Important Terms in Geo Technical Engineering (Soil mechanics)

Important Terms in Geo Technical Engineering (Soil mechanics)

Important Terms in Geo Technical Engineering (Soil mechanics) Void Ratio The void ratio of a mixture is the ratio of the volume of voids to volume of solids. The amount of void present in the soil mass. Porosity The space between particles is called pore space. a soil has. The porosity of a soil is expressed as a percentage of the total volume of the soil material. Degree of Saturation The degree of saturation is the ratio of the volume of water to the volume of voids. It is denoted by 'S'. The degree of saturation generally expressed as a percentage. It is equal to zero when the soil is absolutely dry and 100% when the soil is fully saturated. Specific Gravity It also called relative density is the ratio of the density of a substance to the density of a reference substance; equivalently, it is the ratio of the mass of a substance to the mass of a reference substance for the same given volume. Unit Weight of Soil Unit weight of the soil is the total weight of the soil divided by total volume. Total weight of soil also includes weight of water. Seepage velocity Seepage velocity is the velocity of groundwater calculated from Darcy's law. Seepage velocity is not the actual velocity of the water in the pores, but the apparent velocity through the bulk of the porous medium. Discharge Velocity Discharge velocity is the volume of water flowing in unit time across the unit cross section perpendicular to the direction of flow. Seepage flow is the volume of of water flowing in unit time across the unit surface area of available voids Flow net A flow net is a graphical representation of two-dimensional steady-state groundwater flow through aquifers. Construction of a flow net is often used for solving groundwater flow problems where the geometry makes analytical solutions impractical. Moisture content Moisture content is the amount of moisture in the sample given as a percentage of the sample's original (wet) weight. Dry content is the amount of solids which are left after drying given as a percentage of the sample's original (wet) weight. Liquid limit It is the minimum water content the soil still act as liquid and it has some shearing resistance to flow. The water content the soil is change liquid limit to plastic limit is called liquid limit Plastic Limit Plastic limit is the water content in clay soil below Which it stops to behave like a plastic material. it starts to crumble when rolled in threads of 3 mm diameter Shrinkage limit It is the minimum water content the reduction in water in soil does not make any volume change is called shrinkage limit. The shrinkage limit is the water content at which the volume of the soil starts to increase. It is also at the point where the soil is 100% saturated. Angle of internal friction Angle of internal friction (friction angle) A measure of the ability of a unit of rock or soil to withstand a shear stress. It is the angle (φ), measured between the normal force (N) and resultant force (R), that is attained when failure just occurs in response to a shearing stress (S) Specific area Specific surface area (SSA) is a property of solids defined as the total surface area of a material per unit of mass, (with units of m2/kg or m2/g) or solid or bulk volume (units of m2/m3 or m−1). It is a physical value that can be used to determine the type and properties of a material Liquefaction Liquefaction is a phenomenon in which the strength and stiffness of a soil is reduced by earthquake shaking or other rapid loading. Liquefaction and related phenomena have been responsible for tremendous amounts of damage in historical earthquakes around the world