Liq. channelling system partic. for ground drainage - incorporates section bringing water to porous pipe, comprising filter having characteristics determined from nature of ground

摘要

A system of channelling liq., partic. applicable to the drainage of ground contg. water, comprises a longitudinal pipe and a section, which brings the liq. to the pipe. The section includes a tubular core, made of a flexible material and able to bring the liquid to the pipe, and a filter to filter the liq. coming to the core. The core presents a helicoidal gap which extends over its length. The filter has a coefft. Mo/D50 which depends on a bridging coefft. Cb of the surrounding material and which is determined from the coordinates of a graph Cb = D90/D40. D40, D50 and D90 are the min. dimensions of the openings in given units through which particles constituting respectively 40, 50 and 90 wt.% on the dry basis of the material in which the filter material is to be used can pass. Mo is the max. dimension of the openings in the filter material expressed in the same given units. Coeffts. of the graph having Cb as ordinates and Mo/D50 as abscissae are 1.00, 2.10; 1.25, 2.60; 1.75, 3.20; 2.5, 4.15; 3.75, 5.001 7.00, 6.66; 12.50, 8,1; 25.50, 10.05. The invention resolves problems encountered with existing drainage systems and associated with the tendency of the materials used to become obstructed because of the migration of fine particles of earth into the matrix of the structures.