Buried Infrastructure Research Articles

Evaluating soil thermal conductivity for buried infrastructure: Impact of water salinity, mineral composition, and moisture content on heat transfer

Thermal conductivity of soils is a critical soil property in geotechnics, which provides essential information about the soil's ability to conduct heat transfer. Erroneous data can be responsible for the inefficient design of buried infrastructure systems that rely on heat transfer, such as buried cables, piping, and geothermal systems. There is a lack of fundamental knowledge on the soil thermal conductivity under in-situ conditions factoring soil type, alteration in moisture content, and salinity. Our research aims to address how groundwater, flooding, or drought can impact thermal conductivity due to moderate-to-high soil salinity levels; as these may be critical factors to be considered in soil thermal conductivity testing for infrastructure. This study investigated the influence of salinity concentrations on soil thermal conductivity, with potential implications for areas with a high water table, rainfall, or flooding events, as well as offshore wind projects. This study accounted for variations in soil type and water salinity concentrations when testing for the thermal conductivity of soil. Twenty-three (23) experimental tests were conducted with a resulting 36 thermal conductivity data points recorded. The results were further analyzed in comparison with data results obtained from using the current industry-accepted methodology, which does not account for varying salinity concentrations. The results suggest that sand soil was most conductive when added with 15 g/L brine. Further, the salinity concentration or soil type can increase (silty clay) or decrease (sandy soil) soil thermal conductivity at varying moisture contents, which could provide a more informed, economical design for buried infrastructure that relies on heat transfer through soils.

Intelligent measurement method of transition resistance of insulation fasteners in urban rail transit system based on SSA-optimized algorithm

Rail-to-earth transition resistance characterizes the amplitude of stray current leakage in urban rail transit system using electric traction, which is critical for evaluating failure risk of metal infrastructures caused by electrochemical corrosion. However, detection method commonly used in the field exhibit measurement errors resulting from the limitation of measuring principle and measuring distance, which will seriously affect the accuracy of electrical insulation performance evaluation of the whole system. In view of this, this paper proposes a data-driven method for accurately measuring rail-to-earth transition resistance in urban rail transit system based on CDEGS-based simulation and SSA-optimized algorithm. CDEGS model was built to construct database for machine learning of SSA-RF network structure. SSA algorithm was used in the measurement model to optimize the topology of the random forest (RF) structure. Proposed ensemble in this paper was proved to conduct transition resistance regression with a mean relative accuracy rate of 98.85 %. Results of sensitivity analysis indicate that proposed measurement method shows acceptable robustness, which allows the algorithm parameters to fluctuate within a certain range when applied in the field. Besides, in the case of uniform and non-uniform insulation degradation, the proposed method shows good performance in assessing insulation performance. This provides a feasible foundation for future applications of the proposed method in failure risk evaluation of buried infrastructures.

Impact of flooding events on buried infrastructures: a review

This review delves into the profound implications of flooding events on buried infrastructures, specifically pipelines, tunnels, and culverts. While these buried infrastructures are vital for community resilience, their susceptibility to damage from flooding, storm surges, and hurricanes poses significant challenges. Unlike the obvious impact on above-ground structures, the effects of flooding on buried infrastructures, being out of sight, are not quickly and easily observable. This review aims to 1) review the state-of-the-art research on the flooding effects on buried structures and summarize causes of failures of buried infrastructures induced by flooding; 2) identify the research gaps on this topic to motivate in-depth investigations; and 3) discuss the future research directions. This review sheds light on how factors contributing to the vulnerability of buried infrastructures are multifaceted and can vary based on the specific characteristics of the infrastructure, the local environment, and the nature of the flood event. Despite the availability of many articles on the topic, this review also highlights a lack of methodologies to assess flooding damage and its impact on the serviceability of buried infrastructures. We suggested three future research directions to bridge this research gap including investigating and distinguishing key factors to quantify flooding damage to buried infrastructures, developing advanced modeling techniques, and exploring the integration of smart technologies in health monitoring of buried infrastructures.

The Application of High-Resolution, Embedded Fibre Optic (FO) Sensing for Large-Diameter Composite Steel/Plastic Pipeline Performance under Dynamic Transport Loads.

Distributed optical fibre sensing (DOFS)-based strain measurement systems are now routinely deployed across infrastructure health monitoring applications. However, there are still practical performance and measurement issues associated with the fibre's attachment method, particularly with thermoplastic pipeline materials (e.g., high-density polyethylene, HDPE) and adhesive affixment methods. In this paper, we introduce a new optical fibre installation method that utilises a hot-weld encapsulation approach that fully embeds the fibre onto the pipeline's plastic surface. We describe the development, application and benefits of the new embedment approach (as compared to adhesive methods) and illustrate its practical performance via a full-scale, real-world, dynamic loading trial undertaken on a 1.8 m diameter, 6.4 m long stormwater pipeline structure constructed from composite spiral-wound, steel-reinforced, HDPE pipe. The optical frequency domain reflectometry (OFDR)-based strain results show how the new method improves strain transference and dynamic measurement performance and how the data can be easily interpreted, in a practical context, without the need for complex strain transfer functions. Through the different performance tests, based on UK rail-road network transport loading conditions, we also show how centimetre- to metre-scale strain variations can be clearly resolved at the frequencies and levels consistent with transport- and construction-based, buried infrastructure loading scenarios.

The hidden consequences of sea level rise: assessing vulnerability of buried infrastructure to groundwater inundation in American Samoa

Abstract To island nations, sea level rise (SLR) is an existential threat. An insidious and often hidden consequence of SLR is groundwater inundation (GWI), which reduces the unsaturated zone causing flooding, enhanced corrosion, and reduced service life of buried utilities. In the Pacific, SLR may reach 0.6–2.5 m by the end of century, and on Tutuila, American Samoa (AS), apparent SLR is five times the global average, making adaptation planning critically important. This study addresses the climate impact-knowledge-gap regarding AS's infrastructure by combining a numerical groundwater model with buried and surface utility data to map where adaptation efforts should be prioritized. Rigorous studies of GWI are few, and this study is the first to model this phenomenon in the South Pacific. The model estimates that 70 km or 45% of the buried water, electrical, and sewer lines will be inundated, and 28% of present-day roads, 13.6% of buildings, and 20% of water-booster stations will be permanently flooded under a 2.4-m SLR scenario with projected recharge in 2100. These effects are often overlooked by or unknown to policy and decision makers; therefore, building awareness of GWI will help managers in AS and in other island communities to prioritize holistic adaptation actions.

Stray current induced ITZ effect on chloride transport in concrete

Understanding the influence of interface transition zone (ITZ) on chloride migration characteristics in concrete under coupled stray current and high hydraulic pressure is essential to solve the durability problem of ultra-deep buried infrastructures (40 m-100 m). Herein, an advanced test system is developed and the chloride migration characteristics of deeply buried concrete is comprehensively investigated. Specimens were casted with the same aggregate volume content but different aggregate size distribution. The ITZ between aggregate and cement matrix was measured from BSE (back scattered electron imaging) images, and the ITZ thickness was measured by Vickers hardness. The silver nitrate spray was used to determine the chloride migration front, and the effective diffusion coefficient was calculated. The results showed the concentric expansion and overflow method based on BSE images were effective ways to determine ITZ porosity distribution. The significant increase of ITZ thickness and porosity on concrete reaction surface under stray current environment was observed and defined as “stray current induced ITZ effect”, which was considered to be the fundamental reason for the distinct differences in chloride migration depth and effective diffusion coefficient of specimens with different aggregate gradations.

Comparison of the effects of anthropogenic seismic events and natural earthquakes on buried infrastructure network components

Comparison of the effects of anthropogenic seismic events and natural earthquakes on buried infrastructure network components

Mapping soil corrosivity in an Australian arid environment and comparing corrosion rates of exclusion fence netting with different zinc coatings

Exclusion fencing and feral-free nature reserves are a key component of many threatened species recovery strategies in Australia. Soil corrosion damage (rust) sustained on exclusion fence netting can create entry points for feral animal incursions into areas of high conservation value. The use of soil physicochemical data to produce corrosivity risk maps is an approach used by project managers to identify the type of corrosion control measures (e.g. use of galvanised zinc coatings) needed to sufficiently limit the deterioration of buried metal infrastructure. This approach is commonly used in subsoil environments (e.g., underground piping), but very few studies have investigated the corrosivity potential of surfaces soils. This paper used surface soil pH, salinity and texture data collected from 69 field sites to map soil corrosivity potential (i.e., fence corrosion risk) at the Arid Recovery nature reserve in South Australia. The majority (72%) of soils in the reserve were predicted to be moderately corrosive and only 16% were predicted to be highly/very highly corrosive. Standard zinc-aluminium fence netting samples buried at six field sites for 18 months were used to validate map predictions. Zinc corrosion on netting samples at field sites were highly variable, particularly at the highly saline (ECe ≥ 5 dS/m) sites. Maximum predicted zinc corrosion rates were within 1.3 μm/year of measured maximum rates at four of the six sites. The fence corrosion risk mapping method used was able to reliably predict areas of low to moderate fence corrosion, but further research is needed to refine its ability to identify high risk areas. An accelerated corrosion experiment (9-month incubation at 65% WHC and elevated ambient temperatures) was used to assess the relative performance of standard zinc-aluminium (124 g/m2 zinc coating), heavy zinc-aluminium (410 g/m2) and heavy galvanised (650 g/m2) fence netting in different soil environments present on the nature reserve. The standard zinc-aluminium wire coating provided sufficient corrosion-resistance for use in the weakly saline (ECe < 5 dS/m) soils (Rhodic Arenosols, Calcic Chromic Solonetz and Chromic Cambisols). However, the increased corrosion-resistance of the heavy zinc-aluminium is needed in the highly saline (ECe ≥ 5 dS/m) Chromic Luvisol. None of the tested fence products were suitable for use in the highly saline Cambic Calcisols. A more corrosive-resistant alternative such as stainless-steel would be more suited for this very highly corrosive environment. Further research is recommended to confirm the long-term (>5 year) suitability of these products in these different soil types.

Integrated Three‐Dimensional Geological and Numerical Groundwater Model Development

AbstractConceptual site model (CSM) development is a foundational step for numerical groundwater model construction. Tools for reviewing and combining disparate data to develop a CSM have been furthered through software that efficiently integrates multiple data streams, especially when a large amount of information is available at complex sites. Three‐dimensional (3D) interfaces for data visualization and geological modeling are becoming commonly used to compile data, support development of a robust CSM, and create effective visuals that enable project stakeholders to understand site complexity. This article describes a 3D interface workflow applied to a geological and numerical groundwater modeling case study where numerical modeling (i.e., MODFLOW family of codes) was used to assess remedy effectiveness. Specifically, the numerical model was used to overview an in situ solidification (ISS) application, where soil mixing will be conducted with cement, for possible adverse effects to an existing groundwater treatment system. 3D geological modeling allowed for the existing numerical groundwater flow model to be reconstructed to include previously overlooked data on buried infrastructure, which led to a detailed depiction of high‐permeability channels and a more accurate representation of site conditions. Modeling showed that the ISS remedy would not adversely impact the existing groundwater treatment system. Integration of existing data within a 3D interface led to hydrogeological insights that would have been difficult to obtain from two‐dimensional visualization of information, improved numerical modeling efficiency, and informed site remedy decisions. Additionally, the 3D interface created effective visuals that increased internal and external project team conceptual understanding.

Direct current resistivity and time domain induced polarization methods in soil corrosivity assessment for buried infrastructure

Direct current resistivity and time domain induced polarization methods in soil corrosivity assessment for buried infrastructure

Numerical Study on Urban Infrastructure Diagnosis in Laterally Heterogenous Soils Using Resistivity and Ground Penetrating Radar Techniques

Urban environment can be considered a complex system consisting of the engineered pavement physical structure over the buried utilities (water, gas, sewer) network embedded in the background soil environment. Assessment of buried pipeline civil infrastructures using proximal geophysical methods in such instances has to consider possible interferences, difficulties, and incorrect inferences. In this study, we have conducted a numerical modelling investigation to understand and evaluate how electrical resistivity profiling (ERP) and ground penetrating radar (GPR) can be utilised to provide subsurface information that otherwise may not be possible if either one of the techniques is used. A model geometry consisting of a typical pavement structure (asphalt, base/subbase, and background soil) with a single 2 m pipe buried at a depth of 1 m was used. Strong lateral variations in soil type were incorporated over the short pipe section in order to understand the complexities that can arise, especially with ERP measurements. The 3D electrical resistivity measurements were simulated in Comsol using the 4-probe method, while the 2D GPR measurements were simulated in gprMax to obtain the subsurface information. The results from both ERP and GPR were used to develop a practical framework that can be utilised by relevant authorities for proximal condition assessment of their buried assets. It was suggested that ERP can be used as a first level screening tool over the whole pipeline length, followed by discretely selected GPR scans in order to further gain information on the pipe health. This is attractive practically since, following delineations of a large pipe section into shorter subsections, advanced condition assessment approaches that are generally intrusive in nature can then be economically deployed within the subsections suspected of experiencing significant corrosion damage.

Investigating temporal dynamics of urban densification on the buried water infrastructure performance

Urban densification has dominated the land uses and land covers which may jeopardize the quality of life and sustainable development. Moreover, urban densification process exerts stress on buried water infrastructure (BWI) performance. In this study, the need of predicting the change in urban densification and its subsequent impacts on BWI performance over time has drawn attention to conduct a temporal analysis. A hybrid approach was used to select the significant control performance indicators (CPIs) and conduct a temporal analysis. Eight scenarios were generated using the Canadian Council of the Ministers of the Environment Water Quality Index approach to address the change in drinking water quality. The proposed approach was implemented in a municipality of British Columbia, Canada, as a case study. The results showed a 40 % decrease in the BWI performance due to the urban areas have rapidly grown both in population and built-up areas over three decades. Furthermore, an ideal situation was assumed to show that the targeted service level (i.e., 0.5) can be achieved with 3 % to 5 % improvement in every five years of service level. These findings will assist the decision makers to understand the linkage between CPIs to maintain and achieve the required BWI performance.

Impact of stormwater infiltration on rainfall-derived inflow and infiltration: A physically based surface–subsurface urban hydrologic model

The subsurface fate of stormwater infiltration enhanced by green infrastructure (GI) is unknown. GI redirects stormflows from the surface into the subsurface, which can be partitioned to evapotranspiration or baseflow, or be intercepted by buried infrastructure trenches. Stormwater that infiltrates sanitary sewer pipes is referred to as rainfall-derived inflow and infiltration (RDII) and represents a rapid pathway for infiltrated stormwater to reach receiving waters. To quantify the partitioning of infiltrated stormwater between slow and fast flows, a physically-based hydrologic model was developed integrating coupled surface–subsurface processes and urban sewer systems and applied to a sewershed near Milwaukee, WI. In this region with shallow groundwater table and leaky sanitary sewer systems, RDII accounted for 73–79% of the sanitary sewer flow volume and 21% of the sewershed water balance. Sensitivity analysis indicated that the surface direct inflow was controlled more by precipitation/evapotranspiration ratio and the subsurface infiltration was controlled more by groundwater table depth and sanitary sewer defect density. The largest effect of GI was to shift surface runoff to evapotranspiration and reduce peak flow in urban sewer systems. The volume of RDII was relatively less sensitive to GI infiltration because reductions in directly connected surface runoff were offset by increases in groundwater inflow. A moderate level of GI implementation (5–10% replacement of impervious area) reduced RDII volume by 10%, however, these changes were less than 1% of the overall water balance. On the other hand, higher levels of GI implementation (∼20% replacement of impervious area) resulted in no change to RDII volume as more infiltrated stormwater was routed to the sewer system through the subsurface. This study highlights the necessity of considering the full hydrologic context of GI and balancing the runoff reduction by GI and groundwater infiltration into sewers.

Structural Performance of Fusion Weld Based on Weld Parameters and Strain Rate in High-Density Polyethylene

Abstract Use of high-density polyethylene (HDPE) material has increased considerably in the last few decades to form long installation lengths of buried infrastructure such as water mains, sewers, and gas pipelines. These pipes are available in standard length sections and joined together to get customized length using fusion-welding techniques. The strength of welds highly depends on welding parameters such as temperature, heat, and soaking time. The structural performance also varies with respect to strain rate. In this paper, the strength of fusion-welded HDPE material is analyzed under different welding parameters and variable strain rates of welded and unwelded samples. An additional important aspect of the present research is to study the structural performance of fusion welds made between extruded HDPE pipes and injection molded HDPE fittings, i.e., elbows, Tee joints and closed-end cap connections. The strain-rate sensitivity index is measured with variable strain rates during tensile testing. The findings of this research can help in understanding and improving the structural performance of HDPE fusion-welded joints in various applications.

Using paleomagnetism to determine the heating effect of lava flows on underlying substrates

The extent to which heat from lava flows passes into underlying and adjacent materials has significant implications for volcanic hazard studies. Here we demonstrate how paleomagnetism can be used as a tool to determine the heating effects of lava flows in the pre-existing substrates over which they flow. Samples from soils taken beneath lava flows from Rangitoto and Puketutu eruptive centres (Auckland Volcanic Field, Aotearoa New Zealand) and a human-made berm beneath the June 27th Lava Flow (2014–2015; Kīlauea Volcano, Hawaii, USA) were subjected to progressive thermal demagnetization to assess the strength and stability of their remanent magnetizations. The temperature and depth to which these soils display a strong coherent magnetization represents the extent to which they were remagnetized (and therefore heated) by the overlying flow. Results suggest heating to at least 570 ℃ at depths of up to 21 cm below the substrate-flow contact. This information is valuable for constraining and validating heat transfer models, which can be used to assess the lava flows’ subterranean thermal hazard. Among many uses, this is vital for emergency management planning for buried infrastructure networks traversing regions that could be exposed to effusive volcanic activity. Further afield, in astrobiology, it might find application in determining the thickness of a substrate layer heated sufficiently by a lava flow to kill living organisms.

A Governance Framework for Implementation of Scientific and Engineering Innovation in Buried Infrastructure Systems

This article draws on experience within a pervasive sensing research project, the Pipebots project. The aim of the project is to design miniature robots to gather physical condition and environmental data on buried pipe networks, using potable water distribution and wastewater pipe systems as the initial target applications. One of the challenges of the project is to anticipate and address the potential governance issues triggered by the project. Due to the lack of a suitable tool with sufficient breadth to guide thinking, the existing literature has been drawn upon to form the basis of a governance framework for use in infrastructure projects. Whilst the original intention was to be alert to and interrogate the forms of governance that may impact on new infrastructure interventions, what is emerging is a tool that would support the strategy for implementation, improve the design (a no-regrets design policy) and help build the business case for the transformational change the project envisages.

Heat recovery and thermal energy storage potential using buried infrastructure in the UK

Dispersed space heating alone accounts for 40% of UK energy use and 20% of carbon dioxide (CO2) emissions. Tackling heating and building cooling demands is therefore critical to achieve net-zero ambitions in the UK. The most energy-efficient way to reduce the carbon dioxide emissions of heating and cooling is through the use of ground-source heat pumps and district heating technology. However, capital costs are often high, sometimes prohibitively so. To reduce investment costs, it is proposed to use buried infrastructure as sources and stores of thermal energy. Barriers to this innovative approach include lack of knowledge about the actual net amount of recoverable energy and impacts on the primary function of any buried infrastructure, as well as the need for new investment and governance strategies integrated across the energy and infrastructure sectors. Additional opportunities from thermal utilisation in buried infrastructure include the potential mitigation of damaging biological and/or chemical processes that may occur. This paper presents a first assessment of the scale of the opportunity for thermal energy recovery and storage linked to new and existing buried infrastructure, along with strategic measures to help reduce barriers and start the UK on the journey to achievement of its infrastructure energy potential.

Leveraging risk and data analytics for sustainable management of buried water infrastructure

AbstractA proactive and sustainable asset management program is vital for utilities to maintain their capital assets at the required level of service, while ensuring that adequate funds are available for intervening when needed on their riskiest assets. One of the most popular methods for building such programs is by prioritizing capital investments based on the asset's risk of failure, which evaluates its likelihood or probability of failure and impact, or consequence of failure. This paper presents the application of a financial planning analysis using system dynamics to provide insights into quantifying more practical risk avoidance. This is exemplified through a 5‐year budgetary planning scenario analysis for a large‐sized US water utility to help the utility best plan for short and long‐term capital operations and show the value of a data‐driven and risk‐based decision‐making.

Briefing: Plexus: Priming Laboratory Experiments on Infrastructure and Urban Systems

The UK Collaboratorium for Research on Infrastructure and Cities (UKCRIC) is, with a capital investment of £138 million from the UK government and matched funding from its 15 collaborating partner universities, creating world-class city observatory and modelling and simulation and physical laboratory facilities. This briefing aims to introduce UKCRIC’s formulation, capabilities and core thinking, before describing a programme of work that has linked the 11 laboratory facilities. Priming Laboratory Experiments on Infrastructure and Urban Systems (Plexus) has focused on three important technical challenges – intense physical interdependency of urban infrastructure systems, harvesting energy from buried infrastructure systems and accelerated deterioration of infrastructure materials due to extreme loading – as well as a study of how the large, multidisciplinary research team progressed towards transdisciplinary working. The background context of UKCRIC, its approach to collaborative research and how this has shaped the Plexus research programme provides the starting point to this narrative. Thereafter the underpinning thinking and justification for the four strands of Plexus’s research are described. Finally, the briefing draws these strands together into a proposition for the research, development and implementation of a new generation of transport bridges building on the research reported in this special issue.

Evaluation and comparison of different detection technologies on simulated voids near buried pipes

Erosion voids near buried pipes may reduce the service lives of buried infrastructure assets and present a concern to municipalities as they are difficult to detect accurately and effectively. Various technologies exist to detect erosion voids but limited testing has been performed to evaluate their effectiveness. In order to evaluate and compare different existing erosion void detection technologies, a blind experiment (i.e., without operators having prior information about void locations and geometries) was conducted. Two kinds of pipes were used for the evaluation: a corrugated steel pipe and a reinforced concrete pipe. A total of five artificial voids were made near the pipes. Four commercially available void detection technologies were evaluated: (i) conventional Backscatter Computed Tomography (BCT), (ii) handheld BCT, (iii) Ground Penetrating Radar (GPR) and (iv) Pipe Penetrating Radar (PPR). Additionally, Infrared Thermography (IRT) was also employed by the authors although this was not a blind study. Each technology and the data provided by that technology are presented. Based on the results, Handheld BCT and IRT were recommended for initial detection of the voids near corrugated steel pipes. To obtain higher accuracy and geometry detail, conventional BCT and PPR were suggested for the corrugated steel pipe and concrete pipe, respectively. GPR was able to detect a large void simulated between the two test pipes.