Geocomposite Drain Flow
Calculate the drainage flow of a drainage geocomposite, q = θ·i·b, from the transmissivity θ (m²/s), the hydraulic gradient i (dimensionless) and the drain width b (m). This is the practical application of transmissivity: it estimates how much water a drainage geocomposite (geonet between geotextiles, or drainage geotextile) can convey in its plane, to check whether it adequately replaces a gravel layer or conventional drain. The flow is the product of transmissivity (the drain's in-plane 'conductivity' at the work's confining pressure), the hydraulic gradient (the head-line slope driving the flow) and the drain width (the drainage front). It is Darcy's law applied to in-plane flow in the geosynthetic. This calculation is essential to size drainage systems with geocomposites: gas and liquid drainage in landfills and mining, drains behind walls and cutoffs, green-roof and buried-structure drainage, and road and railway drains. The flow the geocomposite provides is compared with the design flow (the water to drain, with a safety factor); if insufficient, a higher-transmissivity geocomposite is chosen or the width increased. Enter the transmissivity, hydraulic gradient and width.
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Vazão de dreno geocomposto
A vazão de drenagem de um geocomposto drenante é q = θ·i·b, a partir da transmissividade θ, do gradiente hidráulico i e da largura do dreno b. Esta é a aplicação prática da transmissividade: estima quanta água um geocomposto drenante (georrede entre geotêxteis, ou geotêxtil drenante) consegue conduzir em seu plano, para verificar se ele substitui adequadamente uma camada de brita ou um dreno convencional. A vazão é o produto da transmissividade (a 'condutividade' do dreno no plano, na pressão de confinamento da obra) pelo gradiente hidráulico (a inclinação da linha de carga que impulsiona o fluxo) e pela largura do dreno (a frente de drenagem). É a Lei de Darcy aplicada ao escoamento no plano do geossintético. Esse cálculo é essencial para dimensionar sistemas de drenagem com geocompostos: drenagem de gases e líquidos em aterros sanitários e mineração, drenos atrás de muros e cortinas, drenagem de coberturas verdes e estruturas enterradas, e drenos de estradas e ferrovias. Compara-se a vazão que o geocomposto fornece com a vazão de projeto (a água a ser drenada, com fator de segurança); se insuficiente, escolhe-se um geocomposto de maior transmissividade ou aumenta-se a largura. Informe a transmissividade, o gradiente hidráulico e a largura.
Related Tools
Geotextile Transmissivity
Calculate a geosynthetic's transmissivity, θ = k_p·t, from the in-plane permeability k_p (m/s) and the thickness t (m); the result, in m²/s, is the transmissivity. Transmissivity characterizes the geosynthetic's ability to convey water WITHIN its own plane (longitudinally, like a planar drain), and is the key property in the DRAINAGE function. While permittivity measures flow THROUGH the geotextile (perpendicular), transmissivity measures flow ALONG it (parallel). It is the fundamental property of drainage geocomposites and geonets — products with a 3D open core (geonet) between filtering geotextiles, used to drain water replacing gravel layers: drainage behind retaining walls, under landfills (leachate and gas collection), in roads, sports fields and gardens (subsurface drainage), and in foundations. Transmissivity depends strongly on confining PRESSURE (the more compressed, the less space for water to flow and the lower θ) and on gradient, so it is specified at the work's real load conditions. Times the gradient and width, it gives the drained flow. Enter the in-plane permeability and the thickness.
Geotextile Permittivity
Calculate a geotextile's permittivity, ψ = k_n ÷ t, from the cross-plane permeability k_n (m/s) and the geotextile thickness t (m); the result, in s⁻¹, is the permittivity. Permittivity characterizes the geotextile's ability to let water pass PERPENDICULAR to its plane (through the fabric), and is the key property in the FILTRATION and cross-plane DRAINAGE functions. It is defined as permittivity (not simply permeability) because a geotextile's thickness is small, variable and hard to measure precisely under load — so permeability is normalized by thickness, giving a property (ψ = k/t) measurable directly from flow per unit area and gradient, without knowing the thickness. In a geotextile filter (replacing the traditional graded sand filter in drains, behind retaining walls, under riprap), the geotextile must be permittive enough to let water pass freely (without damming and building pore pressure), but with pores small enough to RETAIN the soil particles (without clogging or letting soil escape — the retention criterion). The balance between permittivity and retention is the heart of geotextile filter design. Enter the cross-plane permeability and the thickness.
Solids Mass Flow (Dredge)
Calculate the mass flow of solids transported by a dredge or pipeline, ṁ_s = Q·C_v·ρ_s, from the total slurry flow Q (m³/s), the solids volumetric concentration C_v (fraction) and the solids density ρ_s (kg/m³). Solids mass flow is the MASS of useful material transported per unit time (kg/s, or tonnes per hour), the production indicator used when TONNAGE matters — the typical case of ore transport by pipeline (measured in t/h of dry ore) and mineral processing. It is the product of three factors: the slurry flow (pump capacity), the solids concentration (how 'loaded' the slurry is) and the solids density (iron ores, for example, are very dense, ~5000 kg/m³, so little volumetric concentration already gives high tonnage). Mass flow, integrated over time, gives the total transported tonnage, the basis of billing and operational mass balance. Optimizing it — maximizing tonnage per unit pumping energy — is the central goal of pipeline operation, which moves hundreds of millions of tonnes of ore per year over long distances far more energy-efficiently than trucks or trains. Enter the slurry flow, the volumetric concentration and the solids density.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.