Pub Date : 2016-01-02DOI: 10.1080/19375247.2016.1166313
J. Coe, B. Kermani
Foundation length is an important parameter when assessing bridge vulnerability to failures related to scour hazards. As a result, multiple non-destructive testing methods have been developed to evaluate the geometry of unknown foundations, each with their own advantages and disadvantages. Subsurface methods that rely on measurements from boreholes alongside the foundation are often the most robust when evaluating foundation length, particularly for complex foundations (e.g. footings supported on piles). In this study, such a system was developed to evaluate the length of foundations at two bridge sites in Philadelphia using ultrasound acoustic waves (i.e. P-waves). Characteristics of the foundations and the site conditions are summarised as well as the ultrasound system components. The system was lowered in a borehole alongside each foundation as 100 kHz P-waves were generated to develop a reflection image of the pile–soil interface. Foundation length was evaluated based on discontinuity of the reflected signals with depth. This ultrasound system was developed to address inadequacies with borehole radar testing in similar applications related to unknown foundations. In particular, borehole radar has limited capabilities in clayey soil profiles, where high values of electrical conductivity limit radar signal strength. A commercial borehole radar system (MALÅ 250 MHz ProEx) was therefore utilised at both bridge sites to provide a comparison of results using both systems.
{"title":"Comparison of Borehole Ultrasound and borehole radar in evaluating the length of two unknown bridge foundations","authors":"J. Coe, B. Kermani","doi":"10.1080/19375247.2016.1166313","DOIUrl":"https://doi.org/10.1080/19375247.2016.1166313","url":null,"abstract":"Foundation length is an important parameter when assessing bridge vulnerability to failures related to scour hazards. As a result, multiple non-destructive testing methods have been developed to evaluate the geometry of unknown foundations, each with their own advantages and disadvantages. Subsurface methods that rely on measurements from boreholes alongside the foundation are often the most robust when evaluating foundation length, particularly for complex foundations (e.g. footings supported on piles). In this study, such a system was developed to evaluate the length of foundations at two bridge sites in Philadelphia using ultrasound acoustic waves (i.e. P-waves). Characteristics of the foundations and the site conditions are summarised as well as the ultrasound system components. The system was lowered in a borehole alongside each foundation as 100 kHz P-waves were generated to develop a reflection image of the pile–soil interface. Foundation length was evaluated based on discontinuity of the reflected signals with depth. This ultrasound system was developed to address inadequacies with borehole radar testing in similar applications related to unknown foundations. In particular, borehole radar has limited capabilities in clayey soil profiles, where high values of electrical conductivity limit radar signal strength. A commercial borehole radar system (MALÅ 250 MHz ProEx) was therefore utilised at both bridge sites to provide a comparison of results using both systems.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129918565","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 : 2016-01-02DOI: 10.1080/19375247.2016.1166314
C. Olgun, G. A. Bowers
Using energy piles is becoming an increasingly popular method for economically and efficiently accessing shallow geothermal energy for heating and cooling buildings. Energy piles are deep foundation elements integrated with fluid circulation tubes, which allow them to serve as heat exchangers in addition to their traditional role of structural support. In this study, the use of energy piles for deicing of bridge decks was investigated. Temperature-induced stresses that develop as a result of soil-pile interaction during heat exchange operations need to be evaluated for adequate design of energy piles. This paper presents the results from a series of full-scale field tests on an energy pile during bridge deck deicing operations. The resulting axial strains and stresses in the pile are presented and discussed within the context of soil-pile interaction under thermal loads. Conclusions are drawn about the behavior of energy piles and recommendations are given for their use as heat exchangers.
{"title":"Experimental investigation of energy pile response for bridge deck deicing applications","authors":"C. Olgun, G. A. Bowers","doi":"10.1080/19375247.2016.1166314","DOIUrl":"https://doi.org/10.1080/19375247.2016.1166314","url":null,"abstract":"Using energy piles is becoming an increasingly popular method for economically and efficiently accessing shallow geothermal energy for heating and cooling buildings. Energy piles are deep foundation elements integrated with fluid circulation tubes, which allow them to serve as heat exchangers in addition to their traditional role of structural support. In this study, the use of energy piles for deicing of bridge decks was investigated. Temperature-induced stresses that develop as a result of soil-pile interaction during heat exchange operations need to be evaluated for adequate design of energy piles. This paper presents the results from a series of full-scale field tests on an energy pile during bridge deck deicing operations. The resulting axial strains and stresses in the pile are presented and discussed within the context of soil-pile interaction under thermal loads. Conclusions are drawn about the behavior of energy piles and recommendations are given for their use as heat exchangers.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116040546","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 : 2016-01-02DOI: 10.1080/19375247.2016.1148373
A. Bradshaw
This paper presents an inversion scheme to estimate the distribution of load in a deep foundation from the load–movement curve measured at the head. The method may be useful in situations where static load tests have been performed on test piles that are not instrumented with strain gages or telltales, or the instrumentation data are unreliable. An inversion approach is described in detail that includes a non-linear ‘t–z’ analysis combined with a genetic algorithm that is used to optimise the solutions. The inversion approach is tested using three high-quality pile load test cases from the literature. The pile load distributions estimated from the inversions were in generally good agreement with the measured data. The inversion approach was also effective identifying the ‘true’ load distribution in a pile where residual loads were present.
{"title":"Pile load transfer from static load test inversion","authors":"A. Bradshaw","doi":"10.1080/19375247.2016.1148373","DOIUrl":"https://doi.org/10.1080/19375247.2016.1148373","url":null,"abstract":"This paper presents an inversion scheme to estimate the distribution of load in a deep foundation from the load–movement curve measured at the head. The method may be useful in situations where static load tests have been performed on test piles that are not instrumented with strain gages or telltales, or the instrumentation data are unreliable. An inversion approach is described in detail that includes a non-linear ‘t–z’ analysis combined with a genetic algorithm that is used to optimise the solutions. The inversion approach is tested using three high-quality pile load test cases from the literature. The pile load distributions estimated from the inversions were in generally good agreement with the measured data. The inversion approach was also effective identifying the ‘true’ load distribution in a pile where residual loads were present.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"114 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126905450","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 : 2016-01-02DOI: 10.1080/19375247.2016.1169361
K. R. Johnson
Thermal integrity profiling (TIP) is the most recent non-destructive test method to gain widespread popularity in post-construction evaluation of drilled shafts. The allure lies in its ability to detect anomalies across the entire cross-section of a shaft as well as provide a measure of lateral cage alignment. Similarly remarkable, early developments showed that the shape of a temperature profile (with depth) matched closely with the shape of the shaft, thus allowing for a fairly straightforward interpretation of data. Immediately apparent however, was that the relationship between shape and temperature was with two major exceptions: (1) near the ends of the shaft where heat can escape both radially and longitudinally and (2) where drastic changes in the surroundings are encountered (e.g. soil to water, soil to air). Today, methods for analyzing these portions of data exist, but can often involve tedious levels of parameter iterations and trial-and-error thermal modeling. This is particularly true when the effects of time are not well understood. A comparison of model and field results is presented to provide further insight into these types of temperature distributions and to address the difficulties associated with their analysis. This paper shows how thermal modeling can be used to track the effects of time on analysis, and concludes with case studies that demonstrate the findings.
{"title":"Analyzing thermal integrity profiling data for drilled shaft evaluation","authors":"K. R. Johnson","doi":"10.1080/19375247.2016.1169361","DOIUrl":"https://doi.org/10.1080/19375247.2016.1169361","url":null,"abstract":"Thermal integrity profiling (TIP) is the most recent non-destructive test method to gain widespread popularity in post-construction evaluation of drilled shafts. The allure lies in its ability to detect anomalies across the entire cross-section of a shaft as well as provide a measure of lateral cage alignment. Similarly remarkable, early developments showed that the shape of a temperature profile (with depth) matched closely with the shape of the shaft, thus allowing for a fairly straightforward interpretation of data. Immediately apparent however, was that the relationship between shape and temperature was with two major exceptions: (1) near the ends of the shaft where heat can escape both radially and longitudinally and (2) where drastic changes in the surroundings are encountered (e.g. soil to water, soil to air). Today, methods for analyzing these portions of data exist, but can often involve tedious levels of parameter iterations and trial-and-error thermal modeling. This is particularly true when the effects of time are not well understood. A comparison of model and field results is presented to provide further insight into these types of temperature distributions and to address the difficulties associated with their analysis. This paper shows how thermal modeling can be used to track the effects of time on analysis, and concludes with case studies that demonstrate the findings.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133857524","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 : 2016-01-02DOI: 10.1080/19375247.2016.1150680
{"title":"DFI Journal Underwriters","authors":"","doi":"10.1080/19375247.2016.1150680","DOIUrl":"https://doi.org/10.1080/19375247.2016.1150680","url":null,"abstract":"","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132932942","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 : 2015-07-03DOI: 10.1179/1937525515Y.0000000009
B. Turner, S. Brandenberg
Studies recently conducted by the authors and others have demonstrated that relatively simple equivalent-static analysis (ESA) procedures can adequately predict the response of bridge foundations to lateral spreading for design purposes assuming that the lateral spreading displacement demand is known or can be estimated. However, an important aspect of the analysis that remains to be addressed is how to account for the restraining force provided by foundations when the laterally spreading ground does not have a finite, measurable out-of-plane width. This study addresses this problem in the context of two parallel, adjacent bridges crossing the Colorado River in Mexico that were subjected to a broad field of laterally spreading ground during the 2010 Mw 7.2 El Mayor–Cucapah earthquake. Two-dimensional finite element analyses (FEA) are used to quantify the influence that the presence of each bridge had on the lateral spreading demand for the opposite bridge. The results show that the relatively stiff foundations of the first bridge provided a ‘shielding’ effect to the second bridge, significantly reducing the demand compared to the magnitude of the free-field lateral spreading observed at the site.
作者和其他人最近进行的研究表明，相对简单的等效静力分析(ESA)程序可以充分预测桥梁基础对横向扩展的响应，以达到设计目的，假设横向扩展位移需求是已知的或可以估计的。然而，分析中仍有待解决的一个重要方面是，当横向扩展的地面没有有限的、可测量的面外宽度时，如何考虑地基提供的约束力。本研究以横跨墨西哥科罗拉多河的两座平行的相邻桥梁为背景，解决了这一问题，这两座桥梁在2010年m7.2 El Mayor-Cucapah地震中遭受了大面积的横向扩展地面。二维有限元分析(FEA)用于量化每座桥梁的存在对对面桥梁横向扩展需求的影响。结果表明，第一座桥梁相对坚硬的基础为第二座桥梁提供了“屏蔽”效应，与现场观察到的自由场横向扩展幅度相比，显著降低了需求。
{"title":"Pile pinning and interaction of adjacent foundations during lateral spreading","authors":"B. Turner, S. Brandenberg","doi":"10.1179/1937525515Y.0000000009","DOIUrl":"https://doi.org/10.1179/1937525515Y.0000000009","url":null,"abstract":"Studies recently conducted by the authors and others have demonstrated that relatively simple equivalent-static analysis (ESA) procedures can adequately predict the response of bridge foundations to lateral spreading for design purposes assuming that the lateral spreading displacement demand is known or can be estimated. However, an important aspect of the analysis that remains to be addressed is how to account for the restraining force provided by foundations when the laterally spreading ground does not have a finite, measurable out-of-plane width. This study addresses this problem in the context of two parallel, adjacent bridges crossing the Colorado River in Mexico that were subjected to a broad field of laterally spreading ground during the 2010 Mw 7.2 El Mayor–Cucapah earthquake. Two-dimensional finite element analyses (FEA) are used to quantify the influence that the presence of each bridge had on the lateral spreading demand for the opposite bridge. The results show that the relatively stiff foundations of the first bridge provided a ‘shielding’ effect to the second bridge, significantly reducing the demand compared to the magnitude of the free-field lateral spreading observed at the site.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124051053","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 : 2015-07-03DOI: 10.1179/1937525515Y.0000000008
F. Bagheri, M. E. El Naggar
Helical piles and anchors are installed by applying torque to the pile head. Their application as a foundation option has gained popularity in recent years because of their intrinsic advantages of rapid installation with minimal vibration and noise, and the development of powerful hydraulic driving heads. In spite of extensive research that investigated the behavior of helical piles and anchors, discrepancies between predictions and actual observations of axial behavior of helical piles installed in clay still exist. This is, in large part, because much of previous research involved installation of helical pile models in remolded (reconstituted) cohesive materials rather than natural soil deposits. Since the strength of the remolded materials does not change significantly, the effects of installation cannot be distinguished in remolded materials. In this study, full scale uplift and compression load tests data are analyzed and different failure patterns have been investigated for helical piles and anchors installed in structured clays. The research findings indicate that the behavior of the helical piles and anchors is significantly affected by the degree of soil disturbance induced by penetration of pile shaft and helices. In addition, back-calculated undrained shear strength mobilized by different sections of pile revealed that, for helical piles and anchors installed in structured clay, the undrained shear strength should be reduced to account for installation disturbance.
{"title":"Effects of installation disturbance on behavior of multi-helix piles in structured clays","authors":"F. Bagheri, M. E. El Naggar","doi":"10.1179/1937525515Y.0000000008","DOIUrl":"https://doi.org/10.1179/1937525515Y.0000000008","url":null,"abstract":"Helical piles and anchors are installed by applying torque to the pile head. Their application as a foundation option has gained popularity in recent years because of their intrinsic advantages of rapid installation with minimal vibration and noise, and the development of powerful hydraulic driving heads. In spite of extensive research that investigated the behavior of helical piles and anchors, discrepancies between predictions and actual observations of axial behavior of helical piles installed in clay still exist. This is, in large part, because much of previous research involved installation of helical pile models in remolded (reconstituted) cohesive materials rather than natural soil deposits. Since the strength of the remolded materials does not change significantly, the effects of installation cannot be distinguished in remolded materials. In this study, full scale uplift and compression load tests data are analyzed and different failure patterns have been investigated for helical piles and anchors installed in structured clays. The research findings indicate that the behavior of the helical piles and anchors is significantly affected by the degree of soil disturbance induced by penetration of pile shaft and helices. In addition, back-calculated undrained shear strength mobilized by different sections of pile revealed that, for helical piles and anchors installed in structured clay, the undrained shear strength should be reduced to account for installation disturbance.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121855835","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 : 2015-07-03DOI: 10.1179/1937525515Y.0000000007
Jie-Ru Chen, F. Kulhawy
The authors have presented an interesting study on interpreting the results of static load tests on augered cast-in-place (ACIP) piles, including numerical evaluations of several load test interpretation criteria. Both warrant query and comment. The discussers have conducted some similar prior studies that can be used for comparison. This discussion first will compare the authors and discussers databases and then will focus on the initial response of the load-displacement curve, interpreted failure load, extrapolation of load test data, and recommendations on selection of methods. The focus will be on comparing the Davisson, slope tangent in compression, and L1–L2 methods.
{"title":"Discussion of ‘Interpretation of augered cast in place pile capacity using static loading tests’ by A. W. Stuedlein*, S. C. Reddy and T. M. Evans, The Journal of the Deep Foundation Institute, 8(1), 2014","authors":"Jie-Ru Chen, F. Kulhawy","doi":"10.1179/1937525515Y.0000000007","DOIUrl":"https://doi.org/10.1179/1937525515Y.0000000007","url":null,"abstract":"The authors have presented an interesting study on interpreting the results of static load tests on augered cast-in-place (ACIP) piles, including numerical evaluations of several load test interpretation criteria. Both warrant query and comment. The discussers have conducted some similar prior studies that can be used for comparison. This discussion first will compare the authors and discussers databases and then will focus on the initial response of the load-displacement curve, interpreted failure load, extrapolation of load test data, and recommendations on selection of methods. The focus will be on comparing the Davisson, slope tangent in compression, and L1–L2 methods.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115935586","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 : 2015-07-03DOI: 10.1179/1937525515Y.0000000006
A. Stuedlein, S. C. Reddy, T. M. Evans
This closure addresses the comments made by the discussers to a previously published paper on the interpretation of failure loads from static loading tests on augered cast-in-place piles. In this closure, it is shown that there were no data or interpretation problems as postulated by the discussers. It is shown that: the ratio of elastic and initial compression slopes depends on the slenderness ration, the L2 capacity depends on the magnitude of displacement imposed, and the L2 capacity relative to the Davisson capacity is a function of the axial stiffness. This closure points to the important role of slenderness ratio (which serves as a proxy for axial stiffness) on the interpretation of failure loads.
{"title":"Closure to the discussion of ‘interpretation of augered cast-in-place pile capacity using static loading tests’","authors":"A. Stuedlein, S. C. Reddy, T. M. Evans","doi":"10.1179/1937525515Y.0000000006","DOIUrl":"https://doi.org/10.1179/1937525515Y.0000000006","url":null,"abstract":"This closure addresses the comments made by the discussers to a previously published paper on the interpretation of failure loads from static loading tests on augered cast-in-place piles. In this closure, it is shown that there were no data or interpretation problems as postulated by the discussers. It is shown that: the ratio of elastic and initial compression slopes depends on the slenderness ration, the L2 capacity depends on the magnitude of displacement imposed, and the L2 capacity relative to the Davisson capacity is a function of the axial stiffness. This closure points to the important role of slenderness ratio (which serves as a proxy for axial stiffness) on the interpretation of failure loads.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132792789","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 : 2015-07-03DOI: 10.1080/19375247.2015.1123382
Anne Lemnitzer, Timothy C. Siegel
We are happy to close out the 2015 with an excellent issue that primarily focuses on unique performance aspects of pile foundations under axial and lateral loading. Issue 2 opens with a Technical Note by Franz providing guidance for drafting specifications for ground improvement. This document is a result of the work performed by DFI’s ground improvement committee. The note can be used as a checklist for selecting the most appropriate and efficient ground improvement technique considering available geotechnical information, operational constraints, desired performance requirements such as target bearing capacity and maximum allowable settlements, the influence of seismicity, and the impact of ground water regimes for the specific project needs. The next two articles discuss a previously published DFI manuscript by Stuedlein et al., entitled “Interpretation of augered cast in place pile capacity using static loading Tests”. Chen and Kulhawy offer a different opinion on the pile load displacement interpretation based on their independent pile database. Stuedlein closes this discussion with additional information on how his research team interpreted their own load test data, pointing out the importance of the pile slenderness ratio and how this ratio can be used as a proxy for axial stiffness in determining the pile failure load. In the fourth article, Bagheri and El Naggar present their analysis of a series of full scale uplift and compression load test data of helical piles and anchors installed in structured clays. Test variations include the numbers of helices and different helix diameters, as well as the embedment depths, and the diversity of natural clay deposits in which the specimens were installed. Findings of this research study indicate that the behavior of the helical piles and anchors is significantly influenced by the degree of soil disturbance introduced by the penetration of the pile shaft and helices. As a result of the disturbance, the undrained shear strength mobilized by the uppermost helix decreases and should be reduced to account for installation effects. The fifth article is the winner of the 2014 DFI student paper competition entitled “Pile pinning and interaction of adjacent foundations during lateral spreading” by Turner, a Ph.D. candidate at the University of California, Los Angeles, and his advisor Brandenberg. They present the results of a PEER funded case study of two parallel, adjacent bridges crossing the Colorado River in Mexico that were subjected to a broad field of laterally-spreading ground during the 2010 M 7.2 El Mayor-Cucapah earthquake. Turner and Brandenberg use equivalent static analysis procedures combined with 2D FEM algorithms to evaluate the lateral spreading demand on the bridges as well as the influence of pinning effects and geometric configurations (e.g. shielding effects of opposite bridges). Findings of this study show that the length and width of the lateral spread feature relative to the size o
{"title":"Editors’ Note","authors":"Anne Lemnitzer, Timothy C. Siegel","doi":"10.1080/19375247.2015.1123382","DOIUrl":"https://doi.org/10.1080/19375247.2015.1123382","url":null,"abstract":"We are happy to close out the 2015 with an excellent issue that primarily focuses on unique performance aspects of pile foundations under axial and lateral loading. Issue 2 opens with a Technical Note by Franz providing guidance for drafting specifications for ground improvement. This document is a result of the work performed by DFI’s ground improvement committee. The note can be used as a checklist for selecting the most appropriate and efficient ground improvement technique considering available geotechnical information, operational constraints, desired performance requirements such as target bearing capacity and maximum allowable settlements, the influence of seismicity, and the impact of ground water regimes for the specific project needs. The next two articles discuss a previously published DFI manuscript by Stuedlein et al., entitled “Interpretation of augered cast in place pile capacity using static loading Tests”. Chen and Kulhawy offer a different opinion on the pile load displacement interpretation based on their independent pile database. Stuedlein closes this discussion with additional information on how his research team interpreted their own load test data, pointing out the importance of the pile slenderness ratio and how this ratio can be used as a proxy for axial stiffness in determining the pile failure load. In the fourth article, Bagheri and El Naggar present their analysis of a series of full scale uplift and compression load test data of helical piles and anchors installed in structured clays. Test variations include the numbers of helices and different helix diameters, as well as the embedment depths, and the diversity of natural clay deposits in which the specimens were installed. Findings of this research study indicate that the behavior of the helical piles and anchors is significantly influenced by the degree of soil disturbance introduced by the penetration of the pile shaft and helices. As a result of the disturbance, the undrained shear strength mobilized by the uppermost helix decreases and should be reduced to account for installation effects. The fifth article is the winner of the 2014 DFI student paper competition entitled “Pile pinning and interaction of adjacent foundations during lateral spreading” by Turner, a Ph.D. candidate at the University of California, Los Angeles, and his advisor Brandenberg. They present the results of a PEER funded case study of two parallel, adjacent bridges crossing the Colorado River in Mexico that were subjected to a broad field of laterally-spreading ground during the 2010 M 7.2 El Mayor-Cucapah earthquake. Turner and Brandenberg use equivalent static analysis procedures combined with 2D FEM algorithms to evaluate the lateral spreading demand on the bridges as well as the influence of pinning effects and geometric configurations (e.g. shielding effects of opposite bridges). Findings of this study show that the length and width of the lateral spread feature relative to the size o","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122436118","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：