Mathematical modeling of stress-strain state of the system HPP building - soil base with account for the phased construction of the building

• Main Author: Orekhov Vyacheslav Valentinovich
• Format: Article
• Language: English
• Published: Moscow State University of Civil Engineering (MGSU)
• Series: Vestnik MGSU
• Subjects: phased construction; settlement of the bottom plate; hydro power plant; numerical simulation; stress-strain state; soil foundation
• Online Access: http://vestnikmgsu.ru/files/archive/issues/2014/12/ru/11.pdf

The interaction process of a power plant building with the soil base is studied basing on mathematical modeling of the construction process of Kambarata-2 HPP, taking into account the excavation of foundation pit, the concreting schedule of the building construction, the HPP units putting into operation and territory planning. Mathematical modeling of stress-strain state of the system “power plant - soil base” in the process of construction was performed by using the computer program “Zemlya” (the Earth), which implements the method of finite elements. Such a behavior of soil was described using elastoplastic soil model, the parameters of which were determined from the results of the triaxial tests. As shown by the results of the research, the continuous change of settlement, slope, deflection and torsion of the bottom plate and accordingly change of stressed-strained state of power plant are noted during the construction process. The installed HPP construction schedule, starting from the construction of the first block and the adjacent mounting platform, is leading to the formation of initial roll of bottom plate to the path of the mounting pad. In the process of further construction of powerhouse, up to the 29th phase of construction (out of 40), a steady increase in its subsidence (maximum values of about 4.5 cm) is noted. Filling of foundation pit hollows and territorial planning of the construction area lead to drastic situation. In this case, as a territory planning points exceeded the relief, the plastic deformation in the soil evolves, resulting in significant subsidence of the bottom plate under the first block (up to 7.4 cm). As a result, the additional subsidence of the soil of bottom plate edges lead to the large vertical movement in relation to its central part and it is bent around the X axis, resulting in a large horizontal tensile stress values of Sz (up to 2.17 MPa) in the constructive elements of the upper part of the powerhouse. At the same time, the calculations performed on the assumption of instantaneous power plant construction forecast only a uniform slope of bottom plate in the direction of the headwater and do not allow us to track the process of stress-strain state of the power plant for adequate reinforcement of its elements.