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In this work, we propose a variation of Miura origami which, different from the existing out-of-plane bending Miura origami, has an in-plane bent configuration due to its graded crease pattern. By combining with the one-way shape memory alloy spring, we show that the proposed graded Miura origami can serve as a smart actuator and can be applied to drive crawling robots or grippers. First, we constructed a physical model of the graded Miura origami, from which a curvature-programmable geometric equation is proposed. Then, in addition to providing a mechanical model that can capture the mechanical behavior of the initial force–displacement relationship of the curved beam, we show that the proposed curved origami has a different mechanical behavior compared to the corresponding simple flexible arch, specifically if realized by silicon rubbers. By arranging anisotropic friction to the feet, the origami robot can crawl with an omega-elongation/compression motion like an inchworm. With a closed-loop current source control system using a high-frequency pulse width modulation-based topology, where the strain state of the arched origami is detected by a demodulator-free fiber Bragg grating sensor, the average speed of the origami crawling robot can reach 2.72 mm/s. In addition, by arranging three graded Miura origami, a gripper capable of lifting a weight of 518.5 g can be formed, where the carried load is over 4.5 times its own weight. [ABSTRACT FROM AUTHOR]

Machine learning techniques are potent tools to predict structural failures and forecast future failure patterns. They can provide insights that are not immediately recognizable to human operators, and hence, enhance the maintenance decision-making process, leading to better safety and longevity of structures. This research employed a genetic algorithm based on an identification technique to estimate the location and depth of cracks in circular arches. The arches were made of homogeneous material and had a rectangular cross-section. The study adopted two different procedures for detecting cracks in the circular arches. The first method used natural frequency contours represented in a three-dimensional plot to identify the location and depth of cracks by intersecting a set of natural frequency contours. The second procedure utilized the regression method and an optimization technique to minimize the cost function objective function and determine the crack parameters. The influences of crack location and depth on the vibrational behavior of cracked arches were presented and discussed. Similarly, the results indicate a high level of consistency between the two techniques in predicting both crack size and location. [ABSTRACT FROM AUTHOR]

The dynamic performance of a multi-column removal frame (MCRF) suffering from accidental impacts and uniform superstructure loads has largely been neglected in previous studies. To this end, a one-fifth scaled test model was set up to study the MCRF failure state and collapse mechanism. A numerical model was established and validated according to the collapse experiment. Parametric studies were conducted to investigate the effect of the impact height, heaped load (static uniform pressure on the slab), and frame storey on the MCRF dynamic response. The results indicated that: (i) the tension membrane, compressive arch and catenary effect were the main anti-collapse mechanisms in MCRF structures; (ii) according to the peak impact force under the increased collapse impact height (1.5 ∼ 2.5 m), a stronger local response and a slightly enhanced dynamic performance were successively presented on the hammer–concrete interaction; (iii) when the heaped load was increased, the structural plastic deformation capacity provided by the catenary action was better than that given by the compressive arch effect; (iv) the transient impact interaction was almost independent of the frame storey, but the MCRF anti-collapse performance was greatly affected by it. Finally, a collapse prediction method was given to evaluate the ultimate anti-collapse capacity of MCRF structures. [ABSTRACT FROM AUTHOR]

Previous research on seismic response analysis of dams primarily treated earthquakes as deterministic events; only a few studies on arch dams have explored earthquakes as random processes. This study introduces a three-dimensional seismic analysis of the Morrow Point arch dam, considering fully correlated random ground motion. The random ground excitation is characterized by the power spectral density function (PSDF) of the Kern County earthquake, for which the response time history is available. The spectral analysis technique describes the PSDF of the dam's response using the desired transfer function derived from Abaqus software. The analysis method is similar to that employed in finding the PSDF of the response of offshore structures from a given wave spectrum (PSDF). The method is validated by confirming the results of the proposed method with those of modal spectral analysis for empty dams and those of the time history analysis of the full reservoir dam. The results from the numerical study show that (1) the PSDF of responses obtained by modal spectral analysis using the first ten modes of the dam matches with those obtained by the direct analysis using transfer functions for the empty dam; and (2) mean peak arch stresses increases along the height of the dam from base to top, whereas mean peak cantilever stresses decreases; further, the mean peak arch stresses are less than the mean peak cantilever stresses at the base. [ABSTRACT FROM AUTHOR]

Translation abstract Wind‐induced vibrations on the hangers of the ÖBB‐RheinbrückeThe ÖBB‐Rheinbrücke near Lustenau is a new type of steel‐concrete composite arch structure with a span of 102 m. The main supporting structure is a Langer's beam with twelve round steel hangers on each side of the bridge, each 100 mm in diameter, with a maximum hanger length of 18.9 m. In arch bridges of this type with steel hangers, wind‐induced hanger vibrations can cause high‐frequency, high‐amplitude stress fluctuations in the hangers and their connections. This can be problematic from a fatigue point of view. After completion of the bridge, extensive monitoring was carried out as planned with the aim of obtaining information about the hanger vibrations that occur and the resulting damage to the material in order to determine whether vibration‐reducing measures need to be taken. In the course of monitoring and evaluation, it was found that wind‐induced hanger vibrations can cause fatigue‐relevant stress ranges to occur. This article presents the effects of two different physical phenomena, such as vortex‐excited transverse vibrations and rain‐wind‐induced vibrations, on the service life of the structure, as well as vibration‐reducing measures that help to mitigate these effects. [ABSTRACT FROM AUTHOR]

A rigid block model with elasto‐plastic softening interfaces is developed for nonlinear static analysis of masonry structures subject to monotonic loading. Cracking, crushing, and shear failures are taken into account at interfaces, following a simple micro‐modeling approach. An optimization‐based formulation is used for the solution of the equation systems governing the behavior of the rigid block assemblage. A simple incremental solution procedure is implemented to take into account the material softening behavior and the effects of large displacements on equilibrium conditions. The interface models are validated against tension and shear tests on bi‐block prisms from the literature. Applications to numerical and experimental out‐of‐plane loaded masonry walls as well as to circular arches with mortar joints are presented to evaluate the effects of tensile strength and the accuracy of the developed model against responses involving P‐Δ effects. Comparisons with experimental tests on shear walls also involving cracking of the units in the failure mechanisms are finally reported to discuss the potentialities and limitations of the proposed modeling approach. [ABSTRACT FROM AUTHOR]

The disturbance of the coal caving mechanism is the main method to solve the problem of coal falling into an arch during the top coal caving process, and the clearance in the caving mechanism is an important factor affecting its disturbance. To study the influence of clearance on the hydraulic supports, the dynamic analysis of hydraulic supports with two-level and three-level caving mechanisms is conducted considering the clearance. Based on Lagrange's equations of first kind, the mathematical model is constructed, and the equivalent spring stiffness of the oil cylinder is solved. The dynamic response of hydraulic support is studied by solving the mathematical model, and the relative position changes of the journal and bearing are compared. The research results prove that clearance has a better disturbance effect on the three-level caving mechanism. At the same time, the influence of clearance size and motion process on the motion error of the three-level caving mechanism is analyzed. Using the Kriging surrogate model and polynomial interpolation, the motion prediction model for the secondary tail beam with different clearance sizes is proposed, and the predicted values of the test samples are compared with the numerical solution values to prove the feasibility. [ABSTRACT FROM AUTHOR]

In the context of the San Gavain hydroelectric power station diversion tunnel project in Peru, this paper studies the surrounding rock instability mechanism using a combination of numerical simulation methods and model test and presents the enclosing rock instability criterion based on the catastrophe model. The study demonstrates that the distribution of stress and displacement during tunnel excavation is more affected by the presence of laminated joints; the thinner the layer thickness, the more prominent the influence of laminations, and the higher the deformation of the surrounding rock. With the increase in layer thickness, the resultant displacement shows the law of gradual decrease; when the layer thickness is greater than 16 cm, the rate of decrease gradually slows down, and the maximum displacement is 0.201 mm. The failure mode of the layered perimeter rock tunnel with a 45° inclination angle primarily shows up as tensile deformation at the left arch shoulder and shear slip deformation at the right arch foot under the combined action of blasting disturbance load and excavation. Based on the instability analysis of the fold catastrophe model and cups catastrophe model, the influence of bending deformation between layers of surrounding rock is generally greater than shear slip deformation. The instability criterion Δ＜0 exists in all working conditions, bending instability damage may occur in all cases. When the layer thickness is greater than 24 cm, the shear slip instability criterion is greater than zero for 0–2 ms, and the system is always in a stable state, and when the layer thickness is less than 24 cm, the system may be destabilized at 1.5 ms. [ABSTRACT FROM AUTHOR]

The western mining regions of China, known for shallow-buried and high-intensity mining activities, face significant ecological threats due to damage to loose strata and the surface. The evolution of fissures within the loose layer is a critical issue for surface ecological environment protection in coal mining areas. The study employed field measurements, mechanical experiments, numerical simulations, and theoretical analysis, using the 'triaxial consolidation without drainage' experiment to assess the physical and mechanical properties of various strata in the loose layer. Additionally, the PFC2D numerical simulation software was employed to construct a numerical model that elucidates the damage mechanisms and reveals the evolution of loose layer fissures and the development of ground cracks. The research findings indicate that during shallow-buried high-intensity mining loose layer fissures undergo a dynamic evolution process characterized by "vertical extension-continuous penetration-lateral expansion". As the working face advances, these fissures eventually propagate to the surface, forming ground cracks. The strong force chains within the overlying rock (or soil) layers develop in the form of an "inverted catenary arch". As the arch foot and the middle of the arch overlap, fissures propagate along these strong force chains to the surface, resulting in ground cracks. The study elucidates the surface damage patterns in shallow-buried, high-intensity mining, offering theoretical insights for harmonizing coal mining safety with ecological conservation in fragile regions. [ABSTRACT FROM AUTHOR]

This study aims to investigate the responses of shield tunnel structures subjected to disturbances caused by bilateral pit excavation, and it systematically reveals for the first time the impact mechanism of bilateral pit excavation on the distribution of perimeter pressure and deformation patterns of shield tunnels. Using a bilateral pit excavation project in Nanjing as a case study, this research establishes methods for calculating longitudinal displacement and circumferential pressure of tunnels under bilateral pit excavation conditions, employing the image source method for analysis. A refined three-ring segment model is developed, and the load structure method is used to analyze the impact of deep foundation excavation on the tunnel located between the two excavation sites. The results indicate that, compared to unilateral excavation, bilateral excavation significantly increases the perimeter pressure at the top and bottom of the tunnel, with a smaller increase in pressure at the arch waist. The deformation pattern is characterized by contraction at the top and bottom and expansion at the waist, forming a transverse elliptical deformation. The maximum vertical convergence values of the middle segment ring are 25.00 mm at the top and 25.88 mm at the bottom, with a vertical absolute convergence value of 44.5 mm and a convergence ratio (ΔDt/Dt) of 0.72%. As the foundation coefficient increases, the perimeter pressure at the top and bottom of the tunnel also increases. When the tunnel is closer to the foundation pits (Sp decreases), the perimeter pressure at the bottom of the tunnel increases. Conversely, as the distance between the two foundation pits (S) increases, the impact of excavation on the tunnel shifts from the upper part to the lower part, resulting in decreased upper perimeter pressure and increased lower perimeter pressure. The research findings provide important references for similar engineering projects. [ABSTRACT FROM AUTHOR]

Pseudo human settlements in the information age is an important part of human settlements geography, which has a comprehensive and profound impact on urban production, life and ecology in China and even the world, but the existing research on pseudo human settlements is still unclear, and cannot meet the requirements of China's "digital-realistic fusion", "network power" and the construction of a beautiful China. Therefore, this paper starts from the perspective of pseudo, based on the theory of the coupling system of human settlements, and applies the entropy weight method, coupling coordination model, geodetector and other methods and spatial technologies to deeply analyze the spatial and temporal evolution of the pseudo human settlements and the driving mechanism of the 14 cities in Liaoning Province from 2011 to 2020. The results show that: 1) Liaoning Province's pseudo human settlements in the time evolution of the overall quality of the main theme of the rise, with the "Internet festival" node effect and significant stage. 2) The spatial distribution is characterized by the geographical layout of "1"-type high-quality development centers and concentric-circle spatial distribution; and the trend surface shows a low uniformity pattern of "high in the south-central part and low in the surrounding area". 3) The degree of system coupling and the degree of coupling coordination both show a fluctuating upward trend, with the spatial heterogeneity characteristic of "high in the central part and low in the surrounding area". 4) Tool system has become the emerging driving force, communication and social chat has become the basic driving force, and life service is the invisible driving force; communication class and community class are the important leading driving factors. The study aims to enrich the research system of human settlements, promote the development of the discipline of human settlements geography, provide a new basis for the construction of human settlements in the new era, and respond to the demand for decision-making in the strategy of network power. [ABSTRACT FROM AUTHOR]

In this research, we are concerned with intraday volatilities computed by functional ARCH(1) (fARCH(1), for short) model for high-frequency financial time series. A conditional-Copula multiple change point detection (CPD) for intraday volatilities is proposed using fARCH(1), bivariate Gaussian Copula and t-Copula conditional distributions. We employ current available multivariate CPD models which include energy test based control chart (ETCC) and nonparametric multivariate change point model (NPMVCP) to implement the proposed CPD method for the intraday volatilities. A simulation study is conducted to demonstrate that the functional ARCH based conditional-Copula CPD for the intraday volatilities can be a useful econometrics method to detect abnormal intraday volatilities in the financial market. We analyze intraday volatilities of the Korea composite stock price index (KOSPI) and the Hyundai-Motor (HDM) company stock data with one minute high-frequency to illustrate our proposed CPD method. [ABSTRACT FROM AUTHOR]

The long-line abalone culture system in the bottom waters outside the bay is a new type of aquaculture facility that utilizes the underwater attenuation effect of waves to achieve better wind and wave resistance. Currently, most of the research on long-line aquaculture systems is aimed at the sea surface, and the research on the seabed is still pending. Therefore, to ensure the abalone culture system’ s survival rate and structural safety, it is of great significance to study the dynamic characteristics of the long-line abalone culture system in the bottom waters. Based on the similarity criterion, a model test was carried out in the wave-current flume laboratory; a numerical simulation method of the dynamic response of the long-line abalone culture system in the bottom waters was established based on the centralized mass model, and the accuracy of the numerical simulation method was verified. In view of the actual sea conditions off Luoyuan Bay, Fujian Province, the dynamic characteristics of the long-line abalone culture system in the bottom waters were numerically simulated under the action of different waves and currents to analyze the effects of the wave heights, current velocities and flow directions on the stresses on the abalone culture system and the structural safety of the system. The effects of wave height, current speed, and flow direction on the force and trajectory of the system were analyzed. The results show that the numerical model is consistent with the model test results: the maximum relative error of the maximum cable tension measured against the waves is 8. 33%, the minimum relative error is 4. 84%, and the average relative error of the peak horizontal and vertical motions of the float A is 5. 23% and 8. 92% respectively, which proves that the numerical simulation method used in this paper is accurate and reliable; there is a significant difference in the distribution of the force of the long-line and the anchor rope, and the force curve of the long-line shows an arch of the force. The force distribution of the long-line and the anchor rope has obvious differences; the force curve of the long-line shows an arch shape and a sawtooth shape, and the maximum force section is not on the anchor rope but located in the middle region of the long-line; the wave height has a linear relationship with the maximum force of the system and the motion amplitude of the abalone cage, i. e., the higher the wave height is, the larger the transverse and vertical motion amplitude of the system is, and the larger the maximum tension in the middle part of the long-line, the supporting rope and the anchor rope is, and the peak tension curve of the supporting rope shows a sawtooth shape; the maximum tension of the anchor rope in the headward side appears nonlinearly when the velocity of the current is increasing, the maximum tension of the anchor rope in the headward side appears nonlinearly. When the flow velocity increases, the maximum tension of the anchor rope on the headwater side shows a nonlinear steep increase. The maximum tension of the long-line on the headwater side increases slowly, and the maximum tension of the anchor rope and the long-line on the backwater side decreases significantly. In contrast, the maximum tension of the branch ropes does not increase significantly with the flow velocity, and the maximum tension of each branch rope is the same; when the flow direction increases, the maximum tension of the system’s anterior part of the longline and the anchor rope decreases. The posterior part of the long-line and the anchor rope increases, and the branch ropes’ tensions remain relatively stable. The results of this study can provide a reference for the structural design of similar long-line abalone culture systems in the bottom waters. [ABSTRACT FROM AUTHOR]

The in-plane stability of internally hinged, end-fixed shallow arches is in the spotlight. The non-linear model accounts for the coupled effect of the bending moment and axial force on the membrane strain. The model itself can handle homogeneous or non-homogeneous material distributions along the thickness of the uniform arch. Analytical findings reveal how the typical geometrical data, like arch length, radius of gyration, and arch angle, affect the lowest buckling loads. The typical non-linear behaviour of arches is also assessed including the equilibrium path and the internal force system. [ABSTRACT FROM AUTHOR]

This paper presents a laboratory testing rig designed to investigate the failure mechanisms and load transfer of rock masses under rock anchor loading. The study revealed that joint patterns significantly affect the strength and capacity of the rock mass, with existing design approaches based on apex angles of 90 ∘ or 60 ∘ found to be potentially overly conservative. Joint orientation and spacing should be included in the anchor design to obtain a more precise design criterion. In all the studied patterns, increasing the horizontal and vertical stress increased the block models' capacity, and load arching did not occur in the model with an unfavourable joint orientation. This study also revealed that the failure surface followed the joints in all tests and that the block model capacity was significantly higher than estimated with the design principle based on the weight of the overlying rock. The findings of this work have important implications for designing rock anchoring systems in mining and civil engineering demonstrate that joint orientation and block size significantly affect the rock mass capacity. This study confirms the need to consider the influence of in situ stresses on rock mass capacity when designing of rock anchors. Overall, this work guides the development of more precise design criteria for rock anchors, contributing to more efficient and effective rock engineering practices. Highlights: The models exhibited increase in horizontal stress upon application of a vertical anchor load to the blocks, indicative of load arching effects. The maximum vertical displacement in the blocks was in the normal direction to one of the joint sets under the influence of a vertical anchor load. The capacity of the block models was enhanced with an increase in both horizontal and vertical in situ stress. Crater-like failures were observed, with separation surfaces aligning with the joint set surfaces. Apex angles of the block patterns ranged from 90 to 140 ∘ ; symmetrical failures were observed in models with symmetrical jointing around the anchor. [ABSTRACT FROM AUTHOR]

Much has been learned over the last half century regarding the molecular and genetic changes that take place during cardiac development. As yet, however, these advances have not been translated into knowledge regarding the marked changes that take place in the anatomical arrangements of the different cardiac components. As such, therefore, many aspects of cardiac development are still described on the basis of speculation rather than evidence. In this review, we show how controversial aspects of development can readily be arbitrated by the interested spectator by taking advantage of the material now gathered together in the Human Developmental Biology Resource; HDBR. We use the material to demonstrate the changes taking place during the formation of the ventricular loop, the expansion of the atrioventricular canal, the incorporation of the systemic venous sinus, the formation of the pulmonary vein, the process of atrial septation, the remodelling of the pharyngeal arches, the major changes occurring during formation of the outflow tract, the closure of the embryonic interventricular communication, and the formation of the ventricular walls. We suggest that access to the resource makes it possible for the interested observer to arbitrate, for themselves, the ongoing controversies that continue to plague the understanding of cardiac development. [ABSTRACT FROM AUTHOR]

In this paper, a novel arch structure—circular box arch with sinusoidal corrugated webs (CBASCW)—is presented. Through the methods of theoretical derivation and finite element simulation, we studied its in-plane elastic buckling and in-plane elastoplastic stability. Through theoretical derivation, a shear stiffness formula of the arch section is determined, and the elastic buckling load when the arch is in pure compression state is proposed considering the shear deformation. We also introduced a simplified model, which can simulate the deformation and internal forces conveniently. The failure mode and global elastoplastic instability mechanism are investigated under uniformly distributed full-span radial load, uniformly distributed full-span vertical load, and uniformly distributed half-span vertical load. Furthermore, by introducing a regular slenderness ratio and stability coefficient, the stability curve of the arch under the state of pure compression is plotted. Subsequently, based on the stability curve and the numerical simulation results of a simplified model, a design formula for the stability bearing capacity is proposed for situations where global elastoplastic instability occurs. [ABSTRACT FROM AUTHOR]

The aim of this research is to investigate the impact of a viscoelastic foundation on the vibration of a curved beam structure with clamped and simply-supported boundary conditions. The structure considered is a micro-scale laminate composite beam made up of two piezoelectric face layers and a carbon nanotube-reinforced composite core. The study employs non-classical elasticity theory and nonlocal strain gradient theory to account for both nano-scale and microscale effects. The equations of motion are derived using the energy terms of the beam and a variational principle, with boundary conditions assumed to be clamped at one end and simply supported at the other end. A semi-analytical method of general differential quadrature method is used to solve the equations due to their nonlinear terms. To capture the effects of various parameters on the in-plane vibration of sandwich arches, an artificial neural network is designed and implemented. The study analyzes the impact of nonlocal and gradient parameters, geometrical aspect ratios, and substrate constants of the structure on the natural frequency and amplitude of vibration of the laminate beam. Results show that increasing nonlocal and gradient parameters have different effects on the amplitude and frequency of vibration of the beam. [ABSTRACT FROM AUTHOR]

• The internal force analytical solution of lining structure under P-ware action was obtained by using the analytical method. • The influence of the hardness of surrounding rock and peak acceleration on the analytical solution were analyzed. • Through the engineering, the reasons for the large error between numerical solution and analytical solution was analyzed. • The most unfavorable position of lining structure under P-wave seismic load was proposed. In an earthquake, the strong interaction between the surrounding rock and the lining structure causes the lining structure susceptible to extrusion or shear damage, and predicting the internal force distribution trend of the lining structure by the analytical method was advantageous for the preliminary design of the tunnel structure. In this work, the quasi-static method was used to approximate the displacement and deformation caused by the P-wave seismic load as far-field compressive stress. The analytical solution of the internal force for the lining structure was obtained by the analytical method, and the reliability of the analytical method was further verified. The dynamic response law of the lining structure was analyzed using numerical solutions in conjunction with engineering examples. The results show that the analytical method can be used to predict the trend of internal force distribution in the lining structure under seismic action, which has important theoretical guiding significance for the preliminary design of the tunnel structure. With the decrease in the hardness of the loess surrounding, the relative deviation of the theoretical, numerical, and literature results gradually decreases. With the increase of ground motion intensity, the interaction between the loess surrounding and the lining structure becomes more intense, and the internal force of the lining structure gradually increases. The numerical results were greater than the analytical results due to the consideration of the influence of initial stress. Under the action of the P-wave earthquake, the extreme values of the internal force with the lining structure mainly occurred at the location of the vault, arch waist, and inverted, and the most unfavorable positions of circular loess tunnel lining structures under P-wave seismic load was proposed. [ABSTRACT FROM AUTHOR]

• A dynamic theory of the HMS curved rod under 3D large deformation is presented. • The "tension-bending" and "shear-torsion" coupling effects of curved rod emerge in our model. • The finite element formulation and exact linearization of the dynamical problem are obtained. • An implementation based on Newmark algorithm and some numerical examples are presented. • Several experiments about a quarter arc HMS robotic arm are presented. Magnetorheological elastomers are active materials which can be actuated by the applied magnetic field. Hard magnetic soft (HMS) materials, a type of magnetorheological elastomers, show great potential in the fields of biomedical engineering and soft robotics, due to their short response time, remote operation, and shape programmability. To exploit its potential, a series of theoretical frameworks of HMS rods have been developed, but they are mainly limited to the static rod models or classical curved rod models that fail to consider the effect of the "initial curvature" on the distribution of the stress. In this work, we develop a curved rod theory to predict the 3D dynamic motion of the rod-like HMS robotics under large deformation. Based on the geometrically exact rod theory, we include the heterogeneous initial length of the longitudinal fiber caused by "initial curvature" into our model and obtain the reduced balance equations of the HMS robotics. As a result, the "tension-bending" and "shear-torsion" coupling effects of curved rods emerge in the present model. A numerical implementation of our model based on the classical Newmark algorithm is presented. To validate our model, three numerical examples, including the dynamic snap-through behavior of a bistable arch, are performed and compared with the simulation or experiment results reported in literatures, which show a good agreement. Finally, we experimentally study the 2D and 3D static and dynamic motion of a quarter arc HMS robotic arm under an applied magnetic field of 10 mT, and our model gives a satisfactory prediction, especially for static deformation. [ABSTRACT FROM AUTHOR]

The limit support pressure significantly influences the stability of the shield tunnel face and deformation control during tunneling. Current research predominantly focuses on soils under dried or saturated conditions. However, unsaturated soils, which are more commonly encountered in engineering practice and widely distributed, have not been as extensively studied. Based on limit equilibrium theory, a modified analytical wedge-prism model is proposed in this paper to predict the limit support pressure acting on the shallow shield tunnel face in unsaturated sandy soil where the soil arching effect is considered. Taking advantage of finite-element software ABAQUS (version 2021), a series of numerical trapdoor tests are conducted first to study the failure behavior of unsaturated sandy soil. Then, by combining the rotation trajectory of major principal stress with the shear strength theory of unsaturated soil, the loosening earth pressure solution above the shallow trapdoor can be derived analytically. The limit support pressure can be finally obtained through a force equilibrium analysis of the wedge body. The accuracy of the proposed model is validated by comparing the calculated results with current model tests and numerical simulations. Parameter analysis results reveal that both the loosening earth pressure and limit support pressure initially decrease and then increase with the rising degree of soil saturation. A critical saturation point is identified where the loosening earth pressure and the limit support pressure reach their minimum values, attributed to the full development of the soil arching effect. [ABSTRACT FROM AUTHOR]

The straight part of the corrugated steel plate (CSP) pipe-arch structure in soil may cause local buckling instability due to insufficient load-bearing capacity. Recently, composite CSP pipe-arch has been widely utilized to enhance structural stability, and their stability needs to be thoroughly investigated. This paper studies the local buckling stability problem of the straight part of composite CSP pipe-arch in soil by simplifying the soil support and introducing the inter-layer bonding effect. Based on elastic stability theory, a theoretical mechanical model of composite CSP pipe-arch was proposed. The Rayleigh–Ritz method and the semi-combined composite structure stiffness approximation were used to derive the critical buckling conditions for the straight part of the composite CSP pipe-arch. Through numerical calculation and influencing factors analysis, it is concluded that the critical buckling load of the straight part of the composite CSP pipe-arch structure is affected by the elastic modulus, thickness, Poisson's ratio, rotational restraint stiffness and side length of the straight part of the material. In particular, it is found that as the inter-layer bonding coefficient increases, the critical buckling load is improved, while the critical buckling wave number is mainly influenced by the width of the straight part, elastic modulus, and inter-layer bonding coefficient. Additionally, we discussed the coupling effect of several key parameters on the stability of the structure. The results of this study offer theoretical foundations and guidance for the application of composite CSP pipe-arch in soil engineering, such as culverts, tunnels, and pipeline transportation. [ABSTRACT FROM AUTHOR]

The construction duration of long-span arch bridges is excessively prolonged due to insufficient closing precision and the non-convergence of traditional cable adjustment calculation methods. This study investigates cable force management in long-span concrete-filled steel tubular (CFST) arch bridges during cable-stayed buckle construction, aiming to improve construction safety and precision in arch rib alignment. Using the Pingnan Third Bridge and Tian'e Longtan Bridge as practical examples, the research develops a multi-objective optimization method for cable forces that integrates influence matrices, constrained minimization, and a forward iterative approach. This method offers a robust strategy for tensioning and cable-stayed buckling, enabling real-time monitoring, calculation, and adjustment during the construction of large-span CFST arch bridges. The results reveal that the iterative approach notably enhances calculation efficiency compared to conventional methods. For instance, field measurements at the Pingnan Third Bridge show a minimal arch closure error of only 3 mm. Additionally, the study addresses concerns about excessive stress in exposed steel tubes during concrete casting. By optimizing the sequence of main arch closure and concrete casting, stress in the exposed steel tube is reduced from 373 MPa to 316 MPa, thus meeting specification requirements. In summary, the multi-objective cable force optimization method demonstrates superior efficiency in determining cable tension and controlling rib alignment during cable-stayed buckle construction of long-span CFST arch bridges. [ABSTRACT FROM AUTHOR]

When soft rock tunnels pass through fractured fault zones, they are particularly susceptible to extrusion and large-scale deformations, especially during seismic events. To address these challenges, this study introduces an innovative yield-support steel arch design featuring a circumferential letting pressure node at its core. This design delivers incremental support resistance within the deformation zone and a susceptibility curve is applied to evaluate the damage probability of the steel arch with a letting pressure node under seismic loading conditions. Measurements of the surrounding rock pressure and structural forces on the steel arch with the letting pressure node were conducted at the Baoshan Jewel Mountain Tunnel in China. The field experiment results revealed a 23% reduction in the surrounding rock pressure and an 11% decrease in the internal forces of the support structure. These findings demonstrate the successful application of the letting pressure node-supported steel arch in mitigating large deformations in soft rock environments. Additionally, using finite element software ANSYS 2022, a seismic time-history analysis was conducted, employing the relative deformation rate of the letting pressure node steel arch as the damage index and the peak ground acceleration (PGA) as the strength parameter to generate the incremental dynamic analysis (IDA) curve. According to the susceptibility curve derived from the incremental dynamic analysis, at the design ground motion level of 8 degrees, the letting pressure node steel arch has a 94% probability of exceeding its normal service life limit and experiencing damage. The findings of this study offer a novel approach to addressing large deformations in soft rock tunnels. The proposed susceptibility curves for steel arches with letting pressure nodes provide a robust foundation for predicting the damage probability of yielding support structures under seismic conditions. [ABSTRACT FROM AUTHOR]

Reasonable support force is crucial for the stability of the excavation face in sandy pebble tunnels. By utilizing the existing failure mode of the logarithmic spiral curve, this study combined the collapse arch model with the limit analysis method to establish a failure model for the excavation face in sandy pebble tunnels. A calculation method for the ultimate supporting force applicable to the excavation face of sandy pebble tunnels was also proposed. Then, the theoretical analysis presented in this paper was compared with numerical simulation and existing theories to determine the failure areas under different internal friction angles and cohesion values. Finally, the excavation face stability of a shield tunnel in Beijing was analyzed using theoretical analysis and numerical simulation methods. The results showed that the analytical solution proposed in this paper was in good agreement with the limit supporting force derived from existing research, with convenient and accurate calculations. The limit supporting force decreased nonlinearly with the increase of the internal friction angle, and was more sensitive to changes in the friction angle when the angle was small. The limit supporting force decreased approximately linearly with the increase in cohesion. When the burial depth was small, it had a more significant impact on the limit supporting force. When the C / D ratio exceeded 1. 0, the increase of the burial depth of the tunnel had no obvious effect on the limit supporting force, and the friction angle had a very significant effect on the failure area. With the increase of internal friction angle, the failure area decreased significantly. Cohesion had little impact on the failure area, i. e., the size of the energy dissipation surface remained nearly unchanged under different cohesion values. For the shield tunnel in Beijing, the calculation based on the limit analysis method optimized the collapse range and shape, making the failure mode more reasonable while increasing the failure range, achieving excellent engineering application results. [ABSTRACT FROM AUTHOR]

The shape design of arch dams requires consideration of multiple complex factors, such as the shape of the valley at the dam site, engineering geological conditions, regional seismic intensity, hub layout, and flood discharge methods. Therefore, the shape design of arch dams is a typical complex optimization problem. In this paper, a general parametric design method of arch dam shape is proposed, which can describe all kinds of arch dams such as parabola and hyperbola. By fixing the position of the arch end and adjusting the position, shape, and thickness of the arch crown beam to drive the shape change of the arch dam, automatic modeling and finite element stress deformation calculation of the arch dam are achieved. Taking the minimum volume of the arch dam as the optimization objective, intelligent optimization of the arch dam shape is carried out under constraints such as geometry, stress, and stability. Using this method to optimize the shape of a high arch dam, the optimization efficiency is high and the optimization effect is obvious. The stress of the optimized arch dam body and the equivalent stress of the foundation surface meet the requirements of the specifications, and the flexibility coefficient and stress level also meet the indicators recommended by experience. [ABSTRACT FROM AUTHOR]

Objective: The visual guiding system, as a tunnel traffic safety improvement method by using visual guiding facilities to actively guide driving safely, has been widely used in countries with many tunnels, in recent years. This paper aims to quantitatively study the comprehensive evaluation of traffic safety of the visual guiding system in tunnels, which has certain engineering application value and can provide support for the quantitative evaluation and optimal design of tunnel traffic safety. Methods: Based on the analysis of the relevant factors of urban tunnel traffic safety, a multi-factor comprehensive evaluation system with 5 upper-level indicators and 12 basic-level indicators was proposed. Considering the independent and incompatible indicators, a comprehensive evaluation method of traffic safety of the visual guiding system in urban tunnels was constructed by using the extension matter-element model. Taking the scene of 4 types of tunnel curves, such as no facilities, horizontal stripe, chevron alignment sign, and LED arch, as examples, the comprehensive evaluation of various schemes were carried out by using simulation tests. Results: The traffic safety comprehensive evaluation system of visual guiding system in urban tunnels can be analyzed from five aspects: perception reaction, guidance ability, driver factor, driving task, and facility appearance. The results demonstrated significant the comprehensive evaluation result of the target level of scene 1 was L4, scene 2 was L3, scene 3 was L2, and scene 4 was L1. That is, the final results of the comprehensive evaluation of the four scenes were poor, medium, good, and very good, respectively. Conclusions: In the scheme of visual guiding system for urban tunnel curves, the effectiveness of the three types of designs, from high to low, was the LED arch, chevron alignment sign, and horizontal stripe, and the safety of the scene without facilities was the lowest. Hence, setting the LED arch in the urban tunnel curve has a good effect in the aspects of guidance ability, sight distance, and sight zone, and is conducive to the driver's perception reaction and driving task. [ABSTRACT FROM AUTHOR]

One of the main barriers to the acceptance and adoption of fiber-reinforced polymers (FRPs) in structural engineering is the brittle failure mode and limited ductility caused by the elastic-brittle behavior of FRP materials. Introducing a compression-yield (CY) system is a promising way to improve the ductility of the structures. This study adopted perforated steel cylinders as CY systems. Six perforated steel cylinders with different parameters were tested, and the applicability of the existing constitutive model on the perforated steel cylinders was verified. A design approach for perforated steel members on the structures was proposed. Based on the proposed design approach, ultralightweight cement composite (ULCC)-filled carbon fiber-reinforced polymer (CFRP)-wrapped steel tube arches with perforated steel cylinders were designed and experimentally investigated. The ULCC-filled CFRP-wrapped steel tube arches with CY systems achieved high ductility while maintaining favorable bearing capacity. A model was then proposed to evaluate the damage degree of the structures based on the longitudinal strain in the CY system. The damage development of the structures can be detected based on the measurement of the CY system, which enables early warning to be provided before structural failure. [ABSTRACT FROM AUTHOR]

This paper presents an arch structure called the circular box arch with sinusoidal corrugated webs (CBASCW). This study investigates the out-of-plane elastic buckling behavior and elastoplastic stability capacity of the arch through a combined approach of theoretical derivation and finite element simulation. The section stiffness of the arch, including flexural stiffness, shear stiffness, and torsional stiffness, is achieved through theoretical derivation. Additionally, the elastic buckling load in both pure compression and pure bending states is derived. A simplified model is also introduced, which can conveniently simulate the internal force and deformation of the arch. The elastoplastic instability mechanism and failure mode are studied under various loading conditions, including uniform radial load, end bending moment, vertical load uniformly distributed in full-span, and vertical load uniformly distributed in half-span. Furthermore, the stability curves of the arch under conditions of pure compression and pure bending are graphed by incorporating stability coefficient and regularized slenderness ratio. According to the simulation results obtained from the simplified model and the analysis of stability curves, a design formula for stability capacity is proposed. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the validity of an orthotic deformation test on insole arches and the impact of researcher expertise on the test's reproducibility. Three researchers with different levels of experience evaluated orthotic deformation by applying a vertical force with their thumb on the dorsal surface of 48 polypropylene orthoses. An electromechanical test machine was used to evaluate the stiffness of the orthoses, and the results were compared with those of the orthotic deformation tests. Fleiss' kappa and weighted kappa and Mann–Whitney U tests were used to evaluate the interobserver reliability and the validity, respectively. There was no consensus among the three researchers (Kappa = 0.080; p-value = 0.334), although the two researchers with higher levels of experience exhibited moderate consensus (Kappa = 0.52; p-value < 0.001). Orthoses characterised by a positive test suffered from more pronounced deformation when a constant vertical force was applied by the electromechanical test machine (5.62 [4.64–7.38] vs. 4.56 [3.59–5.28] mm; p-value = 0.003). The orthotic deformation test is valid for interpreting the degree of deformation of polypropylene custom orthoses when it is compared with an axial force from a compression-device test. However, considering the high dispersion of the results, it suggests that clinical experience is required to properly interpret the tests. [ABSTRACT FROM AUTHOR]

In the process of tunnel construction, problems such as high-stress rockburst, large deformation of soft rock, water inrush and mud gushing, secondary cracking of linings, blasting interference, man-made damage, and mechanical damage are often encountered. These pose a great challenge to the installation of monitoring equipment and line protection. In order to solve these problems, the 2# inclined shaft of Muzhailing Tunnel in the Gansu Province of China, which exists under high stress, water bearing, and bias conditions, was taken as the research object in this paper. By assembling a string, drilling grouting and sealing, and introducing multiple modes of protection, new fiber grating sensor group installation and line protection methods were proposed. The automatic continuous monitoring of the deep deformation of surrounding rock and the automatic continuous monitoring of steel arch stress were realized. The field monitoring results showed that: (1) the fiber grating displacement sensor group could be used to verify the authenticity of the surface displacement results monitored by the total station; (2) the NPR anchor cable coupling support effectively limited the large deformation of soft rock and the expansion of surrounding rock in a loose circle, and the range of the loose circle was stable at about 1 m; and (3) the main influence range of blasting was at a depth of 0~5 m in surrounding rock, and about 25 m away from the working face. In addition, to secure weak links in the steel arch due to the hardening phenomenon, a locking tube was set at the arch foot. In the support design, the fatigue life of the steel was found to be useful as the selection index for the steel arch frame to ensure the stability of the surrounding rock and the long-term safety of the tunnel. The present research adopted a robust method and integrates a variety of sensor technologies to provide a multifaceted view of the stresses and deformations encountered during the tunneling process, and the effective application of the above results could have certain research and reference value for the design and monitoring of high stress, water-bearing, and surrounding rock supports in tunnels. [ABSTRACT FROM AUTHOR]

Drawing from the engineering context of a shallow-buried, biased-load, permeable ribbed double-arch tunnel, the strength reduction method was employed to determine the failure pattern of the surrounding rock at the tunnel's ultimate excavation state. According to the failure characteristics of surrounding rock and the basis of basic assumptions, a fractured sliding surface was hypothesized, and a structural load calculation model for the surrounding rock pressure in the permeable ribbed double-arch tunnel was derived. This model was compared and validated against the results obtained from the stratum structure model. An analysis of the sensitivity of the surrounding rock pressure was conducted. The findings indicated that the tunnel was subjected to asymmetric biased loads, with the vertical load on the side with large buried depth chamber being significantly greater than that on the side with small buried depth chamber. The horizontal load on the right sidewall of the side with large buried depth chamber was significantly greater than the horizontal load on the surface of the left and right lining segments above the central partition wall. The horizontal lateral pressure coefficient was influenced by the slope's biased angle and the internal friction angle of the surrounding rock's sliding surface, with the latter having a more substantial effect. The surrounding rock pressure was closely related to the horizontal lateral pressure coefficient and was influenced by the rock density, the slope's biased angle, and the internal friction angle of the sliding surface. The sensitivity of surrounding rock pressure was significantly impacted by the slope's biased angle and the internal friction angle. [ABSTRACT FROM AUTHOR]

The deformation and failure of the surrounding rock mass is a key issue during the construction of large‐scale underground powerhouse, and large discontinuities are likely to cause this problem in the presence of complex geological structures. This article takes the right bank underground powerhouse of the Baihetan Hydropower Station as a case study. In this case, deformation mutation of the surrounding rock mass occurred in the south section of the main powerhouse, with the maximum deformation reaching 178 mm, and the deformation and failure of different parts showed differences. A comprehensive study integrating field survey, site monitoring, laboratory test and numerical simulation was carried out. By field survey and monitoring, characteristics of deformation and failure are described, and the spatiotemporal difference in deformation is analysed. The stress evolution during excavation is studied based on numerical simulations, the mechanical response of rock is derived through laboratory tests, and the mechanism of spatiotemporal difference is revealed. The results indicate that the main reason for the spatiotemporal difference is the presence of slightly inclining interlayer shear zone C4. In the south section, the excavation‐induced stress concentration at the arch was enhanced due to C4, with the maximum principal stress exceeding 70 MPa, and the high compressive stress here triggered the deformation mutation of surrounding rock mass. After undergoing a stress path from concentration to unloading, the surrounding rock mass at the downstream sidewall was seriously damaged, and its deformation also mutated under approximately vertical stress. The mutation resulted in the uneven spatial distribution, large increment and time‐dependent feature of deformation. [ABSTRACT FROM AUTHOR]

Motivated by a curiosity to explore the behavior of innovative arch structures enabled by the use of fiber-reinforced polymer (FRP) composites, this paper proposes a theoretical model built upon an enhanced formulation of the deflection method, broadening its scope to large-curvature problems. Traditionally, the deflection method approximates curvature as the second-order derivative of deflection, a simplification valid only for small curvatures. This limitation poses a challenge when applying the deflection method to problems involving large curvatures, a characteristic inherent in FRP-enabled arches where significant curvatures arise either initially or due to deformation. The enhanced formulation at the core of the proposed model addresses this challenge by incorporating a circular deflection function. This function posits that each deformed segment of the structural member can be represented by a circular arc, with its curvature and length related to the internal axial force and bending moment at the midpoint section of the segment. This feature facilitates the exact representation of curvature, offering the proposed model a unified approach capable of addressing both small- and large-curvature problems. The paper details the formulation and verification of the theoretical model, with an emphasis on its application to representative cases of FRP-enabled arches. [ABSTRACT FROM AUTHOR]

The considerable increase in train velocity has intensified mutual aerodynamic effects between a train and a tunnel. How to effectively reduce the micro-pressure wave (MPW) amplitude at the high-speed railway tunnel exit is significantly important and has been recognized as an extremely challenging study, especially for the high-speed maglev tunnel when the train travels through it at 400 km/h or even more. To effectively mitigate the phenomenon of "sound explosion" caused by micro-pressure waves, this study provided a newly novel solution to mitigate the micro-pressure wave amplitude, which breaks up the traditional design idea and introduces a completely new arch lattice-shell structure inside the tunnel hood. In addition, the effect of the arch lattice-shell length on initial compression waves at high-speed maglev tunnel entrance and MPWs at exit were analyzed. The findings indicate that compared to the typical section-expanded tunnel hood, the new section-expanded lattice-shell hoods have a positive effect on the mitigation of micro-pressure waves emitted at the high-speed maglev tunnel exit. As the hood length increases, the alleviating effect is strengthened, resulting in a substantial decrease in the peak of the pressure gradient (Pg) and amplitudes of MPWs. When the section-expanded lattice-shell hoods are 50, 80, and 100 m in length, the pressure gradient peaks (Pg) are decreased by 6.2%, 34.9%, and 41.8%, respectively, while the corresponding amplitudes of MPWs are reduced by 9.4%, 46.8%, and 51.9%, respectively. Therefore, the new arch lattice-shell structure added inside the section-expanded tunnel hood can significantly mitigate the amplitudes of MPWs, which provides a newly novel solution for the tunnel hood design during the high-speed train passing through the tunnel at a higher speed. [ABSTRACT FROM AUTHOR]

Jalan Majalengka-Rajagaluh is a road located in several sub-districts that is a link to the city and one of the connecting roads to Cirebon City. This design planning began in Cigasong sub-district and continued to Rajagaluh sub-district with a length of 5.3 kilometers on the Majalengka-Rajagaluh road. The results of the geometric design are visualized in the form of drawings using AutoCAD 2D. The design speed (Vd) is set at 60 km/h with a horizontal curve radius of 358 m, a maximum slope of 4%, and an elevation (e max) of 8%. Based on this design criterion, a spiral curve with a circular arch length (Lc) of 74,996 m was obtained. Furthermore, the results of the calculation of the vertical alignment of the length (L) of one type of convex curve in the PPV are also calculated. [ABSTRACT FROM AUTHOR]

At present, the large-span porous steel corrugated plate arch culvert reinforced with composite beams of concretesteel corrugated plate (referred to as "concrete ring") has been preliminarily applied in actual projects. However, the force anddeformation characteristics in the construction process have not been studied in depth. This paper combines the in-situ test ofa9 m span steel corrugated plate arch culvert with 4 holes to monitor the mechanical behaviour of the concrete ring and the steelcorrugated plate, establish a refined finite element model, compare the force and deformation characteristics of the structure indifferent sections, and study the influence of the concrete ring on the structure. The results show that: 1) different arch spansand the presence or absence of the concrete ring have little effect on the deformation of arch culverts; 2) in the backfilling ofthe arch, the stress of the steel corrugated plate and rebar of the side span are greater than the corresponding position of themiddle span, and the maximum difference is 47.26 MPa and 49.75 MPa, respectively; 3) the concrete ring can significantlyreduce the stress of the steel corrugated plate, which is about 10% of its design strength. [ABSTRACT FROM AUTHOR]

In view of the instability issues of surrounding rock in super-large-section chambers, this study takes the super-large-section chambers of the underground agitation station at Jinfeng Gold Mine as the research object, establishes a rock quality index model for the mining area using the mine's geological drilling database, and based on this model, determines the optimal location for the agitation station construction to be at the 150 m level. Through laboratory tests, field investigations, and ground stress measurements, the parameters and stress distribution characteristics of the surrounding rock were determined. The stability of the chamber after excavation was analyzed using the Phase2 rock mechanics software for numerical simulation. Based on the analysis results and the engineering analogy method, a joint support scheme was proposed for the surrounding rock, which includes pipe-slit bolts, hanging mesh, wet shotcrete, resin bolts, long anchor cables, grouting behind walls, and anti-heave reverse arch concrete. The reinforcement effect was evaluated through numerical simulation and field application monitoring, and the results showed that the maximum deformation of the reinforced chamber was 31 mm, the maximum principal stress was 25 MPa, no damage occurred to the bolts (cables), and all safety factors of the concrete lining units were greater than 1.2. The support structure was in a reasonable and effective stress state, indicating that the chamber remained stable after reinforcement, with good support effects. The research findings have important reference value for similar engineering projects. [ABSTRACT FROM AUTHOR]

Introduction: Midfoot osteoarthritis (OA) is a painful and disabling condition. Arch contouring foot orthoses have been recommended for midfoot OA, yet there is no high‐quality evidence from randomised controlled trials to support their use. This clinical trial aims to evaluate the efficacy of arch contouring foot orthoses for midfoot OA. Methods: This will be a parallel‐group randomised controlled superiority trial. One‐hundred and forty community‐dwelling people with painful midfoot OA will be randomised to receive either arch contouring foot orthoses or flat sham inserts. Outcome measures will be obtained at baseline, 4, 8 and 12 weeks; the primary endpoint for assessing efficacy being 12 weeks. The primary outcome measure will be average midfoot pain whilst walking over the last 7 days on an 11‐point numerical rating scale. Secondary outcome measures include function (walking/standing subscale of the Manchester–Oxford Foot Questionnaire), participants' perception of overall treatment effect (self‐reported global rating of change on a 15‐point Likert scale), physical activity (Incidental and Planned Exercise Questionnaire), general health‐related quality of life (Short Form‐12 Version® 2.0), use of co‐interventions and adverse events. Discussion: This trial will evaluate the efficacy of arch contouring foot orthoses for relieving pain and improving function, physical activity and health‐related quality of life in people with midfoot OA. The findings will provide high‐quality evidence as to whether arch contouring foot orthoses are efficacious and will help to inform clinical guidelines about the use of foot orthoses for midfoot OA. Trial registration: Australian and New Zealand Clinical Trial Registry (ACTRN12623000953639). [ABSTRACT FROM AUTHOR]

Rock anchors, which can withstand substantial forces and are essential for securing the foundations of the built environment, can fail due to steel tensile failure, bond detachment, or rock mass fracturing through uplift. In this study, uplift failure of the rock mass surrounding rock anchors was simulated using both physical and numerical models. The physical models used a specially designed testing rig with predefined sizes and different joint layouts to simulate rock mass uplift failure. The numerical models were calibrated using the physical models and used to investigate scenarios involving increased complexity and greater depths. This paper presents the load distribution within rock masses with orthogonal joints when exposed to an anchor load. Extensive analysis of the numerical models revealed that symmetrical load arches were induced in rock masses that contained a joint set oriented parallel to the loading direction. However, joints that were obliquely oriented relative to the anchor axis induced asymmetrical load arching. The greatest displacement occurred in the direction parallel to the joint set with the smallest angle to the anchor loading axis. Large-scale models with zero or near-zero in situ horizontal stress revealed that the load capacity in a rock mass with continuous vertical joints was relatively low, especially when compared to rock masses with discontinuous vertical joints. It was observed that the uplift capacity of the rock mass around an anchor decreased if the load arches of adjacent anchors overlapped; consequently, a decrease in anchor spacing was found to correspond to a decrease in uplift capacity. Highlights: Symmetrical load arches are induced within a rock mass if the joint sets are oriented parallel to or close to parallel to the anchor axis. An oblique orientation of the joints relative to the anchor axis results in asymmetrical load arching in the rock mass when the anchor is loaded. Rock masses with continuous vertical joints have a low load capacity, especially compared to rock masses with discontinuous vertical joints. In a row of rock anchors, the rock mass uplift capacity of individual anchors is decreased if the anchor spacing is too low. [ABSTRACT FROM AUTHOR]

A new consolidation system for prestressed reinforced concrete (PSRC) beams of girder bridges is presented and evaluated. The system consists of two arch-shaped steel trusses placed alongside the lateral faces of the beam to be consolidated. The arches develop longitudinally along the entire span of the beam and in elevation using the available height of the PSRC cross-section. The consolidation system is characterised by its own external constraints, independent from those serving the pre-existing element. The efficiency of the system with respect to variable parameters is examined, focusing on the ratio between the load discharged by the consolidation system and the total applied load. Referring to a case study, consolidation of a PSRC beam adopting the proposed system is compared with the usually adopted external prestressing technique. The cross-sectional properties of the steel arch-shaped trusses are defined by means of a structural optimisation process using a genetic algorithm to identify the minimum steel consumption. Finally, a preliminary cost–benefit analysis is performed for the proposed solution and compared with other commonly adopted techniques. [ABSTRACT FROM AUTHOR]

The curved beam finite element approach based on the potential energy formulation is widely recognized as a versatile tool for lateral torsional buckling analysis of arches. However, there exist a variety of potentials, which were developed with distinct assumptions. The diversity of energy-based curved beam theories introduces confusions in practical applications. This paper aims to examine various potential energy formulations as to whether or not they obey the rigid body rule which is a prerequisite for valid second-order analysis. The induced moments at the ends of curved beam element that have been neglected from and/or the distributed moments that should be removed from available potentials are identified to help them become rigid body qualified. Based on the revised potential functional, a curved beam finite element formulation has been developed to effectively predict yet with less effort the out-of-plane critical load for circular and parabolic arches subject to various loading and constraint conditions. The results of numerical examples demonstrate that a potential energy formulation eligible for describing the out-of-plane behavior of curved beam is required to be rigid body qualified by fulfilling two aspects: (i) the neglected end moments that are imperative for satisfying the rigid body rule must be considered unless the virtual work done by them vanishes, and (ii) undesirable distributed moments that may be induced when undergoing the rigid body motion should be removed by considering all essential potential components. [ABSTRACT FROM AUTHOR]

The Partially Concrete Filled Steel Tube (PCFST) structure has gradually been applied to bridges as the main load carrying components in recent years, owing to the advantages of light weight and high stability. The failure mechanism and load carrying capacity of PCFST structure highly depends on the concrete filling ratio. For this purpose, the failure mechanism and parametric analysis of a single arched PCFST cable stayed bridge tower are investigated by using both refined solid element simulation and quasi-static experiment. The results shows that the PCFST arched tower experiences asymmetrical instability failure subjected to quarter span symmetrical loading, and the plastic hinges appears firstly at the tower arch closely above the tower columns, and then the bottom of the tower columns, forming a rotating mechanism leading to the instability failure. Filling concrete or not will result in two opposite deforming propagations of the plastic hinges, and when the concrete filling length exceeds the length of plastic hinge, the initial rigidity and ultimate load carrying capacity of the PCFST structure will sharply increase. Finally, according to the results of the extended parametric analysis based on the real size simulation, an improved initial stress reduction coefficient of PCFST structure is then suggested. [ABSTRACT FROM AUTHOR]

After excavation of tunnels in interbedded surrounding rock, accidents such as rock peeling and arch crown collapse are prone to happen. In response to this issue, we first established an analysis model for the excavation of the interbedded surrounding rock tunnel through theoretical analysis, proposed corresponding failure criteria, and analyzed the reasons for the easy failure of the interbedded tunnel support structure based on the concept of principal stress difference. We also created interfaces in FLAC3D (version 6.0) software to restore the actual interbedded interface, verifying the effectiveness of principal stress difference in analyzing the deformation characteristics of the tunnel. Then, the instability forms of the interbedded surrounding rock tunnel were divided into two types, and effective support methods for the corresponding instability forms were proposed. Finally, based on the analysis results of the study, support was provided for the collapsed tunnel on site. A grouting large pipe shed was put to innovative use to support the tunnel arch waist, stabilizing the surrounding rock that is prone to shear slip and fracture at the upper part of the arch waist. The results indicate that the surrounding rock control effect is good. This study has a good reference value for on-site rapid construction and support design, and is of great significance for the instability prevention and control of interbedded surrounding rock tunnels. [ABSTRACT FROM AUTHOR]

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Anti-slide piles are widely employed around the world to prevent landslides. They are typically designed to reduce the soil displacement rate well before the activation of the potential failure mechanism. Due to their excellent deformation coordination, portal anti-slide piles play an important role in the soil arching effect and provide a great anti-slide ability. This, along with their low project costs, has resulted in their wide application in landslide control projects. However, there is a lack of systematic research on the retaining mechanism and pressure transfer characteristics of portal anti-slide piles. This paper proposes a calculation method for the transmission process of earth pressure between pile rows based on the reduction and transmission of earth pressure between pile rows. A typical geological structural model for slope reinforcement is built and the soil between the portal anti-slide pile rows is divided into blocks along the sliding surface. Through the static equilibrium analysis of each block, the transfer effect of earth pressure between the rows of piles during the reinforcement process is determined. Following this, a calculation method for reducing soil pressure between the rows of piles is proposed based on quantifying the anti-slide effect to obtain the reduced soil sliding force in front of the rear pile, determine the form of action of soil between the rows of front and rear piles. Finally, the internal forces of the loaded and embedded sections of the portal anti-slide pile are calculated using the planar rigid frame model and the Winkler elastic foundation beam model, respectively. The results are verified using numerical simulation results and engineering applications. [ABSTRACT FROM AUTHOR]

The double-arch tunnel has been widely used in traffic engineering. As a key parameter of the partition wall, its thickness is closely related to the wall's bearing capacity. In this study, we use a double-arch tunnel passing through pulverized coal ash as an example and establish a numerical simulation model to study how the partition wall's thickness influences the tunnel's bearing capacity. The results show that the presence of the partition wall can significantly improve the stress state of the tunnel, meanwhile, excessive thickness of the middle partition wall can cause an increase of the arch crown stress. Compared to tunnels without a partition wall, when the thickness of the partition wall increases to 0.025 D, the arch load will increase by more than 30%. Furthermore, the results indicate that the bearing capacity is strongest when the thickness of the partition wall d is 0.0625 D. For tunnels without a partition wall, tensile stress concentration at the junction of the left and right holes will easily lead to cracking, and the right sidewall of the left hole will become the main compression part in the subsequent loading, resulting in complex tensile-compression-shear failure. For double-arch tunnels with a partition wall, the spandrel and the wall footing of the sidewall are the weak points of stress and are prone to damage, so these parts should be strengthened appropriately in design and construction. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)