In this study, the FLAC3D finite difference numerical software was employed to simulate a geotechnical engineering project, establishing scenarios with concrete and steel pipe piles for support simulation. The analysis focused on the reinforcement effects provided by different types of piles on the geotechnical project. It was found that the reinforcement effects on the soil varied significantly between the pile types. Under the support condition of concrete piles, the maximum soil settlement observed was 4.12 mm, with a differential settlement of 3.19 mm. For steel pipe piles, the maximum soil settlement was reduced to 2.38 mm, with a differential settlement of 2.19 mm, indicating a superior support effect compared to that of concrete piles. Stress concentration phenomena were observed in the piles, becoming more pronounced when pile-soil friction was considered. The substitution of concrete piles with steel pipe piles led to an intensified stress concentration phenomenon in the soil surrounding the piles. The soil undergoing support from concrete piles exhibited the largest plastic deformation, whereas soil supported by steel pipe piles showed less plastic deformation. Consequently, it is concluded that steel pipe piles provide a superior support effect over concrete piles in terms of geotechnical engineering reinforcement.
Seismic performance is a critical consideration in the design and assessment of reinforced concrete bridges. Ensuring the structural integrity and safety of bridges under seismic loadings is essential to protect public safety and maintain the longevity of these vital infrastructure components. The objective of this research study was to evaluate the seismic performance of a multi-span reinforced concrete bridge located in Pan Borneo Highway Sarawak. The non-linear static pushover analysis provided valuable insights into the bridge's load resistance. It determined that the bridge could withstand a base shear force of up to 30,130.899 kN before collapsing, indicating its high structural capacity. The capacity curve analysis further demonstrated the ability of bridge to endure spectral accelerations of up to 4.44 g (43.512 m/s$^2$), indicating its robustness against high-intensity ground motions. In addition, the non-linear static time history analysis considered three ground motions and their effects on the bridge's structural performance. The study highlighted the bridge's sensitivity to different external forces, with varying responses observed under different ground motions. Notably, the recorded joint acceleration and displacement values were found to be within acceptable limits, ensuring immediate occupancy and life safety for bridge users. The research study successfully evaluated the seismic performance of a reinforced concrete bridge in Pan Borneo Sarawak using non-linear time history and pushover analyses. The results demonstrated the bridge's satisfactory capacity to withstand seismic loadings. The utilization of CSIBridge software provided valuable insights into the bridge's structural integrity and behavior under seismic conditions. These findings contribute to the advancement of bridge engineering practices.
Traditional analyses of tunnel reliability, which employ deformation values, such as surface settlement, crown settlement, and arch shoulder settlement, as instability indicators, fail to accurately depict the failure state of tunnel lining structures. In addressing tunnel instability induced by the failure of lining structures, the limit strain theory is introduced, designating shear strain penetration failure of the lining structure as the criterion for tunnel instability. A novel method for studying tunnel reliability, integrating neural network response surface methodology and Monte Carlo simulation, is proposed. The feasibility of the limit strain theory in reliability analysis is validated through the calculation of instability probabilities for specific tunnel projects, offering a fresh perspective on tunnel reliability assessment. Sensitivity analysis of rock mass parameters reveals that an increase in the variability of these parameters elevates the probability of tunnel instability and the shear strain value at the arch waists. Among these parameters, the variability of the modulus of elasticity (E) exerts the most significant impact on the probability of tunnel instability.
Glued laminated timber (glulam), a composite material fabricated by bonding multiple wood layers, is engineered to support specific loads, offering reduced product variability and diminished sensitivity to inherent wood characteristics, such as knots. This technology facilitates a wide array of architectural designs, rendering it a popular choice for load-bearing elements across diverse construction projects, including residential structures, storage facilities, and pedestrian overpasses. Over time, exposure to various environmental conditions leads to the degradation of these structural components, necessitating periodic reinforcement to maintain their strength properties. Recent advancements have seen the adoption of fiber-reinforced polymer (FRP) for the reinforcement of columns and beams, a departure from traditional strengthening methods. This study focuses on the connection of column-beam joints using an array of steel fasteners, subsequently reinforced with FRP. Rotational tests were conducted on these fabricated connections, followed by a comprehensive analysis using the finite element method (FEM). Results indicate that connections reinforced with FRP exhibit a significant enhancement in load-carrying capacity, energy dissipation, and stiffness compared to their unreinforced counterparts. Specifically, the load-carrying capacity showed an increase of 25-39%, energy dissipation capacity augmented by 64-69%, and stiffness values rose by 2-7%. These findings underscore the efficacy of FRP reinforcement in improving the structural integrity and performance of glulam column-beam connections, offering valuable insights for the design and renovation of wood-based construction elements.
In rock masses, internal defects such as joints, faults, and fractures are pivotal in determining mechanical behavior and structural integrity. This investigation, employing the discrete element numerical simulation technology of GDEM, examines the mechanical attributes of single-fractured sandstone under standard triaxial compression. The study focuses on how fracture inclination angle and confining pressure affect crack propagation within the rock. It is observed that an increase in both fracture inclination angle and confining pressure correlates with a reduction in the tensile stress growth rate near the fracture, indicative of inhibited crack propagation. A notable transition in the failure mode of the sandstone samples is identified, shifting from tensile-shear to predominantly shear failure. This shift is more pronounced under varying confining pressures: Low confining pressure conditions show a prevalence of tensile-shear damage units in proximity to the fracture, while high confining pressure leads to a dominance of shear damage units. These findings contribute to a deeper understanding of fracture mechanics in rock materials and have significant implications for geological and engineering applications where rock stability is critical.
An innovative approach utilizing 3D laser scanning technology has been introduced in open-pit mining for capturing spatial data of blast piles. RANSAC for plane fitting and DBSCAN for clustering are applied to outline rock block contours accurately. Quick calculation of rock block volumes and maximum particle sizes is enabled through 3D convex hulls and Oriented Bounding Boxes (OBB). Delaunay triangulation of 3D point cloud data is used to create a detailed mesh model for precise volume estimation of blast piles. Indoor testing revealed relative errors of approximately 4.61% for block volumes and 4.75% for particle sizes, while field applications showed an average rock block identification accuracy of 80.4%, increasing with block size. Estimated versus actual blast pile volumes showed a relative error of 4.85%, with computational errors for the pile's height, forward throw distance, and lateral extent being 2.92%, 3.91%, and 4.29%, respectively.
Building upon the foundations of classical fractional derivatives, the general fractional derivative emerges as a significant advancement in the development of constitutive models, especially for materials with complex properties. This derivative distinguishes itself through a kernel function of variable form, enabling it to encapsulate diverse characteristics of the creep process more effectively than its classical counterpart. This study introduces a general-variable order fractional creep constitutive model, ingeniously linking the order of the fractional derivative to Talbot gradation, which describes the aggregate gradation of cemented backfill materials, alongside dosage and confining pressure parameters. The model's innovative design synergizes the kernel function's diversity from the general fractional derivative with the phase adaptability inherent in the variable-order derivative. This integration permits a comprehensive description of each stage of the creep curve for cementitious filling materials in varying compositions, leveraging the Gamma function's properties within the positive real number domain. The model's rationality and validity are substantiated through a comparative analysis between experimental creep curves and theoretical predictions, affirming its relevance and accuracy in practical applications. This approach represents a notable contribution to the understanding of cemented backfill materials' behavior, offering a robust tool for engineering analysis and design.
This study examines innovative box-plate prefabricated steel structures, where stiffened steel plates serve as primary load-bearing walls and floors. In contrast to traditional stiffened steel plate walls, which typically exhibit significant hysteresis, pronounced out-of-plane deformation, and rapid stiffness degradation, these advanced systems demonstrate superior performance. A pivotal feature of these structures is the intensive use of welding to connect stiffened steel plates during assembly. This study introduces a novel composite stiffened steel plate wall, addressing concerns of traditional systems, and executes a comprehensive numerical simulation to assess the influence of welding on joint integrity and overall structural performance. It is observed that the height-to-thickness ratio of steel plate walls significantly influences load-bearing capacity, with a lower ratio yielding enhanced capacity. However, the stiffness ratio of ribs is found to have minimal impact. An increase in bolt quantity and density correlates with improved ultimate bearing capacity. Moreover, the adoption of staggered welding techniques bolsters shear strength, though the positioning of welds has negligible influence on this parameter. The number of welded joints moderately affects shear strength, while the size of staggered welding joints is identified as a crucial factor, with larger sizes leading to more pronounced reductions in shear strength. This study highlights the importance of construction details, particularly in welding practices, in the structural integrity and performance of box-plate prefabricated steel structures. The findings offer significant insights for optimizing design and construction methodologies to maximize the load-bearing capacities of these innovative systems.
In the context of layered inclined surrounding rock in roadways, this study presents a comprehensive analysis focusing on the asymmetrical deformation characteristics inherent to such geological structures. The intersection of layered surrounding rock with roadways forms the basis for constructing a deformation partition model, encompassing distinct sub-regions around the roadway. This model facilitates a detailed mechanical analysis, wherein the stress exerted on rock formations within each sub-region is meticulously examined. Consequently, specific mechanical formulas correlating to the stress in different sub-regions are established. This approach yields insights into the failure modes of the layered surrounding rock across various sub-regions. Notably, the roadway's high side predominantly exhibits tensile failure, whereas the low side is characterized by shear failure. The application of the Goodman model enables a simulation of interlayer slip occurring between the surrounding rock of the roadway, distributed across different partitions. This study delineates the deformation of the layered inclined surrounding rock road-way as a process with pronounced temporal characteristics. The progression of deformation and failure in the surrounding rock typically initiates at the tangent point between the roadway roof and the rock layer, extending to the roadway floor, the high-top bottom angle, and subsequently the low-top bottom angle. This sequence culminates in the development toward the high-top shoulder angle. The research further establishes a direct correlation between the onset of asymmetrical deformation and the angle of shear stress on the roadway surface relative to the inclination of the rock formation; a smaller angle precipitates an earlier onset of this deformation.
Tunnel linings, depending on their geographical locations, are exposed to various magnitudes of seismic loads. Ensuring that these linings resist seismic perturbations without exhibiting failures, such as crack initiation or propagation, is paramount. In the presented study, the structural stability of tunnel linings under pronounced seismic excitations was rigorously evaluated. Seismic excitations, in compliance with the IS 1893: 2002 code for both zone II and zone III conditions, were administered. Computer-Aided Design (CAD) modelling, static structural, and harmonic excitation analyses were meticulously conducted via the ANSYS finite element analysis (FEA) simulation package. From these comprehensive analyses, critical zones within the tunnel linings were identified under varying excitation frequencies. It was observed that, predominantly, these critical regions are situated at the corners of the tunnel linings, specifically in the bottom areas. Distinct maximum and minimum induced normal stresses within the tunnel structure were ascertained. Under a seismic excitation of .1g, a maximum reaction force of 1232.1 kN was derived. Conversely, for a seismic excitation of .16g, the reaction force peaked at a 1Hz frequency with a magnitude of 1971.3 kN. These findings furnish pivotal insights into the structural performance of tunnel linings when subjected to seismic disturbances, providing tunnel engineers and designers with invaluable knowledge to augment the resilience and safety of tunnel infrastructures.
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