| Summary: | A simplified numerical model has been developed with the aim of predicting the water content in multilayer systems, such as railway or road sections, from some basic properties of the materials, the geometry and a variable rainfall intensity.
This type of tool is built with the aim of increasing computational speed at the expense of accuracy, which could be used in applications that require a high number of computations, such as maintenance tools based on predictive management, risk management sensitivity analysis or probabilistic calculations.
The model will be able to predict the evolution of the water content in each layer using only the basic properties of the materials involved.
To this end, several predictive expressions and methods have been formulated to predict water retention curves and saturated permeability in any type of material, including clays, silts, sands, gravels or any combination of these.
Particular emphasis has been placed on the analysis of the hydraulic properties of clean and fouled ballast, due to the need to account for special circumstances such as gravity, turbulence or permeability degradation due to progressive fouling.
The expressions and methods for estimating the hydraulic properties have been validated by several tests from the literature with satisfactory results, and the simplified model for predicting the moisture content has been compared with an equivalent physical test where a layer of ballast and sub-ballast is subjected to a variable rainfall inflow, and the results discussed.
Although future work and research is required to make this tool functional for practical use, this research proves the viability of this type of analysis for such applications.
The expressions and methods for estimating hydraulic properties are not only applicable to the simplified model, but could be applied to any study requiring the estimation of the water retention curve and saturated permeability from basic soil properties such as grain size distribution, plasticity and porosity of the soil.
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