"Вестник МГСУ"

The article deals with the analysis of embankment dams of a new type: a rockfill dam with a clay-cement concrete diaphragm built by bored-pile method. The authors give the results of numerical modeling of a stress-strain state of 69 m high dam, where a diaphragm in the form of a slurry trench cutoff wall cuts the whole dam body and a23 m deep gravel-pebble foundation. The co-authors describe a dam design where the diaphragm is constructed in three lifts. The diaphragm lifts are connected by slabs made of clay-cement concrete or clay. Numerical modeling was carried out with the use of the author’s computer program with consideration of non-linearity of soils deformation. Analyses showed that clay-cement concrete of a slurry trench cutoff wall is in a favorable stress state, as clay-cement concrete by its deformation characteristics (E = 100 МPа) is close to gravel-pebble soil. The diaphragm deflections turned to be small; therefore, tensile stresses will not occur in it. In the diaphragm the clay-cement concrete is in a state of triaxial compression, therefore, its strength will be higher than unconfined compression strength (1-2 МPа). It may be expected that its strength will be provided. The nodes of connection of the slurry trench cutoff wall lifts also demonstrate safe operation.

The article presents the results of the first stage of the model research of the river downstream currents in the water transport hydroscheme and the analysis of their influence on the channel processes and navigation.The author presents a justification of the method of river flow research using the pressure aerodynamic model. The model is a geometrically similar part of a river with the hydroscheme of 1200 m length in nature. As a result of the research the velocity profiles were indentified in six sections along riverbed, the geometric dimensions of a whirlpool were discovered, the areas of the most intensive exposure of the river flow to the banks were identified, the navigable conditions were specified on the way to the lower head lock, the recommendations for the river banks protection from erosion have been given.

Irrotational flows produced by spatial linear flows of finite length with different uneven lows of discharge over the flow length are represented in cylindrical coordinate system. Flows with the length 2a are placed in infinite space filled with ideal (inviscid) fluid. In “А” variant discharge is fading linearly downward along the length of the flow. In “B” variant in upper half of the flow (length a) discharge is fading linearly downward, in lower half of the flow discharge is fading linearly from the middle point to lower end. In “C” variant discharge of the flow is growing linearly from upper and lower ends to middle point.Equations for discharge distribution along the length of the flow are provided for each variant. Equations consist of two terms and include two dimensional parameters and current coordinate that allows integrating on flow length. Analytical expressions are derived for speed potential functions and flow speed components for flow speeds produced by analyzed flows. These analytical expressions consist of dimensional parameters of discharge distribution patterns along the length of the flow. Flow lines equation (meridional sections of flow surfaces) for variants “A”, “B”, “C” is unsolvable in quadratures. Flow lines plotting is proposed to be made by finite difference method. Equations for flow line plotting are provided for each variant. Calculations of these equations show that the analyzed flows have the following flow lines: “A” has confocal hyperbolical curves, “B” and “C” have confocal hyperboles. Flow surfaces are confocal hyperboloids produced by rotation of these hyperboles about the axis passing through the flows. In “A” variant the space filled with fluid is separated by vividly horizontal flow surface in two parts. In upper part that includes the smaller part of the flow length flow lines are oriented downward, in lower part – upward. The equation defining coordinate of intersection of this flow surface and flow is also provided. In “B” and “C” variants horizontal flow surface passes through the center of the flow and its discharge is divided in this point in two equal parts. Equation of flow discharge dependence of discharge of fluid between the two flow surfaces is provided for each variant. These equations allow calculating fluid discharge between the two flow surfaces for known flow discharge and vise versa calculating flow discharge for known discharge between the two flow surfaces. The analyzed flows meet the conditions of flow potentiality and continuity.

Cultivation of sea objects is of great importance while solving the problems of providing the constantly growing requirements of the national economy with sea products. Cultivation of sea objects uses special hydrobiotechnical constructions. As the practice showed, cultivation of seafood is commercially impossible without solving the questions of calculating and designing such constructions. In special literature these questions are poorly covered or not considered at all. In the article the results of theoretical and pilot studies of waves influence on hydrobiotechnical constructions is provided, in particular on underwater fish-breeding cages.This article offers the theoretical solution to the problem of determining the efforts of the ropes holding the fish tank under wave influences. In order to solve this problem, the equations of hard drives movements were set up and the differential equations of free oscillations of buzz were obtained.When determining the horizontal movements, the four different configurations of connections and the system motion directions in general are possible in case of waveoscillations. Next step is the solution of the differential equations and determination of natural oscillation frequency in the direction of the vertical axis. Defining efforts in the ropes from their own weight (static calculation) is self-explanatory, it should be noted that accounting for the weighing influence of water on such structures does not have significant influence.Further the authors defined loading and efforts from the regular waves’ impacts.Modeling of the waves influence on submersible fish tank was carried by Fraud method. The studies were conducted with two models with large and small mesh. The signals of strain gauge sensors were registered by electronic measuring equipment.When comparing the theoretical and experimental data, satisfactory results have been obtained. It was determined that in order to improve the calculation methods it is appropriate to carry out an additional series of experiments for the refinement of the permeability coefficient, which is included in the calculation of the wave load.

This paper presents a study of the scour in front of the breakwater caused by oblique waves influence. The experiments were conducted to investigate this scour. The experimental results indicate that the maximum depth of scour hole is observed near the breakwater. The scour depth increases as a wave period and incident wave angleincrease. While comparing the present experimental results with the previous study, it is found out that the scour caused by oblique waves influence considerably differs from the scour caused by the influence of straight waves. Breakwater is an important component of a sea port. It is intended to protect the port water area from the impacts of waves, currents and sediments. The scour in front of the breakwater may occur as a result of waves and currents. It may cause the damage of a construction and stop the proper functioning of the port. Therefore the study of scour is an important task of hydraulic construction.When oblique waves approach the breakwater the system of three-dimensional waves are formed, which are called “short-crested waves”. These waves generate a current along the breakwater front. The current interacts with the ground and causes erosion of the bed. This mechanism differs from the mechanism of erosion in the case of frontal approach of waves when the standing waves are formed. Namely, erosion of the bed is the result of the wave velocity increase due to the reflection of waves at the structure. However, in engineering practice of hydraulic structures design, the influence of oblique waves is neglected and is taken into account only in case of the regular incoming of the waves.

This paper considers a possibility of booms application at spillway dams in order to reduce gates size and capacity of weight lifting device without changing weir discharge capacity. The prospects of booms application at weir top were proved during hydraulic researches conducted at JSC “NIIES” (Joint Stock Company “Scientific Research Institute of Energy Structures”). Basing on the conducted researches the recommendations of booms application at spillway facilities of Yumaguzinskaya and Upper Krasnogorskaya hydropower schemes, as well as at spillway facilities of Sayano-Shushenskaya and Plyavinskaya hydropower plants have been worked out. The main factor limiting wide application of booms at weirs is lack of feasible data for designing. At first, this data has to conclude methods of defining spillway discharge capacity and elevation of boom installation, which allows to keep the same spillway discharge capacity at rated head. The equations to define optimal elevation of boom installation and weir discharge capacity without its submergence have been analytically obtained for nappe-crested weir with installed boom. At the present time it is needed to conduct methodical experimental studies to define the discharge ratio and vertical compression according to different types of booms.

Technological features of cultural reproduction of seafood presuppose the use of hydrobiotechnical constructions. Calculations of the loadings and impacts on sea hydrobiotechnical constructions demand a reasonable choice of a hydromechanical theory of wave movement. In the article the theories of two-dimensional regular linear and nonlinear waves are considered: the theory of small amplitude waves; Stokes' wave theory (the second order of approximation); the theory of final height waves of the first, second and third order of approximation. The dependences for determining speeds and accelerations of liquid particles are given. The comparison results of various theories of regular waves and fields of their application are stated. The authors offer the expressions for engineering calculations of kinematic characteristics of regular waves at a final depth. In recent years, cage culture fishery has received the predominant development in marine aquaculture, because its creation do not require large investments. Calculation of loads and impacts of waves on the shore hydraulic structures under extreme conditions require justified choice of hydro-mechanical theory of wave motions. This article gives a comparison of the various theories of regular waves, both linear and nonlinear and evaluates the applicability of them from the point of view of engineering use and actual conditions. However, the theory of small amplitude waves is widespread both in theoretical studies and engineering application, due to its sufficient simplicity and the fact that the linearity of the theory of small amplitude waves allows using the method of summing elementary solutions in the process of finding potential wave motion. The choice of one or another wave theory in marine facilities calculations of regular waves impact depends on the type of design, ease of using wave theory in calculations, type of the considered impact, applicability of the different wave theories in order to correctly describe the characteristics of wave motion in different wave zones.

The article is devoted to the analytical study of the structure of steady non-uniform creeping flow in a cylindrical channel. There are many papers on the hydrodynamics of such flows, mainly related to the production of polymers. Previously we showed that the structure of steady non-uniform creeping flow in a cylindrical tube is determined by the Laplace equation relative to the azimuthal vorticity. The solution of Laplace's equation regarding the azimuthal vorticity is dedicated to the first half of the article. Fourier expansion allows us to write the azimuthal vortex in the form of two functions, the first of which depends only on the radial coordinate, and the second depends only on the axial coordinate. Fourier expansion can come to the Sturm - Liouville problem with a system of two differential equations, one of which is homogeneous Bessel equation. The radial-axial distribution of the azimuthal vorticity in the creeping flow is obtained on the basis of a rapidly convergent series of Fourier - Bessel. In the next article the radial-axial distribution of the stream function will be discussed. The solution is constructed from the Poisson equation based on the solution for the azimuthal vortex distribution. Fourier expansion can come to the Sturm - Liouville problem with a system of two differential equations, one of which is inhomogeneous Bessel equation. The inhomogeneous Bessel equation is solved through the Wronskian. The distribution of the stream function is obtained in the form of rapidly converging series of Fourier - Bessel.

Hydraulic engineering constructions or dams are necessary constructive elements for river development. In severe climatic conditions (deep-frozen soil, low temperatures, high amplitudes of temperature fluctuations) the most expedient type of water retaining constructions are soil dams. In our paper we have examined economic conditions of the region with severe climate, available water resources and their development. We made the conclusions concerning preference for building reservoirs on the territory of Siberia. A two-century period, beginning with the first soil dams in the end of the 18th century, was considered for the building analysis. Our attention has been mainly focused on structures, engineering decisions and causes of accidents, which took place in operating cycle period. The results showed the importance of investigation of filtration and temperature regimes, as well as their collaboration in hydro technical structures design and operation.

The article is a further research of a circular-longitudinal flow created in a cylindrical pipe by a continuous swirler called Couette vortex, which the author started to study in his previous works. The key question is how Couette modified vortex is transformed along the channel (pipe). The author regards variation of azimuthal velocities (
u) and the Heeger-Baer’s swirl number (
Sn) in turbulent irregular circular-longitudinal flow, which is described by the model of modified Couette vortex along the cylindrical channel. It is confirmed that the model of the modified Couette vortex and free-forced Burgers - Batchelor vortex show almost similar results in calculations and both vortex models can be equally used in engineering practice in calculations and the analysis of circulating and longitudinal flow operating modes (vortex flows).

This article focuses on the method of improving shear stresses calculation accuracy based on the experimental data. It was proven that shear stresses value considerably changes (even up to change of sign from positive to negative) depending on different velocity fluctuations amount (or length). Experimental database consists of velocity in turbulent flow at different times. Recommendations for practical use of methods of calculation depending on the type of engineering problems are presented. The method of finding optimal amount of the experimental database is proposed by the analysis of the values convergence of the standard deviations calculated for the whole sample and the standard deviation calculated by increasing interval. The calculation results for these intervals are at the points of the measuring system and the hypothesis about finding the optimal length of implementation is offered. The steps for further research are set out.

In the process of calculating and simulating water discharge in free channels it is necessary to know the flow features in case of small values of Reynolds and Weber numbers. The article considers the influence of viscosity and surface tension on the coefficient of a weir flow with sharp threshold. In the article the technique of carrying out experiments is stated, the equation is presented, which considers the influence of all factors: pressure over a spillway threshold, threshold height over a course bottom, speed of liquid, liquid density, dynamic viscosity, superficial tension, gravity acceleration, unit discharge, the width of the course. The surface tension and liquid density for the applied liquids changed a little. In the rectangular tray (6000x100x200) spillway with a sharp threshold was established. It is shown that weir flow coefficient depends on Reynolds number (in case Re < ~ 2000) and Webers number. A generalized expression for determining weir flow coefficient considering the influence of the forces of viscosity and surface tension is received.

In the article the authors estimate the possibility of building a high (100 m high) stone dam with clay-cement concrete diaphragm. This diaphragm is used as an antifiltering element and it is made of secant piles method of clay-cement concrete (method of "slurry wall"). This diaphragm should be constructed in several phases, in our example example in three stages. Numerical studies of the stress-strain state of such a dam show that considerable compressive stresses can appear in the diaphragm. These stresses can be significantly (3...4 times) greater than the strength of clay-cement concrete in compression. However it should be taken into consideration that the diaphragm of such a high dam will be crimped by horizontal stresses, i.e. clay-cement concrete will operate in the triaxial compression. Under these conditions the strength of clay-cement concrete will be significantly higher, therefore, the diaphragm reliability might be provided with a margin. For this reason, the most important issue in the engineering of a high dam with such type of diaphragm is to select the required composition of clay-cement concrete. Increasing its strength by extension of the cement fraction could increase modulus of deformation. Therefore it could lead to compressive stress increase and the strength state degradation. Hydrostatic pressure generates the areas of tensile stresses in the clay-cement concrete diaphragm due to the arising bending deformation. It threatens the formation of cracks in the clay-cement concrete, especially in the nodes interface diaphragm queues. It is recommended to match the diaphragm queues using ferroconcrete galleries. This should ensure flexibility of deformation between the gallery and the diaphragm.

The co-authors offer a new method designated for the measurement of the liquid level inside hydrostatic and hydrodynamical elevation meters. This innovative leveling method prevents any temperature influence on the measurement results in each vessel, although the temperature inside the vessels does not need to be measured. The result is reduced to the base temperature value inside each vessel. Another strength of this method consists in its insensitivity to the liquid temperature in the vessels or to the difference of temperatures. Moreover, there is no need to be aware of the function describing the temperature to density correlation, whereas the accuracy that ensures the prevention of any influence of the temperature-induced error is solely determined by the accuracy of the liquid level registration alongside the top edge of the float. Besides, the temperature range being measured is unimportant, although it must remain within the limits that assure the preservation of the water properties (to prevent boiling, freezing, etc.).

The co-authors have designated the point for the identification of the critical velocity and intensity of the hydro-abrasive wear within the framework of the two-phase flow mechanics challenges. In this article, the two-phase flow is analyzed as the flow that has the solid phase, including ore particles, concentrates and tailings, solid fuel combustion products, sand, and construction materials, etc., and as the flow containing the liquid phase, or water. The authors have identified the influence produced by the presence of fine-dispersed solid particles in the two-phase flows that transport the milled ore concentrate due to the presence of the water. Variations in critical velocity values, driven by the per-cent clay content in the ore, were exposed to the experimental research performed by the Laboratory of Hydraulic Transportation at the Hydraulics Department, MGSU. The experimental data are consistent with the findings of the analysis of the influence produced by dust fractions on the critical velocity at the Eastern site’s placer of Malyshev deposit. The co-authors offer their methodology for the refinement of the critical velocity analysis depending on varied per cent clay content values; the diagram compiled in relative coordinates, and the approximative correlation required for practical applications. The proposed methodology consisting in feeding fine-dispersed additives into the two-phase flow, reduces the critical velocity.

The article has summarized findings of the research into the stress-strained state of the concrete dam. Within the framework of this project, the co-authors have analyzed particular features accompanying field data processing, if the concrete dam serves as the data source. The co-authors have derived average linear expansion coefficients for frozen concrete samples originating from varied dam zones. The findings of numerical studies are provided with the account for the variable value of the linear expansion coefficient of the concrete exposed to negative temperatures. Specialized contact methods in finite elements simulations were employed to simulate the casting joints, with the monolith height being equal to 1.5 m, to take account of the non-linear shear strain of joints and their opening. The analysis performed by the co-authors is based on the combinations of loads and other exposures typical for January as the coldest month of an average year. Casting joints were only simulated in the bottom of the finite element dam model, while no joints were simulated for the dam top. The findings have proven, that the 1.53-fold rise in the value of α accompanying concrete freezing, influences the strain state of the dam at Bogouchanskaya hydropower plant. However no effect was produced by the change in the α value onto the strain state of the dam face. Besides, the rock-to-concrete contact depth and width increased. Although, given the small value of the aforementioned increase (decimal points of a millimeter), it will produce no effect on the filtration underway within the bedrock base of the dam. Changes in the value of the linear expansion coefficient of concrete must be taken into account when physico-mechanical characteristics of concrete are identified for the purpose of the finite element analysis.

In the article, characteristic values of dynamic sizes of bottom and suspended sediments, including their probabilistic assessment, are considered. The article presents the processing results in respect of the experimental data for bottom and suspended sediments, obtained in the laboratory environment using samples and filming methods. The experiments have proven that the dynamic hydraulic size determines the height of rise for the particles of the saltation load, rather than suspended ones. In the laboratory environment, the maximal height of rise is mainly driven by the relative flow depth. According to the assessment made by the co-authors, depths of flows employed in the experiments designated for the identification of heights of rises, were comparable to saltation heights of particles. Besides, the saltation height of particles, having relative density well below 2.65, nearly always exceeded half of the depth of the laboratory flow. Hydrodynamic conditions favourable for the separation and motion of artificial particles in coarse surface tanks are far different from the motion of sand particles on the bottom of lowland rivers. Values of hydraulic resistance ratios typical for laboratory experiments by far exceed their values typical for lowland rivers, and it means that the conditions of the experiments performed in the laboratory were similar to those typical for mountain rivers. The research findings have proven that the particle separation and motion pattern, if artificial particles are made of the materials demonstrating variable density and elasticity values and if loose particles travel over fixed ones, is different from the pattern typical for natural particles having variable coarseness.

Water disposal constructions are one of the most responsible constructions of reservoir hydrosystem, that’s why the a lot of attention was always paid to the problems of estimating and providing their reliability and safety. The most important function of such objects is providing reliability and safety of other hydraulic constructions and economic assets in afterbay and water head. The authors offer estimation method for reliability and faultless performance of reserved water disposal with erodible fuse plug on low-head water development. In order to estimate the reliability of reserved water disposal with erodible fuse plug the Bayesian treatment was used. The calculation of diagnoses (states) of reserved water disposal isoffered in case of diagnostic properties k
1 and k
2. One of the main demands placed onreserved water disposals is erosion of soil plug in case of flood discharge exeedance over the estimated frequency with the full opening of the waste sluice.

In the article the authors analyze numerical modeling results of the stress-strain state of a combined dam created by construction of a higher rockfill dam with a reinforced concrete face behind the downstream face of the concrete dam. The analysis was conducted on the example of the design of 150 meter high New Exchequer dam (USA). Numerical modeling was conducted with consideration of non-linearity of soils deformation as well as non-linear behavior of the interaction “concrete - soil”, “concrete - concrete”. The analysis showed that though in a combined dam the concrete part gets additional displacements and settlements, its stress state remains favorable without appearance of tensile stresses and opening of the contact “concrete - rock”. This is explained by the fact that on the top the concrete dam is weightened by the reservoir hydrostatic pressure. The role of rockfill lateral pressure on the concrete dam stress state is small. There may be expected sliding of soil in relation to the concrete dam downstream face due to the loss of its shear strength. Besides, decompaction of the contact "soil - concrete" may occur, as earthfill will have considerable displacements in the direction from the concrete dam. Due to this fact the loads from the earthfill weight do not actually transfer to the concrete dam. The most critical zone in the combined dam is the interface of the reinforced concrete face with the concrete dam. Under the action of the hydrostatic pressure the earth-fill under the face will have considerable settlements and displacements, because soil slides in relation to the concrete dam downstream face. This results in considerable openings (10 cm) and shear displacements (50 сm) in the perimeter joint. The results of the numerical modeling are confirmed by the presence of seepage in New Exchequer dam, which led to the necessity of its repair. Large displacements do not allow using traditional sealing like copper water stops in the perimeter joint of combined dams. The sealing should be made of geo-membrane with placement of an asphalt pad under the face. Due to bending deformations in the lower part of the reinforced concrete face considerable tensile forces may occur. It is recommended to arrange a transverse joint in this part of the face.

The purpose of this paper is to design rationale for the use of protective pads of geotextiles and geomembranes permeability of PD using these pads. In order to justify the use of protective pads made of geotextile for reducing the defectiveness geomembrane soil fractions, the existing formulas to determine the thickness of the film element of impervious devices were examined. The calculations according to the formulas show that HDPE geomembrane with a minimum thickness of 1,0 mm, the protective lining of the geotextile should be applied at the average diameter fractions of soil of more than 6,5 mm, and for geomembranes HDPE - at a diameter of soil fractions of over 15,5 mm. In order to estimate the permeability of the TFG geomembrane using additional protective linings of geotextile in the scientific article the basic design schemes of such coatings with one and two layers of protective linings of geotextiles were considered. The evaluation results of water permeability of impervious surfaces with geotextile and for comparison - without geotextiles are given in a table. As it is shown by the data presented for the design scheme with a single layer of geotextile geomembrane at the base (in the presence of small holes in the geomembrane) the decrease the effectiveness of an anti-covering is more than 268,0 %, and for the settlement scheme covering with two layers of geotextile there will be a very large reduction in the efficiency, which almost completely reduces the effectiveness of the coating to the value of the geomembrane permeability of a soil layer without geomembrane with the filtration flow rate of 71,75 m
3/day, against water permeability of the geomembrane cover - 38,52 m
3/day. From the foregoing, it can be concluded that the application of a coating design of well filtering gaskets made of geotextile is justified in terms of protecting the geomembrane from mechanical damage, but greatly reduces the effectiveness of impervious cover in case of its damage.