Pub Date : 2021-09-23DOI: 10.1080/17486025.2021.1980231
Sreyashrao Surapreddi, P. Ghosh
ABSTRACT The attenuation response from a series of block vibration tests performed on a model square machine foundation at a site near IIT Kanpur, India, is reported in this paper. The dynamic response at different locations from the vibration source is measured for a wide range of frequencies. The observed attenuation response is compared with the analytical and the finite element (FE) solutions to bolster the experimental findings. A parametric study is conducted utilising the FE analysis to predict the surface wave mitigation characteristics in various soils. It can be observed that the surface waves dominate the attenuation characteristics at the far-field locations and attenuate at a faster rate in soft soils compared to stiff soils. The material and the geometric damping characteristics of the surface waves influence the attenuation characteristics of horizontal and vertical vibrations at the far-field pick-up points. The attenuation characteristics of horizontal and vertical amplitude responses are found to differ significantly. Curve fitting and regression analyses are also performed to develop simplified design expressions to predict the attenuation response of horizontal and vertical vibrations. The proposed design expressions compare well with the values reported in the literature and can be utilised by practicing engineers.
{"title":"Experimental and numerical investigations on attenuation response of machine foundations under vertical excitation","authors":"Sreyashrao Surapreddi, P. Ghosh","doi":"10.1080/17486025.2021.1980231","DOIUrl":"https://doi.org/10.1080/17486025.2021.1980231","url":null,"abstract":"ABSTRACT The attenuation response from a series of block vibration tests performed on a model square machine foundation at a site near IIT Kanpur, India, is reported in this paper. The dynamic response at different locations from the vibration source is measured for a wide range of frequencies. The observed attenuation response is compared with the analytical and the finite element (FE) solutions to bolster the experimental findings. A parametric study is conducted utilising the FE analysis to predict the surface wave mitigation characteristics in various soils. It can be observed that the surface waves dominate the attenuation characteristics at the far-field locations and attenuate at a faster rate in soft soils compared to stiff soils. The material and the geometric damping characteristics of the surface waves influence the attenuation characteristics of horizontal and vertical vibrations at the far-field pick-up points. The attenuation characteristics of horizontal and vertical amplitude responses are found to differ significantly. Curve fitting and regression analyses are also performed to develop simplified design expressions to predict the attenuation response of horizontal and vertical vibrations. The proposed design expressions compare well with the values reported in the literature and can be utilised by practicing engineers.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"17 1","pages":"1865 - 1886"},"PeriodicalIF":1.3,"publicationDate":"2021-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47554698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-23DOI: 10.1080/17486025.2021.1975049
Alireza Najma, J. Sharma
ABSTRACT This paper describes an analytical approach to investigating the role of failure mechanism in the bearing capacity of a smooth strip footing located on a - - soil. The approach combines the plane strain equilibrium condition and Mohr-Coulomb failure criterion to obtain the stress distribution along a translational, rotational and composite failure path. It is shown that the exact solutions for cohesion factor and surcharge factor for a - - soil do not require the superposition assumption and that both these factors are path-independent. A general closed-form path-dependent expression for the soil weight factor is also derived in terms of internal friction angle of the soil and the geometry of the failure path. The application of proposed expression on two-line and three-line failure modes as well as the well-known Hill mechanism are evaluated and discussed. Due to the overestimation of the soil weight factor by two-line and three-line modes, and by Hill mechanism, geometric modifications on the failure paths are proposed. The proposed mechanism and its bearing capacity are verified using the method of the stress characteristics. The effect of a non-associated flow rule on the reduction of the soil weight factor is also investigated quantitatively.
{"title":"Analytical evaluation of the effect of failure mechanisms on the bearing capacity factor Nγ for smooth strip footings","authors":"Alireza Najma, J. Sharma","doi":"10.1080/17486025.2021.1975049","DOIUrl":"https://doi.org/10.1080/17486025.2021.1975049","url":null,"abstract":"ABSTRACT This paper describes an analytical approach to investigating the role of failure mechanism in the bearing capacity of a smooth strip footing located on a - - soil. The approach combines the plane strain equilibrium condition and Mohr-Coulomb failure criterion to obtain the stress distribution along a translational, rotational and composite failure path. It is shown that the exact solutions for cohesion factor and surcharge factor for a - - soil do not require the superposition assumption and that both these factors are path-independent. A general closed-form path-dependent expression for the soil weight factor is also derived in terms of internal friction angle of the soil and the geometry of the failure path. The application of proposed expression on two-line and three-line failure modes as well as the well-known Hill mechanism are evaluated and discussed. Due to the overestimation of the soil weight factor by two-line and three-line modes, and by Hill mechanism, geometric modifications on the failure paths are proposed. The proposed mechanism and its bearing capacity are verified using the method of the stress characteristics. The effect of a non-associated flow rule on the reduction of the soil weight factor is also investigated quantitatively.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"17 1","pages":"1828 - 1851"},"PeriodicalIF":1.3,"publicationDate":"2021-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43948425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-21DOI: 10.1080/17486025.2021.1975044
Nosrati Seyed Alireza, A. Negahdar, H. Negahdar, E. Badakhshan
ABSATRACT Magnesium oxysulfate cements are modern green air-hardening magnesia-based cementitious materials that were produced using the chemical reaction of magnesium sulphate (MgSO4), magnesium oxide (MgO), distilled water and a small number of additive materials. In this paper, the influences of thawing and freezing cycles on the chemical-mechanical and microstructural properties of stabilised sulphate-rich clay with MOSC using a triaxial cell set-up, scanning electron microscopy and X-ray diffraction were investigated. The sulphate-rich clay specimens with various dosages of Magnesium Oxysulfate Cement (MOSC) and different curing times were exposed to one, two and three thawing and freezing cycles in soaked and un-soaked conditions. The consequences showed that the compression strength and behaviour of the stress and strain samples significantly depend on the amount of MOSC. The durability index which was described as the ratio of the resistance before and after stabilising revealed that the durability augments by the increase of MOSC. In addition, increasing curing times in the MOSC stabilised specimens leads to an increase in their compression resistance.
{"title":"Stabilised sulfate-rich clay with magnesium oxysulfate cement","authors":"Nosrati Seyed Alireza, A. Negahdar, H. Negahdar, E. Badakhshan","doi":"10.1080/17486025.2021.1975044","DOIUrl":"https://doi.org/10.1080/17486025.2021.1975044","url":null,"abstract":"ABSATRACT Magnesium oxysulfate cements are modern green air-hardening magnesia-based cementitious materials that were produced using the chemical reaction of magnesium sulphate (MgSO4), magnesium oxide (MgO), distilled water and a small number of additive materials. In this paper, the influences of thawing and freezing cycles on the chemical-mechanical and microstructural properties of stabilised sulphate-rich clay with MOSC using a triaxial cell set-up, scanning electron microscopy and X-ray diffraction were investigated. The sulphate-rich clay specimens with various dosages of Magnesium Oxysulfate Cement (MOSC) and different curing times were exposed to one, two and three thawing and freezing cycles in soaked and un-soaked conditions. The consequences showed that the compression strength and behaviour of the stress and strain samples significantly depend on the amount of MOSC. The durability index which was described as the ratio of the resistance before and after stabilising revealed that the durability augments by the increase of MOSC. In addition, increasing curing times in the MOSC stabilised specimens leads to an increase in their compression resistance.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"17 1","pages":"1751 - 1761"},"PeriodicalIF":1.3,"publicationDate":"2021-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49317031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-15DOI: 10.1080/17486025.2021.1975047
M. Karkush, Mahmoud S. Abdulkareem, H. Dekhn
ABSTRACT The effect of lime piles on the behavior of piled-raft foundation constructed on such soil and subjected to static and cyclic vertical loading was also investigated. The soil samples were contaminated artificially by light fuel oil (LFO) mixed with water and kerosene to simulate the contaminants that are usually disposed directly to the soil from the electricity power plant as a byproduct. The lime columns are holes of 20 mm diameter and 500 mm deep were drilled in the soil and filled with lime mixture. The lime mixture was prepared by mixing a dry soil with 15% of lime and natural water content and then poured into the holes and mixed thoroughly. The lime mixture was left for four weeks to allow the completion of most chemical reactions necessary for improvement and remediation of oil contaminated soil. Aluminum piles of 20 mm in diameter and 300 mm long were installed in soil models and subjected to static and cyclic vertical loading. Load-settlement curves showed that the contaminated soils have more settlement values compared with the intact soil, but improvement and remediation of soil samples showless settlement than that of contaminated samples. Lime piles are considered an efficient technique for decreasing the settlement of piled-raft foundations.
{"title":"Effect of Deep Remediation and Improvement on Bearing Capacity and Settlement of Piled Raft Foundation Subjected to Static and Cyclic Vertical Loading","authors":"M. Karkush, Mahmoud S. Abdulkareem, H. Dekhn","doi":"10.1080/17486025.2021.1975047","DOIUrl":"https://doi.org/10.1080/17486025.2021.1975047","url":null,"abstract":"ABSTRACT The effect of lime piles on the behavior of piled-raft foundation constructed on such soil and subjected to static and cyclic vertical loading was also investigated. The soil samples were contaminated artificially by light fuel oil (LFO) mixed with water and kerosene to simulate the contaminants that are usually disposed directly to the soil from the electricity power plant as a byproduct. The lime columns are holes of 20 mm diameter and 500 mm deep were drilled in the soil and filled with lime mixture. The lime mixture was prepared by mixing a dry soil with 15% of lime and natural water content and then poured into the holes and mixed thoroughly. The lime mixture was left for four weeks to allow the completion of most chemical reactions necessary for improvement and remediation of oil contaminated soil. Aluminum piles of 20 mm in diameter and 300 mm long were installed in soil models and subjected to static and cyclic vertical loading. Load-settlement curves showed that the contaminated soils have more settlement values compared with the intact soil, but improvement and remediation of soil samples showless settlement than that of contaminated samples. Lime piles are considered an efficient technique for decreasing the settlement of piled-raft foundations.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"17 1","pages":"1801 - 1811"},"PeriodicalIF":1.3,"publicationDate":"2021-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46731477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-15DOI: 10.1080/17486025.2021.1975048
A. Hossain, T. Alam, S. Barua, M. Rahman
ABSTRACT This study represents the angle of internal friction ( ) estimation of silty sand (SM) of Bangladesh using SPT-N, the depth of sample collection, and the grain size analysis results using machine learning models. To develop the predictive model, Multiple Linear Regression (MLR), Support Vector Regression (SVR) and Artificial Neural Network (ANN) algorithms are used. Soil samples have been collected from 210 boreholes beside the rail track of the Joydevpur-Mymensingh-Jamalpur section. The performance of the models is evaluated using the R2 score, Root Mean Squared Error (RMSE) and Mean Squared Error (MAE). According to the evaluation metrics, SVR with Radial Basis Function (Rbf) kernel performs better than ANN and MLR, and a web application is prepared providing estimated ϕ based on the user input. Later SVR is compared with the established empirical equations and shows that Wolff’s model is under-predicting and Nitish Puri’s model is over-predicting than actual ϕ. However, the model proposed in this study produces lower residual internal friction angle and improved R2 score, RMSE and MAE which can be used to predict the internal friction angle of silty sand in Bangladesh with higher precision.
{"title":"Estimation of shear strength parameter of silty sand from SPT-N60 using machine learning models","authors":"A. Hossain, T. Alam, S. Barua, M. Rahman","doi":"10.1080/17486025.2021.1975048","DOIUrl":"https://doi.org/10.1080/17486025.2021.1975048","url":null,"abstract":"ABSTRACT This study represents the angle of internal friction ( ) estimation of silty sand (SM) of Bangladesh using SPT-N, the depth of sample collection, and the grain size analysis results using machine learning models. To develop the predictive model, Multiple Linear Regression (MLR), Support Vector Regression (SVR) and Artificial Neural Network (ANN) algorithms are used. Soil samples have been collected from 210 boreholes beside the rail track of the Joydevpur-Mymensingh-Jamalpur section. The performance of the models is evaluated using the R2 score, Root Mean Squared Error (RMSE) and Mean Squared Error (MAE). According to the evaluation metrics, SVR with Radial Basis Function (Rbf) kernel performs better than ANN and MLR, and a web application is prepared providing estimated ϕ based on the user input. Later SVR is compared with the established empirical equations and shows that Wolff’s model is under-predicting and Nitish Puri’s model is over-predicting than actual ϕ. However, the model proposed in this study produces lower residual internal friction angle and improved R2 score, RMSE and MAE which can be used to predict the internal friction angle of silty sand in Bangladesh with higher precision.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"17 1","pages":"1812 - 1827"},"PeriodicalIF":1.3,"publicationDate":"2021-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46117582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-13DOI: 10.1080/17486025.2021.1975046
Shivanshi, A. Jha, Vijay Singh, Ankush Jain, M. Akhtar
ABSTRACT Lime treatment of soil is a widely adopted technique to improve its properties. However, the durability of lime-treated soil under varying environmental conditions such as contamination with chemical agents is still a matter of concern. An attempt has been made to examine the swelling behaviour of untreated and lime-treated expansive soil subjected to sulphate contamination (i.e. soluble gypsum). Series of the free swell index and one-dimensional oedometer swell tests have been performed in untreated and lime-treated soil inundating with soluble gypsum of varying sulphate concentration (i.e. low to high; 0 to 30000 ppm). The results of one-dimensional oedometer swell tests revealed that the sulphate contamination leads to the reduction in the maximum swelling percentage of untreated soil. On contrary, a drastic increase in the swelling percentage has been observed in the lime-treated soil subjected to contamination up to 16000 ppm, which diminishes thereafter with an increase in sulphate concentration. It is revealed that the sulphate contamination has observed promising effect on untreated soil; whereas a susceptible behaviour is pronounced in the lime-treated soil up to 16000 ppm sulphate concentration. Further, experimental outcomes are elucidated based on the detailed microanalyses (XRD, SEM, EDAX and FTIR) of samples.
{"title":"Effect of soluble gypsum on swell behaviour of lime-treated expansive soil – a micro-level investigation","authors":"Shivanshi, A. Jha, Vijay Singh, Ankush Jain, M. Akhtar","doi":"10.1080/17486025.2021.1975046","DOIUrl":"https://doi.org/10.1080/17486025.2021.1975046","url":null,"abstract":"ABSTRACT Lime treatment of soil is a widely adopted technique to improve its properties. However, the durability of lime-treated soil under varying environmental conditions such as contamination with chemical agents is still a matter of concern. An attempt has been made to examine the swelling behaviour of untreated and lime-treated expansive soil subjected to sulphate contamination (i.e. soluble gypsum). Series of the free swell index and one-dimensional oedometer swell tests have been performed in untreated and lime-treated soil inundating with soluble gypsum of varying sulphate concentration (i.e. low to high; 0 to 30000 ppm). The results of one-dimensional oedometer swell tests revealed that the sulphate contamination leads to the reduction in the maximum swelling percentage of untreated soil. On contrary, a drastic increase in the swelling percentage has been observed in the lime-treated soil subjected to contamination up to 16000 ppm, which diminishes thereafter with an increase in sulphate concentration. It is revealed that the sulphate contamination has observed promising effect on untreated soil; whereas a susceptible behaviour is pronounced in the lime-treated soil up to 16000 ppm sulphate concentration. Further, experimental outcomes are elucidated based on the detailed microanalyses (XRD, SEM, EDAX and FTIR) of samples.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"17 1","pages":"1786 - 1800"},"PeriodicalIF":1.3,"publicationDate":"2021-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42069813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-13DOI: 10.1080/17486025.2021.1975045
M. Hussain, A. Sachan
ABSTRACT Liquefaction and settlement of sandy soils cause significant damage during earthquakes. In this research, cohesionless soils of Kutch region with history of large earthquakes are explored. Twenty-six soil samples were collected from different locations of Kutch region and tested under saturated and moist conditions by performing two series of Electromechanical Dynamic Cyclic Simple Shear (EMDCSS) tests. In series I, the liquefaction characteristics of saturated samples were observed to be dependent on fines content and plasticity index. Kutch soils with non-plastic fines exhibited low liquefaction resistance and showed increased resistance at higher FC; however, for sands with plastic fines, PI rather than FC controlled the cyclic degradation. Saturated sandy soils with non-plastic fines exhibited lower shear stress mobilisation, higher pore pressure and larger degradation as compared to sands with clay content. In series II, the settlement characteristics of moist samples at constant normal stress revealed decreased axial deformation and increased mobilised shear stress with increased FC and PI. Silty-sands exhibited higher deformations and larger strength as compared to clayey-sands. The EMDCSS tests at saturated and moist conditions revealed Kutch soils to be prone to liquefaction and large settlements, respectively.
{"title":"Cyclic simple shear behaviour of saturated and moist sandy soils","authors":"M. Hussain, A. Sachan","doi":"10.1080/17486025.2021.1975045","DOIUrl":"https://doi.org/10.1080/17486025.2021.1975045","url":null,"abstract":"ABSTRACT Liquefaction and settlement of sandy soils cause significant damage during earthquakes. In this research, cohesionless soils of Kutch region with history of large earthquakes are explored. Twenty-six soil samples were collected from different locations of Kutch region and tested under saturated and moist conditions by performing two series of Electromechanical Dynamic Cyclic Simple Shear (EMDCSS) tests. In series I, the liquefaction characteristics of saturated samples were observed to be dependent on fines content and plasticity index. Kutch soils with non-plastic fines exhibited low liquefaction resistance and showed increased resistance at higher FC; however, for sands with plastic fines, PI rather than FC controlled the cyclic degradation. Saturated sandy soils with non-plastic fines exhibited lower shear stress mobilisation, higher pore pressure and larger degradation as compared to sands with clay content. In series II, the settlement characteristics of moist samples at constant normal stress revealed decreased axial deformation and increased mobilised shear stress with increased FC and PI. Silty-sands exhibited higher deformations and larger strength as compared to clayey-sands. The EMDCSS tests at saturated and moist conditions revealed Kutch soils to be prone to liquefaction and large settlements, respectively.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"17 1","pages":"1762 - 1785"},"PeriodicalIF":1.3,"publicationDate":"2021-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48538515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-06DOI: 10.1080/17486025.2021.1974579
Fatemeh Sabbaqzade, M. Keramati, Hossein Moradi Moghaddam, Pouria Hamidian
ABSTRACT Studying the effect of different percentages of mixing rice straw fibres (RSF) on the compressive strength (CS) of collapsible soils stabilised with different amounts of cement through performing unconfined compressive strength (UCS) test and standard compaction test (SCT) form the basis of laboratory research in this project. The purpose of the use of natural fibres in this study is to achieve sustainability objectives in geotechnical engineering. The variable parameters of the study include the fibre content (0%, 0.25%, 0.5% and 1%), the cement content (0%, 4%, 8% and 12%), and the curing time (0, 7, and 28 days). In the sample containing only 1% of fibres, increasing the amount of cement from 0% to 12% improved the compressive strength by 172.38% and decreased the failure strain (FS) by 68.10%. The response surface methodology (RSM) was also conducted in the present study to identify the influence rules of cement content, curing time, fibre content, and their interactions on CS and FS. RSM is considered a confident method, since in both models, the P-Values are less than 0.0001, and the R2 index for CS and FS equals 0.9893 and 0.9776, respectively.
{"title":"Evaluation of the mechanical behaviour of cement - stabilised collapsible soils treated with natural fibres","authors":"Fatemeh Sabbaqzade, M. Keramati, Hossein Moradi Moghaddam, Pouria Hamidian","doi":"10.1080/17486025.2021.1974579","DOIUrl":"https://doi.org/10.1080/17486025.2021.1974579","url":null,"abstract":"ABSTRACT Studying the effect of different percentages of mixing rice straw fibres (RSF) on the compressive strength (CS) of collapsible soils stabilised with different amounts of cement through performing unconfined compressive strength (UCS) test and standard compaction test (SCT) form the basis of laboratory research in this project. The purpose of the use of natural fibres in this study is to achieve sustainability objectives in geotechnical engineering. The variable parameters of the study include the fibre content (0%, 0.25%, 0.5% and 1%), the cement content (0%, 4%, 8% and 12%), and the curing time (0, 7, and 28 days). In the sample containing only 1% of fibres, increasing the amount of cement from 0% to 12% improved the compressive strength by 172.38% and decreased the failure strain (FS) by 68.10%. The response surface methodology (RSM) was also conducted in the present study to identify the influence rules of cement content, curing time, fibre content, and their interactions on CS and FS. RSM is considered a confident method, since in both models, the P-Values are less than 0.0001, and the R2 index for CS and FS equals 0.9893 and 0.9776, respectively.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"17 1","pages":"1735 - 1750"},"PeriodicalIF":1.3,"publicationDate":"2021-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47519496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-03DOI: 10.1080/17486025.2019.1573325
Mohammed Khouaouci, Rawaz Dlawar Muhammed, J. Canou, J. Dupla, Ali Bouafia
ABSTRACT The results of a series of displacement-controlled cyclic axial loading tests of model pile in saturated kaolinite clay, carried out in a calibration chamber, are presented. An instrumented pile-probe was used to investigate the evolution of local skin friction and excess pore water pressure during cyclic loading. After a brief description of the experimental setup and the testing procedure, the tests results are presented concerning the response of the probe during installation, initial monotonic axial loading, cyclic loading up to large numbers of cycles (105 cycles) and post-cyclic monotonic axial loading. During cyclic loading, an initial degradation phase of local skin friction followed by a stabilization phase is observed. Generation of excess pore water pressure occurs during the 60 first cycles followed by a dissipation phase. Parametric study showed that, for initial monotonic loadings, maximum tip resistance and local skin friction are proportional to stress level. Furthermore, excess pore water pressure generated during cyclic loading depends both on initial stress level applied to the clay specimen and cyclic displacement amplitude. A peak value of local skin friction resistance has been observed during post-cyclic monotonic loadings.
{"title":"Model pile behavior in calibration chamber under very large number of cycles of axial loading in saturated clay","authors":"Mohammed Khouaouci, Rawaz Dlawar Muhammed, J. Canou, J. Dupla, Ali Bouafia","doi":"10.1080/17486025.2019.1573325","DOIUrl":"https://doi.org/10.1080/17486025.2019.1573325","url":null,"abstract":"ABSTRACT The results of a series of displacement-controlled cyclic axial loading tests of model pile in saturated kaolinite clay, carried out in a calibration chamber, are presented. An instrumented pile-probe was used to investigate the evolution of local skin friction and excess pore water pressure during cyclic loading. After a brief description of the experimental setup and the testing procedure, the tests results are presented concerning the response of the probe during installation, initial monotonic axial loading, cyclic loading up to large numbers of cycles (105 cycles) and post-cyclic monotonic axial loading. During cyclic loading, an initial degradation phase of local skin friction followed by a stabilization phase is observed. Generation of excess pore water pressure occurs during the 60 first cycles followed by a dissipation phase. Parametric study showed that, for initial monotonic loadings, maximum tip resistance and local skin friction are proportional to stress level. Furthermore, excess pore water pressure generated during cyclic loading depends both on initial stress level applied to the clay specimen and cyclic displacement amplitude. A peak value of local skin friction resistance has been observed during post-cyclic monotonic loadings.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"22 3","pages":"331 - 347"},"PeriodicalIF":1.3,"publicationDate":"2021-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/17486025.2019.1573325","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41289800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-24DOI: 10.1080/17486025.2021.1961024
T. Fontoura, Olavo Francisco dos Santos, R. Severo, R. Coutinho
ABSTRACT Mixing cement and soil is a traditional technique used to improve their mechanical properties. Other studies proposed a rational dosage methodology for soil-cement mixtures. This method is based on the void-cement ratio and aimed at obtaining a particular strength level. The present study evaluated the validity of the void-cement ratio (η/Civ) and analysed the stress – strain – strength behaviour of aeolian dune sand from Natal, Brazil, mixed with cement. Isotropically consolidated drained triaxial compression tests (CID-C) were conducted with moulded samples containing 0.0, 2.5, 5.0 and 7.5% cement by weight of dry soil. Void ratios corresponded to three conditions of relative density: loose, medium and dense, with confining stresses of 50, 100, 200 and 300 kPa. The effect of void ratio, cement content and void-cement ratio on the stress-strain-strength behaviour of the mixtures was determined. The results showed that the void-cement ratio is an appropriate parameter to assess the effective strength of the cement-sand mixture studied.
{"title":"Drained behaviour of artificially cemented dune aeolian sand","authors":"T. Fontoura, Olavo Francisco dos Santos, R. Severo, R. Coutinho","doi":"10.1080/17486025.2021.1961024","DOIUrl":"https://doi.org/10.1080/17486025.2021.1961024","url":null,"abstract":"ABSTRACT Mixing cement and soil is a traditional technique used to improve their mechanical properties. Other studies proposed a rational dosage methodology for soil-cement mixtures. This method is based on the void-cement ratio and aimed at obtaining a particular strength level. The present study evaluated the validity of the void-cement ratio (η/Civ) and analysed the stress – strain – strength behaviour of aeolian dune sand from Natal, Brazil, mixed with cement. Isotropically consolidated drained triaxial compression tests (CID-C) were conducted with moulded samples containing 0.0, 2.5, 5.0 and 7.5% cement by weight of dry soil. Void ratios corresponded to three conditions of relative density: loose, medium and dense, with confining stresses of 50, 100, 200 and 300 kPa. The effect of void ratio, cement content and void-cement ratio on the stress-strain-strength behaviour of the mixtures was determined. The results showed that the void-cement ratio is an appropriate parameter to assess the effective strength of the cement-sand mixture studied.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"17 1","pages":"1695 - 1706"},"PeriodicalIF":1.3,"publicationDate":"2021-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48954312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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