Pub Date : 2018-01-02DOI: 10.1080/19375247.2018.1536838
M. Nodine, Paul J. Eggers, Michael P. Walker, Donald E. Aubrecht
The CANALSIDE development in Buffalo, New York serves to revitalise the former site of the Buffalo Memorial Auditorium. The Auditorium was constructed in 1940 and founded on steel H-piles. It was demolished in 2009. The only portion of the Auditorium left intact was a subbasement equipment room with its floor 10 feet below groundwater. A four-story building was proposed to be constructed directly above the subbasement. The loads imparted by the new building would exceed the capacity of the existing piles, so micropiles were drilled through the subbasement floor to support the new building. Drilling through the existing slab and waterproofing system was a challenge due to water control. The concept for the micropiles included drilling from the subbasement roof through a standpipe bolted to the subbasement floor which was used to control water during drilling. The project included other foundation design and construction challenges, including asymmetrical pile cap geometry, water control and obstructions.
{"title":"Micropiles below groundwater at the south auditorium block site, Buffalo, New York","authors":"M. Nodine, Paul J. Eggers, Michael P. Walker, Donald E. Aubrecht","doi":"10.1080/19375247.2018.1536838","DOIUrl":"https://doi.org/10.1080/19375247.2018.1536838","url":null,"abstract":"The CANALSIDE development in Buffalo, New York serves to revitalise the former site of the Buffalo Memorial Auditorium. The Auditorium was constructed in 1940 and founded on steel H-piles. It was demolished in 2009. The only portion of the Auditorium left intact was a subbasement equipment room with its floor 10 feet below groundwater. A four-story building was proposed to be constructed directly above the subbasement. The loads imparted by the new building would exceed the capacity of the existing piles, so micropiles were drilled through the subbasement floor to support the new building. Drilling through the existing slab and waterproofing system was a challenge due to water control. The concept for the micropiles included drilling from the subbasement roof through a standpipe bolted to the subbasement floor which was used to control water during drilling. The project included other foundation design and construction challenges, including asymmetrical pile cap geometry, water control and obstructions.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"111 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116042521","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 : 2018-01-02DOI: 10.1080/19375247.2018.1521608
I. Oweis, S. Anthony
The case study describes dynamic PDA tests conducted on four driven piles in fractured shale where rock penetration ranged from 0.98 to 2.3 m. The pile (HP360x174) was driven with a diesel hammer at a maximum rated energy of 100.47 kN-m. A steel shoe flush with the pile outside dimension was used. The piles reached practical refusal at 50 blows per 25 mm. The CAPWAP and estimated rock penetration established a unit tip bearing resistance of 24.9 MPa and a unit side resistance of 707 kPa. A plugged section was assumed. The unit side resistance is consistent with the recommendation in the AGMU10.2 manual by the Illinois DOT, but the tip resistance observed is almost four times what is recommended in the manual.
{"title":"Case study: H-piles driven into shale rock for compression and uplift resistance","authors":"I. Oweis, S. Anthony","doi":"10.1080/19375247.2018.1521608","DOIUrl":"https://doi.org/10.1080/19375247.2018.1521608","url":null,"abstract":"The case study describes dynamic PDA tests conducted on four driven piles in fractured shale where rock penetration ranged from 0.98 to 2.3 m. The pile (HP360x174) was driven with a diesel hammer at a maximum rated energy of 100.47 kN-m. A steel shoe flush with the pile outside dimension was used. The piles reached practical refusal at 50 blows per 25 mm. The CAPWAP and estimated rock penetration established a unit tip bearing resistance of 24.9 MPa and a unit side resistance of 707 kPa. A plugged section was assumed. The unit side resistance is consistent with the recommendation in the AGMU10.2 manual by the Illinois DOT, but the tip resistance observed is almost four times what is recommended in the manual.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"125 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116048627","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 : 2017-04-06DOI: 10.1080/19375247.2018.1436254
J. Panchal, A. McNamara, S. E. Stallebrass
The availability of space above ground decreases as cities expand, causing a demand for very deep underground structures so developments must mitigate the risk of damaging adjacent buildings. This is especially critical in soft clays where ground movements are considerable and can extend far beyond the excavation site. This paper investigates the efficacy of a shallow lime stabilised clay layer on reducing heave and the settlement profile behind an embedded retaining wall. Centrifuge modelling at 160 g was used to observe surface and subsurface soil movements of a 12 m deep excavation (H) supported by a retaining wall of 8.8 m embedment at prototype scale. Since this research focussed on measures used to minimise heave the model comprised a high stiffness, fully supported ‘rigid wall’ to eliminate ground movements attributed to wall deformation. A direct comparison between a reference test, with no improvements and a test comprising H/2 thick 5% lime stabilised layer indicated that the lime treatment increased the excavation stability by a factor of three.
{"title":"Physical modelling of lime stabilisation in soft soils around deep excavations","authors":"J. Panchal, A. McNamara, S. E. Stallebrass","doi":"10.1080/19375247.2018.1436254","DOIUrl":"https://doi.org/10.1080/19375247.2018.1436254","url":null,"abstract":"The availability of space above ground decreases as cities expand, causing a demand for very deep underground structures so developments must mitigate the risk of damaging adjacent buildings. This is especially critical in soft clays where ground movements are considerable and can extend far beyond the excavation site. This paper investigates the efficacy of a shallow lime stabilised clay layer on reducing heave and the settlement profile behind an embedded retaining wall. Centrifuge modelling at 160 g was used to observe surface and subsurface soil movements of a 12 m deep excavation (H) supported by a retaining wall of 8.8 m embedment at prototype scale. Since this research focussed on measures used to minimise heave the model comprised a high stiffness, fully supported ‘rigid wall’ to eliminate ground movements attributed to wall deformation. A direct comparison between a reference test, with no improvements and a test comprising H/2 thick 5% lime stabilised layer indicated that the lime treatment increased the excavation stability by a factor of three.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121178356","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 : 2017-04-06DOI: 10.1080/19375247.2017.1469323
{"title":"DFI Journal Underwriters","authors":"","doi":"10.1080/19375247.2017.1469323","DOIUrl":"https://doi.org/10.1080/19375247.2017.1469323","url":null,"abstract":"","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"89 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123129848","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 : 2017-04-06DOI: 10.1080/19375247.2018.1470807
J. Ostrowsky
The behaviour of soil–cement and plastic concrete cut-off walls in dams is critically affected by ductility and volumetric stiffness. Post-construction deformation of cut-off walls is common due to the differences in strength and stiffness of the wall and the surrounding embankment material and changes in loading due to changes in the seepage regime. Conventional concrete barriers crack as they deform creating regions of high permeability and concentrated flow in the cracked region. Ductile barriers such as soil–bentonite walls will deform without cracking, but lack structural integrity. The behaviour of intermediate materials, such as soil–cement and plastic concrete, is currently not well understood. A laboratory testing procedure has been developed to quantify the ductility of soil–cement and plastic concrete relative to changes in permeability (hydraulic conductivity) with strain. Tests were performed on a number of soil–cement specimens having varying cement and bentonite contents. The test results show that this method is effective in illustrating and quantifying the differences in behaviour of the soil–cement specimens and effectively measuring low-permeability materials (10−6–10−8 cm s−1). This procedure can be instrumental for defining and quantifying the properties of soil–cement mixtures and plastic concrete used for cut-off wall backfill materials.
大坝中水泥土和塑性混凝土防渗墙的性能受到延性和体积刚度的严重影响。由于墙和周围路堤材料的强度和刚度的差异以及由于渗流状态的变化而引起的荷载变化，防渗墙的施工后变形是常见的。传统的混凝土屏障在变形时产生裂缝，在裂缝区域产生高渗透性和集中流动。韧性屏障，如土-膨润土墙会变形而不开裂，但缺乏结构完整性。中间材料的行为，如水泥土和塑性混凝土，目前还不是很清楚。已经开发了一个实验室测试程序，以量化水泥土和塑性混凝土的延性，相对于渗透性(水力导电性)随应变的变化。试验在一些不同水泥和膨润土含量的水泥土试样上进行。试验结果表明，该方法可以有效地说明和量化水泥土试样的行为差异，并有效地测量低渗透材料(10−6-10−8 cm s−1)。本程序可用于定义和量化用于防渗墙回填材料的水泥土混合物和塑性混凝土的特性。
{"title":"A new approach for evaluating the ductility, volumetric stiffness and permeability of cut-off wall backfill materials","authors":"J. Ostrowsky","doi":"10.1080/19375247.2018.1470807","DOIUrl":"https://doi.org/10.1080/19375247.2018.1470807","url":null,"abstract":"The behaviour of soil–cement and plastic concrete cut-off walls in dams is critically affected by ductility and volumetric stiffness. Post-construction deformation of cut-off walls is common due to the differences in strength and stiffness of the wall and the surrounding embankment material and changes in loading due to changes in the seepage regime. Conventional concrete barriers crack as they deform creating regions of high permeability and concentrated flow in the cracked region. Ductile barriers such as soil–bentonite walls will deform without cracking, but lack structural integrity. The behaviour of intermediate materials, such as soil–cement and plastic concrete, is currently not well understood. A laboratory testing procedure has been developed to quantify the ductility of soil–cement and plastic concrete relative to changes in permeability (hydraulic conductivity) with strain. Tests were performed on a number of soil–cement specimens having varying cement and bentonite contents. The test results show that this method is effective in illustrating and quantifying the differences in behaviour of the soil–cement specimens and effectively measuring low-permeability materials (10−6–10−8 cm s−1). This procedure can be instrumental for defining and quantifying the properties of soil–cement mixtures and plastic concrete used for cut-off wall backfill materials.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130624204","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 : 2017-04-06DOI: 10.1080/19375247.2018.1468522
S. Mobley, K. Costello, G. Mullins
Until recently, concrete flow in tremie-placed drilled shafts has been mischaracterised as rising uniformly with laitance formation occurring at the top of the shaft. In actuality, concrete first fills a portion of the reinforcement cage before flowing radially to the cover region. Depending on slurry type, the radial flow can produce laitance-filled creases/channels that project the reinforcing cage configuration to the side of shaft surface. The flow pattern (and creases) can affect filter cake thickness, cover quality and propensity for corrosion. This paper examines 24 tremie-placed laboratory drilled shaft specimens, constructed using bentonite, polymer or natural slurry to identify correlations between slurry type and laitance channel formation. The extent of the laitance channel effects was quantified with surface texture, corrosion potential and strength distribution methods. A direct correlation between the use of bentonite slurry and laitance channel formation was identified which showed a high propensity for corrosion and lower strengths. Shafts cast using polymer behaved the same as the shafts cast using water, neither of which showed a heightened propensity for corrosion or reduction in strength.
{"title":"The effect of slurry type on drilled shaft cover quality","authors":"S. Mobley, K. Costello, G. Mullins","doi":"10.1080/19375247.2018.1468522","DOIUrl":"https://doi.org/10.1080/19375247.2018.1468522","url":null,"abstract":"Until recently, concrete flow in tremie-placed drilled shafts has been mischaracterised as rising uniformly with laitance formation occurring at the top of the shaft. In actuality, concrete first fills a portion of the reinforcement cage before flowing radially to the cover region. Depending on slurry type, the radial flow can produce laitance-filled creases/channels that project the reinforcing cage configuration to the side of shaft surface. The flow pattern (and creases) can affect filter cake thickness, cover quality and propensity for corrosion. This paper examines 24 tremie-placed laboratory drilled shaft specimens, constructed using bentonite, polymer or natural slurry to identify correlations between slurry type and laitance channel formation. The extent of the laitance channel effects was quantified with surface texture, corrosion potential and strength distribution methods. A direct correlation between the use of bentonite slurry and laitance channel formation was identified which showed a high propensity for corrosion and lower strengths. Shafts cast using polymer behaved the same as the shafts cast using water, neither of which showed a heightened propensity for corrosion or reduction in strength.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134323916","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 : 2017-04-06DOI: 10.1080/19375247.2018.1448552
Hoyoung Seo, Mintae Kim
This study experimentally investigates the effects of the pile diameter and initial soil density on the change of the soil plug state during pile driving through model pile tests. Model piles with two different inner diameters were cut in half vertically and driven along a transparent front wall of a soil tank to visualise the soil plugging process. Loose and dense soils with alternating coloured layers were deposited using fine sand. The entire pile driving process was then recorded using a high-definition digital camera. Detailed image analysis revealed that pipe piles experience repeated transitions from a plugged condition to an unplugged condition during the pile driving process. Compressive strains within the soil plug generally increased with the increasing distance from the top of the soil plug, reached a maximum value and then decreased toward the pile base. Furthermore, the density of the soil plug increased from its initial value and reached a terminal value as the pile penetration increased.
{"title":"Soil plug behaviour of open-ended pipe piles during installation","authors":"Hoyoung Seo, Mintae Kim","doi":"10.1080/19375247.2018.1448552","DOIUrl":"https://doi.org/10.1080/19375247.2018.1448552","url":null,"abstract":"This study experimentally investigates the effects of the pile diameter and initial soil density on the change of the soil plug state during pile driving through model pile tests. Model piles with two different inner diameters were cut in half vertically and driven along a transparent front wall of a soil tank to visualise the soil plugging process. Loose and dense soils with alternating coloured layers were deposited using fine sand. The entire pile driving process was then recorded using a high-definition digital camera. Detailed image analysis revealed that pipe piles experience repeated transitions from a plugged condition to an unplugged condition during the pile driving process. Compressive strains within the soil plug generally increased with the increasing distance from the top of the soil plug, reached a maximum value and then decreased toward the pile base. Furthermore, the density of the soil plug increased from its initial value and reached a terminal value as the pile penetration increased.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133457958","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 : 2017-04-06DOI: 10.1080/19375247.2018.1436382
A. Khosravifar, J. Nasr
Effective-stress nonlinear dynamic analyses (NDA) were performed for piles in the liquefiable sloped ground to assess how inertia and liquefaction-induced lateral spreading combine in long- and short-duration motions. A parametric study was performed using input motions from subduction and crustal earthquakes covering a wide range of durations and amplitudes. The NDA results showed that the pile demands increased due to (a) longer duration shakings, and (b) liquefaction-induced lateral spreading compared to nonliquefied conditions. The NDA results were used to evaluate the accuracy of the equivalent static analysis (ESA) recommended by Caltrans/ODOT for estimating pile demands. Finally, the NDA results were used to develop new ESA methods to combine inertial and lateral spreading loads for estimating elastic and inelastic pile demands.
{"title":"Modified design procedures for bridge pile foundations subjected to liquefaction-induced lateral spreading","authors":"A. Khosravifar, J. Nasr","doi":"10.1080/19375247.2018.1436382","DOIUrl":"https://doi.org/10.1080/19375247.2018.1436382","url":null,"abstract":"Effective-stress nonlinear dynamic analyses (NDA) were performed for piles in the liquefiable sloped ground to assess how inertia and liquefaction-induced lateral spreading combine in long- and short-duration motions. A parametric study was performed using input motions from subduction and crustal earthquakes covering a wide range of durations and amplitudes. The NDA results showed that the pile demands increased due to (a) longer duration shakings, and (b) liquefaction-induced lateral spreading compared to nonliquefied conditions. The NDA results were used to evaluate the accuracy of the equivalent static analysis (ESA) recommended by Caltrans/ODOT for estimating pile demands. Finally, the NDA results were used to develop new ESA methods to combine inertial and lateral spreading loads for estimating elastic and inelastic pile demands.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116496918","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 : 2017-04-06DOI: 10.1080/19375247.2018.1468595
A. Lemnitzer, T. Siegel
We are pleased to publish this special award issue featuring a set of outstanding manuscripts submitted to the DFI 2017 Young Professor and Student Paper competitions. Since 1985, DFI and the DFI Educational Trust have held an annual Young Professor Paper Competition as a means to help bridge the gap between practice and study. This year the range of submission covered a broad technical spectrum, ranging from numerical modeling to large scale experimental testing of axially and laterally loaded pile foundations, statistical analyses and uncertainty predictions using big data analysis methodologies, state-of-the-art evaluation of regional, national and international design recommendations, laboratory and model scale studies on soil behavior, ground improvement and installation effects during foundation construction, as well as QA/QC analysis pertaining to drilled shaft installation and long term shaft integrity. The winning papers as well as a set of manuscripts that received a special recognition are published in this issue. The editors would like to thank the competition reviewers for their constructive feedback to all manuscripts and the substantial amount of time spent on more than 15 paper submissions. We are so grateful for the successful competition and sincerely appreciate your service to DFI and your encouragement of our rising and promising young professionals. Mobley and Costello, a graduate student co-author team from the University of South Florida won the 2017 student paper competition for their research work on “The Effect of Slurry Type on Drilled Shaft Cover Quality”. Sarah Mobley and Kelly Costello, both PhD candidates in the Civil and Environmental Engineering Department at USF, study and research under the supervision of Prof. Gray Mullins. The research team examined 24 tremie-placed laboratory drilled shaft specimens, constructed using bentonite, polymer or natural slurry to identify correlations between slurry type and laitance channel formation. The authors received their award during DFI’s annual conference in NewOrleans and delivered a stellar presentation during the conference’s technical sessions. Mobley and Costello’s work is a critical contribution to increasing the long term resilience of drilled shaft foundations by identifying and quantifying the effects of shaft surface degradation triggered by the use of different slurry types. Closely followed, with extremely high review scores are two runner-up researchers in the student paper category: Van Wijngaarden received a runner-up award for his work on the “Modelling of Pore Pressure Developments below Cyclically Loaded Offshore Gravity Foundations”, a study that investigates the effects pore pressure increase and dissipation on the stability of the foundation system. Martijn van Wijngaarden recently graduated from the Delft University of Technology in the Netherlands and currently works at Volker Staal en Funderingen in Rotterdam. In his paper, he outlines an approach
我们很高兴地出版这一特别奖项，其中包括一套提交给DFI 2017年青年教授和学生论文比赛的优秀手稿。自1985年以来，DFI和DFI教育信托基金每年都会举办青年教授论文比赛，以帮助弥合实践与学习之间的差距。今年的提交范围涵盖了广泛的技术范围，从数值模拟到轴向和横向荷载桩基的大规模实验测试，使用大数据分析方法的统计分析和不确定性预测，最先进的区域，国家和国际设计建议评估，土壤行为的实验室和模型尺度研究，地基改善和基础施工期间的安装效果，以及与钻井安装和井筒长期完整性相关的QA/QC分析。获奖论文及一套获得特别认可的手稿将在本期刊登。编辑们要感谢比赛评审员对所有稿件的建设性反馈，以及在超过15篇论文提交上花费的大量时间。我们非常感谢这次比赛的成功举办，并衷心感谢您为DFI提供的服务，以及您对我们正在成长和有前途的年轻专业人士的鼓励。来自南佛罗里达大学的研究生合作团队Mobley和Costello以“泥浆类型对钻井井盖质量的影响”的研究成果赢得了2017年学生论文竞赛。Sarah Mobley和Kelly Costello都是USF土木与环境工程系的博士候选人，在Gray Mullins教授的指导下学习和研究。研究小组检查了24个实验井样本，这些样本使用膨润土、聚合物或天然泥浆构建，以确定泥浆类型与沉积物通道形成之间的相关性。两位作者在纽沃尔什举行的DFI年度会议上获得了奖项，并在会议的技术会议上发表了精彩的演讲。Mobley和Costello的工作通过识别和量化使用不同类型泥浆引发的井筒表面退化的影响，对提高钻井井筒基础的长期弹性做出了重要贡献。紧随其后的是两名获得极高评价分数的学生论文类亚军:Van Wijngaarden因其关于“循环加载海上重力基础下孔隙压力发展的建模”的研究获得亚军，该研究调查了孔隙压力增加和消散对基础系统稳定性的影响。Martijn van Wijngaarden最近从荷兰代尔夫特理工大学毕业，目前在鹿特丹的Volker Staal en Funderingen工作。在他的论文中，他概述了一种方法，通过建立由于风、波浪和涡轮机操作以及加载的动态放大而产生的载荷谱，来评估海洋基础下随时间变化的孔隙压力发展。Van Wijngaarden得出结论，由于循环荷载的不规则性导致最大压力在基础以下的显著扩散，因此只能通过大量生成的时间序列来实现对超孔隙压力的可靠预测。Ostrowsky的论文《一种评估防渗墙回填材料延性、体积刚度和渗透性的新方法》获得了二等奖。Jennifer Ostrowsky是犹他州立大学的一名博士生，她的研究生导师John Rice教授在一起工作。研究小组开发了一种实验室测试程序，以量化土壤和塑性混凝土的延性，相对于渗透率(水力导电性)随应变的变化。该小组对不同水泥和膨润土含量的水泥土样本进行了广泛的测试。测试结果表明，该方法可以有效地说明和量化2017年DFI董事会的差异
{"title":"Editorial Note – Issue 2-3 (2017) – Award Issue","authors":"A. Lemnitzer, T. Siegel","doi":"10.1080/19375247.2018.1468595","DOIUrl":"https://doi.org/10.1080/19375247.2018.1468595","url":null,"abstract":"We are pleased to publish this special award issue featuring a set of outstanding manuscripts submitted to the DFI 2017 Young Professor and Student Paper competitions. Since 1985, DFI and the DFI Educational Trust have held an annual Young Professor Paper Competition as a means to help bridge the gap between practice and study. This year the range of submission covered a broad technical spectrum, ranging from numerical modeling to large scale experimental testing of axially and laterally loaded pile foundations, statistical analyses and uncertainty predictions using big data analysis methodologies, state-of-the-art evaluation of regional, national and international design recommendations, laboratory and model scale studies on soil behavior, ground improvement and installation effects during foundation construction, as well as QA/QC analysis pertaining to drilled shaft installation and long term shaft integrity. The winning papers as well as a set of manuscripts that received a special recognition are published in this issue. The editors would like to thank the competition reviewers for their constructive feedback to all manuscripts and the substantial amount of time spent on more than 15 paper submissions. We are so grateful for the successful competition and sincerely appreciate your service to DFI and your encouragement of our rising and promising young professionals. Mobley and Costello, a graduate student co-author team from the University of South Florida won the 2017 student paper competition for their research work on “The Effect of Slurry Type on Drilled Shaft Cover Quality”. Sarah Mobley and Kelly Costello, both PhD candidates in the Civil and Environmental Engineering Department at USF, study and research under the supervision of Prof. Gray Mullins. The research team examined 24 tremie-placed laboratory drilled shaft specimens, constructed using bentonite, polymer or natural slurry to identify correlations between slurry type and laitance channel formation. The authors received their award during DFI’s annual conference in NewOrleans and delivered a stellar presentation during the conference’s technical sessions. Mobley and Costello’s work is a critical contribution to increasing the long term resilience of drilled shaft foundations by identifying and quantifying the effects of shaft surface degradation triggered by the use of different slurry types. Closely followed, with extremely high review scores are two runner-up researchers in the student paper category: Van Wijngaarden received a runner-up award for his work on the “Modelling of Pore Pressure Developments below Cyclically Loaded Offshore Gravity Foundations”, a study that investigates the effects pore pressure increase and dissipation on the stability of the foundation system. Martijn van Wijngaarden recently graduated from the Delft University of Technology in the Netherlands and currently works at Volker Staal en Funderingen in Rotterdam. In his paper, he outlines an approach ","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131234718","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 : 2017-04-06DOI: 10.1080/19375247.2018.1467070
Martijn van Wijngaarden
Saturated sands show an increase in pore pressure under cyclic loading in undrained conditions. A challenge in modelling pore pressures below offshore gravity foundations is the effect of random or irregular cyclic loads. In literature, a method is proposed in which equivalent loads with a constant period and a constant amplitude are used. In this paper, a method is presented which takes both the irregular nature of cyclic loads and the real load development in time into account. The cyclic loads are derived in the frequency domain for a gravity foundation of an offshore wind turbine. The irregular loads are simulated with a random phase model. The pore pressures are modelled in a one-dimensional model including three-dimensional dissipation. The results show that the irregular nature of the cyclic loads results in a significant spread in maximum pore pressures below the foundation.
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