When making welded joints, it is not always possible to press tightly elements to be joined before surfacing the weld. In normative documents on welded joints, the allowable gap between the elements to be connected can reach 3 mm  when welding with a covered electrode and 2 mm when welding in shielded gases. At the same time the presence of a gap is not taken into account in the standards for calculation of welded joints. Experimental studies have been carried out to determine effect of the gap on the bearing capacity of the weld. Specimens have been made with welded joints of two types: for work in shear and pull-out. For the purpose of comparison, half of the specimens have been made without gaps, and the other half with gaps between the elements to be joined. The specimens have been made at the Minsk plant of technological metal structures, and their tests have been carried out in a research laboratory of the Belarusian National Technical University. Based on the results of the experiments, it has been concluded that the gaps between the elements to be joined significantly reduce the bearing  capacity of  the welded joints.  In addition,  inspection of  fracture surfaces  have  shown that, in the presence of a gap, the  cut  surfaces of  the weld  pass along the  fusion boundary  of  the base and deposited metals.  It has  been  experimenttally established that the existing gap leads to a slight increase in the penetration depth. However, the latter factor does not compensate for the decrease in the bearing capacity of the welded joint due to the presence of a gap between the elements to be joined.

Using the example of vertical displacements, it is shown that by combining a solution to the problem of determining vertical displacements from the action of four identical concentrated forces symmetrically applied to an elastic half-space and two identical concentrated forces symmetrically applied to an elastic quarter-space, one can obtain a solution about the action of one force on 1/8 of the elastic space with free edges. To find vertical displacements in an elastic half-space, the  Boussinesq  solution  is  used,  and  vertical  displacements in an  elastic  quarter-space – an integral equation obtained by Ya. S. Uflyand to determine vertical displacements in the face of a homogeneous elastic isotropic quarter-space, for which a deformation modulus and Poisson’s ratio are constant. However, an integral equation of Ya. S. Uflyand is very inconvenient for practical use, therefore, in the paper, an approximate expression written in terms of elementary functions is proposed to find vertical displacements in the face of an elastic quarter-space from the action of a concentrated force. To obtain the latter, a special approximation method is used. The desired solution is also expressed in terms of elementary functions. In this case, an accurate calculation is obtained for an incompressible material with Poisson’s ratio 1/8 of the space n = 0.5. Since the solution is obtained in the case of a concentrated force acting on 1/8 of the elastic space, it is easy to find an expression for determining the vertical displacements of the edge of 1/8 of the elastic space from the action of any distributed load by integrating over the area of action of this load from the influence function, which is taken as required decision. Recommendations for improving the accuracy of calculations are offered. The described approach can also be used to determine the stress-strain of 1/8 of the space with both hingedly supported and free edges.

Today, there is an acute issue of ensuring the safe operation of buildings and structures located in the immediate vicinity of new construction. The process of performing works on the installation of load-bearing structures and their further operation can have a negative impact on already existing facilities. In this regard, the task of developing innovative methods and tools to ensure the safe operation of such structures as subway running tunnels is very urgent. To solve it, a reliable forecast of additional deformation and appointment of a complex of protective measures are required.  In addition, much attention should be paid to the numerical modeling of the system “surface structures – protective measures – underground structures”. As an example of assessing the impact of new construction, namely, the erection of surface structures over existing underground  ones, one  can  cite  the  construction  of  a transport  interchange  at  the  intersection  of  Nezavisimosty  Avenue with Filimonov Street. As protective measures, a protective screen on bored piles has been used here, which made it possible to minimize significantly dynamic and static effects on the lining of tunnels and other underground structures of the subway. Effectiveness of protection application is confirmed by the result of monitoring the stress-strain state of running tunnel structures at all stages of traffic  intersection construction. Protective measures and continuous monitoring of the stress-strain state in structures help to avoid accidents during construction and further operation.

 

Erosion is divided into two stages in accordance with the accepted design scheme for erosion of a soil dam during overflow. The paper deals with the first stage, when the downstream thrust prism is washed out. The key factor in calculating erosion deformations is the choice of the solid flow rate formula. Studies show that the mechanism of formation and transportation of solid runoff during erosion of dam models from sandy oils is very similar to that previously described by many authors for the condition of river channel erosion. The peculiarity of the process is that the erosion occurs at high speeds. Therefore, solid runoff almost immediately goes into a suspended state. To select the required formula, experiments have been carried out on models of dams made of sandy soils having various granulometric composition. It has been established that at high velocities under the considered conditions, the value of the solid waste flow rate depends solely on hydraulic characteristics of the flow. The influence of physical and mechanical properties of the eroded soil on the value of the flow rate of solid runoff is insignificant, and they may not be taken into account. Calculations have been carried out using formulas known from river hydraulics, which show that none of them gives sufficient convergence with experimental data. Based on the analysis of a large number of experimental data, a formula for the discharge of solid runoff for erosion conditions of dam models during overflow has been obtained in the paper. This has taken into account the fact that the dam erosion by the overflow has a high degree of stochasticity and is difficult to describe theoretically. This is especially evident in conditions of spatial erosion, when, simultaneously with the classical erosion of the bottom, the sides of the eroded hole periodically collapse, which is difficult to take into account in the calculations.

The paper provides a brief review of the literature on the theory and methods of calculating hinged-connected or articulated structures on an elastic base. The author refers to the works of B. G. Korenev, G. Ya. Popov, I. A. Simvulidi, R. V. Serebryany, A. G. Yuriev, in which, using various approaches, studies have been carried out to calculate hinged-connected beams and slabs on an elastic base. From the analysis of  scientific literature on the topic under consideration, it can be concluded that there is no general approach to solving this problem, which is valid for any hinged-connected beams and plates lying on any model of an elastic base under the action of an arbitrary external load.  In addition, a similar problem for this type of engineering calculations is observed in the normative documents. In the Republic of Belarus, a number of industry documents have been used to calculate pavement bearing elements for various highways and track transverse structures, in which road pavements with a load-bearing element and the connection of elements between themselves (hinged or rigid) are considered in an incoherent formulation. The paper proposes a universal approach for calculating hinged-connected beams on an elastic foundation, based on the mixed method of structural mechanics, taking into account the Zhemochkin ratios for functions of the elastic medium effects. The following hypotheses and assumptions are taken into account: only normal stresses act on  the  contact  of  the  beam  with the base, hypotheses  of  the bending  theory are valid  for beams,  hinges  between  the beams are cylindrical, and the distribution of contact stresses along the width of the beams is uniform. As a result of the proposed calculation, the stress-strain state of a system of hinged-connected beams on an elastic foundation has been investigated, namely: distribution of contact stresses under beams, internal forces in the beams and hinged joints, as well as settlements of the elastic foundation under them. The numerical implementation of this approach has been performed using the mathematical package Mathematica 10.4. Examples of calculation are given for different versions of hinged-connected beams and an elastic base: for three hinged-connected beams based on Winkler and seven – on an elastic half-space.

Reinforcement of columns (piers) is usually accomplished by increasing  cross-section through building-up, injecting reinforcing solutions and external reinforcement. The most and progressive method for strengthening is currently external reinforcement, its essence is to glue high-strength sheets, plates or strips (lamellas) onto structure surface with the help of special adhesives. Scientists pay special attention to theoretical and experimental studies of design solutions for external reinforcement of vertical load-bearing  structures. Unfortunately,   the results  of  such  studies, for example, influence of technology for execution of works on strengthening efficiency are virtually absent. Therefore,  the objective of this paper is to carry out experiments with the purpose to study influence of technological factors on efficiency in strengthening of reinforced concrete structures, which absorb compressive forces. The experimental studies have been made in six series that changed the technology of executed works while using various technological factors. Among the main factors are the following: presence/absence of acute angles; preparation of a base (surface coating); method for gluing reinforcing materials to a structure. A criterion for evaluation of  technology efficiency  has been breaking strength for axial  compression  of  reinforced  samples. Analysis on the results of experimental studies has shown that the highest load-bearing  capacity  is achieved while using samples of columns with rounded edges, provided that an adhesive is applied to sample base and carbon fiber (40.6 tons). The compressive strength of such samples is by 82.2 % higher than the strength of control samples. The strength of reinforced specimens with non-rounded edges has appeared to be the lowest one, namely 34.0 tons. Strengthening of the samples with fiber impregnated with an adhesive has increased the indicator by 74.3 % compared to the control samples. The compressive strength of samples reinforced with carbon fiber adhered to the adhesive which is preliminary spread on the basis  is equal to 38.6 tons, which is by 73.4 % higher than the strength of the control samples.

Determination of  strategies for the formation of satellite cities of Minsk is the basis for the development of a polycentric model of the metropolitan agglomeration. On the basis of the comparative analysis of design solutions for master plans, a concept for improving the planning structure and functional organization of satellite cities has been proposed in the paper. The concept is to adapt their planning structure to one of the promising economic profiles (industrial, scientific and industrial, agrarian and industrial, tourism and recreation). In accordance with the concept, there are four main types of the planning structure of satellite cities that correlate with their city-forming specifics: an urbanized planning structure (type У) – an industrial city, an urbanized-natural structure (type УП) – a scientific-industrial city, a natural-urbanized structure (type ПУ) – agricultural  and  industrial  city and a natural  structure (type П) – tourist and recreational  city.  The selected period (20–30 years). While developing master plans, it is necessary to distinguish two main directions of transformation: transformation and development. The implementation of the first direction is provided by two strategies – fragmentation and defragmentation as well as four varieties of each strategy. Spatial development strategies are consolidation, vector growth, sector growth, radial growth. Particular attention is paid to the analysis of possible options for the placement of functional zones, depending on the distance of the city from the core city. Taking into account the identified strategies for spatial development and analysis of the location of satellite cities in the Minsk agglomeration, twelve planning models have been developed that can be used to create urban planning projects to improve the functional planning organization of settlements in the Minsk agglomeration.

All known forecasting methods cannot do without the help of maps when it comes to natural phenomena and processes. Geographic forecasting can be considered as predicting geographic phenomena or processes that cannot  be explored. Identity of the methodology for forecasting the dynamics of phenomena in time and their propagation in space makes it possible to transfer the patterns that are true for time sequences to spatial series. In contrast to specialized forecasting methods developed by individual sciences, cartography provides a researcher with a general forecasting method called cartographic extrapolation. In this case the extrapolation is understood as the spread of patterns obtained in the course of cartographic analysis of  a  phenomenon  or  a  process to an unexplored part of  this  phenomenon or process to another territory, for the future. The foregoing is considered on the example of a map of Modern vertical movements of the Earth’s crust in the Republic of Belarus which is compiled according to geophysical data and repeated leveling. Predictive patterns and expectations are highlighted while applying the method of cartographic extrapolation on the map. The efficiency of cartographic extrapolation is increased with the complex use of different methods. The interaction of cartographic and remote methods is of particular importance. Joint analysis of maps, aerial and satellite images obtained from different heights and in different ranges helps to predict general global, regional or local patterns. An example of this is geological and geomorphological research. Maps of different contents and the results of interpretation of aerial photographs have been used to predict the neo-tectonic structure of the territory in the zone of junction of the Mikashevich ledge of the crystalline basement and the Turov depression in the Belarusian Polesie.

Metro Service has a huge impact on the development of urban transport infrastructure. The need to increase the efficiency of passenger transportation is caused by the rapid growth in passenger turnover as well as an increase in the distance from the outskirts of the city to the center. In connection with the need to develop a metro service network in Minsk city, which is confirmed by research in the area of passenger traffic in the main areas of the city, the CSM Bessac tunnel boring machine was purchased, which allows significantly to increase the speed of  tunnel driving. The use of a mechanized tunnel boring machine in the traditional concept of the metro network construction, in which driving of tunnels is carried out after construction of stations, does not allow to use a shield with maximum economic efficiency due to the small extent of tunnels.  There is also a need to build assembly-shield chambers and carry out works on disassembling and  assembling  the shield. The application of the new concept developed by Yu. S. Frolov and called “through driving” is actual in the conditions of the use of a mechanized tunnel boring machine. Its essence lies in the continuous driving of tunnels on the line section under construction and the consecutive construction of each station complex as the tunnel boring machine passes through it. To implement the concept of “through driving”, it is relevant to use a semi-closed construction method, in which the floor structure is constructed in an open way, and the other elements are closed. The available solutions of the metro stations constructed while using a semi-closed method of work have been analyzed in the paper. A detailed analysis has been carried out with due account of the adaptation to the construction conditions in Minsk, and the development of structural elements and assemblies of the platform area of the station, which is a two-cantilever vault with a developed transom part, resting on pile-columns of a circular cross section. Forces from the open ring of flexible tunnels lining are supported by a cantilever part of an arch and a bottom plate. The paper considers a design of a metro station, its main elements, their purpose and specificity of work, as well as optimization issues and the results of the design feasibility study.

Nowadays there are a lot of modern technologies in electronic lexicography: speech synthesis technology, cross-referencing between dictionary modules, spell-checking functions, etc. The increasing availability of online information has necessitated intensive research in the area of automatic text summarization within the Natural Language Processing community. Belarusian scientists are also interested in this sphere and new lexicographical approaches for creating a linguistic database are shown in the paper. The authors present English-Belarusian-Russian electronic dictionary TechLex. This is the project of the 2^nd English Department and the Department of Software for Information Systems and Technologies of the Belarusian National Technical University. The linguistic database of the dictionary is compiled not by the traditional method of processing a large number of paper dictionaries and combining the received translations, but by sequential processing of scientific and technical English-language periodicals. While the designing the dictionary the authors have taken into account the analysis of modern electronic multilingual translation dictionaries and created a client-server application in the Java programming language. The client part of the system contains a mobile application for the Android operating system, which has been tested on tablets and smartphones with different screen diagonals. The interface of the TechLex dictionary is designed taking into account the possibility of adding new subject areas and filling them with appropriate lexical material. The main advantage of our dictionary is that it is the first technical multilingual electronic dictionary having a Belarusian version.

 

In the operation schemes of optical electronic devices (OED), such as digital autocollimators, direction finders, Shack-Hartmann sensors, as well as astro-orientation systems, projection measuring systems, geometric calibration schemes for OED, the photo-detector acts not only as a receiving device, but also as a measuring device. The tasks facing the OED photo-detectors. The solution to the problem is the use of several photo-detectors installed on one electronic board. Since OED photo-detectors act, inter alia, as measuring devices, it is necessary to perform their geometric calibration. Geometric calibration involves the measurement of interior orientation parameters used in the processing of OED images. Geometric calibration makes it possible to eliminate errors in mutual exposure of photo-detectors on one electronic board installed in the focal plane, as well as distortions introduced by the OED lens, primarily by distortion. The correctness of the interior orientation parameter determination is influenced by the relative position of the collimator, with the help of which the geometric calibration is performed, and the calibrated OED itself, i. e. the external orientation elements. The task is to separate the interior orientation parameters and the elements of external orientation. This is achieved using the method of mathematical processing of measured data in the forward and inverted positions of the collimator. This method of geometric calibration allows to use it for geometric calibration of OED with a large number of photo-detectors. The paper presents the results of the geometric calibration of the interior orientation parameters when the collimator projects a test object onto three photo-detectors of the OED layout. The factors influencing on the accuracy of the geometric calibration of the interior orientation elements for OED are determined in the paper. The developed method for geometric calibration of the interior orientation parameters for multi-matrix OED provides high measurement accuracy – not more than 0.1''–0.2''.

A man-made catastrophe is considered as an information display of catastrophic development of events in the management system, a peculiar projection of  a man-made catastrophe on the information plane. The paper presents an intellectual model, considers dynamics and ranges of emergency changes in management system parameters, assesses potential risks and  threats  of  catastrophe  emergence.  It  has been  shown  that  at  the  macro-structural  level  for  semantic   description of a catastrophe, it is quite effective to use a tree-like network of scenarios, which displays the conceptual scheme of the subject and problem areas of the catastrophe and is based on judgments of experts, their experience and intuition. This allows probabilistic methods  to  assess  potential  risks  of  a catastrophe using two quantitative indicators: risk (probability) level of  phenomenon occurrence at a certain control point of time and the volume of the expected material loss. It has been suggested that for assessment of possible microstate the fuzzy logic should be applied for each critical object parameter, tolerance limits and functions of affiliation with the fields of fail-safe object functioning should be set by expertise, migration trajectories of relative parameter values should be monitored and terms of their forced return to the working field of regular functioning should be duly provided. Quantitative indicators having imprecise origin have been introduced in the intelligent model of potential risks to assess dynamics of catastrophe threat. One of these indicators is the expert level of catastrophe occurrence during migration of a group of abnormally dangerous parameters of a technical object. The time interval has also been considered which is measured from the current moment to the expected moment of catastrophe occurrence at the preset maximum permissible level of catastrophe threat.