R.A. Kulzhayeva

Taraz State University named after M.Kh.Dulaty, Taraz

ANALYSIS OF EXISTING METHODS OF SIMULATION OF CHANNEL PROCESSES FOR eroded MODELS

Considering the brief analysis of existing methods of modeling channel processes, it should be noted that the nature of the formulas used for connections between the main scale factors can be conditionally divided into three groups:

a) methods based on the use of morphometric bound bonds between the width and depth of the channel;

b) methods based on applying the criteria of the mobility of sediment and sediment flow;

c) methods based on the formulas of the first and second second group together with the Chezy formula.

The methods of modeling only establish a connection between the main factors and scale. All other scaling factors - the scale of expenditure, the scale space, scale, speed, time scale etc. Are derived from the set of scale factors and is determined by cconversion of the known dependencies.

Existing methods of simulation of the distorted channel processes used by nature calculated relations for the basic of counting scale factors can be divided into the following groups:

a) methods based on the use of gidromorfometricheskih relationships and establishing mutual bound between the vertical and transverse scale. In the literature, this method is known as a natural method of modeling;

b) methods based on applying the stability criterion of sediment and the values of the solid flow and the mutual relationship between the vertical and transverse e scale.

v) methods based on the accounting rate of the mobility of bottom sediment and the Chezy formula.

The group "a" include methods Velikanova A.M, Altunina S.T, Lepshenkova V.S [1, 2, 3].

The group "b" includes methods of Levy I.I and Pikalova F.I [4, 5].

The group "v" are the methods developed Altunin V.S and Rzhanitsinym N.A [6, 7].

For reliable analysis of the above methods of modeling of channel processes to all of them to investigate the compliance of the boundary conditions.

Detailed understanding of the methods in any case completely all the calculated ratios do not converge. This, perhaps, explained discrepancy is proposed methods and the final results of the verification required quantities. Many techniques do not take into account the scale factors share eroded soil and sediment particle diameter, making up the lodge. Sometimes on certain methods while respecting the boundary conditions and , that meets strict criteria on Froude modeling without any distortion of horizontal and vertical scales, we obtain an absurd result, expressed in non-compliance imposed boundary conditions.

Naturally, these methods can not be broadly applied. Along with these observations should be noted that the proposed modeling techniques mainly based on the vertical and transverse scales. As is evident from the analysis, depending on the method in question occurs and the longitudinal scale of the model. This approach, of course, in the studied process introduces a certain ambiguity, it is difficult to give preference to existing methods modelirovaniya masshtabov. Therefore we must always strive to ensure that the longitudinal and transverse scales are equal. In group "a"of the available methods to this conclusion does not, as in the main analysis is based on data on the lateral stability of the channel. Under these conditions, mainly examines the influence rusloformiruyuschih factors on static stability of the channel in this section and not paid attention to the longitudinal stability of the channel. It seems to us that when considering the stability of the channel should be particularly pay attention to longitudinal stability, because it can serve as a basis for the erosion of the and, in the light of deformability: it can lead to a breach of the stable areas. Therefore the methods relating to a group "a" may be used only for indicative prikidok for model studies.

Methods of group "b" based on the application of the criterion of the mobility of sediment, compared with the above method "a" are more progressive and take into account the longitudinal channel stability in conjunction with transverse stability section. This approach makes the well-known certainty in the process studied, and in particular, to equate the longitudinal and transverse extent of channel stability. However, considering only the stability of the eroded particles on the bottom, the authors have not paid attention to the dynamic effect of the stream bed of blur, and the resulting scale factors do not reflect the true relation of the dynamic impact and resilience of the channel. Consequence, the obtained scaling factors have a large stock of the calculations and, as a rule, lead to the investigation of large-scale models, which is not always possible.

Method of "v", based on applying the criterion of the mobility of sediments in the self-zone, using the principle of dynamic influence of a stream so blur lozhe and take into account the resistance of the soil in the form of equations of Chezy, have, in our opinion, the proper physical foundation. With this approach, automatically succeeds the equality of longitudinal and transverse extent of the model and negates that uncertainty, which is usually common in simulation models, distorted, and is expressed in non-compliance of the above quantities. However, it should be noted that the resulting scale factors are not mutually linked. This should be expected, since the formula Chezy, showing the average flow velocity in uniform motion does not address the physical and mechanical properties of eroded soil. So naturally, the scale factors involving the properties of eroded material in the form of scale proportion, scale, particle diameter and the eroded soil scale heterogeneity of the material eroded in the basic absent in of counting curves. This circumstance is the main drawback of modeling group «v» and hinders their widespread use in research practice.

As you know, when setting scale factors, we can only use the three elements that characterize the eroded soil and model:

a) plan or vertical scale of the model;

b) the scale of the diameter of the eroded soil;

c) the density of the material.

All other scaling factors must be determined uniquely from the main estimated of dependence.

Unfortunately, the group methods "in", as well as methods of "a" and "b " contains no such generalized relations, one linking all the scale factors estimated single dependency.

Therefore, the calculated curves obtained by numerous researchers treated differently. The basis of this discrepancy must be seen in the fact that the scaling factors are based, from an isolated consideration of each of the determining factors.

In particular, the criteria are respected mobility stream deduce of the connection between the longitudinal scale models and scale of specific gravity of soil and from the equation Chezy establish relations scale factors vertical scale and the scale of particle size. The latter is estimated based on the replacement ratio of roughness coefficient channel across the diameter of soil particles from the known formula Shtriklera-chung and by submitting in the scales factors. As a consequence of this approach mainly deals with the case corresponding to a statically stable cross section, ie considered channel stability in the absence of transported sediment in the stream. This is not true, because the flow in natural conditions can carry a certain amount of suspended particles in commensurate with the kinematical characteristics.

However, the main drawback of all existing methods of modeling is that in the calculation of the Chezy formula is introduced, which does not take into account the basic physical and mechanical properties of eroded soil. Hence, we arrive at the main conclusion, namely that of counting dependencies must be mutually linked to all the scale factors, as characterizing the stable channel section , and all the scaling factors that take into account the basic properties of the model

and full-scale ground. We believe that the "a" possible in the sluchaev when the method "in" to close the system of equations will be used not Chezy formula, which expresses the speed of uniform motion, as permitted by the speed. As is well known, includes all the main characteristics of eroded material: specific weight of the soil, the diameter of eroded particles and particle size distribution curve. Such an approach generally will provide an opportunity to close the equations and obtain the scale factors interlink channel stability in connection with the scaling factors of eroded soil

In the design of large channels in the earthen channel

(Kara-Kuma, the Irtysh-Karaganda Tasmuryn, Keles, etc.) for economic reasons, protective measures are not envisaged.

The task of designing such channels include selection of the optimal size of the channel width and depth of content, for which there will be no corresponding deformation of the channel.

One of the reliable methods of forecasting of a large channel should be regarded as a method of physical modeling, the for model will be created and all the boundary conditions corresponding to nature.

Bibliography

1. Velikanov M.A Channel processes. – M.: Fizmatgiz, 1958g, 396s.

2. Altunin S.T Modeling eroded river beds and river structures. - Channel processes, M.1958g. - 215s.

3. Lapshenkov V.S Prediction of channel deformations in the pools of river hydro. - L.: Gidrometeoizdat, 1979g, 240 pp.

4. Levy I.I Simulation of hydraulic phenomena. M. - L.: Gosenergoizdat, 1960g.

5. Abduramanov AA Hydraulics. Taraz. "Taraz universitetі, 2000. – 400s

6. Altunin V.S Reclamation canals in earth channels. - M.: Kolos, 1979g. - 256s.

7. Rzhanitsyn N.A Modelling of natural channel flow. In Sat "Channel Processes, Moscow, 1958g.