Article citation info: (*) Tekst artykułu w polskiej wersji językowej dostępny w elektronicznym wydaniu kwartalnika na stronie www.ein.org.pl IntroductionThe use of water supply pipes all over the world has always been accompanied by breakages and leakages. What can reduce a number of damages is skilful management of a water supply system and proper maintenance. It is, however, impossible to entirely eliminate such incidents as, most often, they occur randomly [5,7,24]. They can result in financial and social losses [7,8,25,28]. Moreover, leakages can pose a threat to the safety of people and property particularly in urban agglomerations, where water supply systems are located within roadway, constituting an element of an underground utility, as well as in areas of compact settlement [13]. The threat emerges as a result of the particles being washed out from the soil skeleton during the breakage of an underground pipe which can lead to the formation of empty spaces beneath the ground surface and contribute to the creation of depression or holes in the Earth's surface (suffosion processes) [1,4,9]. Such incidents took place worldwide and produced detrimental social and economical effects [22]. Occurrence of internally unstable soils, especially in the range of the loess plateau [2] as well as a high failure intensity rate of water supply systems, compared to other countries [15,16,18,19], are factors which increase the risk of the emergence of such a problem in Poland. IwAnek M, kowAlskA B, Hawryluk e, kondraciuk k. Distance and time of water effluence on soil surface after failure of buried water pipe. laboratory investigations and statistical analysis. eksploatacja i niezawodnosc -Maintenance and Reliability 2016; 18 (2): 278-284, http:// dx.doi.org/10.17531
Saturated hydraulic conductivity (Ks) is an important soil parameter that is difficult to measure, especially in an anisotropic medium. Many methods for determining Ks have been developed over time, but taking different water flow directions into consideration is possible in only a few of them; furthermore, these few methods cannot be universally applied. The method proposed here allows Ks to be determined in both anisotropic and heterogeneous soils. It involves testing cubic soil cores using the Wit apparatus. To use this permeameter for samples that are not cylindrical in shape, it is necessary to prepare special measurement equipment. One such set of equipment developed consists of the soil cube (four sides of which are sealed with gypsum), which is placed in a protective box and connected to a measurement cuboid. In the soil sample, water always flows from the bottom up during the test, but it is possible to turn the sample over and thus analyze different water flow directions. The soil cubes needed are small (0.05 by 0.05 by 0.05 m), but for a particular set of conditions only 15 cores extracted from each sampling location was found to be enough to determine Ks with a precision of ±15%. Results yielded by the presented method appeared to be comparable with Ks values obtained using a constant‐head permeameter with cylindrical soil cores. The advantages of the proposed technique are the possibility of measuring Ks in both horizontal and vertical directions using the same sample, a lack of leakage along the edges of a sample, the ease of soil sample extraction, and the technique's use of inexpensive materials.
Anisotropy of saturated hydraulic conductivity (Ks, m s‐1) is a major input datum required for the modeling of saturated and unsaturated water flow in soils, significantly improving the reliability of the models. But, there are several known literature reports presenting positively verified examples of modeling of infiltration in horizontally layered small‐scale soil profiles without taking anisotropy into consideration. The objective of this paper is to analyze the influence of implementing the anisotropy ratio to the two‐dimensional mathematical model of unsaturated flow in a selected small‐scale multilayered soil profile on the possible improvement of calculations results. Two methods of soil sampling for anisotropy measurement were considered—small cylinder and cubic sampling. Our numerical model reflected the profile of a single bench terrace equipped additionally with draining sand ditch, located in Olszanka, Poland. The simple regression analysis indicated that implementing the ratio of anisotropy of saturated hydraulic conductivity to the mathematical model of variably saturated water flow in the studied horizontally layered soil profiles did not result in more precise effects of time‐variable soil moisture calculations (R2 = 0.773–0.883, P = 0.05). Moreover, results of the statistical calculations for volumetric water content and vertical flow velocity, assuming isotropic and anisotropic medium with anisotropy coefficient obtained on the basis of cylindrical and cubic samples, appeared to be comparable; the notable differences were observed only in the case of calculated horizontal flow velocity.
Abstract. The analysis of water losses should precede the decisions on repairing or modernizing a water network. Water balance and water losses indicators established by the International Water Association (IWA) standards can constitute the basis for the analysis. The methods recommended by IWA are gaining increasing popularity in many countries, including Poland. The aim of the paper is the analysis and comparison of water losses in two middle-sized water distribution systems during the period of 10 years. The compared networks are similar in respect to many parameters, including water intensity indicator value (circa 48 m 3 /d/km). Analyses were conducted on the basis of water losses indices recommended by IWA, such as Real Losses Level per connection per day (RLL), Non-Revenue Water Level (NRWL) and Infrastructure Leakage Index (ILI). The results indicated that water losses in both systems are lower than in the literature data for other similar networks.
The result of a breakage of a buried water pipe is the water movement in soil, which can cause that fine soil particles are washed out from the solid matrix and transported through pores (suffosion process IntroductionDepressions or holes creating on the soil surface as a result of suffosion can be very dangerous, especially in urban areas. It is widely known that the most hazardous phenomena of this kind relate to water-engineering structures [1,2,3]. It stems from the fact that failures and damages of pipes occur in water, sewage and storm water systems all over the world during their operation [4,5,6]. Even the high-tech methods of pipes condition assessment do not enable to prevent leakages occurrence, because of their random character and multiplicity of their reasons [7,8,9]. Still insufficient knowledge about them [10] is caused by many different, both static (pipe and soil parameters) and dynamic (hydraulic working conditions), factors [11,12,13,14,15]. Creation of suffosion holes is a phenomenon specially typical and onerous for water supply systems of a high intensity rate placed in internally unstable soils. The result of a breakage of a buried water pipe is the water movement in soil, which can cause that fine soil particles are washed out from the solid matrix and transported through pores (suffosion process) [16,17,18,19,20,21]. As a result, depressions or holes can form on the soil surface. Holes creating on the soil surface by water outflowing after a failure of a buried pipeline (suffosion holes), are in different shapes and sizes.Recognition of factors influencing holes shapes and sizes would facilitate the prevention of hazardous suffosion effects connected with failures of water distribution systems. In the range of the presented article, the influence of pressure head in a water pipe on dimensions of suffosion holes was analysed. The basis of the analysis was results of laboratory investigations of the controlled leakage from a buried water pipe.
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