Pub Date : 2023-08-07DOI: 10.3390/geotechnics3030041
Ahmed Bukhary, S. Azam
Severe climatic and environmental conditions warrant the use of stabilization agents in aid of compaction for sustainable improvement in engineering properties of clays. Physicochemical agents are a viable option because they are cost effective, environmentally friendly, and offer improved long-term performance of treated soils. This research developed a fundamental understanding of the clay–water–electrolyte admixtures relations. Based on a comprehensive literature review, the effect of nanomaterials, biopolymers, and geopolymers on the behavior of compacted clays was investigated. It was found that all of these admixtures facilitate the development of an aggregated soil microstructure through unique mechanisms. Biopolymers have the highest water adsorption capacity followed by geopolymers and then by nanomaterials. The effect of admixtures on optimum compaction properties follows a decreasing trend similar to untreated clays (S = 80% ± 20%). The variation of hydraulic conductivity, compression index, and compressive strength are largely within the family of curves identified by typical relationships for compacted clays. These preliminary findings indicate that not all engineering properties are improved to the same level by the different types of physicochemical admixtures. The specific nature of geotechnical engineering (soil type and site conditions) as well as the wide range of admixture types and potential biodegradation of some of the reagents are the major shortcoming of using this class of materials.
{"title":"A Review of Physicochemical Stabilization for Improved Engineering Properties of Clays","authors":"Ahmed Bukhary, S. Azam","doi":"10.3390/geotechnics3030041","DOIUrl":"https://doi.org/10.3390/geotechnics3030041","url":null,"abstract":"Severe climatic and environmental conditions warrant the use of stabilization agents in aid of compaction for sustainable improvement in engineering properties of clays. Physicochemical agents are a viable option because they are cost effective, environmentally friendly, and offer improved long-term performance of treated soils. This research developed a fundamental understanding of the clay–water–electrolyte admixtures relations. Based on a comprehensive literature review, the effect of nanomaterials, biopolymers, and geopolymers on the behavior of compacted clays was investigated. It was found that all of these admixtures facilitate the development of an aggregated soil microstructure through unique mechanisms. Biopolymers have the highest water adsorption capacity followed by geopolymers and then by nanomaterials. The effect of admixtures on optimum compaction properties follows a decreasing trend similar to untreated clays (S = 80% ± 20%). The variation of hydraulic conductivity, compression index, and compressive strength are largely within the family of curves identified by typical relationships for compacted clays. These preliminary findings indicate that not all engineering properties are improved to the same level by the different types of physicochemical admixtures. The specific nature of geotechnical engineering (soil type and site conditions) as well as the wide range of admixture types and potential biodegradation of some of the reagents are the major shortcoming of using this class of materials.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"30 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81149316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Prithvendra Singh, C. Vitone, B. Baudet, F. Cotecchia, M. Notarnicola, M. Plötze, A. Puzrin, Venkata Siva Naga Sai Goli, M. Mali, Rosella Petti, F. Sollecito, F. Todaro, Abdulla Muththalib, A. Mohammad, Mrunal S Bokade, Devendra Singh
The constraints associated with the availability of huge amounts of natural resources for infrastructure and agricultural development calls for the reuse and recycling of anthropogenically created geomaterials, which is in line with the UN Sustainable Development Goals. In this context, valorization of dredged sediments (DS), obtained from water bodies such as rivers, lakes, oceans, etc., as a resource material is worth considering. Unfortunately, DS might be contaminated and exhibit a higher moisture-holding capacity due to higher organic matter and clay minerals/colloids. These attributes pose a serious question towards dumping of the DS in the deep sea (in the case of marine sediments), a practice which though prevails presently but endangers marine life. Hence, the way forward would be to characterize them holistically, followed by adequate treatment to make them ecologically synergetic before developing a strategy for their valorization. In this regard, many studies have been focused on the characterization and treatment of DS to make them environmentally safe manmade resource. With this in view, a critical synthesis of the published literature pertaining to the (i) characterization, (ii) treatment, remediation, and immobilization of contaminants, and (iii) utilization of DS has been conducted, and the salient findings are presented in this paper. Based on this study, it was observed that the DS acts as a sink for emerging contaminants for which no remediation strategies are available. Moreover, the study highlighted the lacuna in upscaling the existing treatment and stabilization techniques to field conditions while highlighting the concept of circular economy.
{"title":"Characterization, remediation and valorization of contaminated sediments – a critical review","authors":"Prithvendra Singh, C. Vitone, B. Baudet, F. Cotecchia, M. Notarnicola, M. Plötze, A. Puzrin, Venkata Siva Naga Sai Goli, M. Mali, Rosella Petti, F. Sollecito, F. Todaro, Abdulla Muththalib, A. Mohammad, Mrunal S Bokade, Devendra Singh","doi":"10.1680/jenge.22.00201","DOIUrl":"https://doi.org/10.1680/jenge.22.00201","url":null,"abstract":"The constraints associated with the availability of huge amounts of natural resources for infrastructure and agricultural development calls for the reuse and recycling of anthropogenically created geomaterials, which is in line with the UN Sustainable Development Goals. In this context, valorization of dredged sediments (DS), obtained from water bodies such as rivers, lakes, oceans, etc., as a resource material is worth considering. Unfortunately, DS might be contaminated and exhibit a higher moisture-holding capacity due to higher organic matter and clay minerals/colloids. These attributes pose a serious question towards dumping of the DS in the deep sea (in the case of marine sediments), a practice which though prevails presently but endangers marine life. Hence, the way forward would be to characterize them holistically, followed by adequate treatment to make them ecologically synergetic before developing a strategy for their valorization. In this regard, many studies have been focused on the characterization and treatment of DS to make them environmentally safe manmade resource. With this in view, a critical synthesis of the published literature pertaining to the (i) characterization, (ii) treatment, remediation, and immobilization of contaminants, and (iii) utilization of DS has been conducted, and the salient findings are presented in this paper. Based on this study, it was observed that the DS acts as a sink for emerging contaminants for which no remediation strategies are available. Moreover, the study highlighted the lacuna in upscaling the existing treatment and stabilization techniques to field conditions while highlighting the concept of circular economy.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46626541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-02DOI: 10.3390/geotechnics3030040
Yaniv Darvasi, A. Agnon
Conventional geophysical methods are suitable for estimating the thicknesses of subsoil layers. By combining several geophysical methods, the uncertainties can be assessed. Hence, the reliability of the results increases with a more accurate engineering solution. To estimate the base of an abandoned landfill, we collected data using classical approaches: high-resolution seismic reflection and refraction, with more modern methods including passive surface wave analysis and horizontal-to-vertical spectral ratio (HVSR) measurements. To evaluate the thickness of the landfill, three different datasets were acquired along each of the two seismic lines, and five different processing methods were applied for each of the two arrays. The results of all the classical methods indicate very consistent correlations and mostly converge to clear outcomes. However, since the shear wave velocity of the landfill is relatively low (<150 (m/s)), the uncertainty of the HVSR results is significant. All these methods are engineering-oriented, environmentally friendly, and relatively low-cost. They may be jointly interpreted to better assess uncertainties and therefore enable an efficient solution for environmental or engineering purposes.
{"title":"Estimation of Low-Velocity Landfill Thickness with Multi-Method Seismic Surveys","authors":"Yaniv Darvasi, A. Agnon","doi":"10.3390/geotechnics3030040","DOIUrl":"https://doi.org/10.3390/geotechnics3030040","url":null,"abstract":"Conventional geophysical methods are suitable for estimating the thicknesses of subsoil layers. By combining several geophysical methods, the uncertainties can be assessed. Hence, the reliability of the results increases with a more accurate engineering solution. To estimate the base of an abandoned landfill, we collected data using classical approaches: high-resolution seismic reflection and refraction, with more modern methods including passive surface wave analysis and horizontal-to-vertical spectral ratio (HVSR) measurements. To evaluate the thickness of the landfill, three different datasets were acquired along each of the two seismic lines, and five different processing methods were applied for each of the two arrays. The results of all the classical methods indicate very consistent correlations and mostly converge to clear outcomes. However, since the shear wave velocity of the landfill is relatively low (<150 (m/s)), the uncertainty of the HVSR results is significant. All these methods are engineering-oriented, environmentally friendly, and relatively low-cost. They may be jointly interpreted to better assess uncertainties and therefore enable an efficient solution for environmental or engineering purposes.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"14 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79655685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-02DOI: 10.3390/geotechnics3030039
Salvador Navarro Carrasco, José Antonio Jiménez-Valera, I. Alhama
The interaction between groundwater and civil engineering works is a key aspect in geotechnical design. In the case of excavations confined in sheet pile walls, steel sheeting, diaphragm walls, cut-off walls, or cofferdams, this design requires the estimation, among other soil mechanics properties, of the groundwater flowing into the excavation (seepage) caused by piezometry depletion. Numerical methods, graphical solutions, and analytical procedures are the methodologies traditionally used to solve this issue, solutions of which require an understanding of basic soil mechanical properties, hydraulic conditions and structure geometry. In this work, the discriminated non-dimensionalization technique is applied to obtain, for the first time, the dimensionless groups that govern the seepage, in anisotropic conditions, in large-scale scenarios where groundwater flow is not conditioned by impervious bedrock or the length of the back of the wall: π1=ab,π2=kxb2kyc2 and, π3=T/b. Numerical simulations are carried out to check the validity of dimensionless groups and to develop three sets of type curves that relate to these groups. Once the physical and geometrical data are known, the seepage (Q), the characteristic depth (T*) and the characteristic horizontal extension (L*) can be directly and easily calculated from these abacuses. The influence of anisotropy on the characteristic lengths is also addressed.
{"title":"A Universal Graphical Solution to Calculating Seepage in Excavation of Anisotropic Soils and Non-Limited Scenarios","authors":"Salvador Navarro Carrasco, José Antonio Jiménez-Valera, I. Alhama","doi":"10.3390/geotechnics3030039","DOIUrl":"https://doi.org/10.3390/geotechnics3030039","url":null,"abstract":"The interaction between groundwater and civil engineering works is a key aspect in geotechnical design. In the case of excavations confined in sheet pile walls, steel sheeting, diaphragm walls, cut-off walls, or cofferdams, this design requires the estimation, among other soil mechanics properties, of the groundwater flowing into the excavation (seepage) caused by piezometry depletion. Numerical methods, graphical solutions, and analytical procedures are the methodologies traditionally used to solve this issue, solutions of which require an understanding of basic soil mechanical properties, hydraulic conditions and structure geometry. In this work, the discriminated non-dimensionalization technique is applied to obtain, for the first time, the dimensionless groups that govern the seepage, in anisotropic conditions, in large-scale scenarios where groundwater flow is not conditioned by impervious bedrock or the length of the back of the wall: π1=ab,π2=kxb2kyc2 and, π3=T/b. Numerical simulations are carried out to check the validity of dimensionless groups and to develop three sets of type curves that relate to these groups. Once the physical and geometrical data are known, the seepage (Q), the characteristic depth (T*) and the characteristic horizontal extension (L*) can be directly and easily calculated from these abacuses. The influence of anisotropy on the characteristic lengths is also addressed.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"69 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84255564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Vaverková, E. Paleologos, Venkata Siva Naga Sai Goli, E. Koda, A. Mohammad, A. Podlasek, J. Winkler, Aleksandra Jakimiuk, Martin Černý, Devendra Singh
Environmental regulations on landfills contain detailed instructions for the monitoring of pollution from leachate on water, air, and soil. However, references to the impact of landfills on the landscape and the need to monitor the surrounding vegetation are described only in general terms. Studies have indicated that near-surface pollution events, which are not necessarily captured by existing regulatory monitoring schemes, have affected the vegetation in the vicinity of landfills. Indications for the effects of pollution emanating from landfills include the retreat of sensitive and native plant species, the abundance of halophytes or nitrophilous plants, and the prevalence of other invasive plant species, which can spread to adjacent ecosystems. To the best of the authors’ knowledge, a comprehensive synthesis of landfill plant-based biomonitoring results has not yet been reported. The advantage of biomonitoring lies in its ability to assess the quality of the environment as perceived by living organisms. This would facilitate the determination of the response of plants to departures from natural conditions, detection of trends occurring in ecosystems, and adoption of management practices to prevent or mitigate degradation of the environment. Thus, to detect such effects on the flora surrounding a landfill, this article recommends that biomonitoring is utilized in environmental regulations to complement existing monitoring techniques.
{"title":"Landfills’ environmental impacts: perspectives on biomonitoring","authors":"M. Vaverková, E. Paleologos, Venkata Siva Naga Sai Goli, E. Koda, A. Mohammad, A. Podlasek, J. Winkler, Aleksandra Jakimiuk, Martin Černý, Devendra Singh","doi":"10.1680/jenge.23.00003","DOIUrl":"https://doi.org/10.1680/jenge.23.00003","url":null,"abstract":"Environmental regulations on landfills contain detailed instructions for the monitoring of pollution from leachate on water, air, and soil. However, references to the impact of landfills on the landscape and the need to monitor the surrounding vegetation are described only in general terms. Studies have indicated that near-surface pollution events, which are not necessarily captured by existing regulatory monitoring schemes, have affected the vegetation in the vicinity of landfills. Indications for the effects of pollution emanating from landfills include the retreat of sensitive and native plant species, the abundance of halophytes or nitrophilous plants, and the prevalence of other invasive plant species, which can spread to adjacent ecosystems. To the best of the authors’ knowledge, a comprehensive synthesis of landfill plant-based biomonitoring results has not yet been reported. The advantage of biomonitoring lies in its ability to assess the quality of the environment as perceived by living organisms. This would facilitate the determination of the response of plants to departures from natural conditions, detection of trends occurring in ecosystems, and adoption of management practices to prevent or mitigate degradation of the environment. Thus, to detect such effects on the flora surrounding a landfill, this article recommends that biomonitoring is utilized in environmental regulations to complement existing monitoring techniques.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43272493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Totland, Caroline Berge Hansen, A. Nybakk, E. Eek
Remediation activities in polluted sediments, such as dredging and capping, induce the risk of transporting polluted sediments into the water column. Turbidity surveillance is the common method for in situ environmental monitoring during such activities. However, at various stages of the remediation process, the turbidity may be caused by either clean or polluted materials. Here, the potential of using chemical sensors to discriminate between turbidity caused by clean and polluted sediments is evaluated. Dissolved oxygen (DO), turbidity and pH were measured in laboratory tests with suspensions of three different polluted sediments, as well as for two common clean capping materials. Additionally, turbidity, pH and DO were measured during dredging at one of the polluted sites. Whereas turbidity caused by clean materials did not affect pH or DO, there is an inverse linear relationship between DO and turbidity for two of the polluted sediments. Furthermore, for two of the sediments, pH is a strong indicator of sediment resuspension into the water column, with ΔpH>0.5 both in the lab and during dredging in the field. Hence, pH and/or DO surveillance is shown to be potential tools for in situ real-time monitoring of environmental risk during disturbances in polluted sediments.
{"title":"Real-time monitoring of pH and dissolved oxygen during disturbances in polluted sediments","authors":"C. Totland, Caroline Berge Hansen, A. Nybakk, E. Eek","doi":"10.1680/jenge.22.00189","DOIUrl":"https://doi.org/10.1680/jenge.22.00189","url":null,"abstract":"Remediation activities in polluted sediments, such as dredging and capping, induce the risk of transporting polluted sediments into the water column. Turbidity surveillance is the common method for in situ environmental monitoring during such activities. However, at various stages of the remediation process, the turbidity may be caused by either clean or polluted materials. Here, the potential of using chemical sensors to discriminate between turbidity caused by clean and polluted sediments is evaluated. Dissolved oxygen (DO), turbidity and pH were measured in laboratory tests with suspensions of three different polluted sediments, as well as for two common clean capping materials. Additionally, turbidity, pH and DO were measured during dredging at one of the polluted sites. Whereas turbidity caused by clean materials did not affect pH or DO, there is an inverse linear relationship between DO and turbidity for two of the polluted sediments. Furthermore, for two of the sediments, pH is a strong indicator of sediment resuspension into the water column, with ΔpH>0.5 both in the lab and during dredging in the field. Hence, pH and/or DO surveillance is shown to be potential tools for in situ real-time monitoring of environmental risk during disturbances in polluted sediments.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46595385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-24DOI: 10.3390/geotechnics3030038
K. Pakoksung, A. Suppasri, Fumihiko Imamura
This study focuses on understanding the historical tsunami events in Eastern Indonesia, specifically the Banda Sea region, by extracting information from the limited and challenging-to-interpret historical records. The oldest detailed account of a tsunami in Indonesia dates back to 1674, documented in the book Waerachtigh Verhael Van de Schlickelijcke Aerdbebinge by Rumphius. The study aims to comprehend the primary source of the tsunami and analyze its characteristics to facilitate future tsunami risk reduction. The methodology includes collecting topography and bathymetry data, conducting landslide scenario analysis, employing a two-layer wave propagation model, and performing spectral analysis. The study utilizes comprehensive datasets, investigates potential landslide scenarios, simulates tsunami propagation, and analyzes frequency characteristics using the fast Fourier transform. The 1674 event yielded a runup height of approximately 50–100 m, whereas this study underestimated the actual runup. To illustrate the tsunami wave along the bay’s coastline, a Hovmöller diagram was employed. By analyzing the Hovmöller diagram, the power spectral density was computed, revealing five prominent period bands: 6.96, 5.16, 4.1, 3.75, and 3.36 min. The integration of these components provides a rigorous approach to understanding tsunami dynamics and enhancing risk assessment and mitigation in the study area.
本研究的重点是通过从有限且具有挑战性的历史记录中提取信息，了解印度尼西亚东部，特别是班达海地区的历史海啸事件。印尼海啸最古老的详细记录可以追溯到1674年，记录在Rumphius的《Waerachtigh Verhael Van de Schlickelijcke Aerdbebinge》一书中。本研究旨在了解海啸的主要来源，并分析其特征，以促进未来减少海啸风险。方法包括收集地形和测深数据，进行滑坡情景分析，采用两层波传播模型，并进行频谱分析。该研究利用综合数据集，调查潜在的滑坡情景，模拟海啸传播，并使用快速傅里叶变换分析频率特性。1674年的事件产生了大约50-100米的上升高度，而这项研究低估了实际的上升高度。为了说明沿海湾海岸线的海啸波，使用了Hovmöller图表。通过分析Hovmöller图，计算了功率谱密度，揭示了五个突出的周期带:6.96,5.16,4.1,3.75和3.36 min。这些组件的集成为了解海啸动力学和加强研究区域的风险评估和减灾提供了严格的方法。
{"title":"Tsunami Wave Characteristics from the 1674 Ambon Earthquake Event Based on Landslide Scenarios","authors":"K. Pakoksung, A. Suppasri, Fumihiko Imamura","doi":"10.3390/geotechnics3030038","DOIUrl":"https://doi.org/10.3390/geotechnics3030038","url":null,"abstract":"This study focuses on understanding the historical tsunami events in Eastern Indonesia, specifically the Banda Sea region, by extracting information from the limited and challenging-to-interpret historical records. The oldest detailed account of a tsunami in Indonesia dates back to 1674, documented in the book Waerachtigh Verhael Van de Schlickelijcke Aerdbebinge by Rumphius. The study aims to comprehend the primary source of the tsunami and analyze its characteristics to facilitate future tsunami risk reduction. The methodology includes collecting topography and bathymetry data, conducting landslide scenario analysis, employing a two-layer wave propagation model, and performing spectral analysis. The study utilizes comprehensive datasets, investigates potential landslide scenarios, simulates tsunami propagation, and analyzes frequency characteristics using the fast Fourier transform. The 1674 event yielded a runup height of approximately 50–100 m, whereas this study underestimated the actual runup. To illustrate the tsunami wave along the bay’s coastline, a Hovmöller diagram was employed. By analyzing the Hovmöller diagram, the power spectral density was computed, revealing five prominent period bands: 6.96, 5.16, 4.1, 3.75, and 3.36 min. The integration of these components provides a rigorous approach to understanding tsunami dynamics and enhancing risk assessment and mitigation in the study area.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"13 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83587863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-21DOI: 10.3390/geotechnics3030037
José Maria dos Santos Rodrigues Neto, N. Bhandary, Y. Fujita
The rainfall-induced landslide disasters in July 2018 in Southwestern Japan yet again exemplified the severity of slope failure-related damage and the need for improvement of early warning systems. The Japanese Meteorological Agency (JMA) uses a method based on a threshold value of soil water index (SWI), a conceptual measurement that represents saturation of slope soil. The current SWI early warning system uses 60-min rainfall data on a 5-km2 mesh and does not take into consideration other landslide conditioning factors such as slope angle and geology. This study calculates SWI values during the July 2018 disasters in Kure City (Hiroshima Prefecture) using 1-min XRAIN rainfall data in a 250-m mesh to investigate the relationship between SWI and landslide occurrence. It was found that the SWI threshold of 124 mm used in the JMA early warning system for the area was surpassed in all cells. A new SWI threshold calculation method taking slope angle and geology into consideration and produced with machine learning is proposed, comprising power lines for different geological units at a two-dimensional graph where points located above the threshold line represent landslide risk. It is judged that this method would provide a more accurate early warning system for landslide disasters.
2018年7月在日本西南部发生的降雨引发的滑坡灾害再次证明了边坡破坏相关损害的严重性以及改进预警系统的必要性。日本气象厅(JMA)使用了一种基于土壤水指数(SWI)阈值的方法，这是一种代表斜坡土壤饱和度的概念性测量。目前的SWI预警系统采用的是5平方公里网格上60分钟的降雨数据，没有考虑坡角、地质等其他滑坡调节因素。本研究利用250米网1分钟XRAIN降雨数据，计算了2018年7月广岛县Kure市灾害期间的SWI值，探讨了SWI与滑坡发生的关系。结果发现，所有小区均超过了气象厅预警系统中使用的124 mm SWI阈值。提出了一种考虑坡角和地质因素并利用机器学习生成的新的SWI阈值计算方法，该方法在二维图中包含不同地质单元的电力线，位于阈值线上的点代表滑坡风险。该方法可为滑坡灾害提供更为准确的预警系统。
{"title":"An Analytical Study on Soil Water Index (SWI), Landslide Prediction and Other Related Factors Using XRAIN Data during the July 2018 Heavy Rain Disasters in Hiroshima, Japan","authors":"José Maria dos Santos Rodrigues Neto, N. Bhandary, Y. Fujita","doi":"10.3390/geotechnics3030037","DOIUrl":"https://doi.org/10.3390/geotechnics3030037","url":null,"abstract":"The rainfall-induced landslide disasters in July 2018 in Southwestern Japan yet again exemplified the severity of slope failure-related damage and the need for improvement of early warning systems. The Japanese Meteorological Agency (JMA) uses a method based on a threshold value of soil water index (SWI), a conceptual measurement that represents saturation of slope soil. The current SWI early warning system uses 60-min rainfall data on a 5-km2 mesh and does not take into consideration other landslide conditioning factors such as slope angle and geology. This study calculates SWI values during the July 2018 disasters in Kure City (Hiroshima Prefecture) using 1-min XRAIN rainfall data in a 250-m mesh to investigate the relationship between SWI and landslide occurrence. It was found that the SWI threshold of 124 mm used in the JMA early warning system for the area was surpassed in all cells. A new SWI threshold calculation method taking slope angle and geology into consideration and produced with machine learning is proposed, comprising power lines for different geological units at a two-dimensional graph where points located above the threshold line represent landslide risk. It is judged that this method would provide a more accurate early warning system for landslide disasters.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"27 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82864758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-19DOI: 10.3390/geotechnics3030036
Jude Zeitouny, W. Lieske, Arash Alimardani Lavasan, Eva Heinz, M. Wichern, T. Wichtmann
Microbially induced calcite precipitation (MICP) is a green bio-inspired soil solidification technique that depends on the ability of urease-producing bacteria to form calcium carbonate that bonds soil grains and, consequently, improves soil mechanical properties. Meanwhile, different treatment methods have been adopted to tackle the key challenges in achieving effective MICP treatment. This paper proposes the combined method as a new MICP treatment approach, aiming to develop the efficiency of MICP treatment methods and simulate naturally cemented soil. This method combines the premixing, percolation, and submerging MICP methods. The strength outcomes of Portland-cemented and MICP-cemented sand using the percolation and combined methods were compared. For Portland-cemented sand, the UCS values varied from 0.6 MPa to 17.2 MPa, corresponding to cementation levels ranging from 5% to 30%. For MICP-cemented sand, the percolation method yielded UCS values ranging from 0.5 to 0.9 MPa, while the combined method achieved 3.7 MPa. The strength obtained by the combined method is around 3.7 times higher than that of the percolation method. The stiffness of bio-cemented samples varied between 20 and 470 MPa, while for Portland-cemented sand, it ranged from 130 to 1200 MPa. In terms of calcium carbonate distribution, the percolation method exhibited higher concentration at the top of the sample, while the combined method exhibited more precipitation at the top and perimeter, with less concentration in the central bottom region, equivalent to 10% of a half section’s area.
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