Applied Mechanics and Materials Vol. 843

Abstract: At the present time there are several basic methods of soils characteristics increase during the underground structures construction. Though, frequently the ground freezing method is the most efficient way. Modern Russian investigations show, that in case of small values of frozen grounds (less than 1000 m³) the cost of construction works significantly increase. In such conditions the relevant construction technology is a ground freezing method with the use of solid carbon dioxide, which nowadays is under development in the Mining College in National University of Science and Technology MIS&S.The present article shows the brief review of the main manufacturing schemes of the ground freezing, results of the new theories and experimental investigations, also the analysis of a commercial introduction experience of the ground freezing technology with the using of carbon dioxide.So far, the main difficulties during freezing process design were with the determination of a heat flow to the freezing pipe`s direction. It was not possible to predict the dynamic of ice wall formation and the discharge of carbon dioxide. According to the last investigations, we were succeed in determinating the change dependence of the heat dissipation, depending on the rock massive characteristics, granulometric composition of solid carbon dioxide and also its changing along the freezing pipe. That is why, now we may say that, the developing technology became not just a laboratory workout, but can already has a widespread adoption in praxis

Abstract: The main objective of the research work was to construct a techno-mathematical model of the robotic arm for conducting painting work, which would streamline the speed and quality of work performed with respect to material savings. For research we chose a robotic arm that is commonly used in industrial production, and adapted it for our conditions. The mathematical model is designed to find the optimal trajectory for moving the robotic arm, where the emphasis is placed on minimizing the path length of motion of the robot ́s endpoint, thus reducing overall energy consumption for the building work. First, the optimal mathematical modeling method was chosen, it was selected according to conditions and parameters of the robotic arm. Thanks to the applied method we picked the software that helped to create the algorithm. Subsequently, a computer simulation and calculation of the optimal motion using a combination of virtual circles, sine and cosine theorem, was done. Further, we checked all relevant angles and calculation of the robotic arm rotation in space for each admissible variant. The last step was the selection of the optimal trajectory of the robotic arm in 3D space.

Abstract: ANNOTATIONThis article proposes an approach to the prediction of stress state and assessing the strength of a circular tunnel lining and the surrounding rock mass under construction near the production used by the micro-tunneling technology of pipe ramming. The basis of this method is an analytical solution of the corresponding plane problem of elasticity theory.

Abstract: Water and construction works are in continuous interaction. With reference to water protection the effect of construction sites must be considered from two viewpoints: protection of water quality and protection of water quantity and availability. On the other hand, water and its qualitative and quantitative parameters determine the technologies and materials used on construction sites, making their use even impossible in extreme cases.

Abstract: In the Army of the Czech Republic, the protective structure design is currently regulated by a military standard Žen 2-1/1, mainly for buried structures and against nuclear loads. As the nature of current armed conflicts suggests, it would be more appropriate to design above-ground protective structures exposed to the effects of direct or indirect fire weapons. The paper describes a search for an ideal above-ground structural shape exposed to an airblast. Several shapes were designed and their behavior under a typical airblast loading was tested using ANSYS software. As a result of the analysis, the most suitable shape of a protection structure was designed.

Abstract: In the heart of the processes of formation of physical and mechanical properties of secondary lining of underground structures is the residual water-cement ratio, which indicates the extraction of the mixing water of the concrete mixture under the action of external pressure forces. This article examines the nature of the redistribution of the mixing water in the concrete lining of the tunnels. Under the influence of radial and axial forces from laid concrete mix there is an increase in water-cement ratio in the direction from the sole to the vault head of the tunnel. This leads to deterioration of physical and mechanical properties of the lining in the roof part of the tunnel. When calculating the strength and water resistance of the secondary concrete tunnel lining the characteristics of the concrete type by strength and waterproof, adjusted by the weakest part of the lining – its roof part – should be taken into account. The analysis of influence on the technology of erection of the lining is given.

Abstract: Human activities have a considerable effect upon the development of all components of the natural environment. The activity of construction represents a considerable influence upon the environment, with its significance growing with the rate of urbanisation. The high concentration of people in cities and towns has resulted in this urban environment representing the living community for over 50 percent of the population. Construction based activities not only provide material conditions for an urban population, but also influence its social behaviour. As such, no civil engineering designs are able to ignore the influences or impacts which structures may have on the environment especially dust pollution and erosion of soil that is one of the principal resources of the biosphere. As a limited and irreplaceable natural resource it becomes the limiting factor of the development of society in case of its destruction or degradation. By being the living space of most plants it enables energy transformation in the framework of the ecosystem by way of the autothropic stratum represented by the green vegetation. Organic matter produced on the soil serves in numerous ways, whether directly or indirectly, the needs of man. Also the subsoil water runoff depends on soil properties. The loss of soil transforms the subsoil water runoff into surface water runoff with all negative consequences of such transformation.

Abstract: Investigation of residual stresses in an infrastructure is important due to the reason of safety. One of the most important problems is non-destructive testing of residual stresses particularly in welded constructions. A quite lot of technologies are used to solve this problem. Ultrasonic testing is based on the dependence of the velocity of ultrasonic waves on the stress value within a material under study. This technology is robust, operative and can be used in field conditions. The main problem is to measure the velocity of ultrasonic waves with high precision at a short trace. The proposed technique of the Contact Laser-Ultrasonic Evaluation (CLUE) is used in our work to overcome this difficulty. The variation of the results of the measurement of the ultrasonic wave velocity using CLUE does not exceed 0.05% and provides the threshold of the detection of the residual stress in steel at the level of 2-3 MPa. Basics of CLUE and some experimental cases of the study of the uniaxial stress in compressed and tensioned rail steel specimens are described. The advantages and disadvantages of CLUE for the stress measurement are discussed.

Abstract: The weakening of the rock massive has been determined during boring of freezing tubes. It has been proved that the freezing column is disjoint from the massive by mud solution with strength 0,7-0,8 MPa, which fills out the drill hole Ø250mm. Were established lows of forming of the shear stress regions on the freezing pipe`s circuit. Were suggested adjunctive technological measures such as exhaust solution injection in the annular space, which reducing intensity of blasting loads on freezing pipe.