Pub Date : 2020-10-13DOI: 10.37308/dfijnl.20181008.189
B. Fellenius
A static test was performed on a 610-mm diameter, 10 m long CFA pile installed through 3 m of clay and sand and into a thick deposit of lacustrine clay. The loading procedure included prolonged load-holding and an unloading-reloading event, which adversely affected the interpretations of the strain records and demonstrated the inadvisability of not performing a test with equal load-increments and equal load-holding durations and avoiding all unloading-reloading sequences. The pile was strain-gage instrumented at three levels and the recorded strains were used to calculate the pile axial stiffness and determine the load distributions for the applied load. Back-calculations using effective stress analysis were fitted to strain-gage determined load distributions and were then used in simulating the measured pile-head load-movement of the test pile.
{"title":"Analysis of Strain-gage Records from a Static Loading Test on a CFA Pile","authors":"B. Fellenius","doi":"10.37308/dfijnl.20181008.189","DOIUrl":"https://doi.org/10.37308/dfijnl.20181008.189","url":null,"abstract":"A static test was performed on a 610-mm diameter, 10 m long CFA pile installed through 3 m of clay and sand and into a thick deposit of lacustrine clay. The loading procedure included prolonged load-holding and an unloading-reloading event, which adversely affected the interpretations of the strain records and demonstrated the inadvisability of not performing a test with equal load-increments and equal load-holding durations and avoiding all unloading-reloading sequences. The pile was strain-gage instrumented at three levels and the recorded strains were used to calculate the pile axial stiffness and determine the load distributions for the applied load. Back-calculations using effective stress analysis were fitted to strain-gage determined load distributions and were then used in simulating the measured pile-head load-movement of the test pile.","PeriodicalId":339795,"journal":{"name":"DFI Journal: The Journal of the Deep Foundations Institute","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131033739","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 : 2020-10-13DOI: 10.37308/dfijnl.20190930.210
A. Bateman
Accurate estimates of pile settlement are key for efficient design of axially loaded piles. Calculations of pile settlement can be simplified using one-dimensional “t-z” curves describing pile settlement at a certain depth as a function of side friction. In the realm of this simplified framework, theoretical “t-z” curves can be derived by substituting an attenuation function describing the variation of shear stress with distance from the pile, into a soil constitutive model relating shear strain to shear stress, then integrating with respect to distance to get the settlement at the pile circumference due to an applied shear stress. A handful of analytical “t-z” curves are available in the literature using the concentric cylinder model to define an attenuation function; these include solutions for linear-elastic, power-law and hyperbolic constitutive models. However, radially homogeneous soil has often been assumed, ignoring the effect of the pile installation resulting in unconservative calculations of pile settlement. This paper considers the installation of the pile, resulting in a radially variable shear modulus distribution in the surrounding soil. A radial inhomogeneity correction factor has been developed for selected constitutive models based on two simplified functions for the soil inhomogeneity, which can be applied to the previously derived “t-z” curves produced assuming radially homogeneous soil. The performance of this simplified method is investigated.
{"title":"Theoretical \"t-z\" Curves for Piles in Radially Inhomogeneous Soil","authors":"A. Bateman","doi":"10.37308/dfijnl.20190930.210","DOIUrl":"https://doi.org/10.37308/dfijnl.20190930.210","url":null,"abstract":"Accurate estimates of pile settlement are key for efficient design of axially loaded piles. Calculations of pile settlement can be simplified using one-dimensional “t-z” curves describing pile settlement at a certain depth as a function of side friction. In the realm of this simplified framework, theoretical “t-z” curves can be derived by substituting an attenuation function describing the variation of shear stress with distance from the pile, into a soil constitutive model relating shear strain to shear stress, then integrating with respect to distance to get the settlement at the pile circumference due to an applied shear stress. A handful of analytical “t-z” curves are available in the literature using the concentric cylinder model to define an attenuation function; these include solutions for linear-elastic, power-law and hyperbolic constitutive models. However, radially homogeneous soil has often been assumed, ignoring the effect of the pile installation resulting in unconservative calculations of pile settlement. This paper considers the installation of the pile, resulting in a radially variable shear modulus distribution in the surrounding soil. A radial inhomogeneity correction factor has been developed for selected constitutive models based on two simplified functions for the soil inhomogeneity, which can be applied to the previously derived “t-z” curves produced assuming radially homogeneous soil. The performance of this simplified method is investigated.","PeriodicalId":339795,"journal":{"name":"DFI Journal: The Journal of the Deep Foundations Institute","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121606271","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 : 2020-10-13DOI: 10.37308/dfijnl.20200602.219
E. Tolba
This paper presents a soil interaction sensitivity analysis using a three-dimensional finite element analysis of existing quay wall diaphragm at the east port in Port Said in northeast Egypt. The main objective of this analysis was to study the influence of soft clay layer parameters on the results of FEM analyses on an existing quay wall. At first, background information on the soil strata used in this study is introduced. Then, a full description of the existing diaphragm quay wall located at the east port is provided. A parametric study was carried out for three different soil profiles using strain-hardening constitutive model (HSM) parameters and clay layer thickness, and the results are presented and discussed. The recommended constitutive soil parameters of the marine clay determined using the HSM for the optimization analysis of the quay walls in that location are also presented.
{"title":"Sensitivity Analysis of Soft Clay Parameters on an Existing Quay Wall at the East Port in Port Said, Egypt","authors":"E. Tolba","doi":"10.37308/dfijnl.20200602.219","DOIUrl":"https://doi.org/10.37308/dfijnl.20200602.219","url":null,"abstract":"This paper presents a soil interaction sensitivity analysis using a three-dimensional finite element analysis of existing quay wall diaphragm at the east port in Port Said in northeast Egypt. The main objective of this analysis was to study the influence of soft clay layer parameters on the results of FEM analyses on an existing quay wall. At first, background information on the soil strata used in this study is introduced. Then, a full description of the existing diaphragm quay wall located at the east port is provided. A parametric study was carried out for three different soil profiles using strain-hardening constitutive model (HSM) parameters and clay layer thickness, and the results are presented and discussed. The recommended constitutive soil parameters of the marine clay determined using the HSM for the optimization analysis of the quay walls in that location are also presented.","PeriodicalId":339795,"journal":{"name":"DFI Journal: The Journal of the Deep Foundations Institute","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131262023","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 : 2020-10-13DOI: 10.37308/dfijnl.20191120.212
M. Souri
The results of five centrifuge models were used to evaluate the response of pile-supported wharves subjected to inertial and liquefaction-induced lateral spreading loads. The centrifuge models contained pile groups that were embedded in rockfill dikes over layers of loose to dense sand and were shaken by a series of ground motions. The p-y curves were back-calculated for both dynamic and static loading from centrifuge data and were compared against commonly used American Petroleum Institute p-y relationships. It was found that liquefaction in loose sand resulted in a significant reduction in ultimate soil resistance. It was also found that incorporating p-multipliers that are proportional to the pore water pressure ratio in granular materials is adequate for estimating pile demands in pseudo-static analysis. The unique contribution of this study is that the piles in these tests were subjected to combined effects of inertial loads from the superstructure and kinematic loads from liquefaction-induced lateral spreading.
{"title":"Development of Experimental P-Y Curves from Centrifuge Tests for Piles Subjected to Static Loading and Liquefaction-Induced Lateral Spreading","authors":"M. Souri","doi":"10.37308/dfijnl.20191120.212","DOIUrl":"https://doi.org/10.37308/dfijnl.20191120.212","url":null,"abstract":"The results of five centrifuge models were used to evaluate the response of pile-supported wharves subjected to inertial and liquefaction-induced lateral spreading loads. The centrifuge models contained pile groups that were embedded in rockfill dikes over layers of loose to dense sand and were shaken by a series of ground motions. The p-y curves were back-calculated for both dynamic and static loading from centrifuge data and were compared against commonly used American Petroleum Institute p-y relationships. It was found that liquefaction in loose sand resulted in a significant reduction in ultimate soil resistance. It was also found that incorporating p-multipliers that are proportional to the pore water pressure ratio in granular materials is adequate for estimating pile demands in pseudo-static analysis. The unique contribution of this study is that the piles in these tests were subjected to combined effects of inertial loads from the superstructure and kinematic loads from liquefaction-induced lateral spreading.","PeriodicalId":339795,"journal":{"name":"DFI Journal: The Journal of the Deep Foundations Institute","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116745002","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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