THE SLOPE INFLUENCE ON CALCULATED PARAMETERS OF COLLECTING DRAINAGE PIPELINES

Abstract

System of two differential equations, which describe the liquid motion in a drainage pipeline with variable flow rate and the conditions of liquid entry from the surrounding soil through the walls of the pipe in filtration mode, is considered. It consists of a variable mass hydraulics equation and a modified filtration equation. The explored pipeline is laid with a direct slope "i". It is shown that in this case, the second term of modified filtration equation can be neglected without significant error. By introducing new variables, the original system is reduced to a dimensionless form. The solution of this equations system in dimensionless form is presented.

In this case the solution of the original equations system depends on the value of three main factors: the resistance factor of the collecting drainage pipeline "ζ_l"; the generalized parameter "A", which comprehensively takes into account the structural and filtering characteristics of the stream; the geometric slope of pipeline laying "i". The analysis used the concept of an infinitely long drainage pipeline, which is laid with a slope, or, what is the same, an inclined pipeline with an infinite filtering capacity of the side surface walls. It is noted that such pipeline will have the maximum throughput compared to the same pipeline of limited length. Relatively simple and easy-to-use analytical dependencies were obtained on the basis of the conducted analysis. They allow to calculate the nature of the flow rate variations and pressure drop along the length of the drainage pipeline laid with a certain slope.

A series of calculations of the explored pipelines main characteristics were carried out according to the proposed formulas at different values of the slope. Corresponding graphic dependencies were constructed for clarity. It is shown that the value of the geometric slope of the pressure drainage pipeline, along with the resistance factor and the generalized parameter, significantly affects the calculated parameters of such pipelines.