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With the development of the society the large span bridges and spaces emerge continuously in the world. And the space structures are developing towards spans. The traditional building materials are heavy due to their high density and insufficient strength, which limited the development of large-span space structures. In order to build the mechanical performance model a new type of composite structure with CFRP bars as the main force bearing body is proposed, the feasibility of the proposed structure is analyzed, and six design methods for working conditions are selected., and the steel plates are used as the node connections. This article does not consider the slip problem between steel plates and CFRP bars, so the steel plates are set as rigid bodies and a new type of composite structure with end supports is designed. ABAQUS finite element analysis is used to study the axial compression and pure bending mechanical properties and failure process analysis of rod steel composite components. The simulation study on the macroscopic mechanical properties and microscopic mechanisms of failure phenomena, including the failure process analysis of the model’s load displacement, load deflection, of CFRP bar-steel composite components is carried out in the present investigation.

A weak interlayer zone (WIZ) is a poor rock mass system with loose structure, weak mechanical properties, variable thickness, random distribution, strong extension, and high risk due to the shear motion of rock masses under the action of tectonism, bringing many stability problems and geological hazards, especially representing a potential threat to the overall stability of rock masses with WIZs in large underground cavern excavations. Focusing on the deformation and failure problems encountered in the process of excavation unloading, this research proposes comprehensive in situ observation schemes for rock masses with WIZs in large underground cavern on the basis of the collection of geological, construction, monitoring, and testing data. The schemes have been fully applied in two valuable project cases of an underground cavern group under construction in the southwest of China, including the plastic squeezing-out tensile failure and the structural stress-induced collapse of rock masses with WIZs. In this way, the development of rock mass failure, affected by the step-by-step excavations along the cavern’s axis and the subsequent excavation downward, could be observed thoroughly. Furthermore, this paper reveals the preliminary analyses of failure mechanism of rock masses with WIZs from several aspects, including rock mass structure, strength, high stress, ground water effects, and microfracture mechanisms. Finally, the failure particularities of rock masses with WIZs and rethink on prevention and control of failures are discussed. The research results could provide important guiding reference value for stability analysis, as well as for rethinking the excavation and support optimization of rock masses with WIZs in similar large underground cavern under high geostress.

Shear-box experiments, Rock Failure Process Analysis (RFPA) simulations, and box-counting fractal analysis on rock-like models are conducted to investigate the influence of intermittent artificial crack density on the shear fracturing and fractal behavior of rock bridges in jointed rock slopes. The artificial crack geometry of the conceptual rock bridge model is a combination of two edge-notched artificial cracks and imbedded artificial cracks with different intermittent artificial crack densities. By numerical shear-box tests, deep insight into the mesoscopic mechanism of crack evolution is gained, and the simulated failure patterns are in accordance with experimental results. Three types of failure patterns are identified: shear mode, mixed shear/tensile mode, and tensile mode. The RFPA simulations demonstrate that macroscale shear cracks form as damage belts consisting of many tensile/shear mesocracks, as typically observed in microscopic experimental work. The failure pattern is mostly influenced by the intermittent artificial crack density, whereas the peak shear strength is related to the failure pattern. As the intermittent artificial crack density increases, the failure pattern changes from shear mode to mixed shear/tensile mode and then to tensile mode, resulting in a decrease in the peak shear strength. The regression analysis shows that the relationship between the peak shear strength and intermittent artificial crack density can be expressed by an exponential decay model. Furthermore, digital image processing and box-counting fractal analyses are performed on the shear fracture surfaces of the physical and numerical models to describe the fractal behavior. The relationships between the fractal dimension and peak shear strength are analyzed, and strong correlations that display an exponential decay function are found.

Nowadays, decision-making process is faced with different challenges. There are many aspects that must be considered and planned, especially programs in the automotive industry that is associated with human vital factors are not structured. Therefore, managerial and engineering techniques should be used to solve the existing problems. In this regard, the process failure mode and effects nalysis (PFMEA) technique is one of the ways to assess the potential product or process failures and their effects, designs from the beginning to the end of the product life cycle, and identifies actions to eliminate the failures or reduce their effects. The well-known method for piriortizing these failures is risk priority number (RPN). Because the RPN has problems in prioritization of critical processes, a new approach is needed to remove these problems.Thus, in a real case study, first PFMEA technique has been implemented with the help of multidisciplinary teams for the parts of Peugeot 206, Peugeot 405 and Samand (three types of automobiles produced by Iran-khodro company) and affected factors have been obtained as an interval. Then, interval data envelopment analysis (DEA) have been used to prioritize and analyze all failures that are identified by the PFMEA technique for every part. Finally, by combining the results of the interval DEA and Grey relational analysis (GRA), the manufacturing processes are prioritized based on their criticality. Moreover, the proposed actions for all the items associated with each process are provided to prevent some potential failures. The results show that pouring and core making are the most crucial processes in this study, respectively. According to the proposed approach, the decision makers may determine critical processes and plan and do appropriate actions for removing failures or reducing their effects.

With an increasing number of multi-seam mining projects, the problem of strata movement caused by multi-seam mining has attracted increasing attention. Previous studies have shown that the rock failure mechanism for multi-seam mining is obviously different from single-seam mining. When a lower coal seam is being mined, two issues are apparent: the activation that the upper goaf will suffer and the difference in the break mechanism of the stratum between single-seam and multi-seam mining. The research regarding these two issues is still inadequate. In this paper, a physical model experiment was used to simulate the full longwall mining process of multiple seams. Then, the failure mechanics of the stratum and the influence of mining the lower coal seam on the activation of the upper goaf are discussed under the condition that the upper coal seam has been fully mined. The results show that a part of the fracture zone that formed by mining the upper coal seam will be converted into a caving zone when the lower coal seam is mined. In multi-seam mining, the cracks in the overlying fractured rock mass will widen and propagate upward. During the process of mining the lower coal seam, the interburden rock mass presents a typical plate bending failure, and the break location is greatly affected by the distribution of the periodic weighting in the upper coal seam mining. Multi-seam mining will cause the surface subsidence trough produced by upper coal mining to move towards the end of the mining panel. The mechanism of rock stratum movement revealed by the test has a certain practical guidance for the control of roof pressure in multi-seam mining and the subsidence of surface.

Steep rock slopes are vulnerable to failure under complex geological and environmental conditions, posing serious risks to infrastructure and human safety. Conventional numerical techniques of slope stability, including the limit equilibrium method (LEM), the finite element method (FEM), and the discrete element method (DEM). They often struggle to simulate progressive failure involving the rock transition from a continuous to a discontinuous state. To overcome these limitations, this study proposes an integrated finite–discrete element method combined with the gravity increase method (FDEM-GIM). Unlike conventional approaches, this framework automatically identifies the critical failure surface and calculates the corresponding factor of safety (FoS), while explicitly simulating the full progressive failure process. In a case study from the upper Lancang River region, the simulations showed a clear progressive failure sequence characterized by slope toe cracking, upward crack propagation, tensile deformation, and eventual global instability and rock mass accumulation. Comparisons with LEM and DEM produced similar FoS values, but only the FDEM–GIM framework reproduced the full spatial and temporal evolution of damage and movement. Overall, this research indicates that the FDEM–GIM framework is effective for long-term stability assessment of steep rock slopes in complex geological settings and can support reinforcement design and safety management.

Combing macroscopic experimental method and mesoscopic numerical method, this study analyses the strain-softening behaviours of granite and sandstone. From the macroscopic perspective, the stress–strain curves of granite and sandstone under different confining pressures are studied by laboratory triaxial compression test. Variations of post-peak reduction modulus and critical plastic shear strain versus confining stress are obtained. Evolution of strength parameters at peak, residual and strain-softening stage are proposed. Then a method to develop the strain-softening model of hard and soft rocks is presented. From the mesoscopic perspective, based on the laboratory test results, the parameters of discrete element method PFC for the samples of the granite and sandstone are calibrated. Comparing the basically consistent results of laboratory experiment and numerical simulation, the feasibility of discrete element method is verified. Evolutions of mesoscopic crack propagation and mesoscopic particle displacement field in the complete failure process are analysed. Typical stresses of granite sample and sandstone sample in the failure stage are investigated. Above combined macroscopic experimental method and mesoscopic numerical method systematically analyse the characteristics of hard rock and soft rock in the strain-softening stage. Failure process and mechanical property of hard rock and soft rock are revealed at the macroscopic and mesoscopic levels. The initiation and propagation process of micro-cracks in rock are thoroughly investigated. The research results provide a scientific foundation for the analyse of strain-softening behaviour of hard rock and soft rock. The result shows that both the mesoscopic numerical method and macroscopic experimental method indicate that the failure pattern of sandstone is influenced by both confining pressure and axial stress, while granite is mainly affected by axial stress.

Colluvial landslides develop in loose Quaternary deposits, with deformation generally being progressive and crack development dominant in the sliding mass surface layer. With the Tanjiawan landslide in the Three Gorges Reservoir (China) as a case study, field investigations, deformation monitoring, and groundwater level monitoring data were integrated to analyze the landslide deformation characteristics and elucidate the influence of cracks on its deformation. We used numerical simulations, including the finite element and discrete element methods, for investigating the progressive deformation mechanism of rainfall-triggered landslides in the accumulation layer and predicting the failure process. The results indicated that crack formation instigated a preferential seepage channel in the shallow layer of the sliding mass, rainfall infiltration along cracks generated water pressure, and the landslide gradually morphed from a stable into a “step-like” progressive deformation state. Preferential flow inside the cracks effectively elevated the groundwater level within the landslide, and either the number or depth of cracks significantly affected the groundwater seepage field, thereby influencing slide stability. Geological conditions controlled the deformation and failure processes of each landslide section. The uplifted bedrock on the right side blocked the sliding process of the rear sliding mass, and the middle and front sliding masses moved faster but the sliding distance was shorter. The deformation trend is deformation, crack formation, preferential flow occurrence, crack extension, and deformation. The ultimate cause of failure was a steep rise in groundwater level following short duration heavy rainfall or long duration light rainfall.

Fiber length and fiber-to-fiber bonding effects on tensile strength and fracture toughness of kraft paper have experimentally been investigated. Laboratory sheets were made from kraft pulp, each with a distinct set of fiber lengths. Additionally, the fiber–fiber bond strength was improved by carboxymethyl (CMC) grafting. The tensile strength and work of fracture toughness results were compared to predictions from a shear-lag model which considers the fiber–fiber bond shear strength, the fiber tensile strength and fiber pull-out work. The tensile strength and fracture work for papers with weak fiber–fiber bonds increased with fiber length consistent with the shear-lag model. CMC-treated fibers provided strong fiber–fiber bonds. Papers made from such fibers displayed high strength and work of fracture independent of fiber length which indicates that the failure process is governed by fiber failures rather than bond failures. The fracture toughness, expressed as the critical value of the J-integral, increased strongly with fiber length for both untreated and CMC-treated papers. The results show that long fibers and CMC addition are extremely beneficial for improving the fracture toughness.

In rock engineering, the weakening effects of water on the stressed rock are nonnegligible. This paper studied the microstructure deterioration processes of sandstones under stress and stress-water coupling by real-time computed tomography (CT) technology and compared the difference in these two processes. Firstly, the real-time CT tests were performed on the dry and saturated sandstones during the uniaxial compression to study the progressive deterioration of sandstones caused by stress and stress-water coupling, which were further quantitatively described by porosity. Then, the equivalent radius was introduced to analyze the real-time pore structure characteristics of sandstones under stress and stress-water coupling. Finally, the difference in failure patterns of sandstones under stress and stress-water coupling was compared. The results show that the real-time CT images intuitively present the continuous changes of spatial morphology of defects in sandstones under stress and stress-water coupling. During the uniaxial compression, the porosities of dry and saturated sandstones decrease at first, then increase slowly and finally increase rapidly. However, as the increase of stress, the variation in porosity, shifting of pore size distribution curve and change of maximum equivalent radius interval of saturated sandstone are more significant, indicating that even under the same stress state, the water aggravates the microstructure deterioration of sandstone, thus leading to the reduction of bearing capacity of sandstone. In addition, the failed region of saturated sandstone is mainly composed of multiple shear and tensile cracks, which presents the typical tensile-shear composite failure.HighlightsReal-time CT tests were performed on sandstone during uniaxial compression.Real-time progressive failure process of sandstone was observed.Real-time pore distribution characteristic of sandstone was studied.Stress-water coupling effects on failure of sandstone were discussed.