HYDRAULICS. ENGINEERING HYDROLOGY. HYDRAULIC ENGINEERING

Staged construction of a rockfill dam is the way of regulating the reinforced concrete face stress-strain state

Vestnik MGSU 11/2018 Volume 13
  • Podvysotckii Aleksei A. - Mosoblgidroproekt Candidate of Technical Sciences, Head of Hydrotechnical Department, Mosoblgidroproekt, 1 Energetikov st., Dedovsk, 143532, Russian Federation.
  • Sainov Mikhail P. - Moscow State University of Civil Engineering (National Research University) (MGSU) Candidate of Technical Sciences, Associate Professor, Associate Professor of Department of Hydraulics and Hydraulic Engineering, Moscow State University of Civil Engineering (National Research University) (MGSU), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation.
  • Soroka Vladislav B. - SpetsNovostroy engineer, SpetsNovostroy, 20 Communal quarter, Krasnogorsk, 143405, Russian Federation.
  • Dogonov Mark L. - Moscow State University of Civil Engineering (National Research University) (MGSU) graduate student, Moscow State University of Civil Engineering (National Research University) (MGSU), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation.

Pages 1395-1406

Introduction. Presented the approach to studies of the impact of a rockfill dam staged construction on the reinforced concrete face SSS. Experience in construction of reinforced concrete face rockfill dams (CFRD) shows that at perception of hydrostatic pressure the integrity of the seepage-control element may be broken. By the results of mathematical modeling it was revealed that the tensile stresses appearing in the face concrete may exceed concrete design tensile strength. The causes of appearing tensile stresses are bending deformations and the face longitudinal extension. The urgent issue is selection of the way of improving the stress-strain state (SSS) of the face to provide its safe operation as a seepage-control element. Materials and methods. The studies were conducted on the example of a 100 m high dam with the aid of numerical modeling. Two cases were considered: in the first case the dam was constructed in one stage, in the other in two stages. Rockfill is considered as a lineally deformed material, but computations were conducted for a wide range of the soil linear deformation modulus: from 60 to 480 МPа. Steel reinforcement was considered in the face. Results. Longitudinal stresses in a reinforced concrete face were compared for two cases of the dam staged construction. Analysis was fulfilled with determination of the longitudinal force and bending moment appearing in the face. The obtained maximum values of tensile longitudinal stresses in the face were compared for two cases. Conclusion. It was revealed that construction and loading of the dam by stages on the whole is favorable for the face stress-strain state. The second-stage dam weight transfers to the first-stage face the compressive longitudinal force, which permits decreasing tensile stresses in it. Bending moments in the face vary insignificantly and even may increase to some extent by value. Nevertheless, at dam construction and reservoir filling in 2 stages the maximum values of tensile stresses in the face concrete decrease, therefore, such construction sequence contributes to enhancing safety of the dam seepage-control element.

DOI: 10.22227/1997-0935.2018.11.1395-1406

Download

Stress-strain state of fiberglass in conditions of climatic aging

Vestnik MGSU 12/2018 Volume 13
  • Martynov Gleb V. - Peter the Great St. Petersburg Polytechnic University (SPbPU) undergraduate student, Peter the Great St. Petersburg Polytechnic University (SPbPU), 29 Polytechnicheskaya st., St. Petersburg, 195251, Russian Federation.
  • Monastyreva Daria E. - Peter the Great St. Petersburg Polytechnic University (SPbPU) undergraduate student, Peter the Great St. Petersburg Polytechnic University (SPbPU), 29 Polytechnicheskaya st., St. Petersburg, 195251, Russian Federation.
  • Morina Elena A. - Peter the Great St. Petersburg Polytechnic University (SPbPU) undergraduate student, Peter the Great St. Petersburg Polytechnic University (SPbPU), 29 Polytechnicheskaya st., St. Petersburg, 195251, Russian Federation.
  • Makarov Aleksey I. - Peter the Great St. Petersburg Polytechnic University (SPbPU) undergraduate student, Peter the Great St. Petersburg Polytechnic University (SPbPU), 29 Polytechnicheskaya st., St. Petersburg, 195251, Russian Federation.

Pages 1509-1523

Introduction. Were investigated samples of fiberglass with the aim of its effective use in construction in the long term. Fiberglass is considered one of the most versatile and durable materials among polymer composite materials, however, and it is subject to destruction. It is known that one of the main reasons for reducing the specified characteristics and material properties is operational. At the design stage, it is necessary to determine the most reliable and economical materials used and, accordingly, be sufficiently aware of their strength and durability. Thus, in order to avoid the destruction of the material, as well as significantly enhance and prolong its service life, it is necessary to be aware of how exactly the properties of the material change over time. Regarding reinforced concrete, wood, brick and steel fiberglass is used in construction recently. This means that while the service life of the list of the most common materials in construction is known to a sufficient extent, manufacturers do not dare to use fiberglass as a material for critical structures. This occurs because changes in its characteristics, depending on operational factors, are not sufficiently studied for intervals exceeding 4-5 years of operation. Materials and methods. During the work, samples of fiberglass SPPS with a longitudinal and transverse arrangement of fiberglass were tested for climatic aging in a climatic chamber for 5 cycles simulating 5 years of material operation. All samples were subjected to tensile testing on a tensile testing machine R-5. Results. Destructive stresses were determined, calculations were carried out and elastic and strength characteristics of the samples were analyzed. On the basis of the obtained results, an analysis was carried out, conclusions were formulated about the use of fiberglass in the construction in the long term, as well as the influence of such operational factors as moisture, positive and negative temperatures, and ultraviolet radiation on the properties of fiberglass with a different arrangement of fiberglass. Conclusions. Found that the destructive stresses of fiberglass are significantly reduced during the first two years of operation, which must be considered when choosing fiberglass with the stated characteristics. Ultraviolet does not have a significant effect on the elastic-strength properties of the material, while during operat

DOI: 10.22227/1997-0935.2018.12.1509-1523

Download

Results 1 - 2 of 2