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By Kevin P. Gleckler, Steven C. Highfill

"Escalators to access platforms for the Second Avenue Subway Station at 72nd Street in Manhattan are to be installed in the basement of an existing 19-Story residential building. The escalators, which extend below the existing building foundations, require excavation of an inclined rock cavern up to 80-feet deep. Underpinning of columns within the 19-story building as well as a stone masonry party wall and columns for an adjacent 5-story building was completed prior to excavation of the rock cavern to ensure structural stability.This paper will discuss the analysis and design of the underpinning system, the installation and load transfer procedures and the cavern excavation immediately below. The underpinning system was subject to very strict deformation limits and to electronic monitoring prior to and throughout the load transfer and construction process. Key details such as the load transfer mechanism between the reinforced concrete column and the temporary structural steel underpinning frame will be discussed. The challenging rock excavation process will be described which utilized conventional equipment and pattern drilling with Damite rock splitting mortar.INTRODUCTIONPhase 1 of the Second Avenue Subway is being built by MTA Capital Construction (MTACC) to improve subway service on the east side of Manhattan. Entrance 1 for the 72nd Street Station of the Second Avenue Subway is located on the east side of 2nd Avenue at the corner of E 69th Street in New York City. Access to the station mezzanine, approximately 80-feet below grade, is designed to be routed through the basement of an existing 19-story residential building. From the sidewalk, stairs and escalators within the width of sidewalk connect the riding public to a basement level mezzanine, which turns into the building at roughly 16 feet below grade (Fig. 1). Riders then connect to three long escalators to arrive at the station mezzanine. The escalators are to be installed within an inclined and arched cast-in-place (CIP) concrete lined rock cavern (Fig. 2). Construction of both the entrance into the basement and the escalator cavern require the transfer of columns within the 19-story building. Excavation of the escalator cavern also impacts the foundation support for columns and a load bearing party wall for the 5-story residential building immediately to the north. Two stages of load transfer were used at each location. The Stage 1 transfer used a temporary underpinning system to unload the current structure which allowed for construction of the permanent transfer girders. Stage 2 transferred the load from the temporary system to the permanent transfer girders."

Jan 1, 2016

By Ricardo Dobry, Alain Pecker, George E. Leventis, Ralph B. Peck

"This year’s DFI Outstanding Project Award is for the design and construction of the foundation scheme for the largest cable-stayed bridge in the world. In 1993, Gefyra, SA (a French/Greek consortium led by VINCI of Paris, France) was awarded a €750 million ($1billion+ USD) Concession Contract to design, build, fi nance, operate and maintain a three-span cable-stayed suspension bridge connecting the Peloponnese, Greece’s southernmost peninsula, with the mainland across the Gulf of Corinth. The contract extends over a 42-year period, 7 years for design and construction and 35 years for operation. The project was fi nanced through a combination of public funds, private equity and bank loans. Alternative foundation concepts that were considered included traditional driven piles, deeply embedded caissons and soil improvement. PROJECT CHALLENGESThe extreme technical challenges faced included:??Weak foundation soils composed of soft alluvial deposits consisting of interbedded layers of granular and cohesive materials with thin layers and lenses of gravel and liquefi able sand pockets; rock is believed to be at a depth of 1,000 m (3,500 ft) or more.??A very deep seabed exceeding 60 m (200 ft).??The requirement to withstand the collision of 180,000-ton tankers traveling at 16 knots.??Maximum wind forces of 250 km/hour (155 mi/hour).??Design seismic forces corresponding to Richter magnitudes of 7.0+ with peak ground accelerations of 0.48 g at seabed.??Design tectonic movements of 2 m (7 ft) in any direction between any two adjacent bridge pier foundations/pylons.Considering subsurface conditions and local seismicity and water depths, foundation design and construction methods were the key drivers for this project. In large part, the success of the project is owed to the unprecedented partnering and collaboration between all partners involved fostered under the leadership of Jean Paul Teyssandier and Gilles De Maublanc of VINCI Group (France) who served as lead Concessionaire and General Contractor. The joint venture’s lead Greek partners were Elliniki Technodomiki/AKTOR and J&P/AVAX. Alain Pecker of Geodynamique et Structure (France) served as lead Geotechnical Consultant/ Designer while Buckland and Taylor (Canada) served as Design Checkers with Ralph Peck and Ricardo Dobry (U.S.) as Special Advisors on foundation issues, Langan International/Langan Engineering and Environmental Services P.C. (George E. Leventis, Gregory Biesiadecki and Diane Fiorelli) served as Technical Advisor on geotechnical, geodynamic and foundation/marine construction issues."

Jan 1, 2007

By Adnan A. Malik, Tadashi Maejima, Jiro Kuwano

"Previous studies revealed that the helix deflection reduced the end bearing capacity of screw pile in dense ground even if the installation process is completed with minimal soil disturbance. The ultimate end bearing capacity in dense ground is difficult to achieve during the full-scale pile load test due to the limitation of the loading system. Therefore, in the present study, model scale of testing is selected to investigate the effect of helix deflection on load settlement behavior of single helix screw pile under increasing stress level. It is observed from the test results that the applied surcharge pressure, which is used to simulate the effect of stress level, is decreased with increase in model ground thickness. This decrease in the stress level is due to the frictional resistance between the container wall and sand. It is also observed that the end bearing capacity of screw pile increases with the increase in stress level but at gradually decreasing rate. The test results indicated that the helix deflection during the pile load test should not be more than critical deflection (0.72 mm average) of the helix to avoid any reduction in the end bearing capacity of screw pile. The helix deflection, which is measured after the pile load tests are also compared with the equations of flat circular plate having uniformly distributed load over the plate with simply supported and fixed inner edges.INTRODUCTIONThe screw pile consists of a central steel shaft with one or more helices attached at different location on the central shaft. The installation mechanism of screw pile consists of torque and pushing force. The screw pile installation mechanism can affect the unit weight of the ground during its installation. This effect is small in cohesive soils but it is quite noticeable in loose to medium dense sands (Adams 2011; Santos et al. 2013). The pushing force should be controlled in such a manner that pile penetration should be at least 80% of the pitch of the helix, during each revolution (Perko, 2009)."

Jan 1, 2017

By Rajasekar Subbian, Jessica Oudhof

In the Netherlands pile foundation design is done using CPTs in accordance with EC7 national annexure. The capacity per tip level is calculated for every CPT followed by zonation to find the tip level per zone. The correlation factors are used to take into account the variability in ground across the zone and they depend upon the number CPTs within the zone. The CPTs and pile tip levels selection for zoning is an iterative process that can demand significant manual effort to produce an economical pile plan. This often leads to the use of conservative correlation factors in order to accelerate the design process. Thus, it has been automated in a tool with CPTs, pile location and loads, and capacities as input. The tool has also been employed in two case studies and the results are compared to the current design practise.

May 1, 2022

By Kalyani Devabhaktuni, Mike Minton, Mark T. Howe, Yan Zhang

During the procurement phase of a Design-Build (DB) project, design-build contractors must often commit to a fixed price based on limited or incomplete geotechnical information. This lack of information can result in an inaccurate assessment and allocation of project risk to either the contracting authority or the DB contractor. This paper presents a case study of an elevated water tank supported by mixed ground improvement techniques, including Vibro-Compaction (VC), Aggregate Piers (AP) and Compaction Grouting (CG) in East St. Louis, Illinois. An adaptive design and contracting approach provided the best value solution for a complicated set of geotechnical problems, including static bearing capacity and settlement concerns as well as liquefaction induced settlement. Close cooperation between the owner, the tank contractor, the geotechnical engineer and the ground improvement contractor was essential to produce an effective solution. Ground Improvement techniques resolved the geotechnical challenges at the site through adaptive design methods, utilizing progressive rounds of verification and real time data acquisition to achieve performance objectives. This paper details the evaluation of geotechnical criteria, the selection of ground improvement techniques, the adaptive design and implementation of ground improvements, as well as contracting methodologies used to ensure that the best value was provided. PROJECT INFORMATION In November, 2016, CB&I Storage Tank Solutions (McDermott) submitted a design/build proposal for an elevated water tank for Illinois American Water Company (IAW) in East St. Louis, Illinois. The purpose of this tank was to have backup water capacity for power generation. In the RFP, IAW requested two alternate styles of tank: Option 1, a 1250 Million Gallon (MG) Composite Elevated Tank or Option 2, a 1250 MG Waterspheroid tank. Option 1 consisted of a steel tank supported on a concrete tower. Option 2 consisted of a steel tank supported on a steel shaft. The height (determined by IAW) was 140 feet to the top capacity line measured from top of floor slab.

Jan 1, 2019

By Jon Huff, Jeffrey Donville, Hannah Iezzoni, Dan Stevenson

Occasionally, in the design of deep foundations for a structure, a single deep foundation element may be used to support a building column. The most common type of element used in such cases is a drilled shaft (also referred to as a drilled pier, caisson, or bored pile). However, as installation capabilities have improved, large diameter augercast piles are increasingly more common. While drilled shafts and augercast piles differ significantly in construction methods, in the eyes of the International Building Code (IBC), both are treated as cast-in-place deep foundations and must comply with many of the same code provisions. Deep foundations are required to be braced such that lateral stability is provided in all directions, however isolated, cast-in-place elements that have a diameter (D) of at least 2-feet and a length (L) not more than 12 times the diameter can be an exception. In response to the concerns raised by some member professionals, the Deep Foundations Institute’s (DFI) Augered Cast-in-Place Pile and Drilled Displacement Pile Committee took a closer look at the code and its applications, the historical development of the code language through the years and performed analytical modeling to evaluate the impact of this ratio on a pile’s stability. The question is whether the limiting ratio included in the IBC 2018 code provisions is justified, or whether different criteria should be used to determine when isolated deep foundation members are allowed.

Sep 8, 2021

By Robert F. Stevens, Robin Givet, Kenneth Viking

"Summary This paper describes a case of a directional pile installation conducted from an existing oil platform in the Caspian Sea, offshore Baku. Results are presented for 660 mm outer diameter (660 mm OD) conductor piles. Each conductor was equipped with a beveled aluminum toe for directional impact driving and was driven through a 710 mm casing using a Delmag 100–13 diesel hammer and a chaser pile. The 710 mm casings were preinstalled to a depth of 75 m below mud line (75 m BML). The longest impact driven conductor pile on the project was 456 m at end of drive, and reached the terminal depth of 295 m BML.Soil conditions consisted of soft to stiff silty clay to a depth of 30 m BML, underlain by stiff clay to 96 m BML, very stiff silty clay to 200 m BML, and very stiff to hard clay down to 300 m BML.In order to assess the maximum stresses in the conductors and check the performance of the hammer, the driving of each conductor was monitored using a Pile Driving Analyzer (PDA). The hammer fuel setting was adjusted based on the PDA outputs to ensure the conductors were not overstressed during installation. All driving and monitoring operations were carried out from the drill floor.The conductor piles drove easier than anticipated but in the direction predefined by the pre-cut angle of the beveled aluminum toe. The driving system performance was good. Post driving, the SRD were analyzed by either the global method analysis, using WEAP, or by the CAPWAP program.To detect any collision between the conductor being driven and the adjacent wells in production, the well heads were monitored in real time with high sensitivity accelerometers. These accelerometers were connected to an alarm system on the drill floor, triggering a siren and a strobe light should a collision be detected by an abnormal increase of the peak acceleration.IntroductionThe world longest directional impact driven pile was installed in year 2005. The operation was carried out from an offshore production, drilling, and quarters (PDQ) platform located about 120 km east of Baku, in the Caspian Sea.The platform foundation consists of driven piles and 24 slots were available for drilling the wells to the reservoir, located about 3800 m below sea floor. Each slot was fitted with a casing, 710 mm in diameter, running from the top of the jacket to a depth of about 75 m BML (Figure 1). Oil production started in 1997 and by the end of 2003, 14 wells were in operation; 10 slots were therefore still available, either for oil production or for water injection. However, due to larger than expected settlement of the platform, drilling of additional wells was put on hold. After further investigation, experts concluded the settlement was due to an alteration in the mechanical properties of the bearing strata supporting the foundation piles. This alteration was due to either excess soil material transportation, or soil fracture by the drilling fluids (mud), when drilling the first wells. With only 14 wells in production, out of 24 possible, the owner faced a new dilemma: to drill, or not to drill new wells?"

Jan 1, 2014

By Tian Miaomiao, Cheng Yin, Shen Jun, Yu Hao, Li Yafei

Vast amounts of waste drilling mud containing heavy metals is produced during oil drilling process, which causes great pollution to the environment. Therefore, it needs to be treated until it is harmless. This study uses industrial waste and Portland Cement stabilized waste drilling mud; the unconfined compression strength, leaching amount of Pb2+ and Cr6+ ions, and pore size of the stabilized soil were tested at different times during freezing-thawing cycles. The antifreeze performance of the stabilized drilling mud with industrial waste is discussed. The results show that the strength of the stabilized soil decreases with an increase in the number of freeze–thaw cycles. The strength loss of the stabilized soil after freeze–thaw cycles can be effectively reduced by increasing the industrial waste content, especially the content of phosphogypsum in the stabilizer component. Pb2+ ions and Cr6+ ions can be effectively stabilized by industrial waste. The results of the pores test prove that the compactness of stabilized soil solidified by industrial waste residue is greater than that of cement alone.

Nov 1, 2022

By Anahita Modiriasari, Benjamin S. Rivers

Measurement while drilling (MWD) is a subsurface exploration technique associated with real-time and continuous monitoring and recording of drilling data during the drilling process. This technique can be used for underground investigations to differentiate ground strata, detect the presence of fractures and voids, and evaluate geological features and mechanical properties of geomaterial. When MWD is used for geotechnical investigations, it can improve site characterization, identify variable conditions, improve design and construction, lead to shorter project delivery times, reduce the cost and risks associated with limited subsurface data and geotechnical uncertainties, and maximum return-on-investment. Given these benefits, MWD is gaining attention among transportation agencies and the geotechnical industry. Federal Highway Administration’s (FHWA’s) innovation deployment program “Every Day Counts (EDC-5)” includes the implementation of Advanced Geotechnical Methods in Exploration (A-GaME), which aims to implement effective, underutilized subsurface exploration methods, including MWD, in U.S. practice. This paper provides an overview of the MWD technology for geotechnical site investigations and presents a case history where MWD was employed to design deep foundation for the construction of a building in Massachusetts. The advantages of this technology for risk reduction and project cost and time saving are also discussed.

Oct 1, 2022

By Manchanda H, Agarwal J.

The construction industry has one of the largest numbers of injuries compared to other industries. Thus, reducing accidents and determining construction risks are extremely important. One of the essential steps for construction safety management is hazard identification and risk assessment, since the most unmanageable risks are from unidentified hazards. While the urban rail transit systems are being developed rapidly in almost all major cities of India, adjoining Existing Building Structures and historic sites are facing possible threats of unexpected damages and accidents. The protection of these structures becomes one of the major challenges specifically when the infrastructure being developed involves construction of underground tunnels passing through old cities. The assessment of settlement induced damage on buildings during the preliminary phase of tunnel excavation projects, is nowadays receiving greater attention. Analyses at different levels of detail are performed on the surface building in proximity to the tunnel, to evaluate the risk of structural damage and the need of mitigation measures. The current paper presents current practices being adopted in India for prediction and excavation of tunnelling induced ground movement and building damage risk-assessment. The paper highlights empirical and numerical approaches towards predicting settlement induced damages on buildings during the tunnelling, detailed step by step methodologies for conducting building condition surveys, evaluating associated hazards, and adopting adequate building risk identification and mitigation methods. The paper also discusses associated technical and contractual challenges and highlights way forward to overcome them.

Sep 1, 2022

By Mohamed Mekkawy, William W. Wheaton, Ira Brotman

"The Virginia Port Authority and the U.S. Army Corps of Engineers are partnering to construct the Craney Island Eastward Expansion (CIEE) to meet the dual purpose of extending the life of Craney Island as a dredged material management area and providing land for a state-of-the-art marine terminal. The over 500-acre (200-hectare) expansion provides additional upland dredged material capacity for the Hampton Roads Harbor by constructing perimeter dikes, that once filled, will provide land for the development of a container terminal. In the winter of 2010/2011 the first stage of sand fill was placed, followed by the installation of approximately 12 million linear feet (MLF) (3.6 million linear meters, MLM) of marine PVDs. With over 36 MLF (10.9 MLM) of PVD required to complete dike construction the project will be one of the largest PVD installation project in the U.S.This paper details the challenges associated with the construction of the cross dikes, in particular the design, testing, installation and monitoring of prefabricated vertical drains (PVDs) installed overwater to depths of over 130 feet (40 meters) for foundation improvement in the insitu very soft Norfolk Clay. With expected settlements of 20–30 ft (7-10 m) and 30 percent average strains, the discharge capacity of the PVDs was of particular concern. Laboratory data is presented showing the magnitudes and variability of discharge capacity under different confining pressures in both a straight and buckled condition.The method of installation and monitoring of the marine PVDs in open water included developing a specialized barge and sophisticated positioning and data collection system to verify installation location, depth of penetration and track quantities. An observational method, including material testing, detailed surveys, periodic in-situ testing, and instrumentation, was utilized by the project team to assess the project’s progress and allow for validation of consolidation and strength gain rates and magnitudes."

Jan 1, 2017

By Ira Brotman

The Virginia Port Authority and the U.S. Army Corps of Engineers are partnering to construct the Craney Island Eastward Expansion (CIEE) to meet the dual purpose of extending the life of Craney Island as a dredged material management area and providing land for a state-of-the-art marine terminal. The over 500-acre (200-hectare) expansion provides additional upland dredged material capacity for the Hampton Roads Harbor by constructing perimeter dikes, that once filled, will provide land for the development of a container terminal. In the winter of 2010/2011 the first stage of sand fill was placed, followed by the installation of approximately 12 million linear feet (MLF) (3.6 million linear meters, MLM) of marine PVDs. With over 36 MLF (10.9 MLM) of PVD required to complete dike construction the project will be one of the largest PVD installation project in the U.S. his paper details the challenges associated with the construction of the cross dikes, in particular the design, testing, installation and monitoring of prefabricated vertical drains (PVDs) installed overwater to depths of over 130 feet (40 meters) for foundation improvement in the insitu very soft Norfolk Clay. With expected settlements of 20?30 ft (7-10 m) and 30 percent average strains, the discharge capacity of the PVDs was of particular concern. Laboratory data is presented showing the magnitudes and variability of discharge capacity under different confining pressures in both a straight and buckled condition. The method of installation and monitoring of the marine PVDs in open water included developing a specialized barge and sophisticated positioning and data collection system to verify installation location, depth of penetration and track quantities. An observational method, including material testing, detailed surveys, periodic in-situ testing, and instrumentation, was utilized by the project team to assess the project?s progress and allow for validation of consolidation and strength gain rates and magnitudes.

By Nadir Ansari, Brian W. Wilson, Marina S. W. Li

"A hybrid Deep Mixing (DM) shoring system was recently constructed for a high-rise development in downtown Vancouver, British Columbia, Canada for the temporary support of a five-level basement excavation. The site is bounded by an existing bridge off-ramp structure along its longest side and by city streets on the other two sides, which formed a truncated triangle in plan. A conventional secant pile wall was installed along the longest side, about 380 ft (116 m) in length, of the site. Hybrid shoring walls (HSW) 1 and 2 were installed along two shorter sides with each being 235 to 246 ft (72 to 75 m) long. HSW 3 completed the excavation support system along the shortest side with a length of about 55 ft (17 m). Cutter soil mixing (CSM) was proposed by the excavation and shoring design-build team in lieu of conventional secant piling. CSM was the preferred method to construct the infill panels between soldier piles because of the speed at which the shoring system could be constructed in the variable fill, peat, wood waste and overburden. Design ConsiderationsTo minimize the impact on buried utilities along the outside perimeter of the excavation, the temporary shoring was designed to limit the lateral displacements to less than 0.8 in (20 mm). Factors taken into consideration for shoring design included the lateral earth pressures from the fill and native soils, groundwater pressures, temporary construction loads (e.g., crane or heavy plant/equipment), and permanent structural requirements. The subsurface conditions at this site typically consisted of fill (cohesive and granular), overlying peat and/or wood waste, overlying clayey silt to sandy silt, overlying weathered to dense to very dense clayey silt till to sandy silt till with silt layers. Localized, perched groundwater was observed within the fill, peat, wood waste and sandy silt layers above the dense till."

Jan 1, 2017

By Keith MacKay, John Carter, David Siddle, Fernando Faminia

"The River Green Residential development, is located in the municipality of Richmond, BC adjacent to the Fraser River. Ground conditions at the site consisted of medium to fine grained alluvial sands and a high groundwater elevation. A temporary low permeability retaining wall was required in order to facilitate the construction of an underground parking structure without inducing settlement of adjacent structures, which include the Richmond Olympic Oval; part of the legacy of the Vancouver 2010 Winter Olympics. Golder Associates Ltd. and GeoPacific Consultants Ltd. utilized Cutter Soil Mixing (CSM) technology to enable construction of a continuous combined low permeability cut-off and retaining wall around the perimeter of the property. The 350m long wall was keyed into marine clay at a depth of 28m below ground surface, and contained H-Pile reinforcement installed at regular intervals. The CSM technology provided many benefits for this project, allowing the combined cut-off and retaining wall to be constructed within a very narrow footprint (650mm width). The low noise impact and near vibration free construction of the CSM equipment provided minimal inconvenience to nearby stakeholders during construction. To reduce dewatering volumes during excavation and prevent significant water-table drawdown the Hydraulic Conductivity requirements for the wall were 1 x 10-7 cm/s or less. Project specifications called for a different strength requirement for upper and lower portions of the wall. The top 13 meters of the wall required an Unconfined Compressive Strength (UCS) of 4MPa to act as a retaining and cut-off wall, whereas the bottom 15 meters of the wall required a UCS of only 0.5 MPa to act only as a cut-off wall. Wet-grab and core samples were obtained from the panels to confirm the UCS and Hydraulic Conductivity specifications were met.INTRODUCTIONGolder Construction Inc. and GeoPacific Consultants Ltd. conducted the design and construction of a deep soil mixed cut-off and retaining wall system. The “dry-box” solution was used to surround the excavation of an underground parkade and prevent flows of groundwater into the excavation."

Jan 1, 2016

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

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

Oct 1, 2022

By George Burnhart

"Sonic drilling is a relatively new technology even though it has been in development since the late 1940s. It was initially funded by the U.S. petroleum industry and then, in the late 40s, Russian scientists worked on developing sonic drilling, their interest based on drilling rates 3 to 20 times that of conventional methods. In the early 1960s, the Shell Oil Company backed research that resulted in a down-hole device with a series of eccentric weights driven by drilling fluid to generate vibration. Hawker Sidley, in the early 1980s, developed the first modern prototype sonic drills in Vancouver B.C. and the North Star Drilling Company in Minnesota became the first contractor in the U.S. to operate sonic equipment in 1985. In 1994, North Star became a division of Boart Longyear, headquartered in Salt Lake City, Utah.What’s Unique about a Sonic DrillA sonic drill rig appears and operates very much like any conventional top-drive rotary rig. The key difference is that a sonic drill has a specially designed hydraulically powered drill head, containing oscillators, that generates adjustable high-frequency vibratory forces. The sonic head is attached directly to the drill pipe or outer casing, sending the high frequency vibrations down through the drill steel to the face of the drill bit. This creates displacement, fracturing or shearing action depending on the material being drilled. The oscillator uses two eccentric, counter-rotating balance weights or rollers that are timed to direct 100% of the vibration at 0 degrees and 180 degrees. An air spring houses the oscillators and separates the vibration from the drill rig itself. The vibratory frequency is controlled to suit operating conditions and to achieve optimum drilling rates.When the vibrations coincide with the natural resonant frequency of the steel drill rod or casing, a natural phenomenon called “resonance” occurs. It allows the rig to transfer timed vibratory energy into the top of the drill string, utilizing the natural stored energy of the steel. This causes the drill string to use inertia and act like a flywheel delivering tremendous amounts of energy directly to the bit face. In friendly overburden formations, a sonic drill rig can achieve penetration rates of one ft per second."

Jan 1, 2008

By Andrew McNamara, Stuart Norman, Matthew Dearing, Michael Pelken, Asha Panchal

The deep foundations industry has largely remained unchanged since in the advent of CFA piling in the 1960s. Piles have consequently been designed and constructed following the traditional codes and standards without much regard for optimising in-life efficiency or end-of-life reuse. After existing developments have been demolished there is little motivation to reuse existing piled foundations as their load bearing capacity and structural integrity cannot be verified. Therefore piling contractors are increasingly spending more resources on coring through existing piles, only to be replaced with larger diameter or deeper piles. The hollow element of the HIPER® Pile provides access to the entire length of the pile to permit inspections and a shaft in which the pile can be extended if needed. This paper presents and compares the embodied carbon savings, both during construction and through foundation reuse, from a HIPER® Pile scheme compared with the traditional solid pile scheme. A discussion on the benefits of this technology and its implications on warranties and approvals is also presented to motivate the foundations industry to embrace whole lifecycle assessments and support the journey to net-zero carbon.

May 1, 2022

By N. Schmitz

This paper explains how new digital solutions improve reverse circulation drilling operations. Upgrading field-proven reverse circulation drilling (RCD) rigs with new digital technologies enables semiautomated drilling, with upgrade options for fully automated & remote drilling. Key elements of the improvements are electrically controlled valve systems, process instrumentations, a state of the art machine controller and drilling operation via a touch control panel. Automation of core processes, such as adding drill pipes, reduces set-up times, increases machine uptime for drilling and as a result efficiency. While drilling, sensors provide continuous feedback, which is used to automatically adjust e.g. the weight on bit to the optimum; resulting in an increased rate of penetration and less wear and tear. While in the past hydraulic power packs (HPU) have typically been operated at a constant high-performance level with related high fuel consumption, a new interface between the machine controller and the power unit regulates the HPU performance exactly according to the actual drilling operation needs. This leads to significant fuel consumption reduction. The safety benefits of the digital improvements are the ability to remotely operate the rig in challenging site conditions via a mobile operator panel.

Sep 8, 2021

By Akhila Manne, Prasad P. V S R

Storage tanks are heavily loaded thin-shelled structures that exert large loads on and require large foundations to support them. They are generally very sensitive to foundation settlements as it may hinder the performance of tanks resulting in significant commercial or social impacts. Selection of their foundation is dependent on availability of suitable ground and limitations imposed by design specifications. Design of the tank foundations is generally based on theoretical methods and validation by representative field tests. This paper reviews settlement criteria for storage tanks as per national and international standards, case studies of large to medium diameter tanks supported on deep foundation i.e., bored cast-in-situ piles and shallow foundations on improved ground and their performance during load tests & hydro-tests is discussed. Paper concludes that storage tanks can also be supported on shallow foundations resting on improved ground reducing the settlement, time and cost significantly depending on the sub-soil.

Nov 1, 2022

By Sunil S. Basarkar, Vinothkumar S

Ground Improvement Techniques serves to improve various engineering properties for supporting various foundations. These may be undertaken either by conventional or advanced methods. The Controlled Modulus Column (CMC), also known as Rigid Inclusion is a soil improvement technique to reduce the total and differential settlement by using semi-rigid soil reinforcement columns. The CMC technique can be executed by displacement or non-displacement methods. It does not aim to bypass the compressive layer or to install a pile that will directly support the entire load from the structure. Principle of the technique is to introduce a load transfer platform between the head of the column and structure and transform a uniform load into soil. Initially, the structural load transmitted into the soil generate the settlement greater than CMC piles. When the settlement between the soil and column became equal at neutral point, maximum structural load shall be balanced by the positive friction and tip resistance to stabilize the foundation without exceeding the allowable settlement limit. This paper describes the behaviour of soil reinforcement with CMC column and their installation process with reference to a project at the Dry Bulk Terminal Port, San Pedro- Abidjan (Western Africa). Methodology of CMC, requirements of Ground Improvement, arrangements and outcome of this method are presented in this paper.

Sep 1, 2022