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By Richard Guenther

As available space in urban centers becomes more scarce, builders and developers are increasingly turning to vacant, existing structures to meet cities' growing needs. The developers of City Ridge Roadside Development and North America Sekisui House (NASH) - - found a suitable site for their "urban village" at the former Fannie Mae headquarters complex on Wisconsin Ave. NW in Washington, D.C., which had been vacated in early 2018. The urban village will consist of eight new structures centered around the building that currently sits on the site. All told, the project will include 687 residential units, a 150-room hotel, over 150,000 sq ft (13,935 sq m) of retail space, and 62,000 sq ft (5,760 sq m) of office space. A below-grade parking structure will extend across most of the footprint. The Fannie Mae building, which was designed in the Colonial Revival style to mimic the Governor's Palace in Williamsburg, Virginia, was named a historical landmark following a request from the development team. The central portion of its existing masonry structure was built in 1956 on pile caps with small-diameter cast-in-place piles. Two wings, which were added in 1962, were built on belled caissons. There are three levels above grade and one below.

Feb 1, 2022

By Brian Metcalfe, Kord Wissmann, Gianni Martinez

The Middle East consists of vast deserts that reach temperatures up to 50°C (122°F), with some areas characterized by endless sand dunes. When project team members selected the location for a large new transportation project, little did they know that the site would be characterized by soft, nearly normally consolidated silt and clay extending below a thin sand crust. Searching for solutions, the design team elected to reinforce the sub­surface with rammed aggregate pier ground improvement elements and wanted verification that the method would stand the test of prolonged static loads. Because the concrete pave­ments would serve to spread the load, a "zone load test" was performed, consisting of applying a uniform bearing pressure of 150 kPa (22 Psi) over a 7.5 m (25 ft) square concrete footing. Unlike individual pier load tests, the zone test allowed the project engineers the opportunity to confirm design parameter values under large­loading area conditions, a situation not often available to most designers. This paper presents the results of the zone load test, which may be interpreted to better understand design parameter values, and is of particular significance because it adds a valuable contribution to the relatively few numbers of "group load tests" available in the literature for ground im­provement applications.

Feb 1, 2024

By Meeok Kim, Thornton Tomasetti, Seth Knihtila, Michael Oakland, Shawn Leary

The transformation of Seattle's historic KeyArena into the state-of-the-art Climate Pledge Arena, home to the NHL's Seattle Kraken, was no small feat. The $930-million renovation and expansion required the near-total demolition of the old structure and construction of an 800,000 sqf (74,000 m2), below grade venue while keeping its landmarked façade and roof intact. To do that, the project team had to come up with solutions for excavating 680,000 cu yd (520,000 m3) of soil to make way for the new 17,000-seat arena while working around the massive temporary shoring supporting the 44 million lb (20 million kg) roof all in time for the NHL's 2021-22 season.

Sep 1, 2023

By Fred Tarquinio, Giovanni Bonita, Lars Wagner

"A new embassy for the Peoples Republic of China is under construction in Washington, DC. The 475,000 square feet (44,125 m2) structure has five levels below ground and four above, making it the largest embassy in Washington DC. A vertical soil nail wall was used as the primary support of excavation system for the project. The soil nail wall was irregularly shaped, benched in areas, and up to 98 feet (29.9 m) in height. The soil nail and shotcrete system consisted of approximately 1,600 soil nails and 50,000 square feet (4,645 m2) of exposed shotcrete wall surface. Design and construction challenges included soft soil conditions, inside wall corners, underground utilities, seismic impacts from blasting, and logistical and political factors. Overall, wall movements were lower than expected, with maximum horizontal movement less than 0.25% of the total height of the excavation. INTRODUCTIONThe proposed Embassy of the Peoples Republic of China in Washington, DC, will consist of about 475,000 ft2 (44,125 m2) of building space and contain up to four fl oor levels above ground and fi ve levels of basement (Figure 1). When completed, the building will be the largest embassy in Washington, DC. The architect for the project, Pei Partnership Architects, along with the world-renowned architect I.M. Pei, made effi cient use of the site by inserting the building into the existing slope. Consequently, excavations reach heights up to 98 feet (29.9 m) on the southern side of the property and 42 feet (12.8 m) on the northern side.The soil nail and shotcrete system consisted of approximately 1,600 soil nails and 50,000 square feet (4,645 m2) of exposed shotcrete wall surface. The location of the building relative to the property line called for tight excavation requirements, including precise wall positions and shotcrete tolerances. Design and construction challenges included soft soil conditions, inside wall corners, arched walls, underground utilities, seismic impacts from blasting, and logistical and political factors."

Jan 1, 2007

By John P. Turner, Benjamin J. Turner

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

Jan 1, 2017

By Salim Mezazigh

Usually different methods for designing a single pile submitted to a lateral loading are available. They are based on theory of elasticity with the parameters E,v or subgrade reaction method using the p-y curves. The subgrade reaction methods are commonly used. They allow determining the efforts exerted along the piles and their corresponding displacements. Before any design the reaction curves P-y must be well defined for each foundation soil layer. These curves link the pile horizontal displacement y to the subgrade reaction of soil P. Different in situ tests such as the static penetrometer or the pressuremeter give a possibility to get the P-y curves in the case of a single pile installed in sand with an horizontal surface and statically laterally loaded. These ideal conditions are not always respected on the site around the pile if appear slopes, embankments, or buildings... The behaviour of such configurations of piles is more sophisticated due to the proximity ( slope, embankment, earthworks, buildings,..). A research program has been conducted to determine the influence of a slope on the P-y curves by centrifuge modelling. The centrifuge tests constitutes an experimental approach allowing parametric studies in respect with similitude laws in geotechnique. Before all, repeatable tests have demonstrated that the test conditions, the instrumentation equipment and the installation method for piles are well controlled. By this way, the obtained results from centrifuge tests can be transferred to the prototype i.e. the in situ piles. Many tests have been performed on piles in sand to determine the influence of a pile on the p-y curves. The main objective is to give for practice some coefficients to apply to p-y single pile curve to take into account the proximity slope effect. Here the experimental set up is described and in particular the proximity slope effect is discussed. Deduced subgrade reaction reduction factors are proposed for piles in sand under lateral loading.

Jan 1, 2002

By Md Kausar Anik, Ramin Motamed, Peiman Zogh

The earthquakes that occurred in New Zealand and Japan in 2010 and 2011 caused significant damage due to liquefaction. Engineers have adopted various ground improvement techniques to reduce the impact of liquefaction-induced damage, and one of these techniques is installing a sheet pile next to the foundation. However, the optimal depth into a non-liquefiable soil layer for having appropriate fixity of the bottom of the sheet pile remains unclear. To address this issue, a series of moderate-scale 1g shake table tests were conducted to evaluate the effective embedment depth of the sheet pile required to mitigate liquefaction-induced foundation settlement. A 1/5 scaled model consisting of three soil layers with varying densities, namely the crust, liquefiable, and dense layers, was prepared. A shallow foundation was placed over the crust layer and a sheet pile at a horizontal distance of 0.625 times the foundation length from the center of the foundation was inserted into the soil at various embedment depths using the press-in technique. The test results indicated that the foundation settlement could be reduced by 62% and 72% when the sheet pile was embedded to 50% and 100% of the dense layer thickness. It was recommended that the sheet pile be embedded at least 50% of the firm stratum thickness to achieve optimal performance.

Oct 31, 2023

By Brian Littlechild

Whilst there is much innovative work being undertaken in South East Asia in the space allowed in this paper we have settled on describing in more detail the work that has been done with shaft grouting of deep foundations and piles founded in rock both in end bearing and socket friction. The paper is necessarily in two parts. The first part is about the application of shaft grouting since its introduction to the region some eight years ago. It describes, for the first time, much of the detail of the different techniques used and the construction and the design benefits achieved with shaft grouting in five countries in the region. The second part outlines the enhancements achieved in the design of piles founded in rock and brings together the results of 10 years of test loading. This includes the load testing of 1.2m to 1.5m diameter piles to a maximum of 30MN on granite and a recent programme of tests on a wide range of strong rock types in Hong Kong. The ground conditions for these deep foundations vary widely, from sedimentary soils to in situ weathered granite and meta-sedimentary rocks. The construction techniques include barrettes constructed using mill techniques and bored piles formed under bentonite and water using both oscillators and rotators.

Jan 1, 2000

By Orestis Zarzouras, Amalia Giannakou, Jacob Chacko

"When designing structures in seismically active areas, foundations of critical structures are typically located away from known faults. Indeed many seismic codes prohibit construction in the immediate vicinity of seismically active faults establishing minimum setbacks from the faults. However, for long structures such as bridges, tunnels and pipelines, a fault maybe unavoidable, and fault rupture risk impossible to preclude. This paper presents a case study of a bridge foundation design that incorporates the consequences of fault deformations passing through the foundation. A series of site surveys were conducted to characterize the fault environment, and fault displacement hazard analyses were conducted to develop design displacement demands. Subsequently, numerical analyses were performed to evaluate the fault rupture-induced demands on a pier foundation in terms of displacements and rotations. Initially, analyses were performed that model the free field fault rupture propagation to the ground surface of the fault to ensure that the basic site characteristics are captured. Subsequently, the foundation elements were introduced in the model and the fault rupture is simulated again. The interaction and influence of the foundation on the fault rupture propagation is calculated, and the consequent demands and distortions of the foundation block provide a basis for structural engineers to design the bridge.IntroductionThe Izmit Bay bridge, a 3-km-long suspension bridge that crosses Izmit Bay in Turkey, is planned to be constructed in one of the most seismically active places in the world. The south approach structures for the Izmit Bay Bridge along the western side of the Hersek peninsula bring the bridge down from on the order of El. 60 meters at the South Anchorage to an elevated embankment approximately 1.3 km farther south (Figure 1). The south approach structures are located within a zone of secondary deformation around the primary trace of the North Anatolian Fault. The concept design team has developed a concept design for a “viaduct” structure that consists of 10 spans with lengths varying between 136 m and 100 m and two back spans one of 125 m, attached to the main bridge and the other of 74 m attached to the south embankment."

Jan 1, 2017

By José Carlos A. Cintra

This paper addresses a new experimental procedure to measure the shaft friction and the base resistance of bored piles during static load tests. It is proposed that a set of polystyrene foam discs, placed between the shaft and the base of the pile, be used instead of the usual instrumentation. Throughout the initial stages of the loading test, the foam discs will allow only the mobilization of the shaft friction. The load x settlement curve clearly shows that the shaft friction vanishes at low settlement values. As the load test proceeds, the base resistance is also mobilized. This procedure was used in two belled piles bored at the Experimental Foundation Field of the University of São Paulo, at São Carlos, Brazil. Both piles were 8 m long and had a shaft diameter of 0.6 m. The enlarged base had a diameter of 1.5 m and a height of 0.9 m. Twenty foam discs with a thickness of 20 mm each were placed between the enlarged base and the shaft of the pile. The load tests indicated ultimate shaft frictions of 28 and 30 kPa for measured settlements of 8.98 and 7.39 mm. Base resistance values at failure were 617 and 499 kPa, for a chosen settlement of 10% of the pile base diameter. The proposed approach seems to be straightforward, efficient and inexpensive.

Jan 1, 2002

By Kiyotaka Ohno, Nobushige Yasuoka, Yosuke Hioki

"The diameter of improved columns adopted by the original DJM Method had been 1000 mm, however, in order to comply with the social need for construction cost reduction, the Expanded Dry Jet Mixing (EX-DJM) Method with maximum column diameter expanded to 1300 mm was developed between 1998 and 2001 and has been widely applied since then. From the first application of EX-DJM in January 2002 for a first construction project, the total volume of improved soil has reached 325,000 m3 in 17 projects up to September 2014. Because of the advantages of the EX-DJM such as reduction of construction costs and periods leading to reduction in the number of improved columns, adoption of this method is expected to increase in the future. This paper describes the advantages of the EX-DJM, its construction results and case examples including those applied to restoration projects after the Great East Japan Earthquake, 2011.1. BACKGROUND OF DEVELOPMENTThe Dry Jet Mixing (DJM) Method is a soil stabilization method in which a powdery or granular binder is pneumatically fed into and mixed with soft soil to induce chemical reactions that stabilize and strengthen the soil. It was developed by government - private collaboration in Japan between 1977 and 1979. Up to March 2014, the total volume of soil improved by DJM method reached 33,500,000 m3. The initial diameter of improved columns of the original DJM Method was 1000 mm. In order to comply with the social need for construction cost reduction, the Expanded Dry Jet Mixing (EX-DJM) Method with maximum column diameter 1300 mm was developed between 1998 and 2001.2. ADVANTAGES OF EX-DJMThe construction equipment for the EX-DJM consists of two major parts, which are DJM machine and binder plant are shown in Fig. 1.The construction machine is of double mixing-shaft type with its column diameter expanded to 1200mm or 1300mm. In association with the increase in the column diameter, the binder feeder has also increased its discharge rate by approximately 1.69 times. Same as the increase rate of the area of original diameter 1000mm to diameter 1300mm are shown in Fig. 4."

Jan 1, 2015

By Kiyotaka Ohno, Nobushige Yasuoka, Yosuke Hioki

"The diameter of improved columns adopted by the original DJM Method had been 1000 mm, however, in order to comply with the social need for construction cost reduction, the Expanded Dry Jet Mixing (EX-DJM) Method with maximum column diameter expanded to 1300 mm was developed between 1998 and 2001 and has been widely applied since then. From the first application of EX-DJM in January 2002 for a first construction project, the total volume of improved soil has reached 325,000 m3 in 17 projects up to September 2014. Because of the advantages of the EX-DJM such as reduction of construction costs and periods leading to reduction in the number of improved columns, adoption of this method is expected to increase in the future. This paper describes the advantages of the EX-DJM, its construction results and case examples including those applied to restoration projects after the Great East Japan Earthquake, 2011.1. BACKGROUND OF DEVELOPMENTThe Dry Jet Mixing (DJM) Method is a soil stabilization method in which a powdery or granular binder is pneumatically fed into and mixed with soft soil to induce chemical reactions that stabilize and strengthen the soil. It was developed by government - private collaboration in Japan between 1977 and 1979. Up to March 2014, the total volume of soil improved by DJM method reached 33,500,000 m3. The initial diameter of improved columns of the original DJM Method was 1000 mm. In order to comply with the social need for construction cost reduction, the Expanded Dry Jet Mixing (EX-DJM) Method with maximum column diameter 1300 mm was developed between 1998 and 2001.2. ADVANTAGES OF EX-DJMThe construction equipment for the EX-DJM consists of two major parts, which are DJM machine and binder plant are shown in Fig. 1.The construction machine is of double mixing-shaft type with its column diameter expanded to 1200mm or 1300mm. In association with the increase in the column diameter, the binder feeder has also increased its discharge rate by approximately 1.69 times. Same as the increase rate of the area of original diameter 1000mm to diameter 1300mm are shown in Fig. 4."

Jan 1, 2015

By Ed Revoort, Robert Schippers

In Rotterdam in the Netherlands the project ‘De Zalmhaven’ is being developed. The project consists of the realization of houses, parking facilities, two residential towers of 70 m and a residential high rise of 215 m. An artist impression for the project is given in figure 1. For the high rise a new development in the use of large diameter, drilled piles with a steel casing has been successfully utilized. In this article the installation method of 65 m long steel drilled piles in two consecutive sections is presented. The settlements for the building (and the influence on its surroundings) have been analyzed in detail using 3D Finite Element calculations, which will also be discussed. Finally there is focus on the results of settlement measurements carried out during construction in relation to the settlement prognosis.

May 1, 2022

By Shawna Munn, Carol Dounitch, Erika Acton

The EQ Bank Tower, a 24-storey office tower with 4 levels of underground parking, is currently under construction at 25 Ontario Street in the downtown core of Toronto, Canada. The tower geometry required an 18 m (60 ft) deep excavation inside an existing 3-storey 100-year-old façade, to be retained in place throughout construction. This presented a variety of design challenges that required several innovations and a customized monitoring program. In this paper, we will discuss two major challenges, and highlight the innovative and adaptable solutions carried out using performance-based design leveraging the observational method. The first was installation of a shoring system in a 500 mm (20 in) gap between the historical façade and a live gas main. The second involved excavating 10 m (33 ft) into expansive shale bedrock adjacent to a sensitive neighbouring building.

Oct 1, 2022

By W. G. K. Fleming

The general history of piling is traced up to the present time with regard to the evolution of methods and materials. The processes have been strongly influenced by developments in basic equipment and industrial change. It is noticeable that in the twentieth century more progress has taken place than in the many previous centuries. It has been strongly influenced by the general development of Soil Mechanics. Test loading is probably the most effective way to assess the success of designs and many empirical relationships have been challenged through it. As we approach a new century it appears that it will be an age of rapid equipment development, with much enhancement of understanding of what has been done. Processes of automatic construction and testing will becoming commonplace. These changes will narrow the limits of conventional scatter that have come to be accepted and to a large extent will be driven by political efforts to curtail energy consumption, to raise standards of quality and reliability, and to conserve the environment. 1. Ancient history. Piling is an ancient art. Its first mention in history is from Herodotus, the first person to commit an account of his times to the written word in the years 557 to 479 BC. He evidently had a strong interest in engineering matters because he wrote of building, brick making, reinforced brickwork, river training, canal building, bridge construction, tunnelling and its acoustic detection and piling. The piling reference comes from Book 5 at paragraph 16.

Jan 1, 1999

By Richard T. Stain

"In 2001, a pile trial site was established at Limelette in Belgium consisting of 25 displacement screw piles and 5 driven pre-cast piles. Interested parties were invited to participate in a pile prediction event, whereby they would submit predicted static load test behaviour in the form of load settlement plots. These predictions could be based on soil investigation results supplied by the organizers, or dynamic load test measurements.Following the submission deadline, the organisers released the results of static load tests for comparison.Of all the six participants, including Statnamic, the SIMBAT method was independently accredited with achieving the best predictions.This paper examines at the differences between SIMBAT and other systems, and presents the correlations from the Limelette trial.INTRODUCTIONThe Belgian Building Research Institute (BBRI) initiated an ambitious research programme involving the construction and testing of some 60 trial piles spread between two sites, a clay site at Sint Kateline Waver and a sandy site at the BBRI headquarters at Limelette. The project was financed largely by the Belgian Ministry of Economic affairs. (ref 1.) This paper refers only to the second site.At Limelette, six different types of displacement pile were installed: one driven pre-cast and five cast in place screw piles - Atlas, DeWaal, Fundex, Olivier and Omega. A detailed site investigation was carried out including in-situ and laboratory tests.An international pile capacity prediction event was publicised, participants being invited to predict static pile behaviour. Predictions could be based on:"

Jan 1, 2005

By Matthew Janes

The new Bow office complex will become the new headquarters of EnCana Corporation, a leading Canadian oil and gas company. The shoring system, encompassing nearly two city blocks and excavated to a depth of 20.5 m, supported surrounding utilities and buildings in downtown Calgary. Past excavations in the area experienced large amounts of rock movement, the mechanics of which were poorly understood. The focus of this paper is the design process and construction results concerning rock movement and the effectiveness of the shoring structure. A lack of information regarding the local in-situ stresses and shear band propagation in the bedrock led to research of case studies in the Calgary area and a peer review from local experts. Several geotechnical scenarios were analyzed using FLAC to account for varying residual rock stresses and the location and composition of weak rock layers suspected of causing shear band movement. Movement characteristics were predicted that would identify the rock deformation mechanic throughout the construction process. A detailed monitoring programme composed of precision monitoring targets, inclinometers, and extensometers was established to provide accuracy and redundancy in establishing the movement of the rock and excavation support structure. The results of the programme were used to identify the rock deformation mechanics and further refine the FLAC analysis. To date, monitoring indicates that localized shear band effect is the leading cause of rock movement. The phenomenon appears to be directionally dependent and strongly correlated to excavation extent.

Jan 1, 2008

By Jonathan J. Dewsbury

It is argued that approximate computer based methods are only suited to modelling conventional piled rafts, for pile enhanced rafts where the interactions will be non linear three dimensional finite element analysis is required. However current 3D finite element analysis often relies on symmetry to reduce computational cost and there are concerns over the dependency of the results on the user. Therefore a new strategy within the finite element framework has been proposed. The main advantage of this strategy is that each stage of the model can be checked for consistency. There is also the added benefit that non symmetrical models can easily be constructed by tying the validated components together without dramatic increases in computational time. The proposed strategy compared well to the published results of a hypothetical example of a piled raft previously analysed with numerous methods by Poulos et al. (1997).

Jan 1, 2010

By Maurice Guillaud

The most striking innovations on diaphragm-wall construction plant are those associated with continuous real-time trajectory monitoring of the excavating tool (either a grab or a hydro-cutter). The recent equipments are fitted with clinometers and gyrometers to control deflection, rotation or deviation from the vertical, thus allowing to install diaphragm-walls with a verticality accuracy of less than 0.3%. One of the greatest advantages of extensive use of on-board IT systems on the Hydrocutters and hydraulic grab machines is that it aids quality control by automatically producing complete real-time reports of all excavating data (verticality, depth, type of ground, rate of progress, stoppages, etc.). These reports are available to the Engineer, providing the total transparency required for Works Supervision and the Quality Assurance Plan. They also provide the Contractor with input data for databases used for optimising efficiency and progress criteria on future jobs.

Jan 1, 2002

By Ronnie W. Sisk

1. Troubles start early - Inadequate Geotechnical Data A. Owners think they are saving money by allowing limited soil borings at their site. This places a high gamble on the bidders and the Lump Sum Price will be higher. B. Inaccurate elevations on soil reports. a. Surprises in depths - over or under design bid bottom elevations. 1. Requires backfill and extraction of casing that is too short for the greater depth of the drilled shaft. 2. Redrill utilizing longer casings. 3. Softer earth (backfill) can cause difficulties in redrilling such as less quantity extracted on the auger and maintaining plumbness. 4. Greater concrete overrun. b. Extreme under depths. 1. Excessive concrete is placed as a result of planning for a deeper shaft. c. Geotechnical report that does not supply a layout of boring locations. d. Design Engineer does not have a basic knowledge of how a caisson is installed.

Jan 1, 1988