Ground Temperature Research Articles

Impact of Tunnel Fire and High Ground Temperature on the Durability and Thermal Damage Mechanism of Structural Materials

The goal of this paper is to investigate how tunnel fires and high temperatures interact to reduce the structural and thermal properties of tunnelling materials, namely concrete and steel. The work looks at microstructural modifications in concrete (pore expansion, micro-cracking, and the chemical degradation of calcium silicate hydrate (C-S-H) that reduce compressive strength and make concrete porous). Oxidation, surface scaling and yield strength degradation under high temperature are studied in steels to evaluate their negative impact on the capacity to carry loads. The paper also incorporates simulated data on how the insulation material performs over time as a result of repeated high-temperature exposure. Such results emphasise the double-edged structural hazard of fire and geothermal heat, which hastens material decomposition, weakens robustness and undermines long-term stability of critical infrastructure. The paper ends with suggestions for new, thermophilic materials to make tunnels safer in extreme conditions

Influence of Row Pattern and Prohexadione Calcium on Peanut (Arachis hypogaea L.) Maturity and Pod Distribution

Many newer peanut cultivars are offering improved yield benefits but have larger canopies and have taken 10 or more days longer to reach maturity levels that were historically desired for optimal profitability of a crop. Prohexadione calcium growth regulator and twin row planting pattern have previously been individually reported to increase the amount of orange, brown or black pods compared to untreated alternatives. Twin row planting (i.e., planting two rows spaced 18-cm apart on 96-cm centers) has additionally been anecdotally associated with increased concentrations of pods nearer the taproot. Objectives of this work were to evaluate maturity development in single versus twin row planted peanuts and to evaluate how prohexadione calcium application would affect maturity development and pod distribution of both single and twin row planted peanut. Four cultivars were selected based on frequency of use in South Carolina then paired into experiments based on maturity requirements. Experiments were conducted at the Edisto Research and Education Center in Blackville, SC and the Pee Dee Research and Education Center in Florence, SC in 2021 and 2022. Peanut planted in twin row planting pattern yielded greater and had a higher percentage of orange, brown or black pods and total sound mature kernels. For FloRun 331 and Georgia-16HO in twin but not single rows, prohexadione calcium treatment increased the percentage of orange, brown or black pods. Although pod distribution effects for twin rows without and single rows with prohexadione calcium varied by maturity group, twin rows with prohexadione calcium exhibited pod distributions closer to the taproot than treated single rows. Twin row plots were associated with cooler ground temperatures than single rows, while the effects of prohexadione calcium on ground temperature varied between cultivars. Increased ground temperature was negatively correlated with pod maturity and main stem heights. Results from this work contribute to our understanding of potential benefits and variability across cultivars of the use of twin row planting pattern and prohexadione calcium treatment.

Mechanical Behavior and Failure Mechanism of Rock–Concrete Composites Under the Coupling Effect of Inclined Interface Angle and Ground Temperature

Surrounding rock and lining are composite structures with asymmetric mechanical properties. Understanding the mechanical properties and failure characteristics of rock–concrete composites is crucial for gaining insights into the mechanisms that induce disasters in deep-underground environments. Uniaxial compression and acoustic emission tests were conducted on rock–concrete composite specimens cured at temperatures of 20 °C, 40 °C, 60 °C, and 80 °C, with interface angles of 15°, 30°, 45°, 60°, 75°, and 90° respectively. The results indicated that the specimens’ strength decreased at increasing geothermal temperatures. The composites with an 80 °C curing temperature and a 60° interface angle exhibited the lowest strength. A higher geothermal temperature significantly reduced the number of cracks in the concrete component during composite failure and mitigated the influence of the inclined interface angle. The failure modes of the specimens include axial penetration splitting, interface shear, Y-shaped fracture, and interface splitting–concrete shear failure. Finally, a model relating the strength of the rock–concrete composite to the inclined interface angle and the geothermal temperature was derived and verified against the experimental results with a relative error of 9.8%. The findings have significant implications for the safety and stability of tunnels in high-temperature conditions.

High‐Temperature Oxidation Behavior and Grinding Performance of CoCrFeMnNi High‐Entropy Alloy

Herein, the mechanical properties, oxidation behavior, and processing performance of the CoCrFeNiMn high‐entropy alloy are investigated using multiple characterization methods. The alloy exhibits a yield stress of 462 MPa, an ultimate tensile strength of 1037 MPa, and a fracture strain of 31.8% at room temperature. Oxidation tests reveal that the oxide layer consists of an outermost oxide layer and a Cr2O3 layer at both 1000 and 1200 °C. The Cr2O3 layer formed at 1000 °C is dense and continuous, whereas it transitions from continuous to discontinuous as the temperature increases to 1200 °C. Localized peeling of the oxide layer is observed at 1200 °C due to the diminished protective effect of the Cr2O3 layer and the increased stress in the oxide layer caused by the formation of multiple complex oxides. Grinding experiments indicate that both the grinding force and surface roughness increase as the load increases. Additionally, energy‐dispersive X‐ray spectroscopy results show that the oxygen content of particles at a 120 N is higher than at 60 and 90 N, suggesting an elevated grinding temperature at 120 N, which leads to the formation of bonded convex particles.

A 30-Year Analysis of Forest Cover and Land Surface Temperature in Attapeu Province, Lao PDR

Changing forest areas can have a complex range of impacts on ground temperatures, from increasing temperatures due to loss of shade to creating drier and hotter local climate environments. This study aims to identify spatiotemporal changes in forest cover and retrieve land surface temperature (LST) using thermal infrared sensor (TIRS) data in Attapeu province, Lao PDR from 1994 to 2024. Geographic information system (GIS) techniques were employed to extract spatiotemporal changes in land use and land cover (LULC) and Normalized Difference Vegetation Index (NDVI). The analysis of LULC change revealed a notable decrease of 18.43% in dense forest areas, accompanied by an increase of 7.87% in sparse forest and 11.35% in cropland, indicating a transition from dense forest to sparse forest and cropland for the study area. The analysis of LST utilizing TIRS revealed a consistent negative correlation with NDVI. The coefficient of determination (R2) indicated values of 0.5896 in 1994, 0.5691 in 2009, and 0.4344 in 2024. By correlating remotely-sensed thermal data with in situ observations, this research delineated the prolonged alterations in LST due to fluctuations in forest cover. The urgency of enacting policies is underscored to mitigate the ongoing loss of forest cover. These findings emphasize the need for immediate policy actions, such as enhanced forest conservation and reforestation programs, to mitigate rising temperatures and ensure ecological sustainability in Attapeu province. The insights garnered from this investigation hold significant implications for the conservation endeavors aimed at preserving the forests of Attapeu province.

Observation Angle Effect of Near-Ground Thermal Infrared Remote Sensing on the Temperature Results of Urban Land Surface

During the process of urbanization, a large number of impervious land surfaces are replacing the biologically active surface. Land surface temperature is a key factor reflecting the urban thermal environment and a crucial factor affecting city livability and resident comfort. Therefore, the accurate measurement of land surface temperature is of great significance. Thermal infrared remote sensing is widely applied to study the urban thermal environment due to its distinctive advantages of high sensitivity, wide coverage, high resolution, and continuous measurement. Low-altitude remote sensing, performed using thermal infrared sensors carried by unmanned aerial vehicles (UAVs), is a common method of land surface observation. However, thermal infrared sensors may experience varying degrees of sway due to wind, affecting the quality of the data. It is still uncertain as to what degree angle changes affect thermal infrared data in urban environments. To investigate this effect, a near-ground remote sensing experiment was conducted to observe three common urban land surfaces, namely, marble tiles, cement tiles and grasses, at observation angles of 15°, 30°, 45°, and 60° using a thermal infrared imager. This is accompanied by synchronous ground temperature measurements conducted by iButton digital thermometers. Our results suggest that the temperature differences between the remote sensing data of the land surface and the corresponding ground truth data increase as a function of the increasing observation angle of the three land surfaces. Furthermore, the differences are minor when the observation angle changes are not more than 15° and the changes are not the same for different land surfaces. Our findings increase the current understanding of the effects of different angles on thermal infrared remote sensing in urban land surface temperature monitoring.

Developments in Permafrost Science and Engineering in Response to Climate Warming in Circumpolar and High Mountain Regions, 2019–2024

ABSTRACTResearch in geocryology is currently principally concerned with the effects of climate change on permafrost terrain. The motivations for most of the research are (1) quantification of the anticipated net emissions of CO2 and CH4 from warming and thaw of near‐surface permafrost and (2) mitigation of effects on infrastructure of such warming and thaw. Some of the effects, such as increases in ground temperature or active‐layer thickness, have been observed for several decades. Landforms that are sensitive to creep deformation are moving more quickly as a result, and Rock Glacier Velocity is now part of the Essential Climate Variable Permafrost of the Global Climate Observing System. Other effects, for example, the occurrence of physical disturbances associated with thawing permafrost, particularly the development of thaw slumps, have noticeably increased since 2010. Still, others, such as erosion of sedimentary permafrost coasts, have accelerated. Geochemical effects in groundwater from trace elements, including contaminants, and those that issue from the release of sediment particles during mass wasting have become evident since 2020. Net release of CO2 and CH4 from thawing permafrost is anticipated within two decades and, worldwide, may reach emissions that are equivalent to a large industrial economy. The most immediate local concerns are for waste disposal pits that were constructed on the premise that permafrost would be an effective and permanent containment medium. This assumption is no longer valid at many contaminated sites. The role of ground ice in conditioning responses to changes in the thermal or hydrological regimes of permafrost has re‐emphasized the importance of regional conditions, particularly landscape history, when applying research results to practical problems.

Enhanced warming of European mountain permafrost in the early 21st century

Mountain permafrost, constituting 30% of the global permafrost area, is sensitive to climate change and strongly impacts mountain ecosystems and communities. This study examines 21st century permafrost warming in European mountains using decadal ground temperature data from sixty-four boreholes in the Alps, Scandinavia, Iceland, Sierra Nevada and Svalbard. During 2013–2022, warming rates at 10 metres depth exceed 1 °C dec−1 in cases, generally surpassing previous estimates because of accelerated warming and the use of a comprehensive data set. Substantial permafrost warming occurred at cold and ice-poor bedrock sites at high elevations and latitudes, at rates comparable to surface air temperature increase. In contrast, latent heat effects in ice-rich ground near 0 °C reduce warming rates and mask important changes of mountain permafrost substrates. The warming patterns observed are consistent across all sites, depths and time periods. For the coming decades, the propagation of permafrost warming to greater depths is largely predetermined already.

Building a Digital Twin for a Ground Heat Exchanger

AbstractThis research investigates the development of a digital twin (DT) for ground heat exchangers (GHEs) and its potential to enhance the efficiency and sustainability of shallow geothermal energy systems. It introduces an innovative approach for building a GHE‐DT that connects the physical and digital systems to monitor key parameters, predict issues, and optimize energy efficiency. The process involves several phases including implicit knowledge codification, data‐driven analysis, model construction, and system design. The study emphasizes real‐time monitoring of the effective parameters: ground temperature and fluid conditions (flow rate, temperature, and pressure). The GHE‐DT's digital system mainly comprises three sections, namely, data storage, mathematical modeling, and data‐driven modeling. The role of the presented mathematical model is to simulate the GHE's behavior and assess its performance characteristics, such as the heat exchanger's effectiveness and efficiency. Additionally, the data‐driven model used in the proposed DT utilizes formal concept analysis and relation concept analysis to identify connections and associations among parameters for a better understanding of the GHE functioning. The GHE‐DT provides useful services including trend analysis, problem prediction, and correlation analysis. These services provide engineers and operators with the opportunity to increase dependability, save maintenance costs, and optimize GHE performance.

The Effect of Ultrasonic Vibration on the 3D Printing Fabrication and Grinding Performance of Structured CBN Grinding Wheel.

The abrasives of traditional grinding wheels are usually randomly arranged on the substrate, reducing the number of effective abrasive grains involved in the machining during the grinding process. However, there are some problems such as uneven distribution of chip storage space, high grinding temperature, and easy surface burn. In trying to address this issue, an ultrasonic vibration 3D printing method is introduced to fabricate the structured CBN (Cubic Boron Nitride) grinding wheel. The effects of the fabricated process parameters, overlap rate, scanning path, and ultrasonic amplitude were analyzed. The effects of laser power, scanning speed, and powder disk rotation speed on the topography of the printing layer were analyzed by orthogonal tests. The obtained data were input into the GA-BP (Genetic Algorithm-Back Propagation) neural network for training, and the trained model was utilized to derive the optimal process parameters. Then, the experiments were carried out to optimize the overlap rate and the scanning path. The effect of ultrasonic vibration amplitude on the surface topography and the microhardness of the printing layer was observed and investigated. The structured CBN grinding wheels were fabricated using the optimal parameters, and the performance of the grinding wheels was evaluated. The workpiece surface roughness ground by the grinding wheel fabricated with ultrasonic vibration was smaller than that without ultrasonic vibration, and a better workpiece surface quality was obtained.

Stereolithography 3D printing gyroid triply periodic minimal surface vitrified bond diamond grinding wheel

The pores of vitrified bond diamond grinding wheel play a key role in the grinding process. However, uneven pore distribution and low porosity affect the grinding performance of the wheel significantly. Stereolithography based additive manufacturing provides an effective method to fabricate vitrified bond diamond grinding wheels with a uniform distribution and an interconnected pore structure. The key to high-performance grinding wheel via stereolithography 3D printing lies in the preparation of the slurry with high solid loading, low viscosity and uniform stability. In this study, the dispersion and stability of vitrified bond and diamond slurries were investigated systematically. The effects of resin monomers, surface modifiers, and solid loading on the dispersion, rheological behavior and stability of slurries were studied in detail. Finally, an optimal vitrified bond and diamond slurry for stereolithography based additive manufacturing was obtained, and complex-shaped gyroid triply periodic minimal surface grinding wheel were fabricated. By grinding the SiC ceramics, the material removal rate, grinding temperature, and surface roughness were compared to those achieved using a conventional solid structure grinding wheel. The results show that the gyroid porous grinding wheel can achieve better surface roughness and lower the grinding temperature.

Spatio-temporal variability of surface temperatures in High Arctic periglacial environment using UAV thermal imagery and in-situ measurements

ABSTRACT The rapidly changing climate in the High Arctic is posing significant challenges to its ecosystem. To better understand the changes, this study uses Uncrewed Aerial Vehicle (UAV) technology equipped with a thermal camera to investigate ground and water temperatures in the catchments of southwest Spitsbergen. This approach provides high-resolution, real-time data, offering a detailed understanding of surface temperatures in this remote and harsh environment. Integrating UAV technology with in-situ measurements enables data collection at high spatial and temporal scales, facilitating a thorough analysis of temperature trends and patterns. The research introduces a new processing workflow using open-source packages to create thermal orthomosaics, enhancing the analysis’s accuracy and efficiency. The final developed orthomosaics examine spatial variations in Land Surface Temperature (LST) and Water Surface Temperature (WST) and explore factors influencing them. Additionally, the study investigates thermal patterns in Arctic hydrological systems, such as channels and ponds, allowing for the identification and characterization of flow paths, including groundwater intrusions and surface water mixing, within the catchments. This multidimensional approach aims to provide valuable insights into the complex interactions between cryo-, hydro-, and meteorological dynamics in the High Arctic.

Pan‐Arctic Assessment of Coastal Settlements and Infrastructure Vulnerable to Coastal Erosion, Sea‐Level Rise, and Permafrost Thaw

AbstractThis study assesses the vulnerability of Arctic coastal settlements and infrastructure to coastal erosion, Sea‐Level Rise (SLR) and permafrost warming. For the first time, we characterize coastline retreat consistently along permafrost coastal settlements at the regional scale for the Northern Hemisphere. We provide a new method to automatically derive long‐term coastline change rates for permafrost coasts. In addition, we identify the total number of coastal settlements and associated infrastructure that could be threatened by marine and terrestrial changes using remote sensing techniques. We extended the Arctic Coastal Infrastructure data set (SACHI) to include road types, airstrips, and artificial water reservoirs. The analysis of coastline, Ground Temperature (GT) and Active Layer Thickness (ALT) changes from 2000 to 2020, in addition with SLR projection, allowed to identify exposed settlements and infrastructure for 2030, 2050, and 2100. We validated the SACHI‐v2, GT and ALT data sets through comparisons with in‐situ data. 60% of the detected infrastructure is built on low‐lying coast (10 m a.s.l). The results show that in 2100, 45% of all coastal settlements will be affected by SLR and 21% by coastal erosion. On average, coastal permafrost GT is increasing by 0.8°C per decade, and ALT is increasing by 6 cm per decade. In 2100, GT will become positive at 77% of the built infrastructure area. Our results highlight the circumpolar and international amplitude of the problem and emphasize the need for immediate adaptation measures to current and future environmental changes to counteract a deterioration of living conditions and ensure infrastructure sustainability.

Latitudinal gradients of biodiversity and ecosystem services in protected and non-protected oak forest areas can inform climate smart conservation

Adaptive governance of areas set aside for future protection of biodiversity, sustainable production, and recreation requires knowledge about whether and how effects of area protection are modulated by climate change and redistribution of species. To investigate this, we compare biodiversity of plants (assessed using vegetation plots) and arthropods (collected with Malaise traps, analyzed using metabarcoding) and productivity (tree growth, determined using dendrochronology) in protected and non-protected oak (Quercus spp.) forests along a latitudinal gradient (55.6 °N – 60.8 °N) in Sweden. We also compare historical, recent and projected future climate in the region. In contrast to established global latitudinal diversity gradients, species richness of plants and arthropods increased northwards, possibly reflecting recent climate-induced community redistributions, but neither was higher in protected than in non-protected areas, nor associated with contemporary ground temperature. Species composition of arthropods also did not differ between protected and non-protected areas. Arthropod biomass increased with latitude, suggesting that the magnitude of cascading effects mediated via their roles as pollinators, herbivores, and prey for other trophic levels, varies geographically and will change with a moving climate. Annual growth rate of oaks (an ecosystem service in the form of biomass increase and carbon sequestration) was independent of latitude and did not differ between protected and non-protected areas. Our findings question the efficacy of contemporary designation and management of protected oak forests, and emphasize that development and implementation of modified climate smart conservation strategies is needed to safeguard ecosystem functioning, biodiversity, and recreational values of protected forest areas against future challenges.

Structure and Changes in Thermal Fields in the Southern Group of the Kambalny Volcanic Ridge (Kamchatka) Based on Ground Temperature Surveys

Structure and Changes in Thermal Fields in the Southern Group of the Kambalny Volcanic Ridge (Kamchatka) Based on Ground Temperature Surveys

Validation of ERA5-Land-based reconstructed air temperature and near-surface ground temperature on James Ross Island

ABSTRACT This study evaluates the accuracy of ERA5-Land reanalysis products by comparing them with continuous data from James Ross Island, Antarctic Peninsula. ERA5-Land shows lower variability in air and ground temperatures than measurements from three automatic weather stations (AWSs) on James Ross Island: Johann Gregor Mendel (AWS-JGM), Abernethy Flats (AWS-AF), and Johnson Mesa (AWS-JM). Differences in mean annual air temperature (MAAT) and mean annual ground temperature at 5 cm depth (MAGT5) are noted between ERA5-Land and AWSs for the periods 2007/08-2020/21 and 2011/12-2020/21. Strong correlations (0.88–0.92) exist between ERA5-Land and AWSs, with the highest coefficients and lowest RMSE values for AWS-JM (2.7 °C for AT and 4.9 °C for GT5). Validation statistics reveal seasonal variations in ERA5-Land temperature bias with larger discrepancies in summer and low differences in winter. ERA5-Land’s snow depth estimation indicates unrealistic permanent snow cover between 3–24 meters, affecting ground temperature bias and underestimation. Despite its benefits, ERA5-Land’s inaccuracies in ground temperature data limit its direct use for permafrost research. Corrections were applied to enhance the use of ERA5-Land data for detailed permafrost studies in the JRI area.

Investigating hydrological processes using explainable deep-learning models

ABSTRACT This paper examines how meteorological factors influence streamflow. It is crucial for water resources planning and management. It develops three Deep Learning (DL) models (Long short-Term Memory (LSTM), Random Forest (RF), and Gradient Boosting Machine (GBM)) and compares their performance with multiple linear regression (MLR). LSTM is identified as the best model, and SHAP is used to analyse the contributions of different factors to streamflow. The model is applied to the Tang River catchment in China. The results indicate that: (1) DL models outperform MLR in non-linear regression; (2) the ranking of meteorological factors contributing to streamflow is: precipitation, evaporation, relative humidity, sunshine duration, ground temperature, and wind speed; (3) these factors affect streamflow within a 12-day lead time, with significant contributions closer to the prediction date; (4) during droughts, precipitation has a reduced effect on streamflow, suggesting that the streamflow is likely recharged by groundwater. The model enhances our understanding of how meteorological factors interact with streamflow dynamics.

A novel method combining strata movement and UAV infrared remote sensing technology to evaluate mining ground damage

Mining-induced ground fissures are common problems associated with mining damage in shallowly buried coal seams in the western mining area of China. To evaluate the surface mining damage of the 12203 working face of the Huojitu Colliery in Shendong mining area, low-altitude infrared aerial surveys were conducted on the ground at the static fissure area (O-A1) and the dynamic fissure area (O-A2) of the working face. The temperature evolution patterns of fissures, sand and plants in the infrared images were analysed. The relationship between overburden fractures and surface fissure temperature was revealed, and the influence range and temperature self-healing period of the surface affected by underground mining were determined. The results indicated that underground mining could lead to a decrease in the ground temperature above the working face. The surface temperature evolution can be divided into three zones: a temperature stabilization zone before mining, a temperature cooling zone during mining, and a temperature recovery zone after mining. The temperature of sand and plants above the working face exhibited quadratic curve changes in O-A1 and O-A2, respectively. The length of the temperature reduction zone affected by mining is 40 m in O-A2, and 46.8 m in O-A1. The temperature recovery periods of ground fissures in O-A1 and O-A2 were 4.0 and 4.6 d, respectively. These findings could provide a basis for evaluating mining ground damage.

The influence mechanism of thermal invasion on spontaneous combustion of different coals using continuous adiabatic heating and non-isothermal oxidation method

Within deep coal mines, the elevated ground temperature has the potential to induce thermal invasion, thereby exacerbating coal spontaneous combustion (CSC). To investigate the influence mechanism of thermal invasion on CSC, experiments were conducted using coals of different metamorphic degrees (lignite, bitumite, and anthracite) with a continuous adiabatic heating and non-isothermal oxidation method in an oxidation furnace and an in-situ ESR spectrometer. Thermal invasion markedly enhanced the inherent susceptibility of spontaneous combustion of coals by increasing the oxygen consumption rate and lowering the apparent activation energy. This enhancement results from active free radicals generated during thermal invasion which accelerated coal-oxygen reactions during non-isothermal oxidation. These free radicals were found to be mainly carbon-centred radicals adjacent to an oxygen atom (alkyl radicals). An increase in both the g-factor value and free radical concentration was observed with thermal invasion temperature and invasion duration, especially in lignite, leading to a surge of free radical concentration during non-isothermal oxidation. The active free radicals generated during thermal invasion can easily react with oxygen, providing heat for coal-oxygen reactions and enabling rapid free radical generation. These findings offer insights for developing CSC evaluation and prevention strategies in deep mines where high ground temperatures are encountered.

Fabrication of Flexible SWCNTs/Polyurethane Coatings for Efficient Electric and Thermal Management of Space Optical Remote Sensors

Given the requirement of high-efficiency thermal dissipation for large-aperture space optical remote sensors, a radiator based on single-walled carbon nanotubes (SWCNTs) filled with waterborne polyurethane (SWCNTs/WPU) coatings was proposed in this work. In situ polymerized SWCNTs/WPU coatings allowed for the uniform distribution of acid-purified SWCNTs in WPU matrix. Modified oxygen-containing groups on purified SWCNTs enhanced the interfacial compatibility of SWCNTs/WPU and enabled an improved tensile strength 9 (26.3 MPa) compared to raw-SWCNTs/WPU. A high electrical conductivity of 5.16 W/mK and thermal conductivity of 10.9 S/cm were achieved by adding 49.1 wt.% of SWCNTs. Only 2.85% and 4.2% of declined ratios for electric and thermal conductivities were presented after 1000 bending cycles, demonstrating excellent durability and flexibility. The designed radiator was composed of a heat pipe, SWCNTs/WPU coatings and an aluminum honeycomb core, allowing for −1.6~0.3 °C of temperature difference for the in-orbit temperature and thermal balance experimental temperature of the collector pipe. Moreover, the close temperature difference for the in-orbit and ground temperatures of the radiator indicated that the designed radiator with high heat dissipation met the mechanical environment requirements of a rocket launch. SWCNTs/WPU would be promising electric/thermal interface materials in the application of space optical remote sensors.