Flow spreading behind a combined dam with a through part of tetrahedrons on foothill rivers

The areas of the foothill rivers are distinguished by large bottom slopes reaching 0.004, with increased kinetics of the flow of more than 0.15, and by gravel-pebble sediments of the river bed and flow. An analysis of the studies performed on the regulatory structures showed that the bulk of them was performed for the conditions of lowland rivers. In the article, a design of a combined dam with a through part of tetrahedrons is proposed. The experiments were conducted in a flume with a rigid bottom and with a variable slope of. The modeling was performed according to Froude in a self-similar area. Experimental studies revealed the presence of two flow spreading modes depending on the bottom slope: a “calm” mode at iД iκр These modes are mainly influenced by the degree of constraint and the Froude number. In the previous articles, a solution to the problem was provided for the case iД 0.3 and the Froude number Fr > 0.15, a “critical mode” is observed. Here, a solution to the problem for this case is given. The problem, in this case, differs from the previously considered one by non-uniform distribution of velocities in the weakly disturbed core, a significant reduction in the length of the vortex zone; the vertical compression of the flow continues to the end of the vortex zone. The versatility of the velocity distribution in the zones of weakly disturbed core and intense turbulent mixing is experimentally substantiated. With theoretical studies, using the basic equations of applied mechanics, a method for calculating the velocity field was developed, and the planned dimensions of the vortex zones were established. The comparison with experimental data showed satisfactory agreement

Parameters of flow asymmetrically constrained by through spurs

Erosion of the banks of rivers brings enormous damage to the national economy of many countries. To combat them, various regulatory structures are being built: longitudinal dams, transverse traverse dams, watertight and permeable spurs, and combined transverse dams. Many issues of their design are sufficiently developed, including in our works, and are successfully applied. This research aims to develop a method for hydraulic flow asymmetrically constrained by through pile-type spurs. The conditions of the planned task of the ratio of the flow width to the depth of more than 6 were also observed. The degree of restriction of the flow by spurs varied from zero to one, and the installation angle of the spurs from 600 to 900. The study of the velocity field showed their similarity with the main provisions of the theory of turbulent jets. The velocity distributions in both zones of turbulent mixing are universal and obey the theoretical Schlichting- Abramovich dependence. The expansion coefficient of the jet is 0.20. Theoretical studies have obtained dependences for determining the velocity in a weakly disturbed core, occurrent flows, and the spreading regions' lengths, which determine the installation locations of subsequent spurs

Kinematic parameters of flow constrained by combined dams with through part of tetrahedra in compression region

Every major river in the world consists of mountainous, foothills, and flat areas characterized by different flow regimes. The foothill areas differ in slopes i = 0.001 ÷ 0.004, flow kinetics Fr > 0.15, and the size of sediments. The riverbed is unstable, and the banks are prone to erosion. The construction of coastal protection structures requires solving complex issues related to their design. The analysis showed that most of the studies, including ours, were carried out for the conditions of lowland rivers. This work aims to establish the flow features of the foothill sections of a combined dam with a through part of tetrahedra when the ratio of the through part ℓs to the total length of the dam ℓd is greater than or equal to 0.5, i.e., ℓs/ℓd. ≥ 0.5 The presence of a satellite flow behind the through part, a weakly perturbed core, and the presence of two zones of intense turbulent mixing was experimentally established, and the universality of the velocity distribution, which obeys the theoretical dependence of Schlichting-Abramovich, was confirmed. It is once again confirmed that the dependence is on the slope of the bottom, the Froude number, the degree of constraint, and the formation of "calm" and "critical" flow modes. The nature of the level changes along the length of the compression region in the core, and the satellite flow differ from each other, and the alignments occur in the vertical compression alignment. The problem is implemented for the "calm" mode using an integral relation characterizing the law of conservation of momentum in the flow, the equation of conservation of flow, and the differential equation of uneven motion recorded for the satellite flow behind the through part of the combined dam. The presence of a satellite flow, two zones of intense turbulent mixing, and the different nature of the leveled regime of the main and satellite flows are taken into account. A comparison of theoretical solutions with experimental ones shows their similarity

Experimental estimation of the parameters of crack progression in concrete

This article presents the influence of the structure on the characteristics of the crack resistance of concrete. Due to ease of manufacture and testing of samples, the method of determining the results of the test KIC beams notched. Depending on the conditions of application of the load, the schemes were used to obtain the characteristics of the crack resistance of concrete in four-point bending, stretching, splitting. They allow to accurately determine stress coefficient KIC

Flow spreading behind a combined dam with a through part of tetrahedrons on foothill rivers

The areas of the foothill rivers are distinguished by large bottom slopes reaching 0.004, with increased kinetics of the flow of more than 0.15, and by gravel-pebble sediments of the river bed and flow. An analysis of the studies performed on the regulatory structures showed that the bulk of them was performed for the conditions of lowland rivers. In the article, a design of a combined dam with a through part of tetrahedrons is proposed. The experiments were conducted in a flume with a rigid bottom and with a variable slope of. The modeling was performed according to Froude in a self-similar area. Experimental studies revealed the presence of two flow spreading modes depending on the bottom slope: a “calm” mode at iД iκр These modes are mainly influenced by the degree of constraint and the Froude number. In the previous articles, a solution to the problem was provided for the case iД 0.3 and the Froude number Fr > 0.15, a “critical mode” is observed. Here, a solution to the problem for this case is given. The problem, in this case, differs from the previously considered one by non-uniform distribution of velocities in the weakly disturbed core, a significant reduction in the length of the vortex zone; the vertical compression of the flow continues to the end of the vortex zone. The versatility of the velocity distribution in the zones of weakly disturbed core and intense turbulent mixing is experimentally substantiated. With theoretical studies, using the basic equations of applied mechanics, a method for calculating the velocity field was developed, and the planned dimensions of the vortex zones were established. The comparison with experimental data showed satisfactory agreement

Kinematic parameters of flow constrained by combined dams with through part of tetrahedra in compression region

Every major river in the world consists of mountainous, foothills, and flat areas characterized by different flow regimes. The foothill areas differ in slopes i = 0.001 ÷ 0.004, flow kinetics Fr > 0.15, and the size of sediments. The riverbed is unstable, and the banks are prone to erosion. The construction of coastal protection structures requires solving complex issues related to their design. The analysis showed that most of the studies, including ours, were carried out for the conditions of lowland rivers. This work aims to establish the flow features of the foothill sections of a combined dam with a through part of tetrahedra when the ratio of the through part ℓs to the total length of the dam ℓd is greater than or equal to 0.5, i.e., ℓs/ℓd. ≥ 0.5 The presence of a satellite flow behind the through part, a weakly perturbed core, and the presence of two zones of intense turbulent mixing was experimentally established, and the universality of the velocity distribution, which obeys the theoretical dependence of Schlichting-Abramovich, was confirmed. It is once again confirmed that the dependence is on the slope of the bottom, the Froude number, the degree of constraint, and the formation of "calm" and "critical" flow modes. The nature of the level changes along the length of the compression region in the core, and the satellite flow differ from each other, and the alignments occur in the vertical compression alignment. The problem is implemented for the "calm" mode using an integral relation characterizing the law of conservation of momentum in the flow, the equation of conservation of flow, and the differential equation of uneven motion recorded for the satellite flow behind the through part of the combined dam. The presence of a satellite flow, two zones of intense turbulent mixing, and the different nature of the leveled regime of the main and satellite flows are taken into account. A comparison of theoretical solutions with experimental ones shows their similarity

Experimental estimation of the parameters of crack progression in concrete

This article presents the influence of the structure on the characteristics of the crack resistance of concrete. Due to ease of manufacture and testing of samples, the method of determining the results of the test KIC beams notched. Depending on the conditions of application of the load, the schemes were used to obtain the characteristics of the crack resistance of concrete in four-point bending, stretching, splitting. They allow to accurately determine stress coefficient KIC