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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]

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]

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]

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]

A three-lobed helical pipe was installed downstream of the bend of a vertical-horizontal pneumatic pipeline. The swirl characteristics under different helical pipe structures were investigated. Results show that: (a) the maximum velocity region rotates quasiperiodically, and the smaller the pitch, the faster the rotation; (b) the 3D morphological changes of the axial velocity distribution in downstream sections are similar: from an arch to a pit and finally to a uniform flat top. The tangential velocity appears as a Rankine vortex near the wall; (c) the swirl decays rapidly along the downstream. The initial swirl intensity, proportional to the helical pipe length, increases first and then decreases with decreasing pitch, whereas the structural parameters have minimal effect on the swirl decay rate; (d) the helical tube remarkably increases the system energy consumption, and the total pressure drop is inversely proportional to the pitch and proportional to the length. [ABSTRACT FROM AUTHOR]

The elastic solutions of isotropic complex noncircular deep or shallow tunnels are obtained by the complex variable theory in this paper. In the solution procedure, the mapping function in the form of power series is adopted and Cauchy integral formulas are widely applied to simplify the calculation. The unified solutions expressions for the mapping function with any number of series terms (namely the solving accuracy) are presented. When the terms number of the mapping function is determined, the solutions are accurate for the tunnels considering the influence of local rock gravity, as they are derived by analysis without any approximation and numerical method. Compared to previous analytical method that maps tunnels and surface boundary to rings, the surface boundary conditions of this method are not fully satisfied but the coefficients of the mapping function used are easier to solve, requiring fewer series, and the solution process is simpler and faster. Therefore, it is more suitable for deep and shallow rock tunnels that are not near the surface. Semi-circle arch, three-centered arch, horseshoe shape, asymmetric trapezoid and 'C' shape tunnels are analyzed as examples, and the validity of the results is verified by comparing the analytical solution obtained with the FEM numerical solution calculated in ANSYS software. Highlights: Elastic analytical algorithm for shallow rock tunnels with complex shapes is proposed. Solutions proposed are valid for the mapping function in power series form with any number of terms. The impact of tunnel asymmetry is considered in this study. High-accuracy solutions for tunnels with complex shapes are obtained by controlling the number of mapping function terms [ABSTRACT FROM AUTHOR]

This study aims to analyze the in-plane free vibrations of arches comprising the laterally symmetric functionally graded materials. Emphasis is placed on the circular arch whose material properties vary laterally symmetrically about the centroidal axis by a power-law function. The differential equations governing the mode shape of the arch were derived under the boundary conditions and were numerically solved to calculate the natural frequencies using the Runge–Kutta and Regula–Falsi methods. Calculation results of this study for natural frequencies compare well with those of the finite element method. The effects of various arch parameters on natural frequencies are highlighted and discussed in detail. [ABSTRACT FROM AUTHOR]

Background: Digital image correlation (DIC) has been widely used for motion tracking and estimation, however, the process is often sensitive to the initial guess, especially under large translations and rotations. Objective: To provide novel and effective solutions for the DIC in measuring large translations and rotations. Methods: A ring-projection-based two-scale approach is proposed. In the integer-pixel scale, a novel ring projection scheme, including amplitude and phase correlations of the rings, is developed to quickly get the integer-pixel initial estimation of the translations and rotation. In the sub-pixel scale, the gradient-based inverse compositional Gauss-Newton (IC-GN) algorithm, which is free from repeat computation of Hessian matrix, is adopted to efficiently get the optimal motion parameters. Results: The numerical example show that the absolute error is no more than 0.05 pixel for measured large translations and no more than 0.05 ∘ for measured large rotations. While test experiments on a rotated blade and a flexible arch demonstrate the effectiveness, accuracy and applicability of the proposed approach in measuring the rotating motion, flexible large deformation and vibrational modal parameters of structures. Conclusions: The ability and effectiveness of the proposed approach for large translations and rotations measurement have been verified. Since large deformations and rotations are frequently encountered in rotating and flexible structures, the proposed approach is believed to constitute a feasible and powerful tool for static and dynamic deformation measurement of these structures. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the stability of rocky slopes largely formed of sandstone and claystone clastics along Highway 80-2 in Mosul City, northern Iraq. Seven separate stations along the route were covered by the investigation, and each station included two to five study locations. Field studies were used to identify both man-made and natural slope failures caused by building a residential complex. The identification of these slopes' sliding surfaces was done using a user-friendly, contemporary method, with the potential for future advancements in measuring safety parameters. According to the analysis, the sliding potential is raised, especially during rainy seasons, by geotechnically weak rocks. Examples of these rocks include sandstone and claystone. The most important assumption underlying the suggested approach is a circle-shaped arch that is centered at the point where a vertical line from the slope's toe intersects the upper slope level. The sliding base is represented by the diagonal line inside the effective range of the slope, which relies on the angle of internal friction and is equal to the horizontal distance twice the vertical height of the slope. The angle of internal friction for most clastic slope materials was determined to be 27°. The slope inclination was used to determine the shape and sequence of sliding surfaces. As a result of the study's findings, it can be concluded that the suggested model accurately predicts the slides seen in the study area. [ABSTRACT FROM AUTHOR]

The h-type pile (hTP pile) is a complex anti-slip pile system, which connects the front pile and the back pile through beams. When it is used in engineering, there is a complex soil arch effect between the soil and the hTP piles, which makes the complex anti-slip mechanism. In this paper, the discrete element method is used to establish the hTP pile models, analyze the displacement and stress distribution law of the soil body and investigate the spatial distribution and variation patterns of soil arches, this can provide a basis for the design of hTP. The results indicate that the soil arch structure formed under the displacement between hTPs can be divided into four stages: initial stage, development stage, overlapping stage and stable stage. The development speed of the soil arch between the rear piles is slower than that of the soil arch between the former piles. As the depth of the soil increases, the arch line of the soil arch gets closer to the rear pile. The soil arch of the stress between hTPs can be divided into initial stage, development stage and stable stage. The time step corresponding to the stable stage of the stress in the horizontal direction is equal to the sum of the horizontal displacement generated by the overlapping stage and the stabilization stage. The stress of the soil slope gradually decreases and extends from the surface to the bottom layer of the slope. Soil arches appear on the rear side of both the front and rear piles at different anti-slip pile spacings, and they all tend to overlap. The increase in pile spacing does not have a significant effect on the ratio of soil arch height and soil arch span, and the evolution of soil arch is similar between hTP at different pile spacings. All above can provide reference for the application and design of hTPs. [ABSTRACT FROM AUTHOR]

To achieve sustainable desalination and water purification, solar interface evaporation technology is an effective means due to its high energy efficiency. Reasonable photothermal conversion materials and surface design are crucial for the interfacial solar evaporation process. How to design water transport routes and thermal insulating layers simultaneously is one of the major challenges to solar interface evaporation technology today. Herein, this work reports an arch-shaped wood evaporator (pine@carbon black (CB)-metal-organic framework-801 (MOF-801)-36%) for efficient, fast and continuous interfacial solar evaporation, which is composed of an arch-shaped wood substrate, MOF-801, and CB as a light absorption layer. The arch-shaped structure has a double-sided evaporation effect, which has a synergistic effect on augmenting solar evaporation efficiency. In addition, the in-situ growth of MOF-801 in pretreated wood microchannels renders the wood evaporator a significant function of reducing the equivalent enthalpy of evaporation due to the reduction of the hydrogen bonding density of water molecules as they pass through the wood channels. The best evaporation rate of the arch-shaped wood evaporator can reach 2.535 kg·m−2·h−1, and the efficiency reaches 93.7% under the irradiation of 1 sun illumination. Notably, it could be used for desalination and wastewater treatment to collect fresh water that meets drinking requirements set by the World Health Organization (WHO). This integrated evaporator provides an efficient way for commercial portable photothermal conversion and new ideas for advanced solar-driven water treatment technology. [ABSTRACT FROM AUTHOR]

Up to the beginning of the twenty-first century, most of quasi-brittle structures, in particular the ones composed by concrete or masonry frames and walls, were designed and built according to codes that totally ignored fracture mechanics theory. The structural load capacity predicted by strength-based theories, such as plastic analysis and limit analysis, do not exhibit size-effect. Within the framework of fracture mechanics theory, this paper deals with the analysis of the effect of non proportional loadings on the strength reduction with the structural scaling. In particular, this study investigates the size-effect of quasi-brittle materials subjected to self-weight. Although omnipresent, gravity-load is often considered negligible in most studies in the field of fracture mechanics. This assumption is obviously not valid for large structures and in particular for geometries in which the dead load is a major driving force leading to fracture and structural failure. In this study, an analytical formulation expressing the relation between the strength-reduction and the structural scaling and accounting for self-weight, was derived for both notched and unnotched bodies. More specifically, a closed form expression for size and self-weight effects was first derived for notched specimens from equivalent linear elastic fracture mechanics. Next, equivalent linear elastic fracture mechanics theory being not applicable to unnotched bodies, a cohesive model formulation was considered. Particularly, the cohesive size effect curve and the generalized cohesive size effect curves, originally obtained via cohesive crack analysis for weightless bodies with sharp and blunt/unnotched notches, respectively, were equipped of an additional term to account for the effect of gravity. All the resulting formulas were compared with the predictions of numerical simulation resulting from the adoption of the Lattice Discrete Particle Model. The results point out that the analytical formulas match very well the results of the numerical model for both notched and unnotched samples. Furthermore, the analytical formulas predict a vertical asymptote for increasing size, in the typical double-logarithm strength versus structural size representation. The asymptote corresponds to a characteristic size at which the structure fails under its own weight. For large structural sizes approaching this characteristic size, the newly developed formulas deviate significantly from previously proposed size-effect formulas. The practical relevance of this finding was demonstrated by analyzing size and self-weight effect for several quasi-brittle materials such as concrete, wood, limestone and carbon composites. Most importantly, the proposed formulas were applied to the failure of semi-circular masonry arches under spreading supports with different slenderness ratios. Results show that analytical formulas well predict numerical simulations and, above all, that for vaulted structures it is mandatory accounting for the effect of self-weight. [ABSTRACT FROM AUTHOR]

Variations in the arch of the aorta and aortic valves among fetal, cadaveric, and post-mortem specimens present a spectrum of anatomical configurations, posing challenges in establishing a standard norm. While some variations hold surgical significance, many bear little functional consequence but provide insights into embryological origins. The aortic arch exhibits diverse branching patterns, including common trunks and different orders, relevant for endovascular surgeries. Meanwhile, malformations in the aortic valve, affecting the aorta, may lead to ischemia and cerebral infarction, warranting understanding of coexisting arch and valve anomalies to predict complications like aortic dissection. Studies in the Indian population mirror global variations, underscoring the need to explore embryological, clinical, and surgical implications for safer vascular surgeries involving the aortic arch and valves. The study's objectives included examining branching patterns, diameters, and distances between arch branches and exploring aortic valve variations. Employing a cross-sectional design, the study was conducted across Anatomy, Forensic Medicine, and Obstetrics and Gynecology departments. A sample of 100, comprising cadavers, fetuses, and postmortem specimens, were gathered. Specimens ranged from 14 weeks of intrauterine life to 85 years, with intact thoracic cages as inclusion criteria. Methodology involved dissection, specimen fixation, and macroscopic examination for variations and morphological parameters. Results showed aortic diameter increase with age, with significant gender differences. A statistically significant association between arch variations and anomalous valves was observed, suggesting mutual predictability. Individuals with valve anomalies should undergo comprehensive cardiology evaluation to avert complications like aortic dissection during endovascular surgeries. While atheromatous plaques were prevalent in younger groups, their frequency rose with age, necessitating vigilant vascular monitoring. Careful handling during surgeries is paramount, given potential adverse outcomes resulting from variations. Overall, the study underscores the importance of comprehensive anatomical understanding in clinical contexts, guiding effective management strategies and ensuring patient safety in vascular surgeries. [ABSTRACT FROM AUTHOR]

Based on the existing research results on prefabricated shear wall vertical bolt connections, the force performance of horizontal bolt joints composed of multiple bolt connections were further examined in this paper. Through the quasistatic load test of two horizontal bolt joint specimens, the hysteresis curve, backbone curve, and stiffness degradation curve of the wall were obtained. The test results show that the specimens' load-bearing capacity can reach 240–280 kN, with a maximum displacement between 40 and 70 mm, indicating that the force performance and deformation ability of the horizontal joint are good at this size. The overall shape of the hysteretic curve of the specimens is similar to an arch, with a certain pinch effect, and the hysteretic loop is relatively full, indicating good energy dissipation ability. The failure of the specimens reveals that a single bolt connection exists under shear, compression and tension conditions. The force state of the bolt connections in the horizontal joints was divided into four situations: shear state, axial compression state, small eccentric compression state and large eccentric compression state. For each situation, a calculation formula for bolt connections in horizontal joints was proposed and the average relative error is 4.72%, providing a reference for the force calculation of this type of joint. [ABSTRACT FROM AUTHOR]

To study the impact of blasting construction of double-layer superimposed primary support arch cover method, relying on the station construction project of Dalian Metro Line 5, the disturbance of blasting on high-rise buildings, surrounding strata, adjacent pilot tunnels and the arch structure is analyzed based on numerical simulation and field monitoring results. At the same time, research is carried out on the blasting excavation footage of pilot tunnels. The results show that there will be a certain "elevation amplification effect" (EAE) on high-rise buildings during the blasting construction using the method. The peak particle velocity (PPV) of adjacent tunnels decreases gradually with the increase of the distance from the explosion centers. For the adjacent pilot tunnel, the main influence area is within the range of − 5 to 5 m from the pilot tunnel face. For adjacent buildings, the main influence stage is within the range of − 2 to 2 m from the pilot tunnel face. Blasting operations significantly intensify the plastic yield of surrounding rocks around the station. Blasting excavation footage can be used as the optimization parameter in the construction process, and the blasting excavation footage of pilot tunnel 4 can be adjusted from 1.0 to 1.5 m. The formation of the arch structure composed of double-layer superimposed primary support and secondary lining effectively reduces the impact of rock blasting on the whole station and high-rise buildings. [ABSTRACT FROM AUTHOR]

Clear aligners are employed daily for the treatment of several malocclusions. Previous clinical studies indicated low accuracy for the correction of tooth rotations. The aim of this study was to evaluate the predictability of tooth rotations with clear aligners. The sample comprised 390 teeth (190 mandibular; 200 maxillary), measured from the virtual models of 45 participants (21 men, 24 women; mean age: 29.2 ± 6.6 years old). For each patient, pre-treatment (T0) digital dental models (STL files), virtual plan (T1) and post-treatment digital dental models (T2) of both the mandibular and maxillary arches were imported onto Geomagic Control X, a 3D metrology software which allows angular measurements. Rotations were calculated by defining reproducible vectors for all teeth in each STL file and superimposing both T0 with T1 to determine the prescribed rotation, and T0 with T2 to determine the achieved rotation. Prescribed and achieved rotations were compared to assess movement's accuracy. The Wilcoxon signed-rank test and paired t-test were used to assess differences between the prescribed and achieved movements (P < 0.05). The overall predictability of rotational movement was 78.6% for the mandibular arch and 75.0% for the maxillary arch. Second molar accuracy was the lowest in both arches. Clear aligners were not able to achieve 100% of the planned movements. [ABSTRACT FROM AUTHOR]

The age, creatinine, and ejection fraction (ACEF) score has been accepted as a predictor of poor outcome in elective operations. This study aimed to investigate the predictive value of ACEF score in acute type A aortic dissection (AAAD) patients after total arch replacement. A total of 227 AAAD patients from July 2021 and June 2022 were enrolled and divided into Tertiles 1 (ACEF ≤ 0.73), Tertiles 2 (0.73 < ACEF ≤ 0.95), and Tertiles 3 (ACEF > 0.95). Using inverse probability processing weighting (IPTW) to balance the baseline characteristics and compare the outcomes. Cox logistic regression was used to further evaluate the survival prediction ability of ACEF score. The in-hospital mortality was 9.8%. After IPTW, in the baseline characteristics reached an equilibrium, a higher ACEF score before operation still associated with higher in-hospital mortality. After 1 year follow-up, 184 patients (90.6%) survival. Multivariable analysis revealed that ACEF score (adjusted hazard ratio 1.68; 95% confidence interval 1.34–4.91; p = 0.036) and binary ACEF score (adjusted HR 2.26; 95% CI 1.82–6.20; p < 0.001) was independently associated with 1-year survival. In addition, net reclassification improvement (NRI) and integrated differentiation improvement (IDI) verified that the ACEF score and binary ACEF score is an accurate predictive tool in clinical settings. In conclusions, ACEF score could be considered as a useful tool to risk stratification in patients with AAAD before operation in daily clinical work. [ABSTRACT FROM AUTHOR]

The Changjinghuang Railway Xinjiang Xizhi Bridge is a (90 + 180 + 90) m continuous beam arch bridge, and the arch rib steel pipe installation adopts "short bracket assembly and overall lifting method". In order to ensure the accuracy of closure, the stress and deformation of the arch rib and bracket must be strictly controlled. Midas Civil is used to establish the finite element model to simulate the overall lifting construction process of the arch rib. Based on the model, the stress and deformation of the arch rib and the supports are analyzed, and the determination method of the horizontal cable force under temperature variations is proposed. The results show that the stress and deformation of the arch rib and bracket meet the requirements. Considering the variation of temperature, the tension force of the horizontal cables is taken as 200 t. The construction plan proposed under the guidance of numerical calculation results has been proven by practical engineering to meet the requirement of closure accuracy, which can be used as a reference for similar projects. [ABSTRACT FROM AUTHOR]

Nanocomposites have gained fame due to their characteristics and are used in many industries such as automotive, aerospace, and biomedical. Also, curled structures (arches) are deeply applicable in fields of engineering. So, in this paper, the influence of nanoparticles' aggregation on the behavior of the dispersed elastic waves in the hybrid nanocomposite arches is evaluated for the first time. The arches are supposed to be made of hybrid multi-scale nanocomposite reinforced with single-walled carbon nanotubes and carbon fibers. The physical properties of arches are calculated in the framework of the rule of the mixture and the Eshelby–Mori–Tanaka homogenization model. The theoretical formulation of kinetic relations of the arches is presented based on the Euler–Bernoulli curved beam theory. Moreover, Hamilton's principle is applied to obtain the partial differential governing equations of arches. In the next step, an analytical solution method is implemented to solve the derived partial differential equations, and then, the frequency and velocity of the dispersed waves will be calculated. Next, the impacts of different effective parameters on the change of wave dispersion of hybrid nanocomposite arches are comprehensively studied. Finally, the obtained outcomes are reported in detail namely the correlations between phase velocity, wave frequency, weight fraction, etc. [ABSTRACT FROM AUTHOR]

Underground excavation is usually accompanied by complex soil-structure interaction problems in practical engineering. This paper develops a novel multi-scale approach for investigating the soil arching effect through trapdoor tests. This approach adopts the finite element method (FEM) and smoothed particle hydrodynamics (SPH) method to handle the particle-rigid body interaction in the trapdoor tests, incorporating a micromechanical 3D-H model to derive the nonlinear material response required by the SPH method. The variation of the earth pressure on the trapdoor in simulations exhibits good agreement with those of the experiments. Extensive parametric analyzes are performed to assess the effects of soil height and inter-particle friction angle on the evolution of load transfer and soil deformation. Three deformation patterns are observed under different buried conditions, including the trapezoid, the triangle, and the equal settlement pattern. Results indicate that the planes of equal settlement develop progressively with the trapdoor movement and then enter the range of experimentally observed values. Additionally, three failure mechanisms are identified that correspond to the three deformation patterns. Due to the advantages of the micromechanical model, mesoscale behavior is captured. The anisotropy of stress distribution in the plastic region is found during the arching process. [ABSTRACT FROM AUTHOR]

The process of buckling of the von Mises truss in the case of material instability, i.e., with allowance for material non-ellipticity, is considered. Force-displacement diagrams are constructed. Results that allow one to study buckling of thin-walled structures (arches or shells) made of materials for which the loss of ellipticity of equilibrium equations is possible are obtained. [ABSTRACT FROM AUTHOR]

In this paper, the nonlinear large-amplitude vibrations of shallow arch structures made of functionally graded materials (FGMs) under cooling shock have been investigated. It is considered that the FG shallow arch is made of low carbon steel AISI 1020 and stainless steel (SUS 304) , whose material properties change in the thickness direction. Using the kinematic assumptions that are modeled based on the first-order shear deformation theory (FSDT) and the von Kármán's geometrical nonlinearity; along with the aid of Hamilton's principle, the shallow arch motion equations are obtained. The material properties vary in the direction of arch's thickness due to the temperature changes and material distribution. Based on the Voigt rule of mixture and power law distribution, the dependence of material properties on temperature and material distribution is defined. Assuming uncoupled theory of thermoelasticity, first, the one-dimensional heat conduction equation is solved along the thickness of the arch in order to obtain the temperature distribution. Afterward, the equations of motion are solved. For the numerical solution of the heat conduction equation and the nonlinear equations of motion, the iterative hybrid method of generalized differential quadrature and the Newmark time integration scheme has been used in an iterative Newton–Raphson loop. After validating the present formulation, a parametric scrutiny is conducted regarding the influence of various parameters, namely, thermal load rapidity time, FG-index, dimensional parameters on the mid-plane non-dimensional lateral deflection of the arch as well as the changes in stress and material properties. [ABSTRACT FROM AUTHOR]

With the continuous development of underground engineering to the deep, complex geologic conditions such as high stress, extremely soft rock and fault fracture zone usually occurred in the construction process. The accurate calculation of confined concrete arch bearing capacity is the key to support design. At present, the theoretical value of the bearing capacity for the confined concrete arch is oppositely deduced according to the axial compression bearing capacity of basic component, and the bending moment effect of surrounding rock on arch is neglected. It does not consider the structural characteristics of inconsistent stiffness between the arch joints and segments. To obtain accurate calculation results, a theoretical calculation model of arch with arbitrary section numbers and unequal stiffness is established. By the full-scale laboratory and numerical tests, the deformation and failure characteristics of the confined concrete arch are analyzed. The results show that the vault position, bottom position and waist position are the key failure positions of the arch. The difference rates of theoretical calculation results compared with laboratory test results of ultimate bearing capacity are within 5%, which verifies the rationality and correctness of theoretical calculation model. On the basis of the above research, the support design method of confined concrete arch is proposed. The support parameters of on-site confined concrete arch are designed based on the engineering background of the typical deep mine with high stress—Liangjia coal mine located in China. The surrounding rock of the roadway is stably controlled. [ABSTRACT FROM AUTHOR]

In order to study the evolutionary law of roof migration on Gob-Side Entry Retaining, this paper takes the gob-side entry retaining in the comprehensive mining face of the Ningtiaota coal mine as the engineering background, and analyzes the evolutionary law of the overlying rock layer on the roof at different locations during the roadway stay and the stress distribution around the roadway through numerical simulation software, which shows that there is a concentration of stress inside the Flexible formwork concrete wall, and therefore the maximum settlement of the roof on the side of Flexible formwork concrete wall is 35.35 mm, due to the existence of "arch-shaped" decompression area from the working face. Therefore, the maximum settlement of the roof slab on the side of flexible formwork concrete wall was 35.35 mm. Due to the existence of "arch-shaped" decompression area on the roof and floor of roadway, the settlement of the roof slab on both sides of the roadway gradually increased when it was from − 20 to 10 m away from the working face, and the central position had the following pattern of firstly decreasing and then gradually increasing, and then exceeding the top of the roadway. After decreasing and then gradually increasing, after 10 m ahead of the working face, the two sides of the roadway roof subsidence law and the central part of the roadway to maintain the same; the use of cutting the top of the flexible mold concrete wall support technology as a means of controlling the top of the roof along the empty roadway subsidence, the analysis shows that the roof after roof cutting of the amount of subsidence have been reduced, the maximum difference in the rate of change of the displacement is 0.011%, and the maximum difference in the amount of subsidence of 4.98 mm; through the field monitoring data analysis of the pressure of mining The peak value of the influence curve of the working face is located at 19 m of the working face, 9 m of the lagging working face and 19 m of the roadway outside the working face are less affected by the additional mining stress field, comparing the fracture brokenness of the roadway roof before and after the roof cutting, the fracture area in the uncut section is much larger than that in the section of the roof cutting. [ABSTRACT FROM AUTHOR]

Increasing computational power has led to the expansion of civil engineering research into using machine learning concepts for developing improved design strategies. These strategies are particularly useful for the design of extra-terrestrial habitats under uncertain environmental conditions. This paper focuses on building an unsupervised machine learning model (convolutional autoencoder) capable of detecting patterns in arch shapes and differentiating between their stress and displacement contours. Foremost, detailed discussions of the model's architecture and input data are presented. The variation of arch shapes and contours between cluster centroids in the latent space is determined, proving the capability of optimisation by moving towards clusters with optimal contours. Finally, a regression model is built to investigate the relationship between the input geometric variables and the latent space representation. We prove that the autoencoder and regression models produce arch shapes with logical structural contours given a set of input geometric variables. The results presented in this paper provide essential tools for the development of an automated design strategy capable of finding optimal arch shapes for extra-terrestrial habitats. [ABSTRACT FROM AUTHOR]

This article presents a sophisticated approach to updating the finite element model of two historical arch masonry bridges located in the challenging terrain of Kalka Shimla mountain railway, using vibration testing results. To estimate the dynamic characteristics of the bridges, ambient vibration testing was carried out. Next, initial finite element models of the bridges were developed based on geometrical survey data. Sensitivity analysis was used to determine which parameters needed to be modified for the bridges. The response surface method and global optimization techniques were employed to identify the optimal values of structural parameters that would result in a satisfactory agreement between the numerical and measured natural frequencies of the heritage bridges. Ultimately, the methodology provided a surrogate mathematical model to represent the relationship between structural parameters and dynamic response, and could predict the damage status of the historical bridges. [ABSTRACT FROM AUTHOR]

The effect of a supports settlement in a symmetric masonry arch is studied by modeling the arch as a system of rigid plastic blocks with frictional sliding. It is shown that in a collapse state due to a horizontal settlement the thrust attains its minimum statically admissible value, so extending to the case of frictional sliding a well-known result of standard limit analysis, which considers collapse states only due to the opening of joints. The case of both vertical and horizontal settlements is also analyzed. It is demonstrated that the collapse thrust in case of horizontal settlement is a lower bound for the collapse thrust in case of generic settlement. Extensive numerical analyses illustrate the above results. [ABSTRACT FROM AUTHOR]

In response to the lack of clear and available specifications for controlling rock mass deformation in large underground caverns, a study was conducted to establish standards for controlling the deformation of the cavern crown arch region. The study utilized the rock mass ultimate strain as an indicator to quantify the degree of rock extrusion and assess cavern stability. Various empirical formulas for calculating the rock mass ultimate strain were compared in detail, and robust and comprehensive formulas were selected. A geometric calculation model for the deformation of the underground cavern crown arch was established considering uneven deformation. A theoretical analytical method was employed to derive a relationship between the displacement of feature points on the crown arch and the rock mass ultimate strain. Accordingly, the deformation control standard for the crown arch in underground caverns was established, along with a hierarchical management mechanism. The engineering case study indicates the following: (1) the theoretical analytical method provides an innovative way to establish deformation control standards for a large underground cavern crown arch. (2) The allowable deformation value of the crown arch is closely related to the dimensions of the cavern profile and the surrounding rock mass strength properties. (3) The proposed deformation control standard for the crown arch has significant engineering implications in controlling crown arch deformations and evaluating the surrounding rock stability in caverns. Highlights: A detailed comparison was conducted to select more robust and comprehensive empirical formulas for calculating the ultimate strain of a rock mass. Theoretical analytical methods were employed to derive and establish deformation control standards for a large underground cavern crown arch. A hierarchical management mechanism was developed for the proposed deformation control standard. The application of the proposed control standard in an engineering case demonstrates its potential engineering value. [ABSTRACT FROM AUTHOR]

When a tunnel passes through weak and fragmented surrounding rock, excavation disturbance can lead to significant deformation. To mitigate this, advanced support measures like the umbrella arch are necessary. This study investigates the effectiveness of the umbrella arch in controlling deformation of the surrounding rock, focusing on the super shallow-buried spillway section of the Shenzhen East Transit Expressway in China. Both numerical modeling and field monitoring were used to assess the support effect of the umbrella arch. The mechanism of the support was analyzed, revealing that the umbrella arch primarily prevents collapse of the surrounding rock by creating a small compression area. It is recommended that a starting segment with the same length as the tunnel diameter be reserved for the construction of long umbrella arches to maximize their supporting effect. The proposed numerical model was calibrated using field monitoring data, and the mechanical responses of an 80-m-long umbrella arch during construction were thoroughly analyzed. The research results presented in this paper can serve as a reference for the design of umbrella arches in similar projects in the future. [ABSTRACT FROM AUTHOR]

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Purpose: This study investigates the uncertain eigenvalue analysis of graded porous and sandwich arches, considering material stochasticity, using an efficient perturbation-based stochastic finite element approach founded on the three-nodded element. Internal pores in the graded porous arch follow three distinct types of distribution: type 1, type 2, and type 3. The mechanical properties of a graded porous arch change in the thickness direction. Method: The present stochastic finite element formulation is based on higher order shear deformation theory in conjunction with the probabilistic first-order perturbation technique (FOPT). Results: The present model is validated using limited results from the literature as well as independently developed Monte Carlo simulation (MCS) results. The impacts of various influencing parameters such as opening angle (θo), porosity distribution type, the thickness-to-length ratio (h/L), and porosity coefficient (eo) on the uncertain eigenvalue analysis of the graded porous and sandwich arches have been investigated in the parametric study. Conclusion: It is found that the SD/Mean of the frequency of the graded porous arch is more susceptible to distribution type 3. [ABSTRACT FROM AUTHOR]

Purpose: In the context of worldwide efforts to reduce plastic waste, the authors of this document patented a cement mortar floor slab interjoist prefab vault incorporating recycled plastic. This piece was designed to be used for the refurbishment of Spanish traditional timber jack arch floor slabs. Taking into account nowadays context, it is essential to assess the environmental benefits of this product. Methods: A cradle to gate LCA has been performed following ISO 14044 and ISO 15804 recommendations. Thus, the aim of this research is both to provide a measure of the environmental improvement that this material adds to the building process and to compare it with current most used construction elements used for the same function. It is stressed that this study is based mainly on primary data obtained from Spanish producers. Results: The results obtained show that the reference scenario, corresponding to the new patented vault, is the system with lower impacts in six out of the seven categories assessed. Furthermore, when adding the LCA normalisation step, the conducted analysis show that for the most influential impact categories, GWP100a and AD fossil fuels, the reference scenario bears the lowest scores. Conclusions: It can be concluded that the new patented vault has a better environmental performance than the assessed commercial vaults. Therefore, in this research, the benefits for the construction sector to incorporate recycled plastics are shown. Furthermore, these results can encourage the research on construction products that include recycled plastics in their composition. Bearing in mind that this study assesses the impacts corresponding to the production of a prototype of the newly vault, it is considered that there is room for further improvement through the optimisation of the production process. [ABSTRACT FROM AUTHOR]

The field monitoring data showed that a small amount of main reinforcement bars of lattice girder at the arch of a tunnel were pulled, and the calculation showed that the initial support structure should be compressed. To find out the reason for the tension of the main reinforcement, the geological radar was used to detect the cavity in the sprayed concrete layer at the tension position. In order to clarify the tension mechanism of the main reinforcement and the influence of factors such as the position and size of the cavity on the main reinforcement, numerical simulations were carried out. The results show that the cavity causes the eccentric compression of the shotcrete layer, resulting in moment of the lattice girder and the change of the stress distribution of the main reinforcement. The main reinforcement experiences tensile stress when the cavity size surpasses 3 m × 0.2 m, reaching a tensile stress of 81 MPa at a cavity size of 6 m × 0.2 m. Notably, the cavity located at the foot of the arch is more likely to produce substantial tensile stress on the primary reinforcement compared to those at the arch crown and waist. The research results provide a theoretical basis for the interpretation and analysis of tunnel lattice girder monitoring data. [ABSTRACT FROM AUTHOR]

Water and sand leakage (WSL) disasters frequently occur in underground engineering such as tunnels and foundation pits. The appearance of leakage port destroys the stable soil structure and leads to the leakage of soil particles in large quantities under the action of water flow and gravity, especially in gap-graded sandy soil layer. Therefore, model experiments on the WSL of gap-graded sandy soil with different grain size distributions are conducted by self-designed WSL simulation device. Moreover, the applicability of Peck curve and ellipsoid theory in estimation of the volume loss rate and influence radius of WSL in sandy soils is explored. Results show that GGS1 containing 20% coarse particles fails to form soil arch with 80.7% of sand leaked. However, GGS2 and GGS3 containing 40% and 60% coarse particles form soil arches in WSL with 13.5% and 10.9% of sand particles leaked, respectively. Moreover, the soil surface settlement decreases, while the settlement influence radius increases, as the content of coarse particles increases. The natural filter channel formed in sandy soils with higher coarse particle content is longer and wider. Finally, theoretical results are consistent with experimental results, which verifies the applicability of Peck formula and ellipsoid theory in the evolution of WSL. [ABSTRACT FROM AUTHOR]

The risk of arch foot instability arises in the application of the arch cover method when the surrounding rock is weak. To expand the application of this method, countermeasures are proposed, and construction feasibility is analyzed through a load–structure interaction model, a 3D numerical model, and monitoring data. A parametric analysis is performed to examine the influence of geological conditions and reinforcement parameters. Results indicate that the deformations of the support system decrease in a negative exponential form with the increase in the arch foot expansion coefficient, pile diameter, and prestress. The stress decrement is small when the arch foot expansion coefficient is 2.0. If the arch cover method is used for construction, the geological strength index of rock mass should be more than 45. When a metro station that crosses through a fault fracture zone is constructed by the arch cover method, the countermeasure design process must check whether the bearing capacity of the surrounding rock below the arch foot exceeds the stress state. If this condition does not exist, then checking should be performed again by considering the grouting reinforcement. If this condition that considers the grouting reinforcement holds, other reasonable arch foot reinforcement parameters should be applied, or the excavation method should be changed. [ABSTRACT FROM AUTHOR]

Backfill is used in the mining industry to improve the stability of underground openings and reduce the environmental impact due to the surface disposal of mine wastes. A critical issue for the design of backfilled stopes is the determination of the stress state in the backfill and surrounding rock mass. In recent years, much work has been conducted to assess the stresses in isolated backfilled stopes. Recent work performed by the authors indicates that the stress distribution in a backfilled stope may also be affected by the excavation of an adjacent opening. So far however, simulations of neighbouring stopes have been based on an elastic behavior for the rock mass, which may not reflect its actual response (especially under large stresses). This paper presents key results obtained from numerical simulations of two backfilled stopes excavated in sequence in an elasto-plastic rock mass. The simulations results illustrate the effects of the non-linear rock mass response and of other characteristics including stopes geometry (size and spacing) and depth, natural stress state, and backfill properties. These results indicate that, although arching effects tend to develop in all narrow stopes, the stress distribution in adjacent openings can be quite different for elastic or elasto-plastic rock mass behavior. The results presented here also illustrate the similarities and differences between the behavior of a single backfilled stope and of two adjacent stopes, depending on the rock mass properties and overall characteristics of the system. [ABSTRACT FROM AUTHOR]

The control of surrounding rock is a challenge faced during large-section tunnel construction, resulting in insufficient strength of the traditional support. Confined concrete arches with high strength and rigidity are suitable for controlling large-section tunnel surrounding rocks. To effectively control the soft surrounding rock of large cross-section tunnels, it is necessary to study the bearing characteristics and influencing mechanisms of confined concrete arches. A mechanical test on large-scale arch in traffic tunnels is conducted. The deformation mode and ultimate bearing capacity of the arch are analysed. The test results show that the deformation mode of the confined concrete arch is "the vault and bottom converge inwards, and the whole arch becomes flat". The maximum bearing capacity of the arch in the stable bearing stage is 830.7 kN, and the ultimate bearing capacity is 1157.2 kN. On the basis of laboratory tests, numerical simulations are conducted on different arch dimensions and cross-section parameters. The influence mechanisms of the section dimension and arch design parameters on the bearing capacity are clarified. As the section dimension increases, the load-bearing capacity of the arch decreases continuously. The ultimate bearing capacity of the arch with an on-site size is 784.5 kN, which is 32.2% lower than that of the arch in the laboratory test. A comprehensive evaluation index considering cost and bearing capacity has been established to select reasonable design parameters for confined concrete arches. Based on the above research results, engineering suggestions are put forwards, and the arch is applied in the Letuan tunnel, which effectively controls surrounding rocks. [ABSTRACT FROM AUTHOR]

Masonry arch structures are one of the oldest forms of construction of human civilization. These types of structures have been used since ancient times, and many old arch structures still stand without any major damage. The performance of masonry arch structures under static and dynamic loads is an active field of research, as these structures have architectural and cultural significance. The failure modes of the masonry arch depend on various factors like the type and shape of the arch, boundary conditions, presence of cohesion, etc. The behavior of the mortar-bonded arch can vary from the dry-jointed arches. This is due to the effect of tensile strength present at the joints. This is particularly true for arches with smaller spans and where the mortar is present or where cohesive materials are used. The present study is an attempt to understand the behavior of mortar-bonded masonry arch structures under static and dynamic loads. An experimental model of a masonry arch cast with small-scaled bricks was tested on the shake table under earthquake loads. A numerical model of the small-scale masonry arch was also developed in Abaqus and calibrated as per the experimental outcomes of the tests. Non-contact measurements were also performed in the present study during the shake table testing with the help of basic tools like a smartphone camera and video processing methods in MATLAB. The experiments and FE analysis showed that the mortar-bonded arch showed significantly more strength than the no-tension voussoir arch. [ABSTRACT FROM AUTHOR]

Despite the previous interpretations of the evolutionary scenarios of the Qatar Arch, the present study aimed to present a new complementary scenario to lay out the probable effects of another basement fault, corresponding to the physical shape of the Arch. A remote sensing study was carried out based on geological and geophysical data interpretations, obtained from some national and international databases, including GIS-based global geology data of Harvard University, the free-air gravity anomaly data from the World Gravity Map (WGM), and the airborne geophysical project of the National Geosciences Database of Iran (NGDIR). Results revealed that offshore extrapolation of the Trans Arabian-Bostaneh Fault (TABF) lineament through the morphological boundary of Hauterivian–Barremian (HB) formations and the offshore extrapolation of the Kazerun fault could produce a new complementary model for the Qatar Arch evolution. Based on the particular shape of the Arch (i.e., narrowing and uplifting to the south influenced by the Kazerun basement fault and the rotation of TABF), we can propose that these faults crossed each other after the Barremian age, created a particular shape of the Qatar Arch, and influenced beneath the Fars hinterland. The obtained geophysical gravity data also showed a good match between structural units and faults with maximum values corresponding to the Qatar Arch and minimum values relating to the thick sediment field in the Fars region. In conclusion, the present study contributes to a new proposition about exploring the possible faults and a new gas field situated in the interior territory of Iran. All of these interpretations will provide a new insight to improve the extant knowledge in the geology and petroleum evolution of the study area, such as the Plate tectonic events and the creation of possible reservoirs in future. [ABSTRACT FROM AUTHOR]

To study the effect of mining dynamic response characteristics on the footwall working face of the normal fault under the influence of the gob area, theoretical research, indoor experiment, and numerical simulation are adopted to analyze the stress manifestation characteristics, overburden movement, and energy evolution characteristics during the process of mining. The results show that: (1) In the process of mining toward the fault, the working face shows the change characteristics of "stable-activation mutation-final stability". At 20 m from the fault, the arch structure of the working face was damaged, fissures appeared near the high fault fracture zone, and the displacement of the overburden rock increased significantly; (2) the maximum value was reached at 4–8 m from the coal wall, and the superposition of tectonic stress and mining stress led to the concentration of the stress and energy accumulating on the top plate near the fault, and the data close to the gob area were even larger; (3) If the plastic damage zone of the high-level rock layer on the hanging wall and footwall of the fault appears to have a wide range of penetration, and the area formed between the shear displacement curve of the fault plane and the X-axis appears to have a significant enhancement, it is considered that the fault has been activated; (4) The size of the coal pillar of the fault is determined to be 40 m, and combined with the pressure unloading technique of the variable-diameter drilling hole, the validation is carried out through the micro-vibration monitoring, and the results of which can be used as a reference for the safety of the working face under similar conditions. [ABSTRACT FROM AUTHOR]

The evolution of the medial longitudinal arch (MLA) is one of the most impactful adaptations in the hominin foot that emerged with bipedalism. When and how it evolved in the human lineage is still unresolved. Complicating the issue, clinical definitions of flatfoot in living Homo sapiens have not reached a consensus. Here we digitally investigate the navicular morphology of H. sapiens (living, archaeological, and fossil), great apes, and fossil hominins and its correlation with the MLA. A distinctive navicular shape characterises living H. sapiens with adult acquired flexible flatfoot, while the congenital flexible flatfoot exhibits a 'normal' navicular shape. All H. sapiens groups differentiate from great apes independently from variations in the MLA, likely because of bipedalism. Most australopith, H. naledi, and H. floresiensis navicular shapes are closer to those of great apes, which is inconsistent with a human-like MLA and instead might suggest a certain degree of arboreality. Navicular shape of OH 8 and fossil H. sapiens falls within the normal living H. sapiens spectrum of variation of the MLA (including congenital flexible flatfoot and individuals with a well-developed MLA). At the same time, H. neanderthalensis seem to be characterised by a different expression of the MLA. A GM study diachronically examined evolution of the medial longitudinal arch and variation as expressed by the navicular bone, identifying navicular traits associated with particular locomotor behaviors, subsistence strategies, and foot types [ABSTRACT FROM AUTHOR]

In this paper, a simplified method for predicting rock mass resistance against tensile forces from rock anchors (anchor) is presented. The interaction of anchors and rock mass was investigated using three-dimensional discontinuous numerical modelling. Several patterns of rock discontinuities were assumed in the numerical modelling while a single anchor is embedded in it. The numerical results show that the existence of a discontinuity set sub-parallel to the anchor significantly improves the rock mass resistance against the tensile force from the anchors. This phenomenon is due to the rock block interlocking at the sub-parallel discontinuity set. Rock block interlocking generates a zone of stress concentration inside the rock mass which has an arch shape (i.e., a pressure arch), resisting against the anchor's tensile force. The load-bearing capacity of the pressure arch plays a significant role in the resistance of the rock mass against the forces from the rock anchor. A voussoir beam analogy was utilised to study the load-bearing capacity of the pressure arch. A simplified analytical approach was developed to assess the load-bearing capacity of the voussoir beams. Then, it was used in combination with the weight of the mobilised rock mass by the anchor to assess the maximum anchoring resistance of the rock mass (anchoring capacity). The suggested method was calibrated by numerical modelling and relevant published pull-out test results. The technique developed in this paper shows the significance of rock block size, shear behaviour of rock discontinuities, Young's modulus of the rock mass, and uniaxial compressive and tensile strength of the intact rock in anchoring capacity of rock masses. Highlights: A theoretical framework is presented on how rock mass and rock anchors interact based on numerical modelling. An analytical method is developed to calculate the anchoring capacity of a rock mass which has at least one joint set sub-parallel to the anchor. The importance of the rock block size and the shear behaviour of rock discontinuities in determining the anchoring capacity of the rock mass is discussed. [ABSTRACT FROM AUTHOR]

A smooth shaft production process is important to ensure the safe and efficient development of mineral resources. Due to the influence of ore rock and the mismatch between rock size and ore pass design, an arching phenomenon occurs frequently during actual ore pass release, stagnating production. Therefore, an ore pass release simulator with a freely variable ore pass angle and height is designed and used to conduct a four-factor, five-level orthogonal ore pass release experiment. An analysis is performed to determine the influence of four factors—ore particle size, ore moisture, ore pass inclination and slip height—on the probability of ore pass arching; from there, an ore pass arching probability equation is constructed and the characteristics of the ore pass arching location are clarified, effectively predicting the probability of ore pass arching and providing an effective basis for handling arching events within an applicable range. This analysis effectively predicts the probability of ore pass arch within the applicable range, and provides an effective basis for handling ore pass arch events. [ABSTRACT FROM AUTHOR]

In fact, Korsmeyer sees authenticity or genuineness as contributing to several forms of value including scholarly value and ethical value.[12] Fakes, after all, are unable to stand as historical evidence. Indeed, the value of the formation will be similar to the value held by the replica Ark of the Covenant; despite being non-genuine in one sense, both are extendedly tied to religious and cultural practices in ways a person might appreciate. A judgement of authenticity confirms this is true, but authenticity is not the I source i of that ethical value any more than the value of an authentic bucket of motor oil is conferred by I its i "authenticity". Korsmeyer also leans heavily on authenticity and related concepts during her analysis of the aura-related value in I Things: In Touch with the Past i and I will be drawing on many passages from this text in order to inform and support this paper's discussions.[6] However, my development and eventual criticisms of the Authenticity Thesis during section 1 should not necessarily be understood as an exegesis of Korsmeyer's account. [Extracted from the article]

In order to meet the terrain adaptability, flexibility, and stability requirement of the agricultural power chassis when driving in complex terrain and narrow fields in hilly and mountainous areas, an arch waist power chassis suitable for a narrow plot with strong ground adaptability is designed. On the undulating road surface, the longitudinal pitch of the track can be used for active and passive ground copying to exert the maximum driving force. Through the theoretical analysis of the whole machine, it is obtained that the minimum turning radius of the chassis is 568.5 mm between the two rear wheels, which is about 34.12% of the length of the whole machine. The longitudinal uphill slip angle α φ is 26.9–42.84°, and the longitudinal downhill slip angle α φ ′ is 29.28–43.7°. Finally, the performance test of the whole machine is carried out. The test results show that the arch waist power chassis has a minimum turning radius of 1230.7 mm in field driving, which has good steering maneuverability and can adapt to the narrow operating environment in hilly and mountainous areas; the longitudinal downhill slip angle is 32°, and the longitudinal uphill slip angle is 28°. The longitudinal downhill slip angle is about 1.14 times the longitudinal uphill slip angle, and the lateral slope slip angle is 27°, which meets the requirements for stable operation in hilly and mountainous terrain. [ABSTRACT FROM AUTHOR]

Despite the benefits of canal coverage structures, they may turn out to be a significant reason of decreasing canals conveyance efficiency if they are subject to blockage. The difficulty of removing wastes from closed canals further exaggerates the problem. This study investigates the effects of blockage in canal coverage structures, focusing on various cross-sectional shapes and blockage ratios. Seven coverage cross-section shapes, namely the square box, pipe, pipe arch, ellipse, arch, conspan arch, and rectangular box, were studied in combination with 10 different Froude numbers and 10 different blockage ratios. An experimental setup was used in the study along with the HEC-RAS 1D numerical model, which was evaluated through a series of comparative tests. The study demonstrated that blockage in a canal coverage structure and its extent significantly impairs the structure's hydraulic performance, leading to an increased head loss ratio and a reduced velocity ratio. The extent of this reduction varied with different coverage shapes, and the sensitivity to blockage was found to be the highest in the square box section, followed by the pipe section at the same design Froude number. A crucial threshold was identified at a blockage ratio of 30% where the performance of coverage structures started to decline sharply, indicating a key maintenance point. Among the shapes studied, the pipe arch had the best performance in terms of head loss reduction, while a rectangular box with a height to width ratio of 2:3 was found to be a close second. Considering the construction complexities associated with the pipe arch, the rectangular box is recommended as the most practical and efficient option for canal coverage structure design. The findings from this study provide valuable insights for engineers and decision-makers involved in canal management and infrastructure planning. [ABSTRACT FROM AUTHOR]

The 3D deformation mechanism of flexspline (FS) is the foundation of harmonic drive. In this paper, a novel methodology based on Rayleigh-Ritz method (RRM) is proposed to solve the three-dimensional elastic deformation of FS. First, the analytical model of RRM for 3D elastic deformation is formulated. A three-dimensional displacement trial function is designed according to the structure and constraints of FS. The RRM improves the accuracy of the solution by increasing the number of terms of the trial function. According to the completeness of the trial function, the real elastic deformation state can be approached arbitrarily in theory. The convergence efficiency of the actual iteration process is greatly affected by the iteration strategy. Therefore , an accelerated convergence strategy is proposed to overcome the drawback of poor convergence rate in the general iterative process. The elastic deformation characteristics of FS are studied by the new method, and a sensitivity analysis of structural parameters is performed. The results demonstrate that the new method is highly accurate and efficient. The radial deflection is slightly arch-shaped along the axial direction, reaching the maximum value near the axial position of the displacement constraint. The tangential deflection is 0 on the symmetry plane, and the value is smaller when it is farther away from the symmetry plane, which reflects the tendency of the gear tooth deflecting towards the major shaft section of the wave generator. The descending order of sensitivity of structural parameters affecting taper deformation is cylinder length (Pl), radii difference (Pd), cylinder thickness (Pt), hole radius (Ph), fillet radius (Pf) and gear rim width (Pw). The descending order of sensitivity of structural parameters affecting tooth skewness is Pl, Pd, Ph, Pf, Pw and Pt. [ABSTRACT FROM AUTHOR]

This article is a retrospective analysis of postmortem computed tomography scans of ossification stages of the anterior and posterior intra-occipital sutures, the anterior arch of the atlas, and the neurocentral junction of the axis. We also analyzed the development of secondary ossification centers in the proximal humeral, femoral, and tibial epiphyses, and the distal femoral and tibial epiphyses. Additionally, the development of primary ossification centers in the wrist and metacarpals, and maxillary and mandibular deciduous tooth maturation. A total of 58 cadavers (35 males, 23 females), whose age ranged from 3rd month of pregnancy to 14 years, were analyzed. The results of this study show that analysis of synchondrosis closure, primary, and secondary ossification center development and deciduous tooth changes are a good tool for age estimation in subadults group (fetuses, newborns, infants, and children). The results of the study in a Polish population are consistent with those reported by other authors. [ABSTRACT FROM AUTHOR]

In order to solve the problem of large deformation at the intersection of deep large section soft rock roadway, this paper takes the intersection of kilometer-deep roadway in the Wanfu Coal Mine as an engineering example and applies Negative Poisson's Ratio (NPR) steel anchor cable in roadway support for the first time. By combining numerical simulation indoor test, theoretical analysis and field test, the deformation mechanism of surrounding rock at the intersection of deep-buried roadway was analyzed, and the control strategy with micro NPR steel anchor cable as the core was put forward. Through numerical simulation, the numerical analysis model of roadway intersection with different intersection angles and excavation sequence was constructed, and the impact of two key variables of rake angle and excavation sequence on the stability of surrounding rock at roadway intersection was studied. The optimal dip angle is 90° and the optimal excavation sequence was determined as pump house -pump house passage - substation. The mechanical properties of the micro-NPR steel anchor cable were studied through the static tensile test in the laboratory. The results showed that the micro-NPR steel anchor cable showed high constant resistance, uniform tensile, no yield platform, and no obvious necking phenomenon during breaking. Through theoretical derivation, it was calculated that the vertical stress of roadway intersection is 45 MPa, and the bearing capacity of superposed arch composed of micro NPR steel anchor cable is 1257 kN, which is enough to guarantee the overall stability of intersection. Support application test and monitoring were carried out on site, and it was verified that the combined support strategy of short and long micro NPR steel anchor cable has a good control effect on large deformation of surrounding rock at intersection, which provides a new support material and support means for the safety and stabilization control of surrounding rock at intersection. [ABSTRACT FROM AUTHOR]