Prelim Notes Flashcards
A subspecialty within the field of geotechnical engineering which deals with the design and construction of projects in order to resist the effects of earthquakes
Geotechnical Earthquake Engineering
Study of earthquakes
Seismology
Includes the study of internal behavior of the earth and the nature of seismic waves generated by the earthquake
Seismology
an individual who applies geologic data, principles, and interpretation so that geologic factors affecting the planning, design, construction, and maintenance of civil engineering works are properly recognized and utilized
Engineering geologist
In general, foundations of buildings and bridges may be divided into two major categories
shallow foundations, deep foundations
Examples of shallow foundations
spread footings, wall footings, mat foundations
Examples of deep foundations
Pile and drilled shaft foundations
To classify a soil properly, you must know its
grain-size distribution
AASHTO
American Association of State Highway and Transportation Officials
USCS
Unified Soil Classification systems
According to AASHTO Soil Classification System, soils listed in groups A-1, A-2, and A-3 are
coarse-grained materials
According to AASHTO Soil Classification System, soils listed in groups A-4, A-5, A-6, and A-7 are
fine-grained materials
According to AASHTO Soil Classification System, soils classified under A-8 like peat, muck, and other highly organic soil are identified by
visual inspection
The first step in geotechnical earthquake engineering is to perform
a screening investigation
Its purpose is to obtain sufficient information on the nature and severity of the seismic hazards so that mitigation recommendations can be developed
quantitative evaluation
The quantitative evaluation consists of the following:
Geologic mapping, Subsurface exploration, Laboratory testing, Engineering and geologic analyses, Report preparation
The required number and spacing of borings, test pits, and trenches for a particular project must be based on
judgment and experience
The main objectives of the borings, test pits, and trenches are to determine the
nature and extent of the seismic hazards
SPT
Standard Penetration Test
CPT
Cone Penetration Test
The force required to move the cone into the extended position divided by the horizontally projected area of the cone is defined as the
cone resistance qc
The _ of the soil is an important parameter needed for earthquake analyses of foundations, slopes, and retaining walls
shear strength
There are two basic types of analyses that utilize the shear strength of the soil:
(1) the total stress analysis and (2) the effective stress analysis
Under no circumstances can a total stress analysis and an effective stress analysis be _
combined
are used for the design of foundations, slopes, and retaining walls that are subjected to earthquake shaking
Total stress analyses
To perform a total stress analysis, the _ of the soil must be determined
undrained shear strength
The effective stress analysis uses the _ parameters
drained shear strength
These types of soil are nonplastic, and they include such soils as gravels, sands, and nonplastic silt, such as rock flour
Cohesionless Soil
A cohesionless soil can be held together only by a
confining pressure
These types of soil are plastic, they include such soils as silts and clays, and have the ability to be rolled and molded (hence they have a plasticity index)
Cohesive soil
internal resistance per unit area that the soil mass can offer to resist failure and sliding along any plane inside it
Shear strength
is the oldest and simplest form of shear test arrangement
direct shear test
According to this theory, the earth’s surface contains tectonic plates, also known as lithosphere plates, with each plate consisting of the crust and the more rigid part of the upper mantle.
plate tectonics
Depending on the direction of movement of the plates, there are three types of plate boundaries:
divergent boundary, convergent boundary, and transform boundary
This occurs when the relative movement of two plates is away from each other
Divergent boundary
When a divergent boundary occurs within a continent, it is called _.
rifting
This occurs when the relative movement of the two plates is toward each other
Convergent boundary
There are three types of convergent boundaries:
oceanic-continental subduction zone, oceanic-oceanic subduction zone, and continent-continent collision zone
This condition occurs when two continental plates collide with each other, causing the two masses to squeeze fold, deform, and thrust upward.
continent-continent collision zone
involves the plates sliding past each other, without the construction or destruction of the earth’s crust
Transform boundary/transform fault
a fracture or a zone of fractures in rock along which displacement has occurred
Fault
an instrument that records, as a function of time, the motion of the earth’s surface due to the seismic waves generated by the earthquake
Seismograph
a low-magnification seismograph that is specially designed to record the ground acceleration during the earthquake
Accelerograph
two basic types of seismic wave
body waves and surface waves
a seismic wave that causes a series of compressions and dilations of the materials through which it travels
P wave
fastest wave and is the first to arrive at a site
P wave
also known as the secondary wave, shear wave, or transverse wave
S wave
causes shearing deformations of the materials through which it travels
S wave
Two types of surface waves
Love and Rayleigh waves
have been described as being similar to the surface ripples produced by a rock thrown into a pond
Rayleigh waves
two basic ways to measure the strength of an earthquake
(1) based on the earthquake magnitude and (2) based on the intensity of damage
measures the amount of energy released from the earthquake
Magnitude
Based on the damage to buildings and reactions of people
Intensity
is based on the observations of damaged structures and the presence of secondary effects, such as earthquake-induced landslides, liquefaction, and ground cracking
Intensity of an earthquake
also based on the degree to which the earthquake was felt by individuals, which is determined through interviews
Intensity of an earthquake
most commonly used scale for the determination of earthquake intensity
modified Mercalli intensity scale
