scholarly journals Theoretical analysis of frozen wall dynamics during transition to ice holding stage

2020 ◽  
Vol 243 ◽  
pp. 319
Author(s):  
Mikhail Semin ◽  
Lev Levin ◽  
Aleksandr Bogomyagkov
Keyword(s):  
Rock Mass ◽  
Pore Water ◽  
Wall Thickness ◽  
Operation Mode ◽  
Emergency Operation ◽  
Freezing Temperature ◽  
Normal Operation ◽  
Emergency Situations ◽  
Frozen Wall ◽  
Potash Mine

Series of calculations for the artificial freezing of the rock mass during construction of mineshafts for the conditions of a potash mine in development was carried out. Numerical solution was obtained through the finite element method using ANSYS software package. Numerical dependencies of frozen wall thickness on time in the ice growing stage and ice holding stage are obtained for two layers of the rock mass with different thermophysical properties. External and internal ice wall boundaries were calculated in two ways: by the actual freezing temperature of pore water and by the temperature of –8 °С, at which laboratory measurements of frozen rocks' strength were carried out. Normal operation mode of the freezing station, as well as the emergency mode, associated with the failure of one of the freezing columns, are considered. Dependence of a decrease in frozen wall thickness in the ice holding stage on the duration of the ice growing stage was studied. It was determined that in emergency operation mode of the freezing system, frozen wall thickness by the –8 °C isotherm can decrease by more than 1.5 m. In this case frozen wall thickness by the isotherm of actual freezing of water almost always maintains positive dynamics. It is shown that when analyzing frozen wall thickness using the isotherm of actual freezing of pore water, it is not possible to assess the danger of emergency situations associated with the failure of freezing columns.

scholarly journals Determination of technological parameters of rock freezing systems based on the condition of maintaining design thickness of ice wall

2021 ◽  
Vol 6 (3) ◽  
pp. 192-202
Author(s):  
M. A. Semin ◽  
A. V. Bogomyagkov ◽  
L. Y. Levin
Keyword(s):  
Theoretical Analysis ◽  
Wall Thickness ◽  
Operation Mode ◽  
Emergency Operation ◽  
Normal Operation ◽  
Thermal Calculation ◽  
Clay Layer ◽  
Technological Parameters ◽  
Under Construction ◽  
Thermotechnical Calculation

Artificial freezing ensures the formation of a temporary ice wall around the shaft under construction, which prevents groundwater penetration into the shaft and increases the strength of rocks around the unsupported walls of the shaft until the permanent support is erected. The purpose of the study is to carry out thermotechnical calculation of ice wall with subsequent theoretical analysis of changing ice wall thickness with shifting to the passive freezing stage. The idea of the study is to determine these technological parameters based on the condition of maintaining the design ice wall thickness at the stage of passive freezing. The methodology and results of thermotechnical calculation of ice wall for the clay layer as applied to the case of the shafts under construction of a potash mine in the Republic of Belarus are presented. The thermal calculation of the ice wall was carried out numerically in the ANSYS software package using the finite element method. The findings of the numerical multiparameter modeling allowed theoretical analysis of ice wall thickness decrease with shifting to the passive freezing stage with higher brine temperature. The decrease in ice wall thickness was studied both during normal operation of the freezing station and at emergency operation mode caused by the failure of one of the freezing columns. Special attention in the analysis was paid to studying the influence of the duration of the active freezing stage and the distance between the columns on the decrease in the ice wall thickness. When analyzing changes in ice wall thickness at different distances between the freezing columns, it was found that the most common column spacing in the range from 1.1 to 1.3 m requires observing restrictions on the duration of active freezing to prevent a critical decrease in ice wall thickness during the passive freezing stage or decreasing the distance between the freezing columns. In this case, preservation of positive dynamics of ice wall thickness growth is ensured. For the clay layer considered in the study and the distance between the columns from 1.1 to 1.3 m, the minimum time of active freezing is also about 4.3 months. As a result of the analysis, the technological parameters of the freezing system (duration of the active freezing stage and the distance between the freezing columns) were determined, at which the ice wall thickness at the passive freezing stage did not become lower than the minimum permissible values calculated based on the strength and creep conditions.

scholarly journals Problems of Development and Implementation of Personal Protection Equipment for Personnel of Radiation and Chemical Hazardous Facilities, Emergency and Rescue Teams and Population

2021 ◽  
pp. 69-72
Author(s):  
V.I. Rubtsov ◽  
◽  
G.A. Novikov ◽  
A.N. Timoshenko ◽  
G.P. Prostakishin ◽  
...  
Keyword(s):  
Personal Protective Equipment ◽  
Energy Use ◽  
Operation Mode ◽  
Normal Operation ◽  
Protective Equipment ◽  
Personal Protection ◽  
Personal Protection Equipment ◽  
Emergency Rescue ◽  
Emergency Situations ◽  
Influence Area

The article presents a brief review of the activities of the laboratory "Personal protection equipment for the personnel of hazardous production facilities" for creation of the regulatory-legal and regulatory-methodological support system for personal protection of the personnel of radiation and chemical hazardous facilities, of regular and non-staff emergency rescue teams of Rosatom State Corporation and of FMBA of Russia as well as of the population living in the influence area of the mentioned facilities. The issues of standardization and certification of personal protective equipment at NPPs and in the field of atomic energy use — both in the normal operation mode of dangerous objects, and in emergency situations of peace and war time are considered. The problems arising in the implementation of innovative personal protective equipment, primarily due to international obligations, are shown.

scholarly journals ANALYSIS OF EMERGENCY OPERATION OF WATER PIPELINES

2021 ◽  
pp. 122-129
Author(s):  
O.G. Dobrovolskaya ◽  
Keyword(s):  
Water Supply ◽  
Operation Mode ◽  
Flow Distribution ◽  
Emergency Operation ◽  
Pressure Control ◽  
Design Stage ◽  
Supply Network ◽  
Flow Management ◽  
Water Supply Network ◽  
Emergency Situations

In this work, the influence of individual sections of the water supply network on the dynamics of nodal heads in emergency operating modes is investigated. During accidents in the network sections, the dynamics of the head changes, the supply of water to the network decreases, areas with insufficient heads are formed. The subject of the analyzed stage of research is the influence of individual sections of the network on the location and size of areas with insufficient head. To determine the influence of individual sections of the network on head dynamics, methods of mathematical modeling of flow distribution in the water supply network, methods of hydraulic calculations of water supply networks were used. The results of studies of formation and change of areas with insufficient head taking into account emergency situations for networks with different structure and configuration are presented. The tasks to be performed by the flow management system at the network design stage are defined. Based on the results of the studies, the water supply conditions were evaluated during the formation of areas of insufficient pressure. Proposed algorithm consists of visualization of network structure, simulation of emergency situations, hydraulic calculations of network in normal and emergency operation modes, determination of actual head in network nodes, clarification of location of control nodes, calculation of required head of pumps in emergency operation mode. The proposed method allows you to determine the priority selection of network sections during its reconstruction and restoration. Modeling and analysis of pressure zones in the network allows you to change the number and location of pressure control units depending on the need. The proposed recommendations on flow management can be implemented in the work of utility dispatch services.

scholarly journals Probabilistic-deterministic approach of controlling the functionality of a technical system in normal and emergency operation modes

2018 ◽  
Vol 226 ◽  
pp. 04008
Author(s):  
Vladimir M. Zababurin ◽  
Marina A. Egorova ◽  
Yuliya A. Polyakova
Keyword(s):  
Open Systems ◽  
System Development ◽  
Emergency Situation ◽  
Emergency Operation ◽  
Technical System ◽  
Emergency Situations ◽  
Recovery Processes ◽  
Current State ◽  
Self Organized Criticality ◽  
Technical Systems

The main disadvantages of the existing methods of managing the current state of technical systems are revealed. A non-standard approach is proposed for managing the functionality of the system in emergency situations. The character of the dynamics of the recovery processes of the technical system is determined as its state approaches the emergency one on the basis of the recommendations of the theory of self-organized criticality (SOC). The physical criteria for assessing the current state of the technical system are revealed. The rationale for using the physical indicator of the functional destabilization of the system is given. The signs of the pre-emergency state of the technical system are considered. A grapho-analytical model for the development of an emergency situation has been developed. The fact of the inevitable increase in the entropy of the system upon its transition to an emergency state is established. Structuring of the system development process in an emergency situation is carried out in three stages. The methodology for estimating the pre-emergency state of complex open systems is presented. The advantages of the proposed approach to managing the state of technical systems in comparison with traditional ones are established.

The Field Measure of Special Strata Freezing Temperature in West Area

2012 ◽  
Vol 170-173 ◽  
pp. 1207-1210
Author(s):  
Jun Hao Chen ◽  
Rui Zhang
Keyword(s):  
Engineering Design ◽  
Freezing Temperature ◽  
Design Requirement ◽  
Shaft Sinking ◽  
Design Requirements ◽  
Security Information ◽  
Frozen Wall ◽  
The Difference ◽  
Circle Tube ◽  
Field Measure

A new round of upsurge of mine well construction were set off in the west area, but there are many problems, this article through the field measure of special strata freezing temperature in Bo-jiang-hai-zi coal mine airshaft, use the freezing shaft sinking security information network visualization platform that developed by Anhui University of Science and Technology, analysis several different strata, obtain the overall temperatre decline rate, and compare the difference between in-site shaft well temperature and the calculation value at different position, and difference is very small, it shows that the platform can good response the actual situation. Through calculation, the frozen wall thickness, average of frozen wall temperature, shaft well temperature are meet the engineering design requirement, so propose that in west area at the freezing method mine well construction, the main purpose is waterproof, and use single circle tube freezing can satisfy engineering design requirements.

scholarly journals PLANNING OF EXPERIMENTAL STUDIES OF THE "FOUNDATION-BASE" SYSTEM IN CASE OF SUDDEN OVERLOADS

2020 ◽  
pp. 5-12
Author(s):  
I. M. Diakov ◽  
M. I. Diakov ◽  
B. Y. Barykin
Keyword(s):  
Experimental Studies ◽  
Normal Operation ◽  
Base System ◽  
System Operation ◽  
Foundation Soil ◽  
Soil System ◽  
Emergency Situations ◽  
Foundation Base ◽  
Sudden Loading ◽  
Experimental And Theoretical Studies

The relevance of experimental and theoretical studies of the work of the foundation-foundation system in sudden burdens is justified. It was established that sudden loads can occur both in emergency situations and in the course of normal operation. The main criterion of sudden loading is the rate of additional or main (operational) loading, which is higher than the rate of stress redistribution in the base. In order to identify the main features of the foundation-foundation system and plan further studies, the results of preliminary experiments of the interaction of foundations with the soil base during sudden loads were analyzed. The accepted method of experimental research is described, the characteristics of the models of foundations and the power system used for testing are given. Some features of "foundation-soil" system operation in case of sudden loading are defined. Based on the conducted experiments, the need for further study of the foundation-foundation system in case of sudden loading was substantiated and the experiments were planned.

RISK MANAGEMENT OF EMERGENCIES OF BUSINESS STRUCTURES IN THE CONTEXT OF GLOBAL INFORMATIZATION

2017 ◽  
Author(s):  
Hamed Rashed Sayed Abdullah Alnuaimi ◽  
Keyword(s):  
Risk Management ◽  
Management System ◽  
Living Conditions ◽  
Normal Operation ◽  
Natural Phenomenon ◽  
Emergency Situations ◽  
Risk Management System ◽  
Business Structures ◽  
The Impact ◽  
Business Structure

Modern processes in a society increasingly began to take on the character of emergencies, namely, the situation in a certain territory, which developed as a result of an accident, a dangerous natural phenomenon, a catastrophe, the spread of a disease, a natural or other disasters that may or did entail human casualties, damage to health people or the environment, significant material losses and disruption of the living conditions of people. At the current time, such a situation is the COVID-19 pandemic, which has already claimed the lives of many people and brought significant economic consequences, including a complete shutdown of the activities of business structures. In this regard, the purpose of the study is to develop a conceptual framework for a risk management system for emergency situations, which can ensure the normal operation of a business structure and prevent its death in the event of an emergency event of any nature. The author analyzed the impact of the COVID-19 pandemic on society and the activities of business structures as one of the latest and most striking examples of emergencies. The analysis revealed that this event could completely destroy the business; therefore, the primary and indispensable criterion for the normal viability of a modern business structure is the ability of top management, based on a strictly scientific basis, to predict, carry out prevention, rationally control and effectively manage risks. Based on the analysis, the author proposed conceptual risk management of emergencies for business structures in the context of global informatization of digitalization. The proposed system is based on the fact that modern processes in society are a symbiosis of two concepts - emergency situations and "black swan", i.e. this is difficult to predict an event that has significant financial and material losses and a violation of the living conditions of an economic entity up to its complete dysfunction. The proposed comprehensive emergency risk management system will allow neutralizing two main and most ambitious consequences: catastrophic losses (financial, labour) and suddenness of the event.

scholarly journals Application of Analytical Solution to Steady-State Temperature Field by Double-Row-Pipe Freezing and Verification with Field Measurement: A Case Study of Connected Aisle

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Zequn Hong ◽  
Xiangdong Hu
Keyword(s):  
Temperature Field ◽  
Steady State ◽  
Analytical Solution ◽  
Wall Thickness ◽  
Field Measurement ◽  
Field Analysis ◽  
Shield Tunnel ◽  
Double Row ◽  
Steady State Temperature ◽  
Frozen Wall

In order to solve the problem of sealing water and bearing capacity of a connected aisle in an underwater shield tunnel, a double-circle horizontal freezing method was adopted for ground reinforcement in the connected aisle of Maliuzhou Tunnel, which is China’s first shield tunnel with superlarge diameter built in a composite stratum. This paper proposed a new double-row-pipe freezing model for the calculation of frozen wall thickness based on analytical solution to steady-state temperature field. Besides, field measurement and transient numerical studies of the active freezing period were also carried out to study the freeze-sealing effect. The results show that frozen wall thickness obtained by analytical solutions agrees well with numerical simulation results, which verifies the applicability of the newly proposed calculation method. Field analysis indicates that soil temperature gradually approaches a stable value which is far below the freezing point, and a reliable water-sealing curtain can be formed around the designed connected aisle. Maximum impact of soil excavation on the frozen wall is about 10°C, and reducing exposure time of excavation surface can effectively alleviate the weakening of frozen wall. To obtain comprehensive analysis for freezing wall thickness, a more reasonable arrangement of temperature-measuring holes is expected in future freezing engineering.

Emergency Control of Vehicle Platoons: Control of Following-Law Vehicles

1976 ◽  
Vol 98 (3) ◽  
pp. 239-244 ◽  
Author(s):  
R. J. Rouse ◽  
L. L. Hoberock
Keyword(s):  
Emergency Operation ◽  
Dynamical Analysis ◽  
Normal Operation ◽  
Target Velocity ◽  
Longitudinal Control ◽  
Emergency Control ◽  
Vehicle System ◽  
Design Speed ◽  
Vehicle Platoons

This work presents a dynamical analysis of platooned following-law vehicles under longitudinal control proposed in [1]. It is shown that controller gains selected for normal operation give inadequate performance in emergency operation. Dangerous spacing in platoons moving at lower than design speed and delayed target velocity update effects are investigated. Stability of the vehicle system in emergency operation is related to controller gains, and simulations for various emergency contingencies are presented.

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