Pub Date : 2021-01-01DOI: 10.18690/actageotechslov.18.1.2-14.2021
Arefeh Arabaninezhad, A. Fakher
Deep excavations in urban areas impose deformation to adjacent structures; hence the reliability of deformation analysis for the real deep excavation projects is very important to be assessed. In this study a framework is presented for the use of reliability methods in deformation analysis of deep urban excavations. The suggested framework is applied for 5 real deep excavation projects implemented during last 10 years. All studied cases were recognized as projects of high importance in urban areas, and were monitored during the excavation process. A non-probabilistic reliability analysis procedure, Random set method, in combination with finite element numerical modeling is applied to obtain the probability of unsatisfactory performance for each case. The reliability analysis results are confirmed by field observations and measurements. Typical results for the probability of analytical deformations exceeding the acceptable values along with the site observations and measured displacements for 5 real deep excavation projects show that the reliability analysis could be a beneficial tool for designer. It is concluded that applying the suggested framework in the design stage of deep excavation projects may lead to design more appropriate systems compared to common deterministic design methods.
{"title":"A framework for the use of reliability methods in deep urban excavations analysis","authors":"Arefeh Arabaninezhad, A. Fakher","doi":"10.18690/actageotechslov.18.1.2-14.2021","DOIUrl":"https://doi.org/10.18690/actageotechslov.18.1.2-14.2021","url":null,"abstract":"Deep excavations in urban areas impose deformation to adjacent structures; hence the reliability of deformation analysis for the real deep excavation projects is very important to be assessed. In this study a framework is presented for the use of reliability methods in deformation analysis of deep urban excavations. The suggested framework is applied for 5 real deep excavation projects implemented during last 10 years. All studied cases were recognized as projects of high importance in urban areas, and were monitored during the excavation process. A non-probabilistic reliability analysis procedure, Random set method, in combination with finite element numerical modeling is applied to obtain the probability of unsatisfactory performance for each case. The reliability analysis results are confirmed by field observations and measurements. Typical results for the probability of analytical deformations exceeding the acceptable values along with the site observations and measured displacements for 5 real deep excavation projects show that the reliability analysis could be a beneficial tool for designer. It is concluded that applying the suggested framework in the design stage of deep excavation projects may lead to design more appropriate systems compared to common deterministic design methods.","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67766614","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 : 2021-01-01DOI: 10.18690/actageotechslov.18.2.15-28.2022
A. Babaei, M. Ghazavi, N. Ganjian
In this research a series of experimental tests were performed to investigate the effects of nano TiO2 (NT) on the triaxial behavior of cemented clayey sand (with variable amounts of kaolinite). To reduce the number of experiments, time and cost of research, the design and assessment of the experiments were performed using the response surface method (RSM). The amount of used NT was 0-4 wt% of cement, and the amounts of cement and kaolinite were 3-9 wt% and 10-30 wt% of soil respectively. The consolidated drained (CD) triaxial tests were performed for the confining pressures of 100, 300 and 600 kPa. The results of these tests showed that the amount of kaolinite clay at 20 % has the largest effect on the peak deviator stress and friction angle, but the soil cohesion has an ascending trend at 10-30 % kaolinite clay. The amount of cement in the range of 3-9 % causes an increase in the peak-deviator stress, shear strength parameters and the brittleness index. Also, the use of NT in a desirable amount (2 %) causes an increase in the peak deviator stress and the shear strength parameters.
{"title":"GanjianInvestigating the shear properties of cemented clayey sand with a nano TiO2 additive","authors":"A. Babaei, M. Ghazavi, N. Ganjian","doi":"10.18690/actageotechslov.18.2.15-28.2022","DOIUrl":"https://doi.org/10.18690/actageotechslov.18.2.15-28.2022","url":null,"abstract":"In this research a series of experimental tests were performed to investigate the effects of nano TiO2 (NT) on the triaxial behavior of cemented clayey sand (with variable amounts of kaolinite). To reduce the number of experiments, time and cost of research, the design and assessment of the experiments were performed using the response surface method (RSM). The amount of used NT was 0-4 wt% of cement, and the amounts of cement and kaolinite were 3-9 wt% and 10-30 wt% of soil respectively. The consolidated drained (CD) triaxial tests were performed for the confining pressures of 100, 300 and 600 kPa. The results of these tests showed that the amount of kaolinite clay at 20 % has the largest effect on the peak deviator stress and friction angle, but the soil cohesion has an ascending trend at 10-30 % kaolinite clay. The amount of cement in the range of 3-9 % causes an increase in the peak-deviator stress, shear strength parameters and the brittleness index. Also, the use of NT in a desirable amount (2 %) causes an increase in the peak deviator stress and the shear strength parameters.","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67767147","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 : 2021-01-01DOI: 10.18690/actageotechslov.18.2.44-55.2022
E. Meziane, Ismail Benessalah, A. Arab
Abstract A stability analysis of soils prone to liquefaction based on their undrained shear-strength characteristics is an indispensable challenge in earthquake geotechnical engineering. This paper presents a laboratory study of the influence of relative density on the cyclic behavior of Chlef sand. The experimental program includes undrained, triaxial cyclic tests that were carried out for three different relative densities (Dr = 15, 50 and to 65 %) with various cyclic stress ratios (CSR = 0.15, 0.25 and 0.35). All the samples were consolidated under one initial effective confining pressure σ'c = 100 kPa. The main results show that the increases in the relative density led to significant increases in the shear strength established by an increase in the number of cycles and with an exponential rise. In contrast, it was demonstrated that the number of cycles was decreased when increasing the cyclic stress ratio due to the shearing frequency. The two main effects of the studied parameters did not have the same influence on the cyclic undrained response of the sandy soil submitted to seismic loading: an increase of the deviatoric stress due to the high relative density that participates in the increase of the loading capacity of the compacted soils by minimizing the void ratios, and an increase of the pore-water pressure that has a negative effect on the liquefaction of the soil. From the results obtained, it can be concluded that these two mechanisms led to a global increase of the maximum shearing stress.
{"title":"An insight into the liquefaction resistance of sand using cyclic undrained triaxial tests: Effect of the relative density and the loading amplitude","authors":"E. Meziane, Ismail Benessalah, A. Arab","doi":"10.18690/actageotechslov.18.2.44-55.2022","DOIUrl":"https://doi.org/10.18690/actageotechslov.18.2.44-55.2022","url":null,"abstract":"Abstract A stability analysis of soils prone to liquefaction based on their undrained shear-strength characteristics is an indispensable challenge in earthquake geotechnical engineering. This paper presents a laboratory study of the influence of relative density on the cyclic behavior of Chlef sand. The experimental program includes undrained, triaxial cyclic tests that were carried out for three different relative densities (Dr = 15, 50 and to 65 %) with various cyclic stress ratios (CSR = 0.15, 0.25 and 0.35). All the samples were consolidated under one initial effective confining pressure σ'c = 100 kPa. The main results show that the increases in the relative density led to significant increases in the shear strength established by an increase in the number of cycles and with an exponential rise. In contrast, it was demonstrated that the number of cycles was decreased when increasing the cyclic stress ratio due to the shearing frequency. The two main effects of the studied parameters did not have the same influence on the cyclic undrained response of the sandy soil submitted to seismic loading: an increase of the deviatoric stress due to the high relative density that participates in the increase of the loading capacity of the compacted soils by minimizing the void ratios, and an increase of the pore-water pressure that has a negative effect on the liquefaction of the soil. From the results obtained, it can be concluded that these two mechanisms led to a global increase of the maximum shearing stress.","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67767221","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 : 2021-01-01DOI: 10.18690/actageotechslov.18.1.15-27.2021
Junran Zhang, Lijin Wang, Tong Jiang, Ren Miao, min Wei
There is a close relationship between tensile strength of soil and crack development, but the tensile stress-strain in full failure process is rarely studied because challenges exist in accurately measuring shear strain using traditional methods. In this paper, we employed a newly developed diametric splitting testing apparatus and particle image velocimetry (PIV) system to study the tensile strength of compacted unsaturated expansive soil with different water contents and initial dry densities. Soil water characteristic curves of compacted expansive soil with different initial dry densities were determined using the filter paper method. Test results show that the tensile strength increases first and then decreases with increasing water content, and there is a critical water content for the peak load vs. water content curve. The diametric splitting test process can be divided into four stages on the basis of the plotted load-displacement curves: a stress contact adjustment stage (I); stress approximately linear increasing stage (II); tensile failure stage (III); and residual stage (IV). Under the same water content, the angle between the major directions of the displacement vector and the major crack decreases with increasing the dry density, especially when the fissure appears. Using the particle image velocimetry technique, the displacement and strain during the test process recorded is helpful for better understanding the soil failure mechanism.
{"title":"Diametric splitting tests on unsaturated expansive soil with different dry densities based on particle image velocimetry technique","authors":"Junran Zhang, Lijin Wang, Tong Jiang, Ren Miao, min Wei","doi":"10.18690/actageotechslov.18.1.15-27.2021","DOIUrl":"https://doi.org/10.18690/actageotechslov.18.1.15-27.2021","url":null,"abstract":"There is a close relationship between tensile strength of soil and crack development, but the tensile stress-strain in full failure process is rarely studied because challenges exist in accurately measuring shear strain using traditional methods. In this paper, we employed a newly developed diametric splitting testing apparatus and particle image velocimetry (PIV) system to study the tensile strength of compacted unsaturated expansive soil with different water contents and initial dry densities. Soil water characteristic curves of compacted expansive soil with different initial dry densities were determined using the filter paper method. Test results show that the tensile strength increases first and then decreases with increasing water content, and there is a critical water content for the peak load vs. water content curve. The diametric splitting test process can be divided into four stages on the basis of the plotted load-displacement curves: a stress contact adjustment stage (I); stress approximately linear increasing stage (II); tensile failure stage (III); and residual stage (IV). Under the same water content, the angle between the major directions of the displacement vector and the major crack decreases with increasing the dry density, especially when the fissure appears. Using the particle image velocimetry technique, the displacement and strain during the test process recorded is helpful for better understanding the soil failure mechanism.","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67766577","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 : 2021-01-01DOI: 10.18690/actageotechslov.18.1.65-78.2021
A. Mazaheri, M. Komasi, Majid Veisi, M. Nasiri
The precise study of the response of earth dams to earthquakes is one of the most complex issues in the field of soil structures. In this research, dynamic analysis of earth dam structures (a case study: Doyraj dam in the west of Iran) have been performed using 2D Finite Difference Method (2D F.D.M.). The aim of this study is to investigate accelerations, lateral (horizontal) and vertical displacements (i.e. settlements) due to earthquake occurrence. The results of dynamic analysis indicate that the performance of the dam is satisfactory for each one of the seismic scenarios considered in this investigation. The maximum settlements at the dam crest is considerably smaller than that of the dam freeboard, with maximum value of 540 mm, which is comparable to recommendation of the Department of Safety of Dams (DSOD). Depth of sliding surfaces is better shown in the Finn model, and the settlements based on the Finn model is about 2.5 times higher than that of Mohr model. In contrast to what is commonly accepted about earthquake acceleration (the increase in earthquake acceleration from the base to the top of the dam), it cannot generalize to all cases, and it can be limited to very strong dams or can be related to poor earthquakes.
{"title":"Dynamic analysis of earth dam using numerical method – a case study: Doyraj earth dam","authors":"A. Mazaheri, M. Komasi, Majid Veisi, M. Nasiri","doi":"10.18690/actageotechslov.18.1.65-78.2021","DOIUrl":"https://doi.org/10.18690/actageotechslov.18.1.65-78.2021","url":null,"abstract":"The precise study of the response of earth dams to earthquakes is one of the most complex issues in the field of soil structures. In this research, dynamic analysis of earth dam structures (a case study: Doyraj dam in the west of Iran) have been performed using 2D Finite Difference Method (2D F.D.M.). The aim of this study is to investigate accelerations, lateral (horizontal) and vertical displacements (i.e. settlements) due to earthquake occurrence. The results of dynamic analysis indicate that the performance of the dam is satisfactory for each one of the seismic scenarios considered in this investigation. The maximum settlements at the dam crest is considerably smaller than that of the dam freeboard, with maximum value of 540 mm, which is comparable to recommendation of the Department of Safety of Dams (DSOD). Depth of sliding surfaces is better shown in the Finn model, and the settlements based on the Finn model is about 2.5 times higher than that of Mohr model. In contrast to what is commonly accepted about earthquake acceleration (the increase in earthquake acceleration from the base to the top of the dam), it cannot generalize to all cases, and it can be limited to very strong dams or can be related to poor earthquakes.","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67766720","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 : 2021-01-01DOI: 10.18690/actageotechslov.18.2.29-43.2022
A. Abiodun, Z. Nalbantoglu
Soft soils have a high compressibility, and low shear strength, and constructions on such soils often require the use of ground-improvement techniques. This paper compares the use of an electrokinetic (EK) treatment of soft soils using the ionic solutions calcium chloride and sodium carbonate. The effects of the ionic-solution type, the EK-treatment duration, the cation exchange capacity (CEC), the specific surface area (Sa), the pH, the electrical conductivity (σ), and the ionic strength (Is) were considered in this study. Examining the parameters and evaluating their effects on soil behavior are difficult and complex. The design of experiments (DOE) software program was used to evaluate the effects of the parameters and determine the significant input factors for the EK treatment on soft soils. The analysis and optimization of the data produced the threshold values using the design-expert® software. In this study, the EK-treated soil with CEC = 4.9 meq 100/g, Sa = 4.5 m2/g , pH = 9.5, σ = 6.0 S/m, Is = 1.55·10-4 mol/L, and electrolyte-type setup of CaCl2-Na2CO3 gave better soil strengthening. The gain in strength is attributed to the flocculation and aggregation of the EK-treated soil particles. The analysis of the data by DOE indicated that it could be used to assess the significant effects of the input factors on the unconfined compressive strength, qu of the EK-treated soft soils.
软土具有高压缩性和低抗剪强度，在这种土壤上的建筑通常需要使用地基改良技术。本文比较了氯化钙离子溶液和碳酸钠离子溶液对软土的电动处理效果。考虑了离子溶液类型、ek处理时间、阳离子交换容量(CEC)、比表面积(Sa)、pH、电导率(σ)和离子强度(Is)等因素的影响。检验这些参数并评价它们对土壤特性的影响是困难和复杂的。利用试验设计(DOE)软件程序对各参数的影响进行了评价，确定了EK处理软土的重要输入因子。使用design-expert®软件对数据进行分析和优化，产生阈值。CEC = 4.9 meq 100/g, Sa = 4.5 m2/g, pH = 9.5， σ = 6.0 S/m, Is = 1.55·10-4 mol/L，电解型CaCl2-Na2CO3对土壤的强化效果较好。强度的增加归因于经ek处理的土壤颗粒的絮凝和聚集。DOE数据分析表明，可用于评价输入因子对ekk处理软土无侧限抗压强度qu的显著影响。
{"title":"Electrokinetic treatment of soft soils: experimental study and numerical models","authors":"A. Abiodun, Z. Nalbantoglu","doi":"10.18690/actageotechslov.18.2.29-43.2022","DOIUrl":"https://doi.org/10.18690/actageotechslov.18.2.29-43.2022","url":null,"abstract":"Soft soils have a high compressibility, and low shear strength, and constructions on such soils often require the use of ground-improvement techniques. This paper compares the use of an electrokinetic (EK) treatment of soft soils using the ionic solutions calcium chloride and sodium carbonate. The effects of the ionic-solution type, the EK-treatment duration, the cation exchange capacity (CEC), the specific surface area (Sa), the pH, the electrical conductivity (σ), and the ionic strength (Is) were considered in this study. Examining the parameters and evaluating their effects on soil behavior are difficult and complex. The design of experiments (DOE) software program was used to evaluate the effects of the parameters and determine the significant input factors for the EK treatment on soft soils. The analysis and optimization of the data produced the threshold values using the design-expert® software. In this study, the EK-treated soil with CEC = 4.9 meq 100/g, Sa = 4.5 m2/g , pH = 9.5, σ = 6.0 S/m, Is = 1.55·10-4 mol/L, and electrolyte-type setup of CaCl2-Na2CO3 gave better soil strengthening. The gain in strength is attributed to the flocculation and aggregation of the EK-treated soil particles. The analysis of the data by DOE indicated that it could be used to assess the significant effects of the input factors on the unconfined compressive strength, qu of the EK-treated soft soils.","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67767208","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 : 2021-01-01DOI: 10.18690/actageotechslov.18.2.56-69.2022
M. R. Moghadam, Jahanpour Monfared, M. Parvizi
This study presents a new approach to optimizing the layout of the geogrid layers to achieve the maximum bearing capacity of the strip footing under different loading conditions (Vertical (V), Horizontal (H) and eccentric (M) loads) using a numerical method. To find the best location of the geogrid layers in the current method, the optimum depth of each layer is obtained separately, which was not considered in previous studies. The effects of parameters such as different loading combinations, numbers and layout of geogrid layers on the ultimate bearing capacity of the strip footing have been studied. The results of the analyses are plotted in the form of dimensionless graphs. For different loading combinations, the optimum layout and number of reinforcing layers have been determined. The results show that the presence of the reinforced layers, at the optimum layout, significantly increases the ultimate bearing capacity of the strip footing, especially in the V and VM loading conditions. The optimum number of geogrid layers was different for different loading conditions. Based on the analyses, 7, 4 and 4 geogrid layers were obtained as the optimum number of reinforcement layers for the V, VH and VM loading conditions, respectively. Also, it was found that the position of each layer depends on the number of layers. In this study, the position of the first layer from the foundation (u/B) was varied by increasing the number of reinforcement layers and the loading conditions. In the VM loading condition, the geogrid reinforcement effect on the bearing capacity is more prominent with respect to the VH loading conditions. The increase of the bearing capacity in the VM loading condition at the optimum layout of reinforcement (N = 4) is about 100 %, compared to the bearing capacity of the unreinforced soil.
{"title":"A new approach to optimizing the geogrid layout to maximize the bearing capacity of strip footing","authors":"M. R. Moghadam, Jahanpour Monfared, M. Parvizi","doi":"10.18690/actageotechslov.18.2.56-69.2022","DOIUrl":"https://doi.org/10.18690/actageotechslov.18.2.56-69.2022","url":null,"abstract":"This study presents a new approach to optimizing the layout of the geogrid layers to achieve the maximum bearing capacity of the strip footing under different loading conditions (Vertical (V), Horizontal (H) and eccentric (M) loads) using a numerical method. To find the best location of the geogrid layers in the current method, the optimum depth of each layer is obtained separately, which was not considered in previous studies. The effects of parameters such as different loading combinations, numbers and layout of geogrid layers on the ultimate bearing capacity of the strip footing have been studied. The results of the analyses are plotted in the form of dimensionless graphs. For different loading combinations, the optimum layout and number of reinforcing layers have been determined. The results show that the presence of the reinforced layers, at the optimum layout, significantly increases the ultimate bearing capacity of the strip footing, especially in the V and VM loading conditions. The optimum number of geogrid layers was different for different loading conditions. Based on the analyses, 7, 4 and 4 geogrid layers were obtained as the optimum number of reinforcement layers for the V, VH and VM loading conditions, respectively. Also, it was found that the position of each layer depends on the number of layers. In this study, the position of the first layer from the foundation (u/B) was varied by increasing the number of reinforcement layers and the loading conditions. In the VM loading condition, the geogrid reinforcement effect on the bearing capacity is more prominent with respect to the VH loading conditions. The increase of the bearing capacity in the VM loading condition at the optimum layout of reinforcement (N = 4) is about 100 %, compared to the bearing capacity of the unreinforced soil.","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67767274","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 : 2021-01-01DOI: 10.18690/actageotechslov.18.1.41-54.2021
A. Vakili, S. Zomorodian, A. Totonchi
The accurate predictions of load- deflection response of the pile group are necessary for a safe and economical design. The behavior of piles under the lateral load embedded in soil, is typically analyzed using the Winkler nonlinear springs method. In this method, the soil-pile interaction is modeled by nonlinear p-y curves in a way that the single pile p-y curve is modified using a p-multiplier (Pm) for each row of piles in the group. The average Pm is called the group reduction factor. The Pm factor depends upon the configuration of pile group and the pile spacing (S). The present study was conducted to investigate the effects of various parameters, such as the pile spacing in the group, different layouts and the lateral load angle (Ѳ) change as a new parameter on the Pm factor and group efficiency based on the 1-g model test. The Pm factor is well comparable with the results of the full-scale test on pile group. However, based on the results, the calculated values of the Pm factor for 3×3 pile groups under 2.5-diameter spacing was estimated about 0.38 and under 3.5-diameter spacing was estimated about 0.52, so the calculated values at S/D=3, obtained from interpolation the values of group reduction factor at S/D=2.5 and S/D=3.5, are close to the AASHTO recommendation.
{"title":"Small scale model test on lateral behaviors of pile group in loose silica sand","authors":"A. Vakili, S. Zomorodian, A. Totonchi","doi":"10.18690/actageotechslov.18.1.41-54.2021","DOIUrl":"https://doi.org/10.18690/actageotechslov.18.1.41-54.2021","url":null,"abstract":"The accurate predictions of load- deflection response of the pile group are necessary for a safe and economical design. The behavior of piles under the lateral load embedded in soil, is typically analyzed using the Winkler nonlinear springs method. In this method, the soil-pile interaction is modeled by nonlinear p-y curves in a way that the single pile p-y curve is modified using a p-multiplier (Pm) for each row of piles in the group. The average Pm is called the group reduction factor. The Pm factor depends upon the configuration of pile group and the pile spacing (S). The present study was conducted to investigate the effects of various parameters, such as the pile spacing in the group, different layouts and the lateral load angle (Ѳ) change as a new parameter on the Pm factor and group efficiency based on the 1-g model test. The Pm factor is well comparable with the results of the full-scale test on pile group. However, based on the results, the calculated values of the Pm factor for 3×3 pile groups under 2.5-diameter spacing was estimated about 0.38 and under 3.5-diameter spacing was estimated about 0.52, so the calculated values at S/D=3, obtained from interpolation the values of group reduction factor at S/D=2.5 and S/D=3.5, are close to the AASHTO recommendation.","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67766666","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 : 2021-01-01DOI: 10.18690/actageotechslov.18.1.28-40.2021
A. C. Taiba, Y. Mahmoudi, W. Baille, T. Wichtmann, M. Belkhatir
The threshold silt content is well known as a key parameter affecting the mechanical response of binary granular assemblies considering particle characteristics (size and shape). In this context, the threshold silt content (TSC) is determined from different laboratory tests based on packing density response (emax and emin versus silt content «Sc») and theoretical approaches proposed by several researchers in the specialized published literature using the characteristics of host sand and silt [emax(sand), emin(sand) , emax(silt) , emin(silt) , Gs , Gf and x]. The analysis of the recorded data indicates that the TSC derived from the (emax) curve appears more reliable than that obtained from the (emin) one. Moreover, it is found that the proposed analytical methods are suitable to quantify the threshold silt content (TSC) than that determined experimentally using the packing density (emax and emin). In addition, the test results show that the new introduced ratios [(D50s×As)/(D50f×Af)] and [(Cus×As)/(Cuf×Af)] determined based on particle characteristics (shape and size) appear as appropriate parameters for predicting the threshold silt content (TSC) of sand-silt mixture of the compiled data from the published literature as well as that of the present research related to Chlef sand, Fontainebleau sand and Hostun sand mixed with Chlef silt.
{"title":"Threshold silt content dependency on particle morphology (shape and size) of granular materials: review with new evidence","authors":"A. C. Taiba, Y. Mahmoudi, W. Baille, T. Wichtmann, M. Belkhatir","doi":"10.18690/actageotechslov.18.1.28-40.2021","DOIUrl":"https://doi.org/10.18690/actageotechslov.18.1.28-40.2021","url":null,"abstract":"The threshold silt content is well known as a key parameter affecting the mechanical response of binary granular assemblies considering particle characteristics (size and shape). In this context, the threshold silt content (TSC) is determined from different laboratory tests based on packing density response (emax and emin versus silt content «Sc») and theoretical approaches proposed by several researchers in the specialized published literature using the characteristics of host sand and silt [emax(sand), emin(sand) , emax(silt) , emin(silt) , Gs , Gf and x]. The analysis of the recorded data indicates that the TSC derived from the (emax) curve appears more reliable than that obtained from the (emin) one. Moreover, it is found that the proposed analytical methods are suitable to quantify the threshold silt content (TSC) than that determined experimentally using the packing density (emax and emin). In addition, the test results show that the new introduced ratios [(D50s×As)/(D50f×Af)] and [(Cus×As)/(Cuf×Af)] determined based on particle characteristics (shape and size) appear as appropriate parameters for predicting the threshold silt content (TSC) of sand-silt mixture of the compiled data from the published literature as well as that of the present research related to Chlef sand, Fontainebleau sand and Hostun sand mixed with Chlef silt.","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67766625","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 : 2021-01-01DOI: 10.18690/actageotechslov.18.2.83-104.2022
Güneş Babagiray, S. Akbas, Ö. Anıl
In this study the behavior of buried pipes under impact loading was investigated by forming protective layers with geosynthetics in various combinations in single and double layers. For this purpose, experiments were performed using a HDPE pipe with a 160 mm outer diameter, which is frequently used in the laboratory. In the experiments, Geocell, Geogrid, Geotextile, and Geonet protective layers at a depth of 120 mm were tested by laying Geosynthetic in single and double layers and then tested under the effects of impact loading by using free-weight dropping test apparatus. In the experimental study, the protective layers' energy absorption capacities were calculated by using acceleration measurements over the pipe and then evaluated together with their costs. In the experiments with a single layer Geosynthetic as a protective layer, Geonet's most successful protection structure was a 72.9 % acceleration-damping capacity. In the experiments with the combination of double-layer reinforcement elements, the most successful performance with 88.0 %, in terms of acceleration damping capacity, was obtained from Geocell and Geonet's combination with a thickness of 1 mm at a depth of 50 mm. When all the experiments with single- and double-layer Geosynthetic protective elements were evaluated as an acceleration damping ratio per unit cost, it was found that the optimum application was achieved when using a single-layer Geogrid.
{"title":"Investigation of the impact behavior when using single and double layers of geosynthetics on buried pipe structures","authors":"Güneş Babagiray, S. Akbas, Ö. Anıl","doi":"10.18690/actageotechslov.18.2.83-104.2022","DOIUrl":"https://doi.org/10.18690/actageotechslov.18.2.83-104.2022","url":null,"abstract":"In this study the behavior of buried pipes under impact loading was investigated by forming protective layers with geosynthetics in various combinations in single and double layers. For this purpose, experiments were performed using a HDPE pipe with a 160 mm outer diameter, which is frequently used in the laboratory. In the experiments, Geocell, Geogrid, Geotextile, and Geonet protective layers at a depth of 120 mm were tested by laying Geosynthetic in single and double layers and then tested under the effects of impact loading by using free-weight dropping test apparatus. In the experimental study, the protective layers' energy absorption capacities were calculated by using acceleration measurements over the pipe and then evaluated together with their costs. In the experiments with a single layer Geosynthetic as a protective layer, Geonet's most successful protection structure was a 72.9 % acceleration-damping capacity. In the experiments with the combination of double-layer reinforcement elements, the most successful performance with 88.0 %, in terms of acceleration damping capacity, was obtained from Geocell and Geonet's combination with a thickness of 1 mm at a depth of 50 mm. When all the experiments with single- and double-layer Geosynthetic protective elements were evaluated as an acceleration damping ratio per unit cost, it was found that the optimum application was achieved when using a single-layer Geogrid.","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67767324","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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