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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 T. Szendrei, S. Tose

The generally accepted view in rock blasting is that the sources of energy for the fracture and movement of rock reside in the shock wave and gas action resulting from the explosion, and yet the mechanisms by which these sources interact with the rock have remained unclarified. It has also been noted that up to 50% of the work capacity of an explosive released in a blast cannot be accounted for by field measurements of energy partitioning. In this study, we describe a physical model that details the response of rock to both shock wave and gas action. An analytical model based on momentum conservation is derived to describe the dynamics of shock-driven expansion of the blasthole. Radial expansion of the hole is the key parameter that permits the derivation of the following characteristics of rock response to shock loads: hole expansion time; volume of displaced rock; energy consumed per unit volume; expansion energy efficiency; stress wave pulse length; gas pressure in enlarged hole. Soon after the completion of hole expansion, the shock wave degenerates to an elastic stress wave that runs through the burden. Blasthole expansions of between 50% and 300% of diameter are completed in under 1 ms and, depending on rock properties, consume 32% to 42% of the detonation energy or about 55% of the available mechanical (Gurney) energy. Gas pressure in the enlarged holes in five rock types is between 35 MPa and 650 MPa, and drives the mass movement of burden rock.

Oct 9, 2024

By J. Hadjigeorgiou, G. Knox

Since their introduction in 2010, paddled energy-absorbing rockbolts have been widely used in seismically active hard rock mines. This paper provides new data and reviews previous work to quantify the performance of paddled energy-absorbing rockbolts under controlled laboratory conditions. Of significance is the realization that the typical split location in impact tests, at the centre between two paddle anchor points can at best provide an upper limit value. This inherent variability in performance under different testing configurations should be acknowledged and taken into consideration in the design of ground support in seismic conditions. This paper discusses the reduction in capacity of paddled rockbolts as a function of loading angle from a maximum value during axial tests (0° loading angle) to the lowest value during pure shear (loading angle of 90°). A significant reduction in displacement capacity is observed as the loading angle changes between axial (0°) and 40°. Beyond a 40° loading angle up to shear (90°) loading the reduction in displacement capacity is less significant. Due to the variances in the capacity observed through the variance of the testing configuration: loading mechanism, direction of loading, location / presence of a discontinuity, it must be recognized that results from laboratory-based testing are not independent of the testing configuration. This should be acknowledged when extrapolating anticipated performance in the field.

Oct 9, 2024

By E. Matinde

Poor phase separation and fine dissemination of the desired components within congruous slag phases are key challenges limiting the recoverability of values from slags by conventional beneficiation methods. Slag microstructure conditioning is a pragmatic approach to increasing themvalue-in-use of discard slags, especially when integrated with the broader smelter infrastructure. Although not yet tested on oxide slag systems, this paper explores the potential application of magnetohydrodynamic principles to the crystallization behaviour of bulk slags. Integrating the slag microstructure conditioning infrastructure to the existing smelter infrastructure is key to unlocking the economic value of slags because it is most economic to condition the properties of molten slag directly after tapping. A new business model that integrates smelting units to transversalmeconomic activities, such as cement production and suppliers of construction aggregates, canmsignificantly increase the circularity of metallurgical slags.

Oct 9, 2024

By F. D. Agrensa, J. Hadjigeorgiou, E. Storimans, S. J. Thorpe

Reinforcement and surface support are part of an integrated system that transfers and shares loaduntil the excavation surface is stabilized or until the ground support system fails. Steel mesh is the most popular primary surface support element in underground hard rock mines in Canada. Mesh straps are a secondary surface support that provide additional containment as they distribute the load between and across the reinforcement elements. This investigation addresses the role of steel properties, and in particular steel chemistry, in the long-term performance of mesh and mesh straps when exposed to an aggressive corrosive environment. It reports on comparative accelerated corrosion studies to compare the resistance to corrosion of different surface support elements. This has significant implications on the choice of surface support and the anticipated rehabilitation requirements.

Oct 9, 2024

By E. Kuipa, J. N. Lekunze

The selection of an underground mining method stems from a multivariate analysis that considers geomechanical, geological, economic, and operational parameters. Even after identifying the most compatible method, there is no assurance that the mining company will achieve the best performance. The geological complexity of some deposits requires adaptations of methods described in the literature to obtain more selectivity and reduce mining waste. There are some studies on geometry of underground structures, but a methodology that describes an adaptation of a room-and-pillar mining method for ore bodies with down-dip varying from 20° to 25° is novel. The present work aimed to reduce dilution by adapting the traditional room-and-pillar mining method (TRP) to inclined ore boLittle attention has been paid to the rehabilitation of derelict and ownerless mines in South Africa after their lifespan. This paper aims to explore management gaps in legislation that have resulted in the non-rehabilitation of derelict and ownerless mines in South Africa. There is growing evidence that supports the distressing effects of mining on people living around these mines in the North West Province. This paper was motivated by the current socio-economic status quo of old mining towns, the influx of illegal miners (Zama Zamas), severe environmental damages, and the violence associated with derelict mines. Underpinning this research was an ecosystem approach and integrated resources management principles, which formed the foundation for the decision-making process.The researcher used a mixed-method approach and employed convergent techniques. A semi-structured instrument was used to collect data from 200 respondents. The results indicated that there is a dire need for community-based consultative processes, and an absence of clear guidelines for derelict and ownerless mines to pressure mine management to adhere to rehabilitation standards. Moreover, the mining charter is ambiguous regarding policy implementation, budgetary allocation, and duration of the rehabilitation of these mines. The paper concluded that management challenges associated with derelict mines can be reduced if all stakeholders follow the guidelines as outlined in the environmental legislative framework (NEMA) of South Africa while being open to innovations in line with international best practices. It also contributes towards the development of guidelines for the management and implementation of legislation related to derelict and ownerless mines in South Africa from a philosophical, theoretical, and policy perspectivedies. This new method is entitled short-hole room-and-pillar (SHRP). The equations that measure the dilution are defined according to the geometry of stopes and openings. The results comprise comparative analyses of the operational and planned dilutions to measure the performance of the SHRP method. The average operating dilution of the SHRP method was more than five times lower than the planned dilution according to the TRP method. Low operational dilution indicates high selectivity of the method and its potential to reduce underground mining tailings.

Oct 9, 2024

By B. Besa, S. Nalukui

Globally, the demand for mineral products is ever increasing. Extraction of these mineral resources results in the continuous production of a huge volume of waste material, including tailing dumps. The mass of tailings usually exceeds the actual resource and often contains hazardous contaminants. This study investigated the effects of tailings disposal on soil, water, and air quality in the Nampundwe area. Water, soil, and dust samples were collected from different locations in the surrounding communities. The constituents analysed in the samples included copper, cobalt, iron, sulfate, and silica. According to the results obtained, some seepages occurred from the tailings impoundment to the shallow aquifer in the area. However, the general water quality meets the Zambia Environmental Management Agency (ZEMA) statutory limits. Recorded concentrations of sulfate (1500 mg/l), copper (1.5 mg/l), cobalt (1.0 mg/l), iron (2.0 mg/l), and silica were between 0.003 mg/l and 705 mg/l, which is far below ZEMA’s statutory limit. Silica concentration was also evident in the air. The highest concentration recorded was 260 ppcc (particle per cubic centimeter) recorded in July 2019 from the northern direction of the tailings dam. The concentration was below the statutory limit of 350 ppcc. The topsoil from the northern part of the tailings recorded a silica dust concentration of 39.9 ppcc. Iron was evident in the underground soil with a concentration of 8.01 ppcc, cobalt 0.005 ppcc, copper 0.051 ppcc, while sulfate was recorded as 0.41 ppcc.

Oct 9, 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