DEFОRMATIОN PRОCESSES IN THE DОWNSTREAM ОF MULTI-SECTIОN WATER ОUTLET STRUCTURES

АННОТАЦИЯ

В статье представлены исследования методов гидравлического проектирования и расчета многосекционных водосбросных сооружений, процессов деформирования или смывания в этих сооружениях и причин их возникновения.

ABSTRACT

The study оf the existing hydraulic design and calculatiоn methоds оf multi-sectiоn water discharge structures, the defоrmatiоn оr washоut prоcesses in these structures and the reasоns fоr their оccurrence are given.

Ключевые слова: многосекционный, деформация, нижний бьеф, гаситель, гидравлический прыжок.

Keywоrds: multi-sectiоn, defоrmatiоn, bоttоm beef, quencher, hydraulic jump.

The study of the existing hydraulic design and calculation methods of multi-section water discharge structures has different conditions for studying the processes of deformation or washing, i.e. damage and the causes of their occurrence in these structures. Research and observation works and archival materials performed by specialists of scientific research institutes and projects for constructions in the regions were studied [1, 2].

In the last decade, a number of scientific studies have been conducted to study this issue, and pipeline structures in existing reservoirs in our country have also been studied [3, 4, 5].

Based on the results of these studies, we can give the following results: most of the structures built in the last ten years began to deteriorate as a result of increased deformation processes. Such facilities make up 15-20% of the existing ones. About 40-50% of structures require annual maintenance. The study of the results of research observations fully showed that the main part of these cases is the result of deformation processes in the lower slopes [6]. These results can be divided into the following forms: washing at the end of the embankments, washing of the bottom and banks of the outlet channels;

• breakdown of noises and tight junctions;
• breakdown of extinguishers;
• impact of ground foundations and reinforced concrete areas;
• processes of overgrowth of various plants and siltation in the outlet.

As one of the main reasons for the failure of such sub-bases, it can be recognized that the hydraulic regime of the structure changes frequently.

In most cases, it is observed that the structures work in an unburied state. This, of course, in turn leads to an uneven distribution of speed, fluctuations in hydrodynamic pressure, and the appearance of the clutch in the form of oscillations or distant hydraulic jumps. In practice, it is observed that such a situation occurs especially when hydrotechnical facilities are put into operation. The reason for this, of course, may be some shortcomings in the design, the difference between the project and the construction, failure to take into account complex hydrological and geological conditions, poor quality construction works, or unsatisfactory operation of the user service.

Based on the results of observation in terms of the structure of the structure, the following shortcomings of the hydrotechnical structure can be indicated:

• the lower level of the strengthening work in the lower bef is lower than the required standards;
• the composition of small-sized elements of prefabricated construction elements of buildings:
• low strength in the mutual integration of these elements;
• non-processing of the bases of the plates and their non-interconnection;
• absence of elements of dampers that serve to reduce the high kinetic energy of the flow or incorrect placement without taking into account the dynamics of the flow.

As a result of the shortcomings recognized above, the opening between the elements of the structure occurs as a result of these deformation processes. As a result of the deformation process under the slab, the outcropping of soils causes the horizontal position of the slab to be disturbed, one side to rise, and ultimately the slab to move. This will definitely disturb its balance sheet. The formation of horizontal constitutive forces and shearing moments causes the plate to move downstream. This movement occurs as a result of changes in velocity and hydrodynamic pressure pulsations under and above the plate.

This situation can be recognized as a complete violation of risberma. On the banks of the structure, this situation can be more complicated. The washing of soil beneath the coastal slabs causes it to slide down the coastal slope.

These recognized situations require the improvement of hydraulic calculations performed during the design process, taking into account vibration (pulsation) effects.

In the process of designing pipeline structures of multi-section water discharge facilities, it is necessary to solve the following issues:

• perform the hydraulic calculation of the connection of pipelines;
• correct selection of the type and parameters of extinguishers that prevent hydraulic processes affecting the structure (prolonged or wave-like hydraulic jumps) for different situations of moving barriers of the hydraulic structure;
• to know the main elements of the flow in all reinforcement elements - the depth, the magnitude of the components of averaged and average velocities and pressure pulsations. Based on these values, it is possible to carry out hydraulic calculations to determine the distances of strengthening in risberm, water impact wells. The strength of the soils under the slab, the filtration process, the structural constructions and the sizes of all the elements of the bottom bef are determined [4;5].

The washing parameters of the bottom and banks of the channel in the lower bay are determined.

The choice of effective constructive solutions for such complex issues is a general issue, and it is necessary to carry out the design in a comprehensive manner, taking into account the technical and economic aspects.

Today, there are a huge number of hydraulic and hydrodynamic calculation methods based on field and experimental research and theoretical solutions to solve these problems. Now it is necessary to bring them to such a level with the method of improvement that the resulting solutions should ensure the optimal operation of the facility.

This is done as a result of the relevance of improved hydraulic calculations, the use of unified structural solutions in hydraulic engineering practice.

Currently, the methods used in practice and applied are being improved. The results of the conducted scientific research cannot be used directly to solve engineering problems, some of them have not been proven by experimental research.

Different interpretations of existing hydraulic, hydrodynamic and strength calculation methods, conflicting results and other reasons make it difficult to choose the most effective one.

It is for this reason that it is necessary to choose the appropriate generalized methods for each type of pipeline construction.

Reference:

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