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By Dave P. DeClerck

Hardman Construction was faced with the challenge of completing a large earth retention project on a constricted downtown Detroit site, while maintaining a safe and productive worksite. To do so, new technologies using robotic equipment was instituted. HISTORY The historic J.L. Hudson Building (Hudson’s) in Detroit, Michigan was the premier retailer in the city’s downtown district from the 1890s through the 1960s. The massive flagship store sat at 1206 Woodward Avenue, one of the busiest streets in the Detroit area. Hudson’s broke ground in 1891 and would go through twelve renovations and expansions. The last renovations took place in 1946, which gave the building the title of being the largest department store in the world at the time. It spanned an entire city block and boasted 2.2 million square feet of retail space. By the 1970s, Detroit was in an economic downturn. The Hudson’s department store finally closed its doors in 1983. Besides a few working offices, the building sat vacant. The building was unique in that it had four levels underground, offices, mechanical areas, and equipment storage. Following years of neglect, the Hudson’s building was seized by the state and transferred into the hands of the city. The city had it demolished in 1998, (shown in Fig. 1) to construct a new, four- level underground parking garage as well as a potential future above-grade development (Sewlck, 2017). The building was imploded in one of the largest implosions of that time. The building rubble filled the underground rooms and helped to stabilize the exterior concrete walls and keep them from collapsing.

Jan 1, 2019

By Jeffrey Goodwin P. E., Melih Demirkan Ph. D. P. E., Kevin Tehansky P. E.

Just an hour drive down MD 301 from National Harbor, construction to replace the Governor Harry W. Nice Memorial/Senator Thomas ‘Mac’ Middleton Bridge (HNB) began in spring of 2020. The Maryland Transportation Authority (MDTA) contracted with Skanska-Corman-McLean (SCM) to deliver a new US 301 bridge spanning 1.9 miles from Maryland to Virginia over the Potomac River aiming to improve capacity, safety, and access of the roadway. The project area presented a geotechnical design challenge due to the installation of new bridge foundations in the problematic soils of the Atlantic Coastal Plain alluvial deposits. With the existing bridge remaining in service during construction, and the site’s logistical constraints placing new pile driving operations near existing abutments and piers, a complex instrumentation and monitoring plan was developed to ensure public safety throughout the project. This paper discusses the geological conditions of the project area, the collaborative approach of various design team members to develop an appropriate monitoring plan utilizing various instrumentation, an understanding of baseline conditional movements of the existing bridge, and impact response of adjacent construction activity to help deliver effective new bridge foundations while protecting the old ones.

Oct 1, 2022

By Mohammed Faizal, Abdelmalek Bouazza

"The operation of ground source heat pumps combined with foundation piles can have an effect on the thermal behaviour of the pile and the surrounding soil. This paper presents the effects of continuous heating, continuous cooling, and alternate heating and cooling operations on ground and pile temperatures as well as the thermo-mechanical behaviour of a field scale energy pile. The effect of pile operation on the ground temperatures is highest near the pile and reduces with increasing radial distance. The results of the present studies generally showed that the thermal elasticity of the pile is not affected.INTRODUCTIONGeothermal energy piles are foundation piles used as underground heat exchangers to maintain thermal comfort in buildings, via the use of ground source heat pumps (GSHPs). Ground source heat pumps are more economical and environmental friendly compared to conventional heat pumps. Energy piles can be combined with supplemental surface heaters or coolers, known as hybrid systems, for forcefully recharging the ground during non-operational times of the GSHP. Alternative heating and cooling of the GSHP improves geothermal energy usage and alleviates heat build-up in the ground and provides a balance of ground temperatures around the heat exchanger (Jalaluddin and Miyara, 2012).The temperatures induced in the piles during GSHP operation can lead to a complex response of thermal strains and stresses in the pile concrete. An assessment of the thermo-mechanical response of energy piles for various thermal loads may assist engineers in the design process. Furthermore, an assessment of ground temperatures will also highlight any potential thermal interactions with other energy piles in actual building operations.At present, the thermal strain and stress distribution in field scale energy piles has mostly been studied for continuous operation (Laloui et al., 2006; Bourne-Webb et al., 2009; McCartney and Murphy, 2012; Akrouch et al., 2014; Mimouni, 2014; Murphy and McCartney, 2014; Murphy et al., 2014; Wang et al., 2015). These studies have contributed considerably to the understanding of the axial thermal strain and stress distributions in the piles and have shown that pile thermal behaviour is mostly thermo-elastic without inducing major structural concerns.The present paper adds to the current knowledge by assessing the pile thermo-mechanical and ground thermal response for continuous and alternating thermal loads of a field scale energy pile. The operation modes studied are 24 hours continuous cooling (Faizal et al., 2015), 24 hours continuous heating, (Wang et al., 2015) and alternate heating and cooling operation (Faizal and Bouazza, 2016). The forced ground thermal recharging is done during the non-operating times of the cooling unit, simulating a solar hybrid GSHP system for a scheduled intermittent mode of operation."

Jan 1, 1900

By Dominic Ammon, Mark Rothbauer, Paul Landers P. E.

Across the Potomac River from the location of the DFI47 Annual Conference (October 2022), in Alexandria, VA, two large permanent anchored walls with a decorative shotcrete face were recently constructed for the North Hill project, a new multi-family and townhome development. The project was executed with a design-build approach for the Fairfax County Redevelopment and Housing Authority with review by the Fairfax County Geotechnical Review Board. The project was constructed in highly variable Potomac group sediments that include high plasticity clay/silt terrace deposits overlying coarser grained materials. The soils were over consolidated and exhibited potential for slickensides from relief of horizontal stresses from past erosion. The wall system was designed to include deep soldier piles and permanent long strand anchors considering past slope instability in the area. As the construction progressed, problematic soil conditions and water issues required modifications to drilling methods. The two permanent walls spanned 800 and 1,000 feet long with a maximum height reaching 40 feet.

Oct 1, 2022

By David Guy, John Stanbury, Gilbert Tallard

"In 2009, storm surge from Hurricane Sandy inundated the Bay Park Sewage Treatment Plant located at El. +4 to +12 (+1.2 to +3.6 m) in East Rockaway, Long Island, NY. With all systems down, raw sewage water mixed in the floodwaters. A recurrence of such an event being unacceptable, and in view of rising future sea levels, a flood protection project was developed by Nassau County with funding coming in large part from the federally funded Sandy Rescue Fund. Designed by Arcadis/Hazen & Sawyer Engineers J.V., the protection took the form of a perimeter barrier capable of withstanding future storm surge. Due to limitations imposed by property lines and existing facilities, a levee design with three different types of cross section was developed to adapt to each location, adding construction complexity. The Long Island subsurface is characterized by beach sand extending to great depth. The clay required for the core and levee cover therefore had to be brought in from out of state. A thin silty clay layer at El. -23 to -25 (-7.0 to -7.6 m) served as an aquitard. The under-seepage was reduced by a hanging cut-off wall designed as a vibrated beam thin wall and filled with a salt water resistant, low permeability, self-hardening slurry.INTRODUCTIONOn October 29, 2009, Hurricane Sandy hit New York City, with a devastating effect on the region. The low lying Bay Park Sewage Treatment Plant (STP) (Fig. 1) serving Nassau County on Long Island was submerged (Fig. 2). All basements and underground mechanical facilities were flooded (Fig. 3) and millions gallons of effluent were released into the waters of the nearby Hewlett Bay which connects via other small waterways to the Atlantic Ocean."

Jan 1, 2016

By Chul Soo Park, Juhyung Lee, Duhyun Baek

"In this study the preliminary design of suction pile as the supporting system of the concrete floating structures was performed at the offshore pilot project area in Korea. The suction pile of the floating structures has to satisfy the lateral resistance against external force evaluated from the marine and structure conditions, as well as the penetration ability according to the soil and seepage conditions. In the design, the required penetration depths for lateral resistance were evaluated with different diameters of cylindrical steel suction pile, and the design suction pressures at each penetrating depths were assessed through the comparison of penetration forces and penetration-resistances. Finally, the optimal dimension of suction pile for the pilot project area was proposed.IntroductionInterests in sea spaces have rapidly increased around the world due to limitations in use of lands. Such increase has resulted in construction of numerous marine structures aimed at expanding the use of sea spaces and developing marine resources. South Korea also needs to secure construction technologies for floating infrastructures on its relatively deep seas. Foundations for floating structures consist of anchors and mooring systems rather than driven piles or cast-in-place piles, due to limitations in equipment operation or economic feasibility. Anchors and foundations used on the sea include drag anchors and suction piles, but the suction piles are more widely used for reasons regarding uncertainties of calculation of bearing capacity and construction. Large-diameter suction piles are generally used to utilize fully their penetration ability, which is proportionate to the square of the foundation diameter, and the length-diameter ratio (L/D) does not exceed 6 (Randolph et al., 2005; Andersen et al., 2005). Recently, a design and construction technology using group suction piles consisting of medium-diameter suction piles and concrete pile caps is being developed as an alternative to the conventional large-diameter mono suction piles. In addition, pilot projects involving the group suction piles of mediumdiameter are currently being reviewed for the southwest coast area in Korea. In this study, therefore, preliminary design for installation of medium-diameter mono suction piles as the supporting system of the concrete floating structures was performed, and suction pressures, penetration forces and resistances, and lateral loading capacity with diameters were reviewed."

Jan 1, 2017

By Patrick J. Lydon, Gregory A. Terri

"The recently opened Mansueto Library at the University of Chicago campus was a 2012 OPA runner-up. The dramatic elliptical shaped dome of this structure tells only part of this structure’s story. The underground automated storage and book retrieval system below ground required excavations as deep as 55 ft (17 m). The system that allows the University to store many of its publications well below grade also required an approximately 50 ft (15 m) clear span for the perimeter walls between the lower level and street level slabs. The latter requirement allows the conveyors to operate freely to retrieve and transport publications up to the lobby level. The design-assist-build team worked together to develop the most cost-effective solution for below-grade work in this challenging urban and geologic environment.The perimeter of the new oval-shaped library is over 620 ft (189 m) long and sits in a central location on campus—adjacent to the Regenstein Library and two city streets and the Henry Moore sculpture, which commemorates the location of the first self-sustaining controlled nuclear reaction. The new library construction not only had to meet challenging structural and geotechnical requirements, but also had to be sensitive to its active and historic surroundings. The soils at the site consist of about 25 ft (7.6 m) of sand, followed by lean clay, generally increasing in stiffness to the top of the dolomitic limestone. Five to 10 ft (1.5 to 3 m) pockets of saturated sand also lie on the north side of the site at about 45 ft (13.7 m) below grade. The top of weathered rock varies in elevation from 59 ft (18 m) below grade in the south to 69 ft (21 m) in the north. There is 1 to 2 ft (30 to 60 cm) of weathered rock. Groundwater at the site is about 7 ft (2 m) below grade.The new structure would extend 55 ft (17 m) below grade through saturated sand strata and into weathered rock for part of the structure’s footprint, so it was critical that the new permanent retention system minimize groundwater seepage laterally through the structure’s wall as well as piping through the weathered rock below the structure. The perimeter walls had to be very stiff to minimize ground movement around the structure’s perimeter due to the significant clear span between slabs."

Jan 1, 2013

By RavikiranVaidya, Vishal Dhamecha

Low Strain Pile Integrity Testing has been used in India since 1990’s and several have tried to demonstrate the utility and benefits of this method. However, use of this technology was limited till 1998 as not enough data maybe was not available to justify its use and application on major infrastructure and real estate projects. The first author has done significant work in this method resulting in its use in practically all sectors of the industry that use concrete bored pile foundations as a supporting element. The paper explains various signal enhancers or modifiers involved in processing of low strain test data and its implication on the final output. It also describes how the method can lead to abuse or can provide poor interpretation if incorrectly used. The current effort is to demonstrate that data collection and evaluation becomes complex with changes in soil stratum and pile profile. The paper highlights the present testing practices and provides a guideline for classification of pile integrity into few simple categories in Indian context rather than writing complex interpretations.

Sep 1, 2022

By Jack Taggart, Chris Barker

Pile load testing strategies for large infrastructure projects and multi-phase building developments have historically justified cost and programme benefits for undertaking advance preliminary and working pile load testing. However, more recently piling and pile load testing strategies have included assessment of the embodied carbon to understand and present the carbon savings that can also be achieved. This paper gives an overview of the factors contributing to carbon and emissions in the construction of bored pile foundations and presents the methodology taken in assessing embodied carbon as part of the pile load testing strategy for a multi-phased building development in London. Potential embodied carbon savings for various bored pile types and load testing strategies are discussed alongside alternatives and other considerations including pile re-use and carbon offsetting to inform continual improvement for future projects.

May 1, 2022

By F Debidin

The progressive rise of an H-pile during driving of an adjacent pile is described in this case history in which piles 15 to 18 m long were driven to end-bearing for the foundations for a 230 m long building. The use of a reaction beam-soil anchor system for compression load tests is discussed. The results of static load tests to determine pile capacity are compared with those obtained by the Pile Driving Analyzer and by theory. Unusual high temporary compressions were observed by field control staff. Proof testing was necessary to determine the need for restriking of some piles in which rise had occurred.

Jan 1, 2010

By Steve Davidow, Ashely E. Evans, Peter M. Kandaris

"Annually thousands of deep foundations are constructed across North America supporting high voltage transmission line structures. However, a recent state of the practice survey by the Deep Foundation Institutes’ Electric Power Systems Foundation Working Group discovered that the electric power utility industry lacks consistent foundation design guidelines. The survey identified a wide variability in design assumptions, a minimal understanding of risk based analysis, and a need to standardize design methodologies. This paper summarizes the state of practice in electric system foundation design and proposes a framework for risk-based foundation design by accounting for uncertainty from both loads and resistances. Loads derived from electric system codes do not necessarily provide a compatible level of reliability for the design of foundations, as they are a mixture of probabilistic and deterministic values. Load uncertainty is derived from variability in weather conditions, structural models and material properties, typically accounted for by code derived overload factors. Resistance uncertainty arises from variability in natural soil properties, resistance models, subsurface construction techniques, material sampling methods, and limited observations. A consistent methodology is offered relating nominal resistance capacity (strength) to structure loads and service state criteria. Discussion also includes the need for risk-based assessments to account for non-structure load influences (fluvial loads, scour ground loss, liquefaction, etc.).INTRODUCTIONNearly 40 years ago the Electric Power Research Institute (EPRI) embarked on a major research effort to optimize reliability and economics of transmission line foundation design. Strategies focused on improvements in design models, site characterization, exploration strategies and testing to reduce uncertainty and variance in analysis. Transmission line engineers realized that safety and reliability advancements in design based on probabilistic approaches, with a focus on the unique nature of transmission line, could better control risk and cost.Some transmission line professionals took full advantage of these advancements, particularly where research led to improved software and models. Yet, even after two decades of extensive research, by 1995 the industry still had made little progress in changing design habits. The majority of designers were still characterizing sites via deterministic methods, using loads that may or may not relate to a consistent probability of occurrence, and applying a traditional global factor of safety approach (Phoon, et al. 1995). The following two decades have seen even greater developments in software and reliability-based analysis methods, but old habits seem to die hard as recent surveys show less than half of design professional quantitatively assess risk in their design process."

Jan 1, 2017

By Babak Mamaqani, Pirooz Barar

The Heights project was located at Fashion Valley North, San Diego, CA. The scope of the project was to replace two existing commercial buildings with a large 7-story multi-family residential building. There was an existing 1:1 slope on the north side of the site. A permanent soil nail wall, 1,000 linear ft long, with a maximum height of 100 ft, was needed to replace the 1:1 slope at the north side of the project to accommodate the development. Previously there was a design for the permanent soil nail wall which required up to 115 ft long soil nails with large diameter rebars and 13 in. thick permanent facing. PB&A was engaged by the owner to conduct soil nail design optimization and value engineering to reduce construction costs and improve scheduling. First, the SnailPlus program was used to check the stability under static and seismic conditions and to design soil nail lengths and sizes. Then, soil nail head forces were calculated to design the permanent facing using FHWA recommended procedure. Another challenge of the project was to evaluate the interaction between a future San Diego Gas and Electric (SDG&E) tower and the soil nail wall. Finite element analyses were conducted with the PLAXIS program to ensure the deflection of the future tower would be within the acceptable range. The soil nail design optimization helped the owner to save approximately $800,000 in construction cost and improved construction scheduling.

Sep 8, 2021

By Howard A. Perko, Melinda J. Hummel

"Hydraulically jacked piles, herein referred to as jacked piles, are commonly used for underpinning existing structures to arrest settlement or augment an existing foundation for higher loads. They consist of steel pipe segments coupled together and jacked into the ground using a hydraulic ram. Pipe sections can vary in size from 3"" diameter to 18"" diameter or larger. Jacking resistance is typically provided by dead loads of existing structures. This type of piling system has been utilized for foundation underpinning, repair, and augmentation for more than 120 years, yet little has been published on the capacity, installation standards, and reliability of these systems. Pile load tests from a number of projects are presented and analysed. The data show that previous methods of jacked pile capacity and depth prediction are crude at best. Empirical relationships between capacity, depth, soil type, and standard penetration resistance blow count contain a high degree of scatter. Scatter in the data indicate capacity prediction for jacked piles needs further research and refinement.INTRODUCTIONPush pier, resistance pile, steel pier, and jacked pile are some of the names often applied to hydraulically jacked piles used for underpinning. The term ‘jacked pile’ is more common in building codes and will be used herein. Although jacked piles can be installed for new construction, this paper is focused on piles used for support of existing structures.Jacked piles consist of short segments of pipe or structural steel tube that are coupled together and forced into the ground using a hydraulic ram fastened to or beneath a footing, stem wall, or grade beam of an existing structure. In this way, the weight of the structure provides the resistance necessary to force the pile into the ground. A factor of safety can be achieved in design by redundancy, which is consecutively installing more than one jacked pile to support the same portion of foundation. Installing jacked piles consecutively using the same dead load and then releasing the load after each pile installation allows one to continue adding piles to the same general area until a total aggregate capacity is achieved to account for anticipated dead plus live loads and a desired factor of safety for that area.An engineering schematic of an example jacked pile connected to a footing foundation is shown in Figure 1. Modern jacked piles typically incorporate a steel bracket. There are many sizes and styles of brackets available. Some categories include plate brackets that bolt to the outside of an existing foundation wall, wide and narrow angle brackets that extend under existing footings, pin brackets for attachment to structural steel, and reverse angle brackets for attachment to footing and wall. Table 1 lists example brackets and their benefits."

Jan 1, 2017

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 Javankhoshdel Yacoub

Piles are often used to reinforce slopes as they increase the available restoring force when calculating the factor of safety against sliding. In this paper, a 3D model of a slope containing multiple modes of failure is reinforced using pile elements. The results of the 3D Limit Equilibrium analysis containing piles are obtained using a newly introduced coupled approach which combines the results of finite element analysis (to obtain the displacement of soil along the pile) with the traditional limit equilibrium iterative formulation. The multiple modes of failure are obtained using the novel Multi-Modal Optimization (MMO) metaheuristic method which adapts the Particle Swarm Optimization (PSO) method to search for multiple local minima in a single slope model.

Oct 1, 2022

By Albert Neumann, Franz-Werner Gerressen, Giancarlo Santarelli

"Diaphragm walls are known as underground structural elements commonly used for retention systems and permanent foundation walls or elements. In addition they are also quite often used as deep groundwater barriers, named Cut-Off-Walls (COW). Due to the requirements of each particular job site, e.g. the need for carrying high loads or as seepage barriers, there is an increasing industry demand for efficiently cutting into rock. Besides the removal of boulders, cutting through rock, is always the most difficult part of the excavation process of a diaphragm wall or COW.There are a number of influencing factors which have an impact on the rock cutting performance. Besides the influence of the rock characteristics itself, which is not always the same, there are other factors related to equipment, tooling as well as the operating staff. In addition to RQD, the most commonly available rock property found in geotechnical reports is the Unconfined Compressive Strength (UCS) value. There are however some other related properties, such as weathering, bedding, inclination, abrasiveness, etc.,which can have a major impact on the achievable cutting performance. This paper will discuss the various parameters, and how they can be considered for performance estimation. Based on experiences gained on over 100 projects, a performance estimation chart was developed to allow for a better approach to these kinds of projects. This paper also explains the general installation process in as well as some specific features related to specific site conditions. In addition, some job site references will give more detailed information about such type of site conditions and how to deal with them.Keywords: Diaphragm wall, Cut-Off-Wall, Trench Cutter, RockINTRODUCTIONDiaphragm walls are known as underground structural elements commonly used as retention systems for excavation pits, shafts, permanent foundation walls and load bearing elements.It can be anticipated that, with the increasing trend of utilizing more and more underground space to accommodate environmental considerations and urban/suburban development, there will be an increasing requirement for diaphragm wall usage in even more difficult conditions.In addition diaphragm walls can also be used as deep groundwater barriers (Cut-Off-Walls). This market has demonstrated that the demand for these types of walls is reaching ever more difficult soil conditions and greater depths which are surpassing the current industry standards. The trench cutter is the most important tool for performing this type of work."

Jan 1, 2016

By Hubert Law, Dan A. Brown, Kyle M. Rollins

"Soil mixing and jet grouting provide a means to significantly increase the lateral resistance of pile group foundations with relatively little investment of time, effort, and expense compared to the cost for additional piles necessary to produce the same increased resistance. Comparative field testing conducted on full-scale pile groups before and after treatment of small soil volumes showed significant improvement in lateral resistance. The lateral resistance of the pile group increased by 60% due to soil mixing and by 180% due to jet grouting. To provide additional understanding regarding the influence of the soil mix strength, depth of improvement and width of improvement, a series of parametric studies were performed using a 3D finite element model. This set of “virtual load tests” was then combined with the results from the actual field tests to help develop a simplified model to account for observed behavior. In general, the testing and analysis indicate the pile group and the surrounding improved soil block generally act as an equivalent “super pile”. The passive force, side shear and base shear on the improved soil surrounding the pile group itself increased lateral resistance. This increase in resistance from the soil block can be added to the lateral resistance of the pile group.INTRODUCTIONThe lateral resistance of pile groups is often critical to the design of bridges and high-rise structures subject to seismic, wind, wave and landslide forces. Typically, when analyses indicate that the lateral resistance of a foundation is inadequate, additional piles, drilled shafts or micro-piles are added to increase the lateral resistance. Furthermore, an expanded pile cap or connecting beam is often required to structurally connect the new piles to the existing pile group. While this approach provides the required lateral resistance, it may also be relatively expensive and time consuming. An alternative approach is to use soil improvement techniques to increase the strength and stiffness of the surrounding soil and thereby increase the lateral resistance of the pile group. The improved zone could potentially be relatively shallow because the lateral resistance of piles is typically transferred within 5 to 10 pile diameters. For example, the soil around the periphery of the foundation could be relatively easily improved for an existing foundation as illustrated in Fig. 1(a) using a variety of soil improvement techniques. Alternatively, the soil under the foundation could be improved for a new foundation or even for an existing foundation with a technique such as jet grouting (see Fig. 1(b)). Improving the soil under the foundation would have the potential for producing greater increases in lateral resistance because the improvement would reach interior piles. In addition, the process of creating a cemented “soilcrete” zone around pile foundations could potentially produce a zone which would behave like a reinforced “superpile” with increased structural stiffness."

Jan 1, 2015

By Masaru Sakakibara, Ngo Tuan Anh, Mitsuo Nozu

"In the southern region of Vietnam and the southern United States, numbers of Deep Mixing (DM) columns have been installed to increase the stability of slopes and mitigate ground settlement. However, in some cases, there were some quality problems for in-situ cement mixing such as inclusion of unmixed lumps. According to the investigations by the X-ray diffraction analyses, electrical conductivity (EC) test, and careful observations of in-situ mixing quality, it has been observed that the existence of expansive soil and its high EC value cause the insufficient in-situ mixing. The countermeasures to address these problems have been taken.INTRODUCTIONIn South Vietnam, under the guidance of numbers of references and standards (Miki, 1998, JGS, 2000, Kitazume et.al., 2001, BS 2005), Deep Mixing (DM) has been used in recent years for soft clay improvement to increase the stability of slopes and to reduce consolidation settlement (Nozu 2005, Tung et.al., 2009, S. T. G. Peng et.al, 2009). However, at the initial phase of the DM operation, the authors have encountered some unusual phenomena such as (1) lower strength and inclusion of unmixed lumps (Figure 1), (2) less amount of up-heaved soil, and (3) sticking of large lumps of clay to the mixing blades. In regard to the above (3), Photo 1 shows one of the countermeasures against the sticking. By means of the placement of additional plates, the stuck clay has been reduced significantly.Subsequently, we have noticed that the quality of DM columns has not been so good, which meant that there have been some unmixed lumps in the column despite high cement dosage such as more than 300kg/m3. The authors also have encountered the similar incidents in Vietnam and United States during the deep soil mixing work. For example, Photo 2 is the core samples taken from the DM test column in northern Vietnam adopting cement injection during penetration (CIDP) procedure. To solve this problem, various tests and investigations have been performed so far (Nozu 2010, 2012)."

Jan 1, 2015

By Wang Huichang

A tentative mathod for predicting load-settlement relationship and bearing capacity of single piles based directly on the results measured by cone penetrometer with local friction sleeve is presented. It is possible that the load-settlement curves can be constructed by means of CPT and the problem of both the bearing capacity and the settlement behaviour of single piles can be considered jointly. The proposed load-transfer functions are continuous, positive monotonic and nonlinear. a concept of weight mean point resistance 2D above and 4D underneath the pile base to determine the unit ultimate base resistance of piles is presented. The predicted results of seven jacked piles in loess are in good agreement with the load test data.

Jan 1, 1991

By Karl A. Higgins, Michael D. Venezia

The South Capitol Street Corridor Project is one of the District Department of Transportation’s (DDOT) largest projects, and is currently under construction. This case study will focus on the design of the foundation piles for the main spans of the iconic Frederick Douglass Memorial (FDM) Bridge, and will include a discussion of the foundation design evolution from an originally designed alternative foundation system (i.e. coffer dams and drilled shafts), to the current use of driven Large Diameter Open End Pipe (LDOEP) Piles. The paper will provide a discussion of the design methodology used during preliminary engineering and final design, and will highlight insight gained from the extensive load testing program completed to date. The load testing program consists of a combination of high strain dynamic testing (PDA), as well as Statnamic Load Testing on select sacrificial, pre-production test piles. Specifically, data gathered during the nearly-completed load testing program suggests the development of significant internal shaft frictional resistance within the tested LDOEP Piles. This paper will also discuss limitations of currently accepted industry design methods for predicting the capacity of LDOEP piles, a subject that is also currently being researched by FHWA. The data from this test pile program will help design assumptions for future projects. INTRODUCTION The Frederick Douglass Memorial (FDM) Bridge carries South Capitol Street across the Anacostia River in Southeast/Southwest, Washington, DC, and is owned and maintained by the District Department of Transportation (DDOT). The existing FDM Bridge is nearly 70 years old, serves as a major artery into the city, and has been classified as functionally obsolete. As a result of the condition, age and limitations of the existing bridge structure, DDOT deemed it necessary for complete replacement of the bridge. The replacement project consists of the construction of a new bridge traversing the Anacostia River, as well as the reconfiguration of the Suitland Parkway and I-295 interchanges located at the eastern terminus of the FDM Bridge. Final design and construction services for the replacement project were procured by DDOT through a Design-Build contract. This paper will focus on the driven Large Diameter Open End Pipe (LDOEP) Piles used for support of the main span of the new FDM Bridge which is currently under construction. Discussion regarding the LDOEP Pile design methodology has been included, along with commentary regarding currently available industry guidance related to design and construction of LDOEP Piles. Much insight has been gained during the mostly-completed and extensive load testing program which consists of a combination of high strain dynamic testing (PDA), as well as Statnamic Load Testing on select sacrificial, pre- production test piles. Specifically, data gathered during the mostly-completed load testing program suggests the development of significant internal shaft frictional resistance within the tested LDOEP Piles.

Jan 1, 2019