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By Lori A. Simpson

A high-rise building, consisting of two tower structures occupying the entire site, is in construction in San Francisco. The North Tower will consist of 12 and 35 stories above a one-level basement. The South Tower will consist of 9 and 22 stories over one partially below-grade level of common space; a portion of the South Tower will have a three-level basement. The towers will be supported on mat foundations bearing on native very dense sand in the footprint of the three-level basement and on ground improved with soil-cement mixed (SCM) panels that extend through loose sand and marsh deposits into very dense sand. Shoring systems for the basement excavations include cantilevered and tied-back soldier-beam-and-lagging systems and SCM cutoff walls. Subsurface conditions include loose fill and Dune Sand and loose and soft marsh deposits overlying very dense sand of the Colma formation. Groundwater is approximately 15 to 22 feet deep; the three-level basement extends below groundwater. The site is on Market Street in San Francisco, with SF Municipal Railway (MUNI) and Bay Area Rapid Transit (BART) tunnels running below Market Street approximately 45 and 36 feet north of the site, respectively. Both tunnels are 16.5 feet in diameter. The top of MUNI and BART tunnels are 25 feet and 63.5 feet below street grade, respectively. BART has stringent requirements regarding construction adjacent to their facilities, including disallowing adding pressure to their tunnel, lowering groundwater by more than two feet, and vibrations from construction activities. Design of the shoring and the foundations within the BART zone of influence were subject to their design requirements. The project was also subject to a peer review, as required by the San Francisco Department of Building Inspection. We used FLAC to evaluate stresses at the BART and MUNI tunnels and on the SCM panels. This paper will present the mitigations needed to address seismic hazards and BART restrictions and to provide adequate foundation support for a tall building with high seismic loads.

By James L. Christensen, Gregory Sanchez, Michael P. Walker

The Fogg Museum expansion project required excavation and construction in a congested urban area in Cambridge, Massachusetts. A soldier pile tremie concrete (SPTC) wall provided the support of excavation and now serves as the permanent basement wall of the new expansion of the museum. The existing Fogg museum had a single basement level. The new expansion has a two-level basement for new exhibit space and an amphitheater. The east side of the site is about 20 feet above the basement level of the existing Fogg structure which resulted in a significant unbalanced load that needed to be resolved without damaging the original Fogg structure. The SPTC wall was supported with a combination of tiebacks and internal bracing. The final depth of the excavation was about 40 feet below street level. Strict movement control was imposed because the existing museum contained an Italian Renaissance-style courtyard. The southeast corner of the SPTC wall had to accommodate underpinning of an historic concrete ramp which was ultimately incorporated into the expansion. Challenges during construction included excavating the SPTC wall panels up to 12 feet into argillite bedrock which had occasional diabase dikes and sills. The following topics are discussed in more detail after a general project.

Jan 1, 2015

By John L. White

The vibro driver/extractor is a machine that grips to a pile and vibrates it up and down. When the vibrating pile is lowered into the ground, all soil around the pile begins to vibrate. A vibrating pile breaks the friction between the pile and the soil, thus allowing it to penetrate the ground. A vibro is usually operated by hoisting it into the air with a crane and then placing it onto the pile. The vibro has hydraulic gripping jaws that are controlled from the ground. Once the operator has successfully lowered the vibro onto the pile, the jaws are closed and locked onto the pile and operations can begin. Please see the drawing below: [ ]

Jan 1, 1990

By Robert B. Bittner

The Sutong Bridge across the lower Yangtze River in China will have, when completed, the longest span (1,088 m) and the highest towers (306 m) of any cable stayed span in the world. The foundations for this record setting span will also be record setting. They are located in water depths exceeding 30 m with maximum flows exceeding 3 m/sec. The soil at the site of the main pylons consists of layers of silty sands and silty clays extending to bed rock at 270 m below river elevation. This paper describes the innovative methods used by the team of foundation designers and constructors to support this record setting bridge at this very challenging site. This paper covers three specific topics related to the foundations of the Sutong Bridge: ? Design and construction of the 131 drilled shaft (2.8/2.5 m diameter and 114/117 m long) under each of the two main pylons, including the post-grouting of all drilled shaft tips. ? Design and construction of the scour protection for the two main pylons, ? Construction methods used to construct the waterline pile caps (113.8 m by 48.1 m by 13.3 m deep) under each pylon.

Jan 1, 2013

By Shigenori Horikawa, Nobutaka Tanaka, Toshiro Hara, Kengo Yamamoto

"The CDM-LODIC method(Low Displacement and Control method), a modified the CDM(Cement Deep Mixing) method, reduces the ground displacement through the removal of in-situ soil equivalent to the amount of slurry injection using the continuous auger flight attached on the shaft above the conventional the CDM mixing tool. The reduction of ground displacement minimizes the impact on adjacent buildings and other infrastructures. Since the development of the CDM-LODIC in 1985, this method has been used for more than 900 projects with total volume of improved soils exceeding 5.3 million yd3 (7 million m3). The ground displacement that could be caused by deep soil mixing is controlled by balancing the volume of discharged soil and the volume of slurry injected for soil mixing. This paper presents the ground improvement work for the Sanriku Coast Expressway Project using the CDM-LODIC method to 1) control the ground displacement during ground improvement to minimize the impact to existing buildings and facilities and 2) utilize low height CDM-LODIC equipment to avoid potential damage to critical facilities in the vicinity of ground improvement area and avoid interference on the normal operation of the Ishinomaki Red Cross Hospital.INTRODUCTIONSanriku Coast Expressway is a reconstructed highway, which is part of an early restoration program to recover from the Eastern Japan Earthquake of March 11, 2011. This highway extends 223 mile (359 km) and connects the Pacific Coast regions of three prefecture of North Eastern Japan as shown in Figure 1. Along a section between Yamoto - Ishinomaki road, the highway was expanded from two lanes to four lanes to mitigate traffic congestion for the adjacent city center and hospital and to serve as an efficient transportation route for emergency or disaster relief needs as shown in Figure 2. Deep mixing ground improvement with an area replacement ratio of 50% was designed to provide settlement control under the new fill embankment of the expanded highway as shown in Figure 3. The original CDM treatment layout using 5.2ft (1.6 m) diameter columns is shown in Figure 4."

Jan 1, 2015

By Mark Koelling

This paper presents a case history of a ground improvement program conducted in a soft soil environment and seismically active region in the northwest corner of Washington State near the Canadian border. The program was performed over several years, and provided adequate soil bearing conditions for the construction of several structures. Completed development includes separate construction of four adjacent structures, each with unique total and differential settlement requirements and built at approximate two year intervals. Site soils consist of 45 feet of loose saturated sand and silt overlying 70 feet of very soft to stiff (N60 = 0 to 7) normally consolidated clay. Adding to the complexity of the site is the owner?s requirement that all existing structures remain open and in service during construction of each subsequent structure. The paper presents the site geotechnical information and the foundation design issues. Details of a combination of ground improvement methods is presented, including stone columns, wick drains, a preload surcharge, and staged construction to provide soil support for shallow foundation construction of all structures at this site. The soil test results and settlement observations are presented along with QA/QC measures. Lastly, a brief method sustainability comment will be made.

Jan 1, 2010

By Oladayo O. Komolafe and Majid Ghayoomi

p-y curves have been used over the years to determine the lateral resistance of piles. This method is popular among practicing engineers due to its simplicity and its ability to determine the slope, displacement, shear force, and bending moment for various depths along the pile. The ultimate lateral load resistance is a key component of p-y curve formulation. The p-y curve formulation by Reese et al. (1974) does not consider the effects of soil’s degree of saturation on theoretical ultimate lateral resistance of the failure wedge. This limits an accurate assessment of the lateral soil resistance near the ground surface and the consequent p-y curves. This paper extends the existing approach for determining the failure wedge in unsaturated cohesionless soils with suction dependency, especially for the depths that are above the water table within the wedge. The modification to the failure wedge analysis was made by considering the variation of the degree of saturation which affects effective stress and lateral earth pressure. Through a set of parametric analyses, the impact of incorporating principles of unsaturated soil mechanics in the estimation of theoretical ultimate lateral resistance is examined, and its implications on lateral pile response are discussed.

Sep 8, 2021

By Sherrill Gardner

Vibratory drivers have been used since the 1930s to drive and extract piles. Vibratory pile drivers have the capability of significantly decreasing pile installation time, especially in granular type soils. However, they have not been widely accepted because of the uncertainty in estimating the bearing capacity of the driven pile. When driving bearing piles, the industry standard method for obtaining load carrying capacity of a pile installed with a vibratory driver is to redrive with an impact hammer. The advantage of improved productivity is lost with the redrive procedure. Currently, there is no other method to predict the capacity of these bearing piles installed with a vibratory driver. The Naval Civil Engineering Laboratory (NCEL) is making progress towards being able to estimate the bearing capacity of these piles. This paper describes field testing and corresponding analytical modeling of the vibratory driver-pile-soil system. The following sections describe the development of the numerical model and techniques for collecting field data. A discussion of the prediction of the pile driving process based on field test data is followed by suggestions as to the additional work that should be done to further verify the model to a point where it can be used with confidence.

Jan 1, 1987

By Sherif Elfass, Gary Norris

Bi-directional load testing of drilled shafts has been widely adopted as a means to evaluate their load carrying capacity. However, in order to reach failure, most of these tests are carried out on sacrificial shafts using expensive sacrificial elements such as hydraulic jacks. A proposed low-cost bi-directional testing technique is discussed. It mechanically loads the end bearing soil below a drilled shaft, against its side shear resistance. The technique was originally established as an alternative to post-grouting to reliably account for the forfeited end bearing resistance. However, since it loads the shaft in a manner similar to conventional bi-directional tests, it can be used to not only load test sacrificial shafts, but production shafts as well. Furthermore, unlike conventional bi-directional load tests, the load is applied through surface jacks. These jacks, along with other load test components, are movable and can be reused to load test all the shafts of the project thus presenting an economic benefit. The concept of this technique has received favorable feedback from a few consulted departments of transportation, and while promising, has not been field tested to date. A U.S. patent was issued for the tip loading module and the loading technique described.

Sep 8, 2021

By Pier Luigi Iovino

As Technical Director of the Naples, Italy based Fondedile, a geotechnical construction firm specializing in static restoration of structures, Fernando Lizzi, Ing., devoted over 30 years to the pursuit and advancement of static restoration and subsoil strengthening. Seismic events, construction of new structures on polluted and/or unstable soils in urban areas, and a need to carefully preserve and restore delicate, war-damaged historical structures, manifested the need for underpinning projects. Traditional construction methods and approaches, such as underpinning with additional foundation masonry, were not suitable and would have further jeopardized the stability of the structures. The introduction of the palo radice (root pile) revolutionized the field of underpinning. At the time of the first application of micropiles, the industry standard was driven piles. The drilled micropile was conceived and first implemented in the early 1950s, as an innovative means to underpin sensitive, historic structures and structures in urban areas. Specifically, the new construction technique was conceived as a less expensive alternative, designed to accept structural loads, be installed in limited access areas, in varied working and sub-surface conditions, which did not involve changing soil characteristics, and had minimal disturbance to the structure being underpinned, or to adjacent structures.

Jan 1, 2003

By David White

When finished (projected completion in 2016) the Hong Kong-Zhuhai-Macau Bridge Project will comprise three cable-stayed span bridges and a 4.15 mile immersed tube tunnel - linking Hong Kong to Macau and the mainland Chinese city of Zhuhai. The design included two artificial Islands to serve as the transition structures for the tunnel to bridges, entailing a massive seaborne land reclamation project, and the use of thousands of sheet piles, and man-hours. The challenges of driving individual steel sheet in 100? of water are well known, let alone in the open waters of the South China Sea. In 2010 a joint effort between American Piledriving Equipment (APE) and Allnamics Pile Testing Experts convinced the Chinese contractor First Harbor Marine Group China that a massive multi-vibro hammer can be used to drive 130? long, 72? diameter steel pipe piles weighing 662 US tons each into the sea bed of the South China Sea for the Hong Kong - Zhuhai - Macau bridge artificial islands. Combining APE?s hammer design, production and operation know-how with the pile driving simulation and installation know-how of Allnamics made it possible to show the feasibility of driving these gigantic piles into bottom of the sea to the required depth.

By Alan Quiroga

Nestled between Meridian Park and Howard University in the heart of Washington, D.C., the historic block between 14th, V and W streets North- west featured several original struc- tures, many of them dating to the 1800s. During its rich history, this square block has been home to a variety of different organizations including automobile showrooms and repair businesses, a parking garage, various industrial warehouses, and, in recent years, the headquarters of the renowned D.C. nonprofit Martha's Table. The revitalization of the buildings in this block also known as the Collection 14 project involved the transformation of aging and historical structures into a new multi-use development. The redevelopment project was distinguished by the retention of period street-facing building facades (to the extent possible) to preserve the character and culture of the historic neighborhood while revitalizing the block with some modern construction elements. The complexity of the project and difficult subsurface conditions required specialized and extensive sheeting, shoring and underpinning work to be performed. This project had many parties involved, including: • • • • Owner: Madison Investments Owner's representative: Compass Design & Development General contractor: McCullough Construction Civil engineer: Vika Capitol Structural engineer: Ehlert Bryan Architect: Perkins Eastman DC Geotechnical engineer: GEI Consultants Sheeting and shoring contractor: Steele Foundation

Aug 1, 2023

By David C. Kraft

Atlas Systems, Inc. (ASI) resistance type piers were used to underpin a 100 year old historic structure at Fort Monroe, Virginia. This 3-story structure with basement was underpinned with 155 steel tubular push piers (4" OD) that were hydraulically installed to depths ranging between 90 and 110 ft. and to installing forces in excess of 60,000 lb. Project requirements included lowering the basement floor by 1-1/2 ft. and constructing new footings and adding stem walls to connect to the existing masonry walls. Additionally, the underpinning piers were temporary which required the development of a decoupling system to permit the transfer of the building loads from the underpinning piers to the new footings. The structural loads at the foundation level required a c. to c. pier spacing of 3.75 ft. in order to meet project requirements of a minimum Factor of Safety of 3.0 on the pier load capacity. Project requirements included a load test on the selected underpinning pier (ASI - AP2 4000.219) in order to establish installation depths for seating the piers to 60,000 lb. The project was successful in supporting the full load of the structure during the construction phase. Considerable savings in time and cost were achieved as well as avoiding any vibrations or noise during installation of the piers.

Jan 1, 2002

By Ahmed H. Bukhary, Naser A. Al-Shayea

The objective is to assess the overconservatism in the parameters used for designing offshore piles. Methodology includes analysis of shaft friction data obtained from more than five different locations in the Arabian Gulf, consisting of 40 piles to depths up to 86 m. Reports were collected for both the dynamic pile monitoring system (DMS) and their corresponding geotechnical reports based on the American Petroleum Institute (API). The values of shaft capacity for the sand layers were analysed by comparing those based on API to the corresponding DMS values. Results of the comparison of the data from these reports showed that the pile design parameters obtained using API guidelines is generally smaller than that measured by DMS. The difference is presented in terms of an overconservative factor (OCF) which is adjusted based on statistical nonparametric test performed on the two data sets. The adjusted OCF were found to be 1.79 and 2.00 for carbonate sand at (loose to medium dense) and (dense to very dense) conditions, respectively. The corresponding values for silica sand were only 1.2 and 1.06. In conclusion, based on the evaluation conducted for data from these reports, the API shaft friction is overconservative for carbonate sand. The API shaft friction for piles in sand can be increased by multiplying it by the adjusted OCF.

By Ilhan Chang, Ernest Nsabimana, Kiseok Kwak, Juhyung Lee, Young-Hoon Jung

"Numerical analyses were performed to analyze the behavior of two different type of suction piles (mono type and group type) under various soil layer conditions (uniform silty clay layer, uniform silty sand layer, and two-layer deposit consisting of clay and sand layers) and lateral loading locations (top, middle, and bottom of the suction pile). According to the results, mono suction pile shows maximum resistance when load is applied on its middle, regardless of the soil layer conditions, while group suction piles varies significantly according to the allowance on head rotation. When head rotation is allowed, the behavior of group type piles become similar to the behavior of mono suction pile. Whereas, when rotation is prevented, resistance is maximized when load is applied on the top head. Moreover, group suction piles show higher efficiency regardless of the ground condition and geological stratum. For further advances, concrete block on the top of group suction piles are suggested as an effective alternative method to prevent partial rotation and maximize ground resistance for group suction piles.IntroductionWith the development of offshore technology, applications and real site installations of suction piles are increasing significantly nowadays. They are generally used as mooring anchors in various floating structures, marine platforms, and offshore wind turbines. According to its convenience in installation and removal, suction type foundations are becoming good alternatives for deep ocean support systems. The bearing capacity is similar to the bearing behavior of ordinary offshore structures (piles or drilled shafts). The most common use of suction caissons is anchors for catenary mooring lines, where the chain angle at the mudline is close to zero (Randolph, 2002; Sharma, 2004).Recently, it is reported that a huge isolated single suction pile can be replaced by a group of moderatesized suction piles (Randolph et al. 2004). A single monopile is easy to be produced and installed in site. It is expected that monopile foundation is not applicable for deep depths because it has a limitation on penetration according to its huge side skin area (i.e. friction). Moreover, stiffness requirements sometimes render thicker pile wall conditions which are impractical to be produced."

Jan 1, 2017

"Every year during the Transportation Research Board (TRB) Annual Meeting in Washington D.C., the Federal Highway Administration (FHWA) National Geotechnical Team (NGT) takes time to talk about what we are doing in research, training development and policy support. At times, I have jokingly referred to it as the State of the Program Address, but we do see it as an important opportunity to update our transportation partners on priorities and needs for the program.This update is really a snapshot of the program during the previous year, with a look at projects that are currently active. Activities undertaken by the NGT are funded from multiyear roadmaps maintained by the FHWA program and research offices, and reflect trends and opportunities affecting and influencing transportation geotechnics now and in the future. The roadmaps identify activities in research, development, guidance, technology transfer and training that will be accomplished by the NGT through and beyond FY 2020 in eight broadly-defined focus areas: • Extreme events, geohazards and sustainable geotechnics• Performance management• Reliability-based design and construction• Advanced geotechnical modeling• Alternative delivery methods• Design and construction optimization• Site characterization• Quality assuranceThe process to identify focus areas and to develop activities that will be addressed by the NGT is guided and informed through input from the FHWA NGT members, and considers feedback and input from State Departments of Transportation (DOTs), FHWA Division offices, industry and academia. This process is revisited annually to review not only the activities that are currently funded, or will be funded, but also to review the relevance of the focus areas with respect to the future needs of the FHWA, State DOTs and the transportation community.In 2016, the NGT was successful in delivering several products that will advance the state of the practice and that better support policy. Products developed included research reports, design and construction guidance, and training courses. In 2017, the research and program offices will continue to work on projects that fit within our prioritized plan and that positively impact the geotechnical community as a whole. A listing of recently completed and currently active projects is provided below."

Jan 1, 2017

By Hamed Ardalan, Mohamed Ashour

"CHAPTER 1INTRODUCTIONThe use of piles to stabilize active landslides or to prevent instability in currently stable slopes has become one of the most important innovative slope reinforcement techniques over the last few decades. Piles have been used successfully in many situations in order to stabilize slopes or to improve slope stability, and numerous methods have been developed for the analysis of piled slopes (Ito et al., 1981; Poulos, 1995; Chen and Poulos, 1997; Zeng and Liang, 2002; Won et al., 2005).The piles used in slope stabilization are usually subjected to lateral force through horizontal movements of the surrounding soil; hence they are considered to be passive piles. The interaction behavior between the piles and the soil is a complicated phenomenon due to its 3-dimensional nature and can be influenced by many factors, such as the characteristics of deformation and the strength parameters of both the pile and the soil. The interaction among piles installed in a slope is complex and depends on the pile and soil strength and stiffness properties, the length of the pile that is embedded in unstable (sliding) and stable soil layers, and the center-to-center pile spacing (S) in a row. Furthermore, the earth pressures applied to the piles are highly dependent upon the relative movement of the soil and the piles."

Jan 1, 2013

By Wolfgang G. Brunner

In the far north of Uttar Pradesh Province in the Indian Himalayas, the 280 MW Dhauliganga hydroelectric power plant is under construction by National Hydroelectric Power Corporation (NHPC), a state- owned enterprise, and a joint venture of Kajima Corporation of Tokyo and Daewoo Corporation of Seoul. This project sets out to develop the lower section of the mountain cascade of the Dhauliganga River, a tributary of the Sarda River, with a 311 m gross head. The 1360 km2 mountainous catchment area is bounded in the north- east by the Chinese border and in the south- east by the Nepalese border. The dam project is located in a remote area north of the principal town of Darchula of the upper Sarda valley, which is one of the seismically most active regions of India. The 56 m high rock fill dam, which will be the first of its kind in India, is faced with concrete and has a 1 m thick, at its crown 270 m long and over 70 m deep cut- off wall of plastic concrete below its toe. The cut- off wall, with a total area of 7500 m2, is constructed by a combination of Bauer hydraulic grabs, assisted by chisels and a Bauer BC 40 cutter which enables the overlapping joint system to be installed, guarantees optimum verticality and enables the cut- off to be keyed into the bedrock formation.

Jan 1, 2004

By Gerry Houlahan

The east span of the 3.5 km long SF-Oakland Bay Bridge is supported by different types of foundations along its span. Starting from the west, its first 460 m section comprising twin concrete box-girders is supported by sands and rock on Yerba Buena Island. A 620 m long steel suspension span then bridges a 25 m deep channel that is formed in sediments overlying rock. Twin concrete box girder structures, each 2.4 km long, complete the stretch over the remainder of San Francisco Bay to the engineered earth fill landing at its east end. For most of its length, the Skyway bridges water 3 to 10 m deep over soft surficial Young Bay Mud. The foundation types include spread footings with hold-downs, steel and concrete piles that are set in drilled rock sockets up to 3 m in diameter and 2.5 m diameter steel tubular piles driven to penetrations of up to 100 m. The design and construction-related considerations are presented. The different foundation types, influences of the site geology and earthquake demands on the substructures are discussed. The seismic motions of the bridge superstructures and substructures, as well as the depth-varying soil motions, influenced the foundation design. Together with performance-based design criteria, including post-earthquake footing displacement limits, these seismic demands influenced various aspects of the foundation design, including the use of battered and vertical piles.

Jan 1, 2013

By H. Shiri

Iran's largest natural gas field is South Pars, geologically an extension of Qatar's 900-Tcf North Field. South Pars was first identified in 1988 and originally appraised at 128 Tcf in the early 1990s. This Field contains 38.6 % of the gas resources of Iran and is regarded as the largest offshore gas field in the world. Offshore geotechnical site investigations are one of the key activities of upstream fields operators to supply the EPC contractors with the required results for designing approaches of offshore complexes. In the mean time a lot of marine site investigations have been carried into execution within the phases of South Pars development. The authors are currently trying to create the fundamentals of investigating the small- and large-scale spatial variability of the South Pars Gas Field in Persian Gulf/ IRAN. Part of this investigation is the providing of an extensive data base of the offshore geotechnical properties of South Pars. Such a data base, will enable a model to be developed of the large-scale variability of these properties. In addition, this data set will provide a data whereby general trends to be established, as well as, providing relationships between geotechnical parameters and spatial parameters utilizing probabilistic and data mining methods like ANN (Artificial Neural Network) in Geotechnical Engineering.

Jan 1, 2006