Proceedings of the 5th International Conference on Transportation Geotechnics (ICTG) 2024, Volume 1

Table of Contents

1. Frontmatter

2. Use of Unmanned Aerial Vehicles (UAVs) for Transport Pavement Inspection

   Bertha Santos, Pedro Gavinhos, Pedro G. Almeida, Dayane Nery

   Abstract

   Technological evolution has allowed the use of unmanned aerial vehicles (UAVs) in an easier and more diversified way, creating opportunities for its application in various fields of engineering, namely in the inspection of transport infrastructures. The present study begins with the analysis of the main practices that resort to the use of UAVs, in order to frame its application in the field of transport pavement inspection. A review of studies and other available literature served as a starting point to define the methodology adopted for the development of the case study presented. The methodology includes the collection of images of a flexible road pavement section, its processing, and the creation of an orthoimage and a 3D model from which it was possible to identify and characterize the distresses present on the pavement surface. The main results obtained point to planimetric and altimetric deviations of less than 2 and 10 mm, respectively, for the images collected by the Mavic 2 Pro drone at 3 and 20 m high. With the collected data, it was also possible to calculate the global quality index PCI for the inspected pavement section. Under these conditions, it is possible to conclude that the accuracy is very good and suitable for the intended purpose, allowing fast data collection at low cost. This new technological approach supports infrastructure managers in the design of maintenance programs and in the scheduling of interventions, thus contributing to the increase of the durability and safety levels of the inspected pavements.

3. Integrity Testing of Diaphragm Walls by Thermal Methods

   Brent R. Robinson, Matthew Baudo, Richard C. L. Yu

   Abstract

   Distributed measurements of temperature in drilled or bored pile foundations to assess the integrity of the curing concrete have become increasingly common in the past decade. These methods have the advantage of detecting significant anomalies inside and outside of the reinforcing cage as the initial hydrating of the cement in the concrete generates heat. Conditional acceptance or further review of the foundation can be obtained within one to two days of casting. More recently, these techniques have been applied to diaphragm wall panels used in tunnels and other building construction. The expected trends in the temperature versus depth data are reviewed, indicating the consistency of measurements on the wall faces and cooler zones at the corner. An example showing the detection of local concrete cover changes and potential inclusions or non-uniformities at the bottom of the panels are also presented.

4. An Application of Geotechnical Instrumentation Permanently Embedded in Railway Track

   David Milne, Geoff Watson, William Powrie, Ben Lee

   Abstract

   Researchers and engineers rely on information and data to study, operate, maintain, and improve transportation infrastructure. Measurement provides quantitative information and evidence for these purposes. Sensors for measurement can be embedded into the track system at a fixed location or vehicle mounted. This paper describes the design, deployment, and operation of a permanent measurement system that uses sensors embedded in the trackbed on an operational railway in the United Kingdom to monitor track deflection, stiffness, and pressures at key trackbed interfaces. The measurement systems comprise a longitudinal array of accelerometers fixed to sleeper ends; dynamically sampled total pressure cells placed at the ballast-subgrade interface; and total pressure cells, piezometers, and accelerometers buried in the subgrade. Permanent, fixed sensors provide large volumes of detailed but highly localized information, while multichannel sensor arrays produce data that describes performance along the track. Methods for data reduction are proposed for the acceleration measurement system that allows spatial and seasonal variation to be visualized along the instrumented site for different train types. This approach enables comparison with track geometry data from rolling (on-train) measurements. Locally, buried instrumentation provides evidence for variation in load transfer to the subgrade both along the line and across individual sleepers; illustrates how interaction between wheelsets varies with depth and by vehicle type; and how the pore water responds to train loading. The application of measurement for monitoring purposes permits an analytical approach to data interpretation where monitoring parameters are similar to those used for design and simulation.

5. Transforming Construction Waste into Eco-Friendly Vegetated Embankment Slopes: A Path to Sustainable Infrastructure

   Trishia Liezl Dela Cruz, Ekaterina Kravchenko, Charles Wang Wai Ng

   Abstract

   Construction and demolition wastes (CDW) are being explored as a viable alternative material for geo-environmental applications, including embankment fill material for roads and railways. However, there are still limitations to CDW use, specifically on its environmental effect. Maintaining a well-balanced relationship between construction and the environment is crucial to avoid ecological problems. Hydrochar obtained through hydrothermal carbonization can adapt CDW for the growth of plants needed to stabilize CDW embankment slopes. Given the highly alkaline nature of CDW and its potential environmental impact, hydrochar presents a possible solution to improve the efficiency of CDW as an embankment material and plant medium. However, there is a lack of research to prove the feasibility of using hydrochar to fully utilize CDW in transportation engineering applications through greening. In this study, hydrochar was produced from peanut shell and wood biomass at 250 °C and 1 h of residence time. To assess the chemical and physical properties of hydrochar for CDW remediation, pH and electrical conductivity tests, proximate analysis, surface area and pore volume tests, and Fourier Transform Infrared Spectroscopy were conducted. Compaction tests were also conducted on the hydrochar-amended CDW. The acidic nature and porous structure of hydrochar have significant implications for positive improvement of CDW properties.

6. A Comparison Between Traditional and Satellite Monitoring by Means of Dinsar Technique Within the Framework of the Construction of Metro Line 1 in Naples

   Manuel De Luca, Gianpiero Russo, Marco Valerio Nicotera, Diego Di Martire, Ilaria Esposito

   Abstract

   The Naples Metro Line 1 is an important infrastructural work that extends for approximately 18 km, connecting 19 stations in the city. The project is developed in a particularly complex geological context, characterized mainly by soils and rocks of pyroclastic origin and marine sands. This article focuses on the monitoring of subsidence movements around the stations of Università and Toledo stations, as it is of particular geotechnical interest due to the dense urban and construction context surrounding it. Traditional monitoring operations carried out through optical leveling between 2002 and 2009, encompass both the underground stations and connecting tunnels. The aim of this study is to compare the data obtained through the remote sensing technique DInSAR (Differential Synthetic Aperture Radar Interferometry) using measurements from the ENVISAT (2002–2010) sensor, with the results of traditional monitoring. The data from the COSMO-SkyMed constellation, of the Italian Space Agency, are then analyzed to evaluate any posthumous movements that have occurred along the same section since 2010, therefore in the post-construction phases, in order to identify any critical issues that may require further investigation.

7. Deep Learning Approach for Automated Railroad Ballast Condition Evaluation

   Jiayi Luo, Kelin Ding, Issam I. A. Qamhia, John M. Hart, Erol Tutumluer

   Abstract

   Ballast has a significant impact on track performance, and the evaluation of ballast condition is crucial for safe railroad operations. This paper focuses on a Ballast Scanning Vehicle (BSV) recently developed for automating ballast inspection using a deep learning-based, computer vision approach. Traditional evaluation methods, e.g., visual inspection or ballast sampling followed by sieve analysis, are subjective and labor-intensive. Furthermore, ballast samples collected from a single location/depth may not be representative of accurately revealing variations of degradation and ballast condition along the track. In contrast, the BSV employs three image acquisition devices to continuously capture high-quality scans of ballast cut sections, enabling accurate and in-depth evaluation of continuous sections of the track. The deep-learning framework was trained to process acquired ballast scans, generating image-based metrics including percent degraded segments (PDS), fouling index (FI) estimates, and in-service ballast gradations. The accompanying user-friendly graphical interface integrates all data processing algorithms and provides comprehensive visualizations of results. Field data was collected using the BSV, from cut trenches opened using a ballast regulator, along the High Tonnage Loop (HTL) at the Transportation Technology Center (TTC) in the U.S. The FI and gradations from the BSV were compared to laboratory sieve analyses and Ground Penetrating Radar (GPR) data. Additional laboratory tests with various fouling conditions were conducted to validate the deep learning algorithms and clarify any differences between sieving results and algorithm estimates possibly attributed to sampling issues. This field deployment demonstrated that the BSV could accurately evaluate ballast conditions close to real time, thus making it a robust system for quantifying ballast degradation.

8. Smart Pebbles to Monitor Aggregate Response Under Repeated Loading

   Syed Faizan Husain, Mohammad Shoaib Abbas, Han Wang, Issam I. A. Qamhia, Erol Tutumluer, John Wallace, Matthew Hammond

   Abstract

   This study investigates aggregate particle movements under repeated loading in a controlled laboratory environment. Smart Pebbles, 3-D printed aggregate-shaped particles instrumented with gyroscopes and accelerometers, were used to capture particle movements in a geogrid-stabilized triaxial specimen subjected to repeated load pulsing. The study aims to understand the impact of geogrid stabilization on aggregate particle movements within an unbound base layer subjected to moving wheel loads, a critical determinant of layer stability. Two Smart Pebble sensors were placed at different depths in triaxial specimens. Each test configuration was designed to monitor and comparatively assess the aggregate movement in relation to its spatial position in the specimen. The results reveal a reduction in translational and rotational acceleration of the Smart Pebble where a geogrid is present, while the sensor placed near the top of the specimen experienced a higher translational acceleration. The Smart Pebble could thus be used as a tool to quantify the zone of influence of a geogrid and could be utilized for structural health monitoring of unbound granular layers in pavements.

9. Use of Bamboo Piles in Ground Improvement Design—Case Study

   Thayalan Nall, Jay Ameratunga, Andreas Putra

   Abstract

   A semi-rigid ground improvement method using bamboo poles is used in some countries in the Southeast Asian region, to improve land underlain by weak clays. It is a technology often used in projects in some areas of Indonesia where soft soils are common. Although this approach is adopted as a common ground improvement technique, the design is largely based on local experience. The semi-rigid inclusion consists of several individual bamboo poles bundled together as a cluster. In some projects a prefabricated vertical (wick) drain is also attached to the bamboo cluster to facilitate a shorter drainage path length. Following the installation of bamboo clusters, a bamboo raft is placed over them as a load transfer platform. This ground improvement technique is known as Bamboo Pile Raft System (BPRS). Although its performance under vertical loading has been found satisfactory in several projects, its performance under combined loading (vertical and horizontal) has not been understood well. The performance of a breakwater under combined loading was reviewed through numerical analysis to understand the behaviour of the BPRS ground improvement method. The results indicate that transient loading during construction and the depth of improvement with bamboo clusters in relation to weak clay thickness is critical. The results also show the increased strength gain due to pore pressure dissipation through wick drains incorporated in the bamboo clusters which helps improve the BPRS performance.

10. The Carbon Footprint of Vibratory and Impact Rolling: A Sustainable Option for Bulk Earthworks on Infrastructure Projects

    Derek Avalle, Burt Look, Brendan Scott

    Abstract

    Vibratory and impact rollers achieve deeper lift compaction than static rollers. Ground improvement with impact rollers occurs through rolling dynamic compaction, enabling compaction to significant depths, generally more than 1 m. This provides the opportunity to place thick layers, potentially with a larger maximum particle size than conventional smooth drum rollers, while achieving engineering standards of density and stiffness. The overall consequence of this is that the earthworks exercise becomes a far more sustainable activity. Deeper lift compaction beyond traditional thin compacted layers using conventional heavy vibratory rollers has been achievable for some time, but to lesser depths than is possible with impact rollers. The compaction of deeper lifts at faster operating speeds, albeit, typically with a greater number of passes, requires a fresh look at specifications for infrastructure earthworks. The paper explores the green credentials of deep lift compaction, by comparing earthworks plant, productivity and fuel usage for compaction using conventional circular drum rollers with thin layers, and deeper lift compaction using vibratory and polygonal impact rollers. Quality control to greater depths can be a limiting factor. Testing protocols often require modification to accommodate the changes in layer thicknesses and material specifications.

11. Design and Construction Monitoring of a Road Embankment and an Underpass Founded on Soils Susceptible to High Static Settlement and Liquefaction

    Raathiv Shanmuganathan, David Sullivan

    Abstract

    The Waikato Expressway is one of the New Zealand Transport Agency’s (NZTA), now Waka Kotahi, seven Roads of National Significance. Tetra Tech Coffey is part of the City Edge Alliance (CEA) engaged by Waka Kotahi to design and construct the Hamilton Section of the Waikato Expressway project. As part of the project, the CEA was required to design and construct an 8 m high embankment founded on soil consisting of highly compressible soft Peat, Clay, and liquefiable embedded Sand layers. Preloading the subsoil with a high surcharge was recommended to minimise the post-construction settlement at the expressway embankment and underpass concrete box structure at Powells Road. Contiguous flight Auger (CFA) lattice was utilised post-surcharge to improve the ground further at the underpass location. The CFA ground improvement was not utilised in the earthwork’s embankment portion on either side of the underpass to minimise the construction costs. Planning and designing a new 8 m high soil embankment close to a CFA soil improvement zone increased the need for accuracy in differential settlement and complexity of the work. Limited laboratory testing and underestimated compressible soil parameters caused delay in the settlement rate in the initial stage and additional surcharge was placed to speed up the consolidation period. Several settlement monitoring instruments were installed and several settlements back analysis methods using finite element modelling and empirical methods were used to observe the settlement rate and estimate the additional surcharge requirement. This paper presents the design and monitoring of an expressway embankment for static and dynamic loads, action taken to stabilise the surcharge slope failure and other difficulties faced during construction.

12. A Discussion on the Use of Geophysical Methods When Assessing Ground Conditions for Remediation Design of Road Embankment Failures

    Reagan Newton

    Abstract

    A common problem faced following a road embankment failure is undertaking site investigation, for remediation design, safely. Failure sites are often unstable and traditional methods of investigation (e.g., boreholes) pose a significant safety hazard to those undertaking the investigation and could induce further instabilities at the site. In addition to the hazards of the failure, road corridors often have to remain open to continue to provide vital transport connections for the continuation of freight movement, people movement, and emergency services (e.g., ambulance, fire and rescue) which adds further constraints when choosing site investigation methods. Geophysical techniques provide a potentially safer alternative to traditional boreholes when investigating failure sites with the ability to be flexible with the continuation of road traffic. This paper presents a discussion of the advantages and limitations of some of the available geophysical techniques that could be utilized when conducting geotechnical site investigations at road embankment failures. A recent case study of a road embankment failure is also presented where the use of geophysical methods was utilized due to borehole drilling being deemed unsafe at the failure site.

13. A Case Study on the Bearing Capacity of Large Diameter Bored Piles Plugged in Weathered Limestone for Cable-Stayed Bridge

    Do Huu Dao, Pham Van Ngoc, Huynh Phuong Nam, Ho Dac Khanh Minh

    Abstract

    For bridge projects, load testing for large-diameter bored piles in the middle of a river is a challenge for traditional static load testing methods. The Bi-directional Static Axial Compressive Load—BSACL (ASTM D8169-18) solution is a reasonable method with the advantages of not using weight load and faster progress. This article presents the results of BSACL for a 1500 mm diameter bored pile, 45.5 m long, with the pile tip embedded in a weathered limestone layer. This is a case study of the Hieu River cable-stayed bridge in the center of Vietnam with a 200 m length span. The maximum load reached 17,250 kN applied through a Load Box placed at a depth of −37.4 m, with a movement of the Load Box approximately 11.9 mm upward, 9.8 mm downward, and 6.3 mm at the pile head. The side resistance in the slightly weathered limestone layer (RQD = 30%) achieved 350 kPa, and in the highly weathered limestone layer reached 175 kPa (RQD = 0%). The side resistance of the soil layers above the Load Box is also analyzed through strain gages simultaneously. The research results could help engineers to understand the load distribution along the bored piles.

14. Preloading as a Sustainable Ground Improvement Solution for Road Infrastructure

    Alvin Chen, Evan Kailis, Sergei Terzaghi

    Abstract

    Construction of infrastructure over soft soils presents significant challenges for sustainable foundation solutions due to low bearing capacity, high compressibility, ongoing long-term creep and onerous design performance criteria. The commonly adopted solution to these challenges is to construct a rigid structure which is often carbon intensive, costly and does not necessarily circumvent all differential settlement issues. This paper presents a case study of the preloading treatment design of a road embankment at a site in Wentworth Point, NSW, underlain by soft reclaimed and alluvial sediments between 12–20 m deep. Ground improvement through preloading and surcharging was proposed for the new road infrastructure servicing the development buildings, in lieu of piled foundations or rigid inclusions adopted for neighbouring developments. By using clusters of investigation (boreholes, CPT, sDMT) with laboratory testing, detailed ground profile interpretation was possible to develop Finite Element models to predict soft soil creep model under proposed treatments. During the ground treatment period, the contractor and design team adopted an observational method in determining the treatment period, following a set monitoring regime and a response plan. This case study includes a discussion on the considerations and lessons learned in pursuing a more sustainable foundation solution in soft soil including monitored impacts of Prefabricated Vertical Drain Installation and the value of plotting data differently to see what is happening through a different lens.

15. Improving Low-Lying Acidic Floodplains for Infrastructure Development

    Subhani Medawela, Buddhima Indraratna

    Abstract

    In coastal Australia, shallow pyrite deposits (FeS₂) in low-lying terrains oxidise to produce sulfuric acid that pollutes the soil and groundwater, thus adversely affecting the environment, coastal development, fisheries, and agricultural development. Permeable Reactive Barrier (PRB), an underground granular filter, is a practical engineering technique that neutralises groundwater acidity. Two pilot-scale PRBs were installed in the lower Shoalhaven floodplain, NSW, Australia, to treat the acidic water using alkaline aggregates as the reactive material. However, during the treatment of contaminated groundwater, the entrapment of biomass generated by bacteria and secondary mineral precipitates within the granular matrix reduces the hydraulic conductivity and porosity of the PRB and affects its longevity. Real-time monitoring data of the field PRB and its clogging patterns along the centreline of the PRB are discussed in this paper. Clogging and armouring were non-homogeneous along the flow path, and the acid neutralisation capacity at the inlet of the PRB decreased by 31% in 15 years due to clogging, but only a 6% reduction was observed at the outlet.

16. Semi-analytical Wavefield Modelling for Pavement

    Mrinal Bhaumik, Tarun Naskar

    Abstract

    This study presents an efficient semi-analytical wavefield modeling approach to generate surface wave dispersion spectrum for pavement-type structures. The method addresses the challenges posed by complex wave propagation through inversely dispersive medium, where the observed velocity spectrum often presents numerous mode branches. It computes theoretical dispersion curves, including real and leaky modes with complex wavenumbers by employing an eigenvalue-based higher-order thin layer method. Subsequently, the frequency domain dynamic surface responses are obtained to simulate in-situ pavement testing. The proposed approach is implemented on two pavement profiles: one representing an asphalt pavement model and the other a rigid concrete pavement model. The dispersion spectrum for the asphalt pavement has been validated against published numerical simulation. The study highlights that the fundamental antisymmetric mode of Lamb wave generated by the top layer dominates the wavefield. The overall dispersion trend can be utilized to estimate the properties of the top stiff layer. The low-frequency dispersion spectrum shows multiple modes corresponding to the base embedded layers underneath the surface layer. With the proposed wavefield modelling approach, the entire dispersion spectrum can be inverted to obtain the properties of the base course layers, eliminating the challenges to select specific modes.

17. Predicting the Shear Strength of Granular Waste Materials Using Machine Learning

    Haydn Hunt, Buddhima Indraratna, Yujie Qi

    Abstract

    Knowing the shear strength of soil is imperative for geotechnical design as shear failure, combined with excessive deformations, is the predominant failure mechanism within a loading environment. However, determining the shear strength in the laboratory is often laborious and hence costly. Moreover, a granular material’s behavior is complex which can compromise the accuracy and robustness of predictive models developed through traditional methods. This is exacerbated when considering non-traditional waste materials such as steel furnace slag, coal wash, and scrap rubber due to their increased nonlinearity and variability. Consequently, previous relationships and models proposed are often self-contained and break down when extrapolated beyond specific loading conditions or material types. In this study, predictive models for the peak friction angle (ϕ^′_peak) of various granular mixtures (waste and non-waste) were developed using two nonlinear machine learning (ML) techniques, namely, artificial neural network (ANN) and second-order multivariable regression (MR). Five key parameters were chosen to represent the mixture type (rubber content, median particle size), its physical properties (initial void ratio, dry unit weight), and the loading condition (effective confining pressure) using 154 consolidated drained triaxial test data samples. Although MR performed satisfactorily on both the original and secondary datasets, ANN combined with Bayesian regularisation was superior with R² of 0.96 and 0.82 for both phases, respectively. Hence, ANN is an attractive modelling technique as it is capable of capturing nonlinear relationships for various granular mixtures (i.e., waste and non-waste, with and without rubber) to predict shear strength without the need for laboratory testing.

18. Bayesian Back Analysis for Settlement Prediction of Embankments Built on Soft Soils Incorporating Monitoring Data—A Case Study

    Merrick Jones, Shan Huang, Jinsong Huang

    Abstract

    A novel method for back analysis was used for an embankment over deep soft soil along a major highway upgrade between Woolgoolga and Ballina, NSW. Bayesian back analysis was undertaken using monitored settlement data. The key parameters of interest were the compression ratio, recompression ratio, creep strain rate and coefficient of vertical and horizontal consolidation. Posterior distributions were sampled using a multi-chain Monte Carlo algorithm through a likelihood function to estimate the updated model parameters and subsequent settlement prediction. The simplified geotechnical model, incorporating parameter ratios, can be shown to reduce the amount of computational time required. The predictions were shown to converge to the field measurements regardless of some assumptions made about measurement error and aided in providing a more consistent prediction based on the available data. The intent of the study was to demonstrate that key geotechnical parameters can be updated, and settlement predictions revised and verified from limited site investigation data using Bayesian back analysis incorporating monitored surface settlement data.