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By Stephen Slomski, Benjamin White, Bradley Klausing

Integrity assessment of drilled shafts can be determined by considering information from many points in the construction process. Observation of the drilling and shaft installation can provide additional confidence in the foundation element. Material testing is commonplace and provides another quality assurance. This information should be considered and is critical to the final evaluation of shaft integrity. Integrity testing is an in-situ method that evaluates the shaft as constructed. Several testing methods, each with its own strengths and limitations, are available to evaluate the integrity of a shaft. This article discusses three types of tests, thermal integrity profiling, low-strain integrity testing and high-strain dynamic testing, and their results from drilled shafts installed to support two county road projects.

Jan 1, 2025

By Andrew Lees

Where in-situ ground is too weak to support piling rigs and other mobile plants, a temporary platform of stronger granular material may be constructed to distribute plant loads safely to the underlying ground. A critical step in the construction of a safe working platform is its design. Essentially, the optimal thickness of the platform material needs to be determined such that it is large enough to distribute piling rig track pressures safely to the ground without bearing failure, but not so large that it becomes unnecessarily expensive and time-consuming to construct. Platform failure can take several geotechnical forms including punching shear failure through the platform into the underlying soil and a rotational slip failure. Any, or a combination, of these could lead to platform failure and a catastrophic toppling of a piling rig. Safe design of these temporary struc- tures requires a calculation method that can cover these failure modes in a reliable manner. The T-value calculation method considers multiple failure modes since it is derived from validated finite element analysis (FEA) that has no predetermined failure modes. Since its introduction in 2019, it has been applied to the design of hundreds of working platforms around the world. On its fifth birthday, the method's author provides a quick overview and advice on its use.

Jan 1, 2025

By Bengt Fellenius

I remember the 1983 conference and this "DFI News" note with its summary of my lecture - and how I cringed on seeing the heading of the note, claiming that I had "released the wave equation." The WEAP (wave equation analysis of pile driving) had been "released" about a decade earlier by the founders of GRL Engineers and Pile Dynamics, George Goble and Frank Rausche, marking the beginning of their great contributions to the geotechnical engineering practice "the quantum leap." I appreciate the opportunity, now 40 years later, to correct the heading implication. Several typos in the note, then irritating, are now more amusing, such as, "dull complex" instead of "full" and "restriction" instead of "restrike." My lecture tried to introduce some of the then recently developed dynamic monitoring and analysis state of the practice: the WEAP and PDA/CAPWAP (Pile Driving Analyzer/CAse Pile Wave Analysis Program). The lecture and the notes should be read in the light of how they were operated in early years. The mainframe computer and input was by means of punch cards. The field testing using the PDA was by lugging the analyzer, a bulky tape recorder, an oscilloscope, and power-cable and gage-chord bundles to the site. If travel was by air, the analyzer sat on the seat next to the engineer. For assessing the pile in the field, the measurements were printed out on a paper roll. In the mid-1980s, a screen was added to the analyzer, it became digital, and data were stored and accessible electroni- cally also in the field. No more tape recorder and oscilloscope. At about the same time, the PC arrived and the WEAP became available for running on the office machine. Process was slow; while the PC ran a WEAP, it was time for a cigarette and a cup of coffee. To think through the input to the analysis, there- fore, became an important time-saving effort. Soon thereafter, the CAPWAP also became available for use on a PC. The first International Stress Wave Conference in Stockholm in 1980 (it continued every fourth year, thereafter) started the international acceptance of monitoring. At the third conference, in Ottawa in 1988, the number of indi- viduals outside of GRL performing CAPWAP analysis amounted to 17, with 14 from outside the U.S. Today, the high-strain dynamic monitoring is routine wherever piles are driven, and its use has been extended to testing non-driven piles. The wave equation and high-strain dynamic method, then and now, is for assessing pile-soil response in terms of pile capacity and hammer perfor- mance. Over the years since, it has been extended to low-strain integrity testing and current advancement of tech- nology has been incorporated. For example, the connection between pile gages is now wireless and the analyzer is a tablet. The pile monitoring data can be sent to the "cloud" and enable remote testing. The process is so fast that an automatic signal matching can be made in real time on every blow. At some sites, every pile is tested, thus, the method is used for continuous quality control of the hammer-pile-soil system.

Jan 1, 2025

By Peter Faust, Mike Muchard

The I-205 improvements in Oregon include the seismic retrofit and widening of the Abernethy Bridge to withstand major earthquakes. When completed it will be the first earthquake-ready bridge that crosses the Willamette River in the Portland metropolitan area; establishing it as the regional north-south lifeline route after a disaster. To meet seismic performance goals, critical bridge piers were retrofitted with very large and deep nonredundant (single) drilled shafts with "outrigger" bents. New drilled shafts and columns were constructed on both sides of these piers supporting a new post tensioned "super beam." While the drHled shaft scope of the project is now finished, construction is still underway for the project, which is due for completion in 2025. Once the load is transferred to the new outrigger bents, the existing columns will be removed. Drilled shaft diameters for the river crossing ranged from 8.2-12.25 ft (2.5-3.7 m), with the largest shafts extending over 240 ft (73 m) in length. This size drilled shaft surpasses the typical dimensions used for transportation structures. Given the enormity of these shafts, combined with the complex geology and site constraints, the Oregon Department of Transportation required a prequalification process to select the foundation contractor, Malcolm Drilling.

Jan 1, 2025

By Johann Kraxenberger, Matthew Gregory, Bauer Maschinen, Deon Lauw, Franz-Wener Gerressen, Robert West

High Speed Two (HS2) is a major high-speed railway project in the U.K. connecting London to the West Midlands. The 21 km (13 mi) of twin-bore tunnels in London include numerous geotechnical structures and extensive foundation works, such as embedded retaining walls and cut-and-cover box structures. There are approximately 1,800 rotary bored contiguous retaining wall and bearing piles in the Euston Station Approaches alone. Piles are constructed mainly in the London clay formation and Lambeth group. Some, however, were advanced to the Thanet sand formation at approximately 49 m (160 ft) from ground level. The diameters of these piles range from 750-1,800 mm (29-71 in) and most are constructed using a polymer support fluid to stabilise the soils during boring. Pile cut off level was located within the cohesive soils of the London clay with each pile reinforced with a full-length cage. Striving to achieve low carbon solutions for typical opera­tions on the site, several innovations were conceived.

Nov 1, 2024

By Jesse Rauser, Gavin Gautreau, Xin Peng

The field of deep foundation engineering is undergoing significant changes. Long reliant on established methods and expert judgment, the industry is now integrating data-driven techniques that are transforming how infrastructure is designed and built. This shift is not about abandoning proven practices, but about enhancing them with advanced analytics and data tools to improve accuracy, efficiency and adaptability in construction projects. Picture a worksite where decisions are made not just from experience, but also informed by data from previous projects and real-time analysis. This isn't a vision of the distant future but the reality of today's deep foundation projects. Data-driven techniques are being combined with engineering expertise, creating smarter and more reliable solutions that can handle the increasing demands for sustainable, resilient infrastructure. While traditional methods based on empirical data and experienced judg­ment have served the industry well, they are sometimes limited in ad­dressing modern challenges, such as evolving environmental regulations While traditional methods based on empirical data and experienced judg­ment have served the industry well, they are sometimes limited in ad­dressing modern challenges, such as evolving environmental regulations foundational engineering processes. These new techniques allow profes­sionals to analyze larger volumes of data to optimize designs, enhance decision-making and achieve better project outcomes.

Nov 1, 2024

By Katie Kontos

The changing landscape of the deep foundations industry is being propelled by many things-most prominently, digitalization, automation and increased emphasis for sustainability. But this is only the tip of the iceberg when it comes to innovation. With all this change ahead, DFI turns to several of its forward thinkers to ask what the future looks like. What challenges will arise? How can the industry prepare to head into the new world of artificial intelligence (Al)? And what can be done NOW to support and empower the future generation of geoprofessionals?

Nov 1, 2024

By Aaron Gallant

Civil engineering and construction companies are increasingly aware of the environmental impact and associated greenhouse gas (GHG) emissions linked to their daily operations and design decisions. Many have already taken significant steps to track and report emissions to better understand their impact on the global carbon footprint. Most generally align accounting practices with the Greenhouse Gas Protocol {GHG Protocol), which has become the most widely adopted international framework to measure and report GHG emissions. The GHG Protocol was developed by the World Resources Institute and the World Business Council for Sustainable Development and categorizes emissions into three scopes. Scope 1 constitutes direct emissions caused by operating equipment and resources it controls and owns (e.g., fossil fuels to run machinery, vehicles, etc.). Scope 2 incorporates indirect emissions linked to purchased electricity, heat, or energy owned or operated by a third party, but influenced by the individual entity's usage. Scope 3 encompasses all other indirect emis­sions associated with entity operations. In other words, Scope 3 attempts to put a spotlight on the indirect emissions within an entity's entire value chain that allow the entity to operate and provide a service.

Nov 1, 2024

By Derrick Dasenbrock

Geotechnical engineers are usually well-acquainted with contractual and noncontractual documents used to convey geotechnical information in a construction project - typically sub-surface exploration logs, engineering and geology reports, project plans, and contract specifi­cations. Both owners and contractors rely on com­plete , appropriate and accurate information in contract and informational documents to achieve the successful delivery of projects, com- municating requirements to meet budget, schedule, safety, performance and other goals. Traditionally, contract documents have been created and delivered through paper plans and reports or electronic paper equivalents such as PDFs. Geotechnical information is often included in these documents in an unstructured format. Geotechnical requirements may be shown on the plans, or included in the project special provisions, standard provisions or gov­erning geotechnical agency manuals. Simplified geotechnical logs may appear on plan sheets with more complete logs available elsewhere. Additional documents may reference field, lab, geologic, materials or other additional reports, which are often neither readily available to on-site workers nor contractual in their nature. Nearly always, geotechnical infor­mation is provided in a static format, rather than as structured digital data, decreasing its utility to contractors for bidding, design analysis and con­structabilityevaluations.

Nov 1, 2024

By Emad Farouz, Ali Albatal, Ehab Shatnawi

Drilled shafts are deep foundations that can carry heavy loads by transferring them to deeper and stronger soil or rock layers.  The paper focuses on the drilled shafts installed in the Potomac Clayey Formation in the northern part of Virginia. The paper shares the lessons learned from using steel casing during drilling. Two load tests were done on drilled shafts with 75-centimeter diameter and 21-meter length. The first load test failed to reach the loading capacity, while the second load test succeeded after changing the installation method. The paper explains the subsurface conditions and the design methods used to estimate the axial capacity of the drilled shafts. The paper gives details about the installation methods and the reasons for not reaching the axial capacity with a standard installation method. The paper offers useful insights into how the construction method affects the axial capacity of drilled shafts.

Oct 7, 2024

By Mriganabh Choudhury, Sanjoy Bhowmik, Sampat Raj, Vijay Panwar

Tanks play a vital role in Petroleum refineries and Petrochemical complexes by storing Petroleum substances at various stages. The performance of the foundation system of tanks significantly influences their overall performance, which is evaluated during hydro-testing and operational phases. This study focuses on assessing the performance of a large-diameter floating roof tank measuring 92 m in diameter and 20 m in height, which exhibited excessive settlements during hydro-testing due to the presence of organic soil patches. The maximum total settlement observed was 238 mm, surpassing the permissible limit of 150 mm. Additionally, differential settlements at specific locations exceeded the acceptable limit of 1 in 500. A comprehensive performance analysis of the tank's foundation system was conducted, leading to the tank's approval for utilization at 100% capacity. Furthermore, remedial measures were proposed to address the uneven levels at the tank periphery and prevent settlements in the future. This paper highlights the significance of location-specific soil investigation data, critical parameters for tank foundation system selection, detailed performance analysis of tank foundations, and suggested remedial measures for distressed foundations. By addressing these crucial factors, the study enhances the understanding of tank foundation systems, ultimately improving the overall performance and reliability of tanks in Petroleum refineries and Petrochemical complexes. Keywords: Storage tanks, Performance analysis, Hydro-test, settlement, Ground improvement

Oct 7, 2024

By Mark Dowling, Robert Holdway, Bill Baillie

Extending the utility of materials through reuse, repurpose and recycling to minimize waste, pollution, water, and the consumption of finite resources, reduce environmental impacts and cut GHG emissions (CO2) are key tenants of the Circular Economy. John Lawrie Tubulars USA conducted a Life Cycle Assessment to calculate the environmental impacts of the repurposing of John Lawrie Tubulars steel pipe products sourced from pipe mill secondary and oil field surplus stockpiles to compare repurposed steel tubulars to those made from prime (new mill) steel throughout their lifecycle. The analysis includes multiple environmental characterization indicators associated with the material processing, on-site operations, supply chain, distribution, and installation of the pipe for foundations. The benefits of repurposed tubulars are consistently beneficial across all environmental indicators when compared to prime steel tubulars. The life cycle analysis results show that for every tonne of steel tubular repurposed there is a 71% - 80% saving of carbon emissions over the use of a prime steel equivalent from cradle to installation. The methodology used in this study will be described, demonstrating the rigor and 3rd party verification process involved in calculating the CO2 emission savings, one of the first of its kind for secondary steel suppliers in North America. With growing pressure on the construction industry to be more resource efficient, and to lower embodied carbon, material reuse strategies are critical to meet targets. This data can be used to demonstrate, and quantify, the environmental impacts and benefits of repurposed tubulars and supports the efficacy of environmental claims and contribution to a circular economy.

Oct 7, 2024

By Jim Glider, Peter Faust, David Joyner, Michael Muchard

The existing, century-old Portal Bridge over the Hackensack River in New Jersey is a two-track moveable swing span bridge that is nearing the end of its functional life. A new fixed bridge with spans of approximately 400 feet will replace the existing bridge. The new Portal North Bridge will continue service to both Amtrak and NJ Transit rail passengers along the Northeast Corridor to an average of 200,000 passengers per day. Each of the four main span piers will be supported by eight, 8-foot diameter drilled shafts. Malcolm Drilling installed all shafts with permanent steel casing through the Soft Clay and Glacial Till layers with a short embedment into competent bedrock using the Oscillator method. Rock sockets below the casing were drilled with conventional drilling tools. Quality assurance included inspection of the shaft base using a MiniSID shaft inspection, the rock socket side walls using a Down-The-Hole Camera and the verticality using Sonic Caliper. In addition, specifications called for integrity testing using Thermal Integrity Profiling (TIP) and Crosshole Sonic Logging (CSL) on each shaft. Tomography analyses of CSL test data and destructive testing by means of concrete coring had also to be employed on the majority of shafts. This paper will highlight the surprises experienced by the project team when the concrete core specimens were evaluated in relation to the non-destructive testing data.

Oct 7, 2024

By Joe Heinisch, Trevor Quayle, Brian Huber

Helical piles have often been characterized as handy little tools in the toolbox of solutions for structural support of foundations. They have provided options to construct foundations and anchorage in very challenging locations where more common methods were impractical. The stigma of being efficient for lightly loaded foundations has limited their use as highly loaded deep foundations. This paper will dispel the notion that helical piles are not a deep foundation option for large structures by presenting the case study of a 32-storey building in London, Ontario supported on helical piles. The building was constructed in a downtown location where all the problems associated with deep foundations were present – high water table, vibrations, compressible soil layers, limited access, logistics of soil removal, seismic considerations. These issues all had costs associated with them that helical piles and their installation process would limit or eliminate. This paper will present the detailed solution that helical piles offered the constructor of the new building. The solution included pre-design load testing and analysis of the results. The advantages of using helical piles in this case will also be presented from technical and constructability viewpoints to demonstrate why they should be considered for large structures.

Oct 7, 2024

By Max Ho, Hiu Lee

The Port Lands in Downtown Toronto is a vast waterfront area that has been long remained undeveloped. This is due to the dual challenges of soil contamination resulting from decades of industrial activities and high flooding potential from the nearby Don River. The Port Lands Flood Protection and Enabling Infrastructure Project (PLFP) seeks to unlock the development potential of this strategic downtown land. This initiative also simultaneously mitigating flood risks for the Port Lands and surrounding areas. The project involves the creation of a new river channel through the existing Port Lands to redirect floodwaters into the inner harbor and Lake Ontario. This new river channel excavation is protected by three dam liked plug walls which isolate the lake water from entering the excavation. Given the industrial contamination in the soil, the installation of a permanent cut-off wall along the new river alignment is also imperative to isolate contaminants from migrating into the future river channel. The west plug wall is positioned at the westernmost point of the river channel excavation and directly adjacent to Lake Ontario. The innovative use of a diaphragm wall technique to construct the west plug wall allow the wall to serve as a dock wall, dam, excavation support, cut-off wall, and load-bearing element throughout the different stages of the river excavation. This paper provides a comprehensive overview of the design and installation of the west plug wall. It provides valuable insights into the practical application of diaphragm walls and how it helps deliver this complex urban flood protection and infrastructure projects.

Oct 7, 2024

By Marcel Martineau, Vincent Landry, Simon Didone Arseneau, Ali Fallah Yeznabad, Damien Lamblot, Mathieu Cattone, Habib Akande, Marion Bouet

Vaudreuil-Soulanges Hospital Center in Greater Montreal area is a substantially large construction project with challenging schedule and geological conditions. The foundation consisted of 519 piles with an average overburden of 15 m and 4.5 rock sockets that were constructed in a tight schedule of 9 months. Special Geotechnical considerations were required and adopted for design and construction of this large-scale foundation. In this Design and Build contract, the strong cooperation between the designer and the contractor resulted in a substantial optimization of the quantities through in-situ full-scale vertical static and lateral cyclic pile-load tests, seismic simulations in design of the piles, and orienting the design to fit the planned drilling method. To maintain a challenging schedule in a cost-effective manner, seven drilling rigs fitted with temporary casings were used, operating in two shifts up to seven days a week. For drilling of the piles, cluster drilling was used by contractor due to uncommon abrasiveness and high strength (> 200 MPa) of the encountered sandstone bedrock. To further assist the construction of the piles, a new concrete mix was developed specifically for this project for the purpose of tremie pours. The concrete mix design is based on optimizing its rheology, maintaining its workability up to 6 hours and its durability more than 75 years design life in a particularly aggressive environment in chloride, sulfate, and others aggressive ions. An effective quality control and assurance program made it possible to find optimal solutions during construction.

Oct 7, 2024

By Blaise Fettig

Santa Cruz Mountains, Ben Lomond, CA Vortex Project Sponsor- Blaise Fettig Vortex PM- Peter Dworetzky Obayashi Corp (Prime Contractor) PM- Kenji Yamauchi ABSTRACT: The City of Santa Cruz Water Department in California replaced the existing Newell Creek Dam inlet/outlet works. The existing inlet/outlet works included a deteriorated 36-inch diameter pipeline under the dam and other components that did not meet current California DSOD dam safety reservoir drawdown requirements. To maintain the reservoir, the City’s engineer designed a new inlet/outlet works that could be constructed under full reservoir conditions, in water up to 115 feet deep. The underwater work began with the dredging of an “amphitheater” on the native 2:1 rock slope. After dredging, three large, critically located benches were excavated into the rock slope with a heavy digging bucket and specialty designed underwater tools. A marine rail was constructed, on which three large concrete donuts were precast and lowered into the water before picking with a crane. These donuts were then installed and grouted in place on the excavated benches. Six foot diameter shafts were drilled through the hole at each inlet foundation donut to the tunnel intersect elevation, and steel casings were installed and grouted into each shaft. Divers installed the three intake structures at design elevations. These 30” intake structures were 30-inch standpipes with 30” diameter hydraulic valves and 48” diameter by 56” tall drum screens. The piping was connected to a 20” diameter air vent line which is designed to prevent vacuum conditions and plumbing to provide a minimum downstream flow. Once the shafts and intakes were in place, a new tunnel was advanced by the general contractor from the downstream right abutment to intercept the shafts. 30” CISS piles were installed to support the 20” vent line from the intake locations to the dam crest. These piles were drilled from barges. Divers then installed Vortex designed articulating pipe supports on the piles, and finally the vent pipe to shore.

Oct 7, 2024

By Seth Hamblin, Bill Oder, Les Chernauskas

Thermal Integrity Profiling is a non-destructive test method used on cast-in-place concrete deep foundation elements such as drilled shafts.  The method has progress steadily over the last 15 years with improvements to the equipment, data acquisition and analysis of the data. Current analysis of TIP data incorporates temperature vs depth and temperature vs. time. The current acceptance criteria for TIP includes using reductions in effective shaft radius and concrete cover (Piscsalko, et al. 2016).   However, these criteria are heavily based on knowledge of concrete volume and can be significantly affected by the lack of good concrete volume data.  An additional criterion using temperature is proposed for potential use in the industry, which can supplement the existing effective radius/cover criteria and will be less dependent on volume knowledge. However, the relationship between temperature reductions and defect size and position are not well known for various reasons.  The major reasons for this include; not a lot of studies/data available, variations in mix designs, variations in shaft sizes, and variation in defect types. Research was recently performed by the Authors on three drilled shafts with manufactured defects under grants from DFI and ADSC.  The study included running theoretical simulations to predict the sensitivity of temperature reductions to the defect size and location. Data was collected and the temperature with depth was compiled for various defects. The results show a promising relationship between temperature reduction and defect cross sectional area.  When considering local temperatures and average temperature changes, the criteria can consider location and size.   When including data from other recent research studies for similar size shafts and defects, we found the relationship to be consistent with our data.  The findings of this research provided a better understanding of the relationship between temperature reductions and defect size and location and provide the basis of the proposed temperature criteria.  

Oct 7, 2024

By Tony Sangiuliano, Jason Weck, Ryan Regier, Alper Turan

Cast-in-place concrete piles socketed in rock are a commonly used foundation solution in the province of Ontario. Although cast-in-place concrete piles are common, limited pile load testing has been undertaken on these foundations to confirm shaft friction (side shear) and end bearing parameters. Particularly, the large diameter piles bearing on rock makes conventional pile loads tests impractical and costly due to large capacities that need to be mobilized during testing. Performance of piles loads test come with the advantage of confirming the assumed geotechnical design parameters and permitting the use the larger strength reduction factor as per LRFD design. This paper presents the preparation, execution, and result interpretation of a pile load test carried out on two Cast-in-place concrete piles with diameters of 1.5m and 1.8m for Garden City Skyway Project in the City of St Catherines Ontario, Canada. The 1.5m and 1.8m diameter test piles were socketed 4m and 6m into shale bedrock. Osterberg cells were used in both load tests to provide end bearing and shaft friction parameters for the shale bedrock as well as overlying layers of till and soft clay. The results of the load test provided valuable insight into the load settlement performance exhibited by these piles. The results are also compared with the analytical estimates of the pile capacities presented in geotechnical report as well as the results of a number of other analytical socket design approaches.

Oct 7, 2024

By Rajni Saggu

This study presents the cyclic load-displacement response of thermal piles in a pile group consisting of thermal and mechanical piles. To investigate the effect of different (i) layouts of thermal piles and mechanical piles, (ii) pile spacing, and (iii) soil type on the pile displacements and axial stresses, numerical analyses were performed over 50 cycles of thermal loading and unloading of the thermal piles. The analysis outcomes show that the thermal changes in the load-displacement characteristics of the piles become complex during cyclic thermal loading and unloading of the thermal piles. The mechanical piles also exhibit uplift after thermal loading of the thermal piles, and significant differential displacements occur at the pile cap, head and base for all the piles. Higher pile spacing imposes a positive effect in terms of lower thermo-mechanical stresses in the piles compared to the case of closely spaced piles. Axial stresses in each pile are notably non-uniform after the thermal loading cycles applied on the thermal piles. Cyclic alterations in the load-displacement of thermal piles also impose alterations in load-displacement of the mechanical piles. Further, the layout of thermal piles, pile spacing, and soil type control the long-term cyclic thermo-mechanical response of the pile group.

Oct 7, 2024