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

{"title":"Piezocone Penetration Testing in Florida High Pile Rebound Soils","authors":"Fauzi H. Jarushi, P. Cosentino, E. H. Kalajian","doi":"10.1179/dfi.2013.7.2.003","DOIUrl":"https://doi.org/10.1179/dfi.2013.7.2.003","url":null,"abstract":"Abstract Contractors and engineers have experienced pile installation problems while driving high displacement piles with single-acting diesel hammers at Florida Department of Transportation (FDOT) construction sites located throughout the Central and Panhandle regions of Florida. At certain depths during pile driving in saturated soils, rebound exceeding 1 inch (25 mm) was experienced, followed by a small permanent-set during each hammer blow. High pile rebound (HPR) may cause false refusal to occur, stopping the pile driving and resulting in a limited pile capacity. In some cases, rebound leads to pile damage, delaying of the construction project and foundation redesign. In this paper, the response of HPR is investigated using cone penetrometer testing (CPT) and a pile driving analyzer (PDA). PDA data, which yielded the amount and the depth where rebound occurred, produced the pile movement per blow, Nineteen Piezocone soundings were performed at seven FDOT sites in Florida, of which five sites experienced a rebound greater than 0.6 inches (15 mm), one site yielded rebound of 0.35 inches (9 mm), and one site’s rebound was less than the FDOT limit of 0.25 inches (6 mm). In order to improve the knowledge about the soil types producing HPR, a traditional geotechnical investigation on grain-size distribution and soil plasticity allowing for classification using Unified Soil Classification System (USCS) was conducted. Piezocone data were interpreted using the CPT and CPTu soil behavior type (SBT) charts proposed by Schmertmann (1978), Robertson (1990) (i.e., Q-Fr, Q-Rf, and Q-Bq), Eslami and Fellenius (2004), and Schneider et al. (2008). Comparison with classification data from laboratory tests was in excellent agreement with the CPT soil type, indicating that the CPT is a useful tool in evaluation of HPR or “large quake” soils. Correlations between rebound and CPTu data were developed showing that rebound is a direct function of both friction ratio Rf and pore pressure u2.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127846058","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":"A Review of the Design Formulations for Static Axial Response of Deep Foundations from CPT Data (DFI 2013 Student Paper Competition Runner-Up)","authors":"F. Niazi, P. Mayne","doi":"10.1179/dfi.2013.7.2.005","DOIUrl":"https://doi.org/10.1179/dfi.2013.7.2.005","url":null,"abstract":"Abstract Axial capacity analysis of deep foundations has been a topic of great interest in the soil-structure interaction problems. Soil behavior is governed by a series of complex stress-strain changes that occur during pile installation and subsequent loading. Owing to the difficulties and uncertainties on the basis of the soil strength-deformation characteristics, one of the most frequently followed design practice is to refer to the formulae correlating directly the pile axial capacity components of unit base resistance (qb) and unit shaft resistance (fp) to the data collected from cone penetration test (CPT). The elementary basis for such formulations has been the idea of considering cone penetrometer as a minipile foundation. This has resulted in plethora of correlative relationships in the past over 60 years. Such correlations, although empirical, have been worked out on the basis of load test results from both instrumented and un-instrumented full scale piles and are able to accommodate many important variables. A quick review of the evolution process and development of such design formulations is presented. An existing method is refined and modified to bring more convenience in extended applications. Few recommendations are proposed for future research directions, where the latest version of CPT i.e., seismic piezocone test (SCPTu) can be used to advance from capacity singularity to the complete axial pile load – displacement (Q – w) response.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133673846","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":"Ant Colony Optimization Method for Design of Piled-Raft Foundations (DFI 2013 Student Paper Competition Winner)","authors":"H. Yazdani, K. Hatami, E. Khosravi","doi":"10.1179/dfi.2013.7.2.002","DOIUrl":"https://doi.org/10.1179/dfi.2013.7.2.002","url":null,"abstract":"Abstract In comparison to conventional piled foundations, piled-raft foundations provide a more economical solution to support high-rise buildings constructed on compressible soils. In this type of foundation, the bearing capacity of the underlying soil is taken into account in supporting the superstructure loads, and the piles are placed to control both the total and differential movements of the superstructure. Currently, there are no universally accepted methods to design piled-raft foundations including the selection of the piles locations and dimensions. Most piled-raft foundation designs are based on empirical methods and the experience of designers. However, piled-raft foundations are massive and expensive. Therefore, developing methodologies for their optimal design could significantly help minimize their otherwise high construction costs and would make them more feasible and common practice. This paper examines the capability of the ant colony optimization (ACO) algorithm to optimize piled-raft foundations. The soil-pile interactions are taken into account by modeling the side and tip capacities of the piles using the nonlinear p-y, t-z, and Q-z springs in the OpenSees platform. The soil-raft interaction is taken into consideration using the Winkler springs beneath the raft. The objective of the optimization problem is to minimize the volume of the foundation by taking the number, configuration, and penetration depth of the piles, as well as the thickness of the raft, as design variables. The side and tip forces of the piles, the pressure applied on the underlying soil, and the total and differential movements of the foundation under the serviceability limit state are the constraints adopted for the optimization problem. Results indicate that the ACO algorithm is a suitable method for optimal design of piled-raft foundations. Findings of the study also indicate that including soil nonlinearity in the analysis (as opposed to a linear elastic soil model) can lead to a more economical design for these foundation systems.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129598872","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":"A Driveability Study of Precast Concrete Piles in Dense Sand","authors":"P. Doherty, D. Igoe","doi":"10.1179/dfi.2013.7.2.001","DOIUrl":"https://doi.org/10.1179/dfi.2013.7.2.001","url":null,"abstract":"Abstract A research study was recently completed by University College Dublin to examine the performance of various pile types including open steel tubular piles, concrete precast piles, and helical piers. At the outset of this project, one of the key risks identified was that the concrete piles could not be installed to the target depth due to (i) insufficient energy from the available hammer and (ii) the onset of pile material damage. In order to mitigate this risk a detailed pile driveability analysis was completed to predict the installation performance during driving. Selecting an appropriate model for predicting the Static Resistance to Driving (SRD) was seen as a critical component of the driveability process in order to predict reasonable stresses and blow counts. This paper describes the procedures adopted for a base case driveability analysis and the outcome of the pile installations. A comparison of the SRD using other models (including the API and IC-05 methods) was conducted and the results were compared to SRD profiles derived from dynamic pile monitoring conducted on one of the concrete piles. The base case driveability analysis indicated that the piles could be installed with the available hammer equipment, however it was noted that the driving stresses were relatively high and approached the failure stress of the concrete as the pile approached the target penetration. While hard driving was observed in the field, all of the piles reached their design depth of 7m (23 ft) with the exception of one pile which refused due to structural failure near the pile head. The driveability analysis and the measured stresses were interpreted to identify the cause of failure for the single pile, which was linked to the material properties of that specific pile.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131061087","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":"Grouted Micropiles for Foundation Remediation in Expansive Soil (8th Michael W. O’Neill Lecture)","authors":"J. Nelson, K. Chao, D. D. Overton, Z. Fox, Jesse S. Dunham-Friel","doi":"10.1179/dfi.2013.003","DOIUrl":"https://doi.org/10.1179/dfi.2013.003","url":null,"abstract":"Abstract Foundation underpinning is a common component of remediation schemes for distressed foundations on expansive soils. For many applications in expansive soil, micropiles have distinct advantages over other techniques. This paper will concentrate on the design and construction of micropiles in expansive soil. It discusses the nature of building distress and the relationship between foundation movement and soil heave. It presents methods for determining the factors that are required for the design of micropiles. Such factors include calculation of expected free-field heave, depth of soil wetting, and prediction of pier movement. A finite element program developed by the authors and others to determine pier heave and internal forces is presented. The input parameters that are required for pier analysis are discussed, and the nature of the output and the sensitivity of the results to the output are described. A case example illustrates the advantages of micropiles over other methods.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121453494","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":"Relationship between Installation Torque and Axial Capacities of Helical Piles in Cohesive Soils","authors":"M. Sakr","doi":"10.1179/dfi.2013.004","DOIUrl":"https://doi.org/10.1179/dfi.2013.004","url":null,"abstract":"Abstract The empirical relationship between torque measured during installation and pile capacity has gained a wide acceptance in the helical pile industry in the last few decades. This paper presents a theoretical model developed to estimate torsional resistance of cohesive soils to helical pile installation. The proposed torsional resistance model was then used to establish torque factor, Kt, a factor that is widely used in the industry. The results of the study indicated that the Kt factor is a function of the load path (i.e. tension or compression), pile geometry and soil properties. The assessed Kt factors in tension and compression were validated by the results of 74 installation records and full-scale helical pile load tests. A parametric study was also performed to qualitatively assess the relative importance of different parameters that affect the Kt factors.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131302200","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":"Commentary on the Selection, Design and Specification of Ground Improvement for Mitigation of Earthquake-Induced Liquefaction","authors":"","doi":"10.1179/dfi.2013.001","DOIUrl":"https://doi.org/10.1179/dfi.2013.001","url":null,"abstract":"Abstract The evaluation of earthquake-induced liquefaction has become a routine part of geotechnical engineering design. For a given project, if an analysis identifies a potential for liquefaction and the consequences of liquefaction are deemed unacceptable, then some form of hazard mitigation is required. Mitigation efforts may consist of removing the liquefiable soils, bypassing the liquefiable soils with deep foundations, structurally accommodating the deformations or strength loss caused by liquefaction, or preventing the onset of liquefaction through ground improvement. The fundamental ground improvement mechanisms for liquefaction mitigation include densification, drainage, and reinforcement. When evaluating, recommending and specifying various ground improvement methods for liquefaction mitigation, practitioners should understand the fundamental mechanics involved and applicability and limitations of the various methods. The DFI Ground Improvement Committee offers a review of the fundamental mechanics and commentary on the applicability and limitations of each method to provide clarity and guidance on the issues related to ground improvement for liquefaction mitigation.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126392097","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":"From the Editors and Publisher","authors":"","doi":"10.1179/dfi.2013.007","DOIUrl":"https://doi.org/10.1179/dfi.2013.007","url":null,"abstract":"","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130830104","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":"Ultimate Lateral Resistance of Piles in Cohesive Soil","authors":"L. Hazzar, M. Karray, M. Bouassida, M. Hussien","doi":"10.1179/dfi.2013.005","DOIUrl":"https://doi.org/10.1179/dfi.2013.005","url":null,"abstract":"Abstract The ultimate lateral resistance of piles in cohesive soil is studied using the well-known finite difference code, FLAC2D. The Modified Cam Clay (MCC) constitutive relation is adopted in the analyses to model the cohesive soil behavior, whereas the structural pile model with three degree of freedoms, available in FLAC2D library, is adopted to model the piles. The reliability of Broms's method, still used in the current design practice of piles under lateral loads, is verified. Comparisons between the ultimate lateral resistances of piles and those deduced from the graphs proposed by Broms (1964) are presented in graphs. Different factors thought to affect the lateral resistance of piles in cohesive soil, not adequately considered in Broms's method, such as clay stiffness, pile length, pile diameter and axial load are parametrically studied. A special concern is devoted to elucidate the effects of over-consolidation ratio (OCR) on the ultimate lateral resistance of piles in cohesive soil.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131229289","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":"TECHNICAL NOTE: Direct Solution of the Brinch-Hansen 90% Pile Ultimate Failure Load","authors":"D. Dotson","doi":"10.1179/dfi.2013.006","DOIUrl":"https://doi.org/10.1179/dfi.2013.006","url":null,"abstract":"Abstract In 1962, Kondner prepared several papers dealing with hyperbolic stress-strain response of cohesive soils. The following year, Brinch Hansen proposed 80% and 90% failure criteria for stress-strain behavior of cohesive soils. Fellenius was instrumental in popularizing these failure criteria for pile load tests and offered a direct solution equation for the failure load according to the 80% failure criterion. Since the 90% Criterion has been incorporated into the International Building Code, equations for the direct solution of the failure load at the 90% Criterion would be useful to practicing engineers. This Technical Note supplies the derivation methodology for the 80% Criterion and provides expressions to determine the load and deflection at failure for the 90% Criterion.","PeriodicalId":272645,"journal":{"name":"DFI Journal - The Journal of the Deep Foundations Institute","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125249244","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}