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The karst strata in the southwestern mountainous areas of China are extensively developed, creating a fragile geological environment. Landslide geological disasters occur frequently in these areas due to high annual rainfall, concentrated time periods, and frequent human engineering activities. Conventional ground geophysical methods face challenges in complex terrains, making it difficult to quickly and reliably obtain underground structures in landslide-prone areas. The semi-airborne transient electromagnetic method (SATEM) combines ground-based transmission and airborne reception of electromagnetic responses. This method, characterized by large emission magnetic moment and rapid data collection in the air, offers advantages in detecting deep geological structures in complex terrain areas. This article presents the application of a newly developed loop source SATEM system, integrated with multi-rotor unmanned aerial vehicles (UAVs), to conduct deep geological structure detection experiments on a large-scale landslide. The inversion results clearly depict the spatial distribution of the Feixianguan Formation and Longtan Formation, as well as vertical fractures developed in the strata due to underground coal mining. The detection test demonstrates the applicability of the SATEM method in detecting underground structures in Karst Plateau special landform areas, providing a new detection approach for similar regions. [ABSTRACT FROM AUTHOR]

In the controlled source audio-frequency magnetotelluric method, orthogonal electric and magnetic fields are commonly measured to determine the Cagniard apparent resistivity. However, in the near-field zone, the Cagniard resistivity is severely distorted, which is unrelated to underground structures. The Ex and Hz amplitudes in a homogeneous half-space monotonically vary in resistivity, and a numerical algorithm could achieve high-precision apparent resistivity without distortion for all frequencies. On this basis, the main focus of this investigation is on the comparative analysis of the sensitivity for the Ex field, Hz field, and Cagniard apparent resistivity to conductive and resistivity targets via synthetic models. The achieved results confirm that the Ex field could exhibit a more enhanced sensitivity for the resistive objects, whereas the Hz field could more effectively identify the conductive target. Besides, the static effect often distorts the electromagnetic data, which rigorously influences their application. The influence of the static effect on both the Ex and Hz fields is also examined in detail. The apparent resistivity based on the Ex field and Cagniard apparent resistivity is significantly affected by the static effect, which can mask deep anomalous blocks. However, the apparent resistivity based on the Hz field is almost unaffected by the static effect. Finally, a more efficient observation approach is provided for both the insulating and conductive targets. [ABSTRACT FROM AUTHOR]

The criteria on green public procurement of the European Union establish that the economic budgets of building projects must be complemented by their derived environmental and social costs. These criteria are currently being adapted to the requirements related to the circular economy, such as the use of methods to evaluate buildings environmentally. However, most methods available in the European and Spanish markets require prior training, which makes their use difficult. This paper presents an evaluation method, CEACE, for housing construction based on the determination of their footprints (ecological, carbon, and water footprints), also called the footprint family, to which the economic and social evaluation is added, as is the quantification of the construction and demolition waste generated. This method is validated with the assessment of fifteen residential buildings in Andalusia and creates an indicator that will allow technicians, companies, and administrations to evaluate projects in accordance with the criteria of green public procurement. The method is sensitive to changes in the type of building, foundation solution, and underground construction. [ABSTRACT FROM AUTHOR]

Deep excavations clearly impact adjacent existing properties and threaten their operational safety. Predicting the deformation of existing infrastructure induced by nearby underground construction is the main concern of urban underground development. This paper presents an analytical calculation method for predicting underground pipe gallery deformations induced by adjacent deep excavations. First, the authors assume the existing pipe gallery to be nonexistent in the soil and propose a solution to calculate the excavation-induced vertical movements of the soil at the position of the existing pipe gallery. Thereafter, the authors simplify the existing pipe gallery as an elastic beam on a Winkler foundation to calculate its deformation. Finally, the method is verified by the good agreement found between the calculated result and the field measurement of the construction of the Shanghai Hongqiao CBD project. The proposed analytical method of this work can provide accurate evaluation results for similar engineering projects. [ABSTRACT FROM AUTHOR]

Because they are in enclosed underground buildings, the generator layers of hydropower stations have limited ventilation. In order to reduce the influence of a hot and humid environment on equipment and staff health and create a good thermal environment with good air quality for underground buildings, in this paper, vertical wall-attached ventilation was combined with the generator layer of a hydropower station to replace traditional ventilation. The influence of air supply velocity, air supply outlet position, and the opening mode of the generator layer on indoor velocity and temperature field distribution were analyzed via numerical simulation, and the evaluation indices of different cases were also compared. In the single-sided vertical wall-attached ventilation mode, when the velocity was increased from 4 m/s to 8 m/s, the maximum increment in the energy utilization coefficient was 41%, and the maximum reduction in the velocity non-uniformity coefficient was 9.5%. The results show that the single-sided mode can offer a higher ventilation efficiency than the double-sided mode, with a higher energy efficiency and a more uniform air distribution. Based on the mean temperature and velocity, and the key evaluation indices (head-foot temperature difference, percentage of dissatisfaction, non-uniformity coefficient, energy utilization coefficient, and air diffusion performance index), it is suggested that the single-sided air supply mode should be adopted for this kind of tall building, with an air supply velocity of v = 6 m/s and two open air supply outlets at each interval. [ABSTRACT FROM AUTHOR]

This paper investigates a method for improving the selection of seismic motions for designing earthquake-resistant underground structures. It is found that PGV alone is unreliable as a predictor of structural damage with increasing earthquake intensity. Therefore, based on characterizing seismic intensity by using PGV, another parameter, referred to here as "the severest parameter", is introduced to distinguish potential damage capacity for different seismic motions. A numerical model of a soil–underground structure system was established using the finite element software OpenSees. A total of 120 real ground motions were selected for the model, considering the influences of eight different site groups on the underground station and the rupture distances of the input seismic motions. The results show that as seismic intensity increases, substantial variability in the response of underground structures emerges under the same amplitude of PGV, diminishing the effectiveness of the relationship between PGV and structural damage. When assessing the potential damage capacity of seismic motions with similar or close amplitudes of PGV, VSI is an appropriate severest parameter for Class III sites and ASI is suitable for Class II sites. When the correlation coefficient between the severest parameter and the structural response is greater than 0.8, it can be used to reliably assess seismic damage capacity based on the size of the severest parameter. [ABSTRACT FROM AUTHOR]

During the construction of underground engineering, the prediction of groundwater distribution and rock body permeability is essential for evaluating the safety of the project and guiding subsequent design and construction. This article proposes an objective function that solves an underdetermined inverse analysis problem based on the least-squares theory and regularization method and uses geostatistics theory and the variogram function to describe the spatial characteristics of the actual engineering system. It also establishes an optimization model of the analysis stratum seepage field and puts forward the method of using on-site test observation data to solve the stratum penetration coefficient. Relying on the foundation pit project of the Lingshanwei Station of Qingdao Metro, the on-site pumping and packer permeability test was conducted for different strata venues in the foundation pit, and the on-site water-head observation value was obtained. Physical detection of the influence area of foundation pit excavation confirms the correctness of the model from the region and verifies the accuracy of the model on the value through the on-site pumping test. Results show that the accuracy of the use of this objective function to solve the underdetermined inverse problem is above 85%, which proves the effectiveness of the method. The stratigraphic geological information obtained by the inverse analysis model provides an important basis for engineering design and security construction. [ABSTRACT FROM AUTHOR]

This paper presents the design and commissioning of a novel pseudo‐static test apparatus for underground structures that accounts for soil‐structure interaction by simulating the soil with suitably designed springs. The developed apparatus was employed to conduct 1:10 large scale tests on a two‐story three‐span prefabricated subway station structure. Two comparative cyclic load tests were conducted: one involved the developed springs‐structure system; and one involved the structure alone (no springs). The test results demonstrated important differences in the damage location, damage degree, bearing capacity, and deformation capacity of the prefabricated subway station structure under the two loading conditions (i.e., with and without springs). The presence of springs (i.e., soil‐structure interaction) enhanced the lateral collapse resistance of the underground structure and affected the inter‐story displacement ratio (IDR) between the upper and lower layers of the two‐story prefabricated subway station structure. However, it did not affect the deformation coordination of the walls and columns of each layer. A finite element model of the prototype station was also established to conduct dynamic time history analysis simulating the soil‐structure interaction. The results from the dynamic analysis validated the effectiveness of the pseudo‐static test method employing the spring‐structure system. The excellent agreement between the calculated dynamic responses and the responses obtained from the pseudo static tests confirmed the ability of the developed apparatus to conduct seismic tests on complex large‐scale underground structures such as prefabricated subway stations. Thus, this test methodology might be utilized to attain valuable insights into the seismic performance of prefabricated subway stations at a relatively low cost and effort. [ABSTRACT FROM AUTHOR]

Relying on geological data to construct 3D models can provide a more intuitive and easily comprehensible spatial perspective. This process aids in exploring underground spatial structures and geological evolutionary processes, providing essential data and assistance for the exploration of geological resources, energy development, engineering decision-making, and various other applications. As one of the methods for 3D geological modeling, multipoint statistics can effectively describe and reconstruct the intricate geometric shapes of nonlinear geological bodies. However, existing multipoint statistics algorithms still face challenges in efficiently extracting and reconstructing the global spatial distribution characteristics of geological objects. Moreover, they lack a data-driven modeling framework that integrates diverse sources of heterogeneous data. This research introduces a novel approach that combines multipoint statistics with multimodal deep artificial neural networks and constructs the 3D crustal P-wave velocity structure model of the South China Sea by using 44 OBS forward profiles, gravity anomalies, magnetic anomalies and topographic relief data. The experimental results demonstrate that the new approach surpasses multipoint statistics and Kriging interpolation methods, and can generate a more accurate 3D geological model through the integration of multiple geophysical data. Furthermore, the reliability of the 3D crustal P-wave velocity structure model, established using the novel method, was corroborated through visual and statistical analyses. This model intuitively delineates the spatial distribution characteristics of the crustal velocity structure in the South China Sea, thereby offering a foundational data basis for researchers to gain a more comprehensive understanding of the geological evolution process within this region. [ABSTRACT FROM AUTHOR]

Solar photovoltaic (PV) power generation is a major carbon reduction technology that is rapidly developing worldwide. However, the impact of PV plant construction on subsurface microecosystems is currently understudied. We conducted a systematic investigation into the effects of small-scale light stress caused by shading of PV panels and sampling depth on the composition, diversity, survival strategy, and key driving factors of soil bacterial communities (SBCs) under two vegetation restoration modes, i.e., Euryops pectinatus (EP) and Loropetalum chinense var. rubrum (LC). The study revealed that light stress had a greater impact on rare species with relative abundances below 0.01% than on high-abundance species, regardless of the vegetation restoration pattern. Additionally, PV shadowing increased SBCs' biomass by 20-30% but had varying negative effects on the numbers of Operational Taxonomic Unit (OTU), Shannon diversity, abundance-based coverage estimator (ACE), and Chao1 richness index. Co-occurrence and correlation network analysis revealed that symbiotic relationships dominated the key SBCs in the LC sample plots, with Chloroflexi and Actinobacteriota being the most ecologically important. In contrast, competitive relationships were significantly increased in the EP sample plots, with Actinobacteriota having the most ecological importance. In the EP sample plot, SBCs were found to be more tightly linked and had more stable ecological networks. This suggests that EP is more conducive to the stability and health of underground ecosystems in vulnerable areas when compared with LC. These findings offer new insights into the effects of small-scale light stress on subsurface microorganisms under different vegetation restoration patterns. Moreover, they may provide a reference for optimizing ecological restoration patterns in fragile areas. [ABSTRACT FROM AUTHOR]

Columnar jointed basalt (CJB) is a kind of jointed rock with a polygonal cylinder mosaic structure that has complex mechanical properties such as discontinuity and heterogeneity. The typical geological structure of the CJB is the intercolumnar joint plane and the implicit joint plane, which obviously affect the mechanical properties of the rock mass. Controlling the unloading relaxation of the CJB is a key problem during the construction of underground engineering. In this paper, in-situ acoustic wave and panoramic borehole camera measurements were carried out in the cavern of the Baihetan project to understand the failure mechanism of the collapse of the CJB. It was quite clear that the evolution of the excavation damage zone (EDZ) of the CJB depends on the time and spatial effects. The closer to the collapse zone, the greater the degree of relaxation failure of the columnar joint rock mass; the further away from the cavern perimeter, the more stable the surrounding rock. The correction between wave velocity and cracks in the rock mass was also discussed. This field test and theoretical analysis can provide a reference for studying the failure mechanism and control measures of CJB in underground caverns under high geostress. [ABSTRACT FROM AUTHOR]

The Gran Sasso National Laboratory (LNGS) is, at present, the largest deep underground laboratory in operation for astroparticle physics and rare event research. The LNGS was created to carry out this research exploiting an overburden of 1,400 m of rock to reduce the flux of muons from cosmic rays. Operating an underground laboratory and its facilities implies a high level of risk. To mitigate risks at the LNGS, a crucial aspect is represented by the evacuation of people from an underground environment during emergencies. The connection between the underground facilities and the outside infrastructure is limited, and the intervention by rescue teams is complicated. This paper reports the study of an adaptive evacuation system to improve the evacuation performance in underground laboratories. The system proposed is composed of a combination of passive, dynamic, and adaptive signage that is able to adapt itself to lead the laboratory occupants to the safe location for evacuation (assembly point). The system collects information from all safety plants, and the data are processed using a customized path-finding algorithm. In the computational algorithm, the underground laboratory is represented as a grid, and the customized path-finding algorithm discovers all available paths to reach the identified evacuation assembly point. [ABSTRACT FROM AUTHOR]

The crack initiation stress threshold is widely used in excavation industries as rock spalling strength when designing deep underground structures to avoid unwanted brittle failures. While various strain-based methods have been developed for the estimation of this critical design parameter, such methods are destructive and often requires subjective interpretations of the stress–strain curves, particularly in rocks with pre-existing microcracks or high porosity. This study explore the applicability of non-destructive ultrasonic through-transmission methods for determining rock damage levels by assessing the changes in transmitted signal characteristics during loading. The change in velocity, amplitude, dominant frequency, and root-mean-square voltage are investigated with four different rock types including marble, sandstone, granite, and basalt under various stress levels. Results suggest the rate of signal variations can be reliably used to estimate crack closure and crack initiation stress levels across the tested rocks before failure. Comparison of the results between the conventional techniques and the new proposed methods based on ultrasonic monitoring are further discussed. [ABSTRACT FROM AUTHOR]

Rock and soil masses in geotechnical engineering projects, such as tunnels, mines and slopes, undergo relative motion, exhibiting mechanical characteristics of solid–fluid transition under critical conditions. This work analyzes the characteristics of the solid–fluid transition interface and the mode of load transfer through biaxial compression particle flow photoelastic experiments on granular materials. The study documents that this interface forms an arch shape, marked by a force chain arch. The granular material exhibits two distinct states depending on its position: below the arch, the granular material is in a solid–fluid transitional state, with bearing capacity reduced, while above the arch, it is in a stable solid state, capable of bearing the overlying rock layer's load. The presence of the force chain arch alters the direction of the originally downward-transferring load, redirecting it along the trajectory of the arch. Analysis of the force and stability of the force chain arch revealed that the arch shape parameters and boundary loads control the instability of the arch. Changes in the overlying and lateral loads lead to different types of instability of the force chain arch. The findings of the study are crucial for underground engineering construction and for the prevention of geological disasters related to granular material. [ABSTRACT FROM AUTHOR]

The Winkler foundation modulus is key to evaluating the response of underground structures using the elastic foundation beam model. In this paper, an improved formula of the Winkler foundation modulus for a beam embedded in a full space is proposed to overcome the limitation of inconsistent assumptions in previous studies. To achieve this goal, the bending responses of the beam are obtained using the elastic foundation beam model and three-dimensional elastic continuum model, respectively, wherein a consistent assumption is proposed that tangential interactions at the beam–ground interface are ignored in the two models. In addition, as deformation of the site is an important source of the underground structure response, the beam is applied to standard soil displacement of the free field on the Winkler foundation to improve the accuracy of the Winkler modulus obtained by fitting solutions based on the concentrated force on the beam. The formula for the Winkler foundation is obtained by equating the first zero of the bending moment in the two models. The Winkler foundation modulus is verified by comparing the results with numerical solutions and previous studies. [ABSTRACT FROM AUTHOR]

High-resolution three-dimensional VP, VS and VP/VS images in the Houziyan Reservoir Area were obtained by using Fast Marching Tomography Package (FMTOMO) with the travel time data from 6330 seismic events monitored by the Houziyan Reservoir Seismic Network. This analysis yielded the 3-D velocity structure, including longitudinal wave velocity (VP), shear wave velocity (VS), and the ratio of longitudinal and shear wave velocity (VP/VS) at different impoundment stages. The data changes at various impoundment times, depths of sections, and directions of profiles were analyzed to obtain these results. The final findings demonstrate the following results: 1) Through tomographic analysis, it was determined that the underground velocity structure in the Houziyan reservoir area was anisotropic before impoundment. 2) The area of high wave velocity increases in stage 1, stage 3, and stage 4. The area of low wave velocity increases in stage 2, especially in depth, indicating significant changes in the underground velocity structure at different impoundment stages. 3) Compared to the changes in underground velocity structures in other reservoirs after impoundment, the Houziyan reservoir exhibited a unique pattern. 4) In general, the underground velocity structure displayed an overall increasing trend after impoundment. However, it also exhibited instances of decreasing velocity, reflecting continuous dynamic adjustments to the underground velocity structure after impoundment. These conclusions highlight the impact of impoundment in the reservoir area on the underground velocity structure and provide scientific theoretical support for seismic risk assessment following impoundment in the reservoir area. [ABSTRACT FROM AUTHOR]

The results of the experimental study of the degradation of steel structures of sewer underground constructions are presented. The distribution of harmful gas elements (sulfur, hydrogen, oxygen) over the wall thickness of sewer pipes along corrosion defects in the form of pits, as well as the character of changes in the microhardness of the metal depending on the hydrogen content and service life, are shown. To confirm the metal softening with increasing hydrogen concentration, the stresses of the crystal lattice (distortion stresses) were measured. [ABSTRACT FROM AUTHOR]

Compressive stress generated at collision fronts can propagate over long distances, inducing deformation within the continent's interior. Nevertheless, the factors governing the partitioning of intracontinental deformation remain enigmatic. The Altai Mountains serve as a type‐example of ongoing intracontinental deformation. Here, we investigate the crustal architecture of the Chinese Altai Mountains, using receiver functions obtained from newly deployed dense seismic nodal arrays. The new seismic results reveal distinct crustal features, including (a) a negative polarity discontinuity beneath Chinese Altai Mountains, suggesting a low‐velocity layer; (b) a north‐dipping mid‐crustal structure beneath the suture zone between East Junggar and Chinese Altai, indicating underthrusting of East Junggar's lower crust beneath the Chinese Altai Mountains; (c) a double Moho structure beneath East Junggar, revealing a high‐velocity lower crustal layer. In conjunction with constraints from previous multi‐disciplinary regional studies, the double Moho structures are interpreted as mafic restite from Late Paleozoic magma underplating. The addition of mafic materials can significantly enhance the rheological strength of East Junggar's crust, causing it to function as an indenter that thrust beneath the Chinese Altai Mountains during the subsequent convergence process. As a consequence, significant deformation occurs in the Chinese Altai region, resulting in the emergence of decollements, as evident by the negative polarity discontinuity. The presence of pre‐existing decollements makes the Altai Mountains region more susceptible to deformation, thereby facilitating the concentration of intracontinental deformation. These findings illuminate the evolution history of the Chinese Altai Mountains and highlight the great impacts of ancient tectonics on intracontinental deformation partitioning. Plain Language Summary: The factors that control how deformation is distributed within mountains located within continents are still not fully understood. In this study, we focused on the Altai Mountains to bring clarity to this topic. We used a new kind of seismic data to create images of the underground structures in the East Junggar‐Altai area. By combining information from previous studies in the region, we built a picture of how this area has changed since the Late Paleozoic era. During the Late Paleozoic period, the East Junggar region's crust became stronger due to a process involving molten rock moving upward and hardening beneath it. As a result, it was pushed below the Altai Mountains in a convergence event. This convergence caused extensive changes in the Altai Mountains' crust, creating a weakened section near the surface. The crustal properties and structures formed from ancient tectonic activities during the Paleozoic era have been preserved over time. This has made the Altai Mountains particularly prone to experiencing more recent deformations within the continent. Our findings emphasize how important ancient tectonic events are in determining how deformation is spread within continents. Key Points: High‐resolution images of crustal structures of the East Junggar‐Altai area were obtained from newly deployed dense seismic arraysNew constraints have emerged in the evolutionary history of the Chinese Altai‐East Junggar regions since the Late PaleozoicInherited crustal structures and properties arose from the Paleozoic tectonics govern the partitioning of the intracontinental deformation [ABSTRACT FROM AUTHOR]

Fault reactivations induced by deep excavation can pose significant challenges to underground construction or resource extraction. Laboratory experiments on rock faults demonstrate that unloading‐induced fault reactivations obey the Coulomb failure criterion derived from loading‐induced events. However, the effect of stress path during unloading on the failure criterion and rupture dynamics of fault reactivations remains poorly understood. Here, we present findings from a series of laboratory experiments aimed at elucidating the effect of the unloading path on the failure criterion and rupture dynamics of fault reactivations. We conducted experiments under various stress conditions, examining two cases of unloading paths. In Case I, we unloaded the minimum principal stress, while in Case II, the maximum principal stress was unloaded. Strain gauges and high‐speed photography were employed to capture the transient dynamic rupture process. Our investigations have yielded new insights into the effect of unloading path on the rupture dynamics when the fault is reactivated. In Case I, we observed fault reactivations resembling those loading‐induced events characterized by forward sliding. Conversely, in Case II, fault reactivations associated with stress reversal produce mild reversed sliding with lower stress drop and rupture velocity. Furthermore, we find that there is a remarkable reduction in static friction for reversed sliding, indicating that the failure criterion for fault reactivation is influenced by the stress path. We demonstrate that enhanced stress heterogeneity, caused by stress reversal, serves as a mechanism for reduced static friction. These findings contribute to our understanding of the mechanisms underlying fault reactivations, particularly those involving reversed sliding. Plain Language Summary: It is known that underground excavation, accompanied by stress release, can trigger fault reactivation, resulting in induced earthquakes. Understanding how unloading affects the activation and rupture dynamics of these induced events is crucial. To investigate the role of unloading path, we conducted laboratory experiments to simulate unloading‐induced fault reactivation on analog material containing a fault. Loadings are applied biaxially at the boundary. We observed that unloading the minimum principal stress (i.e., reducing the minimum loading) could reactivate the fault, generating forward sliding resembling loading‐induced rupture events. Conversely, unloading the maximum principal stress (i.e., reducing the maximum loading) induces reversed sliding, featuring smaller stress drop, coseismic slip, and rupture speed compared to forward sliding. Moreover, the static friction coefficient is reduced prior to reversed sliding. We also found that enhanced stress heterogeneity prior to unloading‐induced reversed sliding can account for the difference in static friction coefficient. Therefore, it is necessary to incorporate the effect of loading path into the studies of fault reactivation. Key Points: Rupture process of unloading‐induced fault reactivation is dictated by the initial stress state and stress pathThe static friction of fault is reduced for the unloading‐induced reversed slidingEnhanced stress heterogeneity caused by stress reversal contributes to reduced static friction [ABSTRACT FROM AUTHOR]

Ophiolite zones in Iran are capable of bearing precious minerals, which indicates the importance of undertaking investigations into ophiolite belts. Although the northeastern ophiolites of Iran cover a vast area, they should be better recognised in terms of geophysical features and properties. The Sabzevar ophiolite area is an orogenic and subducted zone with typical ophiolite series, including sedimentary, crustal and mantle sequences. This study sets out to characterise the auspicious igneous and ophiolite zones in the frame of large-scale and tectonic conditions, geometrical shapes, expansions, and deep susceptibility features through novel magnetic synthesis interpretation techniques. In order to study the mentioned area, airborne magnetometry data over 60,000 km2 have been utilised. Thus, geophysical research has been conducted to define the tectonic and ophiolite zones of the Sabzevar area by means of magnetic methods including edge detection techniques and 3D susceptibility models. In this research, newly developed edge-detection filters of MNTHD and MNTDR are applied to the aeromagnetic data to identify the shape and boundary of the anomalies at the Sabzevar ophiolite. In addition, edge detection would facilitate dividing the study area into smaller sectors, as proper targets, for running 3D inversion schemes precisely. This study uses qualitative analysis to gain insights into the subsurface structure status. The simultaneous interpretation of edge detection results and 3D inverted models would lead the way to dependable outcomes. The study area consists of six ophiolite sections, pre-identified by geological and geochemical approaches. These are the basis for this research which primarily studies the Sabzevar ophiolitic area. In order to conduct a detailed investigation into the study area, seven blocks were considered for the inverse modelling procedure. Consequently, the 3D susceptibility models matched the edge detection results accurately. Finally, as a multidisciplinary geophysical investigation over a large-scale ophiolite belt, the inverted susceptibility models of the whole area were overlaid with the geological and magnetic edge detection maps, unifying a solid view of the deep underground structures. [ABSTRACT FROM AUTHOR]

Water inrush has become one of the main engineering hazards in tunnel and underground engineering construction. A new ideal point interval recognition model for risk assessment of water inrush was proposed to accurately predict and effectively prevent the hazard. Given the complexity and uncertainty of the geological conditions of tunnel engineering, a continuous interval of a small range was used to assign the evaluation index instead of a fixed value. The positive and negative ideal points and the ideal distance measure function were improved. The fusion method of multi-index ideal distance measure interval and the risk classification standard based on ideal closeness degree was presented. The integrated weighting method combining the analytic hierarchy process (AHP) and frequency statistic method was introduced to determine the weight of the evaluation index. The AHP was improved based on the proposed 1~5 scale and triangular fuzzy theory. Considering the dynamic risk change of water inrush, a dynamic risk assessment method was established to realize the process control of the hazard including the preliminary assessment and secondary assessment. The risk-pregnant environment factors were selected to evaluate the preliminary risk before tunnel construction. In the construction of the tunnels, the environmental factors were modified and the risk-causing factors were introduced to evaluate the secondary risk. The proposed method was used to dynamically evaluate the risk of water inrush in the river-crossing section of the Yuelongmen Tunnel from Chengdu to Lanzhou Railway. The evaluation results were in good agreement with the actual situation. The method has better grade discrimination and risk identification and has a certain guiding significance for risk prevention and control of tunnel and underground engineering geological hazards. [ABSTRACT FROM AUTHOR]

Most recent tunnel designs rely on more thorough analyses of the intricate rock interactions. The three principal techniques for excavating rock tunneling are drill-and-blast for complete or partial cross-sections, TBM only for circular cross-sections with full faces, and road header for small portions. Tunnel-boring machines (TBM) are being utilized to excavate an increasing number of tunnels. Newer studies have demonstrated that subterranean structures such as tunnels produce a variety of consequences during and after ground shaking, challenging the long-held belief that they are among the most earthquake-resistant structures. Consequently, engineering assessment has become crucial for these unique structures from both the geotechnical and structural engineering standpoints. The designer should evaluate the underground structure's safety to ensure it can sustain various applied loads, considering both seismic loads and temporary and permanent static loads. This paper investigates how adding elastic, soft material between a circular tunnel and the surrounding rock affects seismic response. To conduct the study, Midas/GTS-NX was used to model the TBM tunnel and the nearby rock using the finite element (F.E.) method to simulate the soil–tunnel interactions. A time–history analysis of the El Centro (1940) earthquake was used to calculated the stresses accumulated in the tunnels during seismic episodes. Peak ground accelerations of 0.10–0.30 g, relative to the tunnel axis, were used for excitation. The analysis utilized a time step of 0.02 s, and the duration of the seismic event was set at 10 s. Numerical models were developed to represent tunnels passing through rock, with the traditional grout pea gravel vs. isolation layer. A parametric study determined how isolation material characteristics like shear modulus, Poisson's ratio, and unit weight affect tunnel-induced stresses. In the meantime, this paper details the effects of various seismic isolation materials, such as geofoam, foam concrete, and silicon-based isolation material, to improve protection against seismic shaking. The analysis's findings are discussed, and how seismic isolation affects these important structures' performance and safety requirements is explained. [ABSTRACT FROM AUTHOR]

Anomaly detection of internal defects in underground engineering structures is critical. This paper proposes an unsupervised deep learning image-to-image translation method tailored for ground penetrating radar (GPR) images. The proposed model can translate real-world GPR images to simulated ones. In this manner, labeling real GPR images is not necessary, and only the target detection model trained on simulated GPR images is required to directly identify defects in real GPR images. The unsupervised deep learning network introduces geometry-consistency constraints into the CycleGAN, which largely prevents the problem of semantic distortion in translation. Validation of the proposed method was performed using GPR data collected in various scenarios using GPR of different center frequencies and manufacturers. Moreover, to verify its adaptability and feasibility for defect recognition, commonly used deep learning-based defect recognition methods, which were trained only on simulated GPR images, were used to detect the translated GPR images. The findings indicate that the type and location of internal defects in translated GPR images can be accurately identified using the proposed method. [ABSTRACT FROM AUTHOR]

In the Republic of Korea, large-scale deep excavation construction is being conducted adjacent to structures owing to overpopulation in urban areas. Securing the safety of earth-retaining and underground structures is crucial for adjacent excavation work in urban areas. Accordingly, an automated measurement system is used to monitor the behaviors of subway tunnels and track structures; however, the utilization of its results is extremely low. Existing techniques evaluate the safety of track and tunnel structures based on the measured maximum values. This study introduces an evaluation technique for improving behavior monitoring in subway tunnels and track structures. A substantial amount of long-term measurement data on subway tunnels and track deformation was quantitatively evaluated using the Gaussian probability density function. In addition, the results from the same location where the tunnel convergence meter (TL) and track bed settlement (RM) sensors were located were compared. The comparison results revealed a difference in the vertical displacement of the tunnel and track structure owing to adjacent excavation work. A technique to analyze the continuous behavior of the tunnel was presented by numerically analyzing the tunnel measurement results as input data. In addition, they emphasized the need for simultaneous monitoring of tracks and tunnels. [ABSTRACT FROM AUTHOR]

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Accurate prediction of the future mechanical behaviour of the underground structure is important for the traffic system. However, the existing works mostly just predicted one type of property and failed to study the influence of different properties in the tunnel. Besides, most of them predicted future behaviours without considering the external influence of the environment like temperature and water pressure. In this paper, we propose a multi-task prediction model named MSTNet which combines different types of indicators and external factors for capturing the temporal and spatial characteristics in the tunnel. Firstly, we integrate time series of multiple indicators and build a deep learning algorithm based on a graph neural network and recurrent network to capture the temporal, spatial and external impacts in the tunnel. Then, we have a case study on the Wuhan Yangtze River tunnel which contains the comparison of different components in our model, the compared results between the single indicator and multiple indicators and the performance analysis among traditional models. From the experiment results, we could find that the ability of the MSTNet model is superior to other methods, whose capability achieved over 93% and 94% in strain variation and joint opening sensors on Pearson Correlation Coefficient (PCC) in the next 45 days, respectively. [ABSTRACT FROM AUTHOR]

Underground structures such as tunnels, powerhouse caverns and subway stations, as a main structure, have different side structures that are considered for utility and access. Side structures have usually been constructed adjacent to the main structure in the form of gallery and shaft. The study focuses on the influence of construction of a nearby link tunnel between line 6 and 7 of Tehran metro in Iran, as a side structure, on existing F6G7 exchange subway station as a main structure using 3D numerical model, analytical and observational method. When a structural element is deformed, the internal forces are induced within it, therefore the host ground deformation due to adjacent excavation is known as a controlling factor to ensure the structural adequacy of existed underground structure. This goal will not be achieved unless the adjacent structure construction process is selected with proper staged construction and accepted ground deformation. Eight different schemes for excavation of link tunnel adjacent to F6 station were evaluated. The state of stress surrounding non-circular link tunnel, induced internal forces and structural design of F6 station were assessed based on eight construction schemes for link tunnel. The results show that partial excavation, using invert in initial support system, using pre-supporting system in link tunnel staged construction process have significant effect to reduce the host ground deformation and structural responses of F6 subway station consequently. [ABSTRACT FROM AUTHOR]

Application of Artificial Intelligence (AI) in tunnel construction has the potential to transform the industry by improving efficiency, safety, and cost-effectiveness. This paper presents a comprehensive literature review and analysis of hotspots and frontier topics in artificial intelligence-related research in tunnel construction. A total of 554 articles published between 2011 and 2023 were collected from the Web of Science (WOS) core collection database and analyzed using CiteSpace software. The analysis identified three main study areas: Tunnel Boring Machine (TBM) performance, construction optimization, and rock and soil mechanics. The review highlights the advancements made in each area, focusing on design and operation, performance prediction models, and fault detection in TBM performance; computer vision and image processing, neural network algorithms, and optimization and decision-making in construction optimization; and geo-properties and behaviours, tunnel stability and excavation, and risk assessment and safety management in rock and soil mechanics. The paper concludes by discussing future research directions, emphasizing the integration of AI with other advanced technologies, realtime decision-making systems, and the management of environmental impacts in tunnel construction. This comprehensive review provides valuable insights into the current state of AI research in tunnel engineering and serves as a reference for future studies in this rapidly evolving field. [ABSTRACT FROM AUTHOR]

With the progress of technology and the development of society, the construction demand for underground large-diameter vertical engineering is increasing. It has extended from the traditional underground mining field to various fields such as hydroelectric power generation, highway and railway tunnels, civil defense engineering, military engineering, municipal engineering, etc. For a long time, the construction of underground large-diameter vertical engineering in China has mainly relied on manual and semi mechanized methods, with high safety risks, high labor intensity, and low work efficiency. If large-diameter Raise Boring Machine are used for construction, the high cost of one-time investment restricts the mechanization of large-diameter vertical engineering construction. This article provides a detailed introduction to the structural composition, working principle, and construction technology of the stepper cutter head. The hydraulic system is analyzed, and the reset time of the cylinder under different pre filled nitrogen pressure conditions is tested. A remote communication control system solution for complex conditions in underground mines is proposed, and this technology is applied to actual production in mines. The results show that the stepper cutter head can achieve the construction of large shafts using a small Raise Boring Machine, the mechanization of large-diameter vertical engineering construction in China s underground small and medium-sized mines and other fields is of great significance. [ABSTRACT FROM AUTHOR]

Purpose: This article concentrates on the block-hierarchical structures of rock masses and investigates the dynamic problem and dispersion relation of pendulum-type waves caused by the low-frequency vibrations of rock blocks in blocky rock masses, and determines the effect of block-hierarchical structures. Methods: The blocky rock masses composed of granite blocks and rubber interlayers are simplified into the block–spring model and the wave motion model. Based on Bloch theorem and d'Alembert's principle, the dispersion relation and equations of motion of blocky rock masses with complex block-hierarchical structures are determined, respectively. Conclusion: With the increase of the rock size and geomechanical invariant, the initial frequency of the first attenuation zone gradually decreases, and only the low-frequency waves lower than that frequency can propagate in the blocky rock masses, which reveals the mechanism of low-frequency characteristics of pendulum-type waves theoretically. Research on the two models with different block-hierarchical structures indicates that the equivalent substitution of the two models is not universal and unconditional. The larger the stiffness ratio, or the higher the order of block-hierarchical structures, the smaller is the effect of ignoring the high-order hierarchical structures. Applications: The research will be of interest to a wide range of experts in the fields of stress wave propagation, earthquake engineering and rock bursts, as well as those working to reduce the engineering vibrations of underground structures and process monitored wave packet data for structures. [ABSTRACT FROM AUTHOR]

The growth of cities induced an increased demand for infrastructure including tunnel constructions. Because the urban ground usually is soft soil therefore tunnel constructions may cause ground settlement and damage the structures around. So, it is very important to carefully consider the tunnel construction effect on the design, construction, operation, and risk assessment of structures around the tunnel. In this paper, the finite element method was used to study the influence of the tunnel excavation on beneath piled buildings at the Hanoi metro line 03. These results indicate that the internal forces and displacements of the pile are greatest for the front pile closest to the tunnel in the group, which is the first pile to be loaded in the group. Two parameters: the tunnel burial depth and the distance from the tunnel centreline to the beneath-piled building have been investigated. These results found that the distance from the tunnel axis to the beneath piled building increases, while both the internal forces and displacements of the pile decrease. These internal forces and displacements increase with greater tunnel burial depth. The magnitude of normal forces and bending moments in the tunnel lining increase as the tunnel burial depth increases, while normal forces increase and bending moments in the tunnel lining decrease when the distance from the tunnel axis to the beneath-piled building decreases.

This document is an editorial from the journal Frontiers in Earth Science, discussing the instability mechanism and disaster prevention of jointed rock masses. The presence of joints and discontinuities in rock masses can lead to instability and pose risks to engineering structures. The editorial highlights the progress made in this field, including studies on the mechanical properties of rock samples, failure characteristics of stratified and fractured rock masses, blasting vibration propagation in tunnels, and the evolution process of tunnel instability. The editorial also provides a list of papers published on this research topic for further exploration. [Extracted from the article]

The underground space development is associated with the emergence of complex and dangerous situations, often leading to accidents. The condition for their development is the potential geotechnical risks. High-quality execution and analysis of design work at all the stages of design, starting from the early stages, is one of the effective ways to control risks. Clarification of the characteristics and features of the rock mass adjacent to the projected underground structure makes it possible to identify the potential cause of the occurrence of an adverse event with a certain probability during the construction and operation of an underground structure. The purpose of a qualitative risk analysis is to identify risk factors in underground construction. The value of the total geotechnical risk, expressed by the sum of each of the possible risks, should be numerically estimated at the design stage of a specific underground facility. At the same time, it is extremely important to develop a methodology for managing geotechnical risks, which would make it possible to assess their probability of development at an early stage of project preparation and propose measures to reduce or prevent them. This technique is given in the article. The results of the study conducted in accordance with the presented methodology showed that geotechnical risk control proved an effective method in preventing accidents during underground construction.

The inversion of gravity and magnetic data can obtain the density and magnetic structure of underground space, which provide important information for resource exploration and geological structure division. The most commonly used inversion method is smooth inversion in which the objective function is built with L2-norm, which has good stability, but it produces non-focused results that make subsequent interpretation difficult. The power-type structural self-constrained inversion (PTSS) method with L2-norm is proposed to improve the resolution of smooth inversion. A self-constraint term based on the power gradient of the results is introduced, which takes advantage of the structural feature that the power gradient can better focus on the model boundary to improve the resolution. For the joint inversion of gravity and magnetic data, the power-type mutual-constrained term between different physical structures and the self-constrained term can be simultaneously used to obtain higher-resolution results. The modeling tests demonstrated that the PTSS method can produce converged high-resolution results with good noise immunity in both the respective inversions and the joint inversion. Then, the PTSS joint inversion was applied to the airborne gravity and magnetic data of the iron ore district in Shandong, revealing the shape and location of the mineralized rock mass, which are crucial information for subsequent detailed exploration. [ABSTRACT FROM AUTHOR]

The U-steel support structures of underground caverns are prone to instability and failure under blast loads. The purpose of the underground cavern reinforcement is to mobilise the self-supporting capacity of the surrounding rock to resist the blast. To better understand the mechanical performance and failure mechanism of the U-steel support, the fracture process and vibration behaviour of the support structure under blast loading are investigated by the microseismic monitoring experiment. The dynamic responses of the cavern support structures under blast loading are investigated, and the potentially hazardous sections of the U-steel support structure are revealed by the theoretical analysis. The microseismic monitoring results show that the blast induced microseismic events are concentrated in the arch shoulder of the small chaînage, correspondingly the U-steel structures in this region have been partially extruded and deformed. The failure mechanism of the supporting structure is presented. In order to effectively inhibit the internal fracture evolution or macroscopic failure of the rock mass, the synergetic reinforcement scheme of the structures is proposed. The results of the research can be used as a reference for the design and control method of the U-steel support in similar projects. [ABSTRACT FROM AUTHOR]

Pipe jacking is a trenchless construction method to achieve forward tunneling and efficient construction of underground structure simultaneously without extensive surface excavation. In the process of pipe jacking construction, the jacking force provided by the hydraulic jacking equipment must overcome the frontal resistance of the cutter head and the frictional resistance between the pipe sections and formation at the same time. In particular, the pipe-soil frictional resistance increases with the increases of jacking distance, buried depth, pipe diameter and the complexity of jacking trajectory. Therefore, it is very important to correctly estimate jacking force in trenchless jacking engineering practice for the smooth implementation of pipe jacking, operation risk and comprehensive cost control. Firstly, the stress states of jacking circular and rectangular pipe sections in the soil are analyzed, and the key influencing factors of their pipe-soil frictional resistance are obtained respectively. Then, the pipe-soil frictional resistance of jacking the circular and rectangular pipe sections with the same external surface area in the dry sandy soil and coal granular layer are tested separately by using the self-developed multifunctional experimental apparatus during trenchless pipe jacking. The results show that the pipe-soil frictional resistances of jacking circular and rectangular pipe sections in the coal granular layer are always smaller than that in the sandy soil under the same experimental conditions, and the corresponding fitting calculation equation of pipe-soil frictional resistances are obtained respectively. Meanwhile, the modified calculation methods of the above pipe-soil frictional resistances are proposed respectively based on the relationship between the lateral pressure coefficient K and the buried depth of pipe section H. Moreover, the disturbed area of soil in the upper part of jacking circular pipe section presents an arc distribution, while the disturbed area of soil in the upper part of jacking rectangular pipe section presents a slightly concave distribution. Due to the different disturbance conditions of soil around the pipe section, the lateral pressure coefficient K should be corrected in the calculation equations of pipe-soil frictional resistance of jacking circular and rectangular pipe sections based on the discrete element numerical simulation analysis by EDEM software. Finally, the pipe-soil frictional resistances obtained by different methods in the sandy soil are compared and analyzed. The calculated values of the modified theoretical calculation method are very close to the experimental test values, while the other methods are smaller than the experimental test values, which makes the rationality of the modified theoretical calculation method of pipe-soil frictional resistance is verified, and some suggestions are also put forward for the value of some coefficients in the relevant empirical estimation equations. The above research achievements systematically compared the states of pipe-soil frictional resistances of jacking circular and rectangular pipe sections based on different research methods, especially for the correct evaluation of jacking force during trenchless pipe jacking, they could provide some valuable references and effective guidance for the subsequent research, engineering practice and further development of trenchless pipe jacking technology. [ABSTRACT FROM AUTHOR]

Rock bolts are extensively utilized in underground engineering as a means of offering support and stability to rock masses in tunnels, mines, and other underground structures. In environments of high ground stress, faults or weak zones can frequently arise in rock formations, presenting a significant challenge for engineering and potentially leading to underground engineering collapse. Rock bolts serve as a crucial structural element for the transmission of tensile stress and are capable of withstanding shear loads to prevent sliding of weak zones within rock mass. Therefore, a complete understanding of the behavior of rock bolts subjected to shear loads is essential. This paper presents a state-of-the-art review of the research progress of rock bolts subjected to shear load in three categories: experiment, numerical simulation, and analytical model. The review focuses on the research studies and developments in this area since the 1970s, providing a comprehensive overview of numerous factors that influence the anchorage performance of rock bolts. These factors include the diameter and angle of the rock bolt installation, rock strength, grouting material, bolt material, borehole diameter, rock bolt preload, normal stress, joint surface roughness and joint expansion angle. The paper reviews the improvement of mechanical parameter setting in numerical simulation of rock bolt shear. Furthermore, it delves into the optimization of the analytical model concerning rock bolt shear theory, approached from the perspectives of both Elastic foundation beam theory coupled with Elastoplasticity theory and Structural mechanic methods. The significance of this review lies in its ability to provide insights into the mechanical behavior of rock bolts. The paper also highlights the limitations of current research and guidelines for further research of rock bolts. [ABSTRACT FROM AUTHOR]

The two-dimensional (2D) cross-hole seismic computed tomography (CT) imaging acquisition method has the potential to characterize the target zone optimally compared to surface seismic surveys. It has wide applications in oil and gas exploration, engineering geology, etc. Limited to 2D hole velocity profiling, this method cannot acquire three-dimensional (3D) information on lateral geological structures outside the profile. Additionally, the sensor data received by cross-hole seismic exploration constitute responses from geological bodies in 3D space and are potentially affected by objects outside the well profiles, distorting the imaging results and geological interpretation. This paper proposes a 3D cross-hole acoustic wave reverse-time migration imaging method to capture 3D cross-hole geological structures using sensor settings in multi-cross-hole seismic research. Based on the analysis of resulting 3D cross-hole images under varying sensor settings, optimizing the observation system can aid in the cost-efficient obtainment of the 3D underground structure distribution. To verify this method's effectiveness on 3D cross-hole structure imaging, numerical simulations were conducted on four typical geological models regarding layers, local high-velocity zones, large dip angles, and faults. The results verify the model's superiority in providing more reliable and accurate 3D geological information for cross-hole seismic exploration, presenting a theoretical basis for processing and interpreting cross-hole data. [ABSTRACT FROM AUTHOR]

Legal boundaries are used for delineating the spatial extent of ownership property's spaces. In underground environments, these boundaries are defined by referencing physical objects, surveying measurements, or projections. However, there is a gap in connecting and managing these boundaries and underground legal spaces, due to a lack of data model. A 3D data model supporting underground land administration (ULA) should define and model these boundaries and the relationships between them and underground ownership spaces. Prominent 3D data models can be enriched to model underground legal boundaries. This research aims to propose a new taxonomy of underground legal boundaries and model them by extending CityGML, which is a widely used 3D data model in the geospatial science domain. We developed, implemented, and tested the model for different types of underground legal boundaries. The implemented prototype showcased the potential benefits of CityGML for managing underground legal boundaries in 3D. The proposed 3D underground model can be used to address current challenges associated with communicating and managing legal boundaries in underground environments. While this data model was specifically developed for Victoria, Australia, the proposed model and approach can be used and replicated in other jurisdictions by adjusting the data requirements for underground legal boundaries. [ABSTRACT FROM AUTHOR]

With the rise of low-cost and high-density observation system Distributed Acoustic Sensing (DAS), the effective utilization of high-mode surface wave becomes extremely important due to unique measuring method of DAS. To solve the interference of mode identification of dispersion curve and model dimension division on inversion results, we introduced the fitting degree of the dispersion curve, the model dimension, and the uncertainty estimation of the picked dispersion curve to construct a new objective function, and developed a strategy of adaptive trans-dimensional inversion of multimode dispersion curve based on slime mold algorithm (SMA). The research results show that our objective function can not only satisfy the fitting degree of dispersion curve, but also adaptively select the best model dimension, and does not depend on the mode identification of dispersion curve. Inversion strategy based on SMA algorithm has high flexibility, accuracy, stability, and practicality. Our method develops a new technology for dispersion curve inversion and provides a new idea for DAS system to realize low-cost and high-resolution city underground structure detection. [ABSTRACT FROM AUTHOR]

Face passive failure can severely damage existing structures and underground utilities during shallow shield tunneling, especially in coastal backfill sand. In this work, a series of laboratory model tests were developed and conducted to investigate such failure, for tunnels located at burial depth ratios for which C/D = 0.5, 0.8, 1, and 1.3. Support pressures, the evolution of failure processes, the failure modes, and the distribution of velocity fields were examined through model tests and numerical analyses. The support pressure in the tests first rose rapidly to the elastic limit and then gradually increased to the maximum value in all cases. The maximum support pressure decreased slightly in cases where C/D = 0.8, 1, and 1.3, but the rebound was insignificant where C/D = 0.5. In addition, the configuration of the failure mode with C/D = 0.5 showed a wedge-shaped arch, which was determined by the outcropping shear failure. The configuration of failure modes was composed of an arch and the inverted trapezoid when C/D = 0.8, 1, and 1.3, in which the mode was divided into lower and upper failure zones. [ABSTRACT FROM AUTHOR]

The drill and blast (D&B) method is widely used to excavate underground spaces, but explosions generally cause damage to the rock. Still, no blast simulation method can provide computational accuracy and efficiency. In this paper, a blast equivalent simulation method called the blast damage zone strength reduction (BDZSR) method is proposed. This method first calculates the range of the blast-induced damage zone (BDZ) by formulae, then reduces the strength and deformation parameters of the rock within the BDZ ahead of excavation, and finally calculates the excavation damage zone (EDZ) for the D&B method by numerical simulation. This method combines stress wave attenuation, rock damage criteria and stress path variation to derive the BDZ depth calculation formulae. The formulae consider the initial geo-stress, and the reliability is verified by numerical simulations. The calculation of BDZ depth with these formulae allows the corresponding numerical simulation to avoid the time-consuming dynamic calculation process, thus greatly enhancing the calculation efficiency. The method was applied to the excavation in Jinping Class II hydropower station to verify its feasibility. The results show that the BDZSR method can be applied to blast simulation of underground caverns and provide a new way to study blast-induced damage. [ABSTRACT FROM AUTHOR]

The construction of pipe jacking has little impact on the environment and is usually used to build underground passages with shallow buried depths and short lengths. Compared with circular pipe jacking, rectangular pipe jacking has the advantages of shallow buried depth and high space utilization. Therefore, research on the excavation of rectangular pipe jacking is necessary. This paper establishes a cross-section model of shallow buried rectangular pipe jacking excavation. Taking advantage of complex functions for solving problems involving non-circular tunnels, an analytical solution is obtained using an approximate mapping function and potential functions in series forms for the stress and displacement of the stratum with a displacement condition at the excavation boundary and a stress condition at the ground surface boundary. The finite element simulation results and the engineering-measured data are used for comparisons and verifications. With the analytical solution of the complex function, the influence of selecting control points for the mapping function on the accuracy is calculated and analyzed, as well as the influence of the stratum loss rate, span, buried depth, and stratum unit weight on surface subsidence and major principal stress of the excavation boundary. The proposed analytical solution can be applied to the construction of rectangular pipe jacking tunnels. [ABSTRACT FROM AUTHOR]

Rockburst is a common ground pressure disaster in underground geotechnical engineering. The frequent occurrence of rockburst hazards severely threatens the security of construction workers and facilities on site. Considering the shortcomings of the existing research methods, such as low prediction accuracy, poor interpretability and ignoring the weights of input parameters, this study proposes a new method for predicting short-term rockburst using RF–CRITIC and an improved cloud model (RCICM). Of these, random forest (RF) and CRITIC algorithms were used for optimizing the weights of the prediction indicators, and the cloud model was improved in three aspects: numerical characteristics correction, membership calculation optimization and validity inspection under membership boosting. Six microseismic (MS) parameters were used as inputs to the model, including the accumulative quantity of MS events, accumulative MS energy, accumulative MS apparent volume, event rate, energy rate and apparent volume rate. A random sampling method was used to divide the 105 MS rockburst samples into a training set and a test set, and the model was trained and evaluated separately. The model achieved prediction accuracy of 85.7% on the independent test set, an improvement of 14.3% over the original cloud model. The model was then validated on five rockburst cases at the Asher Copper Mine, the New Jersey Hydroelectric Project tunnels and the Qinling Water Conveyance Tunnel, and correct predictions were obtained. The model has optimal predictive capability compared to existing machine learning models. The sensitivity analysis results revealed the input parameters' influence on the rockburst level and the applicability of the RCICM model with different input parameters. The proposed model has excellent accuracy and applicability and can offer valuable guidance for the safe construction of underground geotechnical engineering. [ABSTRACT FROM AUTHOR]

Equity, Diversity, and Inclusion (EDI) are important to drive innovation in many different fields, including particle physics. Underground labs are working on many different fronts to improve EDI in their host countries and within particle physics collaborations. Laboratories can institute policies to protect their staff and make improvements to their facilities to increase accessibility. Laboratories can encourage the scientific collaborations they host to have policies and plans for increasing EDI. SNOLAB and the Sanford Underground Research Facility (SURF) are each supporting their employees and user-bases in different ways. Some examples are targeted outreach, consultation with experimental collaborations on their own policies, EDI training, and Indigenous cultural recognition. These efforts are intended to enhance the equity and inclusion of their communities. [ABSTRACT FROM AUTHOR]

Low-temperature cryogenics open the door for a range of interesting technologies based on features like superconductivity and superfluidity, low-temperature phase transitions or the low heat capacity of non-metals in the milli- Kelvin range. Devices based on these technologies are often sensitive to small energy depositions as can be caused by environmental radiation. The Cryogenic Underground TEst facility (CUTE) at SNOLAB is a platform for testing and operating cryogenic devices in an environment with low levels of background. The large experimental chamber (0(10) L) reaches a base temperature of ~ 12 mK; it can hold a payload of up to ~ 20 kg and provides a radiogenic background event rate as low as a few events/kg/keV/day in the energy range below about 100 keV, as well as a negligible muon rate (01)/month). CUTE was designed and built in the context of the Super Cryogenic Dark Matter Search experiment (SuperCDMS) that uses cryogenic detectors to search for interactions of dark matter particles with ordinary matter. The facility has been used to test SuperCDMS detectors since its commissioning in 2019. In 2021, it was handed over to SNOLAB to become a SNOLAB user facility after the completion of the testing of detectors for SuperCDMS. The facility will be available for projects that benefit from these special conditions, based on proposals assessed for their scientific and technological merits. This article describes the main design features and operating parameters of CUTE. [ABSTRACT FROM AUTHOR]

This study presents a systematic workflow for estimating hydrogen storage capacity for a smooth energy transition from natural gas market to hydrogen market to achieve net-zero emissions. The workflow establishes maximum and minimum thresholds for hydrogen storage and considers appropriate storage techniques, including underground or surface facilities. The technique assesses environmental footprint of each storage technique and evaluates associated emission reductions. We apply this workflow to energy market in Alberta and project minimum and maximum storage thresholds of 0.28 and 5 megatonne/year (Mt/year) by 2050. Under three distinct storage scenarios, the storage capacity necessitates 128 salt caverns, 10 million compressed gas tanks, or 78,150 cryogenic liquefied tanks. Salt cavern storage emerges as a promising choice owing to its relatively lower emissions of 0.16 MtCO 2 e/year and a land footprint of 2.56 km2. The net emission reduction achieved is 1.47 MtCO 2 e/year, equivalent to 0.8% of Canada's target emission reduction of 190 MtCO 2 e/year by 2050. • A workflow is developed to forecast required hydrogen storage capacity in Alberta. • Salt caverns emerge as a reliable and practical technique for large-scale hydrogen storage. • The workflow projects the required number of salt caverns for hydrogen storage. • Supplying stored hydrogen to market reduces 1.5 megatonne/year of GHG emissions. [ABSTRACT FROM AUTHOR]

Rockburst is a serious disaster caused by the sudden release of rock energy during underground construction in high-stress environments, resulting in severe damage to underground structures. Accurately predicting rockburst intensity is challenging, and establishing a reliable and precise prediction model is of great importance. In this study, we proposed a novel hybrid model for predicting rockburst intensity by integrating rough set theory and multidimensional cloud model uncertainty reasoning. The key steps of the proposed method are as follows: (1) Rockburst cases are collected, and the maximum shear stress σ θ , uniaxial compressive strength σ c , uniaxial tensile strength σ t , and elastic energy index W et are used as predictors for rockburst strength. (2) The Shannon entropy method is used to determine the weights of the four indicators, and a rockburst potential expression is constructed. (3) Rough set theory is used to reduce the number of indicators to construct a rockburst strength prediction rule library. (4) Qualitative data are transformed into quantitative data using the rules library and multidimensional cloud model to establish an uncertainty inference framework for predicting rockburst strength. Finally, we compared the performance of the hybrid model with existing models, and the results demonstrate that the proposed approach achieves similar or even higher prediction accuracy. The use of cloud droplets in the model offers a significant advantage in the prediction of mixed rockburst intensities, enabling intuitive, rapid, and effective determination of the occurrence intensity of rockburst. [ABSTRACT FROM AUTHOR]

Underground engineering construction will inevitably change the stress state of surrounding strata, which will force a negative impact on the surrounding environment, even leading to the large deformation and damage of some adjacent structures. With a focus on the deformation of a typical soil–rock composite stratum site in the construction of Changchun Metro, relying on the shield construction of a parallel twin tunnel project between Northeast Normal University Station and Gong-Nong Square Station, which belongs to the Changchun Metro Line 1, the site deformation characteristics during the shield driving process of parallel twin tunnels were studied. Based on the data obtained from field monitoring and numerical simulation, ground settlement in shield driving was analyzed, the settlement trough was studied with the Peck formula, and the action of shield driving on the adjacent tunnel was discussed. Moreover, the influence range of shield driving was suggested, and the interaction between the twin tunnels with different axis spacings in shield driving was discussed. Some regular results obtained can provide support through data for similar projects in Changchun, China. [ABSTRACT FROM AUTHOR]

In this paper, a resilience assessment framework for microencapsulated self-healing cementitious composites is proposed based on a micromechanical damage-healing model. A 3D micromechanical analytical model is constructed to analyze the performance evolution during the damage-healing process of self-healing concrete. The resilience assessment of microencapsulated self-healing concrete is defined by virtue of the residual stiffness, self-healing effect on stiffness and damage cumulative on stiffness, which corresponds to three main features of resilience; namely, the robustness, recoverability and adaptability. The assessment results indicate that the release of healing agents within microcapsules and healing process of extended microcracks allows the microencapsulated self-healing concrete to have higher resilience than conventional concrete. Moreover, a parameter sensitivity analysis is conducted to investigate the influence of the healing efficiency, the applied initial damage and the fracture toughness of the repaired microcrack on resilience of microencapsulated self-healing concrete. The results indicate that higher healing efficiency and applied initial damage leads to high resilience, and fracture toughness of the repaired microcrack makes less difference to the results. The findings of this paper lay a theoretical foundation for the resilience design of self-healing material layer of underground structures. [ABSTRACT FROM AUTHOR]