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By Haoran Zhang, Chu Ho

A recent design-build project in New York involved various degrees of additions and improvements to four existing transit stations. Reuse of the existing foundations was considered a more sustainable alternative than constructing new foundations for the project. This approach mitigated the extent of demolition work and limited the amount of downtime for track operations. A key challenge for reusing the existing foundations was the lack of as-built drawings. In order to obtain some measure of confidence for the proposed foundation reuse, non-destructive investigation technology was adopted to evaluate the structural integrity of the piers and foundations. A total of 47 piers for the existing passenger platform were investigated for possible reuse. Several test pits, excavated to verify the foundation type and configuration, indicated the piers were founded on a combination of shallow footings and drilled shafts. Pile integrity tests were performed to verify the length of the drilled shafts. Geotechnical capacity of drilled shafts was evaluated for side friction and end bearing resistance, and confirmed using a proof load test conducted from the existing platform structure. This paper presents the investigation methodology and discusses the approach adopted for geotechnical design of the existing foundations for reuse.

Sep 8, 2021

This manual provides basic practical instruction on the inspection of driven piles. It covers the essential components of pile driving, such as the pile driving hammer, hammer accessories, the pile and soil, and frequently encountered test methods in an uncomplicated, yet knowledgeable, and practical manner. Insight is given into the methods of installing the foundation, dealing with the cranes which do the lifting, the hammers which do the driving, the leads that guide the hammer and pile, the compressors which provide the external power when required, and finally prevalent analysis tools and testing instrumentation and procedures which enable you, the Inspector, to do your job. This DFI Inspector's Manual for Pile Foundations will help the Pile Inspector who has limited knowledge of pile foundations. Perhaps this Inspector has been pressed into service at a moments notice; a few helpful hints and suggestions to him are desperately needed and he can look here for the basics. It is also useful for the experienced Pile Inspector as a reference guide. However, this manual is not a detailed check list of every possible scenario and detail which could ever be encountered. There are other sources available which give more detailed descriptions (and should be consulted by the Inspector when appropriate; a list of this additional reference material is provided and suggestions made in appropriate chapters of this text). The current manual is more a brief "textbook overview" with some of the more important aspects given at least some emphasis so that the Inspector has some direction and hopefully helps to produce a safe, yet economical, foundation.

Jan 1, 1997

By Steven R. Ahlfield, Ali Ghandeharioon

A wastewater treatment plant commissioned in 1978 is undergoing a major expansion. Planning various phases of the 8-hectare expansion at this site requires an understanding of the site response during and after construction, and the potential impact on adjacent properties and infrastructure. The expansion project requires nominally 5 m of site grading fill for flood protection. The site is underlain by loose to compact fine sand over firm to very stiff clay stratum that extends to great depths. Ground improvement is required to mitigate the liquefaction hazard in the fine sand stratum, and preloading is proposed to reduce post- construction settlements in the deep clay. Site development and foundation systems for the plant expansion project were evaluated by conducting settlement analyses which accounted for the historic and future site loading and 3-D modeling of soil layers with interpolation between borehole and cone penetration test (CPT) locations. The numerical model was calibrated to match short-term and long-term settlements measured at the plant site. The analyses were carried out to assess the effects of past loading, proposed preload and surcharge heights, lateral extents and durations as well as vibro-replacement ground improvement on post-construction settlements. Two design options were considered for the preload footprint across the site and foundation system for proposed facilities. It is shown that limiting the preload extent and founding some of the proposed structures on deep friction piles reduce the predicted settlements of adjacent infrastructure and result in reasonable performance for the proposed facilities. INTRODUCTION A wastewater treatment plant commissioned in 1978 will be replaced with a new plant on an undeveloped portion of the site to provide wastewater treatment for an expanded service area. The existing facilities must remain in operation until completion of the new plant. The site grade will be raised nominally 5 m for flood protection. The large areal extent of the site grading fill and plant structures will cause stress changes extending to great depths in the underlying soils and result in settlement of the existing and new structures. Historic settlement of the existing facilities has been tolerable for plant operations, but no settlement performance data was recorded during site development and post-construction from 1978 to 2007. Development of the 8-hectare expansion at this site is planned in three phases to reduce the overall construction schedule. Planning for each phase requires evaluating the effects of various site development activities from start to completion of expansion and during the design life (i.e. post-construction period), and the potential impact on existing wastewater treatment facilities and adjacent properties and infrastructure including an adjacent viaduct structure. Figure 1 presents the site plan and three distinct site development phases considered for the plant expansion.

Jan 1, 2019

By Gerald Verbeek, Erick Baziw

Stone columns are used in geotechnical site remediation to increase load-bearing capacity and reduce settlement of foundations. Stone columns also improve slope stability and increase the shear strength of a soil. A very challenging problem is to characterize the in-situ shear wave velocities from data acquired from Downhole Seismic Testing (DST) after the insertion of stone columns. DST is an important geotechnical testing tool for site characterization that provides low strain (<10-5) in-situ interval compression and shear wave velocity estimates, but the postanalysis of seismic data acquired from DST in the presence of stone columns is very challenging due to the resulting complicated in-situ soil conditions. To obtain the right results it is necessary to use an algorithm that incorporates source wave raypath refraction. Starting with the Normal Moveout Seismic Cone Tomographic Testing (NMO-SCTT) algorithm developed some years ago, this paper outlines the modifications and additions made to this NMO-SCTT algorithm to facilitate stone column site characterization. To dramatically reduce the optimal solution space for the estimated interval velocities the paper also described a priori conditions that are applied based on the unique nature of the stone column site conditions.

By Steve Davidow, Ashely E. Evans, Peter M. Kandaris

"Annually thousands of deep foundations are constructed across North America supporting high voltage transmission line structures. However, a recent state of the practice survey by the Deep Foundation Institutes’ Electric Power Systems Foundation Working Group discovered that the electric power utility industry lacks consistent foundation design guidelines. The survey identified a wide variability in design assumptions, a minimal understanding of risk based analysis, and a need to standardize design methodologies. This paper summarizes the state of practice in electric system foundation design and proposes a framework for risk-based foundation design by accounting for uncertainty from both loads and resistances. Loads derived from electric system codes do not necessarily provide a compatible level of reliability for the design of foundations, as they are a mixture of probabilistic and deterministic values. Load uncertainty is derived from variability in weather conditions, structural models and material properties, typically accounted for by code derived overload factors. Resistance uncertainty arises from variability in natural soil properties, resistance models, subsurface construction techniques, material sampling methods, and limited observations. A consistent methodology is offered relating nominal resistance capacity (strength) to structure loads and service state criteria. Discussion also includes the need for risk-based assessments to account for non-structure load influences (fluvial loads, scour ground loss, liquefaction, etc.).INTRODUCTIONNearly 40 years ago the Electric Power Research Institute (EPRI) embarked on a major research effort to optimize reliability and economics of transmission line foundation design. Strategies focused on improvements in design models, site characterization, exploration strategies and testing to reduce uncertainty and variance in analysis. Transmission line engineers realized that safety and reliability advancements in design based on probabilistic approaches, with a focus on the unique nature of transmission line, could better control risk and cost.Some transmission line professionals took full advantage of these advancements, particularly where research led to improved software and models. Yet, even after two decades of extensive research, by 1995 the industry still had made little progress in changing design habits. The majority of designers were still characterizing sites via deterministic methods, using loads that may or may not relate to a consistent probability of occurrence, and applying a traditional global factor of safety approach (Phoon, et al. 1995). The following two decades have seen even greater developments in software and reliability-based analysis methods, but old habits seem to die hard as recent surveys show less than half of design professional quantitatively assess risk in their design process."

Jan 1, 2017

By Susan Rafalko, Mike Walker, John Sankey, Sherif Aziz, Alex Potter-Weight, Mary Nodine, Frederic Masse

"After several successful projects on the Garden State Parkway and New Jersey Turnpike for support of single-stage MSE (Mechanically Stabilized Earth) walls using rigid inclusions (Controlled Modulus Columns) as an alternate to two-stage MSE walls and surcharge, the Bass River Bridge Widening project presented additional challenges in terms of soil conditions and height of embankment that created opportunities for the design-build ground improvement contractor and its MSE wall-designing partner to enhance their design and construction methods. The specialist contractor decided, in association with the wall system supplier, to perform an independent large scale instrumented test area on the project to demonstrate the ability of the design techniques to model the behavior of the system, as well as the capacity of the rigid inclusions to provide the necessary bearing capacity and settlement control to allow the construction of the highway without any consolidation period. This paper presents a detailed description of the design of the ground improvement system and MSE wall system, as well as the results and conclusions of the monitoring data gathered on the large scale test program. The combination of rigid inclusion ground improvement technologies, such as the CMC system, together with an MSE wall system allows for the rapid and economical construction of high embankment without waiting for a surcharge and consolidation period or the necessity to use a two-stage wall system. In-depth understanding of the design techniques and advantages of this combination will be provided and should be beneficial for any geotechnical engineer or owner looking for innovative solutions to save both time and cost on their projects.1. IntroductionAs development continues on sites with poor ground conditions throughout the world, conventional MSE walls remain a flexible design solution; however, construction of MSE walls in combination with ground improvement is becoming more frequent where extreme differential and/or total settlement prevail due to soft ground conditions. Various techniques have been used in the past in such conditions (e.g. conventional surcharge, staged construction, or two-stage MSE walls), even though these design solutions have typically involved longer waiting times for settlement to occur. As a result, conventional MSE wall design has been combined with a variety of ground improvement techniques consisting of rigid inclusions for an economical and efficient solution with the potential to accelerate construction and limit long term settlement. For the particular subject of this paper, the specialist contractor (Menard) proposed to use CMCs (Controlled Modulus Columns) to support the highest part of the MSE wall. CMCs are grouted displacement rigid inclusions installed in a grid-like pattern using a displacement auger. Before the CMCs are installed, a working platform may first need to be placed to allow equipment to move around the site depending on the ground conditions. Following the CMC ground improvement, an LTP (Load Transfer Platform) is installed prior to the construction of the MSE wall."

Jan 1, 2015

By Alessandro Bertero, Dylan Pearson, Wesley Schmutzler, Matteo Bertoni

"The SR 83/US 331 highway is located in the Florida panhandle, where it connects the Walton County beaches to the I-10 corridor. The roadway is of vital importance to the economy of the area as well as its safety since it represents the primary hurricane evacuation route from southern Walton County. The Florida Department of Transportation (FDOT) decided to increase the number of traffic lanes from two to four and improve the geotechnical properties of the moderately deep, very loose foundation soils, that had affected the highway rideability for years. The soil mixing was selected as the method to meet the unique deep ground improvement challenges of the project. The design required that Shallow Mixing Method (SMM) be used to build a 10-foot thick platform that transferred axial load to the bottom soil layers through a series of Deep Mixing Method (DMM) columns. Upon completion over 8,300 SMM columns and 1,500 DMM columns had been installed, with no remedial work required. Also, only 1% of the almost 1,500 specimens tested did not meet the specification requirements. This paper will describe the challenges encountered and provide valuable information that may be useful for other future projects, including details not previously published.INTRODUCTIONThe counties of Walton and Okaloosa have been a very popular vacation destination for many ears. The 50-mile long coastline boasts beautiful, sugar-white beaches and waters the color of emeralds. The popularity of the area has been growing even further, over the last few years. A consequence of this phenomenon is a fast-paced increase of the traffic flow on the SR83/US331 highway, especially at the bridge that connects the Walton County beaches across Choctawhatchee Bay (Fig. 1) to the heavily traveled I-10 corridor. The highway plays a very important role for the area also as a commercial link and as the primary hurricane evacuation route from southern Walton County. The increase in traffic has produced higher travel time, when not a complete traffic paralysis, and exacerbated the issue of ground settlement where accelerated wearing of road foundation occurred due to the presence of very loose, moderately deep, soils, that had afflicted the highway for several years. The Florida Department of Transportation (FDOT) decided to put an end to these issues by increasing the number of traffic lanes from two to four and improving the geotechnical properties of the foundation soils. The Design-Build Maximum Price Request for Proposal (RFP) issued for the expansion of the Choctawhatchee Bay Bridge saw the participation of numerous D/B teams which produced various technical solutions. Among them, the FDOT selected the Skanska/Parsons Brinckerhoff (General Contractor) proposal which provided for the use of soil mixing as the ground improvement technology. The design/build team assigned Foundation & Geotechnical Engineering (Designer of Record) the ground improvement design which Treviicos South (Specialty Contractor) would execute."

Jan 1, 2017

By A. Flora, E. Bilotta, F. Foria, V. Nappa

"All the typical applications of deep mixing rely on the good mechanical properties of the improved columns to strengthen or stiffen the ground for a number of geotechnical applications.This paper focuses on a completely different kind of deep mixing, carried out in order to obtain columns much softer than the surrounding soil. This kind of deep mixing, named Soft Deep Mixing (SDM), is introduced as an original means to tackle seismic risk, and can be convenient when the existing structure to be protected has a historic relevance that cannot be altered with structural modifications. The idea is that properly assembled layers made of partially overlapped SDM columns, with dynamic impedance much smaller than that of the surrounding soil, will filter and reflect most of the seismic energy.The paper presents the results of some 2D parametric numerical analyses aimed to investigate the seismic performance of this innovative approach. Simplified dynamic inputs (Ricker wavelets, having only one largely predominant frequency) were adopted to better understand the effect of signal frequency. The analyses show that the effectiveness of the soft grouted isolating barrier depends on soil and SDM geometrical, physical and mechanical properties, as well as on the frequency content of the seismic input.INTRODUCTIONPassive structural systems installed at the foundation level of existing buildings are a common solution to protect them against earthquakes. However, installation procedures are expensive and not always feasible, as for instance in the case of valuable buildings. As an alternative, ground improvement techniques can be used to modify ground properties, in order to mitigate the intensity of shaking at ground level. The propagation of shear waves in the ground can be modified by introducing a layer of artificially modified material, having a dynamic impedance (defined as n =p VS, where p is the material density and VS the velocity of shear waves) very different from that of the natural soil. Both very high or very low values of the dynamic impedance of the grouted soil (nt) can be effective in reducing the overall transmitted energy, with the difference that – for a given reduction of the transmitted energy - stiff grouted layers tend to filter the low frequency components of the amplitude spectrum without modifying in a significant way the high frequency components, while soft grouted layers have the opposite effect. Then, ideally the choice of the best grouting technique should be made considering the effects of the different frequency components on the building to be protected. These effects are detrimental for the structure when they are close to its natural frequency: high frequency components result into large structural loads on massive squat structures (high natural frequency), and low frequency components may be critical for tall and flexible structures (low natural frequency). Therefore, the typical procedure of stiffening the uppermost soil layers regardless of the kind of building to be protected is not necessarily beneficial, and for the case of squat structures soft grouting should be preferred. However, this procedure has not been taken into account yet in the engineering practice, and may pose static problems at ground level (i.e. excessive static settlements)."

Jan 1, 2015

By Julie Shang, Tim Evans, Michael McDonald, Yu Guo, Bingfeng Xue

Effective chemical grouting represents a technical and economic solution to many challenges related to soil stabilization and blocking the flow of water. Chemical grouts are facing increasing demands in durability, environmental impact and value. To better meet these challenges, a novel and cost effective process was developed to produce a sodium silicate that increases the ratio (i.e. silica to alkali) beyond what has been used in traditional silicate-based grouts. The move to a lower sodium form of silicate was anticipated to have two desirable performance enhancements; a reduction in leachable sodium and improvement in the durability of the silicate grout. An in-depth study was performed at the University of Western Ontario Geotechnical Research Centre to quantify improvement in durability as well as other performance properties such as compressive strength. The study began by first modelling the gelation time and reaction kinetics of the high ratio sodium silicate over a range of silicate concentrations using two different setting agents as well as with/without a hardener. As expected, reducing the level of sodium produced a much more water resistant grout. These same formulations also showed a four order magnitude reduction in permeability. Somewhat surprising, test results showed the higher ratio silicate having much higher compressive strength. At the time of this abstract, the high ratio silicate was moving to the trial stage for geotechnical applications while the petroleum industry was further along with several successful field trials for water blocking as well as cement remediation. This paper will review the chemistry, testing and features of this next generation form of sodium silicate. Introduction Sodium silicate based grouts have been used for decades for soil stabilization and water control. Over the years, several silicate-based systems have been tailored for specific application conditions to maximize performance and reduce cost. Past research has also focused on the selection of setting agents and hardeners for silicate grouts. A constant in the development effort has been the grade of sodium silicate. The vast majority of chemical grouts have been formulated using a ~3.2 ratio sodium silicate. As a very brief overview on the meaning of “ratio” and why it is so important to performance properties. The ratio describes the proportion of sand to alkali or SiO2:Na2O used to make different grades of sodium silicate. Comparing a 2.2 ratio to a 3.2 ratio, it is easier to polymerize and set the 3.2 ratio. Upon setting and forming a silica gel, the system has higher compressive strength values and improved durability with a reduced level of syneresis (i.e. shrinkage). This leads to the question if 3.2 is better than 2.2 why not go to 4.2 or higher?

Jan 1, 2018

By Vishal Pathak, Shailesh A. Godhuly

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

Sep 1, 2022

By Abid Adekunte

"In recent years, developers have had to deal with complexities associated with numerous cases of deep basement construction in built-up areas. Design and construction of deep excavation support systems in urbanised zones come with many technical challenges. Restricted working spaces often render the use of temporary struts as wall restraint systems unpopular, as working space needs to be maximised. Also, tie-back anchors are often inapplicable due to the existence of adjacent structures. Therefore, developing alternative restraint systems for deep basement structures in builtup areas is becoming increasingly important to the present day basement engineer.This paper is centred on the design, construction and monitoring of enabling works for deep basement structures on three sites in the United Kingdom and Republic of Ireland. Traditional tieback anchorage and propping systems were inapplicable on the sites. As alternatives, separate novel wall restraint systems were developed and adopted, to enable excavation on each of the three sites.Performances of the novel wall restraint systems, as well as the responses of adjacent structures were monitored. Numerical modelling and field monitoring results show the three alternative wall restraint systems to be safe and effective. The paper also highlights the advantages of the novel solutions over conventional methods.INTRODUCTIONRecently, deep basement structures have become popular components of urban building developments. As pointed out by Pearlman et al., 2004, this could be attributed to the inadequacy of surface parking spaces in urbanised zones, while underground parking facilities are also believed to improve both aesthetic and commercial qualities of urban structures.However, while the incorporation of basement structure into new urban development appeals to developers and architects, the engineering design and construction aspects of basement works typically come against a whole lot of complexities and challenges. As highlighted by Wong, 2002, engineering problems associated with basement construction in built-up areas are numerous, some of these include; complicated sub-soil conditions, dealing with excessive active pressures, complex temporary works, proximity of sensitive adjacent structures, high level hazards to construction workmen and surrounding community, inadequate working space, etc."

Jan 1, 2015

By Qi Wang, Zengzhu Kang, Jianguo Liu, Guanglei Liu

"Due to the increase of automotive vehicles, available parking spaces become a new type of limited resource in central cities of China, especially in those old districts without visionary urban planning. Additional mechanical parking in underground space is an efficient solution to provide parking spaces under the situation where the urban space is constrained. Shichahai district is an old protected zone in Beijing which is close to the Forbidden City and there are many Hutong (alleyway) and Quadrangles (courtyard house). No spaces are available for car parking on the ground and all vehicles are parking in Hutong without order currently. The local government plan to do renovation work for this district and improve the residential environment. Several innovative solutions are studied including parking in deep shafts, parking under existing buildings by under-pinned method, parking under buildings by covered excavation method, parking under roads built together with utility tunnel etc. 5000 difference types underground parking spaces are planned to be constructed in the following three years. Project examples are also introduced in this paper. INTRODUCTIONCar parking resources are very limited in central cities, especially in old districts without planning for increasing automotive vehicle volume. Traffic get worse when cars park on the side of the roads or move slowly to find parking spaces. Investigation shows the normal (parking space/ automotive vehicle volume) ratio is about 1.2 in most big cities such as New York, Tokyo and Hong Kong, while this ratio is only 0.5 in Beijing. One solution is to move cars out of central cities. But there are still huge parking requirements for the citizens living in central cities. Shichahai district is an historic protected zone in Beijing which is close to the Forbidden City and there are many Hutong and Quadrangles (refer to Figure 1 for project location). No spaces are available for car parking on ground and all vehicles are parked in Hutong without order currently. The local government had a plan to do renovation work of this district and improve the residence environment. 5000 different types of underground parking spaces are planned to be constructed in the following three years. One project designed and to be constructed by Zhongyan Technology will be introduced in this paper. Other innovative solutions will be introduced briefly as well."

Jan 1, 2017

By Abdul Aziz Hanifah

A novel instrumentation and analysis technique, called GLOSTREXT method has recently been introduced for bored pile load tests in Malaysia. This technique provides an innovative and improved alternative for conventional bored pile instrumentation methods commonly practiced for the past few decades. Results for five case histories involving full scale static load tests for high capacity bored piles with both new and conventional instrumentation details placed in within the same instrumented piles are presented to demonstrate the advantages of this novel technique. Results show good agreement between the new and conventional instrumentation.

Jan 1, 2006

By C. Dai, S Raathiv

The Waikato Expressway is one of the New Zealand Transport Agency’s (NZTA) seven roads of National Significance. Coffey is part of the City Edge Alliance engaged by NZTA for the Hamilton Section of the project. The 22km Hamilton Section is the largest and most geotechnically complex section of the Expressway. The Mangaonua gully in Sector 6 is the most challenging geotechnical area of the project for piling works. Together Coffey and Brian Perry Civil have carried out the temporary and permanent design and construction of embankments, piling works, retaining walls and soil improvement works for the bridge construction. The design and construction works were governed by weak alluvial layers and artesian pressure layers several meters beneath the ground level. This paper presents the action taken to improve the foundation of temporary platform, control the artesian pressure, prevent bentonite leakages into the highly permeable alluvial layer and challenges in the base grouting process. This paper summarises the key components in the construction and supervision of bored piling works and outlines innovative solutions for challenges which we faced during the construction.

Nov 1, 2022

By Aly M. Mohammad

Croton Point Avenue Bridge carries Croton Avenue over Metro-North main tracks at Harmon Rail Yard in Westchester County, New York. The new bridge is 1100 foot long and 36 foot wide nine span structure with three spans continuous units. The spans are steel multi-stringers, composite with concrete deck. The piers are solid wall piers and the foundations are spread footings. During the design of the bridge foundations it was determined that the relatively loose to medium dense sand layer is susceptible to liquefaction under a design earthquake with a seismic coefficient of 0.15g. Several foundation options were considered for the new bridge including both shallow and deep foundations. It was determined that the most cost effective alternative is to use spread footing foundations supported on densified soils. Vibratory probes were utilized to densify the loose to medium dense sand layer and reduce the risk of liquefaction. Densification test sections were performed to determine the optimum spacing for the vibro probes. The test sections included performing piezocone tests before and after the densification to compare the increase in relative density of the sand. In addition, ground surface settlement due to the vibro probes was measured and correlated to the increase of soil relative density. The paper will present the results of the ground improvement method utilized and correlate the spacing of the vibro probes and the increase in relative density and the results of the piezocone tests performed before and after the densification. It was found that the vibro probes are not as effective as thought at shallow depth below the ground surface. It is believed that the results and finding presented in this paper will benefit both the design and construction industries by providing a relatively cost effective means to improve the soils

Jan 1, 2007

By Viswanadham B. V. S., Babu K. V

Many refineries are in the process of revamping and expanding their existing facilities. Most of the refineries are located in coastal areas due to ease of transportation and storage of crude oil. Considering the criticality of structures as well as prevailing soil conditions, most of the structures are supported on pile foundations. In depth review of sub-surface investigations data followed by liquefaction assessment of the site, it is noticed that site is prone to liquefaction during the seismic event. Among various techniques, driven cast-in-situ piles were selected to mitigate liquefaction. Static cone penetration tests were conducted during the pre and post installation of driven cast-in-situ piles at identified locations. Analysis of cone penetration test data shows that considerable ground improvement has been achieved post-installation of driven cast-in-situ piles.

Sep 1, 2022

By Christian Hoyme, Jochen Maurer

Most of the current foundation projects are suffering from disconnected information silos. In the first silo there is the planning of the project with corresponding data, presented by paper or digital drawings. Here will Building Information Modeling (BIM) be one of the trends for the future. We will see more and more projects leaving the “old way” of 2D drawings and moving into 3D planning including metadata of the foundations. But even with a perfect BIM model of a jobsite, we are not at final end of digitalization. While execution of the project at the jobsite, a second data silo is evolving. Data collected directly from construction equipment and manual measurements is currently undervalued in most projects. Paper is passed to the equipment operator and major data from measurements on site are noted on paper and digitized afterwards. Automatically collected data is not be used to create site progress reports or similar report. So, the real “data” just flows around without connection to any other data already existing in projects. And then the third silo arises: The documentation of the project. Data collected on paper es reentered to create some basic documentation of the work handed over to the client. Spreadsheet software is still the “tool-to-be-used” to create at least some documentation. Finally, the documentation is not connected to the data created while planning and not connected to the automatically collected data from the jobsite. A connected jobsite in the foundation industry must link these information silos and have to create a full data-workflow from the design through the execution to the as-built documentation. INTRODUCTION Building information modelling (BIM) is currently the most popular term of construction business in Germany and probably all over the world. But as often there are many different definitions out there and everyone has his own definition or at least understanding what BIM is about. But for sure it is the most relevant for the construction industry in the near future. Most popular is the digital twin for the upper structure of a building. In most cases the BIM models just shows the building itself, but there is more to be implemented. For example: projects where a special foundation is needed, BIM should include also the foundation elements with meta data. There are several advantages. Not only the clash detection of anchors, but also the possibilities to check the interaction with neighbor constructions, power lines and so on are a use case. For sure most of the special foundation elements are not relevant for the whole lifecycle of a building. But during construction and later the demolition the information about the hidden elements is important and gives a benefit to all stakeholders. In the future there will be not the question: “What is already in the ground?”. The risk for following construction projects on the same ground will be minimized.

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 David S. Graham, Benjamin Turner, Paul J. Axtell

Seismic challenges were at the forefront of design for two parallel replacement bridge structures over the Arkansas River as part of the I-30 Crossing Project in Little Rock, Arkansas. Although not an area of the country typically associated with high seismicity, proximity to the New Madrid Fault Zone resulted in design ground motions sufficient to trigger liquefaction in alluvial channel and point bar deposits. A detailed post-award subsurface investigation program utilized CPT with complimentary borings to obtain samples for laboratory testing to assess the continuity of potentially liquefiable layers, from which we concluded that continuous zones of liquefaction across the extent of the north approach could lead to lateral spreading towards the river. An overview of the foundation and superstructure design to resist lateral spreading forces in accordance with the latest published design guidelines and research is presented. Other seismic aspects of the design are covered including timber pile ground improvement to mitigate liquefaction at the north approach embankment and foundation input motions that differ from code-based ground surface motions due to foundation stiffness, strength, and geometry. The project showcases an example of successful collaboration between geotechnical and structural designers with contractor input to address seismic challenges in the South Central US. Furthermore, the importance of considering kinematic demands on columns and other superstructure components – not just foundations – is highlighted.

Sep 8, 2021

By Glenn J. Rix, Eduardo Tavera, Raphael Siebenmann, Zhongjie Zhang, Robert C. Bachus, Jongwon Jung

"The Louisiana Department of Transportation and Development (LADOTD) uses a variation of the FHWA-modified Gates equation to verify the nominal pile bearing resistance, typically on smaller projects where static load tests and dynamic monitoring are not practical. An inconsistency in the resistance factors for load and resistance factor design (LRFD) penalizes the target pile capacity needed during field observation if the LADOTD dynamic formula equation is used, which is unreasonable, and has created confusion among designers, consultants, district personnel, and inspectors in Louisiana. The objectives of this project are to recalibrate the FHWA-modified Gates equation and update the associated LRFD resistance factor for pile types and local soil conditions encountered in Louisiana. Improved consistency relative to the current design approaches will be achieved if the updated resistance factor matches or exceeds the worst-case resistance factor used by LADOTD, which will reduce confusion among users. Updating the resistance factor will also serve to increase confidence in the FHWA modified Gates equation, optimize the efficiency of the piles, and reduce project costs.IntroductionThe original 1957 Gates pile driving formula (Gates, 1957) is an empirically derived dynamic formula that is used to predict pile capacity in the field during pile installation. The original Gates formula tends to over-predict pile capacity for low driving resistances and under-predict pile capacity for high driving resistances (Hannigan et al., 1998). Thus, the Federal Highway Administration (FHWA) proposed a modified version of the Gates formula that addressed this limitation. The FHWA–modified Gates equation is:"

Jan 1, 2017