Repair Work Research Articles

Experimental and numerical investigations of an auxetic support structure used for local repair of buried pipelines

Due to the ongoing disasters caused by local damage to underground pipelines in urban areas, a new method has been proposed for local trenchless rehabilitation of pipelines.This method utilizes the auxetic effect of an auxetic pipe structure to create support brackets inside the pipeline for repairing damaged sections, with the aim of reducing overall repair costs and improving efficiency. The main objectives of this study are to demonstrate the feasibility of using auxetic pipes for pipeline repairs and to enhance key parameters of auxetic support pipes. This paper presents a tube with auxetic support - the Surrounding Auxetic Tubular Structure (SATS). Using 3D printing technology, the preparation of SATS specimens was carried out, and the compressive properties of SATS were studied through finite element analysis and quasi-static compression test. The results show that the proposed SATS has a significant negative Poisson's ratio effect during the compression process and exhibits a high structural rebound rate after the load is removed. The size of the structure's boundary is the most influential factor on the auxetic effect. Additionally, the compression displacement of SATS increases with the increase of the elliptical short axis, and decreases with the increase of the elliptical long axis. The compressive load decreases with the increase of the short axis, and increases with the increase of the long axis. This demonstrates the excellent mechanical performance of the proposed auxetic support structure and lays the foundation for the feasibility of local repair work for trenchless rehabilitation.

ANALYSIS OF ACCIDENTS DURING DRILLING WITH FLOATING DEVICES IN THE CASPIAN SEA

At drilling of chinks on areas Gunashli, May 28, Bahar, Neft Dashları, Bulla with density of a chisel solution above (1.9-2,0)·104 N/m3 on depth 2000÷4500 m with balance in system the chink-layer is observed decrease in density of a chisel solution to 1,25÷1,30 g/sm3 with the subsequent open gas fountains. The gas getting in chink by diffusion basically comes to light at washing after lifting and descent of the boring tool. In trenches there are elements of the aerated solution, which density a little above before the circulating. Diffusion is the phenomenon caused by movement of molecules. A principal cause of diffusion of gas is presence of a gradient of concentration. Receipt of gas with diffusion from a layer in a chink will take place until gas molecules goes from a zone with high concentration in zones with low concentration, i.e. in chink. Getting to a chisel solution, diffusion gas, go up together with solutions and passing from zones of high pressures in zones low, extends, therefore its density decreases, that, in turn, conducts to decrease in hydrostatic pressure in a face of a chink and to serious complications. The article examines and analyzes the main causes of complications and accidents that arise during the construction, operation and repair of oil and gas wells, and leading to gas and oil shows, open fountains and fires in the fields of Azerbaijan. The ways in which complications arise during the extraction of hydrocarbons are briefly discussed. The conditions and nature of the occurrence of complications leading to accidents, gas manifestations, open fountains and fires are analyzed. Based on an analysis of the complications that arise during the construction, operation and repair of oil and gas wells, technologies and technical means are presented that make it possible to improve the quality of repair work carried out on oil and gas wells during their construction and operation. Equipment and tools for emergency response are considered. Technologies are proposed for eliminating accidents associated with the breakage and fall of downhole tool equipment onto the bottom, with cleaning the bottom of foreign objects, and with the elimination of stuck pipes. Modern technologies for eliminating gas shows and open fountains complicated by a fire at the mouth of a gushing well are proposed. In a chink it is required to make washing of a chisel solution for prevention of complications with closed preventer with dispersing of a boring column. Keywords: well, manifestation, gas, diffusion, pressure, washing solution.

CURRENT STATE AND DEVELOPMENT PROSPECTS FOR THE RENEWAL OF SEWERAGE NETWORKS IN KHARKIV CITY

Ensuring the reliable operation of sewerage systems is one of the essential tasks of municipal services in Ukrainian cities. As the research shows, in most cases, their construction involved concrete and reinforced concrete, which are prone to destruction under the influence of many factors, particularly microbiological corrosion. The destruction of sewage collectors is often the reason for wastewater leaking into groundwater and soil, resulting in pollution. The article provides statistical data on the ‘Kharkivvodovidvedennia’ Complex of the ME ‘Kharkivvodokanal’ as of 01.01.2024, which operates the city’s external water drainage networks. The article outlines the most common factors that lead to emergencies in sewage networks, such as aging and wear of infrastructure, insufficient maintenance and repair, mechanical damage, pollution and clogging, increased volume of wastewater, planning problems, chemical reactions, biological corrosion, and connection defects. The relationship between these causes may be that corrosion can weaken pipeline materials, making them more vulnerable to mechanical damage and leakage. According to preliminary calculations, it is necessary to relay or rehabilitate (trenchless pipeline laying) at least 22–25 km of city networks annually to ensure the reliability of sewage networks. The article analyses the work cycles performed on the tunnel collectors’ objects and large-diameter collectors over five years. Major repair and reconstruction work that deserves attention includes work on the repair of mine No. 12 of the tunnel collector of the 761 micro-district (mine depth H = 6.75 m, diameter – 5 m); restoration work of the Oleksiivskyi collector Ø 2000 mm near the viewing chamber No. 33 on the street Lopanska; restoration of the collector of the Northern group of factories Ø 900 mm at Danylivskyi Uzviz. As a result, we carried out an analysis of the current state of the sewage network of the city of Kharkiv. The main factor in the wear and tear of sewerage networks is corrosion, which, in turn, can weaken pipeline materials, making them more vulnerable to mechanical damage and leaks. Despite the difficult economic conditions, work on the repair and operation of networks is carried out. Also worthy of special attention for future research is the survey of mines where restoration work took place over the past ten years using modern methods. Keywords: underground construction, sewerage, renewal, repair, reconstruction, bearing capacity, wear, corrosion.

SGuard+: Machine Learning Guided Rule-Based Automated Vulnerability Repair on Smart Contracts

Smart contracts are becoming appealing targets for hackers because of the vast amount of cryptocurrencies under their control. Asset loss due to the exploitation of smart contract codes has increased significantly in recent years. To guarantee that smart contracts are vulnerability-free, there are many works to detect the vulnerabilities of smart contracts, but only a few vulnerability repair works have been proposed. Repairing smart contract vulnerabilities at the source code level is attractive as it is transparent to users, whereas existing repair tools, such as SCRepair and sGuard , suffer from many limitations: (1) ignoring the code of vulnerability prevention; (2) possibly applying the repair to the wrong statements and changing the original business logic of smart contracts; and (3) showing poor performance in terms of time and gas overhead. In this work, we propose machine learning guided rule-based automated vulnerability repair on smart contracts to improve the effectiveness and efficiency of sGuard . To address the limitations mentioned above, we design the features that characterize both the symptoms of vulnerabilities and the methods of vulnerability prevention to learn various vulnerability patterns and reduce false positives. Additionally, a fine-grained localization algorithm is designed by traversing the nodes of the abstract syntax tree, and we refine and extend the repair rules of sGuard to preserve the original business logic of smart contracts and support new vulnerability types. Our tool, named sGuard+ , reduces time overhead based on machine learning models, and reduces gas overhead by fewer code changes and precise patching. In our experiment, we collect a publicly available vulnerability dataset from CVE, SWC, and SmartBugs Curated as a ground truth for evaluations. Overall, sGuard+ repairs more vulnerabilities with less time and gas overhead than state-of-the-art tools. Furthermore, we reproduce about 9,000 historical transactions for regression testing. It is shown that sGuard+ has no impact on the original business logic of smart contracts.

Microstructure and durability of rapid repair mortar with self-emulsifying waterborne epoxy polymer

Due to the low hydration rate of ordinary Portland cement (OPC), it cannot meet the requirements of rapid repair, especially in negative temperature environments. Simultaneously, facing the harsh marine environment, repair materials urgently need high durability. In this paper, a self-emulsifying waterborne epoxy polymer (WEP) suitable for cement systems was combined with sulfoaluminate cement (SAC) to prepare repair materials. The effect of the WEP on the development of microstructure, auto-drying shrinkage and durability was investigated by nuclear magnetic resonance, XRD and SEM methods. Results showed that a continuous interpenetration polymer network (IPN) was intricately woven within the multiphase composites, using the macromolecular network structure formed by —OH groups in WEP and Ca2+ and Al3+ in cement as a bridge. The resistance to chloride migration and water absorption exhibited an increase followed by a decrease. In particular, the resistance to chloride migration was improved by 45 %. Similar trends were observed for the carbonation resistance. Due to the lower porosity and capillary pressure caused by IPN, leading to a decrease in auto-drying shrinkage. Nevertheless, the larger percentage of capillary pores in a mortar with a P/C of 15 % increased the auto-drying shrinkage. The WEP decreased the availability of pores of critical diameter (14 nm) of mortar exposed to water freezing, leading to an increase in the freeze-thaw resistance. The change in P/C hardly affected the resistance to sulfate attack. Under −10°C, at 2 hours, the compressive strength of CSA-based mortar satisfied the load requirements for vehicular operations. This research provides theoretical and practical implications for the repair work of large-scale projects serving in harsh environments.

INCREASING THE WATER RESISTANCE OF THE PLASTER MIXTURE BASED ON GYPSUM-CONTAINING BINDER

The article considers the prospects of using gypsum-based composite materials for repairing damaged walls of limestone-shell rock buildings. Repairing damaged shell rock structures with cement compositions intensifies destructive processes; the use of lime-sand mixtures for repair work on building facades is problematic due to their prolonged hardening. The article substantiates the use of gypsum as the basis of the repair composition. The use of gypsum composites for exterior works requires a significant increase in their water resistance. A plaster mixture based on an ash-cement binder with an addition of lime is proposed; a series of samples with different component contents were made in the planned experiment. Their water resistance was studied using two criteria: the conventional softening coefficient (Кр) and the new one - the water resistance index (Iw); a comparison of these criteria was performed. The significant dependence of these criteria on the measurement conditions, which are not currently standardized, is established. Mathematical models of water resistance characteristics have been built, with the help of which the influence of the content of components on the resistance of the plaster composition to water has been analyzed. To further improve the water resistance of the mixture, a hydrophobizing additive was selected in terms of surface wetting and water absorption. Further research is aimed at optimizing the repair composition using plasticizing, hydrophobizing, and adhesive additives.

Estimation Of Welding Wire Requirements (Electrode) For Installation Of 300 Feet Barge Sideboard Assembly

Installation of the sideboard assemblies on a 300 feet barge requires an estimate of the need for welding wire, besides that an estimate of the need for oxygen and LPG gas is also required for the work of cutting the old sideboard. This is so that the repair work does not experience errors in estimating the amount of consumables used so as not to result in losses for the shipyard company. The objectives obtained during the research were to determine the need for welding wire in the welding process of the 300 feet barge sideboard. The design of this study uses a quantitative approach and there are several variables used including independent variables such as the thickness of the material, the length of the welding, and cutting areas. Dependent variables such as the number of electrodes, oxygen, and LPG gas used. Control variables such as the SMAW welding process using AWS A5.1 E6013 electrodes and cutting using an oxygen and LPG gas cutting blender. The data collection techniques in this study were literature study, observation, and interviews. Based on the calculation, the total need for welding wire for the installation of the 300 feet sideboard assembly is 95.87 kg total oxygen requirement of 241.51 kg and LPG gas of 177.35 kg for cutting the old sideboard.

Improvement of maintenance and repair work on technological wells in the conditions of the “North and South Karamurun” deposit, Kazakhstan

Improvement of maintenance and repair work on technological wells in the conditions of the “North and South Karamurun” deposit, Kazakhstan

ДОСЛІДЖЕННЯ МІЦНОСТІ БЕТОНУ НЕРУЙНІВНИМИ ТА РУЙНІВНИМИ МЕТОДАМИ

Introduction. As a result of the military aggression of the Russian Federation against Ukraine, there is an urgent need to restore damaged and destroyed structures. Depending on the material of the span structure, bridges are divided into reinforced concrete, metal, steel-reinforced concrete, stone and wooden. Reinforced concrete bridges are the most common in Ukraine. Such structures account for almost 94 % of the total number of all bridges. Even if the bridge span is made of metal beams, such structures often have a reinforced concrete overlay slab, which means that reinforced concrete is also an integral load-bearing part of the bridge that requires proper maintenance during operation and, if necessary, repair or restoration work. In order to determine the technical condition of span structures, it is first of all necessary to inspect the structure. Typically, the list of inspection activities includes testing the concrete of structures for compressive strength. Therefore, determining the physical and mechanical characteristics of concrete is an integral part of planning for major repairs, reconstruction or new construction. This paper investigates different methods for determining the concrete strength of bridge elements. The accuracy of the results of different methods in laboratory conditions is analyzed. Problem statement. The use of a particular method has its advantages and disadvantages, which, in turn, can affect the accuracy of the data obtained.

Capacity of Reinforced/Prestressed Concrete Compression Members Strengthened/Repaired Using Ultra-High-Performance Concrete Encasement

Currently, 36% of bridges in the United States need major repair work or replacement and 7% of them are classified as structurally deficient. Most of these bridges can be repaired or strengthened to meet the current load demands and withstand the environmental impacts for the remaining service life. Ultra-high-performance concrete (UHPC) has shown immense potential as a repair and strengthening material thanks to its exceptional characteristics such as high workability, excellent strength and durability, and remarkable energy absorption capacity. This paper presents an analytical approach to predict the capacity of reinforced or prestressed concrete compression members with UHPC encasement (jacket) under combined axial and bending effects. The approach is based on strain compatibility and uses idealized UHPC material models in tension and compression according to the new AASHTO Guide Specifications. The approach uses integration to develop accurate interaction diagrams for any section with complex geometry, which overcomes the approximations of the lamina approach. The paper also provides a comprehensive literature review on UHPC usage in repairing and strengthening concrete bridge columns and piers. A design example of a circular reinforced concrete column is presented to illustrate the proposed approach and to calculate the nominal and design capacities of the composite section. This example has shown that increasing the thickness of the UHPC jacket has a prominent effect on enhancing the axial capacity but only a slight effect on the flexural capacity of compression members.

Риски отказов карьерного экскаватора, связанные с его техническим обслуживанием и ремонтом

High quality and timely maintenance and repair (M&R) of mine electric excavators is crucial to minimizing the risks of failures. The article analyzes the significance of factors the influence the failure rate, including such factors as ergatic, technical, climatic, organizational and technological. The analysis showed the greatest criticality of ergatic, technical and climatic factors, with ergatic being the most important of them. The failure rating of mine excavators by the following systems is presented: working attachments, lifting gear, pressure mechanism, traveling gear, hydraulic system, rotation gear and electrical equipment. The most critical are the working attachments, lifting gear and pressure mechanisms, which make up 72%. The principles to design the concept of conscientious maintenance and repair practice (CM&R) are shown. The Fine-Kinney principle is applied in numerical estimation of the failure risks of mine excavators. Digitalization of target operations for electric crawler-mounted power shovels is proposed and a list of coded types of operations is presented for efficient accounting of the maintenance and repair works. The proposed coding system allows systematization of the MRO processes, providing control and their analysis during the whole operation period.

Glass reinforced plastic (GRP) boats and the impact on coastal environment – Evidence of fibreglass ingestion by marine bivalves from natural populations

Classified as marine debris, man made materials are polluting the world’s oceans. Recently, glass reinforced plastic (GRP) has been shown to degrade and contaminate the coasts. In this pioneering study, fibreglass particles have been detected in the soft parts of oysters and mussels collected from natural populations, in front of an active boatyard. The presence of particulate glass, with concentrations up to 11,220 particles/kg ww in Ostrea edulis and 2740 particles/kg ww in Mytilus edulis, was confirmed by micro Raman spectroscopy. The results showed higher accumulation during the winter months, when boat maintenance activities are peaking and, through repair work, the release of glass fibres in the environment is more likely. Bivalves are considered high risk species due to their sessile nature and extensive filter feeding behaviour. The microparticle inclusion may contribute to adverse impacts on physiological processes and eventually to a decline in the overall health and subsequent death of the animal. The high costs involved in the proper GRP disposal and the lack of recycling facilities worldwide lead to boat abandonement and further contamination of the coasts. For the first time this study presents the extensive fibreglass contamination of natural bivalve populations, in a popular South England sailing harbour, designated a biological and geological site of specific scientific interest (SSRI).

Giant Humanoid Mobility Robot Suit-Method II and Research Challenges

Robot suits can amplify human power, mobility, and height. A giant humanoid mobility robot-Method II was designed using the concept of battle robot suit, AMP in the movie Avatar. The operator aboard Method II is a giant robot that can expand its movement to five times the human muscle strength and 2.5 times the height. The robot suit-type controller can move in synchronization with the movement of both arms and control fingers to collaborate with various tasks. However, there are critical challenges, such as battery weight and duration inefficiency, control complexity, network stability, and difficulties in failure or repair work. This study develops and operates the world’s largest humanoid mobility robot without support fixture up to now, and presents its five future research challenges.

Causes and treatment of bridge cracks

With the large-scale construction and operation of highway bridges in China, the maintenance and repair work of bridges has become increasingly important. The treatment of bridge cracks is a crucial aspect of maintenance and repair. Improper analysis and treatment of cracks in maintenance and repair projects can pose significant safety hazards to bridges. Therefore, it is necessary to conduct a detailed scientific analysis of the cracks in bridges and implement corresponding treatment measures. This paper summarizes common crack diseases in different bridge operation processes, analyzes their causes, and provides relevant references for later maintenance and repair, which has certain reference significance for the maintenance and repair of bridges.

Analisis Faktor Keterlambatan Pelaksanaan perbaikan Jalan rusak Lembar-Pelabuahan Gili Mas Lombok Barat

It is hoped that the repair of the damaged road at Lemi Mas Harbor, West Lombok, Gili Mas will be able to facilitate the transportation of goods and services at Gili Mas Harbor, West Lombok. This road repair work is expected to be completed according to the implementation time stated in the contract. The research location is West Lombok Regency. In this research, a survey was conducted using a questionnaire on the workforce on the project. The delay factors considered in data collection were obtained based on literature studies. Factor analysis and ranking are carried out to see the factors that have the most significant value. The results of the analysis show that the 3 factors with the highest ratings causing delays in the repair project for the damaged Lembar-Pelabuhan Gili Mas Road, West Lombok, are unfinished contract changes (Addendums); poor implementation schedule; and slow design review drawings. Keyword: Road repairs, factor analysis, delays

Personal protective equipment for preventing asbestos exposure in workers.

Personal protective equipment for preventing asbestos exposure in workers.

Automatic detection of sewer defects based on yolov5

As cities modernize, sewer systems continue to expand. However, pipe problems may lead to accidents such as sewage overflow. The traditional sewerage pipe detection technology suffers from low accuracy and inefficiency and mainly relies on manual visual identification, which is prone to subjective errors. In this paper, a new Sewer-Yolov58 model is proposed to solve this problem, which is improved based on the original Yolov5 for real-time detection of sewerage problems to detect pipeline problems in time and is favorable for the subsequent repair work. Through comparison experiments with other models, the results show that the improved Sewer-Yolov58 model has a more efficient and accurate detection effect.

From the experience of the technical examination of hydro-technical tunnels

A comprehensive methodology is proposed and the results of the technical examination of hydraulic tunnels are given. The technique takes into account the influence of water flow, the formation of cavities behind the shell, fixes defects, and reveals the prerequisites for their formation. It consists of visual inspection and non-destructive testing (ultrasonic, electromagnetic, vibro-acoustic). A unified presentation of the examination results is proposed. The optimal basis and operating frequency of the ultrasonic method are substantiated. The gradations of the processes of the formation of cracks in concrete are determined by the frequency of electromagnetic radiation. Examples of tunnel examination are given. Characteristic areas of the objects are identified. For main canals, this is a shell near the entrance and exit portals. Cavities behind the shell can be traced along the entire length of the tunnels. The main defect of the shells of pressure tunnels of power plants is cracks in the reinforced concrete lining. For structures of seasonal drainage, filtration in the bottom is characteristic. The examination results are used to develop projects for repair works. Some methodical regulations can be used for inspecting any underground structures.

LOGISTICS OF MATERIAL FLOWS IN SHIP REPAIR PRODUCTION PROJECTS

A logistics system is a complexly organised, integrated economic system consisting of interconnected links in a single process of managing material and related flows. Project management in logistics systems uses the application of project management methods and models in the process of designing logistics systems and managing changes in them, as well as solving the problems of managing resource flows in logistics systems. The design, creation and management of logistics systems is accompanied by their presentation as an integral set of elements in certain relationships and connections between them. The logistics system should meet the goals of their design and management. The article outlines elements of the mechanism of logistics management of material costs of ship repair production. Efficient use of the company's resources is possible through the systematic development of a system of organisational and technical measures to reduce costs. All cost-cutting measures are closely interrelated and comprehensive, reflecting the relationship of each of them with the entirety of ship repair production elements. The paper substantiates the production features of a ship repair enterprise and analyses the factors that determine the level of costs. It identifies types of ship repair works and stages of preparation of vessels for repair, which makes it possible to plan costs for formation of the production programme. This text presents the production structure of a ship repair enterprise and discusses the peculiarities of product costing. Ship repair companies use planned, indicative, estimated (technical) and reporting costings. This makes it possible to develop a mechanism for managing the costs of ship repair projects and the production process of a ship repair company.

Communication repair in parole oral hearings: Comparing remote and in-person settings

The Parole Board (PB) for England and Wales is responsible for deciding whether prisoners are safe to be released into the community. Although the PB was using remote formats (teleconferencing and videoconferencing) to conduct hearings prior to 2020, the coronavirus (COVID-19) pandemic accelerated the wider application of remote hearings. Such changes in modality can have a significant impact on interactional practices, with participation in remote communication requiring a different set of skills from those normally involved in in-person interaction. We argue that this shift in modality is important because it risks impeding prisoners’ participation in hearings and may limit the legitimacy of a parole hearing decision when examined through the lens of procedural justice theory. In this article, we draw on a dataset of 30 recordings of in-person and remote oral hearings. We analyse sections in which prisoners are questioned by PB panel members to identify whether these interactions can be deemed to be as successful in remotely held hearings as compared with in-person hearings. To assess this, we compare instances of communication problems that occur in the datasets. Applying conversation analysis, we find that instances of repair work from participants are statistically more likely to be present in remote hearings when compared to in-person settings. Our analysis has implications for the operating model being used by the PB and knowledge around participation in remotely held justice contexts.