increased with the number of dry-wet cycles during different growth periods. Unlike PG-DWC, the EC-DWC accelerated crack development, and the degree of crack development increased with the number of dry-wet cycles. The existence of plant roots promoted crack development and expansion in the root-soil complex to a certain extent, and the dry-wet cycle certainly promoted crack development and expansion in the root-soil complex. This result contradicts the improvement in the root-soil complex's macro-mechanical properties during plant growth, due to differences in the mechanical properties of roots and soil. The research results will provide reference for the root soil complex crack development law and the design of slope protection by vegetation.</div></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"3 1","pages":"Article 100121"},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141839789","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 : 2024-07-18DOI: 10.1016/j.bgtech.2024.100123
Xuanshuo Zhang , Hongyu Wang , Ya Wang , Jinghui Wang , Jing Cao , Gang Zhang
Soil improvement is one of the most important issues in geotechnical engineering practice. The wide application of traditional improvement techniques (cement/chemical materials) are limited due to damage ecological environment and intensify carbon emissions. However, the use of microbially induced calcium carbonate precipitation (MICP) to obtain bio-cement is a novel technique with the potential to induce soil stability, providing a low-carbon, environment-friendly, and sustainable integrated solution for some geotechnical engineering problems in the environment. This paper presents a comprehensive review of the latest progress in soil improvement based on the MICP strategy. It systematically summarizes and overviews the mineralization mechanism, influencing factors, improved methods, engineering characteristics, and current field application status of the MICP. Additionally, it also explores the limitations and correspondingly proposes prospective applications via the MICP approach for soil improvement. This review indicates that the utilization of different environmental calcium-based wastes in MICP and combination of materials and MICP are conducive to meeting engineering and market demand. Furthermore, we recommend and encourage global collaborative study and practice with a view to commercializing MICP technique in the future. The current review purports to provide insights for engineers and interdisciplinary researchers, and guidance for future engineering applications.
{"title":"Improved methods, properties, applications and prospects of microbial induced carbonate precipitation (MICP) treated soil: A review","authors":"Xuanshuo Zhang , Hongyu Wang , Ya Wang , Jinghui Wang , Jing Cao , Gang Zhang","doi":"10.1016/j.bgtech.2024.100123","DOIUrl":"10.1016/j.bgtech.2024.100123","url":null,"abstract":"<div><div>Soil improvement is one of the most important issues in geotechnical engineering practice. The wide application of traditional improvement techniques (cement/chemical materials) are limited due to damage ecological environment and intensify carbon emissions. However, the use of microbially induced calcium carbonate precipitation (MICP) to obtain bio-cement is a novel technique with the potential to induce soil stability, providing a low-carbon, environment-friendly, and sustainable integrated solution for some geotechnical engineering problems in the environment. This paper presents a comprehensive review of the latest progress in soil improvement based on the MICP strategy. It systematically summarizes and overviews the mineralization mechanism, influencing factors, improved methods, engineering characteristics, and current field application status of the MICP. Additionally, it also explores the limitations and correspondingly proposes prospective applications via the MICP approach for soil improvement. This review indicates that the utilization of different environmental calcium-based wastes in MICP and combination of materials and MICP are conducive to meeting engineering and market demand. Furthermore, we recommend and encourage global collaborative study and practice with a view to commercializing MICP technique in the future. The current review purports to provide insights for engineers and interdisciplinary researchers, and guidance for future engineering applications.</div></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"3 1","pages":"Article 100123"},"PeriodicalIF":0.0,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141853611","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 : 2024-07-17DOI: 10.1016/j.bgtech.2024.100130
Hanlong Liu
With the increasing demand for buildings and infrastructures and the mounting challenges associated with the current construction technologies such as high emission, high pollution, and high energy consumption, the civil engineering profession is at the crossroad for a transformation or upgrading before it can be put into tasks for these challenges. Inspired by the concept of harmonious coexistence between humans and nature, a new concept, biogenic construction, for civil engineering is proposed in this paper. The definition of biogenic construction is given. The framework and four components of biogenic construction are established. These include microbial construction, plant construction, animal construction, and bioinspired construction. Examples of each component are given. A new construction system for creating a more eco-friendly, healthier, and more sustainable environment for future civil engineering developments is also proposed.
{"title":"Biogenic construction: The new era of civil engineering","authors":"Hanlong Liu","doi":"10.1016/j.bgtech.2024.100130","DOIUrl":"10.1016/j.bgtech.2024.100130","url":null,"abstract":"<div><div>With the increasing demand for buildings and infrastructures and the mounting challenges associated with the current construction technologies such as high emission, high pollution, and high energy consumption, the civil engineering profession is at the crossroad for a transformation or upgrading before it can be put into tasks for these challenges. Inspired by the concept of harmonious coexistence between humans and nature, a new concept, biogenic construction, for civil engineering is proposed in this paper. The definition of biogenic construction is given. The framework and four components of biogenic construction are established. These include microbial construction, plant construction, animal construction, and bioinspired construction. Examples of each component are given. A new construction system for creating a more eco-friendly, healthier, and more sustainable environment for future civil engineering developments is also proposed.</div></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"3 1","pages":"Article 100130"},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141842243","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 : 2024-07-02DOI: 10.1016/j.bgtech.2024.100101
Pei Tai , Fan Wu , Bohan Bai , Zhaofeng Li , Rui Chen , Lulu Zhang
The understanding of rainfall-induced landslides on gentle, loose-fill slopes is limited in comparison to steep slopes. Hence, two physical model tests were conducted on silty sand slopes under continuous rainfall: one on a bare slope and the other on a slope planted with ryegrass. The slope angle of 25° is much lower than the internal friction angle of slope material (34.3°), which makes the model test fall well into the category of gentle slope. For the initially unsaturated bare slope, a rainfall event with return period of 18 years could trigger a rapid and retrogressive global sliding, which differs from previous findings that gentle slopes would only experience shallow failure. A sudden increase in pore-water pressure was simultaneously observed, which might be generated by the wetting-induced collapse of unsaturated loose soil. On the other hand, the stability of the slope with grass plantation was significantly enhanced, and it was able to withstand rainfall event more severe than those with a return period of 100 years, with only minimal deformation. The results suggest that the gain in shear strength due to ryegrass roots surpasses the additional sliding force caused by the increased water retention capability. Additionally, it is found that the abrupt change in pore pressure was no longer indicative of slope failure in the case of the grass-reinforced slope.
{"title":"Influence of grass plantation on the rainfall-induced instability of gentle loose fill slope","authors":"Pei Tai , Fan Wu , Bohan Bai , Zhaofeng Li , Rui Chen , Lulu Zhang","doi":"10.1016/j.bgtech.2024.100101","DOIUrl":"10.1016/j.bgtech.2024.100101","url":null,"abstract":"<div><p>The understanding of rainfall-induced landslides on gentle, loose-fill slopes is limited in comparison to steep slopes. Hence, two physical model tests were conducted on silty sand slopes under continuous rainfall: one on a bare slope and the other on a slope planted with ryegrass. The slope angle of 25° is much lower than the internal friction angle of slope material (34.3°), which makes the model test fall well into the category of gentle slope. For the initially unsaturated bare slope, a rainfall event with return period of 18 years could trigger a rapid and retrogressive global sliding, which differs from previous findings that gentle slopes would only experience shallow failure. A sudden increase in pore-water pressure was simultaneously observed, which might be generated by the wetting-induced collapse of unsaturated loose soil. On the other hand, the stability of the slope with grass plantation was significantly enhanced, and it was able to withstand rainfall event more severe than those with a return period of 100 years, with only minimal deformation. The results suggest that the gain in shear strength due to ryegrass roots surpasses the additional sliding force caused by the increased water retention capability. Additionally, it is found that the abrupt change in pore pressure was no longer indicative of slope failure in the case of the grass-reinforced slope.</p></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"2 4","pages":"Article 100101"},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2949929124000330/pdfft?md5=e559eef248da6ada511b94e9ec23f693&pid=1-s2.0-S2949929124000330-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141691018","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 : 2024-06-29DOI: 10.1016/j.bgtech.2024.100104
Peihao Zhang , Guangyan Xing , Xiasong Hu , Changyi Liu , Xilai Li , Jimei Zhao , Jiangtao Fu , Haijing Lu , Huatan Li , Zhe Zhou , Lei Yue , Yabin Liu , Guorong Li , Haili Zhu
In order to study the infiltration characteristics of grassland soil in the super large scale landslides distribution area in the upper reaches of the Yellow River, this study selected the Xiazangtan super large scale distribution area in Jianzha County as the study area. Through experiments and numerical simulations, plant roots characteristics, soil physical properties and infiltration characteristics of naturally grazed grassland and enclosed grassland with different slope directions were compared and analyzed, and the influence of rainfall on seepage field and stability of the two grassland slopes were discussed. The results show that the highest soil moisture infiltration capacity (FIR) is found on the shady slope of the enclosed grassland (2.25), followed by the sunny slope of the enclosed grassland (1.23) and the shady slope of the naturally grazed grassland (−0.87). Correlation analysis show that soil water content, root dry weight density, total soil porosity, number of forks and root length are positively correlated with infiltration rate (P＜0.05), whereas soil dry density is negatively correlated with infiltration rate (P＜0.05). The results of stepwise regression analyses show that soil water content, total soil porosity, root length and number of forks are the main factors affecting soil infiltration capacity. And the ability of roots to increase soil infiltration by improving soil properties is higher than the effect of roots itself. After 60 min of simulated rainfall, the safety factors of the shady slopes of naturally grazed grassland and enclosed grassland are reduced by 29.56% and 19.63%, respectively, comparing to those before rainfall. Therefore, in this study, the roots play a crucial role in regulating soil infiltration and enhance slope stability by increasing soil water content, soil total porosity and shear strength while decreasing soil dry density. The results of this study provide theoretical evidence and practical guidance for the effective prevention and control of secondary geological disasters such as soil erosion and shallow landslide on the slope of river banks in the study area by using plant ecological measures.
{"title":"Effects of grassland vegetation roots on soil infiltration rate in Xiazangtan super large scale landslide distribution area in the upper reaches of the Yellow River, China","authors":"Peihao Zhang , Guangyan Xing , Xiasong Hu , Changyi Liu , Xilai Li , Jimei Zhao , Jiangtao Fu , Haijing Lu , Huatan Li , Zhe Zhou , Lei Yue , Yabin Liu , Guorong Li , Haili Zhu","doi":"10.1016/j.bgtech.2024.100104","DOIUrl":"10.1016/j.bgtech.2024.100104","url":null,"abstract":"<div><p>In order to study the infiltration characteristics of grassland soil in the super large scale landslides distribution area in the upper reaches of the Yellow River, this study selected the Xiazangtan super large scale distribution area in Jianzha County as the study area. Through experiments and numerical simulations, plant roots characteristics, soil physical properties and infiltration characteristics of naturally grazed grassland and enclosed grassland with different slope directions were compared and analyzed, and the influence of rainfall on seepage field and stability of the two grassland slopes were discussed. The results show that the highest soil moisture infiltration capacity (FIR) is found on the shady slope of the enclosed grassland (2.25), followed by the sunny slope of the enclosed grassland (1.23) and the shady slope of the naturally grazed grassland (−0.87). Correlation analysis show that soil water content, root dry weight density, total soil porosity, number of forks and root length are positively correlated with infiltration rate (<em>P</em>＜0.05), whereas soil dry density is negatively correlated with infiltration rate (<em>P</em>＜0.05). The results of stepwise regression analyses show that soil water content, total soil porosity, root length and number of forks are the main factors affecting soil infiltration capacity. And the ability of roots to increase soil infiltration by improving soil properties is higher than the effect of roots itself. After 60 min of simulated rainfall, the safety factors of the shady slopes of naturally grazed grassland and enclosed grassland are reduced by 29.56% and 19.63%, respectively, comparing to those before rainfall. Therefore, in this study, the roots play a crucial role in regulating soil infiltration and enhance slope stability by increasing soil water content, soil total porosity and shear strength while decreasing soil dry density. The results of this study provide theoretical evidence and practical guidance for the effective prevention and control of secondary geological disasters such as soil erosion and shallow landslide on the slope of river banks in the study area by using plant ecological measures.</p></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"2 4","pages":"Article 100104"},"PeriodicalIF":0.0,"publicationDate":"2024-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2949929124000366/pdfft?md5=32eff534fe5d0bbb5e86dc6c67130180&pid=1-s2.0-S2949929124000366-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141953117","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 : 2024-06-21DOI: 10.1016/j.bgtech.2024.100102
Mary C. Ngoma , Oladoyin Kolawole
Biocementation is an emerging field within geotechnical engineering that focuses on harnessing microbiological activity to enhance the mechanical properties and behavior of rocks. It often relies on microbial-induced carbonate precipitation (MICP) or enzyme-induced carbonate precipitation (EICP) which utilizes biomineralization by promoting the generation of calcium carbonate (CaCO3) within the pores of geomaterials (rock and soil). However, there is still a lack of knowledge about the effect of porosity and bedding on biocementation in rocks from a mechanistic view. This experimental study investigated the impact of porosity and bedding orientations on the mechanical response of rocks due to biocementations, using two distinct biocementation strategies (MICP and EICP) and characteristically low porosity but interbedded rocks (shale) and more porous but non-bedded (dolostone) rocks. We first conducted biocementation treatments (MICP and EICP) of rock samples over a distinct period and temperature. Subsequently, the rock strength (uniaxial compressive strength, UCS) was measured. Finally, we analyzed the pre- and post-treatment changes in the rock samples to better understand the effect of MICP and EICP biocementations on the mechanical response of the rock samples. The results indicate that biocementations in dolostones can improve the rock mechanical integrity (EICP: +58% UCS; MICP: +25% UCS). In shales, biocementations can either slightly improve (EICP: +1% UCS) or weaken the rock mechanical integrity (MICP: −39% UCS). Further, results suggest that the major controlling mechanisms of biogeomechanical alterations due to MICP and EICP in rocks can be attributed to the inherent porosity, biocementation type, and bedding orientations, and in few cases the mechanisms can be swelling, osmotic suction, or pore pressurization. The findings in this study provide novel insights into the mechanical responses of rocks due to MICP and EICP biocementations.
{"title":"Porosity and bedding controls on bio-induced carbonate precipitation and mechanical properties of shale and dolomitic rocks: EICP vs MICP","authors":"Mary C. Ngoma , Oladoyin Kolawole","doi":"10.1016/j.bgtech.2024.100102","DOIUrl":"10.1016/j.bgtech.2024.100102","url":null,"abstract":"<div><p>Biocementation is an emerging field within geotechnical engineering that focuses on harnessing microbiological activity to enhance the mechanical properties and behavior of rocks. It often relies on microbial-induced carbonate precipitation (MICP) or enzyme-induced carbonate precipitation (EICP) which utilizes biomineralization by promoting the generation of calcium carbonate (CaCO<sub>3</sub>) within the pores of geomaterials (rock and soil). However, there is still a lack of knowledge about the effect of porosity and bedding on biocementation in rocks from a mechanistic view. This experimental study investigated the impact of porosity and bedding orientations on the mechanical response of rocks due to biocementations, using two distinct biocementation strategies (MICP and EICP) and characteristically low porosity but interbedded rocks (shale) and more porous but non-bedded (dolostone) rocks. We first conducted biocementation treatments (MICP and EICP) of rock samples over a distinct period and temperature. Subsequently, the rock strength (uniaxial compressive strength, <em>UCS</em>) was measured. Finally, we analyzed the pre- and post-treatment changes in the rock samples to better understand the effect of MICP and EICP biocementations on the mechanical response of the rock samples. The results indicate that biocementations in dolostones can improve the rock mechanical integrity (EICP: +58% <em>UCS</em>; MICP: +25% <em>UCS</em>). In shales, biocementations can either slightly improve (EICP: +1% <em>UCS</em>) or weaken the rock mechanical integrity (MICP: −39% <em>UCS</em>)<em>.</em> Further, results suggest that the major controlling mechanisms of biogeomechanical alterations due to MICP and EICP in rocks can be attributed to the inherent porosity, biocementation type, and bedding orientations, and in few cases the mechanisms can be swelling, osmotic suction, or pore pressurization. The findings in this study provide novel insights into the mechanical responses of rocks due to MICP and EICP biocementations.</p></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"2 4","pages":"Article 100102"},"PeriodicalIF":0.0,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2949929124000342/pdfft?md5=1b0d98ae6537e922cb84f6483aae4130&pid=1-s2.0-S2949929124000342-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141953119","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 : 2024-06-04DOI: 10.1016/j.bgtech.2024.100109
Microbially induced calcium carbonate precipitation (MICP) is recognized as a promising technique for soil improvement. The morphological evolution of calcium carbonate (CaCO3) crystals during the MICP process significantly impacts the engineering properties of biocemented soils. However, the morphological changes of CaCO3 precipitates upon bacterial adsorption onto crystal surfaces have not been sufficiently studied. This study employs real-time laser scanning confocal microscopy (LSCM) to simultaneously monitor the dynamics of CaCO3 growth and bacterial attachment during the MICP process, while fluorescence staining is used to differentiate between living and dead bacteria. The results indicate that during the initial stage of the MICP process, the predominant morphology of the CaCO3 crystals was elliptical, with a minor fraction exhibiting a rhombohedral morphology. Over time, additional elliptical crystals gradually formed around the existing elliptical ones. As the crystals grew, certain bacteria in the vicinity of the crystals became adsorbed onto their surfaces, irrespective of bacterial viability. However, bacterial adsorption did not alter the morphology of the crystals. The study provides microscale insights into the mechanisms of bacterial attachment to CaCO3 crystals during biomineralization.
{"title":"Bacterial attachment by crystal in MICP","authors":"","doi":"10.1016/j.bgtech.2024.100109","DOIUrl":"10.1016/j.bgtech.2024.100109","url":null,"abstract":"<div><p>Microbially induced calcium carbonate precipitation (MICP) is recognized as a promising technique for soil improvement. The morphological evolution of calcium carbonate (CaCO<sub>3</sub>) crystals during the MICP process significantly impacts the engineering properties of biocemented soils. However, the morphological changes of CaCO<sub>3</sub> precipitates upon bacterial adsorption onto crystal surfaces have not been sufficiently studied. This study employs real-time laser scanning confocal microscopy (LSCM) to simultaneously monitor the dynamics of CaCO<sub>3</sub> growth and bacterial attachment during the MICP process, while fluorescence staining is used to differentiate between living and dead bacteria. The results indicate that during the initial stage of the MICP process, the predominant morphology of the CaCO<sub>3</sub> crystals was elliptical, with a minor fraction exhibiting a rhombohedral morphology. Over time, additional elliptical crystals gradually formed around the existing elliptical ones. As the crystals grew, certain bacteria in the vicinity of the crystals became adsorbed onto their surfaces, irrespective of bacterial viability. However, bacterial adsorption did not alter the morphology of the crystals. The study provides microscale insights into the mechanisms of bacterial attachment to CaCO<sub>3</sub> crystals during biomineralization.</p></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"2 4","pages":"Article 100109"},"PeriodicalIF":0.0,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S294992912400041X/pdfft?md5=04dc589473fd579fb1f42bd12411b0c2&pid=1-s2.0-S294992912400041X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141391812","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 : 2024-06-03DOI: 10.1016/j.bgtech.2024.100110
Yu Diao , Jitao Bai , Gang Zheng , Qingsong Hu , Pengjin Li , Xuanqi Liu , Wendi Hu , Jianyou Huang
With further investigation on biomineralization, biomimetic mineralization has been proposed in imitation of microorganism behavior, in which the mechanism of biomineralization is utilized for the control of the crystal growth to synthesize inorganic materials with special structures and superior physical-chemical properties. This review summarizes the recent advances in biomimetic-chemically induced carbonate precipitation (BCICP). BCICP is a biomimetic mineralization process induced by calcium carbonate crystal modifiers, which directly regulates the metathesis reaction of calcium salts with carbonates in soils to improve the soil properties. Several crystal modifiers for BCICP, including the aspartic acid (organic), the boric acid (inorganic), and the polyacrylic acid (polymer), are reviewed, and the biomimetic mineralization mechanism is introduced. In addition, current findings about BCICP in cementitious materials, soil reinforcement, dust suppression, as well as other fields are discussed, aiming to give deeper insights into the further development and application of BCICP.
{"title":"Development and optimization of biomimetic-chemically induced carbonate precipitation: A review of recent research","authors":"Yu Diao , Jitao Bai , Gang Zheng , Qingsong Hu , Pengjin Li , Xuanqi Liu , Wendi Hu , Jianyou Huang","doi":"10.1016/j.bgtech.2024.100110","DOIUrl":"10.1016/j.bgtech.2024.100110","url":null,"abstract":"<div><div>With further investigation on biomineralization, biomimetic mineralization has been proposed in imitation of microorganism behavior, in which the mechanism of biomineralization is utilized for the control of the crystal growth to synthesize inorganic materials with special structures and superior physical-chemical properties. This review summarizes the recent advances in biomimetic-chemically induced carbonate precipitation (BCICP). BCICP is a biomimetic mineralization process induced by calcium carbonate crystal modifiers, which directly regulates the metathesis reaction of calcium salts with carbonates in soils to improve the soil properties. Several crystal modifiers for BCICP, including the aspartic acid (organic), the boric acid (inorganic), and the polyacrylic acid (polymer), are reviewed, and the biomimetic mineralization mechanism is introduced. In addition, current findings about BCICP in cementitious materials, soil reinforcement, dust suppression, as well as other fields are discussed, aiming to give deeper insights into the further development and application of BCICP.</div></div>","PeriodicalId":100175,"journal":{"name":"Biogeotechnics","volume":"3 1","pages":"Article 100110"},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141279618","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}
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