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

{"title":"Performance-based Design of Energy Pile Foundations","authors":"A. F. Rotta Loria","doi":"10.1080/19375247.2018.1562600","DOIUrl":"https://doi.org/10.1080/19375247.2018.1562600","url":null,"abstract":"Over the past twenty years, an increasing amount of research has been performed to understand the multiphysical behaviour and to address the geotechnical and structural design of so-called energy piles, i.e. deep foundations that can serve any superstructure as both structural supports and geothermal heat exchangers. The coupled application of thermal and mechanical loads to energy piles, due to their multifunctional operation, represents a challenge. Currently, knowledge about the response of energy piles subjected to thermal and mechanical loads is accessible, along with some design guidance. However, this knowledge is fragmented and no recognised performance-based design framework is available. Looking at such challenge, this paper presents a theoretical and experimental analysis of the multiphysical behaviour of energy piles, as well as a performance-based design framework for such foundations. The work highlights that thermal loads involve effects that can be neglected in the design of energy piles at ultimate limit states and can be considered relevant only at serviceability limit states. Based on this result, the performance-based design of energy piles at ultimate limit states reduces to a conventional pile design process while the design at serviceability limit states must account for a number of proposed provisions and verifications.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"60 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129531765","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":"DFI Journal Underwriters","authors":"","doi":"10.1080/19375247.2018.1547351","DOIUrl":"https://doi.org/10.1080/19375247.2018.1547351","url":null,"abstract":"","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133721212","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":"Comparison of FEA and analytical methods for determining stability of a RAP supported MSE wall","authors":"Emily C. Reed, D. VandenBerge","doi":"10.1080/19375247.2018.1562593","DOIUrl":"https://doi.org/10.1080/19375247.2018.1562593","url":null,"abstract":"Global stability is one of the failure modes that must be analysed for retaining walls. Limit equilibrium analysis of walls using slope stability software tends to result in a factor of safety that is either too high (circular surfaces) or too low (V-shaped non-circular surfaces). Finite element analysis (FEA) of walls provides a better solution but can be time-intensive and expensive. The primary aim of this project is to compare the results of FEA models with a simpler analytical bearing capacity method that uses Meyerhof’s load inclination correction factors. In particular, cases were examined where Rammed Aggregate Pier reinforcing elements (RAPs) support a mechanically stabilised earth (MSE) retaining wall. For this project, several FEA models replicating these cases were created. Geometric parameters included the area ratio of RAP to matrix soil, or “replacement ratio”, and the dimensions of the MSE wall. Each geometric configuration was then iterated over a range of undrained strength for the matrix soil, resulting in a different factor of safety for each model. A spreadsheet was also created containing the necessary calculations for the Meyerhof bearing capacity method. The factor of safety from the Meyerhof method was compared to the factor of safety computed for each corresponding FEA model. The results show an excellent relationship between the computed factors of safety for FEA models and the bearing capacity method, especially for factors of safety ranging from 1 to 1.5. At factors of safety above about 1.5, the critical failure mode becomes sliding rather than global stability, and the two methods diverge. The major implications of this research are that a complex FEA model can potentially be replaced by the simpler analytical Meyerhof bearing capacity method. Wall designers will benefit from a quick check on the global stability of a retaining wall without having to spend the time and money on more expensive FEA modelling.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130166071","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":"Texas cone penetrometer foundation design method: Qualitative and quantitative assessment","authors":"R. Moghaddam, P. Jayawickrama, W. Lawson, J. Surles, Hoyoung Seo","doi":"10.1080/19375247.2018.1536409","DOIUrl":"https://doi.org/10.1080/19375247.2018.1536409","url":null,"abstract":"This paper presents a qualitative and quantitative evaluation of the predictive validity of the Texas Cone Penetration (TCP) foundation design method. Allowable loads were determined using both strength-based and serviceability-based models and were further compared to predicted allowable loads using the TCP foundation design charts. The predictive validity of the TCP method was evaluated using a final dataset consisting of 60 full-scale load tests comprising 33 driven piles and 27 drilled shafts, all founded in soil materials. The qualitative evaluation consisted of a visual assessment of the scatterplot compared to the equal prediction line. In the case of the quantitative assessment, regression models were fitted to the dataset, and the accuracy and precision of the models were evaluated based on statistical analyses. Results show that the predictive validity of the TCP-based foundation design method is accurate with low precision. The qualitative evaluation of the strength-based data showed slight data scatter around the equal prediction line. In the case of the serviceability-based model, data points indicated the same slight scatter with major concentration above the equal prediction line in the conservative prediction region. With a p-value <.05, results from the quantitative analyses showed a statistically significant relationship between the proposed models and the allowable loads predicted using the TCP. The R-square value for the models was between 0.776 and 0.814.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117153956","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":"DFI Journal Underwriters","authors":"","doi":"10.1080/19375247.2018.1547350","DOIUrl":"https://doi.org/10.1080/19375247.2018.1547350","url":null,"abstract":"","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"103 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":"124691367","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":"Scale model investigation of the effect of vertical load on the lateral response of micropiles in sand","authors":"K. Kershaw, R. Luna","doi":"10.1080/19375247.2018.1462040","DOIUrl":"https://doi.org/10.1080/19375247.2018.1462040","url":null,"abstract":"Research regarding the effect of simultaneous axial and lateral (combined) loading on micropile foundations is limited and somewhat conflicting. This paper presents the results of a scale model study completed to assess the impact of an axial (vertical) load on the lateral response of micropiles in sand. A laboratory test pit was filled with fine sand, and the density of the sand was varied from loose to dense. A total of 17 model micropiles were instrumented, installed and tested. This paper presents details regarding testing materials, test design, soil conditions, instrumentation, installation, experimental program, testing results and comparison of testing results to p-y analyses. The results of the study indicated that the lateral deflection was only significantly affected by the introduction of a constant axial load for large lateral loads. However, bending moments in the micropiles were significantly increased for combined load conditions at all magnitudes of lateral load.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"201 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":"133761048","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":"Classification of piles based on the results of low strain pile integrity tests – Case studies of selected piles in Lagos and Port-Harcourt, Nigeria","authors":"Ademola Bolarinwa, R. Kalatehjari, Adewale Daniel Ogunwole","doi":"10.1080/19375247.2017.1422336","DOIUrl":"https://doi.org/10.1080/19375247.2017.1422336","url":null,"abstract":"This paper presents the performance of low strain pile integrity test (LSPIT) based on data collected from selected piles in Lagos and Port-Harcourt industrial cities of Nigeria. Two types of piles were considered in this paper, namely bored piles (BP) and auger cast-in-place piles (ACIP). A brief review of LSPIT was carried out and the case studies were introduced. Wireless pile integrity tester (PIT-W) manufactured by Pile Dynamics Incorporation was applied for data collection and analysis. Basically, seven major categories of LSPIT can be introduced based on velocity curves reflection. These categories of piles are well detailed in the result section as AA, AB, ABx, PFx, PDx, IVx and IR. The classification above improves existing ones because information is available on precise pile length at which, soundness and defects of pile can be detected. Results obtained from case studies indicated that tested piles were primarily of the AA, AB, PFx and PDx categories/type. The study areas were chosen because most of the industrial application of piles in Nigeria can be found in these two cities. Summarily, all tested BP were structurally sound, about 78% of the all tested piles (BPs and ACIPs) were reported to be structurally sound, while 22% have impedance changes indicating slight soil intrusion, negligible voids within concrete mass without severe effect on the structural soundness of piles and they were typically ACIPs. The term ‘anomaly’ in this paper is used to describe piles with slight positive reflection for small necking, voids, cracks, etc.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"24 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":"134128760","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 laterally loaded helical piles in clayey soils established from field experience","authors":"M. Sakr","doi":"10.1080/19375247.2018.1430481","DOIUrl":"https://doi.org/10.1080/19375247.2018.1430481","url":null,"abstract":"Despite the wide use of helical piles with large diameters, the available studies documenting their lateral performance are few. To date, helical piles with shaft diameters up to 1200 mm have been successfully used in Alberta, Canada. The results of a lateral pile load test programs and the field monitoring of helical and driven piles with shaft diameters varied between 219 and 508 mm, installed in firm to very soft clay to very hard clay till were presented in this study. Load testing programs were carried out at five different sites. Effect of pile installation on the lateral capacities of helical piles was also evaluated. Direct comparison between lateral resistances of helical and driven piles was performed. The results of the load tests were compared to a p–y curve model using LPILE 2016 (LPILE. 2016. A program for the analysis of piles and drilled shafts under lateral loads. Austin, TX: Ensoft Inc.). Based on the results of this study it was found that helical piles can develop considerable resistance to lateral loads and their lateral resistances are almost exclusively controlled by the shaft size.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"4 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":"132432078","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":"Binder threshold approach to predicting soil mixing strength in organic soils","authors":"K. Costello, S. Baker, G. Mullins","doi":"10.1080/19375247.2018.1502066","DOIUrl":"https://doi.org/10.1080/19375247.2018.1502066","url":null,"abstract":"Organic soil stabilisation by mixing with cementitious binders, called soil mixing, has traditionally been problematic due to unpredictable strength gains. Anecdotally, practitioners and specialty contractors recognise a notable increase in the required amounts of binder relative to inorganic soil mixing experiences but this too has been unpredictable. This paper discusses the results from laboratory and field case studies conducted to better estimate the amount of binder required for organic soil mixing, which makes design strength predictions possible.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"7 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":"133341681","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":"Editorial Note – Issue 1 (2018)","authors":"A. Lemnitzer, T. Siegel","doi":"10.1080/19375247.2018.1546936","DOIUrl":"https://doi.org/10.1080/19375247.2018.1546936","url":null,"abstract":"We are thrilled to present another DFI Journal issue with a variety of research and case studies on deep foundation design, construction, and testing. Kershaw and Luna open the issue with a model scale investigation of the effect of vertical loading on the response of micropiles in sand. The authors tested 17 instrumented model micropiles in a laboratory setting to study the effect of combined axial and lateral loading on the nonlinear soil-structure interaction response of the foundation system. Particularly for loose sands and for piles with lack of head restraint, Kershaw and Luna observed a more pronounced and sudden failure under combined loading compared to observations for laterally-only loaded micropiles. Another micropile application is presented by authors Nodine, Eggers, Walker and Aubrecht, who describe a clever solution for difficult below-groundwater soil conditions at a site in Buffalo, New York. This case study explains the revitalisation of the former Buffalo Memorial Audtorium site, which was constructed in 1940 and founded on H-piles. Micropiles were used to support the new building and provide additional capacity for the four-story construction to be erected. Primary challenges and solutions described in the study include the drilling through the existing slab, the development of a water proofing system, construction obstructions encountered during the drilling and construction process, as well as challenges posed by the asymmetric foundation geometries. The performance of helical pile foundations under lateral loading is documented by Sakr who experimentally investigated the nonlinear response behaviour of helical and driven piles on five different sites in Alberta, Canada. Direct comparisons between the load-displacement behaviour as well as comparisons with commercially available foundation design software showed that lateral resistances for piles with similar geometries were close to each other despite the different installation methods. Soil disturbance was found to play a bigger role at large pile displacement levels, and especially when the predrilling process used auger equipment that matched the diameter of the anticipated helical pile. Recommendations with respect to the installation and construction based on the observed load test results are offered by the author. Another load test case history is presented by Oweis and Erdman, who describe a series of dynamic pile load testing on H-Piles driven into fractured shale rock. The CAPWAPmethodology was utilised to analyse the pile driving performance and determination of resistance to axial loading. The authors observed side resistances in good agreement with published recommendations by the local State Department but achieved average tip resistances approximately four times higher than predictions by design provisions. A local case study at the Lagos and PortHarcourt industrial cities of Nigeria is presented by Bolarinwa, Kalatehjari and Ogunwole. The authors conducted","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"2 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":"131649128","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}