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By Dimitrios Polantzas P. E., Collin E. Sweeney E. I. T., Franklin M. Grynkiewicz P. E., Leili Javidanian P. E.

In the latest AASHTO design specifications, the Load and Resistance Factor Design (LRFD) method is prescribed for the design of retaining walls. However, inconsistencies arise when LRFD is used for retaining wall design versus the traditional Allowable Stress Design (ASD). Required toe embedment and wall loading demand vary greatly when the two design approaches are compared, all else being equal. This is due to application of linear load factors to properties that vary non-linearly in the design. These inherent inconsistencies are further intensified when introducing factors such as layered soil profiles, different wall types, groundwater elevation, and surcharge requirements. When applied correctly, these two design approaches, in theory, should lead the designer to the same result with little discrepancy, as they do with steel structure design. However, the use of the current AASHTO LRFD method for various geostructural retaining wall designs yields contradictory results that suggest existing retaining walls that have been successfully designed and constructed are unstable. Fundamentally, LRFD should be built on reliability-based calibrations; the successful past performance of existing retaining structures designed using ASD suggests that the LRFD approach requires considerable modification. The authors of this paper recommend that the current LRFD load factors be reviewed and revised based on more comprehensive wall performance data and wall type such that the difference between retaining structures designed using LRFD and those designed using ASD is eliminated.

Oct 1, 2022

By Reda Mikhail, M. Birkan Bayrak

The Washington State Department of Transportation (WSDOT) State Route (SR) 167/70th Avenue East Vicinity Bridge Replacement Design-Build project is located in Fife, Washington. This $40 million project consists of replacing the existing 70th Avenue Bridge over Interstate 5 (I-5) with a single-span bridge of about 220 feet long with approach embankments. The subsurface conditions along the new bridge alignment generally consists of alluvial deposits with high potential of liquefaction overlying glacially overridden deposits. In the early stages of the project, drilled shafts were considered as the deep foundation system; however, after an additional subsurface investigation is completed at the site, driven pipe piles were selected as the deep foundation system. Bridge abutments are supported by 24-inch diameter, 80-foot-long open-end driven steel pipe piles. The pile length was determined to bypass a relatively thick liquefiable zone and to tip the piles above what could be compressible soils. The use of advanced seismic analysis was instrumental in optimizing the pile length. The dynamic testing performed on numerous piles indicated what could be unique soil setup factors compared to those measured in local projects as well as those reported in national design manuals. Detailed discussions of the pile foundations design and construction is presented in this paper.

Sep 8, 2021

By Sameh M. Khella

This paper discusses the application of deep CFA piles for the foundation of structures in different ground stratifications with a focus on the application in Queensland region. Design, construction techniques and quality measures implemented during these procedures are described. Testing methods and verification of capacity, integrity and performance of these piles are also demonstrated. Case studies for this application are presented with an appreciation of this solution within the provided project conditions of each case. Examples of successes and challenges encountered over the course of application of deep CFA in Queensland are mentioned. Limitations of the technique and less favourable situations for its implementation are also highlighted.

Nov 1, 2022

By Suresh Chikati, Gangadharan Santhanam

Twin tunnels were constructed to a length of 863m using TBM in one of the underground metro projects. The tunnels pass through complex geological conditions (soil, rock and mixed conditions). This paper presents the consideration of volume loss and the corresponding ground settlement associated with the excavation of twin TBM tunnels by analytical and numerical methods. Empirical methods were used to calculate the ground settlement induced by the excavation of twin tunnels. The ground settlement values were directly derived from the two parameters: the volume loss and trough width parameter. These parameters are calculated based on the geological conditions at the tunnel face and tunnel overburden. The finite element software, Plaxis 2D was used to model the soil parameters with appropriate geological conditions. Twin tunnel excavation is simulated in Plaxis 2D and the effect of tunnelling on the ground was simulated by percentage volume loss. The suitable line contraction value was applied to the tunnel linings to simulate the volume loss. The surface ground settlement was directly obtained from Plaxis 2D. Instrumentation arrays were proposed along the twin tunnel alignment, to provide the ground settlement monitoring data within the influence zone of tunnelling activities. The derived ground settlement values from analytical and numerical methods were compared with the actual field instrumentation and monitoring data. From the field instrumentation data, the actual volume loss values were calculated. The compatibility of ground settlement and volume loss calculated using analytical and numerical methods and those measured using field instrumentation data is discussed in this paper.

Sep 1, 2022

By Charles M. Wilk, Lori Tiefenthaler

"Information presented in this paper can be used to support deep soil mixing, subsurface grouting and slurry wall technology as sustainable construction technologies. Ordinary Portland Cement (OPC) is the default cementitious material used by Deep Foundation Institute (DFI) Members for geotechnical work. Owners, engineers and contractors can contribute to the sustainability of a geotechnical project by increasing the use blended hydraulic cements and industrial byproducts to replace some of the OPC in mix designs. Sustainability is defined as the quality of not being harmful to the environment or depleting natural resources. Production of cementitious materials consumes natural raw materials and energy while also generating air emissions and waste. Life Cycle Assessments can be used to compare the relative environmental impacts of one cementitious material to another. Blended hydraulic cements (BHCs) are interground (or blended) mixtures of Supplementary Cementitious Materials (SCMs) with OPC. Commonly used SCMs include fly ash, ground granulated blast furnace slag (GGBFS) and limestone. Examples of industrial byproducts commonly used in geotechnical work include coal combustion residuals (CCR) (aka fly ash), and ground granulated blast furnace slag (GGBFS). Much of life cycle impact of these SCMs and industrial byproducts have already been borne by the industries that generated them. There is increasing awareness to LCA and sustainability of different materials used on projects. This is evident in the application of the Leadership in Energy and Environmental Design (LEED) program. The savings in environmental impact with the use of SCMs and industrial byproducts can make proposed use of these materials in a geotechnical project more attractive in terms of sustainability. This paper presents (a) information that compares published life cycle assessment data of OPC, BHCs, and slag cement (SC) to illustrate the potential benefits to sustainability and (b) general strategies for positioning a geotechnical application, use, project design or cementitious material mix as a more sustainable alternative"

Jan 1, 2017

By Rick Deschamps

"Fountain Slide is located approximately 10 mi (16 km) northeast of Lillooet, British Columbia, Canada, within the Coastal Mountain Range, and has been locally active since the 1970s. The project site is located near the base of the relic Tunnel Mountain landslide. The progressive movements have posed a significant challenge to British Columbia (BC) 99, the main north-south highway in the region. The slide began affecting the British Columbia Railway Company (BCR) tracks in the 1990s. In 2004, the Canadian National Railway Company (CN) acquired BCR and, during the next 11 years, undertook measures to stabilize the rail bed. Some of the measures undertaken include numerous track realignments, a shotcrete and soil nail wall, an anchored soldier pile-and-lagging wall, and adding a row of anchors to the wall. For many years, the measures had proved successful until mid-2014 when it was observed that the slide retrogressed uphill of the tracks. Since that time, the slide movements typically ranged between 5/32 and 0.4 in (4 and 10 mm) per day, leading to extreme distortion of the earth retention system and the need for frequent track realignment.In the spring of 2016, CN issued a request for proposals (RFP) for a designbuild solution with the expectations of: (1) a safety factor greater than 1.2, (2) considering only the currently identified retrogressive blocks that extend to about 200 ft (61 m) above the track; and (3) minimizing activities outside the current easement. It was also communicated that there was a possibility that a portion of the line may have to be abandoned if the proposed remediation was cost prohibitive.The fact that the existing slide was a small fraction of the relic slide was intimidating. The relic slide extended for approximately 1.0 mi (1.6 km) above the uppermost retrogressive block that was now affecting the rail line. Other areas of concern included:"

Jan 1, 2017

By Sumit Kumar Biswas, Moyukh De, Sibapriya Mukherjee

"The piles often are also subjected to lateral (horizontal) forces and moments. In fact, there are some structures where the primary function of piles is to transfer lateral loads to the ground. Proper analysis of laterally loaded piles is very important to the geotechnical and civil engineering profession.In the present investigation an experimental study has been carried out with free head short model cast iron hollow piles of outer diameter of 24 mm and L/d ratios of 8, 10, and 15. The experimental results have been supplemented by numerical techniques using PLAXIS-3D Foundation version 2.1 software. The results have been found to agree reasonably well with the experimental results. Further finite difference approach has been adoptedto reduce the computational time and to calculate the coefficient of modulus of subgrade reaction (?h) from the load- deflection data obtained from PLAXIS output at different pile depths. The parametric study has been extended for the non-dimensional form defined as flexibility ratio (F.R.),where ?h, L, Ep and Ip are the coefficient of modulus of sub-grade reaction, the embeddedlength of model pile, elastic modulus of pile material and the moment of inertia of model pile about the central axis respectively).The variation of coefficient of horizontal modulus of sub-grade reaction (?h) has been studied with respect to the following parameters for homogeneous soil system: relative density andL/d ratio. It has been found that the logarithm of flexibility ratio increases with increase inrelative density and increase inL/d Ratio. The values of ?h obtained by the proposed method have been, found to be close to the numerical results.As output of this research, graphs have been generated in respect of different parametric variations to gain an insight into behavior of piles under lateral load for short piles."

Jan 1, 2015

By John Vickers, William H. Hover, Paul C. Schmall

"Any sudden subsurface issue that threatens the stability of existing buildings or infrastructure is cause for immediate investigation and prompt remedial action. Nowhere is this more true than the nation’s dams and levees. A breach of any kind, no matter how small initially, has the potential to be catastrophic and impact a wide downstream area. Addressing the problem quickly and effectively is therefore critical. When a turbid water discharge developed from a rock drainage embankment at the toe of the earthen dam impounding Cannonsville Reservoir, near Deposit, NY, the source of the problem was quickly identified as resulting from an artesian water release from an underlying permeable silty sand and gravel formation during drilling of three exploratory boreholes in preparation for construction of a hydroelectric plant at the downstream toe area of the dam facility. Work was halted, intense 24-hour monitoring was implemented, and as a risk reduction measure NYCDEP began to draw down the reservoir’s total storage at a rate of a billion gallons per day. Input sought from contractors within the geotechnical community helped result in the design and development of a deep well system to control the artesian pressure. Once this primary objective was accomplished, modified compaction grouting was performed at the borehole locations to densify loosened soils, fill any voids created by the discharge activity, and seal off the permeable aquifer. This paper discusses the dewatering program, specialized drilling techniques required, monitoring and verification of pressures within the dam, and the grouting program.BackgroundCannonsville Dam, owned and operated by the New York City Department of Environmental Protection (NYCDEP), is located in Deposit, New York on the West Branch of the Delaware River and impounds the Cannonsville Reservoir. Built between 1959 and 1964, the dam has an impervious central and upstream core zone keyed into the glacial till foundation, a semi-pervious downstream embankment zone, and a rockfill toe and is approximately 2,800 ft (853.4 m) long and 175 ft (53.3 m) high. The dam is formed by two embankment sections. The left section forms the main embankment blocking the main river channel, while the right section is constructed over a topographic saddle or low ridge. Reservoir level is actively influenced by withdrawals through the West Delaware Tunnel, based on water supply need. Under normal circumstances, water is continuously discharged downstream to the Delaware River."

Jan 1, 2016

By Richard D. Luark, Fernanda S. Madrona

Designing temporary retaining systems that allow for deeper excavation amid the existing urban infrastructure has become a challenge. A 60-foot-deep excavation in downtown Seattle was required to construct five levels of below grade parking for a 35-story high-rise building, Tower 12, next to an existing 20-story tower with three levels of below grade parking, separated from the project by an 18-foot wide alley. The solution was to combine two temporary excavation support systems, soil nailing and anchored soldier piles, to work within the site constraints. Densely-arranged, short-length soil nails were used to support the upper 30 feet of the excavation, while the lower 30 feet of the excavation was supported with soldier piles combined with steeply-inclined, high-capacity ground anchors, which extended below the adjacent building foundations. The combined temporary support system eliminated the need for internal bracing, reducing construction cost and schedule. The performance of the combined soil nail and soldier pile system was monitored with an inclinometer and optical survey monitoring, which demonstrated the performance of the combined temporary support system. This paper provides a discussion of the advantages of combining different excavation systems and an analysis of movement monitoring data collected. SITE CONDITIONS AND PROJECT INFORMATION Tower 12 consists of a 0.45-acre development with 36-stories of mixed, residential and commercial use with four levels of below grade parking. The project site is bounded by the Cristalla Condominium to the north, Virginia street to the south, 2nd Avenue to the East, and an 18-foot wide private alley to the west. The One Pacific Tower Condominium, which has three levels of below grade parking, was located to the west across the alley. A site layout plan is presented as Figure 1. As shown in Figure 1, the construction of the west wall required a maximum 51-foot-deep excavation, from elevation (EL) 162 feet to EL 111 feet. Adjacent to the west wall, the existing alley grade varies from elevation 154 to 161 feet, leaving a narrow block of soil 18 feet wide and up to 42 feet high to be shored along the alley in order to reach the One Pacific Tower bottom of mat foundation at EL of about 120 feet. In addition to the existing One Pacific Tower Basement wall, site constraints included existing utilities along the alley such as an existing 4.5-feet wide by 7-feet high vault, with bottom at approximate EL 146 located 10 feet from the back face of the proposed Tower 12 basement wall.

Jan 1, 2019

By Shreya Vivek Hokam, Dr. A. I. Dhatrak, S. W. Thakare, Dr. Vivek S. Hokam

Construction in congested urban areas has necessitated tall and massive structures. In urban areas, it is common to construct underground structure nearby existing buildings. Selection of an appropriate support structure system to be implemented in the excavation in an urban area is heavily dependent upon the geotechnical conditions and safety of the surroundings and neighbouring structures. Urban Rail, popularly referred to as Metro Rail, has seen substantial growth in India in the recent years. More cities are experiencing the need for metro rail to meet their day-today mobility requirements. The metro structures involved deep excavation for foundations which induces the stresses and thereby alters the existing equilibrium and thus may affect stability of neighbouring structures considering safety point of view. Hence, design and execution of deep excavations become one of the important challenging tasks of any geotechnical engineer in the modern era. Further, it is important to control the ground movement in order to prevent the failure of excavations. This involves specialized foundation technologies, usage of sophisticated equipment and new methods in underground construction, safety and monitoring systems. In this paper the methodology used for protecting adjoining structures due to deep excavation for Nagpur Metro station is studied.

Sep 1, 2022

By Pathik Deb Mallik, Shyamal K. Mitra, Rajiv Kishore, Shuvranshu Rout, Manos De

"This paper presents a case study on the design and construction of a deep underground pit structure constructed inside almost a century old existing plant building. The complexity and challenge for the design and construction lay in executing the work in a difficult subsoil condition especially the presence of deep mica schist. The limited space availability in the existing plant for construction work without hampering regular production in other adjoining areas of the plant made the execution more challenging. Experience with difficult subsoil and proximity to old foundations entailed a non-conventional engineering approach while ensuring complete safety in spite of maintaining the normal operation.INTRODUCTIONTata Steel Processing and Distribution Limited (TSPDL) is a subsidiary unit of Tata Steel Limited (TSL) having a CR processing facility inside the premises of Tata Steel Limited. TSPDL intended to install equipment for a new slitting line inside the existing shed including construction of very deep structure called “loop pit” where the strips from cut CR sheets collect in the form of loops and are recovered as scrap. The entire plant is located within the shed of existing plant. The construction of all foundations including the loop pit is to be executed in the limited area without disturbance to normal production work in balance areas of the plant and also maintain safety and integrity of existing structures.The existing shed is an old structure constructed approximately 80 years ago. The building column foundations are gravity type design of brick masonry supporting only the vertical load from the columns. This type of foundation designed with no eccentricity of loading provides no allowance for implementing any foundation stabilizing design. The present project required civil construction for the new equipment foundations safely within this area."

Jan 1, 2015

By Karen J. Dawson, Francisco Johnson

"Pressure-grouted high strength helical displacement piles are a recently developed pile type that can be useful in conditions where noise or vibrations must be low or where access or clearance is limited. However, there is no information in the literature that can be used to estimate the soil resistance of these piles or production rates. To fill this information need, this paper presents a New Jersey installation case history and the results of static axial and lateral load tests on both pressure-grouted and ungrouted high strength helical piles at the case history site and trial installation locations in New Jersey and Washington State. Piles between 25 and 50 feet long comprised of steel shaft diameters of 4.5, 5.5, and 7 inches with equivalent grout column diameters ranging from 12 to 22 inches were tested. Lateral loads of up to 100 kips and axial compression loads of up to 700 kips were applied. The results of the load tests are compared to predictions of lateral deformation and axial resistance.INTRODUCTIONHelical piles have long been recognized as a useful foundation type in situations where noise and vibrations must be limited, or where there are access or clearance restrictions. Relatively well-documented design methods and torque to capacity correlations have been developed for the most commonly used helical piles, which are relatively small (typically shafts of 6 inches or less) with corresponding low load carrying resistance.With the increased need to construct in congested urban environments, there is incentive to develop helical piles with higher axial resistance. Seismic and other loading conditions also require lateral resistance, which is low for the typically small helical pile shafts. One method of increasing the soil resistance, both axially and laterally and at relatively low cost, is to place grout around the shaft. Injecting the grout under pressure through the hollow helical pipe section and out a grout port or ports located near the toe of the pile has the potential to increase the pile resistance significantly above that which can be achieve by gravity grouting. Not only does the pressurized grout push out against the surrounding soil, but the rotating helix helps to distribute the grout laterally. Unfortunately, little information is available in the literature to help designers estimate the resistance of grouted helical piles in general and none is available regarding pressuregrouted helical piles."

Jan 1, 2016

By Michael Frawley, Deana Ruud, Jessica Turner

Technology is allowing for new ways to mitigate risk associated with subsurface exploration and unanticipated subsurface conditions during construction. Unanticipated subsurface conditions have the potential to force delays and cost overruns on even the best-managed and well-executed projects. For more than a century, geotechnical professionals have documented the location and conditions encountered in hundreds of thousands of subsurface borings. Utilizing processes for compiling and managing data, owners can streamline site selection and receive access to a conceptual geotechnical model before field exploration takes place. Digitizing historical subsurface information allows for creation of an interactive, web-based platform combining publicly available information and culminating with the opinion of a local, experienced geotechnical engineer. This connectivity aids in the reduction of risks associated with unknown conditions on prospective project sites. Through this conceptual project study, we demonstrate how a project owner would be able to use a comprehensive desktop study to review the expected conditions prior to making a purchasing decision. Following the purchase, the expected conditions would be confirmed through traditional methods, confirming potentially problematic site conditions and the associated risks. INTRODUCTION Preliminary project planning is often based on assumptions made by the design team with regards to site suitability. After due diligence, site development is traditionally initiated by the owner or the owner’s representative when engaging a geotechnical engineer to perform a thorough subsurface exploration at a site. The data generated by the geotechnical engineer’s analysis of the site is required to design foundations, pavements and earth retaining structures and move the project from concept into design. This necessary, subsurface exploration can be time consuming, intrusive, and require significant resources, often when resources during construction seasons when resources are most limited. By leveraging historical data generated from previous subsurface exploration, a more thorough analysis of project risk can be developed prior to mobilizing a drill rig. Ultimately, preliminary budgets and designs are more accurate and geotechnical field exploration is more strategic. The geotechnical engineer’s role transforms from raw exploration and analysis to confirmation of anticipated conditions.

Jan 1, 2019

By Leena Korkiala-Tanttu, Noora Lindroos, Juha Forsman

"Construction works at the Helsinki city sea shoreline requires dredging and handling of contaminated sediments. Most of these soft dredged sediments are regarded as too poor quality material for earth construction purposes. Mass stabilization technology has been applied to improve the technical and environmental properties of the dredged sediment in order to utilize the material in construction. The treatment site presented in this article is placed in the West Harbor where the dredged sediments are disposed in basins, mixed with binders by mass stabilization and transported to utilization sites. The volume of these basins is about 90 000 m3. So far these basins have been used three times during the years 2011-2014. The most applied binder has been cement. Its high price and carbon footprint have encouraged use alternative binders. Other used binder materials include fly ash and end product of desulphurization from coal combustion, and fly ash from combustion of Estonian oil shale. The technical and environmental properties of stabilized sediments have been studies in the laboratory and in situ thoroughly. Some properties of the stabilized sediments which have been studied are: compression strength, modulus, hydraulic conductivity, leaching of contaminants, etc. The leaching test results show that heavy metal leaching is very low with all binder materials tested.1. INTRODUCTIONContaminated marine sedimentsMarine sediments in the coastal areas are often contaminated as a consequence of industrial and port activities, as well as the influence of cities located there. Construction activities and reclamation of shore line require dredging and handling of contaminated sediments since the level of contamination inhibit dumping of dredged sediments into the sea. Based on their technical properties, most of these dredged soft and watery sediments (clay, gyttja, etc.) are regarded as too poor quality material for earth construction purposes. Economic, sustainable and environmentally safe management of contaminated, dredged sediments is a key issue in many construction sites.In the City of Helsinki, mass stabilization technology has been applied to improve the technical properties of the dredged sediments in order to utilize the material in construction. Owing to stabilization / deep mixing / solidification, also the contamination is encapsulated in a monolithic solid of a high structural integrity. Thus, contaminants migration is restricted by the decreased surface area exposed to leaching.The treatment site presented in this article is placed in the West Harbor (a place of Helsinki called Jätkäsaari) where dredged sediments are disposed into stabilization basins, mixed with binders by mass stabilization and then transported to final utilization sites. The location and principle of these basins is presented in Figures 1-4. The overall volume of these four stabilization basins is about 90 000 m3."

Jan 1, 2015

By Donald R. Clark

"Drilled shafts are being used as foundation support for parabolic solar troughs at the Genesis Solar Project being constructed near Blythe, California. Three types of drilled shaft foundations are required for the project. At project build-out, there will be a total of 23,008 drilled shafts installed at the site. Preliminary designs for the axial and lateral capacity of the drilled piers were based on conventional geotechnical engineering methodologies and soil-structure interaction. The drilled shafts and subsurface conditions were modeled through the use of the computer program LPILE v6.0.Conducting lateral load testing of drilled shafts was considered appropriate to confirm or modify the geotechnical parameters used in the preliminary design. The lateral load testing program was conducted to provide site-specific test data that would allow the design engineers (both geotechnical and structural) to predict the actual performance and adequacy of the proposed drilled shaft foundations and improve the efficiency and hopefully reduce project costs.The lateral load testing was conducted within two solar fields at the site. Three pairs of drilled shaft foundations were installed in each field, instrumented, and laterally loaded to determine load-deflection response. A value-engineered option, proposed by one of the drilled shaft contractors, was also load tested. The results of the load-deflection data obtained in the field was used to modify the soil modeling used in the original L-PILE analyses and adjust the production drilled shaft lengths.Based on the results of the lateral load testing, the in-situ moduli of the subsurface soils were significantly increased over that assumed in the preliminary analyses. Based on the final soil-structure interaction analyses, the preliminary drilled shaft lengths were reduced by 2 to 2-1/2 feet. This resulted in an overall reduction of 55,654 feet of drilled shaft construction on the entire project, a savings of approximately 16.5% over the preliminary"

Jan 1, 2017

By Donald R. Clark

Drilled shafts are being used as foundation support for parabolic solar troughs at the Genesis Solar Project being constructed near Blythe, California. Three types of drilled shaft foundations are required for the project. At project build-out, there will be a total of 23,008 drilled shafts installed at the site. Preliminary designs for the axial and lateral capacity of the drilled piers were based on conventional geotechnical engineering methodologies and soil-structure interaction. The drilled shafts and subsurface conditions were modeled through the use of the computer program LPILE v6.0. Conducting lateral load testing of drilled shafts was considered appropriate to confirm or modify the geotechnical parameters used in the preliminary design. The lateral load testing program was conducted to provide site-specific test data that would allow the design engineers (both geotechnical and structural) to predict the actual performance and adequacy of the proposed drilled shaft foundations and improve the efficiency and hopefully reduce project costs. The lateral load testing was conducted within two solar fields at the site. Three pairs of drilled shaft foundations were installed in each field, instrumented, and laterally loaded to determine load-deflection response. A value-engineered option, proposed by one of the drilled shaft contractors, was also load tested. The results of the load-deflection data obtained in the field was used to modify the soil modeling used in the original L-PILE analyses and adjust the production drilled shaft lengths. Based on the results of the lateral load testing, the in-situ moduli of the subsurface soils were significantly increased over that assumed in the preliminary analyses. Based on the final soil-structure interaction analyses, the preliminary drilled shaft lengths were reduced by 2 to 2-1/2 feet. This resulted in an overall reduction of 55,654 feet of drilled shaft construction on the entire project, a savings of approximately 16.5% over the preliminary design.

By Mark D. Fuhriman, Parham Khoshkbari, Robert Fosse

Drilled displacement piles are becoming an increasingly common deep foundation choice for their relatively simple installation methods, applicability to a wide range of subsurface conditions, and versatility. The installation method includes drilling and displacement of the soil followed by delivery of fluid cement grout under pressure, and placement of steel reinforcing to complete the pile. Because the installation method uses blind processes that do not permit direct observation of the pile, it is desirable to employ redundant testing tools to complement good construction techniques and inspection practices to ensure integrity of the piles. This paper examines the use of a range of integrity testing tools used for pile installations at a major office campus development. Because the integrity of a drilled displacement pile and its performance depend to a large extent on the skill and experience of the installation crew, the paper explores how use of multiple practical tools, including automated monitoring tools on the pile installation equipment, thermal integrity profiling, and high-strain dynamic testing, ensure structural integrity of the completed piles and how redundant integrity testing methods complement good construction and inspection practices add confidence in the quality of the foundation system.

Sep 8, 2021

By Danny Winters, Wesley Schmutzler, Christopher Lewis, Matteo Bertoni

"SR 83/US 331 is a primary North/South roadway in Walton County that is a crucial link for tourism and commerce between the Walton County beaches and the heavily traveled I-10 corridor in the panhandle of Florida. The facility also serves as the primary hurricane evacuation route from southern Walton County. This 3.4 mile project involves expanding the current two-lane crossing of Choctawhatchee Bay to a fourlane facility to increase capacity and dramatically improve mobility within the corridor. One of the major goals of the project is to perform ground stabilization using Deep and Shallow Soil Mixing (DMM & SMM) along existing causeways. Ground stabilization is required due to the existence of moderately deep very loose soils that have settled considerably over the years. As a result, the Florida Department of Transportation (FDOT) incurred significant maintenance expenses and was unable to maintain an acceptable ride quality. FDOT considered soil mixing as one option to control this settlement. Quality Control for soil mixing relies heavily on the monitoring system used to control mixing parameters. This paper will examine in detail, the reporting of the Drilling Mate System (DMS) used to ensure the quality of each soil mixed element.INTRODUCTIONThe Florida Department of Transportation (FDOT) issued a Design-Build Maximum Price Request for Proposal (RFP) for the Choctawhatchee Bay Bridge expansion. The design-build (D/B) team of Skanska/Parsons Brinckerhoff was awarded the contract. The D/B team, in order to meet the unique deep ground improvement challenges of the Choctawhatchee Bay Bridge Project, selected Foundation & Geotechnical Engineering (FGE) as the engineer to design the ground improvement and TREVIICOS South (TIS) to execute the works.The FDOT in their RFP states that “either bridge or utilize a deep ground improvement method to stabilize the three segments of the existing earthen causeway” and “one possible method of deep ground improvement which is considered viable is deep soil mixing”. FGE developed a proposal to provide a unique rigid transfer platform to effectively stabilize the existing causeways. This platform (Fig. 1) consists of an upper 10 ft thick stabilized soil layer which transfers axial load to a series of deep columns. This robust system guarantees superior durability, ride quality and pavement condition and will exceed all required design and performance criteria including, “Less than 2 inches of settlement within a 1,000-foot section”."

Jan 1, 2017

By Donald Bruce, Alex Reeb, George Filz, Wesley Schmutzler, Mitsuo Nozu

"One million seven-hundred thousand cubic yards of deep mixing were installed to support an elevation raise of an earthen levee known as LPV 111, which is located in east New Orleans. The deep mixing was done by two contractors using somewhat different technologies, but producing elements of the same size. As part of the quality control and quality assurance program, 507 deep-mixed elements were cored and 5,082 specimens were strength tested in unconfined compression. This paper presents data from the coring and testing program. Very high percentages of the core run lengths were recovered, except during one period for one mixing technology. The coring methods are described, and reasons for the isolated episode of low recovery are discussed. The strength data show that the specification acceptance criteria were satisfied. Statistical parameters of the strength data are provided, and trends between strength and the following factors are discussed: depth, soil type, binder factor, and project-specific experience. Photographs of longitudinal cuts of core specimens are presented. Important lessons learned from this unusually large project are described.INTRODUCTIONThe Lake Pontchartrain and Vicinity Hurricane Protection system included a project known as LPV 111, which is an approximately 5-mile long segment of levee and floodwall located in east New Orleans along the Gulf Intracoastal Waterway and adjacent to Bayou Sauvage National Wildlife Refuge (Cali et al. 2012). The majority of the project consisted of a raise of an existing earthen levee from an existing crest elevation of about 18 ft to a new crest elevation of about 28 ft. The underlying soils were weak and compressible, providing inadequate support for the raised levee. Ground improvement in the form of deep mixing was selected to provide the necessary stability and settlement control for the raised levee.The US Army Corps of Engineers (USACE), New Orleans District, was the governmental agency in responsible charge of the project, including approval of design, construction, and payment. The lead designer was URS Corporation, and the general contractor was Archer-Western-Alberici (AWA), working in alliance with TREVIICOS South (Trevi), who, together with Fudo Construction (Fudo), performed the deep mixing.As part of the quality control and quality assurance program, over 500 production deep-mixed elements were cored, the cores were carefully logged, and over 5,000 unconfined compression tests were performed. In addition, selected specimens were carefully photographed before and after longitudinal saw cuts to expose the interior of the specimens. This paper provides a summary of the coring and testing performed on the production deep-mixed elements."

Jan 1, 2015

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