scholarly journals INJECTION MODEL OF CEMENT MORTAR PENETRATION INTO CRACKED ROCKS BEHIND WALLING

2021 ◽  
pp. 57-69
Author(s):  
Andrii Plugin ◽  
Oleh Kalinin ◽  
Sergii Miroshnichenko ◽  
Alina Zvierieva ◽  
Vasyl Holinei ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Dynamic Viscosity ◽  
Fractured Rock ◽  
Geological Structure ◽  
Technical Condition ◽  
Underground Structures ◽  
Depth Of Penetration ◽  
Technological Factors ◽  
Bridge Plate ◽  
Cement Mortars

The natural and technological factors influencing on the depth of injection cement mortars penetration into the cracked rocks and emptiness under the lining of mountain tunnels have been studied. There are the width of cracks in rocks and groundwater pressure in them, the dynamic viscosity of the solution, which is determined by the content of additives-superplasticizer and watercement ratio W/C, the magnitude and duration of pressure during the projection (crimping). Thesefacts were established after the analytical of literature sources and the analysis of features, design and a technical condition of real tunnel, geological structure of processing rocks under their lining. Based on the fundamental rheological equation - Newton's law in viscous flow models of dependences of depth of penetration on factors mentioned above are developed. Because of research of these models the sizes of technological factors, including dynamic viscosity of the mortar, providing the required penetration of cement mortars were received. To ensure the penetration of the solution to a depth of 10 m in cracks with a width of 10 mm, the dynamic viscosity should not exceed over 0.05 Pa·s, and in cracks of 1 mm – 0.01 Pa·s. To ensure the penetration of the solution to a depth of 2 m in cracks with a width of 1 mm, the dynamic viscosity should be in the range of 0.03–0.1 Pa·s, and in cracks of 0.1 mm – 0.0025–0, 01 Pa·s. Superplasticizers allows reducing the dynamic viscosity ofsolutions to such values and effectively increasing the depth of their penetration into cracks and, as a result increasing the water resistance and load-bearing capacity of the fractured rock. The technology of injecting cement mortars with superplasticizer additives has been improved and developed for: the reconstruction of underground structures and massive artificial structures; the designing of a spherical bearing between galvanized concrete without a bald spot and the exposedmetal beams. The technology is recommended to be used for waterproofing and increasing the bearing capacity of tunnel, piers, bridges, and for the device of a laying layer between а withoutballast reinforced concrete bridge plate and longitudinal beams of metal bridges.

Assessment of the technical condition of underground structures of the largest hydroelectric power station in the North Caucasus, the Chirkeyskaya HPP

2021 ◽  
Vol 18 (3) ◽  
pp. 410-420
Author(s):  
Vladimir N. KAVKAZKY ◽  
◽  
Yana V. MEL’NIK ◽  
Alexey P. LEIKIN ◽  
Andrey V. BENIN ◽  
...  
Keyword(s):  
Large Scale ◽  
Practical Importance ◽  
Hydroelectric Power Plant ◽  
Technical Condition ◽  
Hydroelectric Power Station ◽  
Hydroelectric Power ◽  
Underground Structures ◽  
North Caucasus ◽  
The Caucasus ◽  
The North

Objective: Chirkeyskaya HPP is by far the most powerful hydroelectric power plant in the North Caucasus with the highest arched dam in Russia and the second highest dam in the country after the Sayano-Shushenskaya HPP. This explains why it is called the pearl of the Caucasus. Methods: For the operation and maintenance of this unique structure, a large-scale complex of underground structures for various purposes was built, the technical condition of which must be constantly monitored. To carry out work on the survey of underground structures, the management of the design and survey institute of JSC “Lengidroproekt” decided to attract specialists from the Department of Tunnels and Subways and the Test Center “Strength” of Emperor Alexander I Petersburg State Transport University. The work was successfully carried out at the end of 2015. Results: The safety of underground structures was objectively assessed. Recommendations for the repair and further comprehensive reconstruction of the Chirkeyskaya HPP have been developed. Practical importance: Carry out work on the survey of underground structures of Chirkeyskaya HPP is allowes elaborate of complex measures on safety from Chirkeyskaya HPP.

scholarly journals TECHNICAL CONDITION OF CORRUGATED METAL TRANSPORT STRUCTURES

2021 ◽  
pp. 38-50
Author(s):  
J. J. LUCHKO ◽  
V. V. KOVALCHUK
Keyword(s):  
Bearing Capacity ◽  
Technical Condition ◽  
The Body ◽  
Soil Environment ◽  
Metal Structures ◽  
Advantages And Disadvantages ◽  
Methods Of Calculation ◽  
Analysis And Synthesis ◽  
The Impact ◽  
Corrugated Metal

Purpose. The purpose of the work is to establish the real technical condition of transport structures made of corrugated metal structures on the basis of the analysis of scientific and technical sources.And to analyze the experience of operation of metal corrugated structures in the soil environment and to form and generalize the problems of ensuring the reliability and durability of structures made of metal corrugated structures in the conditions of operation on railways and highways of Ukraine. Methodology. To achieve this goal, a review of scientific and technical sources and regulations of different countries on the technical condition of transport facilities in Ukraine was conducted. In particular, data on the distribution of bridges and pipes made of corrugated metal structures by mode of transport are given. It is shown that the development and implementation of new technologies for the repair of existing defective pipes and small bridges, both on the railways and highways of Ukraine is a very important issue. A thorough analysis of the experience of operation of corrugated metal structures in the soil environment in different countries was conducted. Data on the main inadmissible defects of pipes and the reasons of their development are given. CMS' (corrugated metal structures) corrosion and other defects are given. A number of examples of overpass defects, collapse of bridges and structures with MCS in operation are presented. The qualitative indicators of metal corrugated structures, their advantages and disadvantages are also considered, the problems and the analysis of ensuring the reliability and durability of the structures with CMS in the conditions of operation on the railways and highways of Ukraine are formulated. Findings. An analysis of domestic and foreign scientific and technical sources on the technical condition of transport facilities in Ukraine was conducted. In particular, the experience of operation of corrugated metal structures in different countries of the world is studied and generalized. The analysis and synthesis of problems of ensuring the reliability and durability of buildings with CMS in the conditions of operation on the railways and highways of Ukraine. Originality. As a result of the analysis of the technical condition of transport facilities operated on railways and highways of Ukraine, it was found that about 15 % of transport facilities – small and medium bridges and culverts on Ukrainian railways and about 45 % of transport facilities on Ukrainian roads have unacceptable defects and require immediate repair and replacement. Also, it was established on the basis of research that there are no methods for assessing the load-bearing capacity of transport facilities with CMS in the presence in the body of the embankment of the railway or highway metal corrugated structures with a diameter greater than 6 m. It was determined that standards don't include regulations on design and monitoring of CMS on railway tracks. Practical value. On the basis of these data it was possible to offer directions of theoretical and experimental research and methods of calculation, tests of CMS and diagnostics of a technical condition of transport structures with CMS. In particular, the measurement of the impact of the environment on the bearing capacity of the CMS and the measurement of residual deformations of the corrugated metal pipe on the railway track. Execution of the analysis and synthesis of methods of calculation of transport constructions with CMS will lead to improvement of methods of calculation of CMS.

scholarly journals Analysis of Exploitation Damages of the Frame Scaffolding

2019 ◽  
Vol 284 ◽  
pp. 08008 ◽  
Author(s):  
Aleksander Robak ◽  
Michał Pieńko ◽  
Ewa Błazik-Borowa ◽  
Jarosław Bęc ◽  
Iwona Szer
Keyword(s):  
Bearing Capacity ◽  
Power Plants ◽  
Selection Process ◽  
Numerical Models ◽  
Technical Condition ◽  
Construction Sites ◽  
Size Type ◽  
Investment Size ◽  
Imminent Threat ◽  
Investment Location

The analyzes and classifications presented in the article were based on the research carried out in the years 2016 to 2018 on a group of over one hundred scaffoldings assembled and used on construction sites in different parts of Poland. During scaffolding selection process efforts were made to maintain diversification in terms of parameters such as scaffolding size, investment size, type of investment, location and nature of conducted 5works. This resulted in the research being carried out on scaffoldings used for church renovation in a small town or attached to the facades of classic apartment blocks, as well as on scaffoldings used during construction of skyscrapers or facilities of the largest power plants. This variety allows to formulate general conclusions about the technical condition of used frame scaffoldings. Exploitation damages of the frame scaffolding elements were divided into three groups. The first group includes damages to the main structural components, which reduce the strength of the scaffolding elements and hence the whole structure. The qualitative analysis of these damages was made based on numerical models that take into account the geometry of the damage and based on computational nonlinear static analyzes. The second group focuses on exploitation damages such as the lack of a pin on the guardrail bolt which may cause an imminent threat to people using scaffolding. These are local damages that do not affect the bearing capacity and stability of the whole structure but are very important for safe use. The last group consider damages that reduce only aesthetic values and do not have direct impact on bearing capacity and safety of use. Apart from qualitative analyzes the article will present quantitative analyzes showing how frequently given type of damage occurs.

Analysis of the Bearing Capacity of Adhesive Joint of Honeycomb Cores of Sandwich Structures with the Continuous Adhesive Layer

2020 ◽  
Vol 864 ◽  
pp. 228-240
Author(s):  
Andrii Kondratiev ◽  
Oksana Prontsevych ◽  
Tetyana Nabokina
Keyword(s):  
Bearing Capacity ◽  
Adhesive Joint ◽  
Sandwich Structures ◽  
Adhesive Layer ◽  
Honeycomb Structure ◽  
Bonding Process ◽  
Aluminium Foil ◽  
Honeycomb Core ◽  
Technological Parameters ◽  
Depth Of Penetration

Adhesive sandwich structures with the honeycomb core of the metallic foil, polymeric papers and composites are widely and effectively used in the units of aerospace engineering and in the other industries owing to a number of undeniable advantages, including high specific strength and stiffness. In the process of designing and manufacturing of abovementioned structures, it is necessary to ensure high strength and reliability of the adhesive joint of the bearing skins and honeycomb core at a small area of their contact. The decisive factors influencing the bearing capacity of such joint are the technological parameters of the bonding process. Using the finite element modeling, the paper deals with the bearing capacity of the adhesive joint of bearing skins with the honeycomb core based on the aluminium foil and polymeric paper Nomex at transversal tearing for the key factors of the bonding process. The pattern of the adhesive joint failure (on the adhesive of honeycombs) has been revealed, depending on the depth of penetration of honeycombs ends in the adhesive, physical and mechanical characteristics of honeycombs, modulus of elasticity and tearing strength of the adhesive and thickness of the adhesive layer. Peculiar features of behavior of adhesive joints of the bearing skins with the honeycomb core based on the aluminium foil and polymeric paper Nomex under the load have been established, which should be taken into account in designing and manufacturing of honeycomb structures. The recommendations are given with regard to choosing of parameters of the process of honeycomb structure bonding, which allow providing with the acceptable accuracy the optimal depth of penetration of ends of the honeycomb core faces in the adhesive layer of specified depth.

scholarly journals Geotechnical and ecological foundations of the sustainable life cycle of the long-operated unique underground structures of the water disposal system in difficult ground conditions

2019 ◽  
Vol 265 ◽  
pp. 05002
Author(s):  
Nicolay Perminov
Keyword(s):  
Life Cycle ◽  
Operational Reliability ◽  
Technical Condition ◽  
Simultaneous Increase ◽  
Underground Structures ◽  
Joint Work ◽  
Soil System ◽  
Ground Conditions ◽  
Condition Modeling ◽  
Water Disposal

Intensive development of megacities causes the need for sustainable operation of underground urban infrastructure facilities. In the special protection against man-made impact, long-operated unique underground structures of the water disposal system, which are related to facilities with an increased level of responsibility and danger, are needed. In the report, based on the experience of studying the operation of underground wastewater facilities in conditions of weak soils and intensive external static and dynamic impacts, there are proposed new methods for diagnosing their technical condition, modeling and monitoring of the joint work of the "underground structures aggregate of soil" system are implemented, forecasting and shaping conditions for its sustainable life cycle. Point and linear objects of the water canal of St. Petersburg are developed and implemented at unique (to a depth of 70 m.) geotechnology, providing simultaneous increase of bearing capacity, operational reliability and ecological safety of longoperated underground drainage facilities in difficult ground conditions with increasing man-caused impacts.

scholarly journals ANALYSIS OF MODERN METHODS OF BERTH RECONSTRUCTIONS

2018 ◽  
pp. 140-148
Author(s):  
A.V. Slobodyanik
Keyword(s):  
Comparative Analysis ◽  
Bearing Capacity ◽  
Deep Sea ◽  
Technical Condition ◽  
Reconstruction Methods ◽  
Modern Methods ◽  
Methods Of Reconstruction ◽  
New Facilities

The increase of cargo traffic in Ukrainian ports is constrained due to the lack of deep-sea berths of high bearing capacity. Despite the construction of new facilities, it is necessary to make the most of the existing berthing front. The technical condition of the berthing front, according to the results of the surveys, is in an unsatisfactory state. Many quays need substantial reconstruction in order to increase depths and increase operational loads. In the present work the analysis of modern methods of reconstruction of mooring structures of various designs is carried out. The possibility of their application in various conditions is estimated. A new scheme for reconstruction of berthing facilities is proposed. A comparative analysis of the existing reconstruction methods with the proposed one is made.

scholarly journals Conceptual Approaches to Solving the Issue of Reinforcing the Rock - Cut Structures of Geghard Monastery Complex

2021 ◽  
Vol 1 (2) ◽  
pp. 3-9
Author(s):  
† Artavazd Avetik Arzumanyan ◽  
Avetik Artavazd Arzumanyan ◽  
Hasmik Hamle Qaramyan ◽  
Nelli Gagik Muradyan
Keyword(s):  
Mechanical Characteristics ◽  
Technical Condition ◽  
Laboratory Studies ◽  
Underground Structures ◽  
Rock Samples ◽  
Sandstone Rock ◽  
Comprehensive Development ◽  
Strength And Deformation ◽  
Physical And Mechanical Characteristics

The article presents a visual and instrumental research of the technical condition of the main rock-cut structures and their masonry additions, the documentation of their damages (cracks, crevices, destructions and erosions) and deformations, thorough complete laboratory studies of rock samples and their physical and mechanical characteristics, conceptual approaches to preventive and reinforcing measures necessary for the further safe survival of structures, as well as the comprehensive development and implementation of measures to prevent further damages (elimination of causes) and ensure the long-term existence of structures. Based on the analyses carried out, it is recommended to use a ready-made dry mixture mortar of the “Mapegrout'' brand produced by the Italian company “Mapei” to fill cracks if necessary. It is available in the market of the country and is successfully used in the reconstruction of tunnels and other underground structures. The issues of compatibility of reinforcing materials with sandstone rock are also considered on the basis of some averaged data of the main decisive physical and mechanical characteristics of the strength and deformation of sandstone.

scholarly journals Experimental Research on Bending Bearing Capability of Grouted Double Mortise-Tenon Joint for Prefabricated Metro Station Structure

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Xiuren Yang ◽  
Fang Lin ◽  
Meiqun Huang
Keyword(s):  
Bearing Capacity ◽  
Failure Mode ◽  
Characteristic Curve ◽  
Test Results ◽  
Underground Structures ◽  
Metro Station ◽  
Prototype Test ◽  
Resistance Moment ◽  
Ultimate Failure ◽  
Bearing Characteristic

The grouted mortise-tenon joint, invented as the connection between the large prefabricated elements, is the most important component in the prefabricated underground structures. This paper conducts analysis of load-carrying capacity performance and failure mode with 1 : 1 prototype test in key working direction of different double mortise-tenon joint types for the prefabricated metro station. The resistance moment is developed and used to analyze the bending bearing characteristic curve, and the corresponding test results of each stage of the characteristic curve are described in detail. In addition, the bending bearing performance of different types of double-tenon joints under different load conditions is compared. The test results clarify the ultimate failure mode of double-tenon joint and the variable bearing capacity characteristics of the joint with the increase in axial load and explain the bearing performance of each stage. It is also found the auxiliary pretightening device is helpful to delay the appearance of cracks and improve the bearing capacity, especially when it is set on the tension side. The research results have important application value for the joint design of prefabricated metro station structures.

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