K. Wang, Wenjie Tan, Yanxiao Si, Yue Ma, Xiaohui Chen, A. Ding
Rock, soil and many porous-like materials are often fractured or structured media, which can exhibit dual-porosity behaviour. Studies on solute transport in deformable dual-porosity media remain challenging due to the multi-physics coupled effects and the complex interaction between fracture (or macropore) and porous matrix. Though several studies exist on constitutive modelling of coupled behaviour in deformable dual-porosity, the previously developed models are not systematic in thermodynamical frameworks. This paper proposes a Mixture Coupling Theory approach based on nonequilibrium thermodynamics to develop the solute transport model with consideration of hydro-mechanical coupling in dual-porosity media (referred to as the ST-HM model). This paper derives the constitutive equations of fully hydro-mechanical coupled behaviour in dual-porosity media and considers the pore and fracture porosity evolution influenced by both hydro and mechanical fields. Therefore, the governing equations of ST-HM are capable of predicting non-reactive solute transport with a fully hydro-mechanical coupled effect in dual-porosity media. Then, the model was verified against existing models and validated by relevant experimental results. Further, a numerical example shows that the presented model significantly improves the accuracy of the prediction of porosity, fluid pressure, and solute concentration compared with previous models, which ignore the fully hydro-mechanical coupled effects on solute transport.
{"title":"A Mixture Coupling Theory based model for solute transport in deformable dual-porosity media","authors":"K. Wang, Wenjie Tan, Yanxiao Si, Yue Ma, Xiaohui Chen, A. Ding","doi":"10.1680/jenge.22.00029","DOIUrl":"https://doi.org/10.1680/jenge.22.00029","url":null,"abstract":"Rock, soil and many porous-like materials are often fractured or structured media, which can exhibit dual-porosity behaviour. Studies on solute transport in deformable dual-porosity media remain challenging due to the multi-physics coupled effects and the complex interaction between fracture (or macropore) and porous matrix. Though several studies exist on constitutive modelling of coupled behaviour in deformable dual-porosity, the previously developed models are not systematic in thermodynamical frameworks. This paper proposes a Mixture Coupling Theory approach based on nonequilibrium thermodynamics to develop the solute transport model with consideration of hydro-mechanical coupling in dual-porosity media (referred to as the ST-HM model). This paper derives the constitutive equations of fully hydro-mechanical coupled behaviour in dual-porosity media and considers the pore and fracture porosity evolution influenced by both hydro and mechanical fields. Therefore, the governing equations of ST-HM are capable of predicting non-reactive solute transport with a fully hydro-mechanical coupled effect in dual-porosity media. Then, the model was verified against existing models and validated by relevant experimental results. Further, a numerical example shows that the presented model significantly improves the accuracy of the prediction of porosity, fluid pressure, and solute concentration compared with previous models, which ignore the fully hydro-mechanical coupled effects on solute transport.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43858921","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 : 2023-04-16DOI: 10.3390/geotechnics3020013
I. Akram, S. Azam
The geotechnical behavior of cohesionless soils is governed by field conditions. Such soils exist in two distinct forms, namely: disintegrated, such as fresh sediments under no overburden and/or no suction, and intact, such as old deposits with overburden and/or suction. The main contribution of this research was the successful capture of field conditions in laboratory samples, and the determination of shear strength under saturated and dried states. Results indicated that disintegrated samples possess identical soil behavior under both saturation states. Shear stiffness and peak shear increased with increasing normal stress, and no clear failure peaks were observed, similar to loose soils. Both samples showed an initial contraction followed by dilation at low normal stresses and mostly contraction at high normal stresses. Apparent cohesion was non-existent, and the friction angle measured 44.5° in the saturated state and 48° in the dried state. The intact sample exhibited behavior similar to the disintegrated sample when saturated. Under the dried state, clear failure peaks followed by residual shear were observed, similar to dense soils. Soil response was primarily dilative at low normal stresses and largely contractive under high normal stresses. Apparent cohesion was zero, and friction angle was 42° in the saturated state and changed to 91 kPa and 36°, respectively, in the dried state. Finally, structural cohesion increased with normal stress, and the friction angle due to suction was between 0.05° and 0.02°.
{"title":"Effect of Sample Preparation on Saturated and Unsaturated Shear Strength of Cohesionless Soils","authors":"I. Akram, S. Azam","doi":"10.3390/geotechnics3020013","DOIUrl":"https://doi.org/10.3390/geotechnics3020013","url":null,"abstract":"The geotechnical behavior of cohesionless soils is governed by field conditions. Such soils exist in two distinct forms, namely: disintegrated, such as fresh sediments under no overburden and/or no suction, and intact, such as old deposits with overburden and/or suction. The main contribution of this research was the successful capture of field conditions in laboratory samples, and the determination of shear strength under saturated and dried states. Results indicated that disintegrated samples possess identical soil behavior under both saturation states. Shear stiffness and peak shear increased with increasing normal stress, and no clear failure peaks were observed, similar to loose soils. Both samples showed an initial contraction followed by dilation at low normal stresses and mostly contraction at high normal stresses. Apparent cohesion was non-existent, and the friction angle measured 44.5° in the saturated state and 48° in the dried state. The intact sample exhibited behavior similar to the disintegrated sample when saturated. Under the dried state, clear failure peaks followed by residual shear were observed, similar to dense soils. Soil response was primarily dilative at low normal stresses and largely contractive under high normal stresses. Apparent cohesion was zero, and friction angle was 42° in the saturated state and changed to 91 kPa and 36°, respectively, in the dried state. Finally, structural cohesion increased with normal stress, and the friction angle due to suction was between 0.05° and 0.02°.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"1 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83381832","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 : 2023-04-13DOI: 10.3390/geotechnics3020012
H. Nowamooz
This work investigates the equilibrium stage of the crack propagation of a fine-grained soil after several drying and wetting cycles (shrinkage and swelling hysteresis). This stage is found to be crucial in practical engineering since the soil continues to show its irreversible hydraulic settlement, which is a potential risk for some severe structural damages. The shrinkage area and the shrinkage crack area were determined by using the image processing method. For the cyclic experimental investigations, the shrinkage cracks were followed during six months of successive wetting and drying cycles for two samples (with two different initial water contents). These long-term tests were completed by some short term single drying path tests performed on samples prepared at different initial states. The results showed the existence of a unique equilibrium stage at the end of the wetting and drying cycles for the two studied samples. The equilibrated soil subsidence was separated into two parts: the reversible settlement of the equilibrium stage and the irreversible settlements cumulated during successive wetting and drying cycles. At the equilibrium stage, the reversible deformation was 5.9% and the irreversible deformation was 3.8%. A simplified theoretical approach was also used to predict the cracking equilibrium stage and its soil subsidence. The fitted parameters of the theoretical approach for each cycle were stabilized to confirm the existence of this equilibrium stage.
{"title":"Equilibrium Stage of Soil Cracking and Subsidence after Several Wetting and Drying Cycles","authors":"H. Nowamooz","doi":"10.3390/geotechnics3020012","DOIUrl":"https://doi.org/10.3390/geotechnics3020012","url":null,"abstract":"This work investigates the equilibrium stage of the crack propagation of a fine-grained soil after several drying and wetting cycles (shrinkage and swelling hysteresis). This stage is found to be crucial in practical engineering since the soil continues to show its irreversible hydraulic settlement, which is a potential risk for some severe structural damages. The shrinkage area and the shrinkage crack area were determined by using the image processing method. For the cyclic experimental investigations, the shrinkage cracks were followed during six months of successive wetting and drying cycles for two samples (with two different initial water contents). These long-term tests were completed by some short term single drying path tests performed on samples prepared at different initial states. The results showed the existence of a unique equilibrium stage at the end of the wetting and drying cycles for the two studied samples. The equilibrated soil subsidence was separated into two parts: the reversible settlement of the equilibrium stage and the irreversible settlements cumulated during successive wetting and drying cycles. At the equilibrium stage, the reversible deformation was 5.9% and the irreversible deformation was 3.8%. A simplified theoretical approach was also used to predict the cracking equilibrium stage and its soil subsidence. The fitted parameters of the theoretical approach for each cycle were stabilized to confirm the existence of this equilibrium stage.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"118 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79395742","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}
The present study aims at perspective utilization of two wastes, bauxite residue (BR)-an extremely alkaline material and phosphogyspum (PG)-a highly acidic substance, of entirely different in nature. Development of alkali activated mortar targeting pavement applications has been explored. As BR and PG alone proved to be ineffectual in developing geopolymer/alkali activated mortar because of undesirably low compressive strength, the challenge lies in synthesis of alkali activated mortar envisioning high strength using the combination of these wastes. PG in proportions of 10, 20, 30, 40 and 50%, NaOH molarity of 8, 10, 12, and 14, and Na2SiO3/NaOH ratio of 0.5, 1.0, 1.5, 2.0 and 2.5 are chosen as variable parameters to develop the mortar. From the comprehensive experimental results, 30% of PG, 12 M NaOH and Na2SiO3/NaOH ratio of 1.5 are found as optimum parameters to synthesize the mortar. It is demonstrated that the mortar made at 70:30 combinations of BR and PG exhibits superior compressive strength of 31.24 MPa, minimum abrasion loss of 1.52 mm, and water absorption of <7%, apart from constraining leaching of potentially toxic elements. On account of mechanical, durability and environmental performance, the present study recommends the above combination as ideally suitable material in pavement applications.
{"title":"Synthesis of alkali activated mortar using phosphogypsum neutralized bauxite residue","authors":"","doi":"10.1680/jenge.22.00104","DOIUrl":"https://doi.org/10.1680/jenge.22.00104","url":null,"abstract":"The present study aims at perspective utilization of two wastes, bauxite residue (BR)-an extremely alkaline material and phosphogyspum (PG)-a highly acidic substance, of entirely different in nature. Development of alkali activated mortar targeting pavement applications has been explored. As BR and PG alone proved to be ineffectual in developing geopolymer/alkali activated mortar because of undesirably low compressive strength, the challenge lies in synthesis of alkali activated mortar envisioning high strength using the combination of these wastes. PG in proportions of 10, 20, 30, 40 and 50%, NaOH molarity of 8, 10, 12, and 14, and Na2SiO3/NaOH ratio of 0.5, 1.0, 1.5, 2.0 and 2.5 are chosen as variable parameters to develop the mortar. From the comprehensive experimental results, 30% of PG, 12 M NaOH and Na2SiO3/NaOH ratio of 1.5 are found as optimum parameters to synthesize the mortar. It is demonstrated that the mortar made at 70:30 combinations of BR and PG exhibits superior compressive strength of 31.24 MPa, minimum abrasion loss of 1.52 mm, and water absorption of <7%, apart from constraining leaching of potentially toxic elements. On account of mechanical, durability and environmental performance, the present study recommends the above combination as ideally suitable material in pavement applications.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"1 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41325910","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 : 2023-04-11DOI: 10.3390/geotechnics3020011
N. Bandara, H. Hettiarachchi, E. Jensen, T. Binoy, R. Perera
Remove-and-replace with suitable material has been the primary solution used for improving subgrades in Michigan, USA, when weak subgrades are encountered in road construction. Considering the large extent of silty and clayey soils found in southeastern Michigan, where much of the population and the roads are located within the state, the earthwork associated with this solution is massive and expensive. The use of cement kiln dust (CKD) or lime kiln dust (LKD) as a subgrade stabilizer can be a cost-effective solution if there is sufficient evidence to prove that such stabilization is suitable for the soils and the climate in southeastern Michigan. This became the subject of a field and laboratory investigation carried out in Michigan and sponsored by the Michigan Department of Transportation. The findings from the laboratory portion of this research (which were published in a separate manuscript) proved CKD’s suitability for long-term stabilization and LKD’s capacity for being a stabilizer for short-term modifications of clayey soils found in southeastern Michigan. This study covers the field testing portion of this investigation. Two CKD-stabilized and another two LKD-stabilized subgrades, which were already in use for 4–6 years, were tested for strength, using dynamic cone penetration (DCP) tests. The California bearing ratios estimated from the DCP tests showed that the CKD-stabilized and LKD-stabilized subgrades could offer strength gains as high as 200–515% and 149–257% compared to in situ soils, respectively, even after 4–6 years in use.
{"title":"Using Kiln Dust to Improve Weak Subgrades for Pavement Construction: A Field Verification in Michigan, USA","authors":"N. Bandara, H. Hettiarachchi, E. Jensen, T. Binoy, R. Perera","doi":"10.3390/geotechnics3020011","DOIUrl":"https://doi.org/10.3390/geotechnics3020011","url":null,"abstract":"Remove-and-replace with suitable material has been the primary solution used for improving subgrades in Michigan, USA, when weak subgrades are encountered in road construction. Considering the large extent of silty and clayey soils found in southeastern Michigan, where much of the population and the roads are located within the state, the earthwork associated with this solution is massive and expensive. The use of cement kiln dust (CKD) or lime kiln dust (LKD) as a subgrade stabilizer can be a cost-effective solution if there is sufficient evidence to prove that such stabilization is suitable for the soils and the climate in southeastern Michigan. This became the subject of a field and laboratory investigation carried out in Michigan and sponsored by the Michigan Department of Transportation. The findings from the laboratory portion of this research (which were published in a separate manuscript) proved CKD’s suitability for long-term stabilization and LKD’s capacity for being a stabilizer for short-term modifications of clayey soils found in southeastern Michigan. This study covers the field testing portion of this investigation. Two CKD-stabilized and another two LKD-stabilized subgrades, which were already in use for 4–6 years, were tested for strength, using dynamic cone penetration (DCP) tests. The California bearing ratios estimated from the DCP tests showed that the CKD-stabilized and LKD-stabilized subgrades could offer strength gains as high as 200–515% and 149–257% compared to in situ soils, respectively, even after 4–6 years in use.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"99 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79298070","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 : 2023-04-06DOI: 10.3390/geotechnics3020010
Mani Axel, Xi‐An Li, Feng Wen, Ming-Xiao An
In this study, cement was used as a component to provide a stabilizing effect in order to evaluate the hardness and stability of loess soil. To evaluate the strength properties of loess soil reinforced with cement, samples with four distinct cement concentrations (3%, 5%, 7%, and 9%) and three distinct curing durations (7, 14, and 28 days) were generated. During a series of tests, the flexural strength, direct shear strength, indirect tensile strength, and unconfined compressive strength were determined. An appropriate cement dosage was found, in addition to a durability index that could be used to quantify the effect of water absorption investigations on cement-stabilized loess. Both of these discoveries were made simultaneously. Scanning electron microscopy (SEM) and energy dispersive X-ray fluorescence spectrometry (XRF) examinations were carried out so that the fundamental mechanics of the materials could be comprehended. The results show that the cohesion of cement-stabilized loess is much more sensitive to structure than the friction angle of the material. The increase in shear strength after remoulding is due to cohesion. The SEM study showed that the cement interacted with the loess particles to produce a thick cement network that successfully covered the voids and boosted the mixture’s strength parameters. The 28-days UCS for the samples containing 7% cement was the greatest, at 3.5 MPa, while the UCS for those containing 9% cement was 4.78 MPa. The highest flexural tensile strength of 1.98 N/mm2 was determined after 28 days. The tensile strength after 7 days in samples containing 3%, 5%, 7%, and 9% cement reached a maximum force of 0.15 MPa, 0.23 MPa, 0.27 MPa, and 0.37 MPa, respectively, and increased with each passing day. To achieve the desired level of strength, it is necessary to adjust the proportion of cement. In addition, as the curing period progressed, we observed an increase in the resistance and stiffness of the cement-stabilized loess due to the interactions that take place between the structure and the mineral composition. It is believed that this event was caused by naturally occurring cementation. As a consequence of this reaction, the production of new cementitious materials takes place. The cation exchange that causes the hydration and pozzolanic reaction that leads to the creation of aggregates and interparticle flocculation is responsible for their production. These findings suggest that cement may be utilised as a simple and effective method of loess stabilization, ultimately resulting in improved performance of the loess. Therefore, this study revealed that cement may considerably enhance the microstructure and strength parameters of loess. This research provides important information on cement-stabilized loess that has ramifications for geotechnical investigation, construction, research, and testing to achieve a successful project.
{"title":"Microstructure and Strength Parameters of Cement-Stabilized Loess","authors":"Mani Axel, Xi‐An Li, Feng Wen, Ming-Xiao An","doi":"10.3390/geotechnics3020010","DOIUrl":"https://doi.org/10.3390/geotechnics3020010","url":null,"abstract":"In this study, cement was used as a component to provide a stabilizing effect in order to evaluate the hardness and stability of loess soil. To evaluate the strength properties of loess soil reinforced with cement, samples with four distinct cement concentrations (3%, 5%, 7%, and 9%) and three distinct curing durations (7, 14, and 28 days) were generated. During a series of tests, the flexural strength, direct shear strength, indirect tensile strength, and unconfined compressive strength were determined. An appropriate cement dosage was found, in addition to a durability index that could be used to quantify the effect of water absorption investigations on cement-stabilized loess. Both of these discoveries were made simultaneously. Scanning electron microscopy (SEM) and energy dispersive X-ray fluorescence spectrometry (XRF) examinations were carried out so that the fundamental mechanics of the materials could be comprehended. The results show that the cohesion of cement-stabilized loess is much more sensitive to structure than the friction angle of the material. The increase in shear strength after remoulding is due to cohesion. The SEM study showed that the cement interacted with the loess particles to produce a thick cement network that successfully covered the voids and boosted the mixture’s strength parameters. The 28-days UCS for the samples containing 7% cement was the greatest, at 3.5 MPa, while the UCS for those containing 9% cement was 4.78 MPa. The highest flexural tensile strength of 1.98 N/mm2 was determined after 28 days. The tensile strength after 7 days in samples containing 3%, 5%, 7%, and 9% cement reached a maximum force of 0.15 MPa, 0.23 MPa, 0.27 MPa, and 0.37 MPa, respectively, and increased with each passing day. To achieve the desired level of strength, it is necessary to adjust the proportion of cement. In addition, as the curing period progressed, we observed an increase in the resistance and stiffness of the cement-stabilized loess due to the interactions that take place between the structure and the mineral composition. It is believed that this event was caused by naturally occurring cementation. As a consequence of this reaction, the production of new cementitious materials takes place. The cation exchange that causes the hydration and pozzolanic reaction that leads to the creation of aggregates and interparticle flocculation is responsible for their production. These findings suggest that cement may be utilised as a simple and effective method of loess stabilization, ultimately resulting in improved performance of the loess. Therefore, this study revealed that cement may considerably enhance the microstructure and strength parameters of loess. This research provides important information on cement-stabilized loess that has ramifications for geotechnical investigation, construction, research, and testing to achieve a successful project.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"16 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79703346","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 work examines the study of engineering properties and leachate characteristics of ground granulated blast furnace slag (GGBS) blended with laterite soil-bentonite mixtures as a bottom landfill liner. In this study, laterite soil is referred to as non-expansive and non-plastic clay; on the contrary bentonite is highly expansive and high plastic clay. Laboratory experiments were performed to quantify the effect of GGBS-laterite soil-bentonite mixtures on the liquid limit (LL), free swell index (FSI), compaction characteristics, unconfined compressive strength (UCS), hydraulic conductivity (k), and leachate tests. As GGBS percentage in the mix blend increases, the LL, FSI, optimum moisture content, k determined with deionized water/diesel oil contaminants and leachate concentration decreases, whereas maximum dry densities and UCS value increases. Furthermore, X-ray diffraction analysis and energy dispersive X-ray spectrometer was performed on UCS samples to determine the evidence of hydration reaction in mix blends at 0, 14, and 28 days curing period. The test results revealed that an increase in Ca: Si ratio and a decrease in Al: Ca ratios, augmented the UCS enhancement during the curing period. Consequently, 20% GGBS combined with laterite soil-bentonite mixes proves to be the ideal material for landfill bottom liners in waste containment systems.
{"title":"Assessment of engineering properties on GGBS mixtures as a bottom liner in landfills","authors":"Manikanta Devarangadi, U. M","doi":"10.1680/jenge.22.00166","DOIUrl":"https://doi.org/10.1680/jenge.22.00166","url":null,"abstract":"This work examines the study of engineering properties and leachate characteristics of ground granulated blast furnace slag (GGBS) blended with laterite soil-bentonite mixtures as a bottom landfill liner. In this study, laterite soil is referred to as non-expansive and non-plastic clay; on the contrary bentonite is highly expansive and high plastic clay. Laboratory experiments were performed to quantify the effect of GGBS-laterite soil-bentonite mixtures on the liquid limit (LL), free swell index (FSI), compaction characteristics, unconfined compressive strength (UCS), hydraulic conductivity (k), and leachate tests. As GGBS percentage in the mix blend increases, the LL, FSI, optimum moisture content, k determined with deionized water/diesel oil contaminants and leachate concentration decreases, whereas maximum dry densities and UCS value increases. Furthermore, X-ray diffraction analysis and energy dispersive X-ray spectrometer was performed on UCS samples to determine the evidence of hydration reaction in mix blends at 0, 14, and 28 days curing period. The test results revealed that an increase in Ca: Si ratio and a decrease in Al: Ca ratios, augmented the UCS enhancement during the curing period. Consequently, 20% GGBS combined with laterite soil-bentonite mixes proves to be the ideal material for landfill bottom liners in waste containment systems.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44452900","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}
The usage of various polymers as an alternative in ground improvement problems is steadily gaining popularity. However, certain aspects of the usage of polymers are still not properly addressed. In this paper, an experimental program has been undertaken to study the influence of various polymer contents on the shear wave velocities in granular soils. Different polymer concentrations are mixed with a uniform sand to obtain various concentrations. Resonant column tests are carried out under three different mean effective stresses considering various densities. The results suggest a significant influence of polymer under low stress values due to the coating that reduces normal contact forces between sand grains. The influence of the coating is further seen to decrease since under higher stresses- the coatings are significantly damaged, leading to increase in the stiffness of the specimens the values of which are closer to that measured for the pure sand.
{"title":"The influence of polymer content on the shear wave velocities in fine sand","authors":"D. Sarkar, W. Lieske, M. Goudarzy, T. Wichtmann","doi":"10.1680/jenge.23.00017","DOIUrl":"https://doi.org/10.1680/jenge.23.00017","url":null,"abstract":"The usage of various polymers as an alternative in ground improvement problems is steadily gaining popularity. However, certain aspects of the usage of polymers are still not properly addressed. In this paper, an experimental program has been undertaken to study the influence of various polymer contents on the shear wave velocities in granular soils. Different polymer concentrations are mixed with a uniform sand to obtain various concentrations. Resonant column tests are carried out under three different mean effective stresses considering various densities. The results suggest a significant influence of polymer under low stress values due to the coating that reduces normal contact forces between sand grains. The influence of the coating is further seen to decrease since under higher stresses- the coatings are significantly damaged, leading to increase in the stiffness of the specimens the values of which are closer to that measured for the pure sand.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43526040","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}
The effect of low temperature and degree of saturation has important influences on the surrounding rock mechanical properties of cave-type Liquefied natural gas underground storage. Uniaxial compression tests were carried out on dry and saturated granite under different real-time loading at designated low temperatures (25, 0, −20, −40, −50 and −60 °C) conditions. The porosity and microstructure were then observed by nuclear magnetic resonance and scanning electron microscopy. The results show that with the decrease of temperature, the uniaxial compressive strength (UCS) and porosity of both the dry and saturated granite monotonously increases, while the elastic modulus undergoes increase-decrease transition, and finally stabilizes. At the same temperature, the UCS and elastic modulus of the dry granite are generally greater than those of the saturated granite. The reinforcement in the UCS and elastic modulus is caused by cold shrinkage, while the degradation in the elastic modulus, especially for the saturated granite, is attributed to freezing damage below 0°C. The results of this study can provide technical support for the long-term stability analysis and evaluation of underground cavernous Liquefied natural gas storage reservoirs.
{"title":"Experimental study on uniaxial compression of granite under real-time loading at designated low temperatures conditions","authors":"Yi-feng Zhang, Fan Zhang, Dun-Bo Lv, X. Ding","doi":"10.1680/jenge.22.00031","DOIUrl":"https://doi.org/10.1680/jenge.22.00031","url":null,"abstract":"The effect of low temperature and degree of saturation has important influences on the surrounding rock mechanical properties of cave-type Liquefied natural gas underground storage. Uniaxial compression tests were carried out on dry and saturated granite under different real-time loading at designated low temperatures (25, 0, −20, −40, −50 and −60 °C) conditions. The porosity and microstructure were then observed by nuclear magnetic resonance and scanning electron microscopy. The results show that with the decrease of temperature, the uniaxial compressive strength (UCS) and porosity of both the dry and saturated granite monotonously increases, while the elastic modulus undergoes increase-decrease transition, and finally stabilizes. At the same temperature, the UCS and elastic modulus of the dry granite are generally greater than those of the saturated granite. The reinforcement in the UCS and elastic modulus is caused by cold shrinkage, while the degradation in the elastic modulus, especially for the saturated granite, is attributed to freezing damage below 0°C. The results of this study can provide technical support for the long-term stability analysis and evaluation of underground cavernous Liquefied natural gas storage reservoirs.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43918045","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 aims to estimate the effects of xanthan gum biopolymer on the wetting and drying processes of soils. Xanthan gum was used to treat jumunjin sand and sand/clay mixture with different content to the mass of dried soil. The wetting and drying soilwater characteristics of xanthan gum biopolymer-treated sand were investigated using capillary rise open tubes and Fredlund-type SWCC device, respectively. The results show that xanthan gum has a significant effect on controlling the movement of water in the soil. Xanthan gum biopolymer shapes the drying soil-water characteristic of the soils and forms the nonlinear relationship between xanthan gum content and soil-water characteristic parameters of the treated soils. Xanthan gum significantly reduces the capillary conductivity of soil down to 10−7 ∼ 10−8 m/s as the soil treated with 1.0% xanthan gum. Xanthan gum affects the capillary equilibrium process of water differently in wetting tests as well. Furthermore, the wetting results show the role of clay particles in the flow controlling performance of xanthan gum.
{"title":"Water retention properties of xanthan gum biopolymer-treated soils","authors":"I. Chang, G. Cho, Thi Tuong An Tran","doi":"10.1680/jenge.22.00098","DOIUrl":"https://doi.org/10.1680/jenge.22.00098","url":null,"abstract":"This study aims to estimate the effects of xanthan gum biopolymer on the wetting and drying processes of soils. Xanthan gum was used to treat jumunjin sand and sand/clay mixture with different content to the mass of dried soil. The wetting and drying soilwater characteristics of xanthan gum biopolymer-treated sand were investigated using capillary rise open tubes and Fredlund-type SWCC device, respectively. The results show that xanthan gum has a significant effect on controlling the movement of water in the soil. Xanthan gum biopolymer shapes the drying soil-water characteristic of the soils and forms the nonlinear relationship between xanthan gum content and soil-water characteristic parameters of the treated soils. Xanthan gum significantly reduces the capillary conductivity of soil down to 10−7 ∼ 10−8 m/s as the soil treated with 1.0% xanthan gum. Xanthan gum affects the capillary equilibrium process of water differently in wetting tests as well. Furthermore, the wetting results show the role of clay particles in the flow controlling performance of xanthan gum.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44081217","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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