Experimental assessment of soil effects on the leakage discharge from polyethylene pipes

Abstract

Leaking water from pipes depends on several factors such as pressure, pipe material, types of cracks and holes and also regime of flow through cracks. The effects of these factors on the leakage have been investigated by several researchers. However, few studies have been found considering the effects of soil around the pipes on the leakage discharge. Here, the leakage from polyethylene pipes is simulated in the laboratory, selecting several soils with different specifications. The leak discharge equation is adjusted to evaluate the effects of soil characteristics. Accordingly, grain diameter greater than 10% and 50% passing, coefficient of uniformity, coefficient of curvature, liquidity limit, plastic limit, plasticity index and hydraulic permeability have been considered to represent the soil properties. It is observed that the leakage is changed in accordance with most of the above parameters. The effects of grain diameter greater than 50% passing, plastic limit and hydraulic permeability are higher on the leakage, comparing to those of other parameters. However, no meaningful relationship is observed between the leakage and some parameters. The effects of significant characteristics are shown by the equations presented in this study.

Experimental Investigation of Leakage Flow Rate and Fluidisation beneath Polyethylene Pipes in Non-Uniform Soils

“…The discharge coefficient of the hole is significantly higher than the cracks, while it is higher in free air than in soils. Although [14] investigated the same results for uniform soils, this research confirms their conclusion for non-uniform soils. Figure 6 shows variations in the leakage discharge coefficient in regard to the crack length.…”

“…Table 2 shows that the value of leakage power for 14, 17 and 20 mm cracks is between 0.86 and 1.91. However, the value of the leakage exponent for the hole used in the present study was observed to be slightly less than 0.5, which may be due to the elasticity of the polyethylene material [14].…”

“…Latifi et al [14] demonstrated a strong correlation between leakage and specific factors, namely grain diameter over 50% passage, plastic limit, and hydraulic permeability. In a subsequent study, Latifi et al [15] conducted experimental investigations on pipe leakage with various soil compositions.…”

Effect of hydraulic and geometric factors upon leakage flow rate in pressurized pipes

“…P = P atm = 0 (gage). It is true that the leakage flow rate modeled in the absence of soils (outlet to atmospheric pressure), as assumed in our study and in most of the laboratory relations (Equations 1, 2, and 4) used in the computational models, may be higher compared to those of field conditions with the presence of soil (Latifi et al, 2018). Nevertheless, for high soil diffusibility (e.g.…”