Applied Mechanics and Materials Vol. 843

Abstract: This paper covers design diagrams and algorithms for determining the strain state of soil mass in case of its underworking. When tunnels are constructed in restrained urban conditions peculiar to megapolises, there is an acute problem related to the assessment of their influence on the existing above-and underground facilities. The strains of buildings and structures that occur as a result of underground construction work may have an impact on the operation reliability of these facilities. Russian regulatory documents in the area of underground urban construction strictly govern the basic parameters of the subsidence trough, such as maximum vertical subsidence, curvature, inclination, etc., for most of the existing underworked structures. Such facilities include both buildings and structures of various purposes above ground and different types of utilities (roads and railways, pipelines, cable lines, etc.). The method described in the paper offers the use of an integral quantity of "volume loss" when tunneling is performed by tunnel-boring machines. The "volume loss" term shall be understood to mean the distance between tunnel lining and soil mass, which initially occurs due to the difference between rotor diameter and lining outside diameter. There are also a number of other technology factors affecting the increase of this parameter, and their quantitative assessment is given in this paper. The method proposed in this paper makes it possible to promptly assess the impact of tunneling operations on the existing underworked structures with account of basic influencing factors.

Abstract: With the rapid growth of cities it is considered that around 75% of the world’s population will live in cities by 2050. Estimates are that the population moving to cities are approximately 172,800 persons per day [1]. This increased demand on cities has resulted in further technological advancement in terms of infrastructure. Although the rail industry has significantly advanced in terms of driverless capability, open gangway train systems and real time monitoring it is important that our awareness of fire safety advances at the same rate.In the past, tunnel and operational fire strategies considered assisted evacuation for persons with reduced mobility (PRM) by on-board staff members, while allowing able bodied persons the ability to self-evacuate to a point of safety outside the incident tunnel. As we move into a future with further automation and less on-board train staff, it may be time to re-evaluate our current thinking in terms of tunnel evacuation strategies for Persons with Reduced Mobility.The aim of this paper is to open the discussion in terms of fire safety in tunnel systems, in particular provision of walkways and the effect on egress within tunnels. The widths of walkways are key factors in the pace at which passengers can disembark from a train onto a walkway.Although there is an active effort to improve walkway provisions within tunnels, the minimum acceptable width limit is still open for debate. This ultimately comes down to a balance between cost (monetary, environmental) and level of acceptable risk.

Abstract: The basic notion underlying urban underground development is that underground space is a non-renewable resource, therefore planning its use must be done in a sustainable, environmentally-responsible manner with due account taken of economic, functional, social, and legal aspects. This paper addresses issues related to the planning, siting, design, construction, operation and maintenance of underground structures in the city of Moscow. The mechanism of the interaction between an underground structure and the surrounding rock masses is described. It is shown that underground engineering can be significantly enhanced through the use of expert systems. The paper also discusses the need for changes to the legal framework for the use of urban underground space.

Abstract: The main requirements for the sewage lining are waterproofing properties, mechanical strength, corrosion resistance, resistance to hydro-abrasive wear. Currently, neither in the literature nor in the practice of underground urban construction, there is no information about the quantitative parameters of the above requirements. This leads to uncertainty when creating new means of protection of concrete lining from the effects of external factors and aggressive media flowing through the collector tunnels. Currently, it is possible to control the characteristics of concrete (to increase its density and decrease porosity) through the introduction of additives (superplasticizers to reduce the water-cement ratio, microsilica) or coating of concrete surface materials, contributing to colmatation. It helps to increase the water resistance of concrete tunnel lining, its resistance to aggressive influences. However, this is not enough to prevent deterioration of concrete when exposed to aggressive environment. The article proposed the evaluation of the above requirements, which will solve the problem of increasing the durability of lining concrete sewers.

Abstract: In the present paper were reviewed causes of loss of tightness of horizontal joints of tubing column, were calculated parameters of expansion clearance of tubing lining, were summarized remedy ways of emergency situations during joint sealing.

Abstract: Modern buildings erected on bedrock or is to be equipped directly in an array (in particular hydroelectric power stations, underground storage facilities and soon), are technically complex, often unique objects construction. At the same time, the cost of design and construction of such facilities is very high. In this context, particular relevance is the question of stable and safe operation of facilities. Now, generally recognized that the study of the functioning of large technical systems (such as the base - structure) with a randomly varying characteristics most adequately carried out was done by different types of complex modeling, particularly mathematical, simulation, and in some cases - physical modeling [3]. However, before moving to a system of «building/foundation» is necessary to examine the massif in situ. Modern software systems (such as Plaxis, ZSoil, Comsol, Abaqus, and soon) have are significant opportunities that allow to make calculations with high accuracy. In particular, implemented a specialized model of soils, such as models of Hoek-Brown, Jointed Rock and others [5]. They allow you to get a more objective picture of the state stress of the array according to the degree of fracturing and anisotropy properties. They allow you to get a more objective picture of the state stress of the array according to the degree of fracturing and anisotropy properties. In addition, is possible a reflection of the detailed features of the geological structure in the 3D calculation that gives an idea of the influence of the field to an array of building/foundation. But, it is necessary to understand that the simulation is based on idealization and averaging the physical and mechanical properties of the medium under study. The inevitable errors and inaccuracies in the calculations. As a real rock massif is a complex system, in the work showed of drawing up an analysis of structural models and their implementation using conventional concepts and a more detailed study. The isolation of the structural elements and boundaries in an array of rocky soils should be approached with special attention. This is due, primarily, with the features of the geological structure of the study area: for example, improperly allocate lithological boundaries as in the case of consideration arrays dispersed soils, because rocky soils is a monolithic solid. Select elements should be performed in accordance with the characteristic feature, such as a fracture, blocking and so on. Besides the issue of numerical modeling of rock masses, in the issues of verification data obtained by numerical method. With the increasing complexity of the technical constructions, increasingly there is a need to verify the results of numerical simulations with actual operating voltage value in the array. Since the field of stress research methods is very expensive and labor-intensive, trade-off seems logical to use in the verification of the results of numerical modeling of acoustic emission (AE) [6]. This method may be used in combination of laboratory tests. With this approach, it is possible to achieve significant improvements in the quality of the received information.

Abstract: The environmental effects of civil engineering activities can generally be divided into positive and negative. The construction process itself, however, with a few exceptions (e.g. possible consumption of waste materials) is typically characterised by the negative impacts. In practice, it is often not possible to avoid these negative impacts but only to minimise them. The necessity of protecting vegetation while conducting building activity springs from the effort to maintain all the positive functions of vegetation in the human life environment. A large leaf area, representing up to ten times the tree crown ground plan and its ability to catch dust particles on its surface, makes vegetation an important element in lowering the amount of dust in the air (a decrease of up to 70%).

Abstract: The paper addresses the use of laser ultrasonic structuroscopy to study how weathering affects the internal structure of rocks used for facing buildings. For 1,250 hours rock samples were subjected to 150 cycles of freezing (at-20°C) and thawing in water (at +20°C) to determine their frost resistance. Also, moistened every 30 minutes, rock samples were exposed to thermal and ultraviolet radiation for 480 hours to determine their weather resistance. The frequency-dependent phase velocity and attenuation coefficient of longitudinal ultrasonic pulses in the samples were measured. It is found that the rock samples are most seriously damaged when exposed to sharp changes in temperature. As a result of freeze-thaw processes, the velocity of elastic waves decreases by 10% on average, and the attenuation coefficient increases by a factor of 1.5 in the range of 300kHz-500kHz and more than 3 times in the range of 1.0MHz-1.5MHz. The coefficient of the relative power of “structural” noise (K parameter) is introduced to characterize the degree of degradation of rock samples. The parameter K is defined as the ratio of the power of noise component in the spectrum of scattered waves to the power of reference signal. It is shown that the parameter K increases almost by a factor of 10 as a result of various weathering processes.

Abstract: Nowadays, large-span underground structures can only be built at shallow depths or in hard rock since their structural strength is not great enough to bear the overburden pressure of thick overlying soil material. To build large-span structures at greater depths or in a wider range of geotechnical conditions, new technical and technological solutions must be developed. The paper discusses the possibility of using stay cable systems to enhance the load-bearing capacity and service performance of large-span underground structures. To assess the applicability of such stay cable systems for large-span underground construction, a numerical model has been developed and validated. The paper presents the results of the modeling of underground structures (20m to 50m wide) under different pressures and examines how the stress-strain behavior of the load-bearing structural elements depends on the span of the structures, the arrangement and height of pylons, and the number and arrangement of stay cables. It is shown that the use of stay cable systems can significantly improve the load-carrying capacity and performance of both individual structural elements of a large-span underground structure and the structure as a whole. The paper also discusses the possibility of using composite materials for the stay cable systems.