Search Results (80)

Squeezed branch piles, originally developed for building and bridge foundations, have been downsized and deployed at larger pile spacing for reinforcing embankments over soft soils. However, the working mechanism of squeezed branch pile-supported embankments remains unclear. In this study, a three-dimensional numerical model of this embankment was established based on field tests. The analyses consider different pile types (squeezed branch piles and straight piles) and pile-head structures (beam-type cap and plate-type cap). These concrete components were modeled utilizing an advanced concrete model, which captures the strain-softening/hardening and yielding behavior. Simulation results show that squeezed branch piles provide better settlement control in the subsoil beneath the embankment than straight piles for the studied cases. The beam-type cap with squeezed branch piles behaves as a pile-beam foundation that reduces maximum settlement by around 38% compared to that of the plate-type cap, while the plate-type cap system functions as a composite foundation that enhances surcharge capacity by about 35–40%. The instability of the embankment is driven by tensile failure in concrete: The beam-type cap leads to a localized failure along the ground beam, and the plate-type cap system induces a progressive failure centered on the squeezed branch piles. Within the plate-type cap, the dimensions of the pile-head plate significantly influence settlement control and the stability of the embankment in soft soil. Full article

During the high-intensity mining of shallow-buried thick coal seams, the formation of a water-conducting fracture zone within the overburden is a primary cause of damage to the groundwater system. To address the challenge of balancing efficiency and cost in traditional water-retaining mining methods, this study proposes and validates a trapezoidal strip filling mining technology based on the “span reduction effect”. By developing a mechanical model of a four-sided simply supported thin plate representing the key layer, the fundamental mechanism of the filling body was elucidated. This mechanism involves the active adjustment of the support boundary, which effectively reduces the force span of the key layer. Furthermore, leveraging the fourth-power relationship (w ∝ a⁴) between deflection and span, the bending deformation of the overburden rock is exponentially mitigated. This study employs a four-tiered integrated verification system comprising theoretical modeling, physical simulation, numerical simulation, and engineering field testing: First, theoretical calculations indicate that reducing the effective span of the key layer by 40% can decrease its maximum deflection by 87%. Second, large-scale physical similarity simulations predict that implementing this filling method can significantly control the height of the water-conducting fracture zone, reducing it from 94 m under the collapse method to 58 m, which corresponds to a 45.5% reduction in surface settlement. Third, FLAC^3D numerical simulations further elucidated the mechanical mechanism by which the backfill system transforms stress distribution from “coal pillar-dominated bearing capacity” to “synergistic bearing capacity of backfill and coal pillars”. Shear failure in the critical layer was suppressed, and the development height of the plastic zone was restricted to approximately 54 m, showing high consistency with physical simulation results. Finally, actual measurements of water injection through the inverted hole underground provide direct evidence: The heights of the water-conducting fracture zones in the filling working face and the collapse working face are 59 m and 93 m, respectively, reflecting a reduction of 36.6%. Based on the consistency between measured and simulated results, the numerical model employed in this study has been effectively validated. Research indicates that employing trapezoidal strip filling technology based on principal stress dynamics regulation can effectively promote a shift in the failure mode of the overlying critical layer from “fracture–conduction” to “bending–subsidence”. This mechanism provides a clear mechanical explanation and predictable design basis for the green mining of shallow coal seams. Full article

Aiming at the wind-blown snow disasters plaguing tunnel portals along the China-Tajikistan Highway Phase II Project, this study optimizes the protective parameters of wind deflectors through numerical simulation to improve the disaster prevention efficiency of tunnel portals in alpine mountainous areas. Three core control parameters of wind deflectors, namely horizontal distance from the tunnel portal (L), plate inclination angle (β), and top installation height (h), were selected as the research objects. Single-factor numerical simulation scenarios were designed for each parameter, and an L9(3³) orthogonal test was further adopted to formulate 9 groups of multi-parameter combination scenarios, with the snow phase volume fraction at 35 m on the leeward side of the tunnel portal set as the core evaluation index. A computational fluid dynamics (CFD) model was established to systematically investigate the influence laws of each parameter on the wind field structure and snow drift deposition characteristics at tunnel portals and clarify the flow field response rules under different parameter configurations. Single-factor simulation results show that the wind deflector exerts distinct regulatory effects on the wind-snow flow field with different parameter settings: when L = 6 m, the disturbance zone of the wind deflector precisely covers the main wind flow development area in front of the tunnel portal, which effectively lifts the main incoming flow path, compresses the recirculation zone (length reduced from 45.8 m to 22.3 m), and reduces the settlement of snow particles, achieving the optimal comprehensive prevention effect; when β = 60°, the leeward wind speed at the tunnel portal is significantly increased to 10–12 m/s (from below 10 m/s), which effectively promotes the transport of snow particles and mitigates the accumulation risk, being the optimal inclination angle; when h = 2 m, the wind speed on both the windward and leeward sides of the tunnel portal is significantly improved, and the snow accumulation risk at the portal reaches the minimum. Orthogonal test results further quantify the influence degree of each parameter on the snow prevention effect, revealing that the horizontal distance from the tunnel portal is the most significant influencing factor. The optimal parameter combination of the wind deflector is determined as L = 6 m, β = 60°, and h = 2 m. Under this optimal combination, the snow phase volume fraction at 35 m on the leeward side of the tunnel portal is 0.0505, a 12.3% reduction compared with the non-deflector condition; the high-concentration snow accumulation zone is shifted 25 m leeward, and the high-value snow phase volume fraction area (>0.06) disappears completely, which can effectively alleviate the adverse impact of wind-blown snow disasters on the normal operation of tunnel portals. The research results reveal the regulation mechanism of wind deflector parameters on the wind-snow flow field at alpine tunnel portals and determine the optimal protective parameter combination, which can provide important theoretical reference and technical support for the prevention and control of wind-blown snow disasters at tunnel portals in similar alpine mountainous areas. Full article

Marine biofouling significantly impacts vessel operational efficiency, with mussel species being particularly problematic due to their rapid settlement on biofilm-covered surfaces. This pilot study presents the first explicit test of whether ultrasonic treatment can disrupt the biofilm–larva interaction pathway that facilitates mussel settlement. The study evaluated ultrasonic treatment (28 kHz) as a preventive antifouling strategy targeting the mixed microbial biofilm-mediated settlement pathway of Mytilus edulis. A controlled laboratory experiment compared settlement rates on biofilm-conditioned (2.5-week mixed microbial biofilm development) and unconditioned steel plates with and without ultrasonic treatment. Under control conditions, biofilm presence increased mussel settlement odds by 49-fold (p < 0.001). Ultrasonic treatment eliminated this biofilm enhancement, maintaining settlement at baseline levels (odds ratio: 1.3, p = 0.84). The mechanism remains unclear but may involve biofilm disruption, larval behavioral avoidance, or interference with chemical cues. While limited replication (n = 2, temporal replicates, one tank per treatment per replicate) constrains statistical power and inference, the large effect size and consistency across replicates warrant additional investigation. If confirmed by increased replication and mechanistic studies, ultrasonic treatment could provide sustainable antifouling protection without chemical discharge. Full article

The large-scale generation and disposal of fly ash pose significant environmental concerns, highlighting the need for its sustainable reuse in geotechnical applications. This study investigates the performance of fly ash blended with polypropylene fiber as an infill material in geocell-reinforced sand beds to enhance bearing capacity and reduce settlement. Plate load tests were conducted in the laboratory by varying geocell mattress height, cement content, fiber content, and curing period. The results showed that polypropylene fibers improved the shear strength of the fly ash mix. Increasing the geocell mattress height from 0.5B to 1B enhanced the ultimate bearing pressure of a sand bed by 3.4×. At a mattress height of 1B, an improvement factor of 13.18 was achieved at a settlement (s/B) of 12.5%, and this improvement is attributed to confinement provided by the geocell because of enhanced load distribution. Fly ash mix with 6% polypropylene fiber and 5% cement yielded an ultimate bearing pressure of 460 kPa after 3 days of curing, which was 6.9× higher than that of an unreinforced sand bed. These findings demonstrate that fiber-reinforced fly ash is a sustainable and efficient infill material for geocell mattresses, offering both environmental benefits and improved geotechnical performance. Full article

Computational modeling offers a cost-effective approach to exploring complex geotechnical behavior. This study uses PLAXIS 2D finite element software to simulate nailed soil slopes under plane strain conditions, with models calibrated against laboratory-scale experiments involving a sand-filled Perspex box, steel nail reinforcements, and a rigid foundation. The soil mass, structural elements, and reinforcements are modeled using fifteen-node triangular elements, five-node plate elements, and two-node elastic spring elements, respectively. In this paper, parametric studies evaluate the influence of slope angles, mesh density, domain dimensions, constitutive models, and reinforcement configurations. Both prototype-scale and 3D-approximated models are included to assess scale effects and spatial behavior. The results highlight the significant impact of model size and material behavior, particularly when using the Hardening Soil model and its small-strain extension. Reinforcement optimization, including nail length reduction strategies, demonstrates the potential for maintaining slope stability while improving material efficiency. Validation against experimental data confirms that the numerical models accurately capture deformation patterns and internal stress development across different construction and loading phases. This study observed that the Hardening Soil (small-strain) material model significantly improved slope performance by reducing settlements and better capturing stress behavior, especially for steep slopes. Optimized redistribution of nail lengths across the slope depth enhanced stability while reducing reinforcement usage, demonstrating a cost-effective alternative to uniform configurations. The findings offer practical guidance for optimizing nailed slope stabilization in sandy soils, supporting safer and more economical geotechnical design for real-world applications. Full article

To improve fine particle retention in cyclone clarifiers for mine water treatment, we developed three baffle-structured cyclone clarifiers based on the traditional design: flat-baffle cyclone clarifier, convex-baffle cyclone clarifier, and concave-baffle cyclone clarifier. Using numerical simulation, a comparative analysis was conducted on the differences in flow field characteristics and particle separation performance between the traditional cyclone clarifier and the three types of baffle-structured cyclone clarifiers. The convex-baffle cyclone clarifier showed the highest pressure drop. At Section II-II, low tangential velocity minimized internal swirl, while Section I-I exhibited high axial velocity near the wall. The low upward axial velocity in the central region of Section II-II enhanced fine particle settling. The convex baffle also promoted uniform streamlines and efficient space utilization. The concave-baffle cyclone clarifier exhibited a larger flow angle relative to the baffle than the flat-baffle cyclone clarifier, causing stronger impingement and turbulence that transported particles to the overflow outlet. In contrast, the convex-baffle cyclone clarifier’s smaller flow angle yielded weaker impingement and more stable flow, reducing particle escape. Simulations confirmed that baffle-structured cyclone clarifiers improve particle removal. The removal efficiency of the convex-baffle cyclone clarifier reaches 78.19%, representing a 5.22% improvement compared to the traditional cyclone clarifier. Furthermore, the convex-baffle cyclone clarifier demonstrated the most effective removal of 5 μm particles compared with both the flat-baffle and concave-baffle cyclone clarifier. Full article

Mytilus coruscus, a commercially important mariculture mussel in China, has shown a marked decline in larval settlement and metamorphosis over the past decade, a trend often linked to environmental degradation and resource depletion. Numerous studies have identified bacterial biofilms as key modulators of mussel larval settlement. To investigate this, we deployed PVC plates in situ within aquaculture zones near Shengsi (Zhoushan, Zhejiang) and Lianjiang (Fuzhou, Fujian). After natural biofilm colonization on the plates, juvenile M. coruscus were introduced to assess settlement rates. The attached juveniles were homogenized, leading to the isolation of four dominant bacterial strains: Pseudomonas sp. LJBF001, Vibrio sp. LJBF002, Pseudomonas sp. LJBF003 and Bacillus sp. LJBF004. Compared to control PVC plates, natural biofilms significantly promoted juvenile settlement, with the Lianjiang (LJ) group reaching up to >29% under our assay conditions. In contrast, monospecific biofilms prepared from these isolates did not significantly increase larval metamorphosis; the numerically highest response (LJBF004) reached ~9% and was not significant versus the control. These contrasting outcomes are consistent with a threshold–multi-cue synergy mechanism, whereby cue diversity and partial redundancy in natural biofilms favour threshold crossing, while restricted cue sets in single-strain films often fall short. Guided by this framework, priority next steps include testing c-di-GMP delivery (soluble and via OMVs), probing EPS structure–function and EPS–OMV/LPS–free-fatty-acid blends alongside minimal multi-strain consortia, and adopting stage-gated assays with time-to-event endpoints and effect-size/CI reporting. Full article

Focusing on the issues of severe mining pressure and discontinuous surface deformation caused by the large-scale mining of multiple coal seams, and taking into account the research background of Shigetai Coal Mine in Shendong Mining Area, this study adopts physical similarity simulation, theoretical analysis, and on-site verification methods to carry out research on rock migration, stress evolution, and overlying rock fracture mechanism at shallow burial depths and in multiple-coal-seam mining. The research results indicate that as the working face advances, the overlying rock layers break layer by layer, and the intact rock mass on the outer side of the main fracture forms an arched structure and expands outward, showing a pattern of layer-by-layer breaking of the overlying rock and slow settlement of the loose layer. The stress of the coal pillars on both sides in front of and behind the workplace shows an increasing trend followed by a decreasing trend before and after direct top fracture. The stress on the bottom plate of the goaf increases step by step with the collapse of the overlying rock layer, and its increment is similar to the gravity of the collapsed rock layer. When mining multiple coal seams, when the fissures in the overlying strata of the current coal seam penetrate to the upper coal seam, the stress in this coal seam suddenly increases, and the pressure relief effect of the upper coal seam is significant. Based on the above laws, three equilibrium structural models of overlying strata were established, and the maximum tensile stress and maximum shear stress yield strength criteria were used as stability criteria for overlying strata structures. The evolution mechanism of mining damage caused by layer-by-layer fracturing and the upward propagation of overlying strata was revealed. Finally, the analysis of the hydraulic support working resistance during the backfilling of the 31,305 working face in Shigetai Coal Mine confirmed the accuracy of the similarity simulation and theoretical model. The above research can provide support for key theoretical and technological research on underground mine safety production, aquifer protection, surface ecological restoration, and source loss reduction and control. Full article

One of the most common issues encountered in the rehabilitation of timber-structured buildings is the crushing of elements subjected to compression perpendicular to the grain. This crushing results in differential settlements that decrease comfort and, in some cases, compromise the habitability of the building. This study analyzed a reinforcement method involving the lateral confinement of timber members using two metallic side plates. Experimental tests were conducted with various configurations of the bolts used to fix the plates. In addition, several finite element models were developed and validated to extend the scope of the analysis virtually. An initial reinforcement proposal was examined, in which the metal plates were allowed to move vertically with the wood’s deformation. This setup achieved only a 26% reduction in deformation. Subsequently, an enhanced reinforcement system was tested, wherein the plates were anchored to the lower vertical stud, preventing their vertical movement. This configuration significantly enhanced performance, achieving maximum deformation reductions of up to 53%. Finally, in the improved reinforcement system, the load distribution among the bolts was analyzed to support their structural design. Full article

Urban rail transit networks’ rapid expansions have led to increasing intersections between existing and new lines, particularly in dense urban areas where new stations must underpass existing infrastructure at zero distance. Deformation controls during construction are critical for maintaining the operational safety of existing stations, especially in soft soil conditions where construction-induced settlement poses significant risks to structural integrity. This study systematically investigates the influence mechanisms of different construction schemes on base plate deformation when an open-top UBIT (underground bundle composite pipe integrated by transverse pre-stressing) underpasses existing stations. Through precise numerical simulation using PLAXIS 3D, the research comparatively analyzed the effects of 12 pipe jacking sequences, 3 pre-stress levels (1116 MPa, 1395 MPa, 1674 MPa), and 3 soil chamber excavation schemes, revealing the mechanisms between the deformation evolution and soil unloading effects. The continuous jacking strategy of adjacent pipes forms an efficient support structure, limiting maximum settlement to 5.2 mm. Medium pre-stress level (1395 MPa) produces a balanced deformation pattern that optimizes structural performance, while excavating side chambers before the central chamber effectively utilizes soil unloading effects, achieving controlled settlement distribution with maximum values of −7.2 mm. The optimal construction combination demonstrates effective deformation control, ensuring the operational safety of existing station structures. These findings enable safer and more efficient urban underpassing construction. Full article

Construction sites with deep soft deposits usually experience significant consolidation settlement that can compromise structural integrity if not properly monitored. Conventional methods, such as settlement plates, are limited by high costs and sparse spatial coverage, which leaves areas unmonitored and vulnerable to unexpected settlement. Therefore, this study develops an integrated UAV LiDAR monitoring framework that optimizes data preprocessing and introduces a novel timeseries settlement correction and interpolation technique for staged surcharge loading. Using UAV LiDAR data acquired at biweekly intervals from May 2021 to March 2022 at Busan Newport, high-quality digital elevation models were generated through optimal preprocessing. We are the first to evaluate the spatial representativeness of consolidation settlement at multiple section sizes (10 m × 10 m, 50 m × 50 m, and 100 m × 100 m) using high-resolution LiDAR, revealing that larger section sizes produce greater spatial variability and prediction error. Moreover, we demonstrate that at least seven biweekly UAV LiDAR surveys are essential to reliably capture early-stage settlement behaviors, providing a practical guideline for monitoring campaigns. These findings show that the proposed UAV LiDAR framework can deliver valuable insights for managing settlement in marine and soft ground construction projects. Full article

Surface settlement prediction is crucial to assess the safety of subway station construction. To overcome challenges such as missing on-site settlement data and a limited number of monitoring points, this study proposes a composite prediction model that integrates finite element analysis, a time-series interval GA-BP neural network, and variational mode decomposition (VMD) techniques. Using the Dongba-zhongjie Station in Beijing Subway Line 3 as a case study, surface settlement predictions were made for both typical monitoring points and randomly selected feature points throughout the construction period, followed by validation. The experimental results show that the root mean square error (RMSE) of the finite element model is 15.77%, confirming the model’s effectiveness. As excavation progressed through the second underground floor and bottom plate, the settlement at the maximum settlement point began to rebound, and the structure tended to stabilize. At this stage, construction of the comprehensive utility tunnel above the station can proceed concurrently. Full article

In an effort to monitor ascidian recruitment in mussel aquaculture facilities, a series of settlement plates (20 × 20 cm) were placed in a mussel farm located in the Amvrakikos Gulf (Ionian Sea). The plates were vertically deployed on floating facilities in the water column at regular intervals (depths of 0.2 m, 1.5 m, and 3 m) to monitor the settlement and proliferation of ascidians. Furthermore, measurements of seawater physicochemical parameters such as temperature, salinity, dissolved oxygen, and chlorophyll-a concentration were conducted together with the record of ascidian species in each sampling from January 2021 to November 2021. The correlation of these parameters with ascidian species provides information on their effect on the periodicity of ascidians’ recruitment. The results demonstrated a significant correlation between ascidian presence and water temperature. The potential influence of other important environmental parameters such as chlorophyll-a was not revealed, likely due to the limited number of values and samples included in the analyses. While increased chlorophyll levels, reflecting increased primary productivity or nutrient availability, are associated with increased growth and reproduction of all ascidian species, the effect of temperature was more potent and species-specific. Ciona robusta, Styela plicata, Microcosmus squamiger, and Phallusia mammillata were mainly detected at temperatures below 25 °C, whereas Clavelina oblonga was prevalent at temperatures above 25 °C. The absence of most ascidians at temperatures above 25 °C was possibly attributed to decreased settlement success and to the increased competition from C. oblonga at higher temperatures. The deployment of settlement plates in correlation with seawater physiochemical parameters can provide valuable data on ascidian settlement dynamics and support the development of targeted management practices for biofouling control. Full article

Accurate inversion of geotechnical parameters is essential for assessing foundation-bearing capacity and stability, which directly impact structural safety and serviceability. Accurate prediction of load settlement behavior is crucial to prevent overdesign and underperformance, ensuring that foundations support anticipated loads without excessive deformation or failure. This paper presents an integrated optimization system combining ABAQUS (2022), Python (PyCharm21.3.3), and MATLAB (2022b) software, based on the Duncan–Chang (DC) model, for inversion of key geotechnical parameters. The ABAQUS UMAT subroutine customizes the DC model, facilitating its application in finite element simulations for soil–structure interaction analysis. To improve the optimization process, an adaptive genetic algorithm that dynamically adjusts crossover and mutation rates, thereby improving solution searches and parameter space exploration, is implemented. Key parameters of the DC model—the initial tangent stiffness (K) and nonlinear deformation characteristics (n) of soil—are inverted. The accuracy of this inversion is validated through comparisons with experimental pressure–settlement curves obtained from indoor bearing plate tests. Therefore, this optimization system effectively integrates intelligent algorithms with finite element analysis, serving as a reliable tool for precise geotechnical parameter inversion, with potential for improving foundation design accuracy, optimizing soil–structure interaction predictions, and improving the overall stability and safety of geotechnical structures. Full article