Pub Date : 2023-05-17DOI: 10.3390/geotechnics3020022
Behzad Dastjerdy, A. Saeidi, Shahriyar Heidarzadeh
The reliability of geomechanical models and engineering designs depend heavily on high-quality data. In geomechanical projects, collecting and analyzing laboratory data is crucial in characterizing the mechanical properties of soils and rocks. However, insufficient lab data or underestimating data treatment can lead to unreliable data being used in the design stage, causing safety hazards, delays, or failures. Hence, detecting outliers or extreme values is significant for ensuring accurate geomechanical analysis. This study reviews and categorizes applicable outlier detection methods for geomechanical data into fence labeling methods and statistical tests. Using real geomechanical data, the applicability of these methods was examined based on four elements: data distribution, sensitivity to extreme values, sample size, and data skewness. The results indicated that statistical tests were less effective than fence labeling methods in detecting outliers in geomechanical data due to limitations in handling skewed data and small sample sizes. Thus, the best outlier detection method should consider this matter. Fence labeling methods, specifically, the medcouple boxplot and semi-interquartile range rule, were identified as the most accurate outlier detection methods for geomechanical data but may necessitate more advanced statistical techniques. Moreover, Tukey’s boxplot was found unsuitable for geomechanical data due to negative confidence intervals that conflicted with geomechanical principles.
{"title":"Review of Applicable Outlier Detection Methods to Treat Geomechanical Data","authors":"Behzad Dastjerdy, A. Saeidi, Shahriyar Heidarzadeh","doi":"10.3390/geotechnics3020022","DOIUrl":"https://doi.org/10.3390/geotechnics3020022","url":null,"abstract":"The reliability of geomechanical models and engineering designs depend heavily on high-quality data. In geomechanical projects, collecting and analyzing laboratory data is crucial in characterizing the mechanical properties of soils and rocks. However, insufficient lab data or underestimating data treatment can lead to unreliable data being used in the design stage, causing safety hazards, delays, or failures. Hence, detecting outliers or extreme values is significant for ensuring accurate geomechanical analysis. This study reviews and categorizes applicable outlier detection methods for geomechanical data into fence labeling methods and statistical tests. Using real geomechanical data, the applicability of these methods was examined based on four elements: data distribution, sensitivity to extreme values, sample size, and data skewness. The results indicated that statistical tests were less effective than fence labeling methods in detecting outliers in geomechanical data due to limitations in handling skewed data and small sample sizes. Thus, the best outlier detection method should consider this matter. Fence labeling methods, specifically, the medcouple boxplot and semi-interquartile range rule, were identified as the most accurate outlier detection methods for geomechanical data but may necessitate more advanced statistical techniques. Moreover, Tukey’s boxplot was found unsuitable for geomechanical data due to negative confidence intervals that conflicted with geomechanical principles.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"29 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82038347","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 : 2023-05-15DOI: 10.3390/geotechnics3020020
Diwakar KC, Liangbo Hu
Wildfires have a strong influence on various geotechnical and hydraulic properties of soils and sediments, which may become more vulnerable to landslides or debris flows. In the present study, a case investigation of the 2018 post-wildfire debris flows in Montecito, California, USA, was conducted, with a focus on the wildfire-affected areas and debris volume estimation. Significant debris were deposited around four major creeks, i.e., Montecito Creek, San Ysidro Creek, Buena Vista Creek, and Romero Creek in January, 2018, one month after the Thomas fire. Satellite images utilizing remote sensing techniques and geographic information system (GIS) data were analyzed to identify areas affected by the wildfire. Relevant data, including the slope, catchment area, and rainfall were used in two empirical models to estimate the debris volumes around the four creeks. As compared with field observation, each debris volume estimated with these empirical models was within the same order of magnitude. The debris volumes were generally underestimated when using the rainfall recorded at the Montecito Weather Station; the estimates considerably improved with the rainfall record from the Doulton Tunnel Station. The results showed that, overall, such empirical approaches are still of benefit for engineering practice, as they are capable of offering first-order approximations. The accuracy and availability of rainfall data are critical factors; the rainfall data in mountainous areas are generally higher than in the low lands, and consequently were more suitable for debris volume estimation in the present study, where the debris flows typically occurred in areas with steep slopes and at higher elevations.
{"title":"Post-Wildfire Debris Flows in Montecito, California (USA): A Case Study and Empirically Based Debris Volume Estimation","authors":"Diwakar KC, Liangbo Hu","doi":"10.3390/geotechnics3020020","DOIUrl":"https://doi.org/10.3390/geotechnics3020020","url":null,"abstract":"Wildfires have a strong influence on various geotechnical and hydraulic properties of soils and sediments, which may become more vulnerable to landslides or debris flows. In the present study, a case investigation of the 2018 post-wildfire debris flows in Montecito, California, USA, was conducted, with a focus on the wildfire-affected areas and debris volume estimation. Significant debris were deposited around four major creeks, i.e., Montecito Creek, San Ysidro Creek, Buena Vista Creek, and Romero Creek in January, 2018, one month after the Thomas fire. Satellite images utilizing remote sensing techniques and geographic information system (GIS) data were analyzed to identify areas affected by the wildfire. Relevant data, including the slope, catchment area, and rainfall were used in two empirical models to estimate the debris volumes around the four creeks. As compared with field observation, each debris volume estimated with these empirical models was within the same order of magnitude. The debris volumes were generally underestimated when using the rainfall recorded at the Montecito Weather Station; the estimates considerably improved with the rainfall record from the Doulton Tunnel Station. The results showed that, overall, such empirical approaches are still of benefit for engineering practice, as they are capable of offering first-order approximations. The accuracy and availability of rainfall data are critical factors; the rainfall data in mountainous areas are generally higher than in the low lands, and consequently were more suitable for debris volume estimation in the present study, where the debris flows typically occurred in areas with steep slopes and at higher elevations.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"79 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81341453","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}
In the present research, a comprehensive experimental investigation was carried out for the geotechnical characterisation of new synthetic lightweight aggregates (SLAs) composed of reused biomass fly ash and waste plastics (i.e. high-density and low-density polyethylene, i.e. HDPE and LDPE). Aggregate fly ash-to-plastic ratio, by weight, was 50:50. Both aggregates were characterised by low specific gravity values, i.e. 0.98. The physical, chemical and mechanical properties (i.e. one-dimensional compressibility, creep properties, compaction features and stress-strain-strength behavior) of lightweight aggregates were evaluated together with hydraulic conductivity and water absorbability. Based on one-dimensional compression test results, lightweight aggregates made of fly ash and HDPE resulted to be less compressible upon loading compared to the companion material made of fly ash and LDPE and exhibited an overall response similar to that of traditional aggregates of expanded clay. Moreover, the analysis of the time-dependent compressive behavior of the two synthetic lightweight aggregates showed that the creep rate depends on applied stress in the range of 50 kPa to 400 kPa with values of creep coefficients C αε slightly higher than those of compacted sand, but comparable, or even lower, than those of other recycled materials. Shear strength parameters, including peak friction angle (ϕ′) and cohesion intercept (c′), determined by isotropically consolidated drained triaxial compression tests, were very satisfactory for both aggregates. The ϕ′ is within the range of 42.3 to 46.3°, and c′ is in the range of 1.3 to 8.6 kPa, with the highest values concerning the fly ash-HDPE aggregate. Constant head permeability tests provided values of the hydraulic conductivity (k)in the range 3÷4·10−4 m/s evidencing favourable permeability properties of both investigated synthetic aggregates. Leaching tests and thermal stability analyses proved the sustainability of both aggregates from an environmental point of view. Finally, the results obtained in the present study demonstrate the suitability of the investigated lightweight synthetic aggregates for valuable use in many geotechnical applications.
{"title":"Environmental and geotechnical properties of lightweight aggregates made of reused solid wastes","authors":"D. Porcino, G. Tomasello, F. Mauriello, A. Malara","doi":"10.1680/jenge.22.00077","DOIUrl":"https://doi.org/10.1680/jenge.22.00077","url":null,"abstract":"In the present research, a comprehensive experimental investigation was carried out for the geotechnical characterisation of new synthetic lightweight aggregates (SLAs) composed of reused biomass fly ash and waste plastics (i.e. high-density and low-density polyethylene, i.e. HDPE and LDPE). Aggregate fly ash-to-plastic ratio, by weight, was 50:50. Both aggregates were characterised by low specific gravity values, i.e. 0.98. The physical, chemical and mechanical properties (i.e. one-dimensional compressibility, creep properties, compaction features and stress-strain-strength behavior) of lightweight aggregates were evaluated together with hydraulic conductivity and water absorbability. Based on one-dimensional compression test results, lightweight aggregates made of fly ash and HDPE resulted to be less compressible upon loading compared to the companion material made of fly ash and LDPE and exhibited an overall response similar to that of traditional aggregates of expanded clay. Moreover, the analysis of the time-dependent compressive behavior of the two synthetic lightweight aggregates showed that the creep rate depends on applied stress in the range of 50 kPa to 400 kPa with values of creep coefficients C αε slightly higher than those of compacted sand, but comparable, or even lower, than those of other recycled materials. Shear strength parameters, including peak friction angle (ϕ′) and cohesion intercept (c′), determined by isotropically consolidated drained triaxial compression tests, were very satisfactory for both aggregates. The ϕ′ is within the range of 42.3 to 46.3°, and c′ is in the range of 1.3 to 8.6 kPa, with the highest values concerning the fly ash-HDPE aggregate. Constant head permeability tests provided values of the hydraulic conductivity (k)in the range 3÷4·10−4 m/s evidencing favourable permeability properties of both investigated synthetic aggregates. Leaching tests and thermal stability analyses proved the sustainability of both aggregates from an environmental point of view. Finally, the results obtained in the present study demonstrate the suitability of the investigated lightweight synthetic aggregates for valuable use in many geotechnical applications.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46255687","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 : 2023-05-06DOI: 10.3390/geotechnics3020019
Yu Wang, Rolando P Orense
Inclined piles have been widely applied as one of the countermeasures against large lateral spreading induced by soil liquefaction during earthquakes. However, the unsatisfactory performance of inclined piles in past events has impeded their application in seismic areas. To elucidate the performance of inclined piles when subjected to lateral spreading induced by soil liquefaction, numerical analyzes were performed using the OpenSees framework. For this purpose, a comprehensive three-dimensional finite element model was developed. Interface elements were used between the soil and the pile to account for the friction and gapping mechanisms. A multi-yield-surface plasticity constitutive relationship for sand was adopted to simulate the soil liquefaction behavior. Based on the proposed numerical model, parametric analyzes were conducted to investigate the influence of various factors on the behavior of inclined piles, including the raked angle of the pile, the ground slope, the soil profile, and the amplitude of the input motion. The response of the system indicates that inclined piles can behave better than vertical piles in decreasing soil deformation and the cap response. The influences of the investigated factors are highlighted to adopt the appropriate pile inclination in laterally spreading ground and maximize the advantages of using inclined piles.
{"title":"Numerical Investigation of Inclined Piles under Liquefaction-Induced Lateral Spreading","authors":"Yu Wang, Rolando P Orense","doi":"10.3390/geotechnics3020019","DOIUrl":"https://doi.org/10.3390/geotechnics3020019","url":null,"abstract":"Inclined piles have been widely applied as one of the countermeasures against large lateral spreading induced by soil liquefaction during earthquakes. However, the unsatisfactory performance of inclined piles in past events has impeded their application in seismic areas. To elucidate the performance of inclined piles when subjected to lateral spreading induced by soil liquefaction, numerical analyzes were performed using the OpenSees framework. For this purpose, a comprehensive three-dimensional finite element model was developed. Interface elements were used between the soil and the pile to account for the friction and gapping mechanisms. A multi-yield-surface plasticity constitutive relationship for sand was adopted to simulate the soil liquefaction behavior. Based on the proposed numerical model, parametric analyzes were conducted to investigate the influence of various factors on the behavior of inclined piles, including the raked angle of the pile, the ground slope, the soil profile, and the amplitude of the input motion. The response of the system indicates that inclined piles can behave better than vertical piles in decreasing soil deformation and the cap response. The influences of the investigated factors are highlighted to adopt the appropriate pile inclination in laterally spreading ground and maximize the advantages of using inclined piles.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"214 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75758155","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 : 2023-05-05DOI: 10.3390/geotechnics3020017
A. Yerro, F. Ceccato
Interactions between soil, fluids (e.g., water), and structures are intrinsic to most geotechnical problems. However, these can be extremely complex and further understanding is needed in this field. Soil–water–structure interactions can be studied on many different scales (micro to macro) and perspectives (experimental, numerical, and theoretical). In any case, the consequences of these interactions control soil behaviour, the stability of civil infrastructure, and, ultimately, the safety of our communities. This Special Issue consists of five papers (three research papers and two literature reviews) that highlight the importance of soil–water–structure interactions in a broad range of different applications. The topics addressed in the research contributions include (a) the performance of shallow footings under oblique loads, (b) the assessment of nonlinear base-isolated building systems under dynamic loading, and (c) the applicability of lightweight materials as fill for retaining wall systems. The other innovative papers, on the other hand, provide comprehensive reviews on (d) the role of the clay content in the interface characteristics between sand–clay mixtures and structures and (e) the latest developments in the understanding and measurements of the Atterberg limits.
{"title":"Soil–Water–Structure Interactions","authors":"A. Yerro, F. Ceccato","doi":"10.3390/geotechnics3020017","DOIUrl":"https://doi.org/10.3390/geotechnics3020017","url":null,"abstract":"Interactions between soil, fluids (e.g., water), and structures are intrinsic to most geotechnical problems. However, these can be extremely complex and further understanding is needed in this field. Soil–water–structure interactions can be studied on many different scales (micro to macro) and perspectives (experimental, numerical, and theoretical). In any case, the consequences of these interactions control soil behaviour, the stability of civil infrastructure, and, ultimately, the safety of our communities. This Special Issue consists of five papers (three research papers and two literature reviews) that highlight the importance of soil–water–structure interactions in a broad range of different applications. The topics addressed in the research contributions include (a) the performance of shallow footings under oblique loads, (b) the assessment of nonlinear base-isolated building systems under dynamic loading, and (c) the applicability of lightweight materials as fill for retaining wall systems. The other innovative papers, on the other hand, provide comprehensive reviews on (d) the role of the clay content in the interface characteristics between sand–clay mixtures and structures and (e) the latest developments in the understanding and measurements of the Atterberg limits.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"33 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91329040","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 : 2023-05-05DOI: 10.3390/geotechnics3020018
Chun-Hsing Ho, Jeremy DeGeyter, Dada Zhang
This paper provides a five-year performance evaluation of an application of geogrid reinforcement in low-volume unpaved roads using dynamic cone penetrometer (DCP), plate load tests (PLT), and roadway sensing method. A Forest Service unpaved road located in northern Arizona, USA, exhibited severe deterioration on the surface, creating an unsafe traffic environment for vehicles. A total of four structural sections (1–4; 4.3 m wide) were installed in the 40 m long test area. One additional section of existing subgrade/roadbed with native soil adjacent to the test sections was used for comparison purposes. The project was originally completed in November 2015, followed by five annual field visits to observe surface conditions of the five test sections. Based on DCP and PLT results (both conducted in 2015), and roadway sensing tests conducted in 2020, the section made of 30 cm thick aggregate with one geogrid layer appeared to have a better capacity for resisting traffic loading as compared with the other four sections. This paper concludes that, from a long-term point of view, the geogrid reinforcement improves the capacity of the unpaved roads, with significantly reduced rutting and damage from both roadway traffic loads and weathering effects.
{"title":"Five-Year Performance Evaluation of Geogrid Reinforcement in Low-Volume Unpaved Roads Using Dynamic Cone Penetrometer, Plate Load Test and Roadway Sensing","authors":"Chun-Hsing Ho, Jeremy DeGeyter, Dada Zhang","doi":"10.3390/geotechnics3020018","DOIUrl":"https://doi.org/10.3390/geotechnics3020018","url":null,"abstract":"This paper provides a five-year performance evaluation of an application of geogrid reinforcement in low-volume unpaved roads using dynamic cone penetrometer (DCP), plate load tests (PLT), and roadway sensing method. A Forest Service unpaved road located in northern Arizona, USA, exhibited severe deterioration on the surface, creating an unsafe traffic environment for vehicles. A total of four structural sections (1–4; 4.3 m wide) were installed in the 40 m long test area. One additional section of existing subgrade/roadbed with native soil adjacent to the test sections was used for comparison purposes. The project was originally completed in November 2015, followed by five annual field visits to observe surface conditions of the five test sections. Based on DCP and PLT results (both conducted in 2015), and roadway sensing tests conducted in 2020, the section made of 30 cm thick aggregate with one geogrid layer appeared to have a better capacity for resisting traffic loading as compared with the other four sections. This paper concludes that, from a long-term point of view, the geogrid reinforcement improves the capacity of the unpaved roads, with significantly reduced rutting and damage from both roadway traffic loads and weathering effects.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"136 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79629692","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}
FengYongchang, ChenLin, MereySukru, LijithKoorthedath Pullayikodi, SinghDevendra N, KomiyaAtsuki, MaruyamaShigenao
Gas hydrates are regarded as one of the most promising alternative sources of energy, which have the potential to address the energy demand of a contemporary society. Based on the field explorations in the Eastern Nankai Trough (Japan), a multilayered hydrate reservoir model has been conceptualised and its behaviours during depressurisation production are simulated. This model incorporates the effects of the initial reservoir temperature and permeability on the mechanism of hydrate dissociation, which in turn affects the gas production. It is shown that the dissociation process is largely affected by the initial temperature distribution within the reservoir layers, and the ‘warmer’ reservoirs show (consistently) higher production potential. Furthermore, the gas production could be improved significantly, by increasing the permeability of the wellbore region, which can be achieved through the fracturing process. The close match between the simulation results and the field tests is noteworthy. The proposed multilayered model would be quite useful for analysing the efficacy of the ‘production strategy’, in most real-life situations.
{"title":"Simulation of gas production from hydrate reservoirs (AT1) of Eastern Nankai Trough, Japan","authors":"FengYongchang, ChenLin, MereySukru, LijithKoorthedath Pullayikodi, SinghDevendra N, KomiyaAtsuki, MaruyamaShigenao","doi":"10.1680/jenge.19.00177","DOIUrl":"https://doi.org/10.1680/jenge.19.00177","url":null,"abstract":"Gas hydrates are regarded as one of the most promising alternative sources of energy, which have the potential to address the energy demand of a contemporary society. Based on the field explorations in the Eastern Nankai Trough (Japan), a multilayered hydrate reservoir model has been conceptualised and its behaviours during depressurisation production are simulated. This model incorporates the effects of the initial reservoir temperature and permeability on the mechanism of hydrate dissociation, which in turn affects the gas production. It is shown that the dissociation process is largely affected by the initial temperature distribution within the reservoir layers, and the ‘warmer’ reservoirs show (consistently) higher production potential. Furthermore, the gas production could be improved significantly, by increasing the permeability of the wellbore region, which can be achieved through the fracturing process. The close match between the simulation results and the field tests is noteworthy. The proposed multilayered model would be quite useful for analysing the efficacy of the ‘production strategy’, in most real-life situations.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135399702","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 : 2023-04-30DOI: 10.3390/geotechnics3020016
Ashley P. Dyson, Ali Tolooiyan, D. V. Griffiths
It is well recognised that plant vegetation and roots are capable of improving the shear strength of hillslopes by reinforcing soil shear resistance. Several key factors influencing the level of slope reinforcement include root geometry, orientation and strength. To assess the mechanical performance of vegetated slopes using numerical methods, root structures can be represented by beam and pile elements to mirror root behaviour. In contrast, root reinforcement can be modelled indirectly through a root cohesion factor, supplying additional strength to the soil surrounding the root zone. In this paper, correlations between these two numerical methods are presented, highlighting the applicability of each technique based on various root characteristics. Three types of root geometries are presented, consisting of a primary tap root, a secondary cohesion zone surrounding the main root and a root branching process. The results of the finite element analysis demonstrate the variation in the slope factor of safety for both methods, with a set of correlations between the two modelling approaches. A series of stability charts are presented for each method, quantifying the effects of root characteristics on slope reinforcement.
{"title":"Numerical Modelling Techniques for Stability Analysis of Slopes Reinforced with Shallow Roots","authors":"Ashley P. Dyson, Ali Tolooiyan, D. V. Griffiths","doi":"10.3390/geotechnics3020016","DOIUrl":"https://doi.org/10.3390/geotechnics3020016","url":null,"abstract":"It is well recognised that plant vegetation and roots are capable of improving the shear strength of hillslopes by reinforcing soil shear resistance. Several key factors influencing the level of slope reinforcement include root geometry, orientation and strength. To assess the mechanical performance of vegetated slopes using numerical methods, root structures can be represented by beam and pile elements to mirror root behaviour. In contrast, root reinforcement can be modelled indirectly through a root cohesion factor, supplying additional strength to the soil surrounding the root zone. In this paper, correlations between these two numerical methods are presented, highlighting the applicability of each technique based on various root characteristics. Three types of root geometries are presented, consisting of a primary tap root, a secondary cohesion zone surrounding the main root and a root branching process. The results of the finite element analysis demonstrate the variation in the slope factor of safety for both methods, with a set of correlations between the two modelling approaches. A series of stability charts are presented for each method, quantifying the effects of root characteristics on slope reinforcement.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135564011","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 : 2023-04-28DOI: 10.3390/geotechnics3020015
Lila Mouali, G. Veylon, D. Dias, L. Peyras, C. Carvajal, J. Duriez, Eric Antoinet
This paper presents a laboratory investigation of the strain-dependent cyclic properties of a compacted tropical residual soil as measured in a resonant column and cyclic triaxial testing program. The mechanical properties were evaluated with respect to cyclic shear strain amplitude, initial void ratio, and confining pressure. It was shown that the existing models for the prediction of shear modulus reduction and damping ratio curves were not pertinent in the case of the compacted residual soil studied. Empirical equations were developed for the small-strain shear modulus and the normalized shear modulus, damping ratio, and pore water pressure ratio curves for void ratios between e = 1.00 and e = 1.50 and mean effective pressures of p′ = 50−300 kPa. The comparison of the models to the measured values suggest that the uncertainties associated with each of these models are lower than 20% of the predicted values. The results were established as part of a project for the construction of an embankment dam in the West Indies. However, the methodology as well as the model formulation framework presented in the article can be generalized to other residual soils and applied in all fields of geotechnical engineering.
{"title":"Dynamic Properties of a Compacted Residual Soil from the West Indies","authors":"Lila Mouali, G. Veylon, D. Dias, L. Peyras, C. Carvajal, J. Duriez, Eric Antoinet","doi":"10.3390/geotechnics3020015","DOIUrl":"https://doi.org/10.3390/geotechnics3020015","url":null,"abstract":"This paper presents a laboratory investigation of the strain-dependent cyclic properties of a compacted tropical residual soil as measured in a resonant column and cyclic triaxial testing program. The mechanical properties were evaluated with respect to cyclic shear strain amplitude, initial void ratio, and confining pressure. It was shown that the existing models for the prediction of shear modulus reduction and damping ratio curves were not pertinent in the case of the compacted residual soil studied. Empirical equations were developed for the small-strain shear modulus and the normalized shear modulus, damping ratio, and pore water pressure ratio curves for void ratios between e = 1.00 and e = 1.50 and mean effective pressures of p′ = 50−300 kPa. The comparison of the models to the measured values suggest that the uncertainties associated with each of these models are lower than 20% of the predicted values. The results were established as part of a project for the construction of an embankment dam in the West Indies. However, the methodology as well as the model formulation framework presented in the article can be generalized to other residual soils and applied in all fields of geotechnical engineering.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"25 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78170417","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 : 2023-04-23DOI: 10.3390/geotechnics3020014
L. M. Hernandez, E. Garzón, P. Sánchez-Soto, E. Morales
This research focuses on the potential for microbial treatment to stabilize compacted soils, which are often utilized in earthwork projects. A silt–clay sand was used to describe a particular kind of soil. The suggested remedy makes use of the soil’s naturally occurring urea and Ca2+, as well as microorganisms introduced to the compaction water. Two alternative initial water-content types were examined: those on the dry side and those close to the ideal Proctor conditions. Bacillaceae microorganisms were used to induce microbial CaCO3 precipitation and improve the hydraulic and mechanical properties of the compacted soil. The samples were biotreated and immediately compacted, so that the precipitation of calcium carbonate during the curing process took place in the contact areas between the particles (biocementation) and in the pore space (bioclogging). A set of techniques were used to study the ageing effects, such as the water-retention curve by dew-points psychrometer, mercury porosimetry intrusion, permeability, ultrasonic pulse velocity, resonant column, and unconfined and tensile-compression tests. During the ageing, it was observed that the bacterial activity consumed water for the hydrolysis of urea and other intermediate reactions to precipitate CaCO3. This process resulted in a retraction of the microstructure and a change in the macrostructure. The bioclogging phenomenon was more evident in the soil microstructure, while the biocementation process was easier to observe in the macrostructure. The suction’s effects on the soil stiffness were studied in detail, and a significant increase was detected. Despite these water-content losses, which caused soil stiffening by increasing the suction, it was still feasible to identify the gradual rise in small-strain stiffness throughout incubation. The unconfined and tensile-compression tests showed a similar progressive increase in terms of peak compressive and peak splitting strength during the incubation. These results are of interest when microbiological treatments are applied in soils to produce cementitious materials, with the present investigation demonstrating a complete study of their geotechnical behaviour.
{"title":"Simultaneous Biocementation and Compaction of a Soil to Avoid the Breakage of Cementitious Structures during the Execution of Earthwork Constructions","authors":"L. M. Hernandez, E. Garzón, P. Sánchez-Soto, E. Morales","doi":"10.3390/geotechnics3020014","DOIUrl":"https://doi.org/10.3390/geotechnics3020014","url":null,"abstract":"This research focuses on the potential for microbial treatment to stabilize compacted soils, which are often utilized in earthwork projects. A silt–clay sand was used to describe a particular kind of soil. The suggested remedy makes use of the soil’s naturally occurring urea and Ca2+, as well as microorganisms introduced to the compaction water. Two alternative initial water-content types were examined: those on the dry side and those close to the ideal Proctor conditions. Bacillaceae microorganisms were used to induce microbial CaCO3 precipitation and improve the hydraulic and mechanical properties of the compacted soil. The samples were biotreated and immediately compacted, so that the precipitation of calcium carbonate during the curing process took place in the contact areas between the particles (biocementation) and in the pore space (bioclogging). A set of techniques were used to study the ageing effects, such as the water-retention curve by dew-points psychrometer, mercury porosimetry intrusion, permeability, ultrasonic pulse velocity, resonant column, and unconfined and tensile-compression tests. During the ageing, it was observed that the bacterial activity consumed water for the hydrolysis of urea and other intermediate reactions to precipitate CaCO3. This process resulted in a retraction of the microstructure and a change in the macrostructure. The bioclogging phenomenon was more evident in the soil microstructure, while the biocementation process was easier to observe in the macrostructure. The suction’s effects on the soil stiffness were studied in detail, and a significant increase was detected. Despite these water-content losses, which caused soil stiffening by increasing the suction, it was still feasible to identify the gradual rise in small-strain stiffness throughout incubation. The unconfined and tensile-compression tests showed a similar progressive increase in terms of peak compressive and peak splitting strength during the incubation. These results are of interest when microbiological treatments are applied in soils to produce cementitious materials, with the present investigation demonstrating a complete study of their geotechnical behaviour.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"35 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90566406","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：