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By Terzis D. PhD, Katterbach M.

While awareness around the environmental impact of existing grout materials and chemical binders is increasing rapidly, biotechnologies are growing traction as sustainable alternatives in groundwork operations. Herein we present the principles and application methods of bio-grouting. The term is used to describe a system which is based on soil, groundwater or marine enzymes which are able to catalyze the production of calcite replicating a natural phenomenon. The system’s end result are mineral crystalline bridges which act as binders to improve the geotechnical properties of soils. This paper presents a comprehensive description of bio-grouts, their underlaying mechanisms contributing to mineralization as well as environmental considerations. With their water-like rheology, bio-grouts have a wide application range and are minimally invasive, requiring only very limited injection pressures. The equipment is the same as that used in conventional cement grouting, and the reactant components are worldwide available or easily suppliable, which explains why bio-grouting has nowadays become a valuable and sustainable alternative towards efficient soil treatment. Recent developments in the last years have allowed to further increase the applicability and efficiency of bio-grouts to ultimately bridge the gap between research and practice. A case study is illustrated in this paper showing the successful implementation of bio-grout for the stabilization of weakly cemented sandstone to safeguard an adjacent road segment in Switzerland

May 1, 2022

By Jack Taggart, Chris Barker

Pile load testing strategies for large infrastructure projects and multi-phase building developments have historically justified cost and programme benefits for undertaking advance preliminary and working pile load testing. However, more recently piling and pile load testing strategies have included assessment of the embodied carbon to understand and present the carbon savings that can also be achieved. This paper gives an overview of the factors contributing to carbon and emissions in the construction of bored pile foundations and presents the methodology taken in assessing embodied carbon as part of the pile load testing strategy for a multi-phased building development in London. Potential embodied carbon savings for various bored pile types and load testing strategies are discussed alongside alternatives and other considerations including pile re-use and carbon offsetting to inform continual improvement for future projects.

May 1, 2022

By Marcel Bielefeld, Joost Bakker, Rob van Dorp

Pile load testing can be performed by a static, rapid or high strain dynamic (generally designated as dynamic) testing method. The static load test is often considered the “gold standard” of testing with the other methods merely ‘alternatives’. However, the rapid load test, as a quasi-static test, has all the positive elements of the static alternative: the direct measurement of loads and displacements. Moreover as stress wave phenomena have no influence, the interpretation of rapid load test results is more straightforward than that of dynamic testing, and also independent of the person performing the interpretation. This paper will explore the Rapid Load Testing method and illustrate the advantages and limitations through a case study in Rostock, Germany

May 1, 2022

By Pratter P., Boley C.

Polymers are well established in geotechnical applications, for example in ground improvement, where the polymers act as a binder that, when cured, holds the grains together by adhesive and cohesive forces. The subject of this research work is an innovative composite of polymers and gravel, which differs from conventional grouting materials due to its adjustable material properties. With these specific properties, the semi-rigid material can be optimally adapted to the local ground conditions and the individual framework conditions of a construction project. For the characterization of the composite material, stateof- the-art methods, such as image processing by segmentation, are presented. Segmentation is suitable for quality assurance and monitoring of laboratory samples and soil samples directly from ground improvement on the construction site. The load-bearing capacity of the innovative material can even be increased to the order of magnitude of concrete. For this reason, the soil mechanical laboratory tests in this research had to be modified and even expanded by rock mechanical laboratory tests. Based on the experimental investigations, the importance of this innovative material for practical application is demonstrated by a calculation example from construction practice, which shows that even difficult ground conditions can be handled with it.

May 1, 2022

By Rajasekar Subbian, Jessica Oudhof

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

May 1, 2022

By Torsten Wichtmann, Jan Macheck, Frederik Broz, Patrick Staubach, Hauke Zachert

The majority of heavy or strongly loaded structures, for instance high-rise buildings, large span bridges or gas storage tanks are founded on pile groups. However, current design codes and guidelines do not provide a standard procedure for their design under lateral dynamic and high-cyclic loading arising from e.g. wind, temperature or earthquake loads. To establish appropriate design strategies, a better understanding of the pile-soil, pile-pile and pile-cap interaction is required. This paper is focused on finite element backcalculations of centrifuge tests on single piles and pile groups subjected to up to 500 lateral load cycles. For the finite element simulations, a special calculation procedure is applied, combining two kinds of constitutive models, a conventional (Hypoplasticity with Intergranular Strain extension) and a special highcycle accumulation (HCA) model. The parameters of the constitutive models are calibrated based on static and cyclic laboratory tests on the sand used in the centrifuge tests. The performance of the applied numerical procedure is evaluated based on a detailed comparison of the simulation results with the measured data from the centrifuge tests. Overall the applicability of the used numerical strategy for simulating the behavior of pile groups subjected to high-cyclic loading is shown.

May 1, 2022

By Packer M. L

Residual load development in driven precast piles has been widely researched in recent decades, however, cast-in-situ piles are often falsely assumed to be unaffected by this mechanism. In contrast to driven precast piles, driven cast-in-situ (DCIS) piles require adequate time prior to loading for the concrete hydration and curing processes to occur. The concrete-soil interaction is complex with several processes influencing the strains within the concrete pile after installation. DCIS piles are of particular interest given that residual loads can be developed during both the driving and casting phases. This paper present four instrumented end-bearing DCIS piles in which temperature and strains were monitored from installation, with the objective of identifying the processes contributing to the measured strains prior to testing. Strain gauges at all depths recorded a net compression and compressive strains continued to increase up to the commencement of load testing. Residual strains in the test piles were interpreted to be influenced by temperature (concrete and ambient soil and air temperature), consolidation of soils due to dissipation of excess pore water pressure, and swelling from absorption of groundwater. Several residual load interpretive methods are evaluated with the Siegel and McGillivray (2009) approach being consistent with the skin friction full mobilisation theory of the Unified Design method. The full-scale field tests presented herein provide a unique opportunity to examine DCIS pile behaviour, particularly given the lack of presently available published studies on these pile types.

May 1, 2022

By Prof. Dr. -Ing. habil. Sascha Henke, Johannes Beck

The growth of Building Information Modeling (BIM) during recent years opens possibilities for integrating new digitally driven design approaches. While parametric design and algorithmic design slowly gains popularity in numerous ACE-applications, e.g. bridge design, it is rarely used by geotechnical professionals. This article presents an approach for implementation of parametric design in the BIM-based geotechnical design process. The methodology is applied to pile design and enables a real time design analysis according to DIN EN 1997-1 and EA-Pfähle 2012 considering boundary conditions such as pile position and layout, pile geometry, soil stratification and soil properties. By using intelligent attributes and scripts to control, calculate and assign them, the design analysis is directly executed in the BIM-software environment, in this case Autodesk Revit with Dynamo. This BIM integrated design approach allows multi-criteria evaluations of pile designs using aspects such as costs, environmental impact or constructability in addition to the commonly examined structural analysis criteria. As the proposed models are fully parametric, generative optimization algorithms can be applied to identify the ideal design for the entirety and each of the piles. Finally, the potential and limits of this methodology with respect to modeling, analysis, simulation and optimization are discussed.

May 1, 2022

By Mohamed Hassan, Matthias Seip, Steffen Leppla

In the east of Frankfurt am Main, Germany, a new high-rise building is planned directly next to the river Main. The high-rise building will have a height of about 75 m and will be founded on a Combined Pile-Raft Foundation (CPRF) in the tertiary marl. The new structure will be constructed next to important, sensitive traffic infrastructure. The foundation of the new high-rise building adjoins directly existing historic quay structures, which are more than 100 years old. For analysis of the stability and the serviceability of the heavily eccentric loaded foundation of the new high-rise building and the existing structures and for the investigation of the soil-structure interaction complex three dimensional, non-linear numerical simulations have been carried out. These numerical simulations take into account all geometric and material specific boundary conditions, including the history of the construction of the whole area. The paper introduces into a very complex construction project in which the investigation of the soil-structure interaction has an important role. The three-dimensional numerical simulations are explained and the results are shown.

May 1, 2022

By Peter Faust, Peter Hubbard, Kenichi Soga

The European Federation of Foundation Contractors (EFFC) and The Deep Foundations Institute (DFI) have set up a task group to compile a Guide for Working Platforms. The first edition of this Guide has been published in January 2020. The aim of the Guide is to provide reliable methods for design, testing and verification of working platforms for construction equipment, especially in the deep foundation industry where track loads can be excessive due to the nature of its operations. The Guide has identified areas where knowledge is limited. Actual track pressure and its distribution along the length of the tracks is still not well researched. Current recommendation provided in EN 16228-1 are believed to be overly simplified and may lead to conservative requirements for working platform thickness. This paper presents results of a series of field tests where the actual track pressure of a large drilling rig during operation was measured in real time together with the deformation of the working platform. Embedded, distributed fiber optic sensing (DFOS) at different depths throughout the platform allowed for a three-dimensional evaluation of the platform deformation throughout the entire operation. Results will help to develop more reliable recommendations for future safety requirements of working platforms for deep foundation equipment.

May 1, 2022

By Matthias Pulsfort, Jiarui Du, Torsten Wichtmann, Achim v. Blumenthal, Diethard König, Rowena Verst

The influence of the interaction between support fluid and soil, e.g., filter cake formation, on the shear stress transfer in the soil-concrete interface of diaphragm walls and bored piles is still controversially discussed. Actual research on the soil-concrete interface using bentonite suspensions indicates that shear stress transfer is underestimated by existing standards. Investigations on the soil-concrete interface using polymer solutions are rare. Therefore, complementary field investigations and systematic laboratory studies were conducted to analyse the soil-concrete interface using both bentonite suspensions and polymer solutions. Thickness and composition of real-scale filter cakes were investigated on several slurry wall construction sites, where bentonite suspensions were used. Direct shear tests (60 mm x 60 mm) were executed for soilbentonite mixtures with varying amounts of bentonite and different granular fines representing a realistic bandwidth of in-situ filter cake compositions. Larger direct shear tests (300 mm x 300 mm) with preceding horizontal penetration, subsequent vertical tremie concrete placement, and filter cake consolidation were performed using both bentonite suspensions and polymer solutions. The results support the view that shear stress transfer in the soil-concrete interface can be described by a wall friction angle in a range of 25° to 30° for bentonite suspensions and between 35° and 40° for polymer solutions in non-cohesive soils.

May 1, 2022

By Scott White, Pishun Tantivangphaisal, Andrew Bell, Chris Barker

There has been considerable advancement in recent years in the tools, both software and hardware, available to allow efficient digitalization of site records during the construction of geotechnical works. Whilst these tools have excelled at replacing handwritten records, the ability to use digital records to validate design and construction requirements in real time or even within reasonable timescales has generally been limited to the development of bespoke ‘prototype’ project specific solutions. This paper describes the development and implementation of an industry standard design schedule and the benefits of the broad adoption of a single database schema for data recorded on geotechnical sites. The former has brought significant improvements and automation of the design process, whilst the latter has enabled the validation of the constructed works against design intent in almost real time. Further details of the standardized design schedule, already publicly available in the UK through the FPS, examples and lessons learnt from implementing digital site record systems on live projects are presented herein. The utilization of cloud computing technology and complex algorithms linking plant/rig instrumentation with design data can further automate construction sites using IoT (Internet of Things) best practices. The authors will share their experience of the recent deployment of a digitalized design-to-construction record system, give recommendations for future development and a call for an industry wide drive to finalize and adopt the AGS Piling data schema.

May 1, 2022

By Steffen Schweizer, Tadeusz Brzozowski, Alfred Koller, Michał Topolnicki, Jürgen Wäger, Grzegorz Sołtys

A full scale test has been conducted to determine ground bearing pressure under rig tracks. The track loads were recorded in real time using Liebherr's Ground Pressure Visualisation system, and the vertical stress induced in the ground was measured with pressure cells embedded in the ground. It has been found that the recommendation of EN 16228 regarding determination of the track length is oversimplified. The contact length should dependent on the susceptibility of the working platform. It has been also demonstrated that the corrected pressure distributions under the tracks influence the dimensioning of the working platforms. As a result, the designed working platform may actually be less secure than is shown by conventional calculations.

May 1, 2022

By Robert Thurner, Albin Norrman, Sami U. Raja

The West Link is a double track railway project currently under construction in Gothenburg, Sweden. The project includes the construction of 8 kms of track, 6 kms of which will be in tunnels. Beside several large excavations, three new stations will be built: Centralen, Haga and Korsvägen, all within the city of Gothenburg. The first construction phase of the project began in May 2018, and the finalization of the project is expected in 2026. The project is divided into five sections. Keller is involved in four of these contracts since the design & planning phase in 2018 assisting the special foundation works with various geotechnical techniques including Dry deep soil mixing (DDSM), jet grouting, rock grouting, uplift piles, sheet piling and rock dowels. The core idea behind successful collaboration has been to apply the right product for a location specific challenge which can help optimise costs & time for the project with a minimal environmental impact. Due to the extensive nature of the project, a team of experts from various locations around the world is helping design and execute various foundation technologies and providing solutions to the practical challenges in the project like working close to existing structures, rail lines, river etc.

May 1, 2022

By Vijayakumar Viramuthu, Martin Heinrich

Tower of Lot L, L1 & M, Kuala Lumpur City Centre when completed would stand 700 m tall. This Mega tall Skyscraper would merely be less than 500 m away from the world tallest Twin Tower, the Petronas Twin Tower. From June 2018 to February 2020 BAUER (MALAYSIA) SDN. BHD. constructed 225 nos bored piles with diameters of 2.0 m and 2.5 m for this tower. To comply with the depth requirement of the initial design and the need to have the pile toe 2.0 m above competent bedrock, the drilling equipment was required to be able to achieve a maximum drilling depth of 150 m. Actual piles constructed on site were deeper than 120 m. These dimensions caused superlative challenges which included but were not limited to controlling the open borehole stability over time with polymer, installing 70 t heavy steel cages and pouring up to 550 m³ concrete continuously in conjunction with installation of 88 t heavy kingposts into workable fresh concrete. The piling works were executed with one BAUER BG 48 and one BG 72, the biggest drilling rig globally available.

May 1, 2022

By Bastian Hoffmann, Christian Moormann

The paper presents results of an experimental study on the axial load bearing behavior of vibratory driven full displacement piles in comparison with impact driven and cyclic quasi-static installed piles in dense sand. The test setup and the measurement devices used to this end are explained. Subsequently, the results of the axial loading like load settlement curves are shown and the impact of the installation method is interpreted. The results presented in this work are mainly based on three installation methods: test series one investigates axial behavior of vibratory driven piles, test series two describe the same cyclic pile installation process but without dynamic influence wherein a special test setup developed to install the piles cyclic quasi-static in the soil was used. A third test series carried out using the conventional impact pile driving method served the purpose of not only comparing the results against vibratory driving, but also aided in isolating the effects of dynamics inherent to the vibratory driving process.

May 1, 2022

By David A. Hart, Barry P. Osborn, Richard J. Totty, Ana T. Carvalho, Max B. Elliott

This paper addresses the experience designing and installing bored piles for the King’s Cross area. This includes continuous flight auger and rotary bored piles, with a range of diameters between 600 mm and 1200 mm, reaching a maximum depth of 56 m below ground level. Existing Network Rail Thameslink twin bored running tunnels are located directly beneath the subject plots. These tunnels have an external diameter of 6.6 m and the crowns of the tunnels are very shallow, in some cases just 10 m below the existing ground level. Some plots needed piles to be installed in close proximity to the tunnels, which required additional control measures and contingency plans. Pile verticality was monitored as the tip of each pile advanced and in-tunnel monitoring readings were verified and are presented. Lessons learned from designing, installing and testing the piles and monitoring the tunnels are addressed in this paper.

May 1, 2022

By Brandon M. Robinson, Osman F. Besler, Dominik Gaechter

The Sandbukta-Moss-Såstad (SMS) project is a part of the Intercity development project, which is part of the largest transport project in Norway, consisting of 270 km of new double-track rail. The SMS project consists of 10km of double-track railway including three open stretches and two tunnels. Soil conditions consist of quick clay underlain by Bedrock. Dry soil mixing (DSM) was considered as the main soil improvement method to allow for excavation of the quick clay and construction of the D-Wall panels. The preliminary design revealed around 25,000 ton of binder installation. Therefore, a test field has been conducted to evaluate binder alternatives in means of improved soil strength by considering CO2 emissions. Multicem and Standard cement (Standard FA) have been compared for that purpose. Multicem is a type of binder which mainly consists of Portland cement and cement kiln dust (CKD). CKD is a fined-grained, solid, highly alkaline material removed from the cement kiln exhaust gases. reverse column penetration test (FOPS) and pre-drilled column penetration test (FKPS), which are common tests to evaluate DSM strength have revealed comparable strength outcome for both binder types. Therefore, Multicem has been selected as the main binder type to be used further which provided a reduction in CO2 footprint of up to 40%.

May 1, 2022

By J. E. De Waele, J. J. Lee, M. J. Mulheron, Luke R. Deamer

There is increasing demand for geotechnical contractors to commit to carbon reduction, net zero or science based targets. A lot of focus has therefore been placed on using low carbon materials and low emission rigs. However, whilst these are ways to help reduce carbon, there is a need to look beyond just substituting materials and fuels to meet net zero. Using the IEMA carbon hierarchy, there is a need to first look at eliminating and reducing emissions, before considering substitute materials. For example, in geotechnical designs, this may mean considering using ground improvement or reducing the number of piles, before considering using low carbon cements. Equally, for remaining emissions, this hierarchy means considering carbon negative products to offset emissions, such as ground source heat pumps. This hierarchy can also be applied throughout geotechnical contractor organisations. For example, considering video conferencing for meetings, before considering public transport or using an electric vehicle. This article explores the carbon hierarchy and how it can be applied to all areas of a geotechnical contractor’s business. Only through embedding this hierarchy across the business can geotechnical contractors achieve the step change required to meet net zero.

May 1, 2022

By Harald Vogel, Johannes Lachenski, Friedemann Koetzel, Sebastian Schnell

In this paper, a digital subsoil approach, a work-in-progress, will be presented describing the transformation from a classical 2D to digital 3D thinking process in the design of geotechnical structures. Certain pitfalls as well as lessons learned are described, and the reader can understand that the digitalization process of the design of geotechnical structures is always a problem-focused approach by creating systems for certain processes rather than setting rules or regulations. Three project examples are presented. Two of the presented project examples feature a heterogeneous geology distribution and made it necessary for the design of the foundations to work with 3D subsoil and 3D calculation models. However, the digital 3D design process in the third project, an inner-city excavation pit, is driven by the complicated boundary conditions making it necessary to work in a parametric 3D design space. All projects have in common, that new processes had to be developed. The paper concludes with a flow chart describing the process of the elaborated digital subsoil approach.

May 1, 2022