Pub Date : 2018-12-01DOI: 10.18690/ACTAGEOTECHSLOV.15.2.74-80.2018
Cui Qiang, China Transformation Eng. Dep. Beijing, Zhenhua Zhang, Rui-ming Tong, Zhong Lv
In order to revel the effect of the geometric size parameter of a circular shallow foundation on its uplift capacity in loess soil, the shaft diameter d, the enlarge angle of the slab θ and the embedment ratio ht/D of the shallow foundation were chosen to determine the field test schemes using the orthogonal test method. The field uplift tests were carried out on the tested foundations at a site located in Gangu County, Tianshui City, Gansu Province, China. The uplift load vs. the outward displacement curves of all the test foundations were recorded using automatic electronic measuring instrument. The test results revel that all the uplift load vs. outward displacement curves of the tested foundations are non-linear and take on an obvious three stages. Through the analysis on all the uplift load vs. outward displacement curves, the uplift capacities are achieved using the L1-L2 graphic method. By analyzing the relationship between the uplift capacities and the geometric parameters (enlarge angle of slab θ, the embedment ratio ht/D and the shaft diameter d) of the tested foundations, it is concluded that the uplift capacities of all the tested foundations increase with the increase of θ, ht/D and d, and the influencing degree of the three geometric factors on the uplift capacity of the circular shallow foundation is θ > d > ht/D. C. Qiang et al.: The effects of the geometric parameters of a circular shallow foundation on its uplift bearing capacity in loess soil Zhenhua Zhang (corresponding author) Hefei University of Technology, School of Civil Engineering Hefei 230009, China E-mail: zenithzhang@sina.com Zhongcheng Lv Jinshuitan Hydropower Plant of State Grid, Zhejiang electric power co., Ltd. Lishui 323000, China
为了揭示圆形浅基础几何尺寸参数对黄土地基上拔能力的影响，采用正交试验法，选取浅基础轴直径d、底板放大角度θ和埋深比ht/ d确定现场试验方案。现场隆升试验是在中国甘肃省天水市甘谷县的试验地基上进行的。采用自动电子测量仪记录各试验地基的上拔荷载与向外位移曲线。试验结果表明，试验地基的上拔荷载与向外位移曲线均呈非线性变化，呈现明显的三阶段变化。通过对所有上拔荷载与向外位移曲线的分析，采用L1-L2图解法得到了上拔能力。通过分析试验基础的抗拔能力与几何参数(底板放大角θ、埋深比ht/D、井径D)的关系，得出试验基础的抗拔能力随着θ、ht/D、D的增大而增大，3个几何因素对圆形浅基础抗拔能力的影响程度为θ > D > ht/D。张振华(通讯作者)合肥工业大学土木工程学院合肥230009 E-mail: zenithzhang@sina.com吕中成国网浙江电力股份有限公司金水滩水电站浙江丽水323000
{"title":"The effects of the geometric parameters of a circular shallow foundation on its uplift bearing capacity in loess soil","authors":"Cui Qiang, China Transformation Eng. Dep. Beijing, Zhenhua Zhang, Rui-ming Tong, Zhong Lv","doi":"10.18690/ACTAGEOTECHSLOV.15.2.74-80.2018","DOIUrl":"https://doi.org/10.18690/ACTAGEOTECHSLOV.15.2.74-80.2018","url":null,"abstract":"In order to revel the effect of the geometric size parameter of a circular shallow foundation on its uplift capacity in loess soil, the shaft diameter d, the enlarge angle of the slab θ and the embedment ratio ht/D of the shallow foundation were chosen to determine the field test schemes using the orthogonal test method. The field uplift tests were carried out on the tested foundations at a site located in Gangu County, Tianshui City, Gansu Province, China. The uplift load vs. the outward displacement curves of all the test foundations were recorded using automatic electronic measuring instrument. The test results revel that all the uplift load vs. outward displacement curves of the tested foundations are non-linear and take on an obvious three stages. Through the analysis on all the uplift load vs. outward displacement curves, the uplift capacities are achieved using the L1-L2 graphic method. By analyzing the relationship between the uplift capacities and the geometric parameters (enlarge angle of slab θ, the embedment ratio ht/D and the shaft diameter d) of the tested foundations, it is concluded that the uplift capacities of all the tested foundations increase with the increase of θ, ht/D and d, and the influencing degree of the three geometric factors on the uplift capacity of the circular shallow foundation is θ > d > ht/D. C. Qiang et al.: The effects of the geometric parameters of a circular shallow foundation on its uplift bearing capacity in loess soil Zhenhua Zhang (corresponding author) Hefei University of Technology, School of Civil Engineering Hefei 230009, China E-mail: zenithzhang@sina.com Zhongcheng Lv Jinshuitan Hydropower Plant of State Grid, Zhejiang electric power co., Ltd. Lishui 323000, China","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43539023","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 : 2018-12-01DOI: 10.18690/actageotechslov.15.2.81-91.2018
J. Stacho
Drilled Displacement System (DDS) piles are an innovative technology for pile foundations. These DDS piles are created by rotary drilling with a simultaneous full displacement of the soil in a horizontal direction. The optimal design of DDS piles can be obtained in sandy soils and fine-grained soils that allow for a horizontal displacement, which causes an increase in the shaft’s resistance. This article deals with the use of Cavity Expansion Theory (CET) for a complex analysis of DDS piles. This method makes it possible to take into account the impact of the technology in pile design. A general view of the CET is presented and is described step by step for the solution of the present problem. The results of the calculations are compared and analysed with the results of three instrumented static load tests. The analyses include a comparison of the load-settlement curve as well as the load distribution over the pile’s length, which was measured using strain gauges. The results of the analyses show very good agreement between the calculations and the measurements. The difference between the calculated and measured load-settlement curves did not exceed a 10% degree of accuracy. The possibilities for the future use of CET are also discussed. J. Stacho: The design of drilled displacement system piles using the cavity expansion theory
{"title":"The design of drilled displacement system piles using the cavity expansion theory","authors":"J. Stacho","doi":"10.18690/actageotechslov.15.2.81-91.2018","DOIUrl":"https://doi.org/10.18690/actageotechslov.15.2.81-91.2018","url":null,"abstract":"Drilled Displacement System (DDS) piles are an innovative technology for pile foundations. These DDS piles are created by rotary drilling with a simultaneous full displacement of the soil in a horizontal direction. The optimal design of DDS piles can be obtained in sandy soils and fine-grained soils that allow for a horizontal displacement, which causes an increase in the shaft’s resistance. This article deals with the use of Cavity Expansion Theory (CET) for a complex analysis of DDS piles. This method makes it possible to take into account the impact of the technology in pile design. A general view of the CET is presented and is described step by step for the solution of the present problem. The results of the calculations are compared and analysed with the results of three instrumented static load tests. The analyses include a comparison of the load-settlement curve as well as the load distribution over the pile’s length, which was measured using strain gauges. The results of the analyses show very good agreement between the calculations and the measurements. The difference between the calculated and measured load-settlement curves did not exceed a 10% degree of accuracy. The possibilities for the future use of CET are also discussed. J. Stacho: The design of drilled displacement system piles using the cavity expansion theory","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43535986","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 : 2018-12-01DOI: 10.18690/ACTAGEOTECHSLOV.15.2.38-46.2018
Zhen Li, Dongdong Zhang, Shuangxi Zhao
Deep-buried engineering and test results show that hard rocks behave as part of an elastoplastic damage coupling process. The coupling effect can contribute to the weakness of the surrounding rocks and the extension of the water channels. As a result, the coupled elastoplastic damage model is the basis for a stability analysis in deep engineering. In this paper loading and unloading tests were conducted on T2b marble in the Jinping II hydropower station. Based on the tests the effects of the confining pressure on the strength, the failure strain and the dilation were analyzed. According to the plastic shear failure and the parameters weakness mechanism, the damage-evolution function reflecting the weakness character, the loading function and the plastic potential function regarding plastic hardening were proposed. The activation of the damage and plastic process was then studied. The coupled elastoplastic damage model was finally established. Through simulating the test curve, the proposed model was verified. This model could play an important role in the stability analysis of deep-buried hard-rock engineering. Z. Li et al.: Loading and unloading test of hard rock and its elastoplastic damage coupling model
{"title":"Loading and unloading test of hard rock and its elastoplastic damage coupling model","authors":"Zhen Li, Dongdong Zhang, Shuangxi Zhao","doi":"10.18690/ACTAGEOTECHSLOV.15.2.38-46.2018","DOIUrl":"https://doi.org/10.18690/ACTAGEOTECHSLOV.15.2.38-46.2018","url":null,"abstract":"Deep-buried engineering and test results show that hard rocks behave as part of an elastoplastic damage coupling process. The coupling effect can contribute to the weakness of the surrounding rocks and the extension of the water channels. As a result, the coupled elastoplastic damage model is the basis for a stability analysis in deep engineering. In this paper loading and unloading tests were conducted on T2b marble in the Jinping II hydropower station. Based on the tests the effects of the confining pressure on the strength, the failure strain and the dilation were analyzed. According to the plastic shear failure and the parameters weakness mechanism, the damage-evolution function reflecting the weakness character, the loading function and the plastic potential function regarding plastic hardening were proposed. The activation of the damage and plastic process was then studied. The coupled elastoplastic damage model was finally established. Through simulating the test curve, the proposed model was verified. This model could play an important role in the stability analysis of deep-buried hard-rock engineering. Z. Li et al.: Loading and unloading test of hard rock and its elastoplastic damage coupling model","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46945261","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 : 2018-12-01DOI: 10.18690/ACTAGEOTECHSLOV.15.2.16-37.2018
V. Vukadin, Slovenčeva Ljubljana Slovenija Envireonment, V. Jovičić, Ljubljana Slovenia Environment Slovenčeva
Materials known in the literature as hard soils and soft rocks are widely spread, natural materials that are commonly encountered in engineering practise. It was demonstrated that some of these materials can be described through the general theoretical framework for structured soils set by Cotecchia and Chandler [14], which takes into account the structure as an intrinsic property present in all natural geological materials. Based on laboratory results and existing theoretical frameworks, the development of a constitutive model for structured materials was carried out. The model formulated in strain space named BRICK [27, 29] was chosen as the base model and was further developed by adding features to model both the structure and the processes of destructuring. The new model was named S_BRICK and was first presented on a conceptual level, in which the typical results of modelling structured and structureless (reconstituted) materials on different stress paths were compared within the solutions of the Cotecchia and Chandler [14] theoretical framework. The S_BRICK model was validated on three materials, i.e., Pappadai clay, North-Sea clay and Corinth marl, thus covering a wide range of natural, structured materials. The results showed that S_BRICK was able to successfully model the stress-strain behaviour typical for hard-soil and soft-rock materials, in general.
{"title":"S_BRICK: a constitutive model for soils and soft rocks","authors":"V. Vukadin, Slovenčeva Ljubljana Slovenija Envireonment, V. Jovičić, Ljubljana Slovenia Environment Slovenčeva","doi":"10.18690/ACTAGEOTECHSLOV.15.2.16-37.2018","DOIUrl":"https://doi.org/10.18690/ACTAGEOTECHSLOV.15.2.16-37.2018","url":null,"abstract":"Materials known in the literature as hard soils and soft rocks are widely spread, natural materials that are commonly encountered in engineering practise. It was demonstrated that some of these materials can be described through the general theoretical framework for structured soils set by Cotecchia and Chandler [14], which takes into account the structure as an intrinsic property present in all natural geological materials. Based on laboratory results and existing theoretical frameworks, the development of a constitutive model for structured materials was carried out. The model formulated in strain space named BRICK [27, 29] was chosen as the base model and was further developed by adding features to model both the structure and the processes of destructuring. The new model was named S_BRICK and was first presented on a conceptual level, in which the typical results of modelling structured and structureless (reconstituted) materials on different stress paths were compared within the solutions of the Cotecchia and Chandler [14] theoretical framework. The S_BRICK model was validated on three materials, i.e., Pappadai clay, North-Sea clay and Corinth marl, thus covering a wide range of natural, structured materials. The results showed that S_BRICK was able to successfully model the stress-strain behaviour typical for hard-soil and soft-rock materials, in general.","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46843695","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 : 2018-12-01DOI: 10.18690/ACTAGEOTECHSLOV.15.2.47-57.2018
G. Misir
Soil anchors are generally used for structures that are subjected to pullout forces, such as offshore floating bodies, transmission towers, structures requiring lateral resistance or submerged platforms etc. Multi-plate anchors are used as a foundation that apply either large compression or tension forces using a number of plates welded along a central shaft. These anchors that have more than one plate have a complex interaction between the adjacent plates due to over applying stress zones. Therefore, this interaction affects the failure mechanism and the uplift capacity of the system. However, no thorough numerical analyses have been performed to determine the ultimate pullout loads of multi-plate anchors. By far the majority of the research has been directed towards the tensile uplift behavior of one-plate single anchor. Estimating the uplift capacity by using a practical design method that is obtained from a numerical analysis of two-plate anchors in sand is described in this paper. This method can be used more confidently by design engineers to estimate the pullout capacity of two-plate anchors under tension loading. The theoretical results are compared with the numerical data and acceptable values are obtained. G. Misir: Predicting the uplift capacity of vertically located two-plate anchors
{"title":"Predicting the uplift capacity of vertically located two-plate anchors","authors":"G. Misir","doi":"10.18690/ACTAGEOTECHSLOV.15.2.47-57.2018","DOIUrl":"https://doi.org/10.18690/ACTAGEOTECHSLOV.15.2.47-57.2018","url":null,"abstract":"Soil anchors are generally used for structures that are subjected to pullout forces, such as offshore floating bodies, transmission towers, structures requiring lateral resistance or submerged platforms etc. Multi-plate anchors are used as a foundation that apply either large compression or tension forces using a number of plates welded along a central shaft. These anchors that have more than one plate have a complex interaction between the adjacent plates due to over applying stress zones. Therefore, this interaction affects the failure mechanism and the uplift capacity of the system. However, no thorough numerical analyses have been performed to determine the ultimate pullout loads of multi-plate anchors. By far the majority of the research has been directed towards the tensile uplift behavior of one-plate single anchor. Estimating the uplift capacity by using a practical design method that is obtained from a numerical analysis of two-plate anchors in sand is described in this paper. This method can be used more confidently by design engineers to estimate the pullout capacity of two-plate anchors under tension loading. The theoretical results are compared with the numerical data and acceptable values are obtained. G. Misir: Predicting the uplift capacity of vertically located two-plate anchors","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45896992","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 : 2018-06-01DOI: 10.18690/ACTAGEOTECHSLOV.15.1.17-27.2018
Jinchao Wang, Chuanying Wang, Z. Han, Yiteng Wang, Xinjian Tang
Conventional geostress measurement methods are limited by deficiencies including the measurable depth, the complexity, and the long duration of operation. To address these problems and achieve the measurement of geostress in deep wells under conditions of complex high pressures and high temperatures, we propose a new measurement method for geostress based on an integrated drilling and optical microscopy system. Its innovative integrated structure eliminates the problems associated with complex procedures and depth limits, and avoids rock creep caused by long delays, significantly improving the accuracy and range of the measurements. It works by using microscopic imaging and direct contact probes to capture the changes of a borehole’s cross-sectional outlines before and after stress relief. The resulting images are analyzed with search circles to obtain the positions of probe apices, which can be fitted into ellipses that describe the outlines, and calculate the state of the stress. The validity and accuracy of the method was verified by in-door tests and field applications in the ZK1 borehole. The results show that: (1) the integrated system can be used to measure micrometer-grade deformations; (2) the search-circle approach can accurately obtain the positions of probe apices; and (3) the stress measurement method based on the system is accurate and feasible.
{"title":"A geostress measurement method based on an integrated drilling and optical microscopic imaging system","authors":"Jinchao Wang, Chuanying Wang, Z. Han, Yiteng Wang, Xinjian Tang","doi":"10.18690/ACTAGEOTECHSLOV.15.1.17-27.2018","DOIUrl":"https://doi.org/10.18690/ACTAGEOTECHSLOV.15.1.17-27.2018","url":null,"abstract":"Conventional geostress measurement methods are limited by deficiencies including the measurable depth, the complexity, and the long duration of operation. To address these problems and achieve the measurement of geostress in deep wells under conditions of complex high pressures and high temperatures, we propose a new measurement method for geostress based on an integrated drilling and optical microscopy system. Its innovative integrated structure eliminates the problems associated with complex procedures and depth limits, and avoids rock creep caused by long delays, significantly improving the accuracy and range of the measurements. It works by using microscopic imaging and direct contact probes to capture the changes of a borehole’s cross-sectional outlines before and after stress relief. The resulting images are analyzed with search circles to obtain the positions of probe apices, which can be fitted into ellipses that describe the outlines, and calculate the state of the stress. The validity and accuracy of the method was verified by in-door tests and field applications in the ZK1 borehole. The results show that: (1) the integrated system can be used to measure micrometer-grade deformations; (2) the search-circle approach can accurately obtain the positions of probe apices; and (3) the stress measurement method based on the system is accurate and feasible.","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48815530","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 : 2018-06-01DOI: 10.18690/ACTAGEOTECHSLOV.15.1.55-75.2018
Liu Feicheng, Zhang Jianjing, Y. Shijie, Cao Licong
A simplified method for evaluating a pile-supported embankment reinforced with geosynthetic (PGRS embankment) is proposed in this paper. The method takes into account not only the arching effect, the membrane effect of the deflected geosynthetic, and the subsoil reaction, but also the pile head settlement, which makes the method applicable for floating piles, as well as piles seated on a firm soil layer. The settlement of the subsoil surface is considered to consist of two parts: (a) the settlement of the subsoil surface equals that of the pile cap with no deformation in geosynthetic yet; (b) the subsoil surface subsides along with the geosynthetic deforming, and the deflected geosynthetic being considered as catenary shaped. The formula for the maximum differential settlement between the subsoil surface and the piles is worked out by analyzing the force equilibrium of the geosynthetic and the stress-strain relationship of the geosynthetic at the edge of the pile cap. The comparison of the calculated results with the observed data and the six current analytical methods has been implemented to verify the proposed method. The influence of the tensile stiffness of the geosynthetic, compression modulus of soft soil, soft soil thickness, embankment height, internal friction angle of the embankment fill and the pile spacing on the subsoil reaction, the stress concentration ratio (SCR) and the tension of the geosynthetic are investigated using the proposed method. The influence significance of these factors has been investigated using the evaluation theory of binary variance analysis for the non-repeatability tests, which helps optimize the design of the PGRS embankment.
{"title":"A simplified method to analyze pile-supported and geosynthetic-reinforced embankments and the influence significance analysis of the design parameters","authors":"Liu Feicheng, Zhang Jianjing, Y. Shijie, Cao Licong","doi":"10.18690/ACTAGEOTECHSLOV.15.1.55-75.2018","DOIUrl":"https://doi.org/10.18690/ACTAGEOTECHSLOV.15.1.55-75.2018","url":null,"abstract":"A simplified method for evaluating a pile-supported embankment reinforced with geosynthetic (PGRS embankment) is proposed in this paper. The method takes into account not only the arching effect, the membrane effect of the deflected geosynthetic, and the subsoil reaction, but also the pile head settlement, which makes the method applicable for floating piles, as well as piles seated on a firm soil layer. The settlement of the subsoil surface is considered to consist of two parts: (a) the settlement of the subsoil surface equals that of the pile cap with no deformation in geosynthetic yet; (b) the subsoil surface subsides along with the geosynthetic deforming, and the deflected geosynthetic being considered as catenary shaped. The formula for the maximum differential settlement between the subsoil surface and the piles is worked out by analyzing the force equilibrium of the geosynthetic and the stress-strain relationship of the geosynthetic at the edge of the pile cap. The comparison of the calculated results with the observed data and the six current analytical methods has been implemented to verify the proposed method. The influence of the tensile stiffness of the geosynthetic, compression modulus of soft soil, soft soil thickness, embankment height, internal friction angle of the embankment fill and the pile spacing on the subsoil reaction, the stress concentration ratio (SCR) and the tension of the geosynthetic are investigated using the proposed method. The influence significance of these factors has been investigated using the evaluation theory of binary variance analysis for the non-repeatability tests, which helps optimize the design of the PGRS embankment.","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46074342","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 : 2018-06-01DOI: 10.18690/ACTAGEOTECHSLOV.15.1.77-85.2018
A. Gurbuz
An accurate prediction of the load capacity of a laterally loaded pile at a permissible displacement is an important concern at the design stage. In contrast to many sophisticated methods, Broms’ method based on moment equilibrium has been preferred by engineers to predict the load capacities of laterally loaded piles due to both its simplicity and because it is established on a way of hand calculation. However, Broms’ method typically overestimates a pile’s lateral load capacity as it requires a constant coefficient of horizontal subgrade reaction (nh) into analyses, regardless of the magnitude of the pile’s top displacement. In this study, modified coefficients of subgrade reactions(nh*) that are sensitive to the pile’s top displacement in cohesionless soils are first proposed to improve the performance level of Broms’ method for the prediction of the load capacity of a laterally loaded pile as the pile’s top displacement increases. The modified values of nh* are calibrated using 45 independently free-head, single-driven, full-scale pile tests from 23 sites in cohesionless soils. It is demonstrated that Broms’ method with nh* would correctly estimate a pile’s lateral load-deflection behavior with accuracy levels similar to more complicated methods.
{"title":"Modified coefficient of subgrade reaction to laterally loaded piles","authors":"A. Gurbuz","doi":"10.18690/ACTAGEOTECHSLOV.15.1.77-85.2018","DOIUrl":"https://doi.org/10.18690/ACTAGEOTECHSLOV.15.1.77-85.2018","url":null,"abstract":"An accurate prediction of the load capacity of a laterally loaded pile at a permissible displacement is an important concern at the design stage. In contrast to many sophisticated methods, Broms’ method based on moment equilibrium has been preferred by engineers to predict the load capacities of laterally loaded piles due to both its simplicity and because it is established on a way of hand calculation. However, Broms’ method typically overestimates a pile’s lateral load capacity as it requires a constant coefficient of horizontal subgrade reaction (nh) into analyses, regardless of the magnitude of the pile’s top displacement. In this study, modified coefficients of subgrade reactions(nh*) that are sensitive to the pile’s top displacement in cohesionless soils are first proposed to improve the performance level of Broms’ method for the prediction of the load capacity of a laterally loaded pile as the pile’s top displacement increases. The modified values of nh* are calibrated using 45 independently free-head, single-driven, full-scale pile tests from 23 sites in cohesionless soils. It is demonstrated that Broms’ method with nh* would correctly estimate a pile’s lateral load-deflection behavior with accuracy levels similar to more complicated methods.","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46290828","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 : 2018-06-01DOI: 10.18690/actageotechslov.15.1.3-15.2018
A. Cabalar, M. M. Khalaf, Z. Karabash
Bender-element (BE) tests were conducted on clay-sand mixtures to investigate the variation of small strain-shear modulus (Gmax) with the sand content and the physical characteristics (size, shape) of the sand grains in the mixtures. Three different gradations (0.6–0.3 mm, 1.0–0.6 mm and 2.0–1.0 mm) of sands having distinct shapes (rounded, angular) were added to a low-plasticity clay with mixture ratios of 0% (clean clay), 10%, 20%, 30%, 40%, and 50%. For the purposes of performing a correlation analysis, unconfined compression (UC) tests were also carried out on the same specimens. The tests indicated that both the Gmax and unconfined compressive strength (qu) values of the specimens with angular sand grains were measured to be lower than those with rounded sand grains, for all sizes and percentages. As the percentage of sand in the mixture increases, the Gmax values increase, while the qu values decrease. The results further suggested that the Gmax values decrease as the qu values decreases as the size of the sand grains reduces.
{"title":"Shear modules of claysand mixtures using bender element test","authors":"A. Cabalar, M. M. Khalaf, Z. Karabash","doi":"10.18690/actageotechslov.15.1.3-15.2018","DOIUrl":"https://doi.org/10.18690/actageotechslov.15.1.3-15.2018","url":null,"abstract":"Bender-element (BE) tests were conducted on clay-sand mixtures to investigate the variation of small strain-shear modulus (Gmax) with the sand content and the physical characteristics (size, shape) of the sand grains in the mixtures. Three different gradations (0.6–0.3 mm, 1.0–0.6 mm and 2.0–1.0 mm) of sands having distinct shapes (rounded, angular) were added to a low-plasticity clay with mixture ratios of 0% (clean clay), 10%, 20%, 30%, 40%, and 50%. For the purposes of performing a correlation analysis, unconfined compression (UC) tests were also carried out on the same specimens. The tests indicated that both the Gmax and unconfined compressive strength (qu) values of the specimens with angular sand grains were measured to be lower than those with rounded sand grains, for all sizes and percentages. As the percentage of sand in the mixture increases, the Gmax values increase, while the qu values decrease. The results further suggested that the Gmax values decrease as the qu values decreases as the size of the sand grains reduces.","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45952916","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 : 2018-06-01DOI: 10.18690/ACTAGEOTECHSLOV.15.1.87-99.2018
Jiwei Li, Changfu Wei, Yanlin Zhao, P. Nanning
A general analytical solution is developed for the one-dimensional consolidation problem of unsaturated soil under various time-dependent loading conditions based on a differential transformation method (DTM). In particular, analytical solutions are obtained for different relationships between the coefficients in the governing equations for unsaturated soil consolidation. The Fourier series expansion technique is adopted to account for both the continuous differentiable loading and the periodic piecewise loading. A comparison between the results of the current solution and the existing theoretical solution indicates that the proposed solution yields excellent results, while it is straightforward to obtain the analytical solution of the unsaturated consolidation problems. It was also found that the variations in the coefficients in the governing equations can significantly influence the dissipation of both the excess pore-air pressure and the excess pore-water pressure, though the magnitudes of their variations are different.
{"title":"A general analytical solution to the one-dimensional consolidation problem for unsaturated soil under various loading conditions","authors":"Jiwei Li, Changfu Wei, Yanlin Zhao, P. Nanning","doi":"10.18690/ACTAGEOTECHSLOV.15.1.87-99.2018","DOIUrl":"https://doi.org/10.18690/ACTAGEOTECHSLOV.15.1.87-99.2018","url":null,"abstract":"A general analytical solution is developed for the one-dimensional consolidation problem of unsaturated soil under various time-dependent loading conditions based on a differential transformation method (DTM). In particular, analytical solutions are obtained for different relationships between the coefficients in the governing equations for unsaturated soil consolidation. The Fourier series expansion technique is adopted to account for both the continuous differentiable loading and the periodic piecewise loading. A comparison between the results of the current solution and the existing theoretical solution indicates that the proposed solution yields excellent results, while it is straightforward to obtain the analytical solution of the unsaturated consolidation problems. It was also found that the variations in the coefficients in the governing equations can significantly influence the dissipation of both the excess pore-air pressure and the excess pore-water pressure, though the magnitudes of their variations are different.","PeriodicalId":50897,"journal":{"name":"Acta Geotechnica Slovenica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49501767","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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