Search Documents

By Randy R. Williams, Roberto R. Olivera, Brian W. Wilson, Marina S. W. Li

"An extensive, deep mixing (DM) ground improvement program using the Cutter Soil Mixing (CSM) technique was designed and constructed in 2013 to support up to 20 m (66 ft) high Mechanically Stabilized Earth (MSE) walls and bulk earthworks for the development of the Kitimat Liquefied Natural Gas (LNG) facility at Bish Cove, British Columbia. The deep mixing program consisted of overlapping rectangular panels of in situ cement treated soils, constructed using the CSM technique, to form barrettes covering an area of approximately 12,900 m2 (15,428 yd2) and providing suitable static and seismic stability of foundation soils for support of the proposed MSE walls, which would in turn support LNG facilities. The deep mixing program comprised of 1645 CSM panels that were constructed through varying thicknesses and discontinuous layers of very soft fine-grained marine deposits and/or loose sandy silt to silty sand deposits, embedding typically 2 m ( 6.6 ft) into dense silty sand to sand and gravel. CSM panel depths ranged from 5 m (16 ft) to 30 m (98 ft) and were constructed by treating approximately 73,900 m3 (96,658 yd3) of soil yielding average unconfined compressive strengths exceeding 2.5MPa (363 psi).This paper outlines the approach adopted for the design of the CSM ground improvement program in the highly variable subsurface conditions present at the site. A phased sitespecific investigation consisting of boreholes, test pits, Cone Penetration Tests, piston tube sampling, advanced laboratory testing and groundwater monitoring was implemented. In addition, soil-cement bench scale testing was completed, followed by installation of 8 CSM panels for field trial purposes. Extensive geotechnical static and seismic analyses including Limit Equilibrium stability analyses, liquefaction assessments, and advanced numerical modeling were undertaken to optimize the design and meet the project-specific design performance criteria. The Design-Build team worked closely to develop and implement Quality Assurance and Quality Control plans and managed significant construction challenges while achieving suitable panel termination depths."

Jan 1, 2017

By Jogeshwar P. Singh, Mohamed Ashour

The Soil-Foundation-Structure-Interaction (SFSI) problem involves Kinematic Soil- Foundation Interaction occurring during large (cyclic and permanent) ground deformations as well as Inertial Foundation-Structure Interaction occurring during shaking all of which take place while the soil and possibly structural properties degrade with time. The design of the deep foundations for liquefaction induced lateral spread loads include estimation of passive pressure applied by the liquefied material as well as the amount of anticipated displacement. Coupled analyses for SFSI problems that account for liquefaction induced lateral spread and their interaction with the deep foundation system can be performed using sophisticated numerical modeling techniques based on finite element and/or finite difference methods using computer programs such as FLAC or OPENSEES. Such complete SFSI analyses are very tedious and expensive and not feasible for most projects. In 2011, California Department of Transportation (Caltrans) released guidelines for foundation loading and deformation due to liquefaction induced lateral spreading. This simpler prescriptive approach combines empirical and analytical methods through decoupled analyses using computer programs such as LPILE and SLOPE-W together with liquefaction induced lateral spread estimates based on published empirical equations. Pile group effects and pile caps are accounted for using a concept of super-pile. In this paper, we discuss the solution of the same lateral spreading related SFSI problem using computer program CGI-DFSAP (CGI-Deep Foundation System Analysis Program) based on the strain wedge theory that can account for liquefaction, lateral spreading, pile groups, pile caps and nonlinear behavior of piles in a more coupled manner to analyze the foundation system under the lateral spread loadings. CGI-DFSAP can be used to analyze piles in sloping ground conditions as well as piles beneath the abutments near a free-face slope. We have included Strain Wedge Model (SWM) solutions using CGI-DFSAP of several field and laboratory case studies of lateral spreading related to pile foundations. Finally, we have also included the SWM solution of one of the Caltrans (2011) example problems.

Jan 1, 2015

By Kyle Kershaw

Micropiles are routinely used in the United States for foundation support and stabilization of slopes. In recent years, several retaining walls have been constructed using micropiles in an A-frame type configuration to support temporary and permanent excavations at sites with limited access and limited right-of-way. Typical A-frame micropile walls consist of a row of vertical micropiles at the face of the wall and a row of battered micropiles extending into the soil or rock to be retained. The two rows are then tied together with a pile cap such that the front pile acts primarily in bending and the back pile acts primarily in tension. Because of tight right-of-way constraints at a residential site in Aspen, Colorado, it was not possible to construct the wall using conventional shoring systems or micropiles in the typical A-frame configuration. Rather, the wall was designed such that the row of battered piles was installed at the wall face and the row of vertical piles was installed adjacent to the property line behind the wall. As a result of the reverse configuration of the A-frame wall, FLAC, a two-dimensional, finite difference software program, was used to model the soil-structure interaction. The final wall design consisted of both temporary and permanent retaining wall sections with maximum heights of 26 feet. Inclinometers were installed in several piles to monitor the behavior of the retaining walls during and after excavation. This paper presents an overview of the design method, a discussion of construction techniques, and a comparison between the FLAC model and the measured behavior of the wall in the field.

Jan 1, 2007

By Derrick Dasenbrock

Two DFI committees independently organized two complimentary panel sessions for the recent American Society of Civil Engineers' (ASCE) Geo- Risk 2023 "Advances in Theory and Innovation in Practice" Conference in Arlington, Virginia, July 23-26. The Geo- Institute (GI) specialty conference welcomed more than 200 professionals and students interested in risk from around the world to the Washington, D.C., area for three full days of plenary keynote lectures, papers and no-paper sessions. The GI Risk Assessment and Management Technical Committee organized the event, which is the third in a series planned on a 6-year cycle. The previous two events were in 2011 in Atlanta and 2017 in Denver.

Sep 1, 2023

By Gary L. Seider, Dana A. Wesolek, Fred C. Schmednecht

"A new condominium project, The Atelier, developed by Pickus Companies located at the corner of Bryn Mawr and Sheridan in Chicago, IL required an earth retention system to protect the surrounding roads, alley, and existing neighboring apartment bui lding during its construction. Slurry Systems, Inc. (SSI) and Ground Engineering Consultants, Inc. designed the earth retention system using cantilevered sheet piling for three of the four sides: two sides bordering major streets and one side bordering an alley. For the fourth side, which borders an existing occupied brick building, a combination of sheet pil ing and AB. CHANCE® helical screw piers were used. SSI was actively involved in the review process of its earth retention system with the City of Chicago and quickly learned that there was no specific code for hel ical piers/anchors. (It appears that this is the case with most metropolitan cities throughout the United States). Consequently, the approval of underpinning for this project became the critical path, as much testing, calculations, meetings, and other details were required prior to its approval.SSI and AB. CHANCE® recognized that this process for underpinning approval must be seen by other contractors/suppliers who wish to use helical piers/anchors in the City of Chicago. Consequently, this project served as an opportunity to work with the City of Chicago and the City's Building Code Committee in furthering the development of the Helical Piers/Anchors Code, Section 1814. INTRODUCTION - HELICAL PIERSDefinition. A helical pier or anchor consists of one or more helix-shaped steel bearing plate(s) attached to a central steel stem (solid bar or pipe), which is installed by rotating or ""torquing"" into the ground. Each helix is attached near the tip, is circular in plan , and is formed into a screw thread with a defined pitch. Helical piers/anchors are pre-fabricated and can derive their load-carrying capacity through both end bearing and skin friction. The helical piers/anchors can be augmented with grout."

Jan 1, 2005

By John P. Turner, Benjamin J. Turner

"Non-destructive testing and evaluation (NDT/NDE) methods have become standard tools as part of the post-construction quality assurance of drilled shaft foundations. In responding to anomalies, foundation designers, owners, and contractors face a number of choices, including: (i) acceptance of a shaft with known anomalies, (ii) further investigations of integrity (e.g., concrete coring), (iii) repair schemes, and (iv) reject and replace. To assist in selecting the best option, analyses are often performed that involve assessing the structural performance of reinforced concrete shafts that may include defective concrete or voids. Currently, the analytical tools for predicting the flexural strength and stiffness of drilled shafts with defective concrete located in discrete regions of the cross section are limited. This paper presents a robust moment-curvature analysis tool for drilled shafts based on the fiber-element discretization method. The tool allows for consideration of anomalous or defective concrete regions in the shape and location that they are believed to exist in the shaft while considering explicitly the nonlinear material behavior of the intact regions based on expected material properties. A case study is used to illustrate the practical application of the analysis to drilled shaft projects.INTRODUCTIONImperfections such as defective concrete or accidental eccentricity of reinforcing cages are an inherent part of the drilled shaft construction process that will occur occasionally even when construction best-practices are followed. Petek et al. (2002), O’Neill and Sarhan (2004), Poulos (2005), and others have described the effects that construction defects can have on the axial and lateral performance of drilled shafts. Our industry has seen rapid progress in recent years in the development and improvement of tools for detecting drilled shaft anomalies, such as gamma-gamma and crosshole-sonic logging, sonic-echo testing, thermal integrity profiling, and even visual inspection with invasive video cameras. Nonetheless, in most cases the wealth of data from these tests is used by foundation engineers to make a fairly “black or white” decision—should the defects be repaired, or should the shaft be rejected? A third option that is not typically considered is to directly analyze the section, including anomalies, and compare the reduced strength and/or ductility to the actual project demands. This option takes full advantage of the data collected during integrity testing, and may provide a justifiable means for avoiding further construction costs and delays, whether for repair or replacement."

Jan 1, 2016

By John P. Turner, Benjamin J. Turner

"This report describes a research project for evaluating the applicability of the widely accepted 80 percent criterion for elongation of ground anchors to anchors with unbonded lengths exceeding 100 feet. This issue is driven by several recent projects involving ground anchors for landslide stabilization in which a significant percentage of the anchors did not meet the criterion that requires measured elongation during proof load testing of at least 80 percent of the theoretical elastic elongation. The projects involved anchor unbonded lengths in the range of 85 to 220 feet, which is outside the range traditionally used in practice, although anchors of this length are being used more frequently for landslide stabilization. The principal objective of this research is to address whether the widely accepted criterion of 80 percent elongation is applicable for such applications, and whether other factors affect the ability of anchors to meet the criterion.Analytical methods for predicting transfer of load along the length of steel strand due to friction loss are used routinely in the prestressed concrete industry. These analytical expressions provide a rational framework for quantifying changes in load due to friction along the length of a ground anchor in terms of a ‘wobble coefficient’ (K) as defined in Aalami (2004). Values of the wobble coefficient for ground anchors can only be determined by back-calculating from load tests, i.e., fit the value of K to the appropriate analytical expression based on the known test load and measured percent elongation. The analytical basis is first developed and shown to provide a tool for evaluating results of anchor load tests to determine the magnitude of expected elongation as a function of unbonded length. Next, a database of anchor load tests is used to back-calculate values of K for anchors with unbonded lengths in the range typically used in geotechnical applications (< 100 feet). These values of K are then used to calculate expected friction loss for anchors with high unbonded lengths (100 to 250 feet) to evaluate whether the 80 percent criterion is reasonable."

Jan 1, 2017

By Negin Khalili-Motlagh-Kasmaei, Paul O'Leary, Christopher J. Rothsiedl, Dimitar Ninesvski, Alexander Zöhrer, Vincent Winter

This paper presents the implementation of a digital twin for the vibro-replacement ground improvement process, as part of a digital construction site. The goal is to implement an evidence-based quality assurance for each produced element (column or point). The system uses a combination of planning data and real-time machine data collected automatically from construction equipment. In addition to the quality assurance, feedback is provided in a number of areas, e.g., condition monitoring of the equipment. The digital twin builds upon the real-time sensor and machine data, fused with metadata, to implement a digital model for the process. A hierarchical data evaluation, using rule-based Key Performance Indicators (KPIs), permits viewing of the spatial variation of data over the construction site. This permits the modelling of systematic variations in subsurface properties across the site, enabling the detection of anomalous individual elements, the diagnosis of their cause and the prediction of properties as construction proceeds over the site. All time-series data and KPIs are represented by standard classes of objects, leading to a generic coding of the data analysis; this minimizes the effort required to add additional sites and/or new KPIs. Examples are presented for a number of sites, where the system was used to identify anomalous columns.

May 1, 2022

By Louay Owaidat, Daniel Jabbour, Allan Frappier, Jose Gomez, Mark Stanley, Tino Maestas

The U.S. Army Corps of Engineers (USACE) is implementing a levee strengthening program along the Sacramento River East Levee (SREL) designed to correct 11 miles of deficient levees as identified by recent hydraulic and geotechnical investigations. The first project, the subject of this paper, completed in 2020 resulted in approximately 3.0 miles of improvements to the California Central Valley Flood Protection system. The project area lies along the east bank of the Sacramento River in Sacramento. The program consists of constructing cutoff walls through existing levee embankments to remediate levee through seepage and under-seepage. Key challenges included designing and constructing measures to remediate a 100-year-old legacy levee system, the presence of both industrial and residential properties immediately adjacent to the landside of the levee creating severe space and access limitations, and performing this work during the 2020 statewide mandate to shelter-in-place due to the COVID-19 pandemic. The project team of contractors, USACE, state and local agencies, and engineering firms partnered to bring this project to successful completion within budget and on schedule expending more than 60,000 man-hours with no lost time accidents. With the issuance of future planned contracts, the program will significantly reduce flood risk to the City of Sacramento.

Sep 8, 2021

By Diane Reid, Antonio Marinucci, Robin Mao

Super Cells are an innovative, open-shaped bi-directional static load testing device used to promote concrete flow during placement while utilizing greater cross-sectional area of the pile to achieve large applied axial loads at relatively low hydraulic pressures (≤ 250 bar). This paper describes the results of multi-level load testing performed on a sacrificial drilled shaft that was 3.8 m (12.7 ft) in diameter and 110.6 m (363 ft) in length for the Jiaxing-Shaoxing River Crossing Bridge that spans Hangzhou Bay in Shaoxing, China. The test shaft was instrumented with embedded strain gauges and telltale rods along with displacement transducers at the top of the pile to measure the load-induced displacements along the length of the shaft. Load testing was performed twice using a Super Cell placed near the tip of the shaft, prior and subsequent to tip post-grouting, and then again using a Super Cell placed higher in the shaft. The axial resistance for the tested conventional drilled shaft was more than 5 times greater than the estimated axial resistance. In addition, the axial resistance after tip post-grouting (347,100 kN (39,033 ton)) was about 5.3% greater than the ungrouted axial resistance (329,600 kN (37,050 ton)). INTRODUCTION During the past few decades, the magnitude of axial, lateral, and flexural loading has considerably increased due to updated design codes, larger superstructures, and the manner in which extreme event loading (e.g. seismic and scour) is incorporated into design. The diameter and depths to which bored piles or drilled shafts are constructed have increased considerably during the last three decades due to the advancements in equipment technology and capabilities. In addition, monoshaft foundations have become increasingly used, as one large drilled shaft is able to replace a group of smaller diameter piles connected by a cap. Correspondingly, adequate strata, for both side and end resistance, must be discovered/determined as well as achievable to be able to construct the required foundations to support the greater design demands. As design demands have increased, the need to ensure integrity, quality, and performance of a constructed drilled shaft has become ever more crucial. Load tests are essential to validate design assumptions of side and end resistances, to assess the behavior and load transfer characteristics of the constructed drilled shafts, and to evaluate construction methods. Load tests utilizing a bi-directional static load testing (BDSLT) device can achieve considerably large applied axial loads and can be performed more economically, in less time, and in a much safer manner than conventional top-down static load testing methods.

Jan 1, 2019

Jan 1, 1998

By Tanaya Deb, Sujit Kumar Pal

"Experimental investigations are carried out on failure pattern around 2D models of belled anchor piles in dry sand bed of density 15.60 kN/m3 under uplift. The models are having thickness ratio (Ts/Tb) = 0.28, 0.32, 0.38 and 0.46 and total 12 numbers tests are performed on models possessing 45° bell angle and shaft thickness 26 mm. The foundation bed is prepared with alternate dyed and non-dyed sand layers and continued upto reaching embedment ratio of 3, 4 and 5 for each width ratio. The failure points are presented with respect to meridian section of anchor in X-Y coordinate system and the equations formed are of polynomial of degree 3; and R2 values are near about 1. The developed wedge is implemented as three-dimensional axisymmetrical failure surface around similar 3D models. In the horizontal slice method vertical limit equilibrium is used for calculating weight of wedge and mobilized shear (as per Chattopadhyay and Pise, 1986) on the slip surface of each element. The summation of all elementary forces demonstrates gross uplift capacity. The initial and final failure angles are detected and parametric study is conducted on failure pattern as well as predicted net ultimate uplift capacity. Almost all the analytical data are within ± 10% variations with respect to the experimental results of uplift capacity which shows better correlations. INTRODUCTION Belled or enlarged base anchor piles are attractive and economic alternative to the geotechnical engineers for compressive load bearing capacity as well as tension anchorage. These types of anchors may be useful for foundations erected below ground water table. In light weight structures like radar tower, television tower, power pole and outdoor sign pools imbalance horizontal forces due to wind loads, are more than of those self-weight of those structures. Due to chronic tensile loads most possibly from wind loads and associated imbalanced cable tension, the legs of power transmission tower should be properly designed to be safe against resultant pull-out forces. In belled anchor pile, uplift is influenced by embedment ratio, diameter ratio; so, contributions of these parameters on failure surface influence uplift capacity. Balla (1961) first introduced non-linear failure surface in the pattern of circular arc based on Kotter’s equation (1903) and soil friction was assumed to act on slip surface. The predictive mathematical models established by Matsuo (1967), Rao and Kumar (1987), Chattopadhyay and Pise (1986), Saeedy (1987) and Ghaly and Hanna (1994); it was reported that net ultimate uplift capacity was combination of bulk weight of failure wedge and shear resistance along slip surface acting in opposite direction of wedge movement. From the literatures available till date, it reveals that the contribution of mobilised shear and weight of breakout wedge separately, demanding for more clarification depending on the on parameters like embedment ratio, diameter ratio."

Jan 1, 2015

By Sara Moshfeghi, Seyyed Majdeddin Mir Mohammad Hosseini, Abolfazl Eslami

"Due to variety of current pile bearing capacity methods based on the cone penetration test (CPT), for optimum design, it is necessary to evaluate the performance of such methods in different geotechnical conditions. Geotechnical databases including piling and in-situ testing records have been recognized as useful tools for analysis, design and economical construction. In order to evaluate pile bearing capacity methods, AUT-CPT&Pile database has been compiled including 450 full scale pile load tests and CPT sounding records. This database consists of different pile types with a relatively wide range of geometries and various soil conditions. Forty three records of piles driven in sand deposits were then employed to evaluate effects of ultimate capacity interpretation criteria from load displacement diagrams. The Davisson offset limit criterion, the Brinch Hansen 80% criterion and the load at the displacement of 10% of the pile diameter were compared to estimated capacities from ten CPT based design methods currently used in practice. The Brinch Hansen 80% criterion and the load at the displacement of 10% of the pile diameter lead to reasonable results, the Brinch Hansen 80% criterion showed less scatter. For evaluating the accuracy and the precision of CPT-based methods, the results were compared to estimated capacities. Results of comparison indicate that the CPT-based methods mainly predict the pile capacity withreasonable accuracy.INTRODUCTIONAmong the different approaches of estimating the pile bearing capacity, in-situ tests, especially, the cone penetration test (CPT) are favored due to the cone similarities with piles in modes of installation as well as fast and continuous profiling. This trend is practically well established where deep foundations are to be constructed in soft to medium subsoil deposits (Eslami and Fellenius, 1997; Mayne and Niazi, 2009).Employing different design methods results in a wide range of values which complicates the selection of an appropriate one to determine the pile bearing capacity. Several studies by Briuad and Tucker (1988), Eslami and Fellenius (1997), Abu Farsakh and Titi (2004), Schneider et al. (2008) and Eslami et al. (2011) confirm disparity of different design methods predictions. Thus, for optimum design, it is necessary to evaluate and compare the performance of current methods.Geotechnical databases are known as helpful tools in research and practical applications for optimizing analysis and design and are mainly used for management and interpretation of data, evaluation of design methods, calibrating LRFD or ASD design factors, etc. Pile lateral and axial load tests are examples of databases in geotechnical engineering. A summary of several CPT and pile load test databases is presented in Table 1."

Jan 1, 2017

By R. Bruce Patterson

The New Tacoma Narrows Bridge is a classic suspension bridge founded on concrete caissons. Caisson construction was complicated by the proximity of the existing bridge piers, only sixty feet away. High capacity plate anchors were used successfully to moor the new caissons in currents as strong as seven knots during construction.

Jan 1, 2013

"The development of non-destructive testing (NDT) methods for deep foundations occurred in several parts of the world, gradually coming together into the present state of the art. The compilation of this brief NDT history is the best effort of several knowledgeable members of the Deep Foundations Institute (DFI) Drilled Shaft Committee, coupled with the recollections of several historically important contributors to the science. It is not intended to be exhaustive, but rather concentrates on the origins of the methods in common use and on which this manual focuses.Modern NDT methods, and the spread of knowledge about them, have expanded through application to real foundations projects by the original researchers, sometimes inspired by their own curiosity, sometimes to respond to the cost and time limitations imposed by static testing, and sometimes to address the questions raised on research projects funded by large government agencies such as the Federal Highway Administration (FHWA) in the USA, and various European transportation agencies. Initial attempts were primitive by today’s standards, and equipment limitations often restricted successful application to relatively simple cases. As electronics improved and confidence in them increased, the early researchers began commercial promotion of their methods, published their findings in professional journals, and shared experiences at conferences held by such groups as the DFI, the International Association of Foundation Drilling (ADSC), the International Conferences on the Application of Stress-Wave Theory to Piles and other venues such as ASCE and Transportation Research Board (TRB) conferences.NDT methods were developed to fill a need to assess the quality assurance of deep foundation elements. New pile types and higher design loads prompted engineers to verify the safety of their foundations via additional testing during construction. Static load testing was the traditional method to assess performance, and this method has been used for centuries and perhaps even millennia.Relatively recent alternatives to static load testing for determining the capacity of drilled shafts include the bottom load test method. This method uses a jack embedded in the lower portion of the pile (bottom load test) and was first reported to be used from Canada in the early 1970’s (Gibson& Devenny 1973). The concept immediately caught on in Israel, where it was used as a quality control measure for small-diameter piles drilled in rock (then a new technology). The method was later patented in the US by Jorj Osterberg, and offered as a commercially available service in thelate 1980s (Osterberg, 1989)"

Jan 1, 2004

By Bernard H. Hertlein

"When the Deep Foundations Institute (DFI) was founded, quality assurance and quality control (QA/QC) of foundation construction was rudimentary. Nondestructive testing (NDT) was a nascent technology, known to very few people, and very limited in its capabilities and applications. In the four decades since the DFI became a reality, NDT researchers and practitioners have taken advantage of technological advances to improve those existing testing and analysis techniques, and to create new ones that have all contributed to the engineering body of knowledge. This has enabled contractors to improve the quality and reliability of their products, and engineers to design more efficient foundations.Through its regular series of seminars, publications and annual meetings, the DFI has been vitally important in educating the deep foundations industry about the capabilities and benefits of NDT methods. In turn, NDT results have helped the industry identify problems in deep foundation construction, determine the causes of those problems, and improve design constructability and construction practices to increase the quality, reliability and efficiency of all types of deep foundations. This presentation reviews the evolution of several important NDT methods, and the contributions that they have made to foundation quality.THE BEGINNINGSThe Deep Foundations Institute (DFI) was incorporated in 1976 in the State of New Jersey as a 501(c)(6) non-profit association. The DFI is a consensus organization of Contractors, Engineers, Owners and Suppliers involved with the design and construction of all types of deep foundations. The purpose of the DFI was and still is to improve the planning, design and construction of deep foundations by educating all those involved, sharing best practices, and promoting the adoption of new technologies that improve quality, productivity or safety.This is well expressed in the current DFI Mission Statement: To bring together multi-disciplined individuals and organizations to find common ground and create a shared vision and a consensus voice for continual advancement in the deep foundations industry.At the time the DFI was born, nondestructive testing for verifying the quality and integrity of deep foundations was in its infancy, its growth constrained by the technology, or lack thereof. Some visionary engineers of the time understood the physics of the potential methods, and therefore the possible capabilities, but were frustrated by the lack of technology to work with. Electronic equipment was mostly analog, and the few digital data acquisition systems that were available had such slow sampling rates that they were incapable of recording rapid event sequences or short duration events such as those used in modern integrity tests. For example, Jean Paquet, a leading research engineer at the French National Construction Institute, (Centre Experimentale de Recherche et d’Etudes du Batiment et des Travaux Publics, or CEBTP) patented the frequency-based analysis procedure for the Transient Dynamic Response (TDR) method, aka Sonic Mobility or Impulse Response, in 1974, but it was not until 1977 that analog data acquisition systems became fast enough to turn his theory into a reality."

Jan 1, 2017

By S. Y. Fantaye

This paper discusses the design, construction and performance of a 30 inch thick diaphragm wall recently constructed in Baltimore, Maryland at Inner Harbor East. The project site is an established marina and waterfront property. The geologic profile consists of fill, alluvial silt and clay, Potomac sand and clay, decomposed rock, and weathered rock on top of gneiss bedrock. The approximately 1,300 ft long perimeter diaphragm wall serves as a water cut-off, perimeter basement wall and support of excavation for the high rise project?s five levels of below-ground parking. Due to the fast track construction and the tight schedule, the initial design of the diaphragm wall was based on a limited amount of geotechnical information. Supplemental borings were then performed along the alignment of the wall to verify the design assumptions and wall depths. Additionally, the design criteria required that the wall be keyed into a competent stratum with low permeability. The Engineer of Record for the diaphragm wall, Mueser Rutledge Consulting Engineers (MRCE) completed the design and produced accelerated construction documents allowing the developer to release the drawings early for bid. This paper describes the theoretical soil parameters used to develop the loads, moments, and shears for the design of the diaphragm wall and the temporary tieback anchors. It also discusses the refinement of these soil parameters using the observed wall displacements and tieback pre-stressing forces as a baseline. This paper compares the calibrated parameters to the values used in the design of the wall. It explains how the soil structure interaction model was developed and the soil parameters calibrated using PLAXIS 2D non-linear finite element software. The paper also discusses the use of the proprietary CWS joint by Soletanche/Inquip JV as end stop between consecutive wall panels and the unique top-down construction utilized to support the diaphragm wall at the Southeast double re-entrant corner.

Jan 1, 2008

By Shahriar Vahdani, Andy Herlache, Andrew Bro, Wei-Yu Chen

"The Presidio Parkway Project will reconstruct approximately 1.6 miles of highway, including seven bridges, three cut-and-cover tunnels, and an undercrossing connecting the Golden Gate Bridge to the City of San Francisco, California. The project site is approximately 5.6 miles from the San Andreas Fault, which is capable of producing magnitude 8 earthquakes. Seismic hazards include strong ground shaking, soil liquefaction, ground settlement, and lateral spreading. At the Tennessee Hollow bridge section up to 30 feet of loose sands and soft clays are present. Concerns are raised that standalone drilled piers will experience excessive lateral soil loads from liquefaction-induced lateral spreading pressure resulting in excessive pier head displacement of up to 8 inches. Ground improvement by Cement Deep Soil Mixing (CDSM) is proposed to provide additional foundation stiffness. This paper presents the methodology to: 1) assess the effectiveness of the ground improvement in resisting lateral spreading, and 2) optimize ground improvement design at individual bridge bents based on local site condition. A series of 3-D numerical analyses are conducted and the results show that drilled piers with CDSM ground improvement are capable of withstanding seismic demands from lateral spreading and the lateral pier head displacement is reduced to less than 2 inches. The adopted analytical approach is efficient at modifying design for individual bents and can be considered for future pier foundation design in seismically active areas. IntroductionThe Tennessee Hollow bridge section (Low Viaduct) is an integral component of the Presidio Parkway project which will replace the existing facility with a new multi-lane roadway between the Golden Gate Bridge and the City of San Francisco. As shown on Figure 1, the project site is located about 5.6 miles east of the San Andreas Fault and 12.5 miles west of the Hayward Fault. The Low Viaduct will span over a future wetland habitat subject to tidal fluctuations and potential scouring."

Jan 1, 2014

By Steven D. Scherer

The highest earthquake risk in the United States east of the Rockies is along the New Madrid Fault System, which extends for 193 km (120 miles) through the Central Mississippi Valley from northeastern Arkansas, through southwestern Missouri, western Tennessee and western Kentucky to southern Illinois. Historically, this fault has generated some of the most powerful earthquakes in U.S. history, notably three Magnitude 8 events in 1811. Apart from the West Coast, this region experiences more earthquakes than anywhere else in the United States, with more than 200 events recorded along the fault annually. These events are typically of much lower magnitude than those experienced in California. Most are too small to be felt. However, should a significant event occur, damage can be expected to be widespread because of the underlying geology. In recent years, earthquake preparedness and seismic upgrade of vulnerable structures has become a focus for a number of State Departments of Transportation, including those in Illinois and Missouri where there is a potential for future damage. This paper presents three case histories illustrating three different techniques used to retrofit interstate highway bridge foundations bearing on potentially liquefiable soils. Friction minipiles were installed at the approach span of the I-57 bridge crossing the Mississippi River near Cairo, Illinois to provide additional support to the pile caps in the event of liquefaction of the underlying sands during a seismic event. In St Louis, Missouri, rock-socketed minipiles were installed to increase the capacity of drilled shaft foundations supporting a section of Interstate 64. In Mounds, Illinois, compaction grouting was used to densify loose sand deposits beneath a pile-supported interstate bridge on I-57.

Jan 1, 2001

By John P. Turner, Mark Jen, Bobby Daita

"The Port Authority of New York and New Jersey is replacing the existing Goethals Bridge built in 1928 which is deemed to be functionally obsolete. The replacement bridge will consist of a dual cable-stayed Main Bridge crossing the Arthur Kill with elevated approach spans connecting Elizabeth, New Jersey and Staten Island, New York. The main bridge towers are supported on a group of six nine-foot diameter drilled shafts that transition into a pier cap. The anchor and approach piers are supported on two column bents with each column supported on a single drilled shaft. The 4.5 to 10 feet diameter drilled shaft foundations have permanent steel casing to rock and socketed into bedrock. Subsurface conditions consist of Passaic Formation bedrock overlain by varying thicknesses of overburden soils. The foundation design assumes permanent casing extending a minimum 2 feet into the weathered bedrock. Rock socket lengths below the permanent casing vary between one to two shaft diameters based on the quality of the bedrock. The reinforcing design was based on AASHTO LRFD minimum requirements, force demands, seismic detailing requirements and also considering the continuity between the shaft and socket.The bridge is currently under construction with approximately 70 percent of the foundations installed. Several field conditions encountered at various stages of shaft construction between casing advancement and concreting required design and construction modifications. Based on the driving method and the quality of the bedrock, the tip of the permanent casing hit refusal either above or below the design elevation, requiring modifications to the drilled shaft design and its reinforcement. This paper provides an overview of the general subsurface conditions at the site and its impact on foundation design and discusses the detailing worked into the design to accommodate tip elevation variations, as well as various foundation design modifications in response to actual conditions encountered during construction."

Jan 1, 2016