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By A. Fisher

The use of thermal integrity testing to verify the quality of deep foundations has increased significantly in the UK and other world markets over the last 5 years. The introduction of distributed fibre optic sensing to this field has broadened the range of applications in which it can be deployed and the types of foundations which can be tested. This paper presents how fibre optic sensing technology can be successfully deployed in the construction environment the range of foundation techniques to which it can be applied. Alongside developments in the practical aspects of thermal testing, progress has been made in establishing assessment criteria which can be used to evaluate the results. This paper presents recent examples of comparative studies on foundations which include both thermal integrity testing, cross hole sonic logging and intrusive coring. The use of distributed strain measurement during pile load testing presents an alternative means to verify the assessment criteria used for integrity testing. This new approach can achieve comparable results to foundation exhumation or intrusive investigation and at a fraction of the cost. This paper presents the findings of several such studies, highlighting the benefits and opportunities for future improvement of the method.

Oct 1, 2022

By Boo Hyun Nam, Berk Turkel, Luis G. Arboleda-Monsalve, Jorge E. Orozco-Herrera

Construction of buildings, roads, and traffic activities generate vibrations to urban infrastructure. The vibrations produced by construction activities have an impact on the soil through which they are transmitted. These effects become much more significant in granular soils. The soil conditions in Florida consist mainly of sandy soil deposits and this makes driven piles a commonly used method. In the design of deep foundation installations, it is significant to consider the potential construction issues related to the driving process. This process generates vibrations in the surrounding soils and thus, its effects on nearby soils and structures must be considered. This paper presents a web-based survey conducted among geotechnical engineers in Florida to better understand the common practice and experience regarding the effects of pile driving on surrounding soils and structures. The perception of different practitioners in the state of Florida on ground deformations and damages to adjacent structures induced by deep foundation installations are investigated. The engineers who have experienced ground vibrations and deformations were asked to define the susceptible soil conditions and main triggering factors of large ground deformations induced by pile driving. Sandy soils with loose to medium relative densities were found to be the most susceptible soil condition to generate ground deformations. Conclusions are drawn regarding the importance of considering ground vibration monitoring during the design phase of deep foundations.

Oct 1, 2022

By Abolfazl Eslami, Fatemeh Rostami, Sara Heidarie Golafzani, Mohammad Arabameri

Collapsible loess is classified as problematic soil found in most continents. The loess immediately collapses under stresses induced by axial compressive loading or the soil weight when exposed to moisture. In Iran, vast areas of the Golestan province are covered with aeolian loess deposits. This paper investigates whether the simultaneous effect of inundation and pre-loading in helical pile installation are operative and effective in improvement of Golestan loess. The effect of installation conditions on loess collapsibility is studied via two main approaches, i.e., field investigations and physical modelling. The experimental studies include installation of eight single helix piles in the Amirkabir University of Technology Frustum Confining Vessel, i.e., FCV-AUT. Also, four single helix piles with embedment depth of 3 m and diameter of 250 mm were installed in Golestan province and full-scale pile static loading tests were performed. The results indicated that the simultaneous application of crowd loading and water pressure during installation of helical piles results in better soil shear strength parameters. Moreover, high crowd stresses or low crowd stresses accompanied by water pressure during pile installation brings about similar load-displacement behavior of model piles installed in FCV-AUT and full-scale helical piles.

Oct 1, 2022

By Karen Talbot, Noah Maier, Rob Jameson, Giuseppe Gaspari

A storage and drainage tunnel advancing below I-75 in Detroit, Michigan experienced sudden subsidence. The Tunnel Boring Machine (TBM) was damaged to the extent that its shield, cutting head and extensive interior components needed to be extracted and replaced along with several completed tunnel segments. The tunnel was 16 feet (4.9m) in diameter with crown over 79 feet (24m) deep at the time. The tunneling contractor immediately engaged their designers and specialty subcontractors to develop a scheme to access the machine and repair the tunnel. They required a shaft 99 feet (30m) deep, with unobstructed plan dimension of 50 feet (15m) to accommodate the large components that needed to be removed and replaced. This precluded the application of an internally braced excavation and instead earth support solutions focused on use of a compression ring. Since the completed tunnel section behind the TBM obstructed closure of the compression ring below its invert, this paper describes the innovative access shaft solution employed. A conventional compression ring was constructed using 5 feet (1.5m) diameter drilled shafts down to the tunnel crown. In front of, and to the sides of the tunnel heading, the secant shafts were extended to over 150 feet (46m) depth, creating a horseshoe of support extending 50 feet (15m) below the planned excavation invert. Larger diameter "King Pile" shafts were drilled immediately to either side of the tunnel, overlapped into each end of the secant "horseshoe". The king pile shafts, together with a heavily reinforced ring beam above the crown elevation, acted as a door frame to transfer hoop loads from the incomplete secant arc into reaction supports above and below the tunnel. These oversize king pile shafts were extended and socketed into rock over 70 feet (21m) below tunnel invert. Very tight installation tolerances were necessary to maintain secant shaft alignment to depths exceeding 150 feet (46m). The project operational, geotechnical, and quality data was managed and visualized using a custom GIS interface. This paper will present the design approach employed and review the construction and quality program selected to repair the tunnel.

Oct 1, 2022

By Bernardo J. Jiménez Vega, Edy L. T. Montalvan

During the last phase of the Circunvalacion Norte project in San Jose, Costa Rica, preliminary designs for an underpass structure of over 16 km (10 miles) considered drilled shafts as an earth retaining system. Since the project’s execution was delayed and close to the deadline, it was necessary to optimize this structure, with the drilled shafts being the most critical aspect. The key element in order to obtain an improved design was characterizing the job site with a specific site study for seismic demand, and the use of advanced numerical modelling, considering soil-structure interaction. The site investigation comprised the CPT, PMT, MASW geophysical tests, deep exploration drilling, and triaxial compression tests. The terrain was modeled using an advanced constitutive model with hardening plasticity calibrated from the triaxial tests. Plaxis software was used to calibrate the seismic model for the terrain and for the dynamic analysis. Two conditions were considered for the retaining structure: free-head and fixed head. A parametric study with drilled shafts of 1.0 m (3.3 ft) and 1.2 m (3.9 ft) in diameter, and center-to-center spacing of 1.3 m (4.3 ft) and 3.0 m (9.8 ft) was conducted in order to obtain an optimized structure. For each condition of the drilled shaft wall, the computed deformations were compared for two spectrum designs: site-specific spectrum and seismic code generic spectrum. Finally, a dynamic analysis was performed to check the performance of the drilled shafts with optimized spacing using a control earthquake. Based upon seismic performance curves, the analysis showed the possibility of greater spacing for the drilled shafts compared to the original design, obtaining a 32% reduction in the total length of the drilled shafts in the project.

Oct 1, 2022

By Vijaya Bhushan Rao, Ali Semercioglu, Jason Redgers

Large diameter steel water tanks with high storage capacities impart heavy loads deep into the ground, generally requiring deep foundations to adequately support them. The use of ground improvement as a sustainable and cost effective alternative is tempting but the design of the foundations for such heavily loaded, thin-shelled structures have to meet several performance requirements such as bearing capacity, limiting the specified total settlements, typically limiting the radial differential settlement to 13mm over 10m along the circumference and dishing settlement from edge to center of 1/120 as per standard API 650 Appendix B as well as the mitigation of liquefaction induced settlement risk. Any inadequacy in the soil investigation, geotechnical design, or misrepresentation of stresses of the foundations may lead to serviceability compromise or potentially catastrophic failures. Therefore, the selection of the foundation is dependent on the availability of suitable ground report and the limitations imposed by operational requirements. Two such case studies are evaluated and compared in this paper, with tank diameters ranging from 41 to 106m in the Kingdom of Saudi Arabia, (KSA) which were founded on two types of soils and supported on deep foundations i.e., stone columns and bored cast-in-situ piles.

Oct 1, 2022

By Ryan T. Smith, Anthony Sahj, Alexander T. Darnell

Every second can count when trying to board a departing flight or catch a ride-share to your final destination. Hartsfield-Jackson Atlanta International Airport is in the midst of a project that aims to cut about 13 seconds between automated people mover trains (Plane Train) that move passengers between the terminals and concourses. The project involves extending the Plane Train tunnel west from its existing terminus under the domestic terminal. Working from inside non-public areas of the terminal, Keller North America, Inc. (Keller) incorporated systems of micropile-supported steel beams and grillage to both underpin existing columns prior to tunneling and support open-cut excavation at the tie-in of the new to the existing tunnel. Dewatering aided in mining a challenging section at the start of the drive of the mixedface, sequentially excavated tunnel and an automated instrumentation system monitored the performance of the construction and its impact to the terminal. Cut and cover egress and ventilation tunnels required braced support of excavation.

Oct 1, 2022

By Michael Arnold, Jignyash Manyam, Yoav Rappaport

The USACE required construction of over 13 miles of cutoff wall at an average depth of 65 feet for the Herbert Hoover Dike (HHD). To meet project requirements, to provide quality control and make sound operational decisions, automated data capture, retention and visualization is crucial. Accurate and complete data management allows the authors to deliver critical business insights and to improve operational efficiencies. The author’s understood the necessity of capturing all their data, and efficiently processing and displaying it for multiple stake holders, for both internal and external purposes. The authors realized early in the project life cycle that data ownership and management is one of the fundamental features of the construction process. The authors developed their own software and use two in house applications; WEB-BGM online portal and, b-project which store rig production information combined with field quality control. b-project is used to create and deliver the Enterprise Database (EDB) to the USACE. Another biproduct of capturing the production data is the generation of the Geographic Information Systems (GIS) and also business analytics visual interactive display, developed through Microsoft Power BI. The paper focuses on the business process workflow and various technologies employed and lessons learned from the field operator perspective to achieve higher returns on business software operations.

Oct 1, 2022

By Allen B. Stanton, Parthiv Brahmbhatt, Michael Grimm, Stanley L. Worst

Constructing a circular shaft consisting of secant piles has its own complications which make it more difficult than typical drilled shaft construction. Add to that performing under low overhead powerlines and sitting inside of a 40-foot deep, 50-foot diameter shaft and it becomes more about logistics than the actual drilling. The complexities associated with the Romeo Arm Interceptor Segment 5 Lining project are the focus of this paper, delving into the details that made it work successfully.

Oct 1, 2022

By Marco D. Boscardin, Benjamin H. MacKinney, Kenneth R. Allard, Kenneth A. Pidgeon, Adriane G. Boscardin

This paper presents a case history for a unique application of a system of vertical micropiles with horizontal soil nail bracing and shotcrete facing for underpinning. The system was used to support and protect an existing 2-story hospital building during demolition and renovation. The goal was to limit building movements and have the building remain in use during construction of an abutting addition. Soils at the site consisted of clean, loose to dense, sand and gravel. The original underpinning design was revised after the initial excavation revealed unsuitable soil conditions for traditional underpinning pits. An alternative system consisting of vertical micropiles (hollow bars) through the footing, combined with shotcrete and soil nails was proposed, accepted by the owner, and successfully constructed. Excavation depths were up to 15 feet (4.6 m) below the existing footings. Wall movements were monitored at regular, horizontal and vertical intervals along the hospital wall, and less than 0.6 inches (15 mm) of settlement and 0.1 inches (3 mm) of horizontal displacement throughout underpinning and construction were reported. The challenges with the original proposed support of excavation design and other alternative approaches considered will also be discussed.

Oct 1, 2022

By Martin B. Hudson, Andrew K. Cho, Rolff B. Knobel, Les R. Chernauskas, Jonathan L. Ernst

ABSTRACT The Bruce Museum, located in Greenwich, Connecticut, is home to an extensive display of art and natural history exhibitions. A large addition was designed to be constructed adjacent to the museum requiring new spread footings to be installed up to 16.5 feet below the existing foundations. The soil conditions at the site consist of highly variable sand and gravel overlying weathered rock and sound bedrock. The Contract Documents called for traditional foundation underpinning. Traditional underpinning techniques, however, presented two major challenges on this Project; (1) deep underpinning pits would be required involving multiple levels and staging with tieback support and (2) the highly variable soil and bedrock composition and elevations presented uncertainty in the design and construction of the pits. In lieu of traditional underpinning, Geosciences Testing and Research, Inc. (GTR) proposed an “active” soil nail underpinning system. A major reason that the soil nail underpinning option was feasible, related to the fact that the soil nails and facing could be installed slightly in front of the existing footings rather than directly underneath the existing footings. The soil nail wall design involved one to four rows of soil nails with nail positions and wall depth able to be adjusted “on the fly” as excavation progressed depending on the field conditions encountered. To create the “active system,” the soil nails were pre-loaded to mitigate wall deformations that would be associated with a standard passive soil nail wall design. To evaluate the performance of the active soil nail wall and confirm design assumptions, an extensive automated monitoring, on-site testing and inspection program was proposed and executed by GTR to monitor deformations of the wall and the museum in real-time, evaluate and confirm bedrock and soil bond stresses and ensure that each soil nail was pre-loaded and locked off. Careful analysis, planning, and use of the observational method illustrates the importance of collaboration between design and construction personnel and applying engineering judgement throughout construction. The use of the observational method includes the potential for modifying design based on conditions observed. This paper presents a unique case study of the “active” soil nail underpinning system to support and protect sensitive structures, close collaboration between design and construction facilitated by real-time deformation monitoring, and its successful application as a safe and cost-effective alternative to traditional underpinning.

Oct 1, 2022

By Pete Howell, Patrick Granitzki, Alicia Plinio, Janitha Batagoda

The New York City Housing Authority (NYCHA) Red Hook Houses was subjected to damage during Superstorm Sandy. As a result, the NYCHA has an ongoing project known as Restoration Associated with Sandy Recovery Program to improve the resistance against future storms. The specific project included 28 residential buildings and several service buildings within the Red Hook Development. The subsurface conditions within the eastern portion of the site included existing fill material underlain by varying stratums of very loose, loose and medium dense silty sands followed by very soft to medium stiff clay or dense silty sands. The western portion of the site included existing fill material, very loose to medium dense silty sands and organic clayey silts underlain by very soft to medium stiff sandy silts. Based on the geotechnical report, a conventional driven steel pile system was specified containing two pile depths. As part of the project bidding, an alternative pile type was recommended and analyzed to provide quicker installation, reduce vibrations, reduce noise, and provide relatively large cost savings. Due to relatively high lateral loading, an innovative double steel casing drilled displacement piles was proposed as the alternative pile option. Field testing proved the piles capable of the required project capacities and the use of drilled displacement piles as the best alternative for the project and accepted by the NYCHA.

Oct 1, 2022

By Racquel Nottingham, Marc Mastrantuono

Micropiles often provide a favourable solution for many deep foundation problems especially when significant site constraints such as confined construction sites or vibration limitations have been identified. Often the durability of buried steel elements are heavily scrutinized in order to effectively determine the rates of corrosion and methods to reduce this while still maintaining the structural integrity of the engineered solution. Practices such as sacrificial corrosion loss and the introduction of plastic sheaths have become the go-to methods of corrosion protection. Since the introduction of the micropile, other solutions have been developed, namely protection with an adequate grout encapsulation. This paper will explore corrosion protection of micropiles and the guidelines provided in the published codes and norms. Since few codes define the exact way to verify the durability of these micropiled structures, the existing data is presented and the analysis of grout encapsulation as an effective corrosion protection method is evaluated.

Oct 1, 2022

By Ramin Motamed, Fahim M. Bhuiyan, Raj V. Siddharthan

Numerical lateral load analysis based on the beam on Winkler foundation (BNWF) model (i.e., the p-y method) is a simple, and widely used tool to predict lateral responses of drilled shafts from field load tests. The lack of a site-specific p-y model for cemented soil layers such as caliche is one of the major limitations of simulating lateral load tests conducted in Las Vegas Valley. In this study, some of the existing p-y models for rock materials, such as Florida Limestone and Vuggy Limestone have been evaluated to simulate the lateral resistance of caliche. This has been done in the context of four lateral load tests in caliche-dominant sites from the recently constructed Raiders Stadium project in Las Vegas (NV). The uncertainty in characterizing the material properties of caliche has been addressed. The p-y analyses were performed using NVShaft, a MATLAB-based, comprehensive load analysis program. The applicability of the considered p-y models for caliche material was evaluated by quantifying the normalized error margins between measured and predicted lateral responses from the simulations of the mentioned load tests. Correlations between such errors and the depth and thickness of caliche in soil layers affecting numerical predictions were established, for both up to and beyond design load levels.

Oct 1, 2022

By Gerald Verbeek, Erick Baziw

Downhole Seismic Testing (DST) is an extensively utilized geotechnical tool for site characterization. DST provides low strain (<10-5) in-situ interval shear and compression wave velocity estimates. These velocities are determined by obtaining relative arrival times of source waves as they travel through the stratigraphy and are recorded by one or more vertically offset seismic sensors. The DST arrival times have associated measurements errors and resolution limitations, which become more pronounced as the depth interval of analysis is reduced. Baziw Consulting Engineers (BCE) has developed a new DST analysis technique, the so-called DSTPolyKF algorithm, whereby the arrival times of DST data set are used to define a high order polynomial. The main advantages of this new technique are four-fold: 1) the ability to utilize all arrival time estimates irrespective of measurement errors. 2) the ability to analyze the data with user specified and even small (≤ 0.5m) depth intervals. 3) the ability to apply sophisticated data fusion for significantly more accurate DST interval velocity estimation. 4) the use of polynomial regression accuracy parameters to quantify how well the “best fit” polynomial fits the acquired arrival time data sets. This paper outlines the mathematical details of the best fit polynomial where a Kalman filter formulation is implemented. The performance of the DSTPolyKF algorithm is demonstrated by processing real DST data sets.

Oct 1, 2022

By Matt Sotirin

The Santa Fe train station and passenger rail platform were constructed in the downtown district of Fort Madison, Iowa, over a century ago. This landmark building and rail platform were in need of major renovations and rehabilitation in order to restore the site to a functioning railway train station. A multitude of key players from various public and private parties were involved in the design and construction of this project site. Part of the project consisted of constructing the passenger platform. The original design included helical piles to provide foundational support for the platform. Challenges occurred during construction due to the presence of an obstruction in the form of a poured concrete slab in the immediate area where the helical piles were to be installed. The contractor worked with the engineer of record and other consulting parties to value engineer the helical pile design and utilize self- drilling micropiles as a replacement to the specified helical pile system.

Oct 1, 2022

By Walter Campos, Yuri Gallegos, Sául Vigil

El proyecto Educación Digital Rural ha sido analizado con instrumentos de corte cuantitativo, a través de la aplicación de encuestas a docentes y personal directivo de escuelas del área de influencia directa de Minera las Bambas; además, del uso de la técnica de análisis documental sobre el estado de las matrículas y situación final de estudiantes en el año 2020 y 2021 (Hernández et al., 2020). Los resultados muestran que la intervención ha evidenciado la importancia de tener el personal capacitado sobre el aprovechamiento de las tecnologías digitales en el proceso educativo y sobre la intervención clave del liderazgo del directivo para orientar el trabajo docente y asegurar condiciones que permitieron dar continuidad al servicio educativo en las II.EE. rurales de Fuerabamba, Huancuire y Pamputa.

Sep 30, 2022

By Yaming Chen, Gerry Papini

This paper presents a case study of three-dimensional groundwater modeling of a proposed open pit at a gold mine project with historic flooded underground (u/g) mine workings in British Columbia, Canada. The modelling approach for dewatering the open pit included passive dewatering by draining water under natural hydraulic gradients and active dewatering by using active dewater wells, together with residual water drains. Target water level drawdowns behind the pit wall were used to determine the number and depths of dewatering wells to meet the slope stability requirements and in estimation of pit inflow rates. Conceptualizing the u/g mine workings and assigning appropriate flow boundary conditions throughout the life of the mine posed some unique challenges.

Sep 30, 2022

By Natalie Swan, Carlos Santana

La ejecución de programas de monitoreo biológico es un desafío para la gestión ambiental de proyectos mineros, principalmente por la alta demanda de recursos y tiempo que requiere y la poca certeza sobre sus resultados. Por ello, se presenta el uso del ADN ambiental como una alternativa de calidad y probada eficiencia. La aplicación de análisis de ADN ambiental en un programa de monitoreo implica tener en cuenta aspectos sobre la ecología del ADN ambiental, las etapas requeridas para su análisis y el estado de desarrollo de las distintas aplicaciones existentes.

Sep 30, 2022

By Juan Rojas

Chile y Perú ofertan el 40% del cobre de mina en su mercado y cuentan con más del 30% de las reservas conocidas en el mundo. Por tanto, su forma de hacer minería está viviendo un momento crucial. La industria de las comunicaciones, la electromovilidad y la energía verde le abren espacios enormes para su crecimiento futuro. Los factores críticos de éxito son la excelencia operacional, la minería inteligente y la certificación ambiental. Precisamente, los requisitos de la minería 4.0.

Sep 30, 2022