Construction and Geotechnics

The study is concerned with the security measures in case of works carried out on gable roofs. Maintenance and repair works of gable roofs are compulsory when any building is used. Different types of networks (power lines, telecommunications etc.) are located on roofs. Gable roof operations are always associated with a risk of falling down as such roofs have slopes. More than 25 percent of accidents during construction operations are connected to the risk of falling down. The facts of falling from a roof are also included into the statistics of "Communications" and "Power industry". The available regulatory documents on labor protection and layout of roofs contain the requirements to safety but these requirements are too general. Specific safety requirements are to be determined at the stage when an engineering design project of a building (roof) is being prepared. It is explained by the fact that gable roofs have different forms and arrangement of engineering systems, thus each design is individual. But in reality it is difficult to make project decisions with respect to safety measures for such kinds of work. According to the legislation related to labor safety, in case of works at heights people are obliged to use full-body safety harness which ensures safety of their work. But the combination of engineering, economic and organizational problems in case of works on gable roofs does not always result in using full-body safety harness. Therefore there is a great risk of falling which results in a high rate of reportable injuries. As an engineering solution of the above-stated problems, it is offered to arrange anchor points or anchor lines to fix full-body safety harness at the stage of designing and constructing works.

Any modern communication center is equipped with a variety of electronic equipment which constitutes the core of its information system. The conditioning system of such premises is to meet the highest requirements to ensure the reliable operations, to provide an operational continuity of work regardless of the season and to guarantee the constant optimum indoor climate for such premises. Therefore, computer and telecommunication equipment manufacturers establish the acceptable changes of microclimatic parameters of air which provide optimal conditions for the equipment operations. For most equipment, the optimized air temperature and humidity which ensure a reliable control and processing of data are established in a fairly narrow range of values. The paper reveals the problems that might occur when the operations of communication and telecommunications centers do not comply with the optimal parameters. The requirements to climatic control systems have been specified which are determined by the requirements of the electronic equipment itself. To some extent, all the requirements determine the completeness of the supplied ventilation and air conditioning systems. According to the characteristic requirements and purposes of technological premises, there are two types of them. The first type includes facilities, equipment which requires the regulation of temperature and humidity; so air-conditioning systems in these areas must be reliable and suitable for a year-round operation. The second type of technological premises are those where equipment is operated with less restricted requirements to temperature and humidity control. In some cases, to improve the reliability of technological air-conditioning systems, the backup equipment is installed. In such a system it is important to steadily manage the conditioner resources and install an automated switching of the backup equipment, if the main one is out of order. As an example, the paper presents the air conditioning control system using a backup unit and describes their functions. We have thoroughly studied the precise control Uniflair and Montair conditioners which are specially designed for telecommunication systems and are able to provide a precise optimized performance and the highest degree of reliability regardless of the external environment conditions.

The article is concerned with analyzing the dephenolization methods used to purify highly concentrated waste water from industrial enterprises which make it possible to discharge the effluents into a centralized water disposal system. We considered the methods of physical and chemical (adsorption, evaporation, extraction), thermooxidational (liquid-phase oxidation and vapor-phase catalytic oxidation), thermal (evaporation), biochemical and complex methods of wastewater treatment. The conditions of wastewater dephenolization have been studied (different temperature, pH of the medium, pressure), the reagents which are used and the possibility of purification from other substances contained in sewerage. The treatment systems of highly concentrated sewerage from phenols are presented for some methods. The analysis is presented in the form of a comparative table that shows the initial and final concentrations of phenol, the required process equipment, as well as the advantages and disadvantages of each method. As a result of the analysis, we specified the conclusions about the effectiveness of these methods depending on the initial concentrations of phenol in wastewater. It was found that many methods can purify effluents with high phenol concentrations but not all of them can make this wastewater suitable for the centralized water disposal systems. After some methods, a post-treatment of sewerage is necessary. In this case, it is possible the use the biochemical method. On the one hand, the final choice of the method will depend on the technical and economic factors and, on the other hand, on the requirements to the residual concentrations of phenol in wastewater.

A closed analytical solution of the linear elasticity problem on the distribution of stresses and strains in a homogeneous isotropic ground massif is presented with such a displacement of its boundary section when the deflection line can be approximated by a polynomial of the second order. The solution was obtained on the basis of the theory of a complex variable functions, developed by G.V. Kolosov and N.I. Muskhelishvili. The value of the lateral soil pressure coefficient is explicitly included in the formulas that determine the numerical values of stress and strain components; and it is essential when considering the stress-strain state of the base of foundations composed of different types of soils. The pictures of isolines of stress and strain can be obtained in any standard mathematical software. The corresponding figures are given in the paper. It is shown that the particular cases of the solution obtained are the solutions of problems on uniform and linearly changing displacements of a part of the half-plane boundary. At the vertical displacement of the half-plane boundary part, the normal stresses and deformations assume the same values at the half-plane points which are symmetric with respect to the symmetry axis of the general nonlinear displacement; when moving horizontally, the values of normal stresses and strains have opposite signs. Tangential stresses and strains at vertical and horizontal displacements take the values which are opposite to the sign of the normal stresses.

In the article are presented formulation, analytical and numerical solutions of the statement for quantitative estimation of deep foundation settlement with regard to foundation depth based on the integration of Melan`s statement. The elements of stress stain conditions (SSC) are specified according to results of analytical treatment with usage of PC Mathcad as well as results of SSC numerical simulations of finite element method. There is provided the formula to rate degree of approximation to limiting state assessment which is necessary for SSC analysis of deep foundation. The article shows that in this case base load-bearing capacity is higher than with an allowance for equivalent side surcharge while foundation settlement - lower.

The authors conducted a series of experiments to study the normal stresses in the sand mass under rigid punches with various extendable. Mendoza was located at the base to a depth of 2.0 b (width of Foundation) with a step of 0.25 b . The analysis of interaction of closely spaced dies and the analysis of changes in normal stress at various points over the whole range of loading up to the destruction of the base with the loss of stability of stamps and heaving of the soil from under the models. Given graphs of rainfall with increasing load and the analysis of limit load and precipitation of stamps with different extendable.

The results of the analysis of the influence of settlement on the daylight of the cross-sectional shape, depth and transverse dimensions of the underground workings at different numerical values of the lateral pressure coefficient host rock. In the article the peculiarities of changes in the values of the vertical displacements of the ground points located on the symmetry axis of generation, for cross sections of workings in the form of a square, half ellipse, circle and deltoids, depending on their geometric dimensions, depth and the coefficient of lateral pressure of the containing array. Presents graphs of the magnitude of the vertical displacement of ground points lying on the axis of symmetry of workings with a cross section in the form of a square, a circle, a half ellipse and deltoids, as you increase the depth of their laying. The results are compared with the results of other authors. It is established that upon reaching certain values, depth and cross-sectional dimensions of development, the impact of these factors becomes significant and there is the problem of the optimal shape of the cross section of development that provides a minimum amount of precipitation the earth's surface.