Abstract. In the paper was indicated the essentiality of large-scale underground space development and high-rise construction of cities in Russia. The basic elements of transport facilities construction effective technology without traffic restriction are developed. Unlike the well-known solutions, it offers the inclusion of an advanced lining in the construction that strengthens the soil mass. The fundamental principles of methods for determining stress in advanced support and monitoring of underground construction, providing the application of pressure sensors, strain sensors and displacement sensors are considered.

Tunnel lining takes significant loads from moving vehicles. The consequences of their impact depend on the design of the railway track and the deformation characteristics of its elements. For their study, a numerical model of a circular tunnel has been developed. As a result of the model calculation, the values of the main vertical stresses in the main tunnel structures were obtained. It is established that with increasing loads from the wheel to the rail from 100 to 200 kN, the voltage on average increases by 50%. The stress distribution is affected by the rigidity of the elastic layer. When it increases, the vertical stresses in the sub-rail support decrease nonlinearly, while in traveling concrete they increase nonlinearly.

Abstract.Assessment of engineering status of railway tunnels with a long working lifespan causes the necessity of definition of the actual stressstrain state of construction design, taking into account the results of inspection of its engineering status. static analysis of lining in this case is performed by finite elements method. In the article the example of such analysis is given. The tunnel is strengthened by the composite tunnel lining consisting of an inner layer of masonry body and a shotcrete outer layer built while rebuilding operation. In response to the inspection considerable variances of the actual lining concrete power of resistance from design value have been revealed, as well as local destructions of a lining and internal voids. It has been estimated that influence of lining concrete resistance power nonhomogeneity leads to decrease in carrying capacity on average by 17.3%. Consideration of inner and outer defects can reduce the carrying capacity by 2-3 times. While that sort of assessment not always allows to reveal dangerous processes in the considered geotechnical system and to realize effective protection measures promptly. In this case it is reasonable to use information modeling on the basis of BIM technologies. In relation to railway tunnels the further enhancement is needed. The following sequence of engineering status assessment of a tunnel while information modeling is proposed: carrying out essential geotechnical and geophysical researches on the route of a tunnel; tunnel structures monitoring system development and deployment, collection and analysis of data; regular control of a tunnel by the railcar with the measuring station; creation of a tunnel digital model, filling it with data, regular updating and checking calculations; development and implementation of essential repair actions.

A detailed theoretical analysis of the processes occurring in foam concrete mixtures in the period between their laying in the mold and the phase transition “from viscous to solid” completion moment. The stages of the formation of inter-pore septa in foam concrete mixtures, depending on the material nature and shape of the solid dispersed particles of raw materials, are sequentially considered. It is shown that their shape affects the mass transfer rate and the density of inter-pore septa during the structure formation. The reasons for the fluctuations in the elasticity of foam films during the predominance period of viscous bonds between the components of the raw material are described. The gas inclusions factors of influence on the dispersion parameters and, as a consequence, the aggregative stability of foam mixtures, are ranked. The positive dispersed reinforcement effect on the mass transfer processes in mixtures and the hardened concrete strength is substantiated.

No abstract