Search Results (998)

The intensification of ground pressure and instability of surrounding rock in deep mining are the core safety challenges of metal mines. This article takes the first mining area of the Sishanling Iron Mine from 960 m to 1020 m as the object, and based on the data obtained from the multi-channel microseismic monitoring system for the whole year of 2025, combined with monthly mining and filling parameters, conducts a rock mass risk assessment that couples microseismic activity with the mining and filling process. The results show that microseismic activity and blasting operations exhibit a significant “resonance of the same frequency” response. The event-intensive areas are distributed along the fault zone and the edge of the goaf, and migrate in a directional manner from shallow to deep with the advancement of mining. By comparing the photos of the tunnel damage on site on a monthly basis, it was found that the incident gathering area was highly consistent with the locations of roof collapse and debris support, which verified the accuracy of microseismic positioning. Based on this, a risk discrimination index based on event frequency, energy release rate, and spatial concentration was established to dynamically evaluate the −960 m and −1020 m sections on a monthly basis. The local risk intensity in the −1020 m section was higher, and the risk increased compensatorily when the filling was delayed 2–4 weeks after mining, revealing the key control role of the mining filling coordination rhythm on the stability of the surrounding rock. The coupled evaluation system of mining filling microseismic risk constructed in this study can provide technical reference for active early warning and differentiated prevention and control of ground pressure in deep mines. Full article

Foliated metamorphic rock exists widely in the surrounding rock of tunnel structures, underground utility caverns and mountain civil structures, and its laminated foliation structure induces obvious anisotropic time-dependent creep deformation, which seriously threatens the long-term service safety of underground building support systems. The strength and time-dependent deformation of foliated phyllite vary sharply with bedding dip angles, and long-term creep easily triggers large convergence, secondary-lining cracking and structural intrusion failure of tunnel structures. In this work, multi-stage uniaxial compression creep tests were carried out on sericite phyllite specimens with foliation dip angles of 0°, 30°, 45° and 90° using a programmable rock creep testing apparatus, aiming to investigate the anisotropic creep behaviors of phyllite surrounding rock for tunnel engineering. The anisotropic P-wave velocity characteristics of phyllite under different bedding angles were first analyzed to quantify the directional structural difference in the rock matrix. Based on the creep test curves, the full-stage deformation laws including instantaneous strain, decelerating creep, steady-state creep and accelerating creep were systematically summarized for specimens with different bedding orientations. Combined with macroscopic creep failure modes, phenomenological analysis was performed on the anisotropic creep damage behavior controlled by foliation weak planes. The results demonstrate that inclined bedding phyllite presents the most severe creep deformation and steady-state creep rate, and three typical creep failure modes (cross-bedding shear failure, tensile splitting failure, bedding slip shear failure) correspond to horizontal, vertical and inclined foliation specimens respectively. This study quantitatively reveals the time-dependent anisotropic mechanical properties of foliated soft rock, establishes a systematic experimental database and provides experimental basis for long-term stability prediction, and enriches the rheological research system for the durability evaluation of underground civil structures. Full article

In greenhouses with evaporative cooling systems, the amount of water used for cooling can exceed plant water consumption, so caution is advised in water-scarce regions. Since the semi-arid region where the study was conducted receives low rainfall (an average of 380.4 mm per year), the amount of water used for plant and evaporative cooling makes water use management a critical issue. For this purpose, a study was conducted between May and July 2023 in Kırşehir, Türkiye, using two physically identical, side-by-side, polyethylene-covered high tunnels (5 m × 3 m × 2 m) with external shading nets; one operating with natural ventilation (NV) and the other with direct evaporative cooling (DEC). The study determined the effects of these applications on the indoor climate, the morphological and quality characteristics of tomatoes, plant water consumption, and water-use efficiency. During the study period, the highest cooling effect measured in the DEC application was 9.6 °C, the relative humidity effect was 29.3%, and the cooling efficiency was 67.6%. In the NV application, the highest cooling effect was 5.0 °C, and the relative humidity effect was 13.2%. As a result of the findings, the DEC application made a positive contribution to the morphological (stem diameter, plant height, and number of leaves) and quality parameters (width, length, weight, pH, titratable acidity, and total soluble solids) of tomatoes compared to the NV application. Daily plant water consumption per unit area was 114.7 L m⁻² in the NV application, 88.1 L m⁻² in the DEC application, and 117.5 L m⁻² for cooling. The amount of water used for irrigation in the NV application was approximately 23.2% higher than in the DEC application. In the study, total yield (TY) was 2355.5 g m⁻², and marketable yield (MY) was 2240.8 g m⁻² under NV application. In the DEC application, TY was 5721.5 g m⁻² and MY was 5529.8 g m⁻². Accordingly, TY decreased by 58.8% and MY decreased by 59.5% in the NV application compared to the DEC application. Total water-use efficiency (TWUE) was 20.5 g L⁻¹ in the NV application, while marketable yield water-use efficiency (MWUE) was 19.5 g L⁻¹. In the DEC application, TWUE was 42.2 g L⁻¹ while MWUE was 39.6 g L⁻¹. Accordingly, compared to the DEC application, TWUE decreased by 51.4%, and MWUE decreased by 50.8% in the NV application. Furthermore, considering the water used for cooling in the DEC application (irrigation + cooling), CTWUE was 27.8 g L⁻¹, and CMWUE was 26.9 g L⁻¹. Therefore, the water used for DEC reduced CTWUE by 34.1% and CMWUE by 32%. The results indicate that while evaporative application has positive contributions to cultivation, it also reduces water-use efficiency; therefore, its use should be considered in regions with limited water availability. Collecting rainwater and using it in irrigation and as cooling water after filtration will be important for sustainable greenhouse farming in these regions. Full article

Tunnel blasting adjacent to existing transmission towers may induce foundation vibration and transient deformation, affecting the response evaluation of transmission tower foundations. This study investigates the blast-induced response characteristics of three in-service high-voltage transmission towers adjacent to the Langjiafan Railway Tunnel. Field monitoring was conducted at different longitudinal distances to obtain three-component peak particle velocities (PPVs) and dominant frequencies. Site-specific vibration attenuation relationships were established using the Sadovsky empirical model, and a three-dimensional tunnel–rock mass–transmission tower numerical model was developed and validated against field measurements. The results show that the PPVs generally increased as the tunnel face approached the towers, and the vertical component exhibited relatively larger responses under the investigated blasting conditions. The maximum vertical PPVs of Towers No. 1–3 were 0.9563, 1.1253, and 1.5198 cm/s, respectively, corresponding to 38.3%, 45.0%, and 60.8% of the adopted control value of 2.5 cm/s. The dominant frequencies mainly ranged from 20 to 65 Hz in the horizontal directions, while the vertical components exhibited higher-frequency characteristics under certain blasting conditions. The Sadovsky models achieved coefficients of determination of 0.927, 0.923, and 0.903, and the numerical model reproduced the measured vibration attenuation trends with mean relative errors of 12.48–13.22%. The maximum transient differential foundation displacements of Towers No. 1–3 were 0.1064, 0.1947, and 0.1433 mm, respectively. The results indicate that both foundation vibration velocity and transient deformation should be considered when evaluating the response of transmission tower foundations subjected to adjacent tunnel blasting. The findings provide site-specific references for vibration monitoring and blast-induced response control of existing transmission tower foundations under similar underground blasting conditions. Full article

The spectral line density of an optical frequency comb (OFC) generated in a microring resonator is fixed by the free spectral range (FSR), and hence by the resonator size: the dense combs required for spectroscopy, optical clocks, and high-capacity communications conventionally demand centimeter-scale cavities, in direct conflict with photonic integration. Here, we propose a route around this FSR–footprint trade-off using topological ring resonators (TRRs) built on a silicon valley photonic crystal (VPC) platform. Evanescently coupling two identical TRRs, an optical analog of quantum tunneling in a double-well potential, deterministically splits each resonance into a doublet of supermodes (Rabi splitting), doubling the spectral line density within a fixed bandwidth while the parallel two-ring layout occupies orders of magnitude less chip area than a single conventional ring of equivalent effective FSR. A coupled-mode-theory model quantitatively captures the splitting observed in full-wave 3D finite-difference time-domain (FDTD) simulations, and the topological protection of the valley edge states preserves the doublet against lattice disorder; a fabrication-tolerance analysis shows the splitting varies by only a few percent for nanometer-scale gap errors. Nonlinear simulations based on the coupled nonlinear Schrödinger equation indicate that the doubled supermode grid translates directly into a denser comb, increasing the generated line count from 48 to 122 under identical Kerr-only pumping conditions. An explicit nonlinear-loss budget, including two-photon and free-carrier absorption, bounds these results for silicon at 1550 nm and identifies mid-infrared silicon and TPA-free platforms such as silicon nitride as physically realistic implementations. This design study establishes coupled topological resonators as a compact, disorder-tolerant architecture for high-density comb generation, which can potentially be experimentally demonstrated. Full article

The deep-sea tunnels at the Sanshan Island Gold Mine are subjected to extreme conditions characterized by high stress and complex erosion resulting from high mineralization. Under these conditions, conventional shotcrete is prone to performance degradation and insufficient durability, posing a threat to the long-term safety of the tunnels. At the same time, mine water is difficult to recycle on-site. To address these engineering challenges, this study utilized fly ash (FA), S105-grade ground granulated blast furnace slag (GGBS), polypropylene coarse fiber (PPCF), and hydroxypropyl methylcellulose (HPMC) as modifying components and employed the response surface method (RSM) to optimize the mix design of mine water-blended shotcrete. The study selected compressive strength, direct shear strength, and chloride ion electrical flux at 6 h as response indicators and constructed a quadratic polynomial regression model. Analysis of variance and goodness-of-fit tests indicated that the model possessed good significance and reliability of fit. Based on this model, the optimal mix design was determined: an FA/GGBS blend ratio of 3:7, a cement replacement rate of 20%, a PPCF content of 3.3%, and an HPMC content of 0.18%. Performance testing showed that the optimal mixture achieved a compressive strength of 25.24 MPa, a direct shear strength of 8.08 MPa, and a chloride ion electrical flux of 778 C after 6 h. Compared to the control group, its peak compressive strength decreased by only 9.98%, while its residual strength increased significantly; direct shear strength increased by 18.1%, and electrical flux decreased by 33.8%. This indicates that the material’s mechanical load-bearing capacity, deformation coordination, and corrosion resistance have been enhanced in a synergistic manner. Field industrial trials have verified that this modified concrete possesses excellent ductile yield characteristics, can effectively suppress water seepage in mine tunnels, is capable of withstanding extreme underground operating conditions, and enables the efficient reuse of mine water resources. Full article

As a transition zone between open road environments and enclosed tunnel spaces, urban tunnel entrances undergo rapid variations in spatial structure, lighting conditions, and traffic-related semantic information over short distances. These abrupt environmental changes impose considerable visual demands on drivers and may adversely affect the reliability of autonomous driving perception systems. However, existing studies have primarily investigated individual environmental factors, while lacking a systematic parameterized framework capable of characterizing multi-source environmental features and their coupled effects on visual perception. To address this limitation, this study proposes a multidimensional and multilevel environmental parameter system for urban tunnel entrances based on a Structure–Lighting–Traffic (SLT) coupling framework. First, considering the formation mechanism of visual information, environmental factors influencing perception performance in tunnel entrance zones are categorized into three dimensions: spatial structure, lighting environment, and traffic semantics, thereby establishing a unified representation framework. Subsequently, an SLT coupling model is developed, incorporating parameter gradient intensity, coupling strength, and dispersion characteristics to quantitatively characterize the spatial variation and interaction patterns of environmental parameters. Furthermore, by integrating autonomous driving perception tasks, the relationships between environmental parameter variations, image quality degradation, and perception performance are investigated. The proposed framework is validated using field measurements collected from the entrance zones of 20 urban tunnels in Chongqing, China. The results reveal pronounced spatial heterogeneity and directional asymmetry in tunnel entrance environments. The entrance transition sections exhibit the characteristics of “high variation, strong coupling, and low stability,” whereas exit transition sections demonstrate more complex multi-factor interactions due to the combined effects of structural variations, intense light intrusion, and overlapping traffic information. Compared with structural and traffic-related factors, lighting variations play a dominant role in the degradation of overall visual perception performance. The proposed SLT-based environmental parameter system establishes a unified representation framework linking human visual perception mechanisms with machine vision perception modeling, providing theoretical support for autonomous driving perception optimization, complex scene understanding, and safety risk assessment in urban tunnel environments. Full article

Ultrasonic pulse-echo imaging is one of the most widely used non-destructive evaluation (NDE) modalities for monitoring the structural integrity of reinforced-concrete civil infrastructure such as bridge decks, tunnel linings, and dam walls. In this acquisition geometry, a single low-frequency transducer is mechanically raster-scanned over the accessible top surface of the specimen and records one A-scan per scan position, simultaneously serving as transmitter and receiver. However, commonly used reconstruction algorithms such as the Synthetic Aperture Focusing Technique (SAFT) and Reverse Time Migration (RTM) tend to produce reconstructions of limited quality on this class of data because they do not adequately model the round-trip propagation kernel that is specific to the monostatic geometry, they do not separate the strong near-surface direct-arrival reflection from the bulk image, and they do not account for the persistent aggregate-induced clutter that contaminates every A-scan in concrete media. In this paper, we propose a clutter-aware reconstruction method for monostatic ultrasound acquisition (CARMA), whose main innovation is the joint integration of a monostatic-specific round-trip propagation model, a dedicated near-surface direct-arrival subspace, and a data-adaptive low-rank clutter subspace within a unified model-based reconstruction framework. Unlike existing reconstruction approaches, CARMA explicitly accounts for the co-located transmit–receive geometry through a squared-cosine round-trip directivity model while simultaneously separating scan-dependent direct-arrival contributions and aggregate-induced clutter from the desired reflectivity image. To verify the method under fully controlled and repeatable conditions, we generate intensive, physically realistic full-wave simulations with the k-Wave pseudo-spectral acoustic solver that reproduce a representative civil-infrastructure inspection scenario: three reinforced-concrete specimens with a stepped back wall of varying thickness, ten embedded ground-truth defects spanning steel tendon ducts and low-impedance polystyrene inclusions, a monostatic raster-scanned pulse-echo acquisition, and randomly distributed aggregate scatterers that reproduce the clutter of real concrete. Results on these intensive k-Wave simulations indicate that CARMA reconstruction yields approximately $2\times$ lower localization error than RTM and approximately $4\times$ lower localization error than SAFT, while recovering the deepest embedded defect with substantially better localization and contrast than the comparison methods. Full article

Small gases pose an unusual problem for studies of molecular transport in proteins. O₂, CO, H₂, and NO can cross short-lived internal spaces opened by protein fluctuations, often faster than experiments can follow continuous migration. Time-resolved crystallography can localize sufficiently populated intermediates, whereas spectroscopy, isotope exchange, and kinetic measurements report molecular exchange over their respective timescales without resolving the complete route. Pressurized noble-gas structures expose internal accommodation sites but rely on surrogate molecules whose size and interactions differ from those of physiological gases. Geometry-based tunnel searches identify available space, while molecular dynamics follows explicit movement through a fluctuating protein. Free-energy and enhanced-sampling approaches can access states or transitions that remain undersampled in direct trajectories. These techniques resolve different quantities rather than progressively more accurate estimates of gas transport. In this Perspective, we argue that gas-migration pathways should be evaluated by the physical consistency of independent observables, with each method interpreted according to the quantity it resolves. This distinction explains why a cavity visible crystallographically may not carry substantial flux, why a rapidly crossed route can remain structurally inconspicuous, and why static narrowing can alter diffusion without predicting its magnitude. Agreement among methods can support a transport assignment when the quantities they resolve are physically consistent with the same mechanism; apparent disagreement may instead reflect differences among occupancy, accessibility, residence, energetic preference, and molecular traffic. Full article

Large deformation is one of the most critical hazards in tunnels excavated under complex geological conditions. It often causes significant economic losses and threatens construction safety. For layered soft rock tunnels subjected to high in situ stress, the deformation and failure mechanisms are largely governed by the bedding dip angle. To clarify these mechanisms and optimize the corresponding construction control measures, this study investigates a carbonaceous slate section of a railway tunnel in the Western Sichuan Plateau. Field monitoring and FLAC3D numerical modelling are coupled. The influence of the bedding dip angle on the plastic-zone evolution and the failure modes of the surrounding rock is analysed. The micro-bench, three-bench, and reserved core soil methods, together with the rock bolt length, are comparatively evaluated. On this basis, a differentiated reinforcement strategy is proposed for bedding-induced asymmetric loading. The results indicate that: (1) The bedding dip angle governs the failure mode of the surrounding rock. Under the micro-bench method, the plastic zone in subvertically bedded rock masses exhibits a quasi-symmetrical distribution along the normal direction of the bedding planes. The sidewalls predominantly undergo flexural failure. In contrast, under bedding-induced asymmetric loading, the plastic zone concentrates at the left springline and right shoulder. An asymmetric composite failure mode is formed, characterized by shallow flexural–tensile cracking and deep-seated interlayer shear. (2) Under the subvertical bedding condition (89°), the reserved core soil method mitigates the excavation-induced unloading disturbance most effectively. It achieves the lowest peak stress and the smallest tunnel convergence, which is 15.7% and 33.0% lower than those of the micro-bench and three-bench methods, respectively. Its plastic zone reaches full numerical convergence. The reserved core soil method is therefore identified as the optimal excavation Scenario under this condition. (3) The rock bolt length exhibits a threshold effect on deformation control. The most substantial improvement occurs when the bolt length is increased from 4 m to 6 m, beyond which the benefit tends to plateau. A bolt length of 6 m is therefore recommended as the best-performing Scenario among the tested values (4, 6, 8, and 10 m) for the investigated geological and support conditions. For surrounding rock subjected to bedding-induced asymmetric loading, a differentiated reinforcement strategy targeting the vulnerable zones reduces the maximum deformation by 18.8% and 28.3% compared with the uniform reinforcement Scenario and the baseline Scenario, respectively. These findings provide practical insights into excavation-method selection and support optimization for layered soft rock tunnels under similar conditions. Full article

LiDAR–inertial odometry (LIO) is accurate in structurally rich environments but can become weakly observable in tunnels, stairways, and open terrain. This study introduces a degeneracy-aware, intensity-assisted LIO method that uses LiDAR reflectivity as an internal sensing modality without requiring a camera. Raw returns are projected onto a normalized panoramic intensity image, and image patches are selected according to their ability to complement the uninformative directions identified from the geometric information matrix. Point-to-plane, photometric, and inertial residuals are then fused in an iterated extended Kalman filter. Unlike fixed-scale intensity fusion, the proposed strategy adjusts the photometric residual scale according to the number of weak geometric directions and smooths this scale temporally. Experiments on the Newer College, ENWIDE, and GEODE datasets show that adaptive scaling reduces translational ATE RMSE, defined as the sequence-level root-mean-square of pose-wise translational absolute pose errors, by 11–40% on four ablation sequences. On GEODE-Stairs, the method obtains an ATE RMSE of 0.26 m, which is 46.9% lower than that of COIN-LIO. It also achieves the lowest ATE RMSE on each of the four tunnel sequences, with values ranging from 0.30 to 0.33 m. Mean processing times range from 15 to 25 ms per scan, corresponding to an average throughput of 40.0–66.7 scans/s on the evaluated platform. These results indicate that degeneracy-conditioned intensity fusion improves LIO robustness while maintaining average throughput compatible with real-time operation. Full article

This paper presents a method for monitoring damage evolution at sandstone-binding material interfaces by combining a Vision Transformer (ViT) deep learning model with piezoelectric ultrasonic monitoring. Direct shear tests were conducted on bonded weak sandstone specimens. The results indicate that the damage evolution process can be divided into four stages: initial elastic, compaction and stabilization, crack propagation and coalescence, and frictional sliding and interlocking. Ultrasonic signals acquired during loading reveal that interface damage evolution is in good agreement with the time-domain waveforms, Continuous Wavelet Transform (CWT) time–frequency spectra, and wavelet packet energy. Based on the ViT-Small/16 backbone, a ViT model with adaptive frequency-feature extraction was developed for small-sample and cross-specimen interfacial damage-stage identification, using the Stage I health observations of each specimen prior to loading as the reference. Results from five repeated runs with different random seeds show that the method achieved an accuracy of 93.23% ± 0.72% and an F1-score of 92.32% ± 0.90%, demonstrating favorable recognition performance and stability under the current condition. This study offers insights into the damage monitoring and subsequent warning of similar binary interfaces in tunnel engineering, geotechnical engineering, and stone cultural heritage conservation. Full article

A laboratory Hertz-like gravitational wave communication system (“gravity radio”) is proposed using coherent optical-stress sources in high-Q optical fiber ring-resonator arrays. Hyperentangled photon pairs and coincident tunneling events provide timing, phase, and correlations, while the gravitational source is the local, conserved field-plus-medium stress-energy tensor generated by phase-locked coherent optical fields. Because the electromagnetic stress tensor is quadratic in the fields, the source can contain both sum-frequency and difference-frequency components. The latter is emphasized because it relaxes the localization, phase-stability, and receiver-transduction requirements. The directed coherent transverse-traceless stress amplitude and receiver equivalent strain noise are derived for a meter-scale transfer test. Full article

Abrupt changes in the lighting environment at highway tunnel entrances, transition zones, and exits can impose substantial visual adaptation demands on drivers. This real-vehicle study evaluated a modified LED tunnel lighting environment designed to enlarge the effective luminous area, improve road surface lighting uniformity, and reduce direct glare, compared with the original lighting system. The field experiment was conducted using 24 licensed drivers in a 610 m highway tunnel. Pupil area, mean fixation duration, and heart rate growth rate (HRG) were recorded in six longitudinal zones under the original and modified lighting conditions. The measured interior zone illuminance uniformity increased from 0.71 to 0.87 after modification. Repeated-measures ANOVA showed significant lighting-by-zone interactions for all three outcomes (p ≤ 0.001). Bonferroni-adjusted comparisons localized significant reductions in pupil area and HRG in the threshold, transition, and interior zones, while fixation duration increased significantly in those zones and in the exit zone. Across the averages for the six zones, pupil area decreased by 8.39%, HRG decreased by 13.78%, and mean fixation duration increased by 6.63%. The findings suggest that the modified lighting environment reduced visual adaptation demand and physiological arousal, especially in the threshold and transition zones. Fixation duration changes are interpreted as altered visual information processing rather than direct evidence of improved safety, and no inference about crash reduction can be made without direct driving performance or safety outcome data. Full article

Rock slope landslide potential, tunnel design, and the engineering of underground spaces critically require an analysis of rock joint orientation and spacing. Joint set measurements are typically determined by hand in the field using a compass–clinometer to measure the orientation of the geologic planes with respect to north and the dip of the plane with respect to the horizontal. Unmanned aerial vehicles (UAVs) can be utilized to capture hundreds of photos to create high-resolution 3D models of a rock outcrop, capturing visible joint set discontinuities on a faceted surface of a triangular irregular network (TIN). Computing methods of facets and facet normals from a point cloud allow for the characterization of discontinuity orientations without the need for manual measurements in the field. However, these methods used to calculate facets and facet normals result in the addition of noise in the dataset, which increases the difficulty of analysis. A two-stage filtering process employing density-based spatial clustering of applications with noise (DBSCAN), and the second derivative of the remaining clusters, removes data that are not representative of a discontinuity within the intact rock mass. Finally, an unsupervised clustering algorithm, K-Means Clustering, is applied to the dataset to extract the dip and dip direction of discontinuities. The methodology used to identify the orthogonal joint sets on a dam spillway demonstrated good performance across all identified joint sets, with the estimated variability in dip and dip direction broadly comparable to that observed in the manual field dataset. This indicates that this newly developed proof-of-concept approach can reliably capture the orientation and variability of orthogonal joint sets from large datasets. Full article