网络首发
Engineering properties of cement-based grout toughened with modified rice husk fiber
Zhang Jianjun;Han Jian;Sun Chuang;Sun Yuanjun;Zhao Taofeng;Wang Baoqiang;Grouting is a vital technique for controlling the stability of fractured surrounding rock. To address the limitations of traditional cement-based grouting materials—such as high brittleness， poor deformation adaptability， and susceptibility to cracking and failure—a novel toughened cement-based grouting material has been developed by incorporating modified Rice Husk Fiber (RHF)， which underwent treatment through crushing， acid boiling， alkali soaking， and surface coating. We conducted slurry fluidity tests and experiments on the unconfined compressive strength， flexural strength， and static elastic modulus of the hardened specimens to determine the slurry’s setting time， flowability， and bleeding rate. By analyzing the stress-strain curves and failure modes of the samples， we investigated the influence and toughening effect of RHF incorporation on the engineering properties of cement-based grouting materials to identify the optimal fiber content. Furthermore， microstructural characterization techniques such as Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) were employed to elucidate the toughening mechanism of RHF within the cement matrix. The results indicate that: (1) As RHF content increases， the slurry's flowability， bleeding rate， and compressive strength gradually decrease， while the initial and final setting times are prolonged. The flexural strength initially increases before decreasing. Notably， the axial strain of the specimens rises， post-peak residual strength improves， the compressive failure mode transitions from columnar brittle splitting to ductile shear failure， and flexural cracks evolve from brittle bending cracks to ductile bending–shear cracks， demonstrating enhanced deformation compatibility of the material. The optimum toughness is achieved at an RHF content of 3‰. (2) RHF forms an effective bond with the cement matrix through interfacial friction， adhesion， and interlocking effects， providing bridging， pull-out， and fracture resistance. This inhibits crack development， enhances the deformation capacity and energy absorption characteristics of the material， and leads to improved toughness in cement-based grouting materials. These research findings provide a scientific basis for optimizing grouting reinforcement materials for fractured surrounding rock and ensuring engineering safety.
Analysis of coal mine accident characteristics under the transformation of production factors in China(2010-2024)
WANG Qifei;LIU Shuai;YAO Jinbo;HAO Chengliang;LI Bei;WANG Junlong;SUN Yingfeng;To identify the evolution of coal mine accidents and the effects of production-factor changes on safety performance in China during 2010–2024， this paper combines macro statistical data with panel data from 23 major coal-producing provinces and examines the coordinated changes in labor， capital， and technology. First， descriptive statistical analysis is used to examine accident numbers， fatalities， fatality rate per million tons， spatial distribution， and accident-type structure， so as to reveal the overall trend， regional shift， and type evolution of coal mine accidents. Then， a two-way fixed effects model is employed to estimate the net effects of output from large-scale enterprises， employment， labor productivity， male-to-female employment ratio， total wages， average wages， and fixed-asset investment on the number of fatalities. The results show that the total number of accidents， fatalities， and fatality rate per million tons all declined markedly over the study period， although low-level fluctuations reappeared after the trough in 2021. High-risk areas shifted from eastern and southern regions toward the main coal-producing regions in western and northern China， and the dominant accident pattern changed from traditional hazards such as gas and blasting accidents to roof， transport， and electromechanical accidents characterized by stronger human-machine coupling. The regression results indicate that employment (t = 5.436， P< 0.01) and output from large-scale enterprises (t = 3.520， P< 0.01) significantly increase fatality risk. In contrast， labor productivity (t = -2.172， P< 0.05)， fixed-asset investment (t = -1.971， P= 0.05)， male-to-female employment ratio (t = -2.799， P< 0.01)， and total wages (t = -3.334， P< 0.01) significantly reduce the number of fatalities， whereas the effect of average wages is not statistically significant. These results indicate that coal mine safety risk is increasingly manifested as a coupled human-machine-environment-management risk under high-intensity production. Future governance should therefore focus on the main production regions， old mining areas， and the rising shares of roof， transport， and electromechanical accidents， while promoting coordinated optimization of labor， capital， and technology.
Multimodal Sensing-Based Control of Unsafe Behaviors for Urban Rail Transit Construction Workers
Xie Weicheng;Zhao Honggang;Zhang Yi;Xie Pinhan;Huang Xiao;To address the issues of fragmented multi-source information， subjective and static evaluation， and lack of closed-loop control in the supervision of unsafe behaviors of construction workers in urban rail transit projects， this study proposes an intelligent control method integrating multimodal perception and dynamic quantitative assessment. A collaborative data collection architecture covering visual， physiological， and environmental elements was constructed to capture multi-source heterogeneous data. Dynamic time warping and Daubechies wavelet threshold denoising were applied to achieve spatiotemporal alignment and noise suppression of the collected data. A CNN-LSTM hybrid recognition model integrating channel and temporal attention mechanisms was designed with a dual-stream parallel encoding and fusion decoding architecture. Specifically， an improved ResNet-50 with Squeeze-and-Excitation modules was utilized to extract visual spatial features， while a three-layer 1D-CNN was employed to encode sensor sequences. Dual-branch LSTM networks were then constructed to model the temporal dependencies of both visual and sensor streams. A gating fusion strategy was introduced to dynamically adjust the fusion weights of multimodal features via a Sigmoid function. Furthermore， a weighted cross-entropy loss function with a high-risk penalty coefficient of 3.0 was adopted to effectively handle the severe class imbalance problem. A dynamic quantitative evaluation model based on risk accumulation theory was proposed， incorporating a time decay factor (λ=0.95) for safety behavior scoring and a sensitivity coefficient (0.05) for physiological safety scoring. This evaluation model maps unsafe behaviors and physiological abnormalities into continuous and traceable safety scores divided into three risk levels. Finally， a closed-loop control platform was developed and empirically validated in a real-world urban rail transit project. Results show that the proposed model achieved an accuracy of 94.6%， precision of 93.8%， recall of 92.5%， and F1 score of 93.1% for typical unsafe behaviors. The system cumulatively identified 93 unsafe behaviors and successfully handled 7 high-level warning events. The monthly safety violation rate of the project decreased from 4.39% in the baseline period to 3.79% in the pilot period， representing a significant reduction of 13.7%. The proposed method effectively overcomes the recognition bottleneck of single modality in complex working conditions， realizing dynamic perception and proactive intervention of construction workers' safety risks. It provides a reusable technical paradigm for the digital and refined transformation of construction safety management.
Study on multi-objective optimisation in the construction phase of building projects under carbon emission constraints
Wu Mingliang;Yuan Chunyan;Wang Wen;Yao Hongli;This study develops a five-objective optimization framework for the construction phase of building projects under carbon emission constraints. The framework integrates project duration， cost， quality， safety， and carbon emissions into a unified multi-objective model， treating construction activities and their alternative execution modes as decision units. The model quantifies the attributes of each candidate mode and transforms the actual construction organization problem into a computable combinatorial optimization problem by incorporating precedence relationships， exclusive mode-selection constraints， schedule limits， cost bounds， and quality and safety thresholds. In the model structure， quality and safety are treated as constraint-type objectives to ensure minimum engineering and risk-control requirements， while duration， cost， and carbon emissions are regarded as core optimization objectives for trade-off analysis. To solve the proposed problem， an Non-dominated Sorting Genetic Algorithm II based optimization procedure is employed to generate Pareto non-dominated solutions. An empirical analysis is conducted using a public building project in Xi’an， China. The project is decomposed into 17 key construction activities， each associated with two or three feasible execution modes， resulting in 17 006 112 candidate construction schemes. The parameters for duration， cost， quality， carbon emissions， and safety for each activity are determined through schedule analysis， quantity takeoff， pricing software， carbon emission factor calculation， and safety-cost-based risk evaluation. The proposed solution method is further compared with the Genetic Algorithm (GA) algorithm under identical parameter settings using Hypervolume (HV)， Inverted Generational Distance (IGD)， and spacing indicators. The results demonstrate that the proposed NSGA–Ⅱ–based approach achieves superior convergence， distribution uniformity， and solution stability compared to the GA in solving the five-objective problem. The obtained Pareto front effectively illustrates the nonlinear trade-offs among duration， cost， quality， safety， and carbon emissions， providing differentiated decision support for scenarios prioritizing time， cost， low carbon emissions， or balanced solutions. This study shows that the proposed model and solution framework can facilitate the scientific selection of construction schemes in complex multi-constraint environments.
Leakage-induced fracture failure mode and risk assessment in high-pressure carbon dioxide pipelines
Shi Lei;Zhou Liguo;Wang Xiaolin;Liu Zhenxi;Yan Xingqing;Yu Jianliang;A review of the Pipeline and Hazardous Materials Safety Administration database and existing literature reveals that leakage is the most common failure type in carbon dioxide pipelines. Factors such as material failure， corrosion， and external mechanical damage can create through-wall defects that lead to leakage. This study analyzes crack tip field parameters—including the stress intensity factor (K)， J-integral， crack tip opening displacement (δ)， and crack tip opening angle (CTOA)—along with the critical fracture toughness of materials， discussing their definitions and failure criteria. The significant adverse effects of low-temperature environments on the critical fracture toughness of pipeline materials are explained， particularly noting that critical fracture toughness declines sharply in the ductile-to-brittle transition zone， exhibiting pronounced size effects and statistical scatter. Based on the master curve model， which predicts the quantitative relationship between critical fracture toughness and temperature， a failure mode is developed wherein carbon dioxide leakage causes a local temperature drop in the pipe material， triggering crack initiation at defect sites. The evolution path includes several stages: the formation of local defects leading to leakage; the initial crack tip field parameter being lower than the material's critical fracture toughness; carbon dioxide expansion causing cooling; significant temperature drops in the pipe material near the defect; a marked reduction in the steel’s critical fracture toughness; the critical fracture toughness decreasing to match the value of the defect’s crack tip field parameter; and finally， the initiation and propagation of the defect. Using defects located in the girth welds of X65 pipeline steel as an example， a risk assessment was conducted. The calculations show that when the reference temperature is -50 ℃ and the pipe material temperature drops below -39 ℃， the defect’s stress intensity factor exceeds the critical value， resulting in crack propagation. When the reference temperature is -100 ℃crack propagation is triggered if the pipe material temperature falls below -69 ℃ under the same criterion. It is recommended that both the crack tip field parameter model and the material critical fracture toughness model be incorporated into safety assessments and monitoring strategies for carbon dioxide pipelines， with particular attention paid to the effects of low temperatures on materials in leakage-prone regions.
Study on the preparation of magnesium-based composite inhibitor and its characteristics of inhibiting coal spontaneous combustion
Bai Gang;Wang Shuoshuo;Li Xueming;Zhang Xiaowen;Huang Ge;Lu Bing;In response to prevalent issues such as low inhibition efficiency， short duration of effectiveness， susceptibility to failure at high temperatures， and potential toxicity of by-products associated with current coal spontaneous combustion inhibitors， this study leverages the environmentally friendly， low-cost， and high-temperature stability of magnesium-based materials to develop a composite inhibitor. This inhibitor combines magnesium chloride (MgCl?) and magnesium hydroxide [Mg(OH)?]. A series of experiments—including synchronous thermal analysis， gas measurement， scanning electron microscopy， and in-situ Fourier transform infrared spectroscopy—were conducted to investigate the thermal behavior of coal samples， determine the optimal parameter combination for the inhibitor， and elucidate the underlying microscopic mechanisms. The results indicate that both the mass fraction of the inhibitor and the mass ratio of MgCl? exert a nonlinear influence on inhibition performance， initially enhancing it before leading to a decline. In contrast， the mass fraction of the silane coupling agent has a relatively minor effect. The optimal parameters for the composite inhibitor were identified as: an inhibitor mass fraction of 30%， an Mg(OH)?/MgCl? mass ratio of 1:2， and a silane coupling agent mass fraction of 1.5%. Under these conditions， the net heat release of the inhibited coal sample below 300 °C was reduced by 130 J/g compared to raw coal. The activation energy during the oxygen-absorption weight-gain stage and the pyrolysis stage increased by 41.3 kJ/mol and 66.9 kJ/mol， respectively. Moreover， the maximum inhibition rate reached 80%， with an inhibition lifetime extending to 210 minutes. SEM observations revealed significantly improved dispersion and a more uniform， dense distribution of elements on the surface of the inhibited coal sample. Mechanistically， during the low-temperature stage， MgCl? forms a liquid water film due to its strong hygroscopicity， which not only isolates oxygen from the coal surface but also acts as a uniform dispersion medium for Mg(OH)?. As the temperature rises， the dehydration of MgCl? produces gaseous water， thereby dissipating some oxidation heat. Concurrently， the thermal decomposition of Mg(OH)? yields high-melting-point MgO， forming a continuous， dense coating over the coal surface that provides sustained barrier protection at elevated temperatures.
Study on cross-sectional width parameters of underground interchange ramps based on driving safety reliability
Zhang Chi;Gao Yanyang;Tang Xie;Song Jinming;Lin Guojin;This study aimed to clarify the relationship between cross-sectional width parameters and driving safety performance on underground interchange ramps of mountainous expressways. A driving simulation experiment was conducted based on nine scenarios formed by different combinations of lane width， lateral width， and alignment type. Thirty licensed drivers were recruited to complete heavy-truck driving tasks in the simulated underground ramp environment. Vehicle operation data and eye-movement data were collected synchronously during the experiment. The test section was divided into 10 m spatial windows to maintain spatial consistency in the analysis. Lateral offset， minimum lateral margin， and normalized gaze entropy were extracted for each window. Lateral offset and minimum lateral margin were used to describe vehicle lateral control and boundary proximity. Normalized gaze entropy was used to quantify the dispersion of drivers’ visual attention among different areas of interest. Based on these indicators， the effects of cross-sectional width parameters on vehicle lateral operation and visual attention allocation were analyzed. A response surface model was then developed to predict the minimum lateral margin and normalized gaze entropy under different combinations of lane width， lateral width， operating speed， and alignment type. Driver differences， spatial-window fluctuations， and the correlation between the two safety performance indicators were further incorporated into Monte Carlo simulation. A system driving safety reliability model was established by considering insufficient lateral margin and excessive visual-attention dispersion as two failure modes. The results show that the lateral adjustment amplitude and trajectory fluctuation on curved sections are greater than those on straight sections. Normalized gaze entropy is higher on the right-turn curve than on the straight section and the left-turn curve， indicating a more dispersed visual search pattern. Lateral width has a significant effect on both minimum lateral margin and normalized gaze entropy. Increasing lateral width improves the lateral safety margin and reduces the dispersion of visual attention. System driving safety reliability increases with lateral width and decreases with operating speed. Taking the target reliability of 0.95 as the control level， when the lane width is 3.50 m， the lateral width values for straight， left-turn， and right-turn sections can be taken as 0.75， 0.75， and 1.00 m， respectively.
Impact of digital transformation in coal enterprises on work safety
Wang Xiangqian;Li Ruiying;Guo Puhao;Jin Huayi;This study aims to explore the non-linear impact of digital transformation in coal enterprises on safety production while elucidating the underlying mechanisms and boundary conditions. Addressing the limitations of existing research that primarily focus on linear relationships， we adopt the theoretical perspective that "too much is as harmful as too little" to investigate whether an optimal "critical point" for digital transformation exists. Utilizing unbalanced panel data from Chinese A-share coal-listed companies spanning 2009 to 2023， we employ a bidirectional fixed-effects regression model for empirical testing. We use "annual increase in special reserves" as a proxy variable for safety production and introduce "internal control" and "innovation capability" as dual mediating variables to examine their transmission paths. Additionally， we consider "corporate Environmental， Social， and Governance (ESG) performance" as a moderating variable to assess its influence on the primary effect. To ensure the robustness of our conclusions， we conducted a series of tests， including U-shaped relationship analysis， instrumental variable methods， lagged model analysis， and variable substitution. The research reveals a significant inverted U-shaped relationship between digital transformation and safety production in coal enterprises， with an inflection point at approximately 10.50. Mechanism analysis indicates that digital transformation similarly affects internal control (inflection point at 8.70) and corporate innovation (inflection point at 9.98) through an inverted U-shaped path， which subsequently influences safety production. Furthermore， strong ESG performance positively moderates this inverted U relationship， shifting the curve upward and to the right， thereby optimizing the safety benefits of digital transformation. Heterogeneity analysis further reveals that this nonlinear relationship is more pronounced in central and eastern regions， larger enterprises， and central state-owned enterprises. This study transcends linear thinking by demonstrating that "digitalization does not inevitably enhance safety，" highlighting the critical effects of potential harm and the intrinsic dual mediating transmission mechanisms involved. This contributes to interdisciplinary research on the economic consequences of digital transformation and safety management while providing important theoretical support and practical insights for coal enterprises on how to scientifically assess their investments， manage the pace of transformation， and achieve a dynamic balance between safety and development in the advancement of intelligent processes.
Effects and mechanisms of mineral silicon materials on cadmium-lead contaminated paddy soil
Huang Zulü;Liu Jingyi;Xiao Hao;Zhang Junhao;Huang Yi;Fu Hui;Jiang Shaojun;This study evaluated two silicon-based materials derived from solid wastes—stone powder-based silicon material (SSM) and lead-zinc tailing-based silicon material (TSM)—for immobilizing cadmium (Cd) and lead (Pb) in contaminated paddy soils. A pot experiment was conducted using two typical mining-affected soils (DBS and FKM). For each soil type， five treatments were established: control， 0.5% TSM， 1% TSM， 0.5% SSM， and 1% SSM. The two materials were compared based on their effects on soil properties， Cd/Pb bioavailability， rice growth and grain safety， and soil microbial communities. TSM consistently outperformed SSM， reducing available Pb by 66%–81% and available Cd by 35%–62%. The superior performance of TSM was attributed to its multi-mineral composition， which raised soil pH， enhanced iron plaque formation on rice roots (reflected by higher Fe and Mn levels in DCB extracts)， and released silicate and alkaline earth ions that promoted competitive adsorption and co-precipitation of Cd and Pb. SSM exhibited moderate effects only at 0.5%， while 1% SSM elevated soil pH above 8.0， leading to complete rice mortality. TSM treatments increased tiller numbers (by 22%–33% in DBS soil) and grain yield. In DBS soil， 1% TSM reduced brown rice Cd levels to 0.15–0.19 mg/kg and Pb levels to 0.12–0.18 mg/kg， both below national food safety limits. In contrast， SSM reduced grain Cd and Pb only at the 0.5% concentration， indicating a narrow safe dose window. TSM also preserved bacterial alpha diversity (Chao1 index) and maintained stable community structure， enriching functional phyla such as Proteobacteria and Bacteroidetes. Several genera (Lacibacter， Flavisolibacter) showed positive correlations with available Cd and Pb， suggesting their potential as bioindicators of metal immobilization. Conversely， 1% SSM sharply reduced alpha diversity and caused a distinct community shift， coinciding with phytotoxicity. In conclusion， TSM derived from lead-zinc tailings can effectively immobilize Cd and Pb， preserve soil ecological functions， and ensure rice grain safety， providing a practical option for tailing utilization and remediation. In contrast， SSM should be used cautiously due to its narrow safe dose window.
Ecological compensation zoning of the Huaihe River Basin based on ecosystem service value
He Gang;Fu Yiwen;Zhang Shiyu;Scientifically quantifying ecosystem service value and establishing appropriate ecological compensation zoning are crucial measures to alleviate the spatial imbalance between ecology and economy， thereby enhancing coordinated and sustainable development in the Huaihe River Basin. This study employs the equivalent factor method to calculate the ecosystem service value (ESV) of 30 prefecture-level cities in the Huaihe River Basin from 2010 to 2024. We construct a three-dimensional indicator system comprising “ecological supply–ecological pressure–economic support” by coupling ecological carrying capacity (EC)， ecological footprint (EF)， and economic development levels. The EM-K-means++ clustering algorithm is utilized to conduct ecological compensation zoning and analyze the spatial patterns in the upstream， midstream， and downstream regions. The XGBoost-SHAP model is employed to explore the significance and directionality of multidimensional driving factors impacting ecological compensation zoning， with multi-scale analyses performed at both the basin and sub-basin levels. The results indicate that: (1) From 2010 to 2024， ESV， EC， and EF in the Huaihe River Basin exhibit a temporal characteristic of “unimodal aggregation and synergistic evolution，” with water area identified as the dominant contributor to ESV. (2) The ecological compensation zones can be categorized into five types: high compensation zone， low compensation zone， balanced zone， high payment zone， and low payment zone， revealing a pattern of “supply agglomeration in the upper and middle reaches and consumption differentiation in the lower reaches.” This zoning pattern has gradually evolved from fluctuation and differentiation to stability. (3) The driving mechanisms behind ecological compensation zoning in the Huaihe River Basin demonstrate a significant feature of “global commonality and local heterogeneity.” These findings promote a scientific matching between ecological contributions and compensation rights and responsibilities， providing a solid basis and spatial support for implementing the horizontal ecological compensation mechanism in the Huaihe River Basin.