Desempenho de drenos ranhurados sem material envoltório

Abstract

The performance and durability of subsurface drainage systems are associated with their ability to facilitate water flow while restricting sediment entry, preventing blockages that compromise discharge capacity and system performance. To mitigate this issue, the use of envelope is common, however, these materials increase system costs, complicate drainpipe installation, are susceptible to clogging, and may promote soil erosion by water. In this context, drainage pipes with perforations designed to reduce solid particle transport and eliminate the need for envelope materials, such as knife-cut drainpipes, emerge as a cost-effective and practical alternative. However, their adoption remains limited, primarily due to the lack of studies demonstrating their effectiveness under different soil and climatic conditions. The objective of this study was to evaluate and compare the water intake capacity, discharge rates, and solid transport rates between drainpipes with smaller perforation in a knife-cut design (KC drainpipe), considered non-conventional, and drainpipes with larger and rounded perforations, considered conventional, under conditions with and without envelope material. To achieve this, the perforations of each drainpipe were characterized, and two experimental setups were developed: one to evaluate the drainage capacity of the drainpipes under varying hydraulic head, and another to measure discharge and solid transport rates across different porous media. The results indicated that the conventional drainpipe, due to the larger perforations opening area, exhibited lower entrance resistance and a larger effective radius compared to the knife-cut drain, which has smaller perforations. The orifice equation effectively represented the behavior of both conventional and knife-cut drainpipes but required simultaneous fitting to the discharge coefficient and head exponent for drainpipes with envelope material. Drainpipes with larger perforations increased the discharge rate but also facilitated sediment transport, thereby increasing the risk of clogging. Drainage efficiency is influenced by the properties of porous media, with fine-textured soils hindering drainage due to their high-water retention capacity, while coarse-textured soils facilitate water flow but are more prone to particle transport. Although envelope materials facilitate water inflow, their efficiency may be reduced by clogging, particularly in low-cohesion soils. Knife-cut drainpipes, despite having a lower discharge capacity, offer a more stable and controlled flow, promoting prolonged drainage. Their solid transport rates are comparable to those of conventional drainpipes with envelopes, making them a more economical and easier-to-install solution.