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

Part I: Selection and Design of Rigid Inclusions 第一部分:刚性内含物的选择与设计

DFI Journal The Journal of the Deep Foundations Institute Pub Date : 2023-11-01 DOI: 10.37308/dfijnl.20230303.279

Miriam Smith

{"title":"Part I: Selection and Design of Rigid Inclusions","authors":"Miriam Smith","doi":"10.37308/dfijnl.20230303.279","DOIUrl":"https://doi.org/10.37308/dfijnl.20230303.279","url":null,"abstract":"The use of rigid inclusions (RIs) as a ground improvement technology has become widely accepted as a cost-effective solution to support structures and embankments on sites with marginal, compressible ground. Rigid inclusion elements are defined as stiff, columnar, slender, vertical, discrete elements typically installed in regularly spaced groups. The term RI can apply to a variety of materials, but the primary focus of this paper is on cementitious, cast-in-place RIs. Thousands of structures throughout the United States are supported on RIs; however, there currently exists no industry-wide standard for the selection, design, and verification of RIs. When evaluating, recommending, and specifying RI ground improvement methods, practitioners should understand the fundamental mechanics involved, as well as the applicability and limitations of RIs. The purpose of this document is to provide commentary guidelines that address general concerns regarding the selection and design of RI systems for ground improvement. The development of this document is the result of a collaborative effort of the Rigid Inclusion Task Force of the Deep Foundations Institute (DFI) Ground Improvement Committee. This document (Part I) describes the fundamental mechanics of RIs for ground improvement and discusses the state-of-the-practice for the design of RIs in the United States. A subsequent document (Part II) will discuss construction and verification considerations of RIs.","PeriodicalId":304067,"journal":{"name":"DFI Journal The Journal of the Deep Foundations Institute","volume":"46 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132605737","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}

引用次数: 0

Editorial Note, Issue 1, Vol 17 – 2023 编者按，第1期，第17卷- 2023

DFI Journal The Journal of the Deep Foundations Institute Pub Date : 2023-01-01 DOI: 10.37308/dfijnlvol17no1.e

Jerry Bishop

引用次数: 0

Comparative Study on Ground Improved by Stone Columns and Ground Improved by Hybrid Concrete Columns 石柱改善地面与混合混凝土柱改善地面的比较研究

DFI Journal The Journal of the Deep Foundations Institute Pub Date : 2023-01-01 DOI: 10.37308/dfijnl.20220512.255

Chulmin Jung

{"title":"Comparative Study on Ground Improved by Stone Columns and Ground Improved by Hybrid Concrete Columns","authors":"Chulmin Jung","doi":"10.37308/dfijnl.20220512.255","DOIUrl":"https://doi.org/10.37308/dfijnl.20220512.255","url":null,"abstract":"This paper provides a detailed discussion and comparison of two deep ground improvement techniques, stone columns and hybrid concrete columns (HCC’s), in terms of design, construction procedure and performance, through a case history from a recent petrochemical project in Malaysia. Two full-scale group load tests (GLT’s) were conducted on test columns constructed prior to construction of production columns and used to calibrate the analytical models adopted for the design of stone columns and HCC’s. The ground improved by HCC’s shows a stiffer load-settlement behavior compared to the ground improved by stone columns as predicted by analytical models. In addition, the time-dependent settlement is more obvious in the stone column improved ground than in the HCC improved ground. Stone columns may act as a drainage path helping expulsion of pore water as the applied load increases whereas concrete columns transfer the load to the surrounding soils through the load transfer at the interface between a concrete column and the surrounding soil. The results of all four GLT’s on production columns confirm that the settlement predictions with the calibrated analytical models are satisfactory. This paper also summarizes the key calibration techniques adopted at the project site for quality control during construction. These calibration techniques can be considered as a useful guide for other project sites with similar ground improvement methods proposed in similar ground conditions.","PeriodicalId":304067,"journal":{"name":"DFI Journal The Journal of the Deep Foundations Institute","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126421657","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}

引用次数: 0

Experimental Investigation of Helical Pile Performance for Loess Deposits Improvement 黄土堆积层改良中螺旋桩性能试验研究

DFI Journal The Journal of the Deep Foundations Institute Pub Date : 2023-01-01 DOI: 10.37308/dfijnl.20221114.264

A. Eslami

{"title":"Experimental Investigation of Helical Pile Performance for Loess Deposits Improvement","authors":"A. Eslami","doi":"10.37308/dfijnl.20221114.264","DOIUrl":"https://doi.org/10.37308/dfijnl.20221114.264","url":null,"abstract":"Collapsible loess is classified as problematic soil found on most continents. The loess immediately collapses under stresses induced by axial compressive loading or the soil weight when exposed to moisture. In Iran, vast areas of the Golestan province are covered with Aeolian loess deposits. This paper investigates whether the simultaneous effect of inundation and pre-loading in helical pile installation is operative and effective in improving Golestan loess. The effect of installation conditions on loess collapsibility is studied via two main approaches, i.e., field investigations and physical modeling. The experimental studies include the installation of ten single and triple helix piles in the Amirkabir University of Technology Frustum Confining Vessel, i.e., FCV-AUT. Also, ten single and double helix piles with embedment depth of 3 to 6 m and a helix diameter of 250 mm were installed in Golestan province, and full-scale pile static loading tests were performed. The results indicated that the simultaneous application of crowd loading and water pressure during the installation of helical piles results in collapsibility potential reduction due to the soil treatment. Moreover, high or low crowd loads accompanied by water pressure during pile installation bring about similar load-displacement behavior of model piles installed in FCV-AUT and full-scale helical piles. Eventually, it was illustrated that the applied improvement technique is effective on loess soils since it uses the least amount of material, machinery, and equipment while attaining the highest possible bearing capacity ratio regarding sustainability.","PeriodicalId":304067,"journal":{"name":"DFI Journal The Journal of the Deep Foundations Institute","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122978636","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}

引用次数: 0

Dynamic Behavior of Helical Piles in Dry and Liquefiable Soils using Scaled Shake Table Tests 干液化土中螺旋桩动力特性的振动台试验研究

DFI Journal The Journal of the Deep Foundations Institute Pub Date : 2023-01-01 DOI: 10.37308/dfijnl.20210430.236

Milad Jahed Orang

{"title":"Dynamic Behavior of Helical Piles in Dry and Liquefiable Soils using Scaled Shake Table Tests","authors":"Milad Jahed Orang","doi":"10.37308/dfijnl.20210430.236","DOIUrl":"https://doi.org/10.37308/dfijnl.20210430.236","url":null,"abstract":"The dynamic behavior of helical piles with different numbers of helices as well as a single slender shaft was examined through a series of scaled shake table tests. Multiple shakings were applied during each test series to evaluate the seismic behavior of the helical piles and the slender shaft considering different response parameters. A considerable ground settlement was observed during the first shaking in each test series, whereas negligible helical pile and slender shaft settlements were measured during all tests. The dynamic response of the helical piles was evaluated based on their bending moment variation along the depth and various measured response parameters at the model superstructure level. The bending moment variation indicated a similar trend along the depth for the helical piles and the slender shaft: the maximum moment was consistently observed at the boundary between dense and liquefiable layers. The observed bending moments along the depth increased with increases in input motion amplitude and superstructure weight. Densification of the liquefiable layer during different test series reduced the maximum bending moment along the depth for each pile due to increased relative density. Increasing the number of helices enhanced the dynamic performance of the helical piles compared to the slender shaft in terms of maximum bending moment, maximum horizontal displacement, residual horizontal displacement, and superstructure acceleration in different ground conditions.","PeriodicalId":304067,"journal":{"name":"DFI Journal The Journal of the Deep Foundations Institute","volume":"221 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133349122","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}

引用次数: 0

Observations on the Seismic Loading of Rigid Inclusions based on 3D Numerical Simulations 基于三维数值模拟的刚性夹杂体地震荷载观测

DFI Journal The Journal of the Deep Foundations Institute Pub Date : 2022-12-23 DOI: 10.37308/dfijnl.20220513.256

M. Gibson

{"title":"Observations on the Seismic Loading of Rigid Inclusions based on 3D Numerical Simulations","authors":"M. Gibson","doi":"10.37308/dfijnl.20220513.256","DOIUrl":"https://doi.org/10.37308/dfijnl.20220513.256","url":null,"abstract":"Rigid inclusions are increasingly being specified in seismic regions to transmit foundation loads to competent strata at depth due to their ability to provide excellent static performance and potential for cost-savings over other forms of ground improvement and/or deep foundations. Despite their widespread application in seismic regions, the seismic kinematic interaction of rigid inclusions is not well understood. This study presents a series of parametric numerical simulations specifically conducted to capture the kinematic soil-rigid inclusion interaction under seismic loading to identify key mechanisms that contribute to seismic performance. The effect of ground motion variability, area replacement ratio, surface crust thickness, embedment into a competent layer, liquefiable layer thickness, and steel reinforcement is systematically investigated. Although the rigid inclusion may not prevent liquefaction triggering, severe amplification associated with dilation spiking of transiently liquefied soil is mitigated and the onset of liquefaction delayed due to the soil-rigid inclusion interaction. The role of static arching to alter the geostatic stress state prior to and during shaking is shown to be responsible for significant and heretofore unknown coupled fluid-mechanical interaction that drives the performance of the rigid inclusion within the reinforced soil system. The kinematic flexural demand following the triggering of liquefaction and phase transformation associated with cyclic mobility is met through transient increases in axial load, which increases the confinement of the grout comprising the rigid inclusion, and therefore its moment capacity. The complex mechanisms identified in this work should be used to help identify which subsurface conditions may lead to responses, guide design decisions regarding selection of reinforcement and embedment, and provide a basis for assessments of the anticipated kinematic demands in view of the beneficial axial load-moment capacity interaction following soil liquefaction.","PeriodicalId":304067,"journal":{"name":"DFI Journal The Journal of the Deep Foundations Institute","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130925928","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}

引用次数: 0

Determination of design parameters for solidification-stabilization soil improvement in retaining structures 支护结构中固化-稳定土改良设计参数的确定

DFI Journal The Journal of the Deep Foundations Institute Pub Date : 2022-12-23 DOI: 10.37308/dfijnl.20220801.261

Beijer Lundberg

引用次数: 0

Surface In-situ Stabilization of Saturated Ash for CCR Impoundment Closures CCR水库闭孔饱和灰表面原位稳定研究

DFI Journal The Journal of the Deep Foundations Institute Pub Date : 2022-12-23 DOI: 10.37308/dfijnl.20220316.252

P. Lear

引用次数: 0

Combined Side and Base Resistance in Rock-Socketed Drilled Shafts – A State of the Art Consensus 嵌岩钻井的侧基联合阻力——最新的共识

DFI Journal The Journal of the Deep Foundations Institute Pub Date : 2022-12-17 DOI: 10.37308/dfijnl.20221115.267

P. Axtell

{"title":"Combined Side and Base Resistance in Rock-Socketed Drilled Shafts – A State of the Art Consensus","authors":"P. Axtell","doi":"10.37308/dfijnl.20221115.267","DOIUrl":"https://doi.org/10.37308/dfijnl.20221115.267","url":null,"abstract":"Both side and base resistance contribute to drilled shaft rock socket axial resistance in most cases. While there are geological settings in which mobilization of side and/or base resistance may not be reliable, those situations are the exception, not the rule. The advent of bi-directional axial load testing of rock-socketed drilled shafts has resulted in a significant body of evidence regarding the independent behavior of side and base resistance mechanisms. Accordingly, over the last two decades, a wealth of data from these full-scale load tests of rock-socketed drilled shafts demonstrate this behavior when good design, construction and quality assurance/quality control (QA/QC) procedures are followed. The authors actively attempted to identify bi-directional test results to the contrary, including a survey of the entire Deep Foundations Institute (DFI) membership, but concluded there is a notable lack of evidence that side and base resistance do not mobilize simultaneously when proper design, construction and QA/QC procedures are followed in most geologic settings. Despite this fact, there are agencies and individual engineers that continue to disregard either side or base resistance for reasons that contradict available evidence, often resulting in excessive rock socket lengths that increase costs and the risk of problems during construction. The purpose of this document is to present a summary of the recent evidence indicating mobilization of combined side and base resistances at small, compatible displacements that are within the settlement tolerance of most structures in well-designed, constructed and inspected rock sockets. The recommended best practice for design of rock-socketed drilled shafts is to account for both side and base resistance unless there is a valid documented reason to disregard one or the other on a project-specific basis.","PeriodicalId":304067,"journal":{"name":"DFI Journal The Journal of the Deep Foundations Institute","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115431558","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}

引用次数: 0

Combined Effects of Liquefaction-Induced Lateral Spreading and Superstructure Inertial Loads on Pile Foundations 液化引起的横向扩展和上部结构惯性荷载对桩基的联合影响

DFI Journal The Journal of the Deep Foundations Institute Pub Date : 2022-12-17 DOI: 10.37308/dfijnl.20220512.265

Jared Martinez

{"title":"Combined Effects of Liquefaction-Induced Lateral Spreading and Superstructure Inertial Loads on Pile Foundations","authors":"Jared Martinez","doi":"10.37308/dfijnl.20220512.265","DOIUrl":"https://doi.org/10.37308/dfijnl.20220512.265","url":null,"abstract":"Pile foundations in sloping or gently sloped liquefiable soils are often subjected to a combination of inertial and lateral spreading loads. Current design codes vary significantly in terms of the methods used to analyze and design piles that are subjected to combined loading. The results from a full-scale shake table test on a 0.25-m-diameter reinforced concrete pile in gently sloping ground are used in this study to back-calculate the inertial loads, the kinematic loads, and the interaction between inertial and kinematic loads during seismic loading. It was found that large pile strains developed after liquefaction was triggered. The maximum pile strains (and curvatures) at shallow depths within the nonliquefiable crust were correlated with maximum inertial loads in the upslope direction that were resisted by a crust load applied in the downslope direction, indicating an out-of-phase interaction. The maximum pile strains (and curvatures) at deeper locations below the loose liquefiable sand were correlated with the maximum inertial loads in the downslope direction but without any resistance or driving load from the crust (i.e., no lateral spreading load during peak downslope inertial cycles). The lack of crust load during the downslope inertial cycles was attributed to the pile head outrunning the crust displacement, causing the pile to be pushed into a gap that had formed on the downslope front of the pile. The findings of this study contribute a data point to a wide range of inertial and kinematic interaction factors proposed by other studies and highlight the site- and project-dependency of interactions between inertial and kinematic loads.","PeriodicalId":304067,"journal":{"name":"DFI Journal The Journal of the Deep Foundations Institute","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116814664","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}

引用次数: 1