Analysis of the crisis-deformed state and dynamic operation of reinforced concrete sleepers

Due to the vibration (dynamic) effect on the path of the load from the rolling stock, reinforced concrete sleepers cannot withstand. Hidden and obvious defects appear in them, sometimes leading to their complete destruction. The article presents the results of a computational analysis of prestressed reinforced concrete sleepers performed using finite element mechanical and mathematical modeling in the ANSYS 2021 R2 program. Comparative strength static and dynamic calculations were performed for experimental sleeper samples of “version 1 concrete grade B40” (type Sh-1) and “version 2 concrete grade B50” (type SH-2). The results of laboratory and full-scale (operational) tests of prestressed reinforced concrete sleepers after their installation on experimental sections of the railway line are presented. The purpose of this study was to identify the main causes of cracking and failure of reinforced concrete sleepers, in order to produce improved samples of prestressed concrete sleepers. The economic development of the railways of the Republic of Kazakhstan, as well as the operational safety of passengers and cargo, directly depends on this

Analysis and study on the ballistic design of small-caliber grenade anti-UAV

With the rapid development of UAV technology, the use of unmanned weapons on the modern battlefield has innovated the combat mode and changed the form of warfare. In order to ensure national security and deal with potential war risks, it is imperative to carry out research on anti-drone weapons and equipment. Compared with the electromagnetic signal jamming and interception network anti-UAV technology, based on the existing small-caliber grenade launch platform, the technology of using projectile explosion fragments and shock waves to destroy the enemy's UAV equipment has the advantages of lower cost, faster research and development, more complete damage and higher fault tolerance. Based on fluid mechanics, projectile design theory, internal and external ballistics theory and numerical simulation technology of modern weapon systems, this paper reasonably optimizes the shape of small-caliber grenades, and uses the characteristics of prefabricated fragmentation explosion to damage different parts of the UAV, so as to achieve the effect of anti-UAV

Optimal control of lane changing problem of intelligent vehicle

Lanes changing is one of the basic behaviors of vehicle driving, which has a significant impact on road traffic safety and stability. Aiming at the problem of slow convergence rate in solving the optimal control problem of vehicle lane changing, an optimal lane changing control method based on hp adaptive pseudospectral method is proposed. By establishing a vehicle kinematic model, boundary constraints, and path constraints, combining with the physical process of vehicle lane changing the proposed method discretizes the control and state variables to transform the multi constraint optimal control problem into a nonlinear programming problem and the minimum vehicle lane changing time is set as the performance objective function. And also, the proposed method is compared with traditional solving methods. The simulation results show that the proposed method can effectively solve the optimal feasible lane changing trajectory and complete the lane changing maneuver process in the shortest possible time

Review of chemical methods for road pavement stabilization: prospects for application in Uzbekistan

This article provides an overview of methods for stabilizing the subgrade soils of road pavements using nanomaterials and polymer additives. A theoretical‐comparative analysis is performed on both traditional stabilization methods and modern approaches that employ nanosilica, nanoclays, carbon nanotubes, and various polymers. The mechanisms of action of the stabilizers and their influence on the physico mechanical properties of soils are examined, along with the advantages and disadvantages of each method. Particular attention is devoted to the specific climatic and geological conditions of Uzbekistan. Based on an analysis of the literature and modeling results reported by both domestic and international researchers, recommendations are made for selecting optimal stabilization methods for different soil types and climatic zones in Uzbekistan. It should be noted that this study is a review and does not present the results of original experiments

Mechanical properties of nano-SiO2 modified ultra-high-performance concrete

This study experimentally investigates the effects of varying nano-silica (nano-SiO2) contents on the mechanical properties of ultra-high-performance concrete (UHPC) hardened paste, focusing on compressive and flexural strength improvements. Nano-SiO2, owing to its high surface area and reactivity, has potential to enhance UHPC performance by filling micro-pores and promoting cement hydration. In this research, UHPC hardened paste specimens were prepared with nano-SiO2 dosages of 0 %, 0.5 %, 1 %, 1.5 %, and 2 % by mass of cement, and their mechanical properties were evaluated and statistical features were analyzed. The results indicate that incorporating nano-SiO2 enhances both compressive and flexural strength of UHPC, with the optimal improvement observed at a 1 % dosage. Specifically, UHPC with 1 % nano-SiO2 exhibited a 5.1 % increase in compressive strength and a 6.3 % increase in flexural strength compared to control specimens. These findings suggest that a moderate addition of nano-SiO2 can effectively optimize UHPC’s mechanical performance, offering a promising approach for high-strength, durable concrete in demanding structural applications

Research on expansive soil characteristics – taking Ankang Tunnel as an example

This paper takes the Ankang Tunnel as an example to conduct research on the mechanical characteristics of swelling and shrinkage deformation of expansive soil, such as the free swelling ratio, unloaded swelling ratio, axial load swelling ratio, and swelling pressure, hoping to provide guidance for the construction of similar expansive rock and soil tunnels. The research shows that: (1) The free swelling ratio of the expansive soil in the Ankang Tunnel is relatively low, at 49.7 %, with weak-medium expansiveness. (2) The unloaded swelling process of the expansive soil can be divided into the rapid swelling stage in the initial swelling stage, the swelling transition stage and the slow swelling stage in the middle swelling stage, and the swelling stable stage in the later swelling stage. (3) With the increase of the water content, the swelling pressure of the soil gradually decreases

Research of the influence of the technological parameters of the steelmaking process on the design and defect formation of large-sized castings for freight cars

The research conducted at the “Foundry and Mechanical Plant” JSC is devoted to the analysis of the influence of the temperature regime of pouring 20GL steel into molds on the formation of defects. It was experimentally established that the optimal range of pouring temperatures allows avoiding such defects as hot cracks and underfills. Data were obtained on the time of filling molds, the distribution of defects and the preservation of the metal structure at different temperatures. It was proven that compliance with the temperature range of 1580-1590 °C guarantees high quality castings. Based on the results of the study, technological parameters were proposed that ensure minimal formation of defects and uniform formation of the grain structure

Data-driven modeling and experimental validation of heat-resistant concrete for industrial furnace lining

The purpose of this study is to extend the service life of liquid-layer furnaces through experimental evaluation of their performance. Instead of using conventional large and small aggregates, this research investigates the use of secondary refractory materials to reduce the cost of the concrete mixture. To address this problem, it was proposed to replace the traditional method of lining the furnace floor with SHB-brand fireclay bricks by a monolithic concrete structure. Considering the operational characteristics of the furnace - high temperatures up to 1000 °C and an aggressive environment producing SO3 gaseous sulfur -sodium-infused liquid glass concrete was selected as the base. Instead of cement, liquid glass with low thermal conductivity, including amorphous-phase materials and glass-layered composite viscous substances, is recommended. A novel aspect of this research is the integration of machine learning techniques with experimental data to predict the thermal performance of concrete under high-temperature conditions. Furthermore, the study introduces the use of secondary refractory materials as a cost-effective aggregate alternative, offering a unique combination of sustainability and performance in industrial furnace applications

Analysis of stress-strain in fully bonded basalt fiber plastic anchors

Based on the field pulling test of BFRP anchor, this study studied the stress-strain distribution of BFRP anchor solids of different lengths, analyzed the spatial and temporal distribution of stress-strain, shear stress distribution, axial force characteristics and shear slip displacement characteristics of the interface between BFRP anchor and slurry, and discussed the working mechanism of BFRP anchor solids of different lengths. The effect of bonding length of BFRP bolt on bonding properties between bolt and grout was quantified. The test results show that: The strain of BFRP bolt increases with the increase of load, and decreases with the increase of buried depth; The axial force increases with the increase of cyclic load and decreases with the increase of anchoring depth; The interfacial shear stress decreases exponentially along the anchoring depth, which can be divided into fast decay and slow decay stages; The bonding strength increases with the increase of bonding length, and the strength increases by 2 % to 27 % for every 0.5 m increase in length. This understanding of shear stress distribution helps in accurately assessing the load - transfer mechanism and the potential failure modes of the anchoring system, which is crucial for improving the design and safety of geotechnical anchoring projects

Dynamic modeling of water level in water transfer tunnels on railroad tunnel forces

This study centers on the impact of water level fluctuations in water transfer tunnels regarding the mechanical response characteristics of railroad tunnels. Via a meticulously designed model test, the variation pattern of tunnel lining strain under diverse water level circumstances is thoroughly examined, furnishing a crucial foundation for the design, construction, and safe operation of tunnel engineering. The outcomes denote that water level alterations remarkably influence the tunnel's mechanical response. Each parameter exhibits disparate trends with the ascending water level, and discrepancies exist in the response features of different cross-sectional locations. The test results are as follows: (1) When the water level in the water transfer tunnel is 1 cm, the compressive strain at the outer elevated arch of section I reaches the maximum, and the compressive strain at the inner left arch foot is also the largest. (2) The tensile strain at the outer right arch waist of section II is the greatest, and the compression at the inner right arch waist is severe; the tensile strain at the outer right arch foot of section II exceeds the compressive strain at the arch top, and the compressive strain at the inner right arch foot is the largest. These findings offer a scientific underpinning for exploring the effect of water level loading on the mechanical response of the tunnel structure within the tunnel section beneath the water transfer tunnel, which is highly significant for enhancing project quality and ensuring operational safety