Search Results (286)

Distributed acoustic sensing (DAS) is a highly effective method of monitoring all kinds of intrusions on railway tracks. These intrusions represent a real problem in the railway sector, as they can lead to human deaths or damage to railway tracks, and these intrusions may be human or animal. A fiber was deployed along 12 km of track in a railway test center, enabling us to acquire data day and night. A data acquisition campaign was carried out in April 2023 to capture the signatures of several scenarios (walking, digging, falling rocks, etc.) in order to train machine learning models and prevent any intrusion by detecting and classify these intrusion. The study shows the diversity of signals that fiber can acquire in the rail sector and the machine learning model performance. Signals associated with the presence of animals are also presented. Full article

In order to examine the fracture development law of overlying strata in goafs and to reasonably lay out a high gas-drainage roadway under gob-side entry retaining with roadside filling, the 91–105 working face of the Wangzhuang Coal Mine was selected as the engineering case study. The failure laws and fracture development characteristics of the overlying strata in both the strike and dip directions using gob-side entry retaining and roadside filling were studied through rock mechanic tests and PFC numerical simulations. The optimal layout of the high gas-drainage roadway was determined through theoretical analysis and coupled Fluent–PFC numerical simulations, and on-site monitoring was conducted to evaluate the extraction effects. The results indicate that the first weighting interval of the 91–105 working face was 40 m, while the periodic weighting interval was approximately 14 m. The height of the falling zone was 14.4 m, and the height of the gas-conducting fracture zone was 40.7 m. In the dip direction, compared with coal pillar retaining, gob-side entry retaining with roadside filling formed an inverted trapezoid secondary breaking zone above the retaining roadway. Using this method, the span of the separation zone increased to 30 m, and the collapse angle decreased to 52°, resulting in a shift in the separation zone—the primary space for gas migration—toward the goaf. It was determined that the optimal location of the high gas-drainage roadway was 28 m above the coal roof and 30 m horizontally from the return air roadway. Compared with the 8105 working face, this position was 10 m closer toward the goaf. On-site gas extraction monitoring data indicate that, at this optimized position, the gas concentration in the high gas-drainage roadway increased by 22%, and the net gas flow increased by 18%. Full article

This study aims to mitigate slope-collapse hazards that threaten life and property at the Lujiawan resettlement site in Wanbi Town, Dayao County, Yunnan Province, within the Guanyinyan hydropower reservoir. It integrates centimeter-level point-cloud data collected by a DJI Matrice 350 RTK equipped with a Zenmuse L2 airborne LiDAR (Light Detection And Ranging) sensor with detailed structural-joint survey data. First, qualitative structural interpretation is conducted with stereographic projection. Next, safety factors are quantified using the limit-equilibrium method, establishing a dual qualitative–quantitative diagnostic framework. This framework delineates six hazardous rock zones (WY1–WY6), dominated by toppling and free-fall failure modes, and evaluates their stability under combined rainfall infiltration, seismic loading, and ambient conditions. Subsequently, six-degree-of-freedom Monte Carlo simulations incorporating realistic three-dimensional terrain and block geometry are performed in RAMMS::ROCKFALL (Rapid Mass Movements Simulation—Rockfall). The resulting spatial patterns of rockfall velocity, kinetic energy, and rebound height elucidate their evolution coupled with slope height, surface morphology, and block shape. Results show peak velocities ranging from 20 to 42 m s⁻¹ and maximum kinetic energies between 0.16 and 1.4 MJ. Most rockfall trajectories terminate within 0–80 m of the cliff base. All six identified hazardous rock masses pose varying levels of threat to residential structures at the slope foot, highlighting substantial spatial variability in hazard distribution. Drawing on the preceding diagnostic results and dynamic simulations, we recommend a three-tier “zonal defense with in situ energy dissipation” scheme: (i) install 500–2000 kJ flexible barriers along the crest and upper slope to rapidly attenuate rockfall energy; (ii) place guiding or deflection structures at mid-slope to steer blocks and dissipate momentum; and (iii) deploy high-capacity flexible nets combined with a catchment basin at the slope foot to intercept residual blocks. This staged arrangement maximizes energy attenuation and overall risk reduction. This study shows that integrating high-resolution 3D point clouds with rigid-body contact dynamics overcomes the spatial discontinuities of conventional surveys. The approach substantially improves the accuracy and efficiency of hazardous rock stability assessments and rockfall trajectory predictions, offering a quantifiable, reproducible mitigation framework for long slopes, large rock volumes, and densely fractured cliff faces. Full article

Vertical PGA is frequently included in civil engineering regulations simply by multiplying the horizontal PGA by a constant. Moreover, most design codes, including Eurocode 8, do not consider the impact of the local soil on vertical ground motion at all. In this study, we demonstrate that such practices increase earthquake risks. The article examines vertical PGA strong-motion estimations for the city of Banja Luka. Banja Luka serves as a case study for areas with records of moderate to strong earthquakes and diverse deep geological conditions. Regional equations for scaling vertical PGA are presented. The vertical PGA values and vertical to horizontal PGA ratios are calculated and analyzed. The findings indicate that the vertical to horizontal PGA ratios for the rock sites depend on the source-to-site distance and deep geology and fall between 0.30 and 0.66. Hence, these ratios cannot be approximated by a single value of 0.90 and 0.45, as specified by Eurocode 8 for Type 1 and Type 2 spectra, respectively. Moreover, the results show that the deep geology effects on vertical ground motion can exceed the local soil effects. When the amount of recorded data from comparable areas increases, we will be able to properly calibrate the existing scaling equations and obtain more reliable estimates of vertical PGA. Full article

This study was conducted to characterize and classify soils and rocks and to produce an engineering geological map that is beneficial for overall urban planning. The soils’ moisture content and specific gravity values range from 23.47% to 44.21% and 2.68 to 2.81, respectively. The activity of soils varies from 0.34 to 0.78 (inactive to normal). The shrinkage limit and shrinkage index values of soils range from 5% to 11.43% and 14.29% to 26.9%, respectively. Free swell value varies from 5 to 23% (low expansive). The unconfined compressive strength of soils ranges from 215.8 to 333.5 kPa (very stiff). According to USCS (Unified Soil Classification System), soils are classified into lean clay, lean clay with sand, fat clay with sand, and clayey silt with slight plasticity. According to BSCS (British Soil Classification SystemS), soils are classified into clay of intermediate plasticity, clay of high plasticity, and silt of intermediate plasticity. Rocks were classified into four categories based on their mass strength: very low mass strength, low mass strength, medium mass strength, and high mass strength. The RQD Rock Quality Designatione) value ranges from 47.48% to 98.25%, indicating a quality range from poor to excellent. The RMR Rock Mass Ratinge) values range from 44 to 90%, indicating that the rocks of the study area fall into three major classes: Class I (very good), Class II (good), and Class III (fair). Full article

The Shionomisaki Igneous Complex is part of the Mid Miocene igneous province developed within the Shimanto Accretionary Complex in front of the volcanic front in SW Japan. The igneous rocks in this province mostly have silicic compositions. New U-Pb ages obtained for two samples from the Shionomisaki Complex at the southern tip of the Kii Peninsula (14.6 ± 0.4 Ma and 14.9 ± 0.4 Ma) fall into the range of previous age determinations (14.6 ± 0.2 to 15.4 ± 0.3 Ma). Hf isotopic compositions obtained for co-magmatic zircon (εHf(t) = −0.7 to +4.8) lie between typical values obtained for mantle-derived magmas and values obtained for old crustal rocks. They are thus consistent with previous interpretations that the magmas are mixtures of mantle and crustally derived magmas. In the modelling of the isotopic characteristics of the magmas, the sediments of the Shimanto belt are taken as the protolith of the silicic magmas. Xenocrystal zircon (i.e., zircon picked up during ascent and emplacement of the magma) found in the silicic igneous rocks exhibits a similar age pattern as detrital zircon of the Shimanto sediments. However, the age pattern obtained in this study for zircon cores, which are considered to be restitic zircon (i.e., zircon derived from the source of the anatectic melt), shows little semblance with the age pattern of Shimanto sediments. It is, therefore, tentatively suggested that the source area of the silicic magmas may not be identical with the sediments of the Shimanto Accretionary Complex. Full article

Fresh groundwater is essential for sustaining life and socio-economic development, particularly in regions with limited safe drinking water alternatives. However, contamination from natural and anthropogenic sources poses severe health and environmental risks. This research examines the health risks linked to groundwater quality in the agroeconomic region of Boudh district, Odisha, India, where residents depend on untreated groundwater due to limited access to alternative sources. A total of 82 groundwater samples were analyzed during pre- and post-monsoon of the year 2023 using multivariate statistical methods (PCA, correlation analysis) to determine pollutant sources and regulatory factors, while XRD was employed to characterize fluoride-bearing minerals in associated rock samples. Fluoride concentrations range from 0.14 to 4.6 mg/L, with 49% of samples exceeding the WHO limit of 1.5 mg/L, which raises significant health concerns. Nitrate levels fluctuate between 1.57 and 203.51 mg/L, primarily due to agricultural fertilizers. A health risk assessment (hazard quotient and hazard index) indicates that 63% of samples fall into the low-risk category, 21% into moderate-risk, and 16% into high-risk. Children (HI = 29.23) and infants (HI = 19.51) are at the greatest health risk, surpassing that of adult males (HI = 12.2) and females (HI = 11.2). Findings provide scientific evidence for policymakers to implement groundwater protection and remediation strategies. Immediate interventions, including water quality monitoring, defluoridation measures, and community awareness programs, are essential for ensuring long-term water security and public health. Full article

The Pliensbachian–Toarcian boundary and early Toarcian events indicate significant environmental and oceanographic instabilities attributed to the emplacement of the Karoo–Ferrar large igneous province and subsequent greenhouse gas emissions. These geologic processes influenced carbon cycle perturbations and global warming, consistent with phases of a sea level rise. This study presents a high-resolution dataset of total organic carbon (TOC) and bulk rock geochemistry and mineralogy from a complete upper Pliensbachian–Toarcian interval of the Quse Formation at the Qixiangcuo section in the Southern Qiangtang Basin. The Qixiangcuo section consists of carbonate and siliciclastic organic carbon-poor sediments deposited in a shallow-shelf setting in the eastern Tethys Ocean. Chemostratigraphic data, including Ti, Zr, U, Ca, Mn, and Sr and their ratios normalized to Al, record characteristic changes linked to sea level evolution and resulting depositional sequences. Trends in these geochemical data allow for the subdivision of the Quse Formation into nine complete third-order transgressive–regressive sequences, referred to as Pliensbachian sequences PSQ1 and PSQ2, Toarcian sequences TSQ1 to TSQ7, and one incomplete sequence. Elemental proxies indicative of terrigenous detrital input and sediment grain size along with a mineralogical composition of quartz, plagioclase, and clay minerals exhibit similar trends. Increased values of these proxies suggest a sea level fall and the deposition of regressive systems tract (RST) sediments, with peak values indicating a maximum regressive surface (MRS), and vice versa for transgressive systems tract (TST) sediments and the maximum flooding surface (MFS). On the contrary, rising trends in calcite content and carbonate-bound elements indicate phases of a relative sea level transgression, reaching maximum values at the MFS, while declining trends mark a sea level regression. The Sr/Ca ratio exhibited inverse patterns to the carbonate proxies, in part, with rising values indicating a sea level fall and vice versa. Full article

The fall pipe rock dumping technique is extensively employed to create protection embankments around submarine cables, mitigating distortion and breakage resulting from bottom scouring. During the rock dumping operation, intricate interactions among the pipeline, rocks, and water currents can affect the stability and efficiency of the fall pipe system. This research proposed a method employing the fluid–structure interaction to analyze the interactions between the pipeline, rocks, and water currents. The paper begins with the design of an innovative fall pipe rock dumping system and presents a theoretical analysis of the applied model testing approach. The simulation parameters were determined according to the geometric, Froude, and Strouhal similarity criteria. A thorough numerical analysis was performed to investigate the hydrodynamic properties of the rockfall pipeline under fluid–structure interaction. The research examined the settling of rocks during rockfall, along with the forces and movements associated with the deposition process. The results show that the rockfall pipeline experienced vortex-induced vibrations (VIVs) caused by ocean currents during operation. The maximum settling velocity of the rocks throughout the rockfall process reached 2.2 m/s, with a final stable velocity of 1.5 m/s. These simulation results offer critical insights for improving the design and functionality of the rockfall pipeline, thereby enhancing the protection of underwater infrastructure. Full article

During coal resource mining, hard roof mining is prone to causing rock-burst disasters because traditional blasting–cutting roof technology has the disadvantages of low efficiency and high cost. This article studies the theoretical basis and engineering application of fracturing technology with a static expansion agent (SCA). The influences of borehole diameter and spacing on the fracturing effect of a rock mass are studied through theoretical analysis and simulation. Rock mass models of a cantilever beam for a single rock layer and multiple layers were established, and the mechanical properties of the roof strata under three working conditions were analyzed. The research results show that the maximum annular stress value occurs along the drill hole wall between the adjacent drill holes, and the annular stress at the center line between two drill holes is the smallest. As the spacing between the holes increases, the annular stress at the center line decreases; however, the annular stress at the center of the drill line becomes larger with the increase in hole diameter. The degree of stress concentration increases sharply with the decrease in distance f from the borehole center to the free surface. Relative to the cantilever beam model of a single rock layer, the combined rock layers can effectively control the displacement and deformation of the cantilever roof. Based on the above research results, a drilling method with a 75 mm diameter and a 10° inclination angle is used, demonstrating that the suspended roof area can be reduced to below 20 m² using the fracturing technology with a static expansion agent, allowing the roof strata to fall simultaneously during mining. Full article

Discontinuity damage and shear strength weakening under dynamic loading are important causes of engineering rock instability. To study the damage mechanism of rock discontinuities under dynamic loading and the law of shear strength weakening after disturbance, the dominant controlling factors of dynamic loading-induced discontinuity damage were analyzed using the discrete element method. The evolution characteristics and formation mechanism of discontinuity damage were revealed, and the shear strength weakening law of discontinuities under dynamic loading was quantitatively characterized and verified by laboratory tests. The results are as follows: (1) Due to the symmetry of the structural distribution and material properties, a 2D UDEC-Tri model containing a discontinuity specimen was established. The number of failure blocks and the crack development length were calculated using Fish scripting in UDEC. Based on the orthogonal design method, it was found that the dominant controlling factors of dynamic load-induced discontinuity damage are the dynamic load frequency, peak dynamic load, and cycle number. (2) In the rising stress stage, the discontinuity mainly accumulates energy, causing minor damage with slight shear crack development. In the falling stress stage, energy release increases the damage, leading to significant shear and tensile crack growth with a hysteresis effect. The cracks are symmetrically distributed on both sides of the discontinuity. (3) The greater the damage to the discontinuity caused by the dynamic load disturbance, the more obvious the shear strength weakening after the disturbance. By comprehensively considering the symmetry characteristics of the damage distribution and strength weakening law of the discontinuity, and based on mathematical analysis, the model of discontinuity shear strength weakening after dynamic load disturbance was established. The model considers three dominant controlling factors: the dynamic loading frequency, peak dynamic load, and cycle number. The research results reveal the damage mechanism of discontinuities under dynamic loading and obtain the shear strength weakening law, which provides a reference for the stability evaluation of engineering rock masses under dynamic loading. Full article

The water contents and geochemical evidence of nominally anhydrous minerals in peridotite xenoliths provide critical insights into lithospheric mantle features, offering a deep understanding of cratonic destruction and mantle evolution processes. Damaping, located in the central part of the intra-North China Craton, hosts abundant mantle peridotite xenoliths’ samples, providing new constraints on lithospheric mantle evolution. In this study, spinel lherzolite samples from Damaping Cenozoic basalts were analyzed for major and trace elements, water content, and oxygen isotope to investigate the factors controlling mantle water distribution and lithospheric mantle modification. The olivines of Damaping spinel lherzolite have a range of Mg# values from 89.73 to 91.01, indicating moderately refractory mantle characteristics. Clinopyroxenes display an LREE-depleted pattern, suggesting a consistency with 1–6% of batch partial melting and 1–5% fractional partial melting. The high (La/Yb)_N (0.20–0.73) and low Ti/Eu (3546.98–5919.48) ratios of Damaping clinopyroxenes reveal that the lithosphere mantle beneath the Damaping has undergone silicate metasomatism. The water contents of Damaping clinopyroxenes and orthopyroxenes range from 13.39 to 19.46 ppm and 4.60 to 7.82 ppm, respectively. The water contents of the olivines are below the detection limit (<2 ppm). The whole-rock water contents can be estimated based on the mineral modes and partition coefficients, with values ranging from 3.21 to 5.44 ppm. Partial melting indicators (Mg# in Ol and Yb_n in Cpx) correlate with the water content in clinopyroxenes and orthopyroxenes but show no correlation with the redox state (Fe³⁺/∑Fe ratios in spinel) or metasomatism ((La/Yb)_N in clinopyroxene). These results suggest that the degree of partial melting primarily controls the heterogeneous water distribution in Damaping spinel lherzolite, rather than the redox state or metasomatism. The δ¹⁸O values of clinopyroxenes from Damaping spinel lherzolites (5.27–5.59‰) fall within the range of mid-ocean ridge basalts (MORB), indicating a mantle source characterized by MORB-like isotopic signatures. The low whole-rock water contents are attributed to lithospheric reheating resulting from asthenospheric upwelling during the Late Mesozoic–Early Cenozoic. Therefore, the lithosphere is predominantly composed of ancient Proterozoic residues, with localized contributions of younger asthenospheric material near deep faults. Full article

Rockfalls pose significant threats to infrastructure, transportation routes, and human safety in mountainous regions, making them a critical concern in natural hazard and risk management. Accurate prediction of rockfall behavior is essential for designing effective mitigation strategies. The normal coefficient of restitution (R_n) is a key kinematic parameter for modeling falling rock dynamics, specifically quantifying the energy retained after collision between a rock and a slope surface. While this parameter is not directly used in prevention design, it is crucial for predicting the movement and trajectory of falling rocks and can indirectly support the development of more effective hazard mitigation strategies. However, R_n is influenced by multiple factors, including slope angle, surface material, falling rock shape, and initial velocity. The interactions among these factors make a precise prediction of R_n particularly challenging. Existing theoretical and empirical formulas typically consider individual factors in isolation, often neglecting their interactions, which leads to significant discrepancies in the results. To address this gap, we conducted a series of laboratory physical model tests to investigate the interactions among highly sensitive controlling factors and improve the accuracy of R_n prediction. A self-designed release apparatus, coupled with a high-speed recording and analysis system, was used to capture full kinematic data during rockfall collisions on slopes. This study not only examined how the main controlling factors and their interactions affect R_n but also developed a multi-factor interaction regression model, which was verified using on-site test data. The results show that the effect of the main controlling factors decreases in the following order: falling rock shape, slope surface material, initial velocity, and slope angle. Considering that falling rock shape and slope surface material cannot be quantitatively evaluated, the shape factor (η) and material factor (A_slope) are proposed to represent two controlling factors, respectively. Specifically, increases in η, A_slope, initial velocity, and slope angle are negatively correlated with R_n. Highly significant interactions were observed among falling rock shape–slope surface material, falling rock shape–initial velocity, falling rock shape–slope angle, slope surface material–initial velocity, and falling rock shape–slope surface material–initial velocity. These interactions mitigate the R_n reduction, resulting in a weaker effect than the stacking effect of the individual factors. The phenomenon is primarily attributed to the fact that high-level η, A_slope, initial velocity, and slope angle diminish the effect of intersecting factors. Finally, a comparison of the multi-factor interaction model with on-site tests and empirical formulas revealed the accuracy of the proposed model. Full article

In the current excavation of water diversion tunnels, significant challenges such as water inrush, rockburst, and large deformations continue to persist. Consequently, research on the stability of the surrounding rock after tunnel excavation is of great scientific importance. To address the impact of groundwater on tunnel-surrounding rock deformation under complex geological conditions, this study utilizes a combination of field monitoring and numerical simulation. Specifically, the research simulates the excavation process under both groundwater and non-groundwater conditions. Systematically, it analyzes the deformation patterns of tunnel-surrounding rock under groundwater conditions. The findings reveal the following: (1) Settlement and excavation mileage exhibit a clear trend of “steep decline, gradual decline, stable,” both stabilizing around 35 m after the excavation reaches the monitoring cross-section. Changes in groundwater levels, whether rising or falling, can either accelerate or delay the point at which settlement stability is achieved. (2) The numerical simulation settlement curves closely align with the field monitoring curves, with simulated settlement values slightly exceeding the monitored results. However, the error rate between the two remains below 20%, indicating the reliability of the method. (3) Groundwater significantly impacts water-sensitive strata such as loess and sandstone, with maximum settlement values at the tunnel vault and ground surface under groundwater conditions being 2 to 3 times those observed in the absence of groundwater. This study provides a scientific basis for optimizing tunnel design and construction processes. Future research should focus on refining the numerical simulation model, by incorporating additional monitoring data for validation and enhancing the safety of tunnel construction. Full article

To address the challenge of repairing the damage to concrete box girder bridge piers on mountainous highways caused by falling rocks, this paper proposes an active underpinning technique that integrates a “井”-shaped cap system, graded preloading of the foundation, and synchronized beam body correction. The technique utilizes lateral beam preloading (to eliminate the inelastic deformation of the new pile foundation) and longitudinal beam connections (to form overall stiffness). The method involves building temporary and permanent support systems in stages. Through the two-stage temporary support system transition, the removal and in situ reconstruction of the old piers, a smooth transition from the pier–beam consolidation system to the basin-type bearing system is achieved while simultaneously performing precise correction of beam torsion. The structural safety during the construction process was verified through finite element simulations and dynamic monitoring. Monitoring results show that the beam torsion recovery effect is significant (maximum lift of 5.2 mm/settlement of 7.9 mm), and the pier strain (−54.5~−51.3 με) remains within a controllable range. Before the bridge was opened to traffic, vehicle load and impact load tests were conducted. The actual measured strength and vertical stiffness of the main beam structure meet the design requirements, with relative residual deformation less than 20%, indicating that the structure is in good, elastic working condition. The vehicle running and braking dynamic coefficients (μ = 0.058~0.171 and 0.103~0.163) are both lower than the theoretical value of 0.305. The study shows that this technique enables the rapid and safe repair of bridge piers and provides important references for similar engineering projects. Full article