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2025 | Buch

Proceedings of the 5th International Conference on Transportation Geotechnics (ICTG) 2024, Volume 3

Integrating Mega Project Planning, Airfield Behavior, and Rail Transition Zones

herausgegeben von: Cholachat Rujikiatkamjorn, Jianfeng Xue, Buddhima Indraratna

Verlag: Springer Nature Singapore

Buchreihe : Lecture Notes in Civil Engineering

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SUCHEN

Über dieses Buch

This book presents select proceedings of the 5th International Conference on Transportation Geotechnics (ICTG 2024). It includes papers on ground improvement methodologies, dynamics of transportation infrastructure, and geotechnical intricacies of mega projects. It covers topics such as underground transportation systems and heights of airfields and pavements. This book discusses diverse thematic landscapes, offering profound explorations into sensor technologies, data analytics, and machine learning applications. The publication highlights advanced practices, latest developments, and efforts to foster collaboration, innovation, and sustainable solutions for transportation infrastructure worldwide. The book can be a valuable reference for researchers and professionals interested in transportation geotechnics.

Inhaltsverzeichnis

Frontmatter
Bio-modification of Concrete for Pavements

Lean concrete has been used for pavements or footpaths. However, the production of cement generates CO2, and thus to achieve green construction, we need to use less cement or substitute materials for cement. One method to reduce cement usage is to modify the aggregates used for lean concrete so that the bonding between cement and aggregates can be stronger and thus less cement can be used. A Microbial Induced Carbonate Precipitation (MICP) process has been adopted to treat aggregates used for lean concrete. The study shows that the aggregates modified by a MICP treatment could increase the cubic strength by 21.4% at 28 days of curing. Further studies were also carried out to use sea sand rather than river sand for lean concrete. The results also indicate that the strength of lean concrete made with MICP-treated sea sand was also increased by 24.8% at 28 days of curing when compared to untreated lean concrete made with river sand. This study is meaningful as the supply of river sand is much less than sea sand. On the other hand, sea sand is considered not suitable for lean concrete as chloride in sea sand will weaken the strength of lean concrete. This study appears to have established a method for sea sand to be used for lean concrete for pavements.

Samuel Ng, Jian Chu
Finite Element Analysis on the Distribution of Stress Through Layered Soils

Evaluation of stress distribution through soil strata is one of the fundamentals of geotechnical analysis. Vertical stress is attributed to the loading intensity and geostatic stress. Even though many analytical methods have been developed idealizing the soil as a homogeneous, isotropic, and elastic material, the soil consists of layers of different characteristics in reality. In this study, stress distribution under a strip footing through a two-layered system consisting of purely sandy and purely clayey soils where the sand at the top was analyzed with the finite element method using Plaxis 2D geotechnical software. The Mohr–Coulomb model was used to feed the characteristics of the soils to the computer software. Different test cases were simulated by changing the soil strength parameters; friction angle of sandy soils, undrained cohesion of clayey soils, and the thickness of two layers for selected soil types, while the total depth of the soil system was 8 m. The numerical results were compared with Boussinesq’s solutions which are linear elastic solutions. It shows that stress at a selected point is small when the soils are loose and soft compared to the soils which are dense and stiff. The lower the thickness of the sand layer higher the stress at a selected point. Vertical stress values of Boussinesq’s solutions agree with the finite element analysis values when moving away from the footing both in horizontal and vertical directions.

Isuri Wijayarathne, Nalin de Silva
Balanced Mix Design in Kansas

AASHTO PP 105-20 defines Balanced Mix Design (BMD) as “an asphalt mix design using performance tests on appropriately conditioned specimens that address multiple modes of distress considering mix aging, traffic, climate, and location within the pavement structure.” The traditional Superpave mix design process only considered volumetric properties and mainly focused on rutting resistance. However, the effect of recycled materials, such as Reclaimed Asphalt Pavement (RAP), Reclaimed Asphalt Shingles (RAS), etc., are not considered, and the performance properties of these mixtures cannot be captured in the Superpave system. BMD could provide a performance-optimization process for asphalt mixtures. This new approach involves performance testing, including cracking and rutting tests. Despite promotion from various entities, Kansas is cautiously approaching this new development of HMA mixture design. In this study, the cracking test, IDEAL-CT, was conducted on several Kansas HMA mixtures containing recycled materials, and the results were generated to assess the applications of BMD in Kansas. This paper describes this assessment.

Ya Gao, Mustaque Hossain, Blair Heptig, Steven Houser
A Simple and Economical Procedure for the Design of Capping Layers in Earthworks

In French road structure design, the capping layer is by default an essential element of it as it has to fulfil many functions. From an economical point of view, it is important to optimise its thickness as it is typically either made of imported granular or site-won stabilised materials. In 1983, a relationship was established by the main author to determine the thickness of granular capping layers covering all situations in terms of stiffness characteristics (subgrade, formation level and granular material). To date, in the case of stabilised capping layers, French engineers have simply been relying on well-established empirical tables published in the ‘GTS’ national notes for guidance. The major drawback of these tables is that only a few scenarios are covered. This article describes these methods of determining the thickness capping layers and completes it with a new approach in the case of stabilised materials so that all situations can be considered.

J. C. Gress, M. Ferreira, L. Beeuwsaert
Impact of Spatial Variability of Material Properties Compacted Geomaterials on Acceptance

Proper compaction of unbound materials in the pavement structure is a key component towards achieving the desired performance of a well-designed pavement. Transportation agencies commonly use the nuclear density gauge as a part of their quality management program to ensure the desired compaction density is achieved. Because the mechanistic-empirical pavement structural design process makes use of modulus to characterize geomaterials, transportation agencies are seeking to transition to modulus-based methods for quality management. This paper presents the findings of a comprehensive study aimed at understanding the impact of in situ variability in stiffness, moisture content, and density of compacted geomaterials on construction quality acceptance. To conduct this study, a dataset was compiled from test sections selected from various pavement construction sites throughout the United States. A grid pattern of spot test locations was established along the test section where modulus-based testing using lightweight deflectometer alongside moisture and density measurements was systematically conducted. The study revealed instances where sites that met density requirements failed to meet acceptance when using a modulus criterion. Thus, achieving density is necessary but not sufficient, as the density and modulus are not directly related.

Cesar Tirado, Soheil Nazarian, Navneet Garg
Laboratory Testing to Design an Asphalt-Treated Permeable Base for the Federal Highway Administration’s Pavement Test Facility

The Federal Highway Administration reconstructed a new Pavement Test Facility (PTF) to perform accelerated testing on various pavement structures. Three of the eleven lanes were designed with an asphalt-treated permeable base (ATPB) to evaluate its impact on pavement response and performance. ATPBs are created by mixing an open-graded aggregate with a small percentage of asphalt binder; however, the job mix formula (JMF) and the compacted density of the mix all influence the stiffness, strength, and permeability of the resulting ATPB. To develop an appropriate JMF for the PTF, various unbound and ATPB specimens were prepared using three different locally sourced open-graded aggregates with 0 to 4% asphalt binder. Asphalt permeameter test specimens, 150 mm in diameter and 116 mm in height, were prepared using a Superpave gyratory compactor which also determines the minimum void ratio and the maximum density of the mix. The stiffness and strength of the ATPB specimens were measured by performing resilient modulus and quick shear tests on 150 mm by 300 mm compacted specimens. The stripping resistance of select ATPB specimens was evaluated by conducting tensile strength ratio tests. The findings showed that the asphalt binder content had a negative relationship with permeability and air voids but a positive relationship with stiffness. The binder grade and specimen gradation had a significant impact on moisture susceptibility. The results informed the selection of the ATBP JMF for the PTF. This paper provides an overview of the PTF design requirements and the ATPB experimental approach with the results.

Ismaail Ghaaowd, Michael Adams, Jennifer Nicks, Scott Parobeck
Investigation of Rut Formation in Asphalt Concrete Pavement

In the article, in field (on the bus lane of a city road) using modeling and traffic flow analysis methods, the rut formation on an asphalt concrete pavement is studied. The maximum total rut depth on the road section under consideration reaches 92 mm; 5% of measured rut depths exceed 35 mm; 75% of them are more than the permissible value. Almost 1100 trolleybuses and buses pass along the bus lane of the road per day, the relative rutting effect of which is from 3.04 to 6.59; their permissible number of passages ranges from 37,823 to 82,069. The pavement structure on the experimental section with a total thickness of 50 cm is too weak for the actual traffic flow, which was the main reason for the premature destruction of the road due to unacceptable track sizes on the asphalt concrete surface.

Bagdat Teltayev, Alibay Iskakbayev, Arystan Massanov, Yerbol Aitbayev, Azamat Zhaisanbayev
Evaluating the Effects of Particle Size Distribution on the Hydraulic Capabilities of the Granular Subbase Layers

The hydraulic performance of the flexible pavement is defined by the particle size distribution (PSD), thickness, and degree of compaction of the Granular Subbase (GSB) layer. Transportation agencies like the Indian Roads Congress (IRC) and the American Association of State Highway and Transportation Officials (AASHTO) insist that the GSB layer intends to have a minimum in-plane permeability of 300 m/day to attain optimal performance. In addition, the designers should consider the concept of internal stability of granular filters so that a stable gradation is ensured even under the impact of external factors such as seepage and vibrations. In this study, newly proposed GSB gradations were evaluated for their in-plane permeability characteristics and internal stability, and the results were compared with those of the existing GSB gradations. The in-plane permeability characteristics are evaluated experimentally through a large-scale permeameter under different hydraulic gradients. The internal stability of the GSB gradations is evaluated analytically using the internal stability index. The comprehensive test results indicated that the effects of PSD and hydraulic gradients highly influenced the in-plane permeability of the GSB. The open-graded GSB materials are intended to have a higher rate of permeability and a lower internal stability index than the dense-graded GSB materials.

Abishek R R, Sireesh Saride
Geotechnical and Geophysical Characterization of Delhi Metro Tunnel Alignment: Section Between RK Ashram and Nabi Karim

To evaluate the stratigraphy along an underground tunnel alignment between RK Ashram and Nabi Karim for the Delhi Metro, a detailed study was performed. This included geotechnical investigation by drilling boreholes, performing in situ permeability tests and dilatometer tests together with geophysical surveys such as seismic refraction tests, electrical resistivity tomography, and cross-hole seismic tests. Using a combination of geotechnical and geophysical testing, a reliable geotechnical-cum-geophysical model was developed to characterize the ground profile and trend of rock along the metro alignment.

Ravi Sundaram, Sorabh Gupta, Sanjay Gupta, Saurabh Sharma
Foam Penetration Behavior in EPB Shield Tunneling: Insights from Model Experiments

Soil conditioning is crucial in maintaining stability during earth pressure balance (EPB) shield tunneling. Understanding the properties of the soil conditioner and its impact on soil is essential for ensuring the safety of the tunneling. This study focuses on investigating the penetration behavior of foam, a commonly used soil conditioner, in saturated sand. Experiments were conducted using a sand column device to simulate the foam penetration process in different sand beds. The experimental results reveal that foam penetration in the sand forms two linear pore pressure drop regions with different gradients, with the foam penetration area occupying the majority of the pore pressure. The foam penetration also introduces a flow velocity reduction in the sand column, resulting in blocking. Furthermore, a notable correlation emerged between the foam penetration velocity and the hydraulic gradient, akin to Darcy's law but with a different expression equation. The findings contribute to enhancing our understanding of soil conditioning in EPB shield tunneling and support the design of safer and more efficient tunneling processes.

He Huang, Wan-Huan Zhou
Geotechnical Conditions for Construction of Savski Trg Metro Station as a Part of the Belgrade Metro Line One

In order to solve serious traffic congestion in Belgrade, a number of studies regarding the Belgrade Metro construction have been carried out since 1973. However, only in 2019, the routes of the future metro lines 1 and 2 were defined as a part of the General Metro Construction Project. The lines are designed to intersect at the location of Sava Square, where an interchange metro station will be built. It represents a complex geotechnical structure consisting of three different parts: a part of the metro station for line 1, a part of the metro station for line 2, and a common part for both metro lines. Due to the complexity of construction and different depths of the diaphragm walls, deeper than 40 m on the part of metro line 2, phased construction is planned. In this regard, determination of geotechnical modeling for each part separately as well as geotechnical design are presented including the analysis of phased methods of excavation, influence of pore and effective stresses on the stability of the diaphragm wall, lateral and vertical displacements as well as the interaction between diaphragm walls and reinforced concrete slabs.

Nemanja Stanic, Dragoslav Rakic, Josip Isek, Slavoljub Simic
Geotechnical Considerations in Buried Pipeline Design Crossing Transport Corridors

The Australian standard (AS2566) for buried pipes provides a design methodology and recommends ground parameters for design. The values referred to as soil modulus equate an embedment modulus (which is a soil–pipe modulus reaction) and a native soil modulus. For low-height fills and small-diameter pipes, the equated native soil modulus value used does not significantly affect a calculated deflection. As live load, depth or pipe diameter increases, these inconsistencies become apparent. Where pipeline crossings at road or rail corridors occur, the limitations of AS2566 become apparent. When finite element method (FEM) is used to examine soil–pipe interactions, input soil parameter values different from those provided in AS2566 must then be used. Case studies of a finite element analysis for a large-diameter buried pipe subject to traffic loading are compared with the AS2566 design procedure. The limitations of equations used in calculating the pipe deflection are shown.

Burt Look, Roozbeh Mirjalili
Analyses of Rules for Distinctions Between Shallow and Deep Tunnels

Distinctions between shallow and deep tunnels are conducive to pursuing suitable strategies for tunneling. This paper first examines the current practices on the rules for distinctions between shallow and deep tunnels and then conducts both theoretical and numerical analyses of these rules for tunneling in homogeneous ground, to shed some observations on the relevant issues: (1) The distinction depth increases when the prescribed ground pressure ratio decreases and vice versa. (2) For a specific ground pressure ratio value, the worse the rock stability, the larger the distinction depth. (3) The distinction depths calculated by using the Terzaghi formula are more conservative than the China design code. (4) The distinction depths by using the Protodyakonov formula are even more conservative. (5) The distinction depths by using the Terzaghi formula can be verified by finite element simulations of tunnel excavations.

Yanyong Xiang, Hasan M. D. Shahad
Rheological Consolidation Characteristics of Soil Around Tunnel Under Exacerbated Leakage Conditions Based on Boltzmann Function

The Boltzmann growth function is introduced to study the soil consolidation behavior caused by shield construction disturbance when the lining permeability deteriorates, and the general Voigt model is used to characterize the rheological properties of saturated soft soil. Based on the Terzaghi–Rendulic theory, the governing equations for the consolidation of saturated soft soil around the tunnel were established. The shield tunnel project in Kunming’s peat soft soil area is taken as an example to analyze the consolidation property. The results show the speed and curve shape of the excess pore water pressure dissipation are closely related to the leakage exacerbation mode of the lining. Increasing the number of Kelvin bodies results in slower dissipation of pore pressure, resulting in incomplete dissipation and pronounced step-like behavior.

Anfeng Hu, Senlin Xie, Zhirong Xiao
Simulation Study on the Construction Parameters of Ultra-Deep Diaphragm Wall of High Pressurized Water Sand Layer

When a large deep foundation pit is constructed in a typical complex stratum with high pressurized water sand layer, the displacement response of the diaphragm wall will develop gradually and dynamically with the active loss or passive extrusion of the stratum, which will put the enclosure structure in a dangerous state once it exceeds the limit value required by the current standard. Reasonable determination of the important construction parameters of diaphragm wall under such stratigraphic conditions is essential to the fine control of deep foundation pit enclosure structure construction, and is also a prerequisite to ensure the safety and reliability of deep foundation pits and the surrounding environment. This paper uses numerical simulation to carry out orthogonal experiments, selects the elastic modulus of diaphragm wall, diaphragm wall thickness, support stiffness and support cross-sectional area as experimental factors, takes the horizontal displacement of the diaphragm wall as the safety evaluation index, and the reliability of the model was verified through on-site testing. The innovative construction parameter selection method proposed in this paper will provide a basis for the design of deep foundation pit envelope structure, and provide a reference for the design of intelligent foundation pit.

Meng Li, Yao Shan, Zhining Chen, Peng Dai
Observations of Tunnelling Effects on a Large Diameter Jointed Steel Pipe in Rock

This paper presents the monitoring results of a 2.5 m diameter pressurized water supply tunnel (Water Tunnel) with segmental steel liners, subjected to ground movements caused by the excavation of a twin road tunnels crossing above the Water Tunnel with an excavation clearance of 7.5 m excavation. Discussion is provided on the progression of the external monitoring results for ground movements based on extensometers, inclinometers and piezometers, as well as internal monitoring results for the Pressure Tunnel based on multi-directional strain gauges.

Ashok Peiris, Audrey Poon, Kim Chan
Coupled Hydro-Thermal Response of Unsaturated Soils Under Non-isothermal Conditions

Energy piles are often partly or fully embedded in unsaturated soils. Design of energy piles assuming the surrounding soil is dry or fully saturated may lead to underestimation or overestimation of their performance, in terms of heat exchange efficiency as well as structural stability. To achieve a safe and efficient design of energy piles in unsaturated soils, it is crucial to quantify the coupled hydro-thermal (HT) processes involved in unsaturated soils subjected to non-isothermal conditions. Studies focusing fundamentally on the critical TH multiphysical processes surrounding energy piles are scarce, especially for unsaturated soils. Much of the literature on energy piles in unsaturated soils employ simplified conduction–convection heat transfer in porous media using the saturation-dependent thermal conductivity for their simulations while avoiding detailed mass and heat transfer and without any emphasis on vapor transport and latent heat transfer. This study discusses the coupled multiphysics processes in unsaturated soils with careful attention on the effect of vapor transport and latent heat transfer. Overall, the study proposes a numerical modeling scheme for unsaturated soils under non-isothermal conditions and provides a detailed analysis of the heat and moisture migration in unsaturated coarse sand.

Arvind Kumar, Asal Bidarmaghz, Arman Khoshghalb
A New Approach to Design of Ground Anchors in Rock with Due Consideration of Swelling Effects

It was found that the bond strength of ground anchors in weak Bringelly Shale was reduced resulting from the swelling effects during the drilling, clearing and washing process prior to grouting. This paper has proposed an approach on how the potential radial plastic displacement can be evaluated using an available empirical solution, and the swelling effect by means of numerical modelling during the ground installation process. It was found that the grout and rock interface is heavily influenced by the potential plastic displacement due to swelling. The conventional relationship of the ultimate bond strength of shale rock and the unconfined compression strength (UCS) has been reviewed for non-swelling rocks. A correlation relationship of bond strength equal to 0.11UCS when UCS <= 4 MPa and 0.14ULS for UCS > 4 MPa has been recommended for Bringelly Shale after the field pull-out testing and acceptance testing of many anchors in Bringelly Shale on the Sydney Metro—Western Sydney Airport, Station Boxes and Tunnelling project (WSA-SBT). This correlation could be used to forecast ground anchors in Bringelly Shale with swelling potential in the future.

Q. J. Yang, B. Xu
Automatic Calibration of Tunnel Volume Loss Using Leapfrog and the Limaniv Method

In increasingly congested cities, tunnels are being used for new transportation routes. It is important to be able to predict the ground movement resulting from tunnel excavation, in order to manage its impact on existing infrastructure. This paper describes a procedure for calibrating settlement trough parameters automatically, using the Limaniv method, in combination with Leapfrog models and Python scripting. This method predicts surface settlement, due to elastic squeezing of an excavated tunnel, due to the weight above that tunnel. This process allows parameters to vary continuously along the tunnel, providing a more accurate settlement prediction, and removing the need to apply overall highly conservative values. A weighting function, derived and presented in this paper, is used to obtain a single equivalent Young’s modulus value from multi-layered ground conditions. The code is implemented as a plugin to the Geographical Information Systems program, QGIS, and an example is given with a Leapfrog model of a location in Sydney, Australia. Settlement predictions from this approach are validated against numerical modeling.

Michael P. Crisp, Noman Farooq, Roshan Nair
Support of 30-m-Deep Excavation for TBM Launch and Future Underground Station of Sydney Metro West

The paper describes the design and construction of an anchored secant pile wall used to support the deep excavation which enabled the launch of two tunnel boring machines (TBM) for the Sydney Metro West Project near White Bay on Sydney Harbour. Bored piling with segmental casing as well as continuous flight auger (CFA) drilling techniques were used effectively to construct a 10~25-m-deep secant pile wall. The wall was required to temporarily support a 30-m-deep excavation in the geotechnically challenging White Bay Alluvium and Paleochannel sediments underlaid by the Sydney Hawkesbury Sandstone. The sandstone surfaces on the east end, and at the west end diving to a maximum depth of 22 m resulting in a unique challenge. Parts of the Great Sydney Dyke also intersected the excavation box. Two different shoring types (diaphragm walls and secant pile walls) were considered. Case histories and lessons learned from similarly deep excavations nearby along the Sydney Harbour were investigated to inform the concept design. Secant pile walls were selected due to several key reasons detailed in this paper. The key advantages of secant piles were de-risking against geological hazards, as well as benefits for the overall construction programme (TBM launch) when compared against other techniques.

Bora Okumusoglu, Matthew Sentry
Three-Dimensional Modelling of Twin Tunnelling with Different Skew Angles in Two-Layered Soils

Research has been carried out to study the effects of new tunnelling on an existing adjacent tunnel to ensure the safety and serviceability of tunnels. Prior studies on twin-tunnel interaction have mostly centred on simplifying perpendicularly crossing tunnelling in a single-layered soil stratum. New tunnel excavation beneath an existing tunnel at different skew angles in two-layered strata can lead to different patterns of stress redistribution and adverse impacts on the existing tunnel. In this paper, results of three-dimensional centrifuge and numerical modelling carried out to study the twin-tunnel interaction with varying advancing orientations and layered soils will be reported. The influence of new tunnel excavation on an existing tunnel was simulated in-flight by controlling both the tunnel weight and volume losses. An advanced hypoplastic constitutive model that can capture stress-, path-, and strain-dependency of soil behaviour is utilised for numerical back-analyses and parametric studies. Cases investigated include twin-tunnel interaction at three different skew angles (30°, 60°, 90°) in a uniform sand layer and at skew angle of 90° in two-layered sand with different relative densities and thicknesses. Distinct load redistribution patterns will be presented to explain deformation mechanisms of the existing tunnel at different tunnel advancing skew angles to highlight the effects of tunnelling orientation. The results of perpendicularly crossing tunnelling in two-layered sand will also be reported and compared to reveal the influence of layered soil. The findings and new insights can help engineers better estimate advancing tunnelling effects on existing tunnels and enhance the safety of tunnel construction.

P. Y. Zhu, Annie Y. Y. Wong, Aaron D. F. Buenaventura, Charles W. W. Ng
Design of a Temporary Retention System to Support Shaft Excavation for a Sydney Metro Project

As part of the Sydney Metro–Western Sydney Airport, Station Boxes and Tunnelling project, there was a need to excavate a circular shaft with a depth of 22 m and a diameter of 29 m. Notably, this shaft also incorporated a rock bench at its base to facilitate construction of four tunnel portals. A temporary retention system to support the shaft excavation comprised (a) Secant piles within the upper 11 m of the shaft. The secant piles were supported with a capping beam at the top and a ring beam at the bottom, (b) Eight piles situated on the sides of the tunnels, extending below the final excavation level to offer additional support to the retention system during tunnelling activities, and (c) Utilization of pattern rock bolts and shotcrete to stabilize the rock between the toe of secant piles and the final excavation level. To enhance stability of the rock bench and facilitate the breakthroughs of tunnel boring machines (TBMs), a pre-support system comprising spiling bar tubes and a shotcrete collar was employed. In the design of the retention system, various aspects were carefully considered, including loadings from ground, groundwater, and swelling rock, and interfacing with tunnels entering and exiting the shaft. This paper details the components of the retention system employed during shaft excavation and TBM arrival and relaunching activities. It outlines the design process involving finite element analyses to assess structural actions acting on the retention system elements. Finally, the paper discusses the instrumentation and monitoring program implemented to confirm the stability of the system throughout construction.

Theva Muttuvel, Sam Doan, David Malorey, Bonar Bucalina
Surface Settlement Induced by Urban Tunnelling—a Case Study of Mumbai Metro

Mumbai is an elongated island city and spreading towards northern side as the southern side is sea face. Mumbai Metro Line 3 (MML-3) project corridor from Colaba to Seepz, is fully underground metro of a total length 33.5 km twin tunnel. In this project, 17 nos. of TBMs deployed to construct the tunnel. The tunnel is excavated through Basalt underlying filled up material and soil strata (sandy and clayey). A systematic instrument arrays are installed along the tunnel alignment to monitoring at the ground, on the ground and in the tunnel, existing buildings along the tunnel alignment in the influence zone (both side of tunnel alignment) as per monitoring scheme. Monitoring of instruments was done as per the frequency required for tunnelling activities based on the excavation stages and to acquire the recorded data. Based on the monitoring data and their interpretation, design modification has been done to achieve safe tunnelling which is the first and foremost requirement in urban tunnelling. This paper highlights the surface settlement at the ground surface and in the tunnel excavated zone due to tunnelling.

A. Shesh Mani Sonkar, B. Alvaro Casasus
Estimation of Ground Surface Settlement in Pipe Box Tunneling

Pipe box tunnel (PBT) is a trenchless construction technique trending in a situation where the conventional open-cut-and-cover method is not feasible due to the presence of critical above-ground structures or the necessity to maintain the functionality of the main roads. Limited studies or methods exists for estimating the maximum ground surface settlement in the construction of pipe box tunnels, especially when compared to conventional bored tunnelling. This study utilises finite element analyses to investigate the impact of volume loss and cover depth on ground surface settlement in pipe box tunnelling. A chart was developed for the initial estimation of maximum ground surface settlement in pipe box tunnelling projects.

E. Woon
Construction of Underground Roads and Tunnels Beneath Sensitive Infrastructures in Singapore

Construction of underground roads, Mass Rapid Transit (MRT) tunnels and pedestrian underpasses within a built-up matrix of roads and infrastructure is becoming a common requirement in a city state like Singapore. Some of these underground structures tend to pass below busy roads, vehicular bridges and station boxes. Construction of these underground structures could possibly be disastrous if displacement and stresses within the system are not understood and controlled. This is especially true if the soil conditions are varied and weak. One of the more common means of carrying out these construction systems is by Pipe Box Tunnels (PBT) which consists of steel pipes arranged in a box form and internally supported by steel frames. This paper will discuss two different scenarios of the use of the PBT system detailing the design concepts, concerns and solutions. Details will be provided regarding the instrumentation and readings. The design predictions will also be discussed to show differences that occur.

How Yen Pan, I. Yogarajah, T. G. Ng, S. C. Teo, J. L. Xie
Reflections on a Flawed Planning Process for the Western Harbour Tunnel, Sydney

The paper is based on three report submissions made by the author to the NSW State Government Parliamentary Inquiry in 2021 into the Sydney Western Harbour Tunnel (WHT) and Beaches Link Tunnel (BLT) URL (Inquiry into impact of the Western Harbour Tunnel and Beaches Link–Sub 437 (2021) [1]; Inquiry into impact of the Western Harbour Tunnel and Beaches Link–Sub 437a (2021) [2]; Inquiry into impact of the Western Harbour Tunnel and Beaches Link–Sub 437b (2021) [3]). The WHT includes twin 16-m diameter TBM bored tunnels under Sydney Harbour as opposed to the original immersed tube proposal. The BLT was politically pushed, had initially been delayed but has now recently been cancelled with the change in state government in 2023. No Business Case for the BLT bored tunnel was publicly available. Major construction works are currently well advanced in and adjacent to the Warringah Expressway in North Sydney. The author’s submission proposed an extension of the WHT to go under North Sydney and beyond Chatswood (extending the WHT tunnel by at least 5km north, following the Pacific Highway corridor) and for a new 7km long east–west tunnel from the Roseville Bridge, Forestville to Macquarie Park passing under Chatswood, to replace the BLT. As part of this proposal a major underground interchange, conceptually similar, but less complex than the Westconnex Rozelle Interchange on the south side of the harbour, would be constructed under Chatswood. It is acknowledged that the financial viability of Westconnex depends on the completion of the WHT. Some concept images of the proposals are included together with the advantages over the current WHT alignment and the now cancelled BLT project. Other planning issues include a lack of redundancy in the road network leading to accident-related significant traffic delays, ventilation stack air pollution issues, community impacts, construction programmes and costs.

Ted Nye
Use of Full-Scale Field Testing in Planning and Design of Large Transport Project—An Experience from Norway

Critical transport infrastructure such as roads and railways are costly to construct, thus finding optimized safe solutions is always one of the prioritized tasks for geotechnical engineers. In Norway, the geological conditions are challenging with undulating terrain and widespread soft (frequently quick) clay dominated in many urban populated areas. In planning and design of large transport project, full-scale field testing is often used to test and optimizing geotechnical methods, hypotheses, and solutions in these challenging geological conditions Full-scale field testing is crucial before introducing, for example, a new method or an innovative design in the built environment. Over the years, the Norwegian Geotechnical Institute has conducted various field tests in connection with large road and railway projects. This paper discusses the importance of full-scale field test and presents briefly the experiences from the combined construction project (FRE16) between Ringeriksbanen national railway line and European Route 16 (E16) and from the European Road Project E6 Kvithammar-Åsen.

Christian Strømme Ofstad, Kjell Karlsrud, Sølve Hov, Thi Minh Hue Le, Jean-Sébastien L’Heureux
Perception of Geotechnical Risk and Its Impact on Project Performance

The impact of geotechnical risks on projects is often not well understood by non-geotechnical professionals. In many cases, the risks can be underestimated, and on rare occasions grossly overestimated. The impact of failing to appreciate geotechnical risks by non-geotechnical professionals is also highlighted through recent case histories where their poor perception of the risks taken has resulted in poor project outcomes. Therefore, this study aims to gain an understanding of how risks are perceived by these professionals to be able to target geotechnical risk communication more effectively.Research has been undertaken through interviewing a range of construction professionals to gauge the understanding of geotechnical risk by those who work in the geotechnical field and those in other disciplines. These include those from construction companies, government, and consultancies and cover a broad range of experiences. Views of geotechnical engineers and the profession were obtained as well as the participants' perception of the impacts of geotechnical risks on projects.

Chris Bridges, Chaminda Gallage, Bo Xia
International First In Situ Stabilised Crushed Rock for Heavy-Duty Port Pavement with 3 + lifts

Australia is currently experiencing the largest infrastructure boom in its history, with an estimated $1,177 billion of engineering work being undertaken in the last 10 years with no sign of slowing. The Port of Melbourne Rail Transformation Project currently under construction is a prime example of being limited by competing major projects and supply chain issues. The primary pavement for this project is a cement bound crushed rock (approx. 800 mm thick) with a 200 mm proprietary asphalt wearing course designed to withstand the loading from reach stackers. Due to the constraints put on this project from the competing goliath projects, access to suitable plant-mixed cement-treated crushed rock material was not possible. Therefore, an international first innovative approach of using multiple lifts of in situ stabilisation was developed to overcome the supply chain issues and still deliver a pavement that conformed to the facility’s strict performance and maintenance requirements. The new method was developed in consultation with WSP experts from Australia, New Zealand, and the UK. Rather than having the material mixed at a batch plant and brought to site ready for final compaction, unbound granular material was delivered to site and in situ stabilised. In situ stabilisation isn’t new to Australia, but due to the total thickness of the pavement, it was required to be undertaken in at least three lifts. This paper will provide an overview of the key points from the specification WSP developed for the contractor to deliver the innovative approach, and the test method adopted to determine if the crucial interlayer bonding criteria is met.

Brody Clark
Transportation Asset Management is in Need of a Dependable Foundation

As transportation owners move to manage assets in risk-informed ways, they are well served by a dependable foundation. What is meant here is not whether asset foundations are well built, but how reliably their future state can be predicted. Here we focus on ground movement, where most change is episodic and results from rare events, with the rarest events causing the most change, for example, through earthquakes, floods, and landslides. For other processes, change is more gradual and yet still occurs at a meaningful rate. Wide-area observations through aerial lidar and satellite InSAR are revealing this. A dependable Transportation Asset Management (TAM) foundation is a process where this is understood spatially and reflected in models of future performance related to safety, dependability, and cost. Another reason TAM needs a dependable foundation is so that observations made by others can be put into context. Not long ago, essentially all asset performance data and their changes were collected by the owner. Now, crowdsourcing of observations, consortiums of local owners for aerial lidar and national governments for InSAR, are ways in which observations on performance are being made by other people or interests. Owners can now find themselves being the last to know about changes to their assets rather than the first to know. In this sense, a dependable TAM foundation is a platform that provides opportunity to build from these observations, and not get turned around by them. International examples presented here demonstrate the value of a dependable TAM foundation.

Scott Anderson, Mark Vessely, Madeline Hille, Michael Porter, Sterling Mitchell, Zac Sala
Geotechnical Challenges in Infrastructure Projects—Three Case Studies

Geotechnics plays an important role in developing a competitive and sustainable infrastructure. The Ultimate Limit State (ULS) is related to the probability of failure and the safety of a structure. More challenging however is the Serviceability Limit State (SLS), where performance criteria are determining the future maintenance efforts (OPEX) and the passenger experience. Nowadays, suitable and sophisticated software tools are available. But still, the verification of the performance criteria/serviceability requirements is challenging. In addition to the software, in geotechnics, the selection of the right constitutive law and reliable soil parameters is crucial. In three case studies of global mega projects, a holistic approach for the evidence of the serviceability requirements is presented. The case studies include one of the biggest airports in the world with huge earthworks and unfavorable geotechnical conditions, the specific requirements of high-speed railways on top of earth structures, and a monorail project in challenging geotechnical conditions.

Yasser El Mossallamy, Gerhard Schulz
Digital Engineering in Infrastructure Geotechnics

This paper shares recent experience dealing with the massive site investigation dataset on a major road infrastructure project, in the context of ISO19650, and from a geotechnical engineer’s perspective. This subject project includes a freeway-to-freeway interchange, with 6.5 km of freeway widening and the associated geotechnical design of 20+ bridges and civil works. This paper demonstrates the importance of the evolving technology, which enables data-centric thinking to be applied to the geotechnical risk identification. It is shown that “first-pass” qualitative geospatial models play an important role in the early identification and quantification of design risks for the optimisation of overall design at the bidding stage. The paper discusses the process and the difficulties incorporating the variety of historical data into the project-specific geotechnical dataset, and the progressive collection, homogenisation and refinement from various sources and formats, for a dynamic collaboration with other design disciplines in regard to the geo-spatial, laboratory and field test data, thereby driving a cost-effective geotechnical design.

M. K. Peter Chan
Leveraging the Power of Modern Technologies in Planning Geotechnical Site Investigations for Mega Transportation Projects

Planning a geotechnical site investigation for a mega transportation project is a challenging task especially if a large quantum of information and data must be managed. Traditionally, the focus in planning investigations is on the product itself with little care given to the data and information used to get to the product. This paper explains how to simplify the delivery of products and reduce costs by managing the data and the information correctly. It describes: how large language processing, optical character recognition, and machine learning models can accelerate data extraction from geotechnical logs; the fundamental qualities and functions of a cloud-based geotechnical database to improve collaboration and configuration management; how parts of the reliability assessment of historic ground data can be automated; how geographical information system (GIS) can summarize the desk study information into a singular site plan to enable a more holistic interpretation of subsurface conditions. This paper discusses how novel methods can enhance the efficiency, accuracy, and precision of the desk study, geotechnical risk assessment and the scoping processes. It is based on a highway upgrade project in Queensland, Australia involving multiple new interchanges and bridges, and where novel methods were used to deliver a cost-effective scope.

Eugene Lim, Nicholas Moore, Ha Tran, Caitlin Hanrahan
Connected Geotechnical Workflows Enable Dynamic Communication Mitigating Cost Pressures and Project Risk

Large transportation projects frequently encounter issues in management of Geotechnical data, including collection, analysis, transfer, accessibility, and version control. These difficulties can lead to inefficiencies, causing cost pressures and impact the ability to communicate project risk in a timely fashion. Historically, the absence of centralized databases and effective data management frameworks bottle neck the engineer’s ability to process and interpret geotechnical data effectively. Commonly “dead end’s” form in digital data transfer as paper or pdf files are exchanged, leading to time consuming processes for digitising when updating interpretations or utilising the data elsewhere. Consequently, decision-makers and stakeholders risk lacking access to crucial data or relying on outdated geotechnical information. We propose a dynamic, connected workflow that streamlines the data transfer between applications, enhancing communication of project risk from ground conditions. Connecting cloud-based site investigation with interpretation software allows the geo-professionals the confidence to know that the latest data is being used and new data can be easily utilised to update the interpretation from a single source of truth. Additionally utilising cloud connections between interpretation software and Geotechnical analysis software, ensures numerical analysis can be consistent and quickly rerun when the Geological interpretation changes. Having subsurface interpretation in a cloud environment provides capability for more efficient communication and collaboration with all key stakeholders. It provides designers access to the latest geological interpretation which can then be utilised within their designs. The paper will include examples where these benefits are being realised on existing projects of various scales.

Richard Lowries, Anton Wu, Farzin Hamidi
Temporary Works Design Innovations for Major Rail Construction Projects

Many parts of Australia have enjoyed a rail construction boom over recent years. Increasingly stringent contractor temporary works delivery strategies have led to an increase in the safety in design focus for temporary works. In addition, the due diligence requirements of project stakeholders such as rail authorities and affected asset owners have driven the needs for multi-point geotechnical design and verification checks and sign-offs. The paper describes a number of innovative temporary works design approaches and methodologies that have been developed in response to major rail project construction sector demands. These include excavation around movement-sensitive infrastructure, temporary retention of live rail tracks, the control of rail track settlements above hard spots and ground vibration mitigation for important underground assets. The temporary works design and verification experience described have been gained through close collaboration with construction professionals on six major rail construction projects. In many cases, a significant aspect of the success of temporary works is the construction sequencing, particularly with regard to any necessary rail occupations and speed restrictions for live rail conditions. The paper describes the importance of construction sequencing in the context of overall project programming to achieve the desired outcomes in a safe environment and with stakeholder approval.

Allan Garrard, David Kolber, Jack OKelly
Design Considerations for Station Boxes and Shafts in Swelling Rock

Bringelly Shale rock is a sedimentary rock in the Sydney Basin which contains reactive clay minerals and is thus susceptible to swelling. This poses many issues with the design and construction of permanent structures such as services shafts in Bringelly Shale, considering that swelling is a time-dependent behaviour that depends on stress relief and groundwater changes. This paper covers the design considerations of two shafts located in Bringelly Shale, including modelling techniques to take into account the swelling behaviour, several design optimization and risk management strategies to manage the swelling behaviour, reduce the associated construction risk and reduce construction and material costs. Some examples are the use of a compressible layer to allow for the swelling to happen without placing undue stress on the internal primary structure, the use of free length in the base slab tension anchor design to reduce the stiffness and thus reduce the swelling-induced loads, the combined use of a Plaxis 3D models to take into account 3D effects and Plaxis 2D models to take into account the swelling behaviour using the UDSM Swelling Rock model.

Andrew Koay
Numerical Study of the Effect of Soil Water Response on Track Degradation at Transition Zones

The performance evaluation of a railway track transition zone is vital to ensure adequate track geometry and avoid excessive material deterioration that could in turn lead to an increase in maintenance requirements and frequent disruptions to freight and passenger services. While several different engineering solutions have been proposed in the past to address the stiffness variation and differential settlements observed in transition zones, the importance of soil water response is not commonly considered in the design and construction of transition zones. However, the consideration of the impact of a seasonal change in moisture that takes place in transition wedges is critical in view of more extreme climate patterns associated with climate change. This paper explores the role of water content and water retention on the stiffness of an engineered wedge transition zone using a numerical model developed in Plaxis 3D while using the Barcelona Basic Model (BBM) constitutive model. Two types of simulations were conducted. First, a rainfall event was simulated using transient flow analysis and then the vertical displacement associated with traffic load (InterCity Express rolling stock) was calculated using a pseudo-dynamic analysis. The results indicate that for the same rainfall event, the wedge engineered materials having a higher initial suction remain in partially saturated conditions for longer periods and hence the vertical deformation during loading is reduced. This implies there is an opportunity to reduce track degradation by engineering granular materials incorporated in the transition wedges, particularly in terms of their water retention capacity.

Jorge León Illanes, Ana Heitor
Effect of Stiffness Variation of Blanket Layer in Formation Layers on Dynamic Response of Ballasted Track Transition Zone

The dynamic response of ballasted track transition zones is a critical aspect in railway geotechnics, affecting the performance of track geometry. Track stiffness and ballast stress are used as key parameters in finite element (FE) numerical simulations for several types of subgrade soils prevailing in the Indian subcontinent with elastic modulus (E) ranging from 30 to 100 MPa. A smooth transition in stiffness variation at the transition zone has been investigated by providing a blanket layer with varying elastic modulus on the top of the subgrade soil. Provision of a blanket layer results in a 38–55% reduction of stresses transferred to the subgrade, thus preventing subgrade failure, mud pumping, and moisture variation in the subgrade that are commonly encountered in the field. Further, the dynamic response is evaluated for two different axle loads, 25 T and 32.5 T, and two different speeds, 120 km/h and 160 km/h, respectively, to assess the track’s performance during typical operational conditions as per standard guidelines of the Indian Railways. The ballast stress and track stiffness are also probed for different initial differential settlements (DS) at the transition zone. The findings of the current study contribute to the design, construction, and maintenance of the ballasted tracks, enabling enhanced performance of railway infrastructure.

Suman Haldar, Anish Kumar Soni, Kirti Choudhary, Debayan Bhattacharya, Bappaditya Manna
Stiffness Optimization for Ballasted-Ballastless Track Transition Zones in High-Speed Railways

In order to reduce the vibration response of high-speed trains in the ballastless-ballasted track transition zone, a vehicle-track-subgrade coupled dynamic finite element computational model was established. The dynamic response characteristics of the vehicle and track structure were studied by considering different structural treatment measures such as adjusting the stiffness of rail pads, and installing concrete transition slabs and ballast bonding. Adjusting the rail pad stiffness, installing concrete transition slabs, and improving ballast bonding significantly influence the overall vertical stiffness of the track, offering the possibility of optimizing the stiffness of the transition zone through these measures. Concrete transition slabs are particularly effective in reducing the vertical vibration response of the train, while ballast bonding increases the track stiffness, requiring a simultaneous reduction in the stiffness of under-sleeper pads to mitigate wheel-rail forces. The length of concrete transition slab needs to be adjusted according to the actual situation due to the excessive length of transition slab that would increase vehicle vibration response. When the smoothness of track in transition zones is poor (such as the presence of track deflection angles), the vibration response of vehicle is mainly affected by track irregularity and the influence of stiffness transition measures on the vibration response of vehicle is relatively limited.

She-Hui Tan, Wei Liu, Xi Liu, Yao Shan
A High-Speed Railway Transition—An Innovative Solution for a Pleasant Journey

Design and construction of sustainable railways are becoming essential to connect resilient communities; whilst addressing the challenges caused by climate change and achieving global targets for decarbonization. To reach these targets, a modern sustainable and low carbon high-speed railway is required to meet very stringent safety and performance criteria, have longevity, be highly reliable, and provides delightful passengers’ experience. The geotechnical engineer’s involvement is considered paramount during the planning, design, and construction of a homogenous railway track over viaducts, embankments, culverts, cuttings and tunnels, the performance of which is highly dependent on the behaviour of the ground upon which these are founded. This paper presents an overview of the design and construction of high-speed railway transitions adopted in different countries, using national and international standards. The paper also presents an innovative approach based on case studies of high-speed railway track transitions that combined safety, constructability, efficiency, and sustainability. This solution was based on modelling of static and cyclic-dynamic loading conditions, taking in consideration the construction sequence to achieve a smooth transition from earthworks to structures and vice-versa. This solution has been successfully adopted and its high operations performance has been proven in several high-speed railway projects.

Gerhard Schulz, Ouarda Boumendjel-Game, Yasser El Mossallamy
Study on Differential Settlement of Bridge-Subgrade Transition Section Using DEM-MBD Coupling Method

In order to investigate the uneven settlement of bridge-embankment transition section, a full-scale three-dimensional transition zone model has been proposed, which utilizes a coupling approach involving the Discrete Element Method (DEM) and Multibody Dynamics (MBD). The coupled DEM-MBD model was developed to analyze the behavior of wedge-shape backfill treatment from macro and micro views. M-wave loading pattern was applied, and the accuracy of this comprehensive model was validated by replicating uneven settlement patterns under train loading. Simulation results show that the wedge backfill reinforcement significantly inhibits sleeper settlement, with the maximum settlement of sleepers in the transition subgrade area decreasing from 2.04 mm to 1.38 mm, a reduction of 32.1%. The uneven settlement in the transition section decreases from 1.51 mm to 0.92 mm, a reduction of 39.1%. Furthermore, the use of wedge backfill increases the number of ballast particles transmitting contact forces beneath sleepers. The contact force chains in the ballast layer disperse with a larger angle, effectively strengthening the support of the track bed. Simultaneously, the particle velocity beneath the sleepers decreases significantly with wedge backfill, restraining particle motion, and thereby reducing sleeper settlement at a macro level.

Cheng Chen, Cheng-lu Zhang, Xiao-dong Lin, Pei Tai
Effects of Voiding on the Performance of Fixed Diamond Railway Crossings

Switches and Crossings (S&C) are an important component of a railway track system, used to direct trains between different paths. They constitute approximately 2% of UK track, but account for 23% of annual track renewals and consume 24% of the annual track maintenance budget. One of the contributing factors is the effect of poor or variable geotechnical support from the underlying substructure (the ballast/and or underlying geology), which can lead to amplified dynamic and impact loads and voiding beneath the track. This paper presents an initial assessment of the history of track geometrical performance of two S&C suspected of underlying geotechnical issues. The initial assessment is based on historical data from the Linear Asset Decision System (LADS) of the UK railway infrastructure owner and operator Network Rail (NR), supplemented by evidence from on-track inspections. The aim is to identify features and behaviour linked to possible underlying geotechnical issues for targeted and detailed investigation, including strategic on-track monitoring. The study is based on an historically problematic junction and a recently renewed junction on the UK railway network. A qualitative assessment of the evidenced behaviour of each asset is used to identify areas of suspected voiding beneath the track. This will assist in future investigation of crossing behaviour in relation to the importance and benefits of consistent geotechnical support for optimal S&C performance.

Akeem Faniran, David Milne, William Powrie
Metadaten
Titel
Proceedings of the 5th International Conference on Transportation Geotechnics (ICTG) 2024, Volume 3
herausgegeben von
Cholachat Rujikiatkamjorn
Jianfeng Xue
Buddhima Indraratna
Copyright-Jahr
2025
Verlag
Springer Nature Singapore
Electronic ISBN
978-981-9782-21-5
Print ISBN
978-981-9782-20-8
DOI
https://doi.org/10.1007/978-981-97-8221-5