Search Results (29)

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

As urban areas keep growing, there are higher requirements for the carrying capacity of traffic operations, and there are more and more curve incremental launching projects with complex construction conditions. This paper builds upon the walking incremental launching project of a small-curvature steel box girder in Xuchang City and has developed a detailed construction method and monitoring technology. Due to the bridge’s longitudinal gradient being designed as a two-way slope and falling under the category of a small-radius steel box girder, the front end of the main beam exhibits significant lateral deviation, and linear control is difficult. It is necessary to carry out stress and displacement monitoring of the whole process of construction of the curved steel box girder and the guide girder to guide the construction process. The stress conditions of the incremental launching pier and the settlement of the concrete substructure are also studied, and we analyze the stress and displacement characteristics. Firstly, the finite element tool MIDAS Civil is adopted to build a model for the construction. The five most unfavorable working conditions are selected from the entire incremental launch process to analyze the internal force and displacement state of the steel box girder bridge, which is and then compared with the site monitoring value. It is demonstrated by the outcomes that the internal force and deflection of the steel box girder and the guide girder are within the safe construction range, which ensures the security of the incremental launching construction. In the maximum cantilever condition, the guide girder experiences significant stress, but the maximum value is not observed during the maximum cantilever condition of the guide girder. Therefore, whole-process monitoring should be carried during construction to maintain safety measures and quality management. Full article

Astrogeodetic deflections of the vertical (DoVs) are close indicators of the slope of the geoid. Thus, DoVs observed along horizontal profiles may be integrated to create geoid undulation profiles. In this study, we collected DoV data in the Eastern Swiss Alps using a Swiss Digital Zenith Camera, the COmpact DIgital Astrometric Camera (CODIAC), and two total station-based QDaedalus systems. In the mountainous terrain of the Eastern Swiss Alps, the geoid profile was established at 15 benchmarks over a two-week period in June 2021. The elevation along the profile ranges from 1185 to 1800 m, with benchmark spacing ranging from 0.55 km to 2.10 km. The DoV, gravity, GNSS, and levelling measurements were conducted on these 15 benchmarks. The collected gravity data were primarily used for corrections of the DoV-based geoid profiles, accounting for variations in station height and the geoid-quasigeoid separation. The GNSS/levelling and DoV data were both used to compute geoid heights. These geoid heights are compared with the Swiss Geoid Model 2004 (CHGeo2004) and two global gravity field models (EGM2008 and XGM2019e). Our study demonstrates that absolute geoid heights derived from GNSS/leveling data achieve centimeter-level accuracy, underscoring the precision of this method. Comparisons with CHGeo2004 predictions reveal a strong correlation, closely aligning with both GNSS/leveling and DoV-derived results. Additionally, the differential geoid height analysis highlights localized variations in the geoid surface, further validating the robustness of CHGeo2004 in capturing fine-scale geoid heights. These findings confirm the reliability of both absolute and differential geoid height calculations for precise geoid modeling in complex mountainous terrains. Full article

In various analytical models, modeling the behavior of large-diameter monopiles and piles can be challenging due to these foundations with huge body sizes carrying mechanisms of lateral loads to the surrounding soils. In this paper, the transfer matrix method with the Timoshenko beam theory was used to modify the shear rotation of pile sections under different loading stages, including serviceability limit stages and the ultimate loading stage. In this transfer matrix method, a large-diameter pile is considered according to the Timoshenko beam theory, and the recurring variables in the matrix equation are replaced with constants to simplify the calculation steps. Two model test cases were used to verify the accuracy of the method. Then, a series of comparisons between the Timoshenko beam and the Euler–Bernoulli beam theories, with the relative pile–soil stiffness being equal to 0.15, 0.45, and 0.75, was conducted to investigate the differences in pile response after considering the shear deformation. The results show that the effect of shear deformation of large-diameter piles changes with different loading levels. The values of the pile deformation based on the Timoshenko beam theory divided by those of that based on the Euler–Bernoulli beam theory were in the range of 1.0 to 1.10, and they increased slightly with increasing loads, reaching their maximum value, and then rapidly decreased to 1.0 when close to the ultimate lateral load; the maximum value was influenced by the relative pile–soil stiffness. Furthermore, the ratio of the shear rotation of the pile section to the slope of the deflection curve was in the range of 1.0 to 1.10; these also showed similar but more moderate trends compared with the values of pile deformation based on the Timoshenko beam theory divided by those of that based on the Euler–Bernoulli beam theory. Full article

With the increasing demand for automation in agriculture, more and more researchers are exploring the application of digital twin in agricultural production. However, existing studies have predominantly focused on enhancing resource utilization efficiency and improving irrigation control systems in agricultural production through the implementation of digital twins. Unfortunately, there is a noticeable research gap when it comes to applying digital twins specifically to buried water conveyance pipelines within an agricultural irrigation infrastructure. Focusing on the long-term performance requirements of buried pipelines in agricultural irrigation and drainage, this study established a digital twin system for the industry of axial hollow-wall pipes with an outer diameter of 200 mm, specifically designed for this field of operation. The system was used to optimize the end-forming process of axial hollow-wall pipes, resulting in improved leak tightness under internal pressure and angular deflection of the pipes. The study suggests that the most effective method for the end-forming process of axial hollow-wall pipes is to heat the pipe for 60 s at the ambient temperature of 15 °C, with heating temperatures of 225 °C on both the inner and outer sides. Additionally, preheating the stamping equipment to 70 °C and controlling the cooling temperature, during pipe detachment, to between 35 °C and 45 °C is recommended. In terms of the leak tightness under internal pressure and angular deviation, the study found that increasing the thickness of the protruding end of the sealing ring to 16 mm, and shortening the chamfer length to 20 mm, while maintaining the same slope, can enhance the sealing effectiveness of the pipeline interface. The implementation of the digital twin system improves the production efficiency of the hollow pipe production line during the end-forming process, resulting in a yield rate of the pipe of up to 95% for qualified products. Moreover, the system provides intelligent closed-loop feedback which ensures the long-term operation and maintenance of the pipelines, making it easier to identify problems and implement design improvements. By doing so, it contributes to ensuring the long-term stability of related agricultural production. Full article

As a new type of retaining structure, lattice beams with tie-back anchor cables have been increasingly used in slope reinforcement and have achieved improved prevention effects. However, the simplified load distribution method (SLDM) at the node, which is the theoretical basis of internal force analysis for lattice beams, is not perfect at present. An alternative new load distribution method (NLDM) at the node based on the force method for the lattice beam was therefore introduced in this paper. Taking into account the loads acting on other nodes of the beams in both directions and according to the static equilibrium condition and deformation compatibility condition at the nodes, NLDM assigns the loads acting on the nodes to the cross beams and vertical beams, respectively, by constructing and solving a system of linear equations. In order to verify the superiority of NLDM, a case of slope reinforced by a lattice beam was introduced in this paper, and the load distribution of the nodes under the design condition was carried out based on both methods. Then, the deflections at the nodes of the lattice beam resting on the Winkler foundation, loaded with the known loads, were analyzed by the superposition method. The results of the deformation analysis showed that the deflections at the same nodes of the beams in both directions based on NLDM were almost equal, thus demonstrating the superiority of NLDM in terms of deformation compatibility. In addition, a comparative analysis of the theoretical bending moments of the lattice beam under the design and the actual working conditions based on both methods was also carried out. The results of the bending moment analysis showed that the bending moments of the cross beam differed significantly in the middle third of the beam length, while the bending moments of the vertical beams differed significantly at the beam sections where the maximum bending moments are located, and the theoretical bending moments under the actual working condition were in relatively good agreement with the measured values. Consequently, NLDM for the lattice beam was self-consistent in terms of the deformation compatibility at the node, and therefore the introduction of this new method provides an important theoretical basis for the accurate internal force analysis of lattice beams. Full article

The physical and mechanical properties of the reservoir bank slope deteriorate under the fluctuation of water level, causing bank debonding and slippage, which can produce different degrees of damage to the bridge foundation, piers, and superstructure, a condition that is difficult to treat. In this paper, for a Yangtze River Bridge bank slope instability problem in the Three Gorges reservoir area, a numerical model of the bank slope and bridge was established using the finite element-SPH conversion coupling algorithm, and the pile pier damage development law and damage mode (deformation and stress–strain curves of the bank slope and pile foundation) were obtained according to the geological conditions of the bridge location. Additionally, combined with the characteristics of bank destabilization in the reservoir area of the Three Gorges Yangtze River Bridge, landslide management is proposed by using soil drainage and anti-slip pile reinforcement measures. In addition, for the characteristics of bridge pier deflection, a comprehensive deflection correction reinforcement method of pushing deflection correction, adding pile foundation, expanding pile bearing, and increasing pier cross-sectional area is proposed, so as to provide a theoretical basis for the prevention and control of reservoir bank landslides, the service life of pile structure, and the disposal of diseases. Full article

In seasonally frozen regions, highway tunnels are prone to shallow buried bias pressures near the inlet/outlet, which leads to highway tunnels not only bearing asymmetric loads, but also facing the threat of extreme weather. However, there is still no clear understanding of the temperature field for topographically biased tunnel in seasonally frozen regions at present. Taking the Huitougou tunnel of Hegang-Dalian expressway as the object, this paper uses on-site monitoring, theoretical analysis, and numerical simulation to study the distribution law and influence factors of temperature field for topographically biased tunnel in seasonally frozen regions. The numerical results of the temperature field are in good agreement with the on-site monitoring data, which verified the accuracy of this numerical model based on the aerodynamic principle, turbulence model, and wall function method. Meanwhile, the effect of different slope angle and overburden thickness on the temperature field of the tunnel is further analyzed. It is found that when the slope angle increases, the temperature field in the tunnel surrounding rock changes accordingly. The connecting area between the surface and the tunnel temperature field is deflected from arch crown to the arch shoulder of the tunnel, resulting in a large change in the temperature of the shallow buried side, while minor change in the temperature of the deep buried side. The freezing depth of surrounding rock decreases with the rising slope angle. As the overburden thickness gradually increases, the temperature field of the surface surrounding rock and the tunnel surrounding rock gradually change from mutual influence to non-influence. When the overburden thickness exceeds 15 m, a “isolated temperature zone” appears in the middle with a temperature of 6~7 °C, the temperature field of the tunnel surrounding rock is basically not affected by the surface air temperature. These results can provide important theoretical and engineering guidance for the evaluation, construction, and maintenance of tunnel engineering in seasonally frozen regions. Full article

In this study, the slope deflection method was presented for structures made of small-scaled axially functionally graded beams with a variable cross section within the scope of nonlocal elasticity theory. The small-scale effect between individual atoms cannot be neglected when the structures are small in size. Therefore, the theory of nonlocal elasticity is used throughout. The stiffness coefficients and fixed-end moments are calculated using the method of initial values. With this method, the solution of the differential equation system is reduced to the solution of the linear equation system. The given transfer matrix is unique and the problem can be easily solved for any end condition and loading. In this problem, double integrals occur in terms of the transfer matrix. However, this form is not suitable for numerical calculations. With the help of Cauchy’s repeated integration formula, the transfer matrix is given in terms of single integrals. The analytical or numerical calculation of single integrals is easier than the numerical or analytical calculation of double integrals. It is demonstrated that the nonlocal effect plays an important role in the fixed-end moments of small-scaled beams. Full article

A p-y curve method of pile near cohesionless soil slope under reversed lateral load is proposed. This method takes into account the failure mode of soil around the pile under reversed lateral load and the interaction mode between pile and soil, and derives the ultimate soil resistance of the pile. Considering the change of the original stress state of soil due to the lateral deflection of the pile foundation, the influence of the relative density, the initial mean effective stress and the lateral deflection of pile foundation on the internal friction angle of the sand is evaluated to further accurately calculate the soil resistance value at each depth. The prediction results of this method are well verified by comparing with the FE results and centrifuge test results. Finally, the influence of the process of lateral deflection of pile on the strength state of soil around the pile and the bearing capacity of pile is studied. Full article

The design guidelines available in building codes for steel and fibre reinforced polymer (FRP) reinforced concrete (RC) beams have been developed on the basis of empirical models. While these models are successfully used for practical purposes, they require continuous improvements with more experimental data. This paper aims to develop a general mathematical model derived from the intrinsic material properties of concrete and certain reinforcements to analyse the bending behaviour of reinforced concrete beams. The proposed model takes into account the effects of non-linearity and ductility on the real behaviour of concrete under compression as well as the concrete tension stiffening. The model focused on analysing the flexural behaviour of rectangular steel, FRP and hybrid FRP–steel RC beams, using the moment–curvature relationship. A general static equilibrium equation was developed and mathematically solved with precise methods to establish a moment–curvature relationship. The effective flexural stiffness (EFS) is therefore calculated by the slope of the moment–curvature diagram, and then the load–deflection response is immediately deduced according to the loading conditions. The present model results were compared with numerous test data reported by various researchers. The comparisons reveal a good accuracy for predicting the EFS and load–deflection response for either steel, FRP, and hybrid reinforced concrete beams, with an error average less than 10%. Full article

Three-dimensional (3D) simulations using the smoothed particle hydrodynamics (SPH) method were performed for smooth and stepped spillways with converging walls, in order to evaluate the influence of the wall deflection and the step macro-roughness on the main non-aerated flow properties. The simulations encompassed a 1V:2H sloping spillway, wall convergence angles of 9.9° and 19.3°, and discharges corresponding to skimming flow regime, in the stepped chute. The overall development of the experimental data on flow depths, velocity profiles, and standing wave widths was generally well predicted by the numerical simulations. However, larger deviations in flow depths and velocities were observed close to the upstream end of the chute and close to the pseudo-bottom of the stepped invert, respectively. The results showed that the height and width of the standing waves were significantly influenced by the wall convergence angle and by the macro-roughness of the invert, increasing with a larger wall deflection, and attenuated on the stepped chute. The numerical velocity and vorticity fields, along with the 3D recirculating vortices on the stepped invert, were in line with recent findings on constant width chutes. Full article

The nonlinear bending of the sandwich plates with graphene nanoplatelets (GPLs) reinforced porous composite (GNRPC) core and two metal skins subjected to different boundary conditions and various loads, such as the concentrated load at the center, linear loads with different slopes passing through the center, linear eccentric loads, uniform loads, and trapezoidal loads, has been presented. The popular four-unknown refined theory accounting for the thickness stretching effects has been employed to model the mechanics of the sandwich plates. The governing equations have been derived from the nonlinear Von Karman strain–displacement relationship and principle of virtual work with subsequent solution by employing the classical finite element method in combination with the Newton downhill method. The convergence of the numerical results has been checked. The accuracy and efficiency of the theory have been confirmed by comparing the obtained results with those available in the literature. Furthermore, a parametric study has been carried out to analyze the effects of load type, boundary conditions, porosity coefficient, GPLs weight fraction, GPLs geometry, and concentrated load radius on the nonlinear central bending deflections of the sandwich plates. In addition, the numerical results reveal that the adopted higher order theory can significantly improve the simulation of the transverse deflection in the thickness direction. Full article

This study presents the experimental, numerical analysis, and dynamic impact analysis of a building collapse caused by a rainfall-induced landslide (vertical cut slope failure) on 15 August 2018, in Peringavu, Kerala, India, which resulted in the death of nine people. The volume of 1500 m³ soil-applied lateral thrust force on the building’s rear side led to its demolition. The study includes extensive geotechnical characterization. General limit equilibrium and finite element methods were used in the numerical analysis. The infiltration analysis involved a rainfall pattern of low, moderate, and higher intensities on the slope. The study involved a two-stage analysis. Firstly, the analysis of the vertical cut slope with the application rainfall intensities, and second, the analysis of the building under the dynamic impact of the landslide. As a result of the study, the failure mechanism of the vertical cut during intense rainfall and triggering factors were evaluated. The dynamic impact analysis was carried out to examine the effects of the impact of the landslide debris on the building and the performance of the building under the impact load. The load-bearing walls experienced high-intensity impact force developed by the landslide, resulting in the lateral displacement of 170 mm and differential settlement of 92 mm, which led to the building’s demolition. The flexural failures, excessive deflections, bending moments, foundation settlements, and displacement of structural elements were studied. Full article

This study aims to investigate the one-way cyclic lateral responses of piles in sloping ground by means of experimental and theoretical analyses. For this purpose, a series of laboratory model experiments were performed for different cases of cycle number, load amplitude, and slope angle, and lateral static loading tests on both level ground and sloping ground were conducted for comparison. Based on these experimental observations, the effects of cycle number, load amplitude, and slope angle on the pile head deflection and the profiles of bending moment and subgrade reaction are discussed. The pile deflection profile is difficult to measure directly owing to the restriction of experimental conditions, and thus a supplementary finite beam element method (FBEM) is provided to compensate for this deficiency. The comparisons between experimental and theoretical results demonstrate that the FBEM can well predict the pile responses in sloping ground, either under one-way cyclic lateral loading or lateral static loading. Full article