Geotechnical Engineering Midterm Exam 1 Flashcards

Flashcards based on the Geotechnical Engineering Midterm Exam 1 review notes.

Falling Head Permeability Test

A lab test used to determine the hydraulic conductivity of fine-grained soils.

Hydraulic Conductivity

A measure of a soil's ability to transmit water.

Compaction of Sands

Vibratory smooth drum rollers are typically best for compacting sands.

Sedimentary Rock

A type of rock formed by compaction or cementation of soil particles.

Unified Soil Classification System (USCS)

A system used to classify soils based on their particle size and plasticity characteristics.

Liquid Limit (LL)

The water content at which a soil transitions from a plastic to a liquid state; LL = 50 is the boundary between high and low plasticity clays in USCS.

Specific Gravity (Gs)

The ratio of the density of a soil solid to the density of water.

Dry Unit Weight ($\gamma_d$)

The weight of soil solids per unit total volume of soil.

Void Ratio (e)

The ratio of the volume of voids to the volume of solids in a soil.

Degree of Saturation (S)

The ratio of the volume of water to the volume of voids in a soil, expressed as a percentage.

Unified Soil Classification System (USCS) Particle Size Boundary

The boundary between sand-sized and silt-sized particles is the No. 200 sieve.

Discharge Velocity (v)

The product of the permeability (k) and the hydraulic gradient (i).

Stokes' Law Assumptions

Assumes laminar flow, no influence between particles, forces acting on a settling particle are weight, drag, and buoyancy; specific gravity is the same for all particles, and no boundary effects from the container.

Liquid Limit Definition

The water content at which a soil pat closes 1/2 inch in 25 blows.

Permeability (k)

A measure of how easily water can flow through a soil.

Constant Head Permeability Test

A lab test used to determine the permeability of coarse-grained soils.

Specific Surface Area

As the specific surface area of a clay mineral decreases, the tendency for volume change will decrease.

Darcy's Law

Describes one-dimensional flow of water through soils.

Alluvial Soil

Soil transported by streams.

Plasticity Index (PI)

PI = LL - PL, where LL is the liquid limit and PL is the plastic limit.

Liquidity Index (LI)

LI = (w - PL) / PI, where w is the moisture content.

Soil State

The condition of soil (solid, semi-solid, plastic, or liquid) based on its water content and Atterberg limits.

USCS Classification

Classification of a soil based on its liquid limit and plasticity index using the Unified Soil Classification System.

Dry Unit Weight Formula

$\gamma_d = \frac{\gamma}{1+w}$, where $\gamma$ is the moist unit weight and w is the moisture content.

Void Ratio Formula

$e = \frac{Vv}{Vs}$, where $Vv$ is the volume of voids and $Vs$ is the volume of solids.

Degree of Saturation Formula

$S = \frac{Vw}{Vv}$, where $Vw$ is the volume of water and $Vv$ is the volume of voids.

Clay Mineral with the Highest Specific Surface Area

Montmorillonite.

Degree of Saturation at Optimum Moisture Content

$S = \frac{wGs}{e}$, where w is the moisture content, $Gs$ is the specific gravity, and e is the void ratio.

Group Name of Soil (USCS)

Determined by fines content, liquid limit, and plasticity index.

Proctor Compaction Test Plot

Dry unit weight versus moisture content.

Darcy's Law States

The hydraulic gradient is the change of total head with distance.

Constant Head Permeability Test

Used for coarse-grained soils.

Weight of Soil Solids Calculation

$Ws = Gs \gammaw Vs$ where $Gs$ is specific gravity, $\gammaw$ is the unit weight of water, and $V_s$ is the volume of soil solids.

Weight of Water Calculation

$Ww = wWs$, where w is the moisture content and $W_s$ is the weight of soil solids.

Total Weight Calculation

$W = Ws + Ww$, where $Ws$ is the weight of soil solids and $Ww$ is the weight of water.

Total Volume Calculation

$V = W / \gamma$, where W is the total weight and $\gamma$ is the moist unit weight.

Volume of Air Calculation

$Va = V - Vs - Vw$, where V is total volume, $Vs$ is volume of solids, and $V_w$ is volume of water.

Void Ratio of Pond Material

Calculated from dry unit weight: $e = (Gs \gammaw / \gamma_d ) - 1$

Water Required to Raise Moisture Content

The difference in water content multiplied by the mass of solids.

Plastic Limit

The average of consistent moisture content measurements.

Coefficient of Curvature (Cc)

$Cc = \frac{(D{30})^2}{D{10} \times D{60}}$

Soil Compaction

Done to decrease the compressibility and permeability of the soil.

Hydrometer Analysis

Used for soil classification, to determine the percent of clay, and to get the grain size distribution of fine-grained soils.

Falling Head Permeability Test

Used to measure hydraulic conductivity of a clay soil specimen.

Hydraulic Gradient

$i = \frac{hA - hB}{L}$

Discharge Velocity

v = ki, where k is the coefficient of permeability and i is the hydraulic gradient.

Discharge Rate

q = vA, where v is the discharge velocity and A is the cross-sectional area.

Standard Sieve Analysis Test

The soil specimen retained in the pan consists of fines.