DFI Journal - The Journal of the Deep Foundations Institute最新文献

{"title":"Response of a drilled shaft foundation constructed in a redrilled shaft excavation following collapse","authors":"M. Race, R. Coffman","doi":"10.1179/1937525515Y.0000000003","DOIUrl":"https://doi.org/10.1179/1937525515Y.0000000003","url":null,"abstract":"Two drilled shaft foundations (DSFs) of equal size (1.2 m diameter) were installed at the Turrell Arkansas Test Site (TATS). The soil stratigraphy at the TATS consisted of 6.1 m of clay underlain by 3.0 m of silt underlain by sand. After drilling the excavation for the North 1.2 m DSF, the silty soil collapsed from the sidewall of the excavation into the bottom of the excavation. Following the collapse, the excavation was redrilled and the construction of the DSF was completed. The measured capacity, unit side resistance, and end bearing resistance of the South 1.2 m diameter DSF were predicted by using software programs and mean values of soil data. The measured response of the North 1.2 m diameter DSF was backward modeled to determine the appropriate strength and stress reduction. Based on the measured data for this site, a 10 percent reduction in unit weight within the silt layer and a modification of the soil properties within the top 3.0 m of the sand layer produced predicted responses that matched the measured responses.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128080425","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}

{"title":"Industry survey of state of practice for helical piles and tiebacks","authors":"S. Clemence, A. Lutenegger","doi":"10.1179/1937525514Y.0000000007","DOIUrl":"https://doi.org/10.1179/1937525514Y.0000000007","url":null,"abstract":"Abstract The last 25 years have seen exponential growth in the use of helical piles and tiebacks. Helical piles and tiebacks are now considered a standard of practice in the deep foundation industry. With the dramatic growth of this technology and the proliferation of available technical information, a synthesis paper on the current state of the practice was considered a valuable addition to the literature as a way to quantify and summarize the current state-of-practice. Based on the increased interest and global applications of helical foundations, in 2013 the Helical Piles and Tiebacks Committee (HPTC) commissioned a state-of-practice survey of current practices in the use, design and installation of helical piles and tiebacks. The major goals of the survey were to understand the current status of applications of helical piles and tiebacks, their design and construction, quantify perceived needs and to identify future trends. The results for the present survey are very encouraging and have clearly demonstrated that there is a cadre of engineers and manufacturers dedicated to continued improvement and understanding of helical foundation systems. Continued work and education of design engineers, architects, government agencies and owners will ensure continued success and progress.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115917831","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}

{"title":"Load tests on drilled shaft foundations in moderately strong to strong limestone","authors":"M. Race, R. Coffman","doi":"10.1179/1937525514Y.0000000004","DOIUrl":"https://doi.org/10.1179/1937525514Y.0000000004","url":null,"abstract":"Abstract Three drilled shaft foundations (DSFs) were constructed in moderately strong to strong limestone at the Siloam Springs Arkansas Test Site (SSATS). The embedment lengths within the limestone were 3·0, 1·5 and 2·1 m for the DSFs with diameters of 1·2, 1·8 and 1·2 m, respectively. The DSFs were instrumented to facilitate cross-hole sonic logging testing and full scale load testing using bidirectional load cells (BLCs). Lessons learned from construction included the: (1) proper concrete pouring techniques; (2) ability to retrofit improperly installed telltale instrumentation; and (3) influence of rock socket length within moderately strong to strong limestone. Recommended design, construction and testing techniques in moderately strong to strong limestone are presented. Based on the full scale testing, t–z model recommendations for weathered limestone and moderately strong to strong limestone are presented and discussed. Comparisons between measured unit side resistance and current design recommendations are also considered.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134009407","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}

{"title":"New device for measuring drilled shaft bottom sediment thickness","authors":"J. Ding, K. A. McIntosh, R. M. Simon","doi":"10.1179/1937525515Y.0000000004","DOIUrl":"https://doi.org/10.1179/1937525515Y.0000000004","url":null,"abstract":"Abstract The sediment thickness at the bottom of a drilled shaft before the placement of concrete plays a significant role in the development of drilled shaft bearing capacity and settlement, especially for an end-bearing shaft where side shear resistance is limited and only end-bearing resistance is considered significant. Load tests have demonstrated that conscientious bottom cleaning is necessary to achieve suitable load transfer in end-bearing. Inspection and measurement of the bottom sediment thickness before concreting is challenging, expensive, and often time consuming for contractors and inspectors when direct visual inspection is not possible, as for shafts drilled through slurry or water. The Ding inspection device (DID) was developed by John Z. Ding for measuring the sediment thickness at the bottom of a drilled shaft without human access into the excavation. Laboratory model tests and field comparisons to the miniature shaft inspection device (mini-SID) have demonstrated repeatability and accuracy of sediment thickness measurements using the device.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114033042","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}

{"title":"Static tests on instrumented piles affected by residual load","authors":"B. Fellenius","doi":"10.1179/1937525515Y.0000000001","DOIUrl":"https://doi.org/10.1179/1937525515Y.0000000001","url":null,"abstract":"Abstract Analysis of results from a static loading tests on an instrumented pile usually assumes that the gage determined loads represent the true loads in the test pile. However, more often than not, residual load will have been present in the pile at the start of the static test. Disregarding these in the analysis will misrepresent the load–movement response and the loads determined from the strain–gage instrumentation, as presented in the paper. The results of three static loading tests: a 400 mm diameter, 45 m long, concrete filled, closed toe, steel pipe pile driven in soft clay, a 460 mm diameter, 22 m long bored pile (screw pile) in silt and sand and stiff clay, and a 600 mm diameter, 15 m long, jacked-in concrete pile in a residual, dense, silty sandy weathered sandstone. The measured load distributions are corrected for residual load, demonstrating the interdependence of the distributions of “False” and “True” distributions of load.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130065613","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}

{"title":"Performance of biocemented Sydney sand using ex situ mixing technique","authors":"Y. Duraisamy, D. Airey","doi":"10.1179/1937525515Y.0000000002","DOIUrl":"https://doi.org/10.1179/1937525515Y.0000000002","url":null,"abstract":"Abstract This paper describes a small-scale demonstration of an ex situ mixing technique that uses biocementation as an alternative to existing ground improvement techniques. The main objective of this research is to improve the strength and the stiffness of loose sand. Biocemented sand specimens have been produced by mixing a urease producing bacteria with nutrients and Sydney sand. Triaxial test with bender elements and the physical model test are conducted to investigate calcium carbonate precipitation and the properties of the soil. The model foundation tests have been performed at 1 g in a cylindrical tank with diameter of 600 mm. The tank has been filled with loose Sydney sand and a cemented column of 38 mm in diameter has been created in the center of the tank. A footing of 90 mm diameter has been placed on the sand surface and loaded to large displacements. The ability of the biocemented column made by ex situ mixing to significantly improve the foundation response is well demonstrated. Triaxial test performed on biocemented specimens also showed significant strength and stiffness increase over uncemented specimens. These tests confirmed the feasibility of using ex situ mixing technique to induce biocementation and provide valuable insight into the factors that must be considered in developing field applications.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121212027","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}

{"title":"New technologies and applications: materials and equipment in near surface geothermal systems","authors":"R. Katzenbach, C. Olgun, F. Loveridge, M. Sutman, G. A. Bowers, J. McCartney, L. Laloui, T. Mimouni, F. Dupray, J. Spitler, F. Clauss, L. L. Meyer, G. Akrouch","doi":"10.1179/1937525514Y.0000000012","DOIUrl":"https://doi.org/10.1179/1937525514Y.0000000012","url":null,"abstract":"Abstract This paper presents an overview of new technologies and applications on thermoactive geostructures. A discussion session on issues involved with near surface geothermal systems is presented, focusing on opportunities for developing new technologies to address these issues. In addition, opportunities for new applications of geothermal heat exchange in geotechnical engineering were discussed. Progress on the development of new materials and equipment that may be used to enhance the rate of heat transfer or heat storage capacity was discussed.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121197073","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}

{"title":"Environmental impact calculations, life cycle cost analysis","authors":"D. Nicholson, P. Smith, G. A. Bowers, F. Cuceoglu, C. Olgun, J. McCartney, K. Henry, L. L. Meyer, F. Loveridge","doi":"10.1179/1937525514Y.0000000009","DOIUrl":"https://doi.org/10.1179/1937525514Y.0000000009","url":null,"abstract":"Abstract This session explored the evaluation and characterization of the sustainability of thermoactive geotechnical systems. Thermoactive geotechnical systems take advantage of shallow geothermal energy by using the foundation of a structure as a heat source and sink for use with a ground source heat pump. Methods for their evaluation within a sustainability framework still need to be developed. This can be done within larger regulatory frameworks such as the Code for Sustainable Homes. The Life Cycle Analysis methodology has been used to examine non-thermoactive geotechnical systems using both embodied carbon and embodied energy as metrics. Life Cycle Analyses have also been performed on ground source heat pumps and can provide valuable insight into the indirect operational environmental impacts of thermoactive geotechnical systems.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128500627","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}

{"title":"Outcomes from international workshop on thermoactive geotechnical systems for near-surface geothermal energy: from research to practice","authors":"C. Olgun, J. McCartney","doi":"10.1179/1937525514Y.0000000005","DOIUrl":"https://doi.org/10.1179/1937525514Y.0000000005","url":null,"abstract":"Abstract This paper summarizes the main outcomes of an NSF sponsored workshop focused on thermoactive geotechnical systems for near surface geothermal energy. A group of 55 researchers from around the world gathered in March 2013 for a 3 day workshop in Lausanne, Switzerland to discuss the current status of the linkages between geotechnical engineering and near surface geothermal energy. This paper provides a summary of the state of the art in characterization of materials in thermally active geotechnical systems, as well as our understanding of the thermal and thermomechanical behavior of these systems. The paper also includes a review of available thermal and thermomechanical design methods, along with associated lessons learned from implementation of thermally active systems. A discussion of the emerging technologies at the interface between geotechnical engineering and near surface geothermal energy indicates that there are many opportunities to transfer knowledge between different fields. A list of current challenges and the associated research agenda for the future identified during the workshop indicates that many important challenges have been overcome but there are still important issues that need to be solved.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124975388","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}

{"title":"Editors’ Note","authors":"Guney Olgun","doi":"10.1179/1937524714z.00000000017","DOIUrl":"https://doi.org/10.1179/1937524714z.00000000017","url":null,"abstract":"This special issue is dedicated to the state of practice of geothermal foundations, with a particular focus on energy pile foundations. The selection and organization of the seven papers were performed in collaboration with Guney Olgun, Ph.D. (Virginia Tech) and John McCartney, Ph.D. (University of CA, San Diego) with whom we would like to credit the technical leads of the manuscripts. The authors represent a truly international effort from the private sector, academic institutions and governmental agencies of seven different countries on three different continents, namely, the USA, France, Switzerland, Germany, UK, Portugal and Australia. In March 2013, a group of 58 leading researchers from around the world gathered for a special NSF sponsored 3day workshop in Lausanne, Switzerland, to discuss the current status of the relationship between geotechnical engineering and near surface geothermal energy. This issue summarizes the most recent research findings and developments in the field of geothermal pile foundations as presented during the workshop and supplemented by the author’s most recent individual research studies. Beyond highlighting the state of practice in construction and installation and the state-of-the-art in design and development, each paper identifies important areas of improvement, as well as, future research. An overview paper by Olgun and McCartney describes the general principles of thermo active geotechnical systems; Amis et al. discuss the best practice in installation, field testing and laboratory investigations along with the benefits of early project collaboration related to the construction of geothermal systems using specific examples drawn from current practice in the UK. Olgun et al. provide a presentation of the existing guidelines and their implementation in building codes and the need for a uniform design procedure that is sufficiently supported through research data. The discussion also includes incentives for the further advancement of green energy with a particular focus on programs such as BREEAM (the UK) and LEED (the USA). Katzenbach et al. focus on new technologies and materials in near surface geothermal systems, presenting several experimental case studies with accompanying analytical modeling. Laloui et al. study the impact of thermohydromechanical behavior of soils on thermoactive geotechnical systems, and how it affects the performance of thermoactive geotechnical system. Bourne-Webb et al. take a critical look at the analytical capabilities to predict thermal stress and strain response and provide valuable recommendations on how to overcome shortcomings of the existing methods in accurately simulating cyclic heating and cooling effects, transient pore water pressure generation and dissipation, and the effects of radial stress changes. Finally, Nicholson et al. provide a perspective on the sustainability of geothermal systems, discussing the environmental impact and regulations and a life cycle analysis","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127184552","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}