Fe Civil Geotechnical Engineering

Front 1

What two types of soil samples are typically obtained during a site investigation?

Back 1

Disturbed and undisturbed, which are also known as "relatively" undisturbed or in-situ, soil samples are collected during this kind of investiagation

Front 2

What is the name of a pipe-shaped rod or tube with helical flanges that is drilled into the ground?

Back 2

An auger, which is also known as auger stem or auger flights, can bet these shapes and may be either solid or hollow

Front 3

What type of in-situ test method has the units "blows per foot"?

Back 3

The Standard Penetration Test (SPT) uses a known amount of energy to drive a standardized sampler into in-situ soils and is expressed in these units

Front 4

In what soil classification system are fine-grained soils and course-grained soils separated by 50% passing the no. 200 sieve?

Back 4

The Unified Soil Classification System (USCS) separates these two soil types because the fine-grained soil sample exceeds 50% passing the no. 200 sieve

Front 5

In the AASHTO Soil Classification System, granular materials are separated by silt-clay materials by what percent passing the no. 200 sieve?

Back 5

This soil classification method separates silt-clay materials from granular materials by greater than 35% passing the no. 200 sieve, which is different thant the USCS.

Front 6

In USCS, what symbol is required if the percent passing the no. 200 sieve results in a value between 5% and 12%?

Back 6

A dual symbol, such as GW-GC, is used when the percent passing the no. 200 sieve meets this criteria

Front 7

What is the record that contains sample elevation, SPT blow count values, lab test findings, and graphical methodology for presenting subsurface soil conditions called?

Back 7

A boring log or test boring record should contain boring location, date of drilling, ground surface elevation, subsurface descriptions as well as these graphics and findings

Front 8

What is the common method for presenting SPT results in a boring log?

Back 8

These results are commonly presented as sets of 6-inch increments per sampling location. When refusal to the sampler is encountered, there may be fewer data sets. However, the number presented is typically per 6-inch increment.

Front 9

What symbol represents the depth of groundwater in a boring log?

Back 9

A triangle pointing downward at the appropriate elevation represents this in a boring log.

Front 10

What is a characteristic of clay that is used for classification between “low” and “high”?

Back 10

This characteristic is known as plasticity.

Front 11

What two types of soil are granular and cohesionless?

Back 11

Sand and gravel share these characteristics.

Front 12

What two types of soil can be described as soft or stiff?

Back 12

These terms are used to describe the consistency of silt and clay.

Front 13

What are index properties?

Back 13

This term refers to the characteristics of a soil that are used to classify it and include grain size distribution, plasticity, and fines fraction.

Front 14

What are Atterberg limit tests?

Back 14

These tests determine the levels of moisture content at which a soil behaves like a solid, a semi-solid, a plastic solid, and a liquid.

Front 15

What is a sieve analysis?

Back 15

During this test a soil sample is sifted through a series (or nest) of screened sieves. This test yields the distribution of grain sizes in the soil, which is important for soil classification.

Front 16

What is a phase diagram?

Back 16

This kind of diagram shows the mass and volume of the three constituents of a soil: solids, air, and water.

Front 17

What is moisture, or water, content?

Back 17

This is the ratio of the mass of water to the mass of the solids portion of a soil sample, and is expressed as a percentage.

Front 18

What is dry density or dry unit weight?

Back 18

This is the ratio of the mass of dry solids to the total volume of a soil sample.

Front 19

What is the degree of saturation?

Back 19

This is the ratio of the volume of water to the volume of void space in a soil sample, and is expressed as a percentage.

Front 20

What is permeability?

Back 20

This is the measure of how well fluids flow through pore spaces in a soil matrix.

Front 21

What is a falling-head permeability test?

Back 21

During this test, water or another fluid is made to flow through soil as the change in elevation head is recorded.

Front 22

What is a constant-head permeability test?

Back 22

During this test, water or another fluid is made to flow through soil with the elevation head kept at a steady level as the quantity of water leaving the soil is recorded.

Front 23

What is a direct shear test?

Back 23

During this test, a normal compressive stress is applied to a soil specimen and the amount of stress needed to perpendicularly shear the specimen is measured.

Front 24

What is a triaxial stress test?

Back 24

During this test, a soil specimen is subjected to increasing compressive stress until the specimen fails. The principle stress distribution can then be evaluated to find the soil’s shear strength.

Front 25

What is Boussinesq’s equation used for?

Back 25

This equation is used for calculating how pressure is distributed beneath footings with relatively small widths.

Front 26

What does the 60° method estimate?

Back 26

This method is commonly used to estimate the zone of influence below an area of applied load.

Front 27

When is earth pressure considered to be lateral?

Back 27

When earth pressure is exerted horizontally by a soil on a vertical surface, such as a retaining wall, that is expressed in force per unit of area.

Front 28

What is the Rankine earth pressure theory?

Back 28

This methodology is used to determine the lateral earth pressure on a retaining wall with a vertical, non-inclined face. It assumes negligible friction between the wall and the soil.

Front 29

What is the Coulomb earth pressure theory?

Back 29

This methodology is used to determine the lateral earth pressure on a retaining wall that may be inclined. It accounts for friction between the wall and the soil.

Front 30

What is pore pressure?

Back 30

This is the fluid pressure that develops in the void spaces of a saturated soil under hydrostatic conditions. It is also known as neutral stress because the pressure acts equally in all directions.

Front 31

What law is used to calculate the coefficient of permeability for a soil or aquifer?

Back 31

Darcy’s law is used to calculate this value.

Front 32

What is the “total stress” of a point within a soil mass at depth?

Back 32

This is the body pressure developed at a point in a mass of soil due to the density or unit weight of the soil above that point. It includes pore pressure from water in the soil but ignores any effect from air in the void spaces.

Front 33

What is the “effective stress” of a point within a soil mass at depth?

Back 33

This is the portion of the total stress supported by contact among the particles in a soil matrix. It equals total stress less pore pressure. It is also called the intergranular stress.

Front 34

What is consolidation of a soil?

Back 34

This is the result of compression of a soil by an applied load. When this process occurs, the void spaces in a soil shrink and the intergranular contact pressure effective stress increases.

Front 35

What is normal consolidation of a soil?

Back 35

This type of consolidation is when a soil’s pressure and stress state are both higher than they have ever been.

Front 36

What is overconsolidation of a soil?

Back 36

This type of consolidation is when a soil’s pressure and stress state are both less than they have been in the past.

Front 37

What is compaction?

Back 37

This process often uses heavy equipment with steel rollers to reduce void volume and push out air. It increases the strength, stability, and support capacity of a soil.

Front 38

What is the Proctor test?

Back 38

This test, which is also called a moisture-density relationship test, determines the combination of dry soil and moisture that will achieve the highest density for a soil.

Front 39

What is slope stability?

Back 39

This is the ability of a slope of soil to maintain its shape and not fail. This quality is measured by analysis of the soil’s internal friction strength and cohesion.

Front 40

What is a flow net?

Back 40

This is a graphic representation of the seepage of water or another fluid through a porous media typically below the surface of the ground. It shows streamlines (paths of seepage) and equipotential lines, which are contour lines of constant hydrostatic pressure.

Front 41

What is a foundation?

Back 41

This is a substructure designed to support a superstructure. Its design will vary, depending on soil characteristics and groundwater conditions.

Front 42

What is general bearing capacity?

Back 42

This is the capacity of a soil to provide vertical support without shear failure or movement that could damage a structure.

Front 43

What is ultimate bearing capacity?

Back 43

This is the capacity of a soil to provide vertical support up to a maximum pressure. The maximum pressure can be predicted from the shape and depth of the foundation, groundwater, and soil properties such as density, angle of internal friction, and cohesion.

Front 44

When is the Terzaghi-Meyerhof equation used?

Back 44

This equation gives the ultimate bearing capacity for a continuous footing or wall footing.

Front 45

What is allowable bearing pressure?

Back 45

This is the pressure that can safely be placed on a soil mass without the expectation of failure or movement. A factor of safety is applied when determining this amount.

Front 46

What are the bearing capacity factors?

Back 46

These factors are the variables Nγ, Nc, and Nq, which are used in the Terzaghi-Meyerhof equation. Their values are determined from the angle of internal friction.

Front 47

What are shape factors?

Back 47

These factors are corrections applied to the Terzaghi-Meyerhof equation for various shapes other than continuous footings.

Front 48

What is actual bearing pressure?

Back 48

This is the real pressure a footing applies on a soil mass. It can be used in designing a new footing or in evaluating the factor of safety for an existing footing by comparing it to allowable bearing capacity.

Front 49

What is primary consolidation?

Back 49

This is the gradual compression of a layer of saturated clayey soil during which water is squeezed out of voids.

Front 50

What is settlement (or settling)?

Back 50

This is the consolidation of a layer of soil at depth that causes the soil layers above that point up to the ground surface to sink.

Front 51

What is the compression (or compressibility) index?

Back 51

This value, Cc, is the slope of the normally consolidated portion of a test curve graphed on a semilogarithmic plot. It is used to calculate the magnitude of settlement.

Front 52

What is the coefficient of consolidation?

Back 52

This quantity, Cv, represents the material properties of a soil that have an effect on the speed of consolidation, such as permeability and void ratio. It is typically given in units of ft2/day or m2/day.

Front 53

What is a mat foundation?

Back 53

This is an oversized footing that may lie under the entire area of a building, or be used under a tower to give resistance to overturning.

Front 54

What is a raft foundation?

Back 54

This is a very large footing used to reduce differential settlement. It is often designed to displace a large volume of soil and give a larger overall bearing capacity than that of smaller footings.

Front 55

What is a gravity wall?

Back 55

This is a large buttress or bulk of concrete constructed to provide weight over the heel of a retaining wall. It increases resistance to overturning from lateral earth pressure.

Front 56

What is earth pressure?

Back 56

This is a force per unit of area exerted by soil on a retaining wall, and is usually understood to be horizontal. It may be active or passive.

Front 57

What is the earth pressure resultant?

Back 57

This force is derived from an earth pressure condition and acts at the centroid of the pressure distribution area. It is used to determine the overturning forces on a retaining wall.

Front 58

What is a cantilever wall?

Back 58

This kind of wall is supported by a continuous footing, and is constructed to resist overturning due to the soil backfill weight placed over the toe and heel.

Front 59

What is “active” earth pressure?

Back 59

This is a force per unit of area exerted by a retaining wall moving away from a soil mass. It is typically associated with a reduction in horizontal confinement.

Front 60

What is “at-rest” pressure?

Back 60

This is a force per unit of area that occurs naturally in a soil mass when there is no retaining wall or when a retaining wall is completely constrained from moving.

Front 61

What is “passive” earth pressure?

Back 61

This type of pressure is exerted by a retaining wall moving toward a soil mass.

Front 62

What does Rankine earth pressure theory assume?

Back 62

This theory assumes that soil failure occurs on a plane extending behind the retaining wall at a specific angle from horizontal.

Front 63

What does Coulomb earth pressure theory assume?

Back 63

This theory assumes that soil failure occurs on a flat plane at a specific angle from horizontal, and also accounts for the friction between the retaining wall, soil, and backfill faces.

Front 64

What is a mechanically stabilized wall?

Back 64

This is a retaining wall that is supported by bracing, shoring, struts, tie rods, or metal strips that extend into the backfill. It resists overturning and is supported above the footing to resist horizontal earth pressure.

Front 65

What is the Tschebotarioff pressure distribution?

Back 65

This is a method for analyzing pressure distributions on braced cuts that are supported by struts. It assumes the pressure distribution is trapezoidal and provides expected lateral pressure values.

Front 66

What is sheet piling?

Back 66

This is used to brace an open excavation site that is constructed prior to digging. It typically consists of interlocking steel structures driven into place, which act as a continuous wall.

Front 67

What is an anchored bulkhead?

Back 67

This structure is supported by a tie rod that extends into the backfill soils. The tie-rod anchor resists overturning by transferring horizontal earth pressure acting on the backfill face into the passive pressure region of the soil mass behind the failure zone or slip plane.

Front 68

What is the inflection point of an anchored bulkhead?

Back 68

This point on an anchored bulkhead is where the active pressure balances the passive pressure. At this point, there is zero shear and maximum moment.

Front 69

What is the critical height of excavation?

Back 69

This is the where heaving of the soils will start to occur. It is dependent on distance to subsurface hard layers beneath the excavation.

Front 70

What is anchor pull?

Back 70

This is the quantity of tension in a tie rod or anchor. It is found by analyzing the static moment around the hinge point.

Front 71

What is a seismometer?

Back 71

This is an instrument used to measure energy or seismic waves moving through Earth’s crust. It is used primarily to detect earthquakes.

Front 72

What are faults?

Back 72

These are fractures in Earth’s crust where opposing portions can move relative to each other. Slips along these can release enough energy to be felt miles away.

Front 73

What is an epicenter?

Back 73

This is the location on the ground surface directly above the focus of energy release. It is directly above the hypocenter and is used to report an earthquake’s location.

Front 74

What is Richter magnitude?

Back 74

This is based on the logarithm of the amplitude recorded by a seismometer. It is reported in whole numbers and decimals. Because it is logarithmic, the difference between two whole number values is a ten-fold increase.

Front 75

What is peak ground acceleration?

Back 75

This is the maximum acceleration of the ground during an earthquake. Typically, it is used for design parameters that are regulated by building code provisions.

Front 76

What is site period?

Back 76

This is the inverse of the natural frequency of a site. If the site has a natural frequency that corresponds to the frequency of the seismic waves during an earthquake, serious damage can occur.

Front 77

What is spectral acceleration?

Back 77

This is the maximum acceleration that is experienced by a single degree-of-freedom vibratory system. It provides a method for applying the ground acceleration and site period to determine levels of building damage.

Front 78

What is base shear?

Back 78

This is the theoretical maximum seismic force that acts on a structure at the ground. It is determined from spectral acceleration.

Front 79

What is liquefaction?

Back 79

This is the condition that occurs in saturated soils where the shear strength of the soil is suddenly reduced to zero by escalating pore pressure due to seismic shaking.

Front 80

What is a cyclic stress ratio?

Back 80

This is the quantity used to rate the potential for liquefaction in sands up to depths of 40 feet. It is calculated by dividing the average cyclic shear stress by the initial vertical effective stress acting on the sand layer prior to a seismic event.

Front 81

What is a cyclic resistance ratio?

Back 81

This is used to indicate the potential for liquefaction. It is calculated from the tip resistance portion of data obtained from a cone penetration test (CPT).

Front 82

What is volumetric strain?

Back 82

This occurs in a layer of soil due to stress application or liquefaction. It is typically expressed as a percentage and can be applied to a layer thickness to determine settlement.

Front 83

What is a response spectrum?

Back 83

This represents the maximum response of a single degree of freedom, linearly elastic harmonic oscillator subjected to a series of earthquake ground motions.

Front 84

What is axial capacity?

Back 84

This is the capacity of a pile to carry a vertical load. Piles are elements of a deep foundation system that are hammered or drilled into the soil.

Front 85

What is side friction?

Back 85

This is a portion of axial capacity that results from a pile’s resistance to sliding in a soil mass. It is also called friction capacity or skin friction.

Front 86

What is end-bearing?

Back 86

This is a portion of axial capacity obtained from tip resistance of a pile in dense soils. It is obtained when the tip area is supported by the underlying strata.

Front 87

What is ultimate static bearing capacity?

Back 87

This is an ultimate axial capacity that is the sum of the end-bearing and side friction for a pile.

Front 88

What is safe load (or driven capacity)?

Back 88

This is obtained empirically from pile driving calculations. Common pile driving equations are used to determine the allowable vertical load from hammer energy, driving weight, and average distance per hammer blow.

Front 89

What is a skin friction coefficient?

Back 89

This is a value determined for friction capacity based on the evaluation of shear strength and resistance to sliding in the soil mass. It is determined from soil cohesion and friction properties of the soil mass on the pile material.

Front 90

What is lateral capacity?

Back 90

This is the capacity of a pile to resist movement in a horizontal direction.

Front 91

What is a modulus of subgrade reaction?

Back 91

This is a value that represents the quantity of soil deflection due to a horizontal pressure imposed by a pile. It is used to determine the amount of soil deflection that occurs at a point along the pile installation depth due to horizontal pressure from lateral loading.

Front 92

What is lateral deflection?

Back 92

This is displacement of the pile in a direction perpendicular to its axis. It is determined using the modulus of subgrade reaction for the soil and the quantity of resulting lateral pressure.

Front 93

What is the adhesion factor?

Back 93

This quantity, α, is the ratio of a soil’s cohesion to its adhesion, or its capacity to adhere to the pile surface and cause shear resistance due to sliding. The α-method uses this value to modify the cohesion value in order to determine the skin friction.

Front 94

What is the skin friction factor?

Back 94

This quantity, β, is determined from the length of a pile that passes through a clay layer. In the β-method, this value is multiplied by the average effective stress of the layer of clay where the pile exists in order to determine a side friction value.

Front 95

What is tensile (or uplift) capacity?

Back 95

This is the capacity of a pile to resist being pulled out of the ground. This quality is important where a pile is part of a group connected by a cap. A rotation may occur in the cap that the pile must be designed to resist.

Front 96

What is pile group action?

Back 96

This is when the capacity of a pile system is influenced by the piles collectively rather than individually.

Front 97

What is downdrag?

Back 97

This results from consolidation of a soil mass causing negative, or downward, skin friction that overcomes the downward movement of the pile.

Front 98

What is a pile load test?

Back 98

This is the methodology where a vertical or horizontal load is applied to a pile and the resulting deflection is recorded.

Front 99

What is frost jacking (or adfreeze force)?

Back 99

This condition occurs where a pile moves upward in relation to the ground as freezing occurs.