Pub Date : 2023-06-11DOI: 10.3390/geotechnics3020027
M. Ahmad, Richard Ray
Resonant column (RC) and the torsional simple shear (TOSS) tests have shown proven competency in acquiring precise and repeatable measurements regarding the shear modulus and damping ratio of soil. For most dynamic geotechnical problems, the shear modulus represents the stiffness of the soil, while the damping ratio describes energy dissipation. Many studies in the last few decades focused on developing the relevant equipment and investigating the effect of different soil properties on the dynamic behavior of soil. Researchers have introduced correlations to approximate this behavior without conducting dynamic torsional testing. Soil models (e.g., Ramberg-Osgood and Hardin-Drnevich) can simulate shear stress-strain curves after finding the curve-fitting parameters. Due to the complexity of dynamic behavior and its dependency on various factors in soils, the RO and HD equations help model the behavior more simply. This paper presents a literature review and evaluation of the studies, correlations, soil models, and parameters affecting the dynamic behavior of dry sand under torsion.
{"title":"The Dynamic Properties of Sand under Torsion: A Literature Review","authors":"M. Ahmad, Richard Ray","doi":"10.3390/geotechnics3020027","DOIUrl":"https://doi.org/10.3390/geotechnics3020027","url":null,"abstract":"Resonant column (RC) and the torsional simple shear (TOSS) tests have shown proven competency in acquiring precise and repeatable measurements regarding the shear modulus and damping ratio of soil. For most dynamic geotechnical problems, the shear modulus represents the stiffness of the soil, while the damping ratio describes energy dissipation. Many studies in the last few decades focused on developing the relevant equipment and investigating the effect of different soil properties on the dynamic behavior of soil. Researchers have introduced correlations to approximate this behavior without conducting dynamic torsional testing. Soil models (e.g., Ramberg-Osgood and Hardin-Drnevich) can simulate shear stress-strain curves after finding the curve-fitting parameters. Due to the complexity of dynamic behavior and its dependency on various factors in soils, the RO and HD equations help model the behavior more simply. This paper presents a literature review and evaluation of the studies, correlations, soil models, and parameters affecting the dynamic behavior of dry sand under torsion.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"14 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72735345","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 : 2023-06-11DOI: 10.3390/geotechnics3020028
S. Shafi, J. Takemura, V. Kunasegaram
Two centrifuge model tests were conducted, each with three large diameter steel tubular piles installed under similar conditions, i.e., diameter (Φ) = 2 m; thickness (t) = 25 mm; loading height from the rock surface (HL) = 6.5 m, but different rock socketing depths (dr), i.e., 2 m, 3 m, and 4 m, respectively, in prototype scale. Two additional 1 g model tests were conducted using the same model pile and ground. The results indicate that the pile lateral resistance increased with an increase in the rock socketing depth to diameter ratio (dr/Φ) in both 1 g and 50 g models. However, the difference between the two gravitational acceleration levels became visible in the non-linear behaviour as the imposed displacement increased. Specifically, the 1 g models showed larger residual displacement and less stiffness in reloading than the 50 g models, particularly under cyclic loading. Two types of ultimate failure modes were observed, i.e., rock failure and pile structural failure with local buckling just above the rock surface. The latter failure mode was only attained in the pile with a dr/Φ ratio of 2 in a 50 g models among the test conditions adopted in the models, but not in the 1 g model.
{"title":"Physical Modelling of High Stiffness Large Diameter Steel Tubular Pile Subjected to One-Way Horizontal Cyclic Loading","authors":"S. Shafi, J. Takemura, V. Kunasegaram","doi":"10.3390/geotechnics3020028","DOIUrl":"https://doi.org/10.3390/geotechnics3020028","url":null,"abstract":"Two centrifuge model tests were conducted, each with three large diameter steel tubular piles installed under similar conditions, i.e., diameter (Φ) = 2 m; thickness (t) = 25 mm; loading height from the rock surface (HL) = 6.5 m, but different rock socketing depths (dr), i.e., 2 m, 3 m, and 4 m, respectively, in prototype scale. Two additional 1 g model tests were conducted using the same model pile and ground. The results indicate that the pile lateral resistance increased with an increase in the rock socketing depth to diameter ratio (dr/Φ) in both 1 g and 50 g models. However, the difference between the two gravitational acceleration levels became visible in the non-linear behaviour as the imposed displacement increased. Specifically, the 1 g models showed larger residual displacement and less stiffness in reloading than the 50 g models, particularly under cyclic loading. Two types of ultimate failure modes were observed, i.e., rock failure and pile structural failure with local buckling just above the rock surface. The latter failure mode was only attained in the pile with a dr/Φ ratio of 2 in a 50 g models among the test conditions adopted in the models, but not in the 1 g model.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"15 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81925697","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 : 2023-06-07DOI: 10.3390/geotechnics3020026
A. Abdallah, G. Russo, O. Cuisinier
The mechanical efficiency of soil stabilization with cement is mainly controlled by various parameters, namely, the amount of binder, the compaction soil state and the curing conditions. The strength of the treated soil is the result of a complex combination of several factors that condition the physicochemical processes involved in cement hydration, which are difficult to monitor. The objective of this study is to identify the relevant parameters governing the bonding in cement-treated soil and suggest a predictive model for strength evolution using these parameters as input. To this purpose, an extensive testing program is presented to assess the impact of the initial water content (11–18%) and dry density (1.6–1.87 Mg/m3) as well as cement dosage (3 and 6%) in sealed curing conditions for 0, 7, 28 and 90 days. The water content variation, the total suction and the compressive strength were measured after different curing durations. The experimental results are first discussed in the parameters’ space, and then through a principal components analysis to overcome the complexity due to the parameters’ interdependency. The PCA revealed that the cement dosage explained 40% of the dataset variance, the remaining 60% being related to a combination of the initial state and curing time. Finally, a predictive model based on an artificial neural network was developed and tested. The predicted results were excellent, with an R2 of +0.99 with the training data and +0.93 with the testing data. These results should be improved by extending the dataset to include different soils and additional compaction conditions.
{"title":"Statistical and Predictive Analyses of the Strength Development of a Cement-Treated Clayey Soil","authors":"A. Abdallah, G. Russo, O. Cuisinier","doi":"10.3390/geotechnics3020026","DOIUrl":"https://doi.org/10.3390/geotechnics3020026","url":null,"abstract":"The mechanical efficiency of soil stabilization with cement is mainly controlled by various parameters, namely, the amount of binder, the compaction soil state and the curing conditions. The strength of the treated soil is the result of a complex combination of several factors that condition the physicochemical processes involved in cement hydration, which are difficult to monitor. The objective of this study is to identify the relevant parameters governing the bonding in cement-treated soil and suggest a predictive model for strength evolution using these parameters as input. To this purpose, an extensive testing program is presented to assess the impact of the initial water content (11–18%) and dry density (1.6–1.87 Mg/m3) as well as cement dosage (3 and 6%) in sealed curing conditions for 0, 7, 28 and 90 days. The water content variation, the total suction and the compressive strength were measured after different curing durations. The experimental results are first discussed in the parameters’ space, and then through a principal components analysis to overcome the complexity due to the parameters’ interdependency. The PCA revealed that the cement dosage explained 40% of the dataset variance, the remaining 60% being related to a combination of the initial state and curing time. Finally, a predictive model based on an artificial neural network was developed and tested. The predicted results were excellent, with an R2 of +0.99 with the training data and +0.93 with the testing data. These results should be improved by extending the dataset to include different soils and additional compaction conditions.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"45 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79960246","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}
This study investigated the role of pore fluid pH in governing the microstructural characteristics of loess soil and its ultimate effect on collapse mechanisms. A series of standard oedometer tests was conducted to evaluate the impact of acidic and alkaline pore fluid pH on the collapse behaviour of loess. The microstructural characterisation of soil exposed to different values of pore fluid pH was done by performing microscopic analysis of specimens before and after oedometer tests. In addition, the obtained micrographs were processed using an image analysis tool in order to interpret the influence of different pore fluid pH interactions on the evolution of soil pore-size distribution characteristics. The results obtained in this study indicated that the pore fluid pH has significant effect on the structural stability of loess and on the evolution of pore-size distribution during consolidation and consequently, on its wetting-induced collapse behaviour.
{"title":"Effect of pore fluid pH on the collapse behaviour and microstructural evolution of a loess","authors":"SiddiquaSumi, BigdeliAmin, CherianChinchu","doi":"10.1680/jenge.20.00011","DOIUrl":"https://doi.org/10.1680/jenge.20.00011","url":null,"abstract":"This study investigated the role of pore fluid pH in governing the microstructural characteristics of loess soil and its ultimate effect on collapse mechanisms. A series of standard oedometer tests was conducted to evaluate the impact of acidic and alkaline pore fluid pH on the collapse behaviour of loess. The microstructural characterisation of soil exposed to different values of pore fluid pH was done by performing microscopic analysis of specimens before and after oedometer tests. In addition, the obtained micrographs were processed using an image analysis tool in order to interpret the influence of different pore fluid pH interactions on the evolution of soil pore-size distribution characteristics. The results obtained in this study indicated that the pore fluid pH has significant effect on the structural stability of loess and on the evolution of pore-size distribution during consolidation and consequently, on its wetting-induced collapse behaviour.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136261481","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 : 2023-05-22DOI: 10.3390/geotechnics3020025
S. Haake, W. Krugh, E. Montoya, J. Guo
Wildfires can cause debris flow events in affected areas due to changes in the physical properties of burned soils, which are linked to burn severity. A study in California’s Sierra Nevada explored the impact of burn severity on soil physical properties using various tests. Results showed that higher burn-severity soils had higher total organic carbon content and liquid limit, and the plastic limit was also higher. The plasticity index was highest among low burn-severity soils, and high burn-severity soils had lower smectite and kaolinite/chlorite abundances compared to lower burn-severity soils. Grain size distribution and shear strength were not significantly impacted by burn severity. The study suggests that total organic carbon content is the most significant factor affecting the physical and mechanical properties of soil. These findings may help assess debris flow hazards in burned areas and highlight the need for further research on the effects of wildfires on soil properties and their contribution to debris flow events.
{"title":"Burn Severity and Its Impact on Soil Properties: A Study of the 2016 Erskine Fire in the Southern Sierra Nevada, California","authors":"S. Haake, W. Krugh, E. Montoya, J. Guo","doi":"10.3390/geotechnics3020025","DOIUrl":"https://doi.org/10.3390/geotechnics3020025","url":null,"abstract":"Wildfires can cause debris flow events in affected areas due to changes in the physical properties of burned soils, which are linked to burn severity. A study in California’s Sierra Nevada explored the impact of burn severity on soil physical properties using various tests. Results showed that higher burn-severity soils had higher total organic carbon content and liquid limit, and the plastic limit was also higher. The plasticity index was highest among low burn-severity soils, and high burn-severity soils had lower smectite and kaolinite/chlorite abundances compared to lower burn-severity soils. Grain size distribution and shear strength were not significantly impacted by burn severity. The study suggests that total organic carbon content is the most significant factor affecting the physical and mechanical properties of soil. These findings may help assess debris flow hazards in burned areas and highlight the need for further research on the effects of wildfires on soil properties and their contribution to debris flow events.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"39 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77696938","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 : 2023-05-21DOI: 10.3390/geotechnics3020024
A. Momeni, K. Eshiet, Y. Sheng
Sand is a particulate material but is treated as a continuum solid in some engineering analyses. This approach is proven to be acceptable when dealing with geotechnical structures, provided an adequate factor of safety is applied so that there is no risk of failure. However, the continuum approach does not account for the effect of interparticle forces on the micro–macro behaviour of sand. Sand could be modelled as a particulate material using the discrete element method (DEM), taking into account its discrete nature. This paper shows how the microscopic contact properties between the idealised sand particles influence the macro-mechanical behaviour, highlighting the development of the fabric as the soil approaches failure. Thirty DEM biaxial tests were performed to study the sensitivity of the macro–micro mechanical properties of sand to the inter-particle properties of an idealised sand particle. The conditions of these simulations were the same (e.g., particle size distribution, number of particles, porosity after radius enlargement, boundary conditions, and rate of loading). The sensitivity of the pre-peak, peak, and post-peak behaviour of these simulations to the inter-particle properties of an idealised sand particle was studied. Two extra DEM biaxial tests under different confining pressures were performed to verify the cohesionless nature of the synthetic material used for this study. Since a two-dimensional DEM is used for this study, a detailed approach to interpret the results assuming either a plane strain or a plane stress situation was discussed. This study highlighted the critical inter-particle properties and the range over which these influence macro-mechanical behaviour. The results show that Young’s modulus is mainly dependent on the normal contact stiffness, and peak stress and the angle of internal friction are greatly dependent on the inter-particle coefficient of friction, while Poisson’s ratio and volumetric behaviour of particulate sand are dictated mainly by shear contact stiffness. A set of relationships were established between inter-particle properties and macro-machinal parameters such as Young’s modulus, Poisson’s ratio, and angle of internal friction. The elastoplastic parameters obtained from these tests are qualitatively in agreement with the typical medium and dense sand behaviour.
{"title":"The Sensitivity of Micro—Macro Mechanical Behaviour of Sand to the Inter-Particle Properties","authors":"A. Momeni, K. Eshiet, Y. Sheng","doi":"10.3390/geotechnics3020024","DOIUrl":"https://doi.org/10.3390/geotechnics3020024","url":null,"abstract":"Sand is a particulate material but is treated as a continuum solid in some engineering analyses. This approach is proven to be acceptable when dealing with geotechnical structures, provided an adequate factor of safety is applied so that there is no risk of failure. However, the continuum approach does not account for the effect of interparticle forces on the micro–macro behaviour of sand. Sand could be modelled as a particulate material using the discrete element method (DEM), taking into account its discrete nature. This paper shows how the microscopic contact properties between the idealised sand particles influence the macro-mechanical behaviour, highlighting the development of the fabric as the soil approaches failure. Thirty DEM biaxial tests were performed to study the sensitivity of the macro–micro mechanical properties of sand to the inter-particle properties of an idealised sand particle. The conditions of these simulations were the same (e.g., particle size distribution, number of particles, porosity after radius enlargement, boundary conditions, and rate of loading). The sensitivity of the pre-peak, peak, and post-peak behaviour of these simulations to the inter-particle properties of an idealised sand particle was studied. Two extra DEM biaxial tests under different confining pressures were performed to verify the cohesionless nature of the synthetic material used for this study. Since a two-dimensional DEM is used for this study, a detailed approach to interpret the results assuming either a plane strain or a plane stress situation was discussed. This study highlighted the critical inter-particle properties and the range over which these influence macro-mechanical behaviour. The results show that Young’s modulus is mainly dependent on the normal contact stiffness, and peak stress and the angle of internal friction are greatly dependent on the inter-particle coefficient of friction, while Poisson’s ratio and volumetric behaviour of particulate sand are dictated mainly by shear contact stiffness. A set of relationships were established between inter-particle properties and macro-machinal parameters such as Young’s modulus, Poisson’s ratio, and angle of internal friction. The elastoplastic parameters obtained from these tests are qualitatively in agreement with the typical medium and dense sand behaviour.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"1 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84057984","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 : 2023-05-18DOI: 10.3390/geotechnics3020023
Vidit Singh, T. Uchimura
The geotechnical properties of municipal solid waste (MSW) are required to design and maintain a landfill structure. Several landfill failures occurring in recent times have led to the loss of revenue and people. This study aims to investigate the impact of material composition on the geotechnical properties of fresh synthetic municipal solid waste (SMSW), which imitates the real waste produced in India. The study aims to understand the contribution of each material, such as paper, plastic, and organic matter, on the shear behavior of SMSW, which is essential for designing landfills and ensuring their safety and performance. A modified proctor test and a large-scale direct shear test were used to determine the unit weight and shear strength of SMSW, respectively. The synthetic waste’s unit weight and shear strength were found to be consistent with values that had already been published. The shear strength parameters of SMSW include cohesion, which was determined to be at the lower bound of the envelope, and friction angle within the envelope. Lower unit weight, less fine soil-like material, and dry material are thought to be the causes of the observed variation in the behavior of actual waste in synthetic waste. The findings of this experiment demonstrated that as the proportion of paper increases, the cohesion (C) increases, and the friction angle (Φ) decreases. Cohesion and friction angle both decrease as the proportion of plastic increases. Cohesion and friction angle both increase with an increase in the organic percentage. These findings demonstrate that each material contributes differently to the shear behavior of SMSW. Hence, the material composition’s effect should be considered while designing a landfill for improved safety and reliability.
{"title":"Effect of Material Composition on Geotechnical Properties—Study on Synthetic Municipal Solid Waste","authors":"Vidit Singh, T. Uchimura","doi":"10.3390/geotechnics3020023","DOIUrl":"https://doi.org/10.3390/geotechnics3020023","url":null,"abstract":"The geotechnical properties of municipal solid waste (MSW) are required to design and maintain a landfill structure. Several landfill failures occurring in recent times have led to the loss of revenue and people. This study aims to investigate the impact of material composition on the geotechnical properties of fresh synthetic municipal solid waste (SMSW), which imitates the real waste produced in India. The study aims to understand the contribution of each material, such as paper, plastic, and organic matter, on the shear behavior of SMSW, which is essential for designing landfills and ensuring their safety and performance. A modified proctor test and a large-scale direct shear test were used to determine the unit weight and shear strength of SMSW, respectively. The synthetic waste’s unit weight and shear strength were found to be consistent with values that had already been published. The shear strength parameters of SMSW include cohesion, which was determined to be at the lower bound of the envelope, and friction angle within the envelope. Lower unit weight, less fine soil-like material, and dry material are thought to be the causes of the observed variation in the behavior of actual waste in synthetic waste. The findings of this experiment demonstrated that as the proportion of paper increases, the cohesion (C) increases, and the friction angle (Φ) decreases. Cohesion and friction angle both decrease as the proportion of plastic increases. Cohesion and friction angle both increase with an increase in the organic percentage. These findings demonstrate that each material contributes differently to the shear behavior of SMSW. Hence, the material composition’s effect should be considered while designing a landfill for improved safety and reliability.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"16 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82924992","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}
Xuan-chen Ding, Dingxin Zhang, Chenglong Wang, Gangqiang Kon, Haojie Lu
In recent years, energy piles have been widely used in the collection of shallow geothermal energy. However, the engineering characteristics of the soil and the mechanical behavior of the pile are affected by temperature, especially in clay. To explore the influence of heating-cooling cycles on the thermo-mechanical response of an energy pile in saturated clay, a laboratory model test was designed. The energy pile in saturated clay was subjected to ten heating-cooling cycles. A fiber Bragg grating (FBG) system was adopted to monitor the pile strain. Meanwhile, pile and soil temperature, pore water pressure, and pile top displacement data were collected by a dynamic acquisition instrument. The results show that FBG sensors can achieve good results in measuring the axial strain of the pile. The distribution and transmission of thermally induced axial force and stress are affected by soil properties and pile constraints. Temperature cycling will lead to the thermal consolidation of saturated clay, improving the bearing performance of energy piles, and to an irreversible settlement of the energy pile.
{"title":"Investigation on thermo-mechanical response of energy piles in saturated clay based on an FBG system","authors":"Xuan-chen Ding, Dingxin Zhang, Chenglong Wang, Gangqiang Kon, Haojie Lu","doi":"10.1680/jenge.22.00120","DOIUrl":"https://doi.org/10.1680/jenge.22.00120","url":null,"abstract":"In recent years, energy piles have been widely used in the collection of shallow geothermal energy. However, the engineering characteristics of the soil and the mechanical behavior of the pile are affected by temperature, especially in clay. To explore the influence of heating-cooling cycles on the thermo-mechanical response of an energy pile in saturated clay, a laboratory model test was designed. The energy pile in saturated clay was subjected to ten heating-cooling cycles. A fiber Bragg grating (FBG) system was adopted to monitor the pile strain. Meanwhile, pile and soil temperature, pore water pressure, and pile top displacement data were collected by a dynamic acquisition instrument. The results show that FBG sensors can achieve good results in measuring the axial strain of the pile. The distribution and transmission of thermally induced axial force and stress are affected by soil properties and pile constraints. Temperature cycling will lead to the thermal consolidation of saturated clay, improving the bearing performance of energy piles, and to an irreversible settlement of the energy pile.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42117528","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 : 2023-05-17DOI: 10.3390/geotechnics3020021
Kazi Moinul Islam, S. Gassman
The new Mechanistic-Empirical Pavement Design Guide (MEPDG) uses the subgrade resilient modulus (MR) as the key input parameter to represent the subgrade soil behavior for pavement design. The resilient modulus increases with an increase in confining pressure, whereas, for an increase in deviatoric stress, it increases for granular soils and decreases for fine-grained soils. The value of MR is highly stress dependent, with the stress state (i.e., bulk stress) a function of the position of the materials in the pavement structure and applied traffic loading. Applying excessive vertical stress at the top of the subgrade without knowing the appropriate stress state can result in permanent deformation. In situ stress must be calculated so the correct resilient modulus can be determined. To facilitate the implementation of MEPDG, this study develops a methodology to select the appropriate subgrade resilient modulus for predicting rutting and IRI. A comprehensive research methodology was undertaken to study the effect of in situ or undisturbed subgrade MR on pavement performance using the MEPDG. Results show that MR obtained from in situ stress is approximately 1.4 times higher than the MR estimate from NCHRP-285. Thus, the in situ stress significantly affects the calculation of subgrade MR and, subsequently, the use of MR in the predicted rutting, with IRI using the AASHTOWare pavement mechanistic-empirical design. Results also show that the pavement sections were classified as in “Good” and “Fair” conditions for rutting and IRI, respectively, considering in situ MR.
{"title":"Effect of the Field-Stress State on the Subgrade Resilient Modulus for Pavement Rutting and IRI","authors":"Kazi Moinul Islam, S. Gassman","doi":"10.3390/geotechnics3020021","DOIUrl":"https://doi.org/10.3390/geotechnics3020021","url":null,"abstract":"The new Mechanistic-Empirical Pavement Design Guide (MEPDG) uses the subgrade resilient modulus (MR) as the key input parameter to represent the subgrade soil behavior for pavement design. The resilient modulus increases with an increase in confining pressure, whereas, for an increase in deviatoric stress, it increases for granular soils and decreases for fine-grained soils. The value of MR is highly stress dependent, with the stress state (i.e., bulk stress) a function of the position of the materials in the pavement structure and applied traffic loading. Applying excessive vertical stress at the top of the subgrade without knowing the appropriate stress state can result in permanent deformation. In situ stress must be calculated so the correct resilient modulus can be determined. To facilitate the implementation of MEPDG, this study develops a methodology to select the appropriate subgrade resilient modulus for predicting rutting and IRI. A comprehensive research methodology was undertaken to study the effect of in situ or undisturbed subgrade MR on pavement performance using the MEPDG. Results show that MR obtained from in situ stress is approximately 1.4 times higher than the MR estimate from NCHRP-285. Thus, the in situ stress significantly affects the calculation of subgrade MR and, subsequently, the use of MR in the predicted rutting, with IRI using the AASHTOWare pavement mechanistic-empirical design. Results also show that the pavement sections were classified as in “Good” and “Fair” conditions for rutting and IRI, respectively, considering in situ MR.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"11 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87960088","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}
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