Design of a Knowledge-Based System for Unsaturated Soil Properties
Fredlund, Murray D.
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The Soil-Water Characteristic Curve (SWCC) is an important soil function relating the amount of water in a soil to soil suction. Many soil properties (or functions)can be related to the water content versus suction relationship of a soil. Hydraulic conductivity,shear strength, chemical diffusivity,chemical adsorption, storage, unfrozen volumetric water content, specific heat, thermal conductivity and volume change are all functions of the soil-water characteristic curve. Considerable judgment is required to enforce the relationship between soil property functions. Experts in the field of unsaturated soil mechanics provided the rules necessary in relating different soil properties.The judgment rules can be enforced by a Knowledge-Based System (KBS) design based on observations and empirical relationships among soil property functions. A design for a Knowledge-Based System was developed using a relational database management system (RDBMS) known as Microsoft's Access® database program. The design provides an estimate of the soil-water characteristic curve as well as a wide variety of unsaturated soil property functions from basic soil classification data. The accuracy of the design was tested using the Access®and the output of the prediction functions was verified using MathCad®. Applications of the Knowledge-based System were also illustrated to demonstrate the power and flexibility of such a system. The design should reduce both time and costs associated with obtaining the soil properties for numerical modelling.