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By Sanjeev Malhotra

"This paper presents the results of a pile installation monitoring and performance assessment program for pile foundations supporting 14 piers and 2 abutments of the 1700-ft long bridge crossing over a river in Baltimore, Maryland. Dynamic measurements were conducted during installation and restrike of 16 test piles, one at each support location. The foundation piles were 30-inch diameter, 0.75 inch thick pipe piles at the piers and 24-inch diameter, 0.5 inch thick at the abutments. The piles at the piers were approximately 100 ft long and were designed to carry 260 kips service load with a factor of safety of 2.25. The piles were driven open ended into a variable site stratigraphy containing recent deposits of organic clayey silts near the mudline followed by loose to medium dense sand, with some silt, and then by soil deposits from the Cretaceous period consisting primarily of dense to very dense, poorly to well graded sands and gravels and cobbles, with occasional seams of very hard to very stiff, low to moderate plasticity silts and clays. This paper presents the approach taken to evaluate the driven index piles and to develop criteria for driving production piles. It provides the Engineer with some data on pile driveability in Cretaceous soils in the Baltimore area, soil set-up effect, and an estimate of pile capacity.INTRODUCTIONThe typical approach to pile foundation design and construction should include an indicator pile program with dynamic measurements and a static load test program. However very often paucity of funds and schedule constraints cause an owner to do away with conventional static load testing which can take $25,000 to $100,000 and several weeks per test. This paper examines an alternate (though not equivalent) truncated approach to foundation assessment and presents a case history where this approach was implemented.Dynamic measurements were conducted during pile installation for the 14 piers and 2 abutments of the new 1700-ft long bridge over a river in Baltimore, Maryland. Strain transducers and accelerometers were attached to the pile top during initial driving and restrike of 16 pipe piles. The foundation piles consisted of 30-inch outside diameter, 0.75-inch thick pipe piles at the piers and 24-inch outside diameter, 0.5 inch thick at the abutments. The piles were driven open ended into a variable site stratigraphy. The approach taken to assess the foundation performance included 1) a pre-field wave equation driveability analyses, 2) field pile driving measurements, 3) post-field Case Pile Wave Equation Analyses (CAPWAP), and, 4) revised wave equation analyses based on field and CAPWAP data. The following sections describe in greater detail each of the steps taken to assess foundation performance and the results obtained."

Jan 1, 2005

By Roberto A. Lopez, Eric Lindquist, Jon Bussiere, Dean Iwasa

"The new 11-story U.S. Federal Courthouse building in downtown Los Angeles demanded a cost effective foundation system capable of attaining a strict total settlement criterion of 0.5 inches (12 mm) under high applied loads. A design-build ground improvement system consisting of 3 ft (0.9 m) and 7 ft (2.1 m) diameter deep soil mix (DSM) columns embedded into the relatively soft Fernando Formation bedrock was selected for the project. The DSM columns support applied stresses of up to 8,800 psf from four large concrete core elements that transfer concentrated building loads to a 3 to 6 ft (0.9 to 1.8 m) thick reinforced concrete mat. The soil mixing ground improvement solution provided flexibility by allowing installation of the DSM columns around existing belled caissons left in place from prior structures, and by allowing repositioning of some of the DSM columns to avoid other existing obstructions in the fill. DSM spoils were used to construct a 2 ft (0.6 m) thick load transfer platform on top of the DSM columns. Quality control measures included utilizing equipment outfitted with automated data acquisition systems, performing three full scale load tests, performing daily wet-mix sampling and compression testing, performing full-depth coring and unconfined compression testing on core samples, and using a borehole acoustic televiewer to evaluate the uniformity of the DSM columns where core recovery was problematic. The results of subsurface investigation and the load tests were used to develop 3-dimensional finite differences models for evaluating stress distribution and deformation of the foundation system.INTRODUCTIONThe new U.S. Federal Courthouse building is currently under construction in downtown Los Angeles, California. The new courthouse will be 11 stories tall with one partial below-grade B1 basement level. The building will have four structural core elements that extend from the main building foundation at the B1 level to the top of the structure. The majority of the building loads will be transferred through the structural core elements to a new 3 to 6 ft (0.9 to 1.8 m) thick reinforced concrete mat beneath the central portion of the structure. The foundation pressures beneath each of the core element locations will be approximately 6,200 to 8,800 psf (300 to 420 kPa) with lower foundation pressures at locations farther away from the central core area."

Jan 1, 2015

By Manasi Wijerathna, D. S. Liyanapathirana

"Deep cement mixing is a popular soft ground improving technology that improves the bearing capacity and settlement characteristics of natural soil. When Deep Cement Mixed (DCM) columns are installed attached to each other in a wall configuration, the walls are capable of resisting bending moments and shear forces in the direction transverse to the columns. Therefore, installing DCM walls beneath the embankment slope perpendicular to the alignment of the embankment is a proper solution to prevent excessive lateral deformations of the embankment. Previous research studies have shown that failure patterns of DCM column walls are different to failure patterns of individual DCM column rows, under lateral loads. This study investigates the failure patterns of embankments where DCM column walls are located beneath the slopes, with respect to DCM wall strength, DCM column wall width and the spacing between DCM walls. 2D and 3D numerical models developed using the ABAQUS/standard finite element programme, were used in this investigation. Results show that the DCM wall strength and width of the DCM wall have a significant influence on the failure mode and the critical failure surface of the embankment. 3D simulation results demonstrate that the failure due to soil extrusion between columns was less pronounced in embankments improved with DCM walls, due to the interaction between the DCM walls and the surrounding natural soil.INTRODUCTIONEmbankments constructed over soft ground are highly susceptible to global slope failure and excessive displacements due to combined effects of vertical and lateral loads beneath the embankment slope (Zheng et al., 2009, Han and Gabr, 2002). The overall stability of the embankment can be significantly improved by improving the soil beneath the slope of the embankment using Deep Cement Mixed (DCM) column rows or overlapped DCM column walls (Jamsawang et al., 2015, Larsson and Broms, 2000, Topolniki, 2004, Broms, 1999). According to the literature, the improved ground experience different failure modes other than shear failure, such as separation of columns, overturning, shear failure along the columns or dowel action (Broms, 1999). Some of the failure modes reported by Broms (1999) are shown in Fig. 1. The ultimate failure mode depends on the geometry and the strength of the improved ground (Jamsawang et al., 2015, Kitazume and Maruyama, 2006, Kitazume and Maruyama, 2007)."

Jan 1, 1900

By Braxton P. Erbe, Douglas C. Brunot

A variety of systems and techniques exist to support deep excavations where sloping is not feasible. This paper will explore an example project involving the use of pre-engineered hydraulic bracing systems to support sheet pile walls. Challenges on site that drove the final design include a high water table, irregular excavation geometry, and underground obstructions. The hydraulic system, connected by pins and not requiring welds, allowed for quick deployment and the modularity to change as required due to unforeseen site conditions.

By Kozo Takeda, Arashi Shimano

"Dry Jet Mixing (DJM) method as the representative deep mixing technique has been demonstrating best practice on ground mitigation works coping with complicated soil condition and limited site space. This technique plays an important role in many projects to stabilize soft ground involving troubles like sliding failure, settlement, bearing capacity etc. Serious disasters caused larger earthquakes make great demand on the application of deep soil mixing these days. Special design and alignment of deep soil mixing has been established against to liquefaction and serious failure due to liquefaction. In this paper, representative example of liquefaction mitigation by DJM method is summarized. The paper also present result of surveillance of sites installed DJM col umns after attack by Tohoku Pacific Ocean Earthquake. Performance of DJM columns suffered the earthquake is demonstrated at several sites even with conventional column alignment.INTRODUCTIONThe DJM method is a representative deep soil mixing technique of dry mixing manner in Japan. DJM can successfully install soil mixing columns trough automatically controlled binder injection based on pneumatic feeding theory and cumulative experiences.This method was joint-developed in 1978 by private organization under initiative of the Public Works Research Institute of the Ministry of Construction as the optimum method for improving the Japanese soft ground. Figure 1 shows full view of the DJM construction system. Figure 2 illustrates DJM working system indicating Binder Feeding Plant side and Mixing Machine side respectively.As typical soil mitigation method, many projects related with rivers and roads and city development has required DJM technology. The total number of the projects applying DJM has exceeded 5,000 with the total treated soil volume more than 32,000,000 m3 by the end of fiscal year 2013."

Jan 1, 2015

By George Aristorenas, Carlos Englert, Jesús Gómez

"Laboratory test data of strain softening soils exhibit the development of a maximum (peak) shear strength followed by a decrease in the strength with continued straining. The rate of strength loss decreases such that an asymptotic minimum value, known as the residual strength, is approached. This paper presents an investigation of the evolution of strength degradation in excavation supported soils that exhibit strain softening behavior. The paper presents a numerical investigation of excavation support of slicken-sided clay, and results of shear testing on materials with similar strain softening behavior. A strain softening constitutive law is presented that can be used with the finite element computer software Plaxis for analysis of excavation support. A typical design section of a deep excavation support in stiff, fissured clay is presented that illustrates the limitations and conservatism of the residual strength approach for excavation support design. Finally, a discussion is presented on the impact of stiffer walls such as diaphragm walls, compared to less stiff systems such as sheet piles, on the design parameters.INTRODUCTIONIn the Washington, D.C. metropolitan area, the Potomac Formation is generally composed of stiff, fissured clays. Geotechnical engineers often associate the presence of slicken-sided planes within the formation as evidence that the soil cannot develop its peak strength. Although it is unclear how old and continuous these slicken-sided planes are, their occurrence, persistence and orientation appear to be somewhat random. Due to this uncertainty, the design of open cut slopes in these materials is often conservatively performed assuming residual shear strength values. This design approach may be justified for long-term open cuts when there is limited amount of geotechnical information and in view of back stability analyses of past slope failures. Furthermore, the lack of confinement in open cuts allows relatively high shear strains near the surface and toe throughout their existence, which promote mobilization of post-peak strength values and the ensuing progressive failure. Indeed, such behavior has been discussed in the past (Skempton, 1970; Schnabel et. al., 1982; Derrenbacher, 1998). A thorough study by Mesri et. al. (2003) of numerous slope failures concludes that the lower bound strength for stability analysis of non-failed slopes is the fully softened strength, which is intermediate between the peak and residual strengths, but that part of the slip surface may be in a residual condition prior to failure."

Jan 1, 2015

By Ground Improvement Committee

The evaluation of earthquake-induced liquefaction has become a routine part of geotechnical engineering design. For a given project, if an analysis identifies a potential for liquefaction and the consequences of liquefaction are deemed unacceptable, then some form of hazard mitigation is required. Mitigation efforts may consist of removing the liquefiable soils, bypassing the liquefiable soils with deep foundations, structurally accommodating the deformations or strength loss caused by liquefaction, or preventing the onset of liquefaction through ground improvement. The fundamental ground improvement mechanisms for liquefaction mitigation include densification, drainage, and reinforcement. When evaluating, recommending and specifying various ground improvement methods for liquefaction mitigation, practitioners should understand the fundamental mechanics involved and applicability and limitations of the various methods. The DFI Ground Improvement Committee offers a review of the fundamental mechanics and commentary on the applicability and limitations of each method to provide clarity and guidance on the issues related to ground improvement for liquefaction mitigation.

Aug 1, 2013

By Seth H. Hamblin, John E. Regan, Dimitrios Palantzas

"Through reliability-based calibration of larger pile load test databases, recent developments of the Load Resistance Factor Design (LRFD) methods, which include geotechnical load and resistance factors for deep foundations design, have advanced the state of practice for geotechnical engineering. These load test databases upon which the current geotechnical load and resistance factors have been developed are limited, however, and do not provide sufficient data to support the development of resistance factors for uplift (tension) pile capacity. As such, some recommended resistance factors for uplift capacity estimation methods are simply derived by reducing the recommended resistance factors for piles in compression by a factor of 0.10.The results of three (3) tension loading tests performed to failure on 508 mm (20- in) square precast, prestressed concrete piles, driven though granular soil in southeastern Massachusetts, are presented and compared to static pile capacity calculations and dynamic analyses performed using the Pile Driving Analyzer (PDA) during installation. These results are presented along with current recommended LRFD resistance factors for driven piles under uplift (tension) loading conditions. These comparisons offer an assessment of the applicability and limitations of current resistance factors methods for piles under uplift loading and may be useful additions to the existing database for future calibrations of LRFD resistance factors for driven prestressed concrete piles in sand.IntroductionIn 2010, two (2) natural draft cooling towers were constructed by Kiewit (Kiewit) Construction Company of Woodcliff Lake, New Jersey at the Brayton Point Power Station in Somerset, Massachusetts. These massive 500 foot tall, 400 foot diameter cooling towers were designed to convert the existing “open loop” system into a “closed loop system” thereby dramatically reducing the thermal impact to Mt. Hope Bay.Based on design guidance from the German VBG Design Code and the Massachusetts State Building Code (MSBC), tension (i.e. uplift) and lateral loads due to wind loads and design seismic events represented the critical loading conditions.Weighing approximately 190,000 kips upon completion, the cooling tower loads are transferred to 44 foundation nodes (i.e. pile caps) evenly spaced along ring beams which run the circular perimeter of each tower base. Each pile cap node was designed to resist a 2,000 ton compression load, 200 tons in tension (i.e. uplift), and 600 tons in the lateral direction."

Jan 1, 2015

By Jim Glider, Noah Miner

The Gordie Howe International Bridge is a project to build a cable-stayed bridge and border crossing across the Detroit River. With a span length of 2,800-ft (853.4 meters), the Gordie Howe International Bridge will have the longest main span of any cable-stayed bridge in North America. Each tower has two legs that are supported by six drilled shafts each for a total of 12. The tower shafts are 9.84 feet in diameter (3-m) and extend well into bedrock. 17 each, 6.6 feet (2-m) drilled shafts were built to support the aging river bulkhead and replace shipping bollards. In addition to shallow groundwater fed by the Detroit River, artesian conditions at depth result in a water head that is approximately 17.2-ft (5.2-m) above surface. At 95-ft (29-m) below grade Dundee Limestone, of the Detroit River Group, is moderately weathered and fracture density decreases with depth. The Dundee Limestone strength ranges from 8-ksi (55.1-MPa) to 12-ksi (82-MPa) and may carry hydrogen sulfide in fractures. Working through casing that sticks three stories out of the ground is less than ideal, but was necessary to maintain a positive fluid head and prevent artesian-related quality issues. The sheer scale of the bridge forces required a load test configuration that could impart an equivalent static load of over 38,000,000 pounds (170-MN). A suite of QA/QC tests was developed to ensure the shafts would meet the project plans and specifications to include critical base cleanliness criteria. Interesting CSL and TIP results obtained highlight the strengths and weaknesses of each test method. Cleaning drilling fluids with a centrifuge allowed recycling of product and reduced exposure to environmental contaminate exposure. Having large construction equipment working next to the river presented challenges in working pad design. A driven pile system was developed to support high oscillator forces and protect the aging seawall.

Sep 8, 2021

By Clayton A. Signor

Abstract: Expansive soils cause more damage to structures annually than a combination of other major natural disasters. Because of the cost to our society, all means and methods need to be fully explored to mitigate the problems associated with expansive soils. This study will present a foundation design approach that is underutilized in this application, driven piles. The main objective of the study is to present pile test results and analysis from four driven pile project sites in three types of expansive soils found in central Texas: Del Rio formation, Taylor/Navarro formation, and expansive alluvium. High strain dynamic pile tests were conducted on each of the four studies with rigorous signal matching analysis from the CAse Pile Wave Analysis Program (CAPWAP). Ultimate pile capacities ranged from 73 to 311 kips with an average of 61% of the total capacity coming from the pile shaft and were two to six times the structural capacity needed. Allowable loads calculated from Modified Gates dynamic formula best modeled allowable test results. Average unit skin frictions ranged from 0.50 to 4.71 ksf. Restrike pile tests of 1 to 17 days after initial driving reported 30 to 100% shaft capacity gain. All open-ended pipe piles driven produced soil plugs ranging from 4 to 14 feet thick. Small diameter, thick-walled, open-ended pipe piles reached penetration of twice the depth of designated zone of seasonal moisture change without problem. The observed production rate of the driven piles was on average 8 minutes, which implied daily production of 15 to 40 piles. Predrills or augered holes should be specified for underground obstructions found in soil investigation.

By John C. Niedzielski

The existing US-70 Bridge over the Gila River at Bylas, Arizona is planned to be replaced due to its current poor condition. The replacement bridge is planned to be a 15-span, 1,904-foot (580 meter) long bridge, the third-longest bridge in the state highway system. Within the Gila River floodplain, granular alluvial soil is underlain by cohesive lacustrine soil; bedrock was expected due to nearby terrain but not encountered within the geotechnical exploration depth of 166.5 feet (51 meters) or less. Based on the anticipated loading conditions, design scour depths and the soil conditions, the full structural loads are carried by large diameter drilled shafts; therefore accurately determining the axial capacity of the proposed drilled shafts has important practical and safety implications. The conventional methods for axial capacity determination may be overly conservative to use for design in the site?s layered granular and hard clay soils. An Osterberg cell load test was performed to obtain detailed information on the load transfer from the drilled shaft in side friction and base resistance to allow optimization of the bridge foundation design. The full-scale field test played a significant role in the design of the project?s deep foundations, notably, by incorporating the specific subsoil properties and consequently, an exact prediction of the load-settlement behavior under loading. This paper provides the results of the geotechnical site investigations, drilled shaft load testing procedures, and shaft load distribution from the load test results. Comparisons were developed between predicted axial capacities of drilled shafts using several design methodologies and the axial capacity measured from static load testing. The load test results showed that underestimation of the axial capacity is evident using conventional methodologies. The exact prediction of the load-settlement behavior under loading combined with a site-specific design approach, resulted in a substantial reduction of foundation costs due to reduced drilled shaft dimensions.

By EFFC/DFI Concrete Task Group

Concrete technology continues to advance rapidly and modern mixes with five components – cement, additions, aggregates, (chemical) admixtures and water – often have characteristics which differ significantly from the older three component mixes – cement, aggregates and water. Recent trends have favoured higher strength classes and lower water/cement ratios, resulting in greater dependence on admixtures to compensate for reduced workability and to meet the (often competing) demands for workability in the fresh state and setting time. The application of testing methods which reflect the true rheological properties of the concrete has not developed at the same rate as the mixes themselves and it is still not uncommon for the slump or flow table test to be used as the only acceptance test for fresh concrete.A joint review of problems in bored piles (drilled shafts) and diaphragm walls cast using tremie methods by both the European Federation of Foundation Contractors (EFFC) and the Deep Foundations Institute in the United States (DFI) identified a common issue. The review determined that many of the problems were caused by (or in part due to) the use of inadequate concrete mixes with inadequate workability, or insufficient stability or robustness of the mixes. It further identified the primary causes as inadequate concrete specifications and inadequate testing procedures. The consequences of these problems are often significant and it has been recognised that spending more time and money on getting the concrete right is the most cost effective approach.A joint Concrete Task Group was set up by EFFC and DFI in 2014 to look at this issue and this guide is the output from that Task Group. A research and development project, funded by the Sponsors of this guide, is being carried out by the Technical University of Munich in conjunction with the Missouri University of Science and Technology. This project includes desk studies, laboratory testing, and onsite testing at worksites in Europe and the US. The research work will be completed during 2016.

Jan 1, 2016

By James Coull, Brian Wilson, David Siddle

"In 2012, Golder Construction Inc. was awarded a Design-Build contract for the design and construction of an extensive, deep ground improvement scheme to support up to 20 metres (66 ft) high Mechanically Stabilized Earth walls and bulk earthworks required for the development of the proposed Kitimat Liquefied Natural Gas (LNG) facility at Bish Cove, British Columbia (BC). Utilizing Cutter Soil Mixing (CSM) to construct barrettes consisting of overlapping rectangular panels of in-situ cement-treated soils, a deep mixing scheme, covering an area of approximately 12,900 m2 (15,430 yd2) and comprising some 1645 CSM panels to depths of up to 30.7 m (101 ft), was developed to provide the required static and seismic stability for the LNG structures, and meet the project-specific performance criteria.CSM panels were constructed through varying thicknesses and discontinuous layers of fine-grained, very soft to soft marine deposits, and loose to compact sands, with occasional interbeds of dense sands and gravels. Panel completion criteria was based on soil response factors, as measured by the CSM equipment, with the design requiring a typical embedment of about 2 m (7 ft) into dense silty sand to sand and gravel to provide the required bearing. A total volume of approximately 73,900 m3 (96,660 yd3) of soil was treated with cement to consistently yield average unconfined compressive strengths exceeding 2.5 MPa (363 psi).This paper outlines the challenges associated with the construction and quality control of this large deep mixing scheme in highly variable geotechnical conditions at a remote location with barge-only access, and limited communication facilities. Specifically the paper will discuss the logistical challenges faced and solutions adopted for the project; equipment redundancy requirements for a 24/7 operation; the impacts of wear and tear, as well as variability in subsurface conditions on productivity; quality control processes adopted for the project, including the value of provision of an on-site laboratory; and materials handling issues, and their impacts on mix design and quality control."

Jan 1, 2017

By Dan Brown

Deep foundation contracting for transportation projects in the United States has typically followed the design-bid-build model in which contractors bid on a specific work product according to relatively inflexible prescriptive specifications. With continuous flight auger piling and the many types of proprietary drilled displacement auger piling, there appear to be advantages to contracting this work according to a different model. This paper provides a discussion of the use of a performance specification for this work in which the contractor has greater freedom to choose the most appropriate foundation system and also greater responsibility for the performance of the completed foundation. With public agencies subject to open bidding, this type of contractual arrangement presents opportunities to encourage innovation. There are also challenges for implementation in public works projects, notably the selection of qualified contractors and the verification of performance requirements on production foundations.

Jan 1, 2006

By Waddah Akili

The demand on pile installation in the offshore of the Arabian Gulf has, over the last two decades, experienced unprecedented boom, triggered by the construction of platforms, to help facilitate the production and transport of oil and gas. Available borehole data show that ground conditions for pile installation in the offshore is highly variable, resulting in misassessment of insitu conditions, leading to a huge discrepancy between ultimate pile capacities, based on design, and actual capacities after installation. The paper makes use of pile installation records derived from several platforms in the offshore of the state of Qatar, the Gulf Region. More specifically, the paper evaluates “as–installed” ultimate capacities and safety factors, recommends remedial installation procedures, and proposes a means for determining pile acceptability for piles meeting refusal short of design penetration. The paper offers what is believed to be relevant recommendations to guide the design and installation of future offshore structures; enabling the geotechnical community in the Region to solve their current offshore pile installation problems and gain an added margin of confidence regarding the ultimate capacity of installed piles.

By Ryan Weaver, Travis Coleman

The drilled shafts that support transmission lines and substations have been increasingly subject to testing to assess the integrity of placed concrete. Cross-hole Sonic Logging (CSL) has been used, but large diameter shafts with challenging site access are generally more favorable to Thermal Integrity Profiling (TIP) testing. TIP testing assesses the shafts based on measurements of the concrete temperature during curing. The TIP results provide assessment of integrity both within and outside the cage, along with information about the alignment of the cage and concrete cover. This data has allowed shafts with imperfect results to be subject to more detailed structural evaluations. However, it may not be well understood how to use this additional information by designers and engineers. The purpose of this paper is to present TIP results of transmission line foundations, both with and without issues with integrity, including cage shifting, minimal concrete cover, or soil inclusions. The intent is to provide general guidelines of the issues that merit additional investigation and those that should be recognized as inconsistencies inherent to underground construction. BACKGROUND This paper is intended to discuss some of the drilled shaft evaluations made when TIP testing is performed. The authors of this paper were recently involved with a transmission line project that was designed and constructed for a Confidential Utility Client located in the Midwest United States. The project was delivered as an Engineering, Procurement, and Construction (EPC) contract with the electrical line construction company as the prime contractor. The contractor then subcontracted several parts of the work which included engineering for transmission line and foundation design, foundation construction, and third-party testing intended to evaluate the concrete homogeneity and integrity of the place concrete in the deep foundations. The testing method selected was Thermal Integrity Profiling Method B, which uses thermal sensors embedded in the concrete. The TIP testing was administered by Mr. Travis Coleman with GRL Engineers, Inc. Mr. Ryan Weaver with Burns & McDonnell served as the owner’s engineer and technical consultant for the utility and was responsible for reviewing submitted TIP reports and providing recommendations to the utility on their acceptance, and if there were any issues that would warrant further discussion and analysis.

Jan 1, 2019

By Andrew J. Ciancia

The construction of the Pennsylvania Station in Manhattan, the Beaux-Arts masterpiece, was completed in 1910. In financial ruin, the Pennsylvania Railroad Company sold the station in the 1960?s and the new Madison Square Garden and the Penn Plaza complex were constructed at the site. The demolition of Pennsylvania Station brought public awareness and outcry to protect historic structures and the Landmarks Preservation Commission (LPC) was subsequently established in 1965. In the 1960?s relatively little engineering data was available on the performance of historic structures during adjacent construction and thus, no published criteria were established by the LPC on allowable movements and vibrations. During the late 1970?s a commercial tower was planned adjacent to the landmark Fraunces Tavern Block (FTB) in lower Manhattan. Through negotiations between the LPC and the developer, Dr. M. I. Esrig and the author were retained to monitor the historic block during foundation construction. The monitoring data and building performance compiled from the project formed the basis of the published 1981 ASCE technical paper by Esrig and Ciancia entitled ?The Avoidance of Damage to Historic Structures Resulting from Adjacent Construction?. Based on the ASCE paper, the NYC Department of Buildings adopted Technical Policy and Procedure Notice #10/88 entitled ?Procedures for the Avoidance of Damage to Historic Structures Resulting from Adjacent Construction When Subject to Controlled Inspection by Section 27-724 and for Any Existing Structure Designated by the Commissioner?, June 1988. This paper describes the author?s recent experience during the installation of deep foundations within, or adjacent to, three Manhattan landmark structures. Discussions are provided on the foundation construction, monitoring programs and performances of the three structures.

Jan 1, 2008

By Y. M. Ha, T. D. Nguyen, D. T. Nguyen, H. K. Choi

Conventionally, cement deep mixing (CDM) columns are designed to have constant diameters over the improved depth as this facilitates the construction procedures. However, this design pattern may be inefficient in cases of spread footings or shallow foundations. This paper first briefly introduces principles of an improved CDM method that can create head-enlarged CDM (termed PF) columns. A simple analysis approach was introduced to obtain optimal shape of PF columns that results in minimum settlement. The effectiveness of this improved method over the conventional CDM method was then illustrated by settlement analysis for an actual footing in a case study using two recommended analytical methods in the literature. Analysis results from the case indicated that by using the same amount of soil-cement mixed volumes, settlement from a footing on PF columns can reduce up to 10 % compared with that from the same footing on CDM columns. In addition, a material quantity comparison for the case indicated that to have the same settlement values the volume of each PF column can be reduced of around 10% compared with that of the CDM column. INTRODUCTION The cement deep mixing (CDM) method is one of the most popular methods in ground improvement works. Details on the method such as construction procedures, necessary equipment and recommendations are described in many references or manuals (e.g. Bruce et al. 2013, BS EN 2015, Kitazume and Terashi 2013). Conventionally, CDM columns are designed to have constant diameters over the improved depth as this facilitates the construction procedures. However, this design pattern is found inefficient in cases of spread footings or shallow foundations as the upper soil layers are naturally weaker than the deeper ones but are subjected to larger amount of induced stress from the superstructures.

Jan 1, 2019

By Hee-suk Yun, Dae-jin Hwang, Jeong-woo Seok, Myoung-mo Kim

"In this paper, the accuracy of the data measured by a newly developed displacement measuring system, DPRMs (Digital Pile Penetration and Rebound Monitoring system) and its applicability as a quality control tool were verified by field measurements of pile penetration and rebound for pile driving performed at 3 construction sites and 1 test site. The DPRMs data were found to be much better than handwork data. A new dynamic formula for pile capacities is proposed uses the results of a pilot dynamic load test and the final pile penetration. The ratios of pile capacities obtained by the new formula to those by the dynamic load test were 94%±7.4% in the contrast with 123±28.3% by the 5S formula and 68±24.0% by Hiley's formula. This result shows the superiority of the new formula. The ratios of the maximum compressive stresses calculated by using DPRMs to those calculated by using PDA (Pile Driving Analyzer) were about 90-110±10%. This result confirms the applicability of DPRMs as an overdriving monitoring tool. Two sets of DPRMs were used to measure the 3-D displacement behavior of a pile head at the test site. The more the pile head moves laterally, the less the final set values were expected because of the loss of driving energy, but this trend was not obvious within the limited data obtained at the test site.INTRODUCTIONPile construction monitoring consists of two parts. In the first part, enough capacity of the pile is secured to stand the design load. In the other part, pile damage during driving is prevented. Although several methods can be applied to achieve the first part, PDA is nearly the only tool for measuring pile stress.Several methods such as a static load test, a dynamic load test, an Osterberg cell, and numerous driving equations can determine the pile capacity. Among them, the static load test and the dynamic load test are most widely used. The static load test is advantageous because it has the highest reliability. The disadvantages are as follows: it is costly and time-consuming. Also, the capacity of the pile under construction cannot be evaluated. The dynamic load test has lower reliability than the static load test, but it is cheaper than the static load test, is reliable enough to determine the pile capacity, can evaluate the capacity of a pile during construction, and can offer information about construction conditions such as the pile integrity and the pi le stress during driving. The dynamic load test takes a relatively short time and is low cost compared with the static load test. However, it is still costly, time-consuming, and unnecessary to apply to all piles in the field as a construction measurement tool. Therefore, driving resistance (blowcounts) is commonly measured to confirm the pile capacity at construction sites."

Jan 1, 2005

By Viswanadham B. V. S., Babu K. V

Wind energy is one of the most economical renewable energy sources. In order to support wind turbines onshore or offshore open-ended monopile foundations are widely used. Unlike conventional structures, wind turbine foundations experience a large magnitude of lateral loads in the order of 20 % to 30% of total vertical loads. The presence of soft clayey layers at shallow depth along the coastal region, offers lesser lateral load resistance to monopile foundations. One option to enhance lateral load capacity is by introducing fins to the outer surface of the monopiles. Studies pertaining to lateral load response of finned piles in clayey soils are very sparse. This paper presents some of the numerical model studies on the lateral load response of monopiles and finned piles in soft and stiff clay. In the present study, three-dimensional finite element analyses were performed on monopiles as well as finned piles. Analyses were performed in clay with different consistency varying from soft to stiff. Pile material is mild steel for all analyses. The pile section modeled as linear elastic material whereas soil was modeled as Mohr – Coulomb constitutive model with non-associated flow rule. Monopiles and finned piles having four and eight fins with different fin sizes and configurations are considered during the analyses. Finned piles advantage over monopiles to resist lateral load is highlighted in the present study. The results have shown that fins are effective to enhance the lateral load carrying capacity of monopiles and also it reduces the bending moment in monopiles for a given design load.

Sep 1, 2022