Search Documents

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 K. Rainer Massarsch

"Part 1 of 2 By K. Rainer Massarsch, Geo Engineering AB, Stockholm, SwedenINTRODUCTIONConstruction activities, such as driving of piles and sheet piles, soil compaction or excavation generate noise and vibrations. In populated areas these can have a negative impact on the environment, disturb inhabitants and, under unfavorable conditions, cause damage to buildings and installations. This condition is aggravated by the growing public awareness of environmental issues and the increasing use of vibration-sensitive electronic equipment and machinery in industry. In many countries, environmental regulations are enforced more stringently and limit or even prohibit the use of impact or vibratory hammers. This development has restricted the use of cost-effective foundation methods, such as driven and vibrated piles and sheet piles.Vibration problems are gaining importance in many European countries and extensive research has been performed during the past decade, especially with respect to traffic vibrations (Massarsch, 2004). Significant progress has been made owing to the availability of high-quality field measurements and an improved theoretical understanding of how vibrations are generated and transmitted through soil layers. These findings can also be applied to vibration problems associated with construction activities. However, this information is not yet appreciated by the geotechnical profession and even less by the construction industry.This paper discusses the effects of ground vibrations on the surrounding soil and on buildings, with particular emphasis on the different mechanisms of damage that may occur. Guidance is given on the elements which should be taken into account in an assessment of risks associated with piling projects. A simplified method is proposed for assessing the risk of settlements or strength loss in soil deposits. Limiting vibration levels are presented, based on the Swedish standard, which can be used to assess the risk of damage to buildings. Aconcept to predict ground vibrations caused by pile driving and the mechanisms which control the propagation of ground vibrations, will be presented in the second part of this paper."

Jan 1, 2004

By Ke Yang, Robert Liang

"Drilled shaft foundations are widely used for many types of structures, especially for highway bridges, high rise buildings, and costal structures. The lateral design considerations are crucial for those structures that are subjected to lateral thrust forces, winds, waves, and earthquakes. The p-y analysis is the most widely used method for the analysis and design of drilled shafts for lateral load applications in soils. However, existing p-y criteria were developed based on the lateral load tests on small diameter drilled shafts in soils. Although, a lot of lateral load tests have been conducted, there are a limited number of lateral load tests on large diameter drilled shafts embedded in clay. In this paper, a lateral load test on 2.44 m diameter fully instrumented drilled shafts in clay is presented. The site specific p-y curves are derived based on strain gage readings. The existing p-y curves are found to be much softer than the site specific p-y curves. Correspondingly, the deflection at the top of the test shaft under the maximum applied load is predicted to be eight times larger than the measured value using existing p-y criteria. A new p-y criterion is proposed in this paper. The proposed p-y criterion is proven to be able to capture the site specific p-y curves of the load test and to predict closely the deflections at the top of the test shaft. INTRODUCTIONDrilled shaft foundations are widely used for many types of structures, especially for highway bridges and costal structures. The lateral design considerations are crucial for those structures that are subjected to lateral thrust forces, winds, waves, and earthquakes. Although efforts have been made on studying lateral response of drilled shafts; nevertheless, only limited studies have been published on the behavior of large diameter drilled shafts under lateral loads and the corresponding design methods."

Jan 1, 2005

By Matthias Pulsfort, Jiarui Du, Torsten Wichtmann, Achim v. Blumenthal, Diethard König, Rowena Verst

The influence of the interaction between support fluid and soil, e.g., filter cake formation, on the shear stress transfer in the soil-concrete interface of diaphragm walls and bored piles is still controversially discussed. Actual research on the soil-concrete interface using bentonite suspensions indicates that shear stress transfer is underestimated by existing standards. Investigations on the soil-concrete interface using polymer solutions are rare. Therefore, complementary field investigations and systematic laboratory studies were conducted to analyse the soil-concrete interface using both bentonite suspensions and polymer solutions. Thickness and composition of real-scale filter cakes were investigated on several slurry wall construction sites, where bentonite suspensions were used. Direct shear tests (60 mm x 60 mm) were executed for soilbentonite mixtures with varying amounts of bentonite and different granular fines representing a realistic bandwidth of in-situ filter cake compositions. Larger direct shear tests (300 mm x 300 mm) with preceding horizontal penetration, subsequent vertical tremie concrete placement, and filter cake consolidation were performed using both bentonite suspensions and polymer solutions. The results support the view that shear stress transfer in the soil-concrete interface can be described by a wall friction angle in a range of 25° to 30° for bentonite suspensions and between 35° and 40° for polymer solutions in non-cohesive soils.

May 1, 2022

By Christophe H. Locussol

D.C. United, the professional soccer team located in Washington, D.C., completed a 20,000 seat capacity stadium in July 2018 named Audi Field. The project initially considered a foundation system consisting of roughly 800 prestressed concrete driven piles configured in groups with pile caps. A value engineering alternative proposed in a design-build manner ultimately resulted in the use of 300 single element Auger Cast Piles (ACPs) for the foundation system. The ACPs ranged between 1.5 ft and 4 ft in diameter, were up to 85 ft in length, and were connected through a system of grade beams to accommodate large lateral induced loads. Limitations in conventional analytical methods were encountered during the structural design of the piles due to the complexity of the lateral loading and pile fixity conditions. An innovative approach using advanced finite element modeling that incorporated the framing effects of the grade beams was required to meet the strict movement criteria despite large lateral loads.

By Vishal Pathak, Shailesh A. Godhuly

Ground Modification System in terms of Jet Grouting for soil strengthening and mass stabilization was engaged for a power plant project in an international power project, engineered by L&T-S&L. The site Geology consist of cohesionless type of sandy alluvial deposits (silty fine sand) as the main formation. Ground water table is encountered at shallow depth. Geological interpretation is done using soil investigation data along with CPT’s. This paper discusses design and implementation of jet grout technique to improve the mechanical behaviour of soil. To distribute load evenly from superstructure, a layer of growmast (drainage blanket) is laid above jet grout columns. Settlement evaluation is done using Finite element analysis with Plaxis 2D and Settle 3D. In the project, selected equipment foundations are resting on jet-grout columns including vibratory equipment like 144MW Gas Turbine etc. The project has been commissioned in September 2021 and operating with full capacity.

Sep 1, 2022

By Leo Panian, Ryan Nagle, Priyanshu Singh, Gina Carlson, Wayne Magnusen

"This case study presents the design and construction of an integrated foundation and ground improvement solution utilizing deep soil mixing (DSM) and micropiles. 270 Brannan is a midrise office building in San Francisco that straddles the historic shoreline that was reclaimed in the 19th century. Subsurface conditions include shallow bedrock inland of the historic shoreline, and steeply dipping bedrock overlain by 60 feet of compressible deposits and liquefiable fill on the bay side. Project challenges included mitigating the liquefaction and lateral spreading hazards, addressing settlement concerns in the fill and the bay deposits, developing a cost-effective foundation support solution, assuring satisfactory seismic performance, and addressing construction restrictions with existing adjacent structures.DSM combined with micropiles was identified as the most cost-effective solution for the ground conditions. The DSM panels act both as a liquefaction mitigation mechanism and a foundation support system. Resistance to seismic overturning is provided by uplift-resisting micropiles. The DSM-micropile solution allows the use of efficient conventional spread footing foundations, integrating isolated micropile groups to anchor the shear walls. Successful installation of the system relied on a program of field testing to validate the design and conformance with the design criteria.INTRODUCTIONThe regular grid of surface streets within San Francisco’s South of Market (SOMA) district provides little evidence of the geotechnical complexities that lie below. In the late 1800s, sand dunes, bedrock hills, cliffs, marshes, and mud flats were flattened and filled, concealing their locations and characteristics. The 1906 San Francisco earthquake and fire leveled many buildings in SOMA; new buildings were built after 1906 – often on top of rubble and debris from the structures that came before. Locally, the combination of natural geology and historical interventions can produce complex subsurface conditions that vary dramatically over short distances. This is particularly true at locations where tidal mudflats once met bedrock hills at the shore of San Francisco Bay.This case study describes an integrated foundation and ground improvement system implemented for a multistory “Class A” office building at a complex SOMA urban infill site. The system utilizes cement deep soil mixing (DSM) in combination with spread footings and micropiles to address a range of design and construction issues, including liquefaction and lateral spreading mitigation; consistency of earthquake ground motions; shallow foundation support; seismic uplift resistance; and avoidance of loading adjacent basement walls. The system was implemented by a technically-sophisticated owner through a process that included constructive collaborations between the project geotechnical engineer, structural engineer, general contractor, and specialty foundation and ground improvement contractor(s). The system is designed to cost-effectively provide a high level of seismic performance."

Jan 1, 2017

By Wu Jian-tao, LI Guo-wei

"The Cement Mixing Pile (CMP) quality assurance assessment is an important programme in evaluating the efficiency of foundation improvement. Coring is the current specified method of quality assessment in China which has the shortcomings of long cycle, high cost and low efficiency. The field and laboratory test show that the regular cone penetration test can only detect maximum of 4m of effective detection depth in CMP. In contrast, the method of cone penetration test in the reserved hole can detect the quality continuously along the pile at any depth. The tip resistance of reserved hole penetration in the 7th day has good linear relationship with unconfined compressive strength in the 28th day. The slope of linear relationship decreases with the increasing of clay particles content.INTRODUCTIONThe method of Cement Mixing Pile (CMP) is often used to improve soft soil foundation in highway construction, with the major purpose of reducing settlements under embankments (Bruce et al., 2000),which is a form of what is known as the Deep Mixing Method (Bruce et al., 2013). The CMP technology spread quickly in China in the 1980s. CMP quality assurance assessment is an important programme in evaluating the efficiency of foundation improvement. Coring is the current specified method of quality assessment in China (China Academy Of Building Research, 2002). The method of Coring is perceived in some quarters that samples will provide lower strengths given the distress caused to the core during drilling and extraction (Bruce et al., 2002).The cone penetration test CPT can provide continuous measurements of the penetration resistance, sleeve friction at the tip of the probe, which has advantages of simple operation, low cost and high efficiency compared with coring. However, CPT tests have not been established to assess CMP in Sweden because of difficulties in maintaining verticality (Larsson, 2005). In Finland and Norway, however, CPT tests are commonly used (Halkola, 1999). One of the disadvantages of CPT is the tendency of the cone to steer out of the column (Porbaha et al., 2003). Darya Mokrousova (2010) states this tendency to deviate can be overcome by pre-boring and starting the penetration test from the base of the pre-bored hole. Sheng Haiyang (1999) found that probes may be deflected out, sometimes even at small penetration depths, and may not give a complete inspection of the pile. Liu Songyu et al. (2003) suggested that the Standard Penetration Test (SPT) is an effective way to evaluate the strength and quality of stabilized soil-cement columns. In general, Regular CPT can’t test the full length of CMP, and SPT still needed drilling which causes discontinuous detection. From the existing standard of China, core sampling compressive strength test is the main method, evidently, coring displays a longer test cycle, high cost and low efficiency. Therefore, an improvement of CMP quality assessment, by conjuring a fast and reliable detection and evaluation method, is necessary. The aim of this paper is to research the feasibility of using CPT in assessing the quality of CMP and presents an improved CPT method."

Jan 1, 2015

By Axel J. Pollak

Since the late 1960's the Interstate Division for Baltimore City (IDBC) has been planning and developing the Interstate Highway System for the city to meet regional planning goals. The principal goals are to provide convenient access to the central business district and the port while diverting through traffic away from these congested areas. Interstate Route 95, an eight-lane highway carrying north-south traffic, has headed the city's priority list; during the 1970's its construction proceeded steadily from both east and west towards the harbor. Closing the final 8800-ft (2670-m) gap under the harbor will complete Interstate 95's construction. This final portion, known as the Ft. McHenry Tunnel project, will be built in nine construction contracts. Construction costs of the complete project are expected to exceed $700 million, making it the costliest single project in the Interstate Highway System. Full funding is being provided initially by the Federal Highway Administration (FHWA), and the Maryland Department of Transportation will re-pay the 10 percent local share from toll receipts within the first three years of operation.

Jan 1, 1989

By Matthias Pulsfort, Hanna Nissen, Markus Herten

An insufficient integrity of cast in-situ bored piles can lead to a reduction of the load bearing capacity and may require cost intensive repairs. Reasons for an insufficient pile integrity are linked to the construction process, mainly to poor concrete quality leading to bleeding and segregation of the fresh concrete. Moreover, the entrapment of soil and an insufficient concrete cover can pose a problem. Knowledge about the time-dependent development of the fresh concrete pressure during the construction process of bored piles is needed for a better understanding of the underlying processes causing these defects. Therefore, pressure measurements were carried out on different construction sites with pressure cells being installed at different depths along the reinforcement cage. The measurements revealed the maximum pressure acting on the surrounding soil. The achievement is a better understanding of the effects of the concrete placement specifically and the construction process in general on the surrounding soil to reduce the risk of pile imperfections.

Sep 8, 2021

By Luca Pingue, Regine Jagow-Klaff, Franco Muratore, Carlandrea Albonico, Damiano Frontini, Rudolf Wernecké

This paper describes an artificial ground freezing (AGF) application carried out to ensure both watertightness and structural support for the safe excavation of four cross passages of the Forrestfield Airport Link (FAL) project in Perth. The line will deliver 8.5 km extension of the existing urban rail network connecting the growing eastern suburbs of Perth with the existing suburban rail network. The proposed soil improvement technique is adopted as a smart alternative to jet grouting from the surface since the use of heavy equipment with long vertical mast was not allowed due to the line underpassing an airport in operation. In this paper, details of the challenges and lessons learned during both design and construction phases are given. Furthermore, it is described the geometry and the installation of freeze pipes in presence of a massive steel frame, ventilation system and slurry pipes of the tunnel boring machine (TBM) in operation. It is also illustrated the web monitoring system to allow key personnel to follow in real time the development of soil temperatures, tunnel convergences and ground surface deformations as well as changes in the interaction between international parties involved due to the COVID-19 pandemic.

May 1, 2022

By Ross T. McGillivray, David S. Graham, Dan A. Brown, Steven D. Dapp

"The Selmon Expressway includes an elevated structure extending across several miles of weathered karstic limestone geology, and represents a challenge for design because of the high variability of the material and the difficulty in characterizing the strength. The nature of the epikarst in this region of Tampa is such that variability can be extreme within distances of only a few feet. The weathered rock includes extremely soft soil infill within solution features on and within the formation. The limestone is so weathered that coring typically does not yield useful samples for strength testing, and in-situ Standard Penetration Testing (SPT) tests often encounter refusal blow counts. Thus the challenge for foundation design includes two components of reliability risks: the uncertainty associated with the ground conditions at a given foundation location plus the uncertainty associated with the foundation performance at a given location even when the stratigraphy is determined.This paper describes the design approach that has been implemented successfully for two projects at the Lee Roy Selmon Crosstown Expressway (LRS) in Tampa, Florida: the assessment and remediation of the reversible elevated lane (REL) foundations constructed in 2004, and the elevated expressways widening project constructed in 2012. Included in this design approach is a method developed for computing axial resistance in this local geology. Design for axial loading relies primarily on the development of side resistance, which was considered less subject to performance risks than base resistance. The calculation method incorporates a statistical analysis of SPT data, tempered by engineering judgment, to characterize stratigraphy at a given location into either soil, intermediate geomaterial (IGM) or rock.IntroductionThe subsurface stratigraphy of sites underlain by weathered limestone formations can be highly variable with respect to material layer thicknesses and strengths, even over short horizontal distances. This is the case for much of Florida, and particularly the Tampa area. These conditions present a challenging environment for the design of drilled foundations because of the need for a reliable determination of subsurface conditions at each foundation location, as they relate to the expected axial performance. Contributing factors include:"

Jan 1, 2015

By David Pierce

The Port of Seattle, one of the largest on the west coast of North America, made a strong statement regarding their support for reusing existing structures when a decision was made to rehabilitate Pier 69, on Seattle's downtown waterfront, for their new headquarters. Because of its age and location, the pier provided an unusual challenge to the Port and its consultants. The Port hired Peratrovich, Nottingham, and Drage Inc. to design the seismic strengthening of the pier itself. To remedy the lack of seismic resistance in the 70-year-old pier, PN&D designed a new steel-pipe-pile supported concrete apron next to it. The structure relied on a development by PN&D, the "spin-fin pile", to achieve the tension capacities required of the batter piles. The construction of this apron was completed in October of 1991. Another team of consultants performed the superstructure renovation design, which is now under construction.

Jan 1, 1992

By A. David Miller, Chika Oya

"Field sampling and testing are part of the Quality Assurance/Quality Control (QA/QC) requirements for all Cement Deep Soil Mixing (CDSM) Projects. Field sampling and testing are also used for determining the performance and quality of soil mixing method(s) and are the primary basis for accepting or rejecting the soil mixing wall among all other QC testing. Two of the most commonly recognized and used sampling methods for CDSM walls are wet grab sampling and verification coring. Depending on the types of wall construction and project budget, one or both of these methods are normally used to help evaluate the in-situ matrix and quality of the mixed soils. Additional to ASTM strength and permeability testing from wet grab sampling and verification coring, more and more testing methods are being employed and accepted. However, these other testing methods tend to be unnecessary, lack consistency and repeatability, and are more subjective to manipulation and interpretation. In certain projects, there are also misconceptions involved with the results of wet grab sampling and verification coring, hence it is important to note how these wet grab sampling and verification coring work and represent the work in terms of quality of production.TYPES OF PROJECTSCDSM projects include (but not limited to) in-situ stabilization, liquefaction mitigation, excavation support, groundwater cutoff, and pollution containment. Although these projects use similar equipment on the jobsites, each project is treated differently in terms of catering to specification, uses of different mix designs, and emphasis on certain steps during production.Different types of projects with different specification changes the focus of quality, but soil types in jobsite also determine how to proceed with production. For example, a jobsite with predominate gravel layer must be treated differently as opposed to jobsite with clayey sand as the main soil type.WET GRAB SAMPLEWet grab sampling is one of the most used testing methods for QA/QC. The wet grab sample specimen is retrieved right after finishing the production of the desired element.Wet grab sampling equipment consist the use of 28 cubic inch (458.84 cubic cm) box attached directly to one of the auger stems. Hinges attached to the top and bottom of the box is fabricated to allow collection only during auger withdrawal. The collection box is strapped just above the mixing paddles on the auger stem and measured from the center auger head tip to confirm proper depth of collection. This box method has been used in Japan and U.S. for numerous projects."

Jan 1, 2017

By Louay Owaidat, Daniel Jabbour, Allan Frappier, Jose Gomez, Mark Stanley, Tino Maestas

The U.S. Army Corps of Engineers (USACE) is implementing a levee strengthening program along the Sacramento River East Levee (SREL) designed to correct 11 miles of deficient levees as identified by recent hydraulic and geotechnical investigations. The first project, the subject of this paper, completed in 2020 resulted in approximately 3.0 miles of improvements to the California Central Valley Flood Protection system. The project area lies along the east bank of the Sacramento River in Sacramento. The program consists of constructing cutoff walls through existing levee embankments to remediate levee through seepage and under-seepage. Key challenges included designing and constructing measures to remediate a 100-year-old legacy levee system, the presence of both industrial and residential properties immediately adjacent to the landside of the levee creating severe space and access limitations, and performing this work during the 2020 statewide mandate to shelter-in-place due to the COVID-19 pandemic. The project team of contractors, USACE, state and local agencies, and engineering firms partnered to bring this project to successful completion within budget and on schedule expending more than 60,000 man-hours with no lost time accidents. With the issuance of future planned contracts, the program will significantly reduce flood risk to the City of Sacramento.

Sep 8, 2021

By Dominic Parmantier, Jason Page

"In the past, the designers of DSM have analyzed various failure modes and then specified a minimum unconfined compressive strength (UCS) for the soil-cement. The specified minimum UCS reflected the compressive stress in the soil-cement under design loads and an appropriate factor of safety. With the increased use of finite element analysis for the design of DSM applications where allowable strain as well as stress are considered, there is a growing trend for designers to specify a modulus and occasionally a tensile strength for the soil-cement in addition to the UCS. This paper compares the relationship of modulus and tensile strength to UCS for soil-cement from a recent DSM project with unique testing requirements. These results are compared to published data. The case is made that designers should utilize published relationships to characterize the required strength and stiffness by a single acceptance criterion: UCS.INTRODUCTIONAs the use of DSM has increased in popularity so has the use of service state deformation analysis in lieu of more traditional failure mode analysis. Most DSM designers are interested in the appropriate modulus values and occasionally tensile strength values of soil-cement as well as simply the unconfined compressive strength (UCS) of soil-cement.Although there are numerous published correlations between the UCS, tensile strength and modulus of soil-cement, some DSM project specifications are produced which have acceptance values for tensile strength, modulus, and UCS. If this specification of multiple strength properties is consistent with the nature of soil-cement, then there is really no harm except for the expenditure of client money on unnecessary testing. If however the multiple strength properties specified are inconsistent with the material properties of soil-cement, then the specifications can create the expectation that the DSM contractor can somehow create a custom soil-cement with tensile strengths and modulus characteristics which are unachievable.This paper presents a brief summary of a project in Burnaby, B.C. which specified minimum values for the tensile strength, modulus, and UCS of the soil-cement. A comparison of those test results to published correlations between the UCS and the tensile strength is presented. Additionally, a comparison of modulus derived from two different methods of testing is presented along with a comparison to published correlations between UCS and modulus for soil-cement."

Jan 1, 2015

By Brandon Smith, William Bohlen

Riverbank erosion along the Brazos River has modified the structural support conditions for an existing bridge structure in Southeast Texas. The 8-span, 1,200-foot long bridge was completed in 1992 along Highway 99, a key corridor for the Houston area. Foundation support conditions have been altered due to natural, ongoing river morphology for three bents on the affected riverbank. Recent events include three storms within a three-year period that each exceeded the 500-year return probability. This resulted in accelerated erosion along the northern riverbank. Over forty vertical feet of soil has been removed in some locations. Drilled shaft foundations are now functioning as columns. This review considers the behavior of columns and deep foundation elements due to the modified support conditions. The review ultimately presents a rational methodology for the review of the present and anticipated future bridge configuration with respect to current strength, service, and extreme event limits, with corresponding safety factors for the design. Introduction and Background The Fort Bend Grand Parkway Toll Road Authority (Owner) oversees the State Highway 99 Judge Jodie Stavinoha Bridge over the Brazos River. The 8-span, 1,200-foot long bridge was originally designed with four southern approach spans of 115 feet; a three-span continuous river crossing with span lengths of 195 feet-235 feet-195 feet; and a single northern approach span of 115 feet. Figure 1 provides an overview of the northern portion of the bridge. Table 1 provides a summary of the original bridge substructure configuration. When the bridge was completed, the centerline of the Brazos River was located at midpsan of the main span and the northern high bank was originally located at Bent 7. Erosion process has forced the northern high bank to Abutment 9 (also called Bent 9), and the river centerline during normal flow conditions is located south of Bent 8. The overall estimated river excursion at present day is approximately 270 feet to the north from its original location. An erosion wall that was installed in 2017 limits further erosion of the north river bank within the 300-foot width of the roadway corridor right-of-way. This study was developed to better understand the existing conditions, and to forecast the need, nature, and criteria for potential future improvements.

Jan 1, 2019

By Paolo Cavalcoli, Federico Pagliacci, Marco Chiarabelli

"The Sheikh Jaber Al-Ahmad Causeway Project in Kuwait is estimated at approximately $US3.7 billion and consists of constructing a causeway across the Kuwait Bay, connecting the Shuwaikh Port with the northern Subiyah area, where the new “Silk City” will be established. The $US77 billion Silk City will revive the ancient “Silk Road” trade route and will become a major free trade zone linking central Asia with Europe. The new city will be completed in 2030, it will house about 700,000 people and, furthermore, it will include the tallest tower in the world. The Causeway will stretch approximately 23.3 miles and will be composed of a combination of low-level bridges, embankments and transition islands. A bridge of about 16.8 miles in length will span the navigation channel and a free flow interchange at the Shuwaikh Port will connect the causeway to the main road network in Kuwait City. The geo-construction portion of the project involves the execution of 1,200 drilled shafts with diameters of 98 inches and 118 inches embedded to a maximum depth of about 276 feet. Details are provided concerning the subsurface conditions, the geotechnical characteristics and the strength parameters, illustrating, as well, the installation technique implemented for the construction of the drilled shafts. In addition, particular attention is paid to the description of the challenges faced while constructing the drilled shafts at a distance of about 10 miles from the shore, such as the depth of the water above the midline (more than 160 feet), an underwater current and the tidal variation.INTRODUCTIONThis paper presents an overview of the foundation works executed for a 37km causeway across the Bay of Kuwait, connecting Shuwaikh Port with Subiyah New Town Development. The project, in which Trevi is actively engaged, includes a 27 km low-level bridge across the bay, a main bridge with a span of 200 m, an overpass and a 5 km approach road onshore in Subiyah.The main purpose of this report is to provide information about the nature and features of the applied technique of bored piles, including a description of each work phase and other related details, in order to aid in the design of the foundations for the proposed construction.Works for the soil investigation were carried out in accordance with accepted geotechnical standards/guidelines. Brief descriptions of the methodology of the field are also provided in this report."

Jan 1, 2016

By Emad Farouz, Francis A. Abreu

"This paper presents a case history of a successful construction-phase pile load test program that optimized the pile design in challenging ground conditions at the Great Neck Wastewater Treatment Plant in the Town of North Hempstead in Nassau County, New York. The improvements and expansion of the wastewater treatment plant included the construction of several new structures to comply with new stringent nitrogen discharge requirements and new design flow. The challenging ground conditions included up to 20-ft thick organic deposits with weight of hammer blow counts and up to 14 percent organic content and tidal ground water that was near the ground surface. The foundation design evaluated various deep foundation alternatives and selected driven closed-ended pipe piles then filled with concrete as the most suitable foundation. The selection process included considerations of cost, risk, vibrations, noise, and schedule. The contract documents utilized an innovative approach of performing an optimization load test program that was implemented during construction to optimize pile lengths and reduce potential vibration and construction schedule.This paper discusses the details of the successful load test program including static testing, dynamic testing, and the innovative contracting approach utilized to implement the construction phase load test program. It also discusses the successful development and implementation of driving criteria for production piles and construction challenges. The successful load test program resulted in savings of several hundred thousand dollars, optimized schedule, and lower environmental impacts.SITE AND PROJECT DESCRIPTIONThe Great Neck Water Pollution Control District (GNWPCD), located in the Town of North Hempstead in Nassau, New York, owns and operates a municipal wastewater treatment plant (WWTP) that discharges treated effluent through an outfall to Manhasset Bay, which is a tributary of the Long Island Sound. The site is located west of Manhasset Bay and is surrounded on three sides by local roads, and commercial, industrial, and recreational properties. The site has a gentle slope ranging from elevation +20 to +7 from west to east, respectively, based on the Nassau County Datum.To comply with new nitrogen discharge requirements and new design flows, the GNWPCD contracted CH2M HILL, Inc. and William F. Cosulich Associates as a Joint- Venture (JV) to design and provide services during construction of eight new advanced nitrogen removal facilities."

Jan 1, 2017

By George Gazetas, Sissy Nikolaou, Fani Gelagoti, Irene Georgiou, Rallis Kourkoulis

"The need to shift geotechnical design from a “factor of safety” to a “performance based” design (PBD) approach has increased rapidly in the past years following examples from structural engineering. PBD supports sustainable engineered systems that target project-specific geotechnical behavior objectives and results in more rational and, in most cases, less conservative solutions. Resiliency, efficiency, risk optimization, and cost-effectiveness are key components of this approach. For design of retaining walls, the concept of mechanically stabilized earth (MSE) systems combines these attributes, while being environmentally friendly and adaptive to variable construction conditions. Natural hazards, such as earthquakes, may drive the design of MSE systems whose reliability depends on their performance under extreme events. In this paper, the authors compare the seismic response of an MSE steel-reinforced vs. concrete-reinforced retaining wall. The MSE system is composed of a grid of longitudinal and transverse ribs which internally enhances the capacity of the soil backfill. Results of fully non-linear twodimensional (2-D) numerical finite element analyses using two commercial programs with emphasis on the interface conditions are presented. The pull-out resistance of the grid used in the numerical simulation was evaluated from actual pull-out experiments. The results demonstrate a superior performance of the MSE system as compared to the concrete one, especially when subjected to strong seismic excitations.INTRODUCTIONThe idea of performance-based geotechnical engineering is not new, and has been evolving as our perception for ‘good’ performance has also evolved (Kramer, 2008). In early practice, the only criterion for achieving good performance was to avoid failure; designers had only to ensure that the available capacity of the geotechnical system is sufficiently higher than the expected demand (i.e. Load and Resistance Factor Methodologies). Yet, even when the key design requirements against collapse are satisfied, the system may still be placed into a condition in which the deformation constraints are not met (Bolton, 2012). To address these issues, geotechnical design has been developing into a predominantly performance-based approach that correlates deformation considerations to the severity of the experienced loading. As such, in earthquake-related problems, the definition of good performance of a geotechnical system is no more unique; for a low intensity earthquake the system should remain serviceable (i.e., the developed deformations should remain low), whilst for the design earthquake the maintenance of lifesafety is the single performance criterion."

Jan 1, 2016