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.
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.
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.
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.
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.
Open Access
Journal Metrics
Journal Overview
Associated Journals