scholarly journals COMPARATIVE ANALYSIS OF NATM CONSTRUCTION TECHNOLOGIES OF DNIPRO METRO ESCALATOR TUNNEL

2021 ◽  
pp. 86-91
Author(s):  
O. L. TIUTKIN ◽  
V. P. KUPRII ◽  
S. I. BIELIKOVA
Keyword(s):  
Comparative Analysis ◽  
Reinforced Soil ◽  
Multilayer System ◽  
Weak Soil ◽  
Additional Element ◽  
Advantages And Disadvantages ◽  
Ground Freezing ◽  
Effective Technology ◽  
Artificial Ground Freezing ◽  
Increased Strength

Purpose. On the basis of the comparative analysis to carry out a substantiation of the most expedient and rational way of strengthening of a weak massif during a construction of Dnipro metro escalator tunnels by NATM. Methodology. To achieve this goal, an analysis of construction technologies in weak soils was conducted. The most used technologies are Forepoling Umbrella System (FUS), artificial ground freezing and chemical cementation. The peculiarities of carrying out each of the technologies for the conditions of inclined production were analyzed. It is determined how each of the technologies is applied to escalator tunnels and implements the strengthening of weak soil. Findings. The advantages and disadvantages of three technologies for fixing weak soil around the escalator tunnel are identified. Based on comparative analysis, it was found that the only technology that provides increased strength parameters of loamy soils, characteristic for the upper part of the escalator tunnel of the Dnipro metro, is the technology of chemical strengthening (cementation). In some cases, if necessary, short sections of sloping course, characterized by particularly weak soil, can be supported by several pipes, without creating a continuous leading mount. The results of the analysis are the basis for further substantiation of cementation, which creates a multilayer system "reinforced soil massif – temporary fastening – permanent lining". Originality. Based on the results of comparative analysis of three technologies for escalator tunnel construction by NATM, it is proved that the use of cementation not only increases the strength of the soil during drilling, but also further in operation serves as an additional element of the multilayer system "reinforced soil massif – temporary fastening – permanent lining". Practical value. In the course of research, the substantiation of cementation as the most rational and effective technology of strengthening of the surrounding weak massif at construction of the Dnipro metro was carried out.

scholarly journals Low-temperature ground freezing methods for underground construction in urban areas

2019 ◽  
Vol 265 ◽  
pp. 04020
Author(s):  
Petr Nikolaev ◽  
Mikhail Shuplik
Keyword(s):  
Carbon Dioxide ◽  
Urban Areas ◽  
Construction Projects ◽  
Ground Improvement ◽  
Solid Carbon ◽  
Solid Carbon Dioxide ◽  
Advantages And Disadvantages ◽  
Ground Freezing ◽  
Artificial Ground Freezing ◽  
Freezing Liquid

Artificial ground freezing (AGF) is a commonly used ground improvement technique. It can be applied in diverse construction projects in dense populated urban areas where other methods are inapplicable. In this article are discussed several methods of ground freezing, such as: “brine” freezing, liquid nitrogen freezing, solid carbon dioxide freezing. Their advantages and disadvantages are indicated. For solid carbon dioxide freezing, several approaches are presented. One of them is a brine “aftercooling” freezing method. They can significantly increase efficiency of ground freezing and reduce its cost.

scholarly journals COMPARATIVE ANALYSIS OF TECHNOLOGIES OF MICROPILES ARRANGEMENT DURING STRENGTHENING OF WEAK SOIL BASES

2021 ◽  
pp. 69-77
Author(s):  
V. D. PETRENKO ◽  
V. S. ANDRIEIEV ◽  
V. V. KHARCHENKO
Keyword(s):  
Comparative Analysis ◽  
Modulus Of Elasticity ◽  
Deformation Characteristic ◽  
Element Model ◽  
Technological Parameters ◽  
Weak Soil ◽  
Advantages And Disadvantages ◽  
Soil Cement ◽  
Jet Grouting ◽  
Vertical Displacements

Purpose. Perform a comparative analysis of drill and injection (jet-grouting) and drill and mixing technologies of micropiles arrangement of weak soil bases with the identification of technological features that significantly effect on the design and calculation of weak soil bases strengthening. Methodology. To solve this problem, was conducted of the detailed analysis of the most effective methods of micropiles arrangement during the strengthening of weak soil bases (physical immersion, bored and packing of concrete, drill and injection of ground, drill and mixing soils and application of special effects). Peculiarities of technological parameters of jet-grouting and drill and mixing technologies are considered in detail. The advantages and disadvantages of each of the technologies are revealed. It is proved that the drill and mixing technology has a greater degree of prediction of the stress-strain state change of the inhomogeneous base. To determine the influence of deformation characteristics, a spatial finite-element model based on a flat prototype was created, which was built using automatic triangulation of the professional calculation complex SCAD. Findings. A significant reduction of the deformed state at an almost constant stress state is obtained. When the deformation characteristic increases by 3 times (the ratio of the modulus of elasticity of the soil cement pile and the weak soil), the vertical displacements of the foundation decrease by 1.23 times. Originality. It consists in obtaining the dependence of the change of vertical displacements and stresses on the modulus of elasticity of the soil cement micropile, created on the basis of drill and mixing technology. Practical value. It consists in the obtained results of comparative analysis of substantiation of micropile installation drill and mixing technology during strengthening of weak soil bases with definition of technological features and choice of drill and mixing as the most effective variant from the point of view of technology realization.

Agrarian receipts as a tool for the structural transformation of financial and credit relations in the agrarian business of the region

2019 ◽  
pp. 40-53
Author(s):  
Yuliia Nehoda
Keyword(s):  
Comparative Analysis ◽  
Retrospective Analysis ◽  
Structural Transformation ◽  
Pilot Project ◽  
Bank Lending ◽  
Economic Benefits ◽  
Advantages And Disadvantages ◽  
New Instrument ◽  
Agricultural Business ◽  
Business Entities

The subject of the research – is a set of organizational-economic relations arising in the process of structural transformation of financial and credit relations in the agricultural business. The purpose of the article is a retrospective analysis of structural transformations of financial and credit relations in the agricultural business, evaluation of the effectiveness and feasibility of the introduction of agricultural receipts as a new instrument of lending to the agricultural business of the regions. Methodology of work – system-structural and comparative analyzes (to determine the effectiveness of the crediting mechanism according to the agricultural receipts of the farmers of the region); monographic (when studying the problems of the functioning of the mechanism of lending to agrarians by agrarian receipts) economic analysis (when carrying out a comparative analysis of the mechanism of classical bank lending to the agrarian business and the mechanism of lending to agrarians according to agrarian receipts); modeling and forecasting (when determining ways to overcome the existing deficiencies in the mechanism of lending to agrarian business entities of the region according to agrarian receipts). The results of the work – a retrospective analysis of the structural transformation of financial and credit relations in the agricultural business was carried out. The mechanism of crediting agrarians according to agrarian receipts and the scale of its distribution in the agrarian business of the region are considered. A comparative analysis of the mechanism of classical bank lending to the agrarian business and the mechanism of lending to agrarians according to agrarian receipts was carried out. In the framework of the pilot project “Agrarian receipts in Ukraine” of the international financial corporation (IFC) in partnership with the Swiss Confederation in Ukraine, the example of the Poltava region defined the effectiveness of the crediting mechanism according to the agrarian receipts of the agrarians of the region. The advantages and disadvantages of the mechanism of crediting the subjects of the agrarian business on agrarian receipts are noted. The ways to overcome the existing shortcomings of the mechanism of crediting the subjects of the agrarian business of the region according to agricultural receipts are determined. Conclusions – according to the results of the conducted research, the effectiveness of the mechanism of lending to the agricultural business of the regions according to agricultural receipts was proved, its advantages and disadvantages were noted, and attention was also focused. Proposed in Art. 7 of Law No. 5479-VI clearly delineate cases and restrictions on the debtor’s reimbursement of expenses incurred by the lender with the acquisition of the right to grow and harvest the pledged crop of agricultural products, which will ensure the principle of equality of parties on economic benefits and distribution of credit risks according to agricultural receipts.

Research of methods of protecting organizations from inimical mergers and acquisitions

2020 ◽  
pp. 29-45
Author(s):  
O.A. Naydis ◽  
I.O. Naydis
Keyword(s):  
Comparative Analysis ◽  
Mergers And Acquisitions ◽  
Positive Effects ◽  
Advantages And Disadvantages ◽  
Preventive Methods

The article considers the types, forms, mechanisms and classification of mergers and acquisitions, identifies their positive effects, and studies the tactics of acquisitions. The analysis of anti-capture measures: active and preventive methods of protection against hostile mergers and acquisitions. A comparative analysis of anti-capture measures with acquisitions tactics was carried out, the advantages and disadvantages of their application were identified.

ON COMPARATIVE ANALYSIS OF PERFORMANCE OPTIMIZATION METHODS OF MULTI-PUMP UNITS

2020 ◽  
pp. 23-28
Author(s):  
A.I. Glushchenko ◽  
M.Yu. Serov
Keyword(s):  
Energy Efficiency ◽  
Control System ◽  
Comparative Analysis ◽  
Performance Optimization ◽  
Optimization Methods ◽  
Online Optimization ◽  
New Approach ◽  
Advantages And Disadvantages ◽  
Analysis Of Performance

В статье рассматривается вопрос совершенствования системы управления параллельно-работающими насосными агрегатами с целью повышения энергоэффективности их работы. Проведено сравнение и выявление недостатков существующих методов решения рассматриваемой проблемы. Предложена идея нового подхода на базе онлайн оптимизации. The problem under consideration is improvement of the energy efficiency of a control system of parallel-running pump units. Known methods used to solve this problem are considered. Their advantages and disadvantages are shown. Finally, the idea of a new approach, which is based on online optimization, is proposed.

Effect of Freeze Pipe Eccentricity in Artificial Ground Freezing Applications

2020 ◽  
Author(s):  
Ahmad F. Zueter ◽  
Minghan Xu ◽  
Mahmoud A. Alzoubi ◽  
Agus P. Sasmito
Keyword(s):  
Energy Consumption ◽  
Radiation Heat Transfer ◽  
Conservation Equation ◽  
Underground Mines ◽  
Phase Front ◽  
Two Phase ◽  
Ground Freezing ◽  
Deep Underground ◽  
Artificial Ground Freezing ◽  
Conjugate Model

Abstract Building concentric tubes is one of biggest practical challenges in the construction of freeze-pipes of artificial ground freezing (AGF) applications for deep underground mines. In this study, the influence of tubes eccentricity on phase-front expansion (i.e., expansion of the frozen body) and energy consumption of AGF systems is analyzed. A 1+1D semi-conjugate model that solves two-phase transient energy conservation equation is derived. The model is firstly validated against experimental data and then verified with a fully-conjugate model from the literature. After that, the model is extended to a field scale of typical deep underground mines to study freeze-pipe eccentricity. The results show that an eccentric freeze pipe can reduce the phase-front expansion by around 25%, as compared with a concentric one. Also, the geometrical profile of the phase-front is significantly influenced by the freeze-pipe eccentricity. Furthermore, in the passive zone, where AGF coolants are isolated from the ground to reduce energy consumption, freeze pipe eccentricity can increase the coolant heat gain by 10%. This percentage can increase up to 200% if radiation heat transfer is minimized.

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