Avaliação de sistemas drenantes alternativos na drenagem subterrânea.

Abstract

The purpose of this research was to evaluate the hydraulic performance of different subsurface drainage systems under laboratory controlled conditions, using a sand tank horizontal physical model. The drainage systems were composed by the following materials: smooth PVC pipe for sewage, with nominal diameter of 50.0 mm and opened area of 23,0 cm2.m"'; Drenoflex corrugated flexible PVC pipe, with nominal diameter of 65,0 mm and opened area of 23,0 cm2.m"K, Kananet corrugated flexible polyethylene pipe of high density from the Kanaflex, with nominal diameter of 75,0 mm and opened area of 110,0 cm2.m_ 1; and the envelopes made of OP-20 bidim polyester synthetic blanket, zero crush, and foam polyurethane synthetic blanket, with 5,0 mm of thickness. The factorial statistical arrangement was used, where the nine treatments with three repetitions each, involved all combinations between drainage pipe and envelope. The evaluation of the drainage systems performance was based on typical parameters proposed in the literature. Respecting to inlet hydraulic head, all drainage systems were classified as regular. Considering the ratio between the inlet and total hydraulic head, the obtained results weren't satisfactory. Regarding the entrance resistance, it was verified significant difference for all drainage systems. The smooth PVC pipe presented larger entrance resistance with the foam envelope. Also, it was verified that the smaller values for the entrance resistance were obtained with the use of zero crush envelope, followed by the foam envelope in the conventional pipes. A l l drainage systems were classified good to very good. Regarding the outflow, it was verified that all drainage pipes with bidim and zero crush envelopes didnt presented difference. The Drenoflex and Kananet conventional drainage pipes didn't differ with the foam envelope use. For all drainage systems, the highest and lowest discharges were fund with the use of zero crush and bidim envelopes, respectively. In the evaluation regarding the entrance resistance factor, all drainage systems presented values between the limits established in the literature, being considered as very good.