chapter 5 Flashcards
(142 cards)
1
Q
These are techniques used to study
the Earth’s surface and subsurface to find
natural resources, assess environmental conditions, and understand geological structures.
A
Geological methods
2
Q
Classification of Geological Methods
A
- Surface Exploration
- Subsurface Exploration
3
Q
This involves studying the Earth’s surface to gather geological data using non-intrusive
techniques.
A
Surface exploration
4
Q
This is a method of collecting geomatics or other imagery by using airplanes, helicopters, UAVs, drones or other aerial methods.
A
Aerial survey
5
Q
This is the study of aerial photographs and satellite images to analyze landforms,
rock types, and geological structures without physical contact with the site.
A
Photogeology
6
Q
This is an investigation of the hydrologic and geologic parameters at the subsurface level in a particular area.
A
Hydrogeological survey
7
Q
This focuses on investigating what lies beneath the Earth’s surface to better understand underground geological formations.
A
Subsurface exploration
8
Q
Subsurface exploration are accomplished by following two broad methods:
A
- Direct Method
- Indirect Method
9
Q
Involves physical techniques such as digging, drilling boreholes, and collecting core samples to analyze underground rock and soil layers.
A
Direct Methods
10
Q
Involves the use of geophysical techniques, such as seismic waves, ground penetrating radar, and magnetic surveys, to detect underground structures without physical excavation.
A
Indirect Methods
11
Q
This is the process of the collection of information, the appraisal of data, assessment, and reporting without which the hazards in the ground beneath the site cannot be known.
A
Site investigation
12
Q
The reason for a site investigation is to understand the following:
A
- The composition of soil layers and bedrock
- Groundwater conditions
- Durability, compressibility, and strength of soil, rocks, soil strata
- Chemical composition of groundwater on site
- Composition of foundations on nearby site
13
Q
Background Information before Subsurface Investigation
A
- The type of structure to be built, its intended use;
- Characteristics of the structure;
- Starting date;
- Intended construction method;
- The estimated period of construction;
- The probable soil condition at the site, by geological, geotechnical or aerial analysis;
- The behavior of existing structures adjacent to the site, as well as other facts available through local experience.
14
Q
It is the process of searching for evidence of any mineralization hosted in the surrounding rocks.
A
Exploration
15
Q
It is the process of finding commercially viable mineral resource and the objective is to locate it in the shortest possible time and at the lowest possible cost.
A
Exploration
16
Q
It usually begins with low impact operations, including desktop testing and field inspections, to assess if signs of minerals or petroleum are present. It is achieved before more intensive and expensive technologies such as geochemical sampling, exploration and geophysical surveys are carried out.
A
Exploration
17
Q
Exploration Techniques
A
- Geophysical Surveys
- Geological Mapping
- Geochemical Survey
18
Q
These include the implementation of geophysical methods to indirectly determine the geological and structural as well as the physical and mechanical characteristics of the foundation soil. These methods are used to determine the layout, thickness and properties of individual layers below the terrain surface, on which the construction of a specific structure is planned.
A
Geophysical surveys
19
Q
Types of Geophysical Survey
A
- Airborne Geophysical Survey
- Gravity Surveys
- Seismic Surveys
- Magnetic Geophysical Survey
- Radiometric Geophysical Surveys
- Electromagnetic (EM) Surveys
- Induced Polarization (IP) Survey
- Drillhole Surveys
20
Q
This is the process of locating and identifying rock types and geological structures in relation to landforms and topography, it is sometimes the first method of exploration used on the ground, and it may take place at a local comprehensive scale or a regional scale.
A
Geological mapping
21
Q
This creates a geological map of the exploration region, which will show the distribution of rock types and structures.
A
Geological mapping
22
Q
These are used to identify areas for further investigation. Soil, rock and/or sediment samples are typically collected as part of the surveys. These samples are sent to a laboratory for analysis in order to determine prospective mineralization zones.
A
Geochemical surveys
23
Q
Types of Geochemical Surveys
A
- Soil Sampling
- Rock Chip Sampling
- Costeaning (Trench Sampling)
- Stream Sediment Sampling
- Channel Sampling
- Bulk Sampling
24
Q
These are non-invasive techniques used to investigate subsurface properties and structures.
A
Geophysical Methods
25
These rely on measuring and analyzing physical properties such as electrical, magnetic, gravitational, and seismic characteristics to provide information about the subsurface.
Geophysical Methods
26
Geophysical Methods
1. Ground Penetrating Radar (GPR)
2. Electrical Resistivity Tomography (ERT)
3. Magnetometry
4. Gravity Surveys
5. Seismic Methods
27
This uses electromagnetic waves to image subsurface features. It emits high-frequency radio waves into the ground and detects the reflections caused by variations in subsurface materials.
Ground Penetrating Radar (GPR)
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This is effective in locating buried utilities, detecting voids, mapping bedrock, and determining changes in soil stratigraphy.
Ground Penetrating Radar (GPR)
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This measures the electrical resistivity of subsurface materials. By injecting electrical current into the ground and measuring the resulting voltage, engineers can determine variations in resistivity.
Electrical Resistivity Tomography (ERT)
30
This is useful in mapping subsurface structures, detecting groundwater levels, and identifying contamination plumes.
Electrical Resistivity Tomography (ERT)
31
This measures variations in the Earth's magnetic field caused by subsurface materials with different magnetic properties.
Magnetometry
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By using these, engineers can identify buried ferrous objects, archaeological features, and subsurface structures.
magnetometers
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This is particularly valuable in archaeological surveys and identifying buried metallic utilities.
Magnetometry
34
These measure variations in the Earth's gravitational field caused by differences in subsurface density.
Gravity surveys
35
These are commonly used in geotechnical investigations and mineral exploration.
Gravity surveys
36
By recording the gravitational acceleration at various points on the surface, engineers can infer the presence of subsurface features such as _________, __________, and _____________.
faults, basements, and density variations
37
These involve generating and recording seismic waves to study subsurface structures.
Seismic methods
38
The two primary seismic techniques used in civil engineering are:
Seismic Reflection
Seismic Refraction
39
This method utilizes controlled sources of energy, such as hammer strikes or explosives, to generate seismic waves.
The waves reflect off subsurface interfaces and are recorded by receivers (geophones).
Seismic Reflection
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This is effective in mapping stratigraphy, identifying faults, and determining the depth to bedrock.
Seismic reflection
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This involves measuring the travel time and direction of seismic waves that refract at subsurface interfaces due to differences in wave velocity.
Seismic refraction
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These are the most commonly conducted geophysical surveys for engineering investigations.
Seismic Methods
43
Seismic methods can be classified based on
different criteria, such as __________, __________, and __________.
wave type, survey technique, and application
44
Any mechanical vibration is initiated by a source and travels to the location where the vibration is noted.
Seismic Waves
45
The direction of travel of seismic waves is called the ________, __________, or__________.
ray, ray vector, or ray path
46
Two Major Classes of Seismic Waves
Body Waves
Surface Waves
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These are waves which pass through the volume of a material. These are the fastest traveling of all seismic waves.
Body Waves
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These travel through all media that support seismic waves; air waves or noise in gasses, including the atmosphere.
P-waves
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secondary or transverse or shear wave
S-waves
50
These waves do not exist in liquids and
gasses.
S-waves
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These waves are produced by surface impacts, explosions, and waveform changes at boundaries. These waves travel slower than body waves.
Surface Waves
52
A type of seismic surface wave in which particles move with a side-to-side motion
perpendicular to the main propagation
of the earthquake.
Love Waves
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An undulating wave that travels over the surface of a solid, especially of the ground in an earthquake, with a speed independent of wavelength, the motion of the particles being in ellipses.
Rayleigh Wave
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Seismic methods can be classified based on how seismic waves are generated and measured:
Active Seismic Methods
Passive Seismic Methods
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Active Seismic Methods
Seismic Refraction
Seismic Reflection
Seismic Tomography
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Passive Seismic Methods
Earthquake seismology
Microtremor analysis
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This is the study of seismic waves
generated by natural earthquakes.
Earthquake Seismology
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This is a passive seismic technique that
studies low-amplitude ground vibrations.
Microtremor Analysis
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Seismic methods are used in various fields, leading to classification by purpose:
Exploration seismology
Earthquake seismology
Engineering seismology
Environmental and groundwater studies
60
The seismic method relies on four key components to effectively analyze subsurface structures, these are:
Seismic Source
Geophones or Hydrophones
Seismograph
Data Processing
61
Generating seismic waves that propagate through the Earth. These sources can be natural, such as earthquakes, or artificial, like explosives, mechanical impacts, or specialized vibrators used in exploration.
Seismic Sources
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Serve as sensors. These are used on
land to record ground vibrations.
Geophones
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These are employed in water to capture pressure variations caused by seismic waves.
Hydrophones
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This equipment records input geophone voltages in a timed sequence. Current practice uses this to store the channels' signals as digital data at discrete time.
seismograph
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It involves filtering noise, enhancing signals, and applying mathematical algorithms to generate detailed subsurface images.
Data Processing
66
These detect the surface effects produced by electric current flow in the ground.
Electrical geophysical prospecting methods
67
Classification of Electrical Methods
Self-potential (SP) Technique
Telluric Current
Resistivity
Equipotential Method
Electromagnetic (EM) Methods
Induced Polarization (IP)
68
This technique is a passive electrical geophysical method based upon the measurement of spontaneous or natural electrical potential developed in the earth due to:
1) electrochemical interactions between minerals and subsurface fluids;
2) electrokinetic processes resulting from the flow of ionic fluids; or
3) thermoelectric mechanisms from temperature gradients in the subsurface
self-potential (SP) technique
69
This is also called Earth Current, natural
electric current flowing on and beneath the surface of the Earth and generally following a direction parallel to the Earth’s surface
Telluric Current
70
This is a measure of the resistance of a given size of a specific material to electrical conduction.
Resistivity
71
Resistivity may also be referred to as the _____________, or ______________.
specific electrical resistance, or volume resistivity
72
This was one of the first electrical
methods and was used as far back as 1912 by Schlumberger. As explained elsewhere in this volume, when electric energy is applied to two points at the ground surface, an electric current will flow between them because of their difference in electrical potential.
Equipotential Method
73
These use transmitters to create strong time-varying primary magnetic fields that
induce electrical currents to flow in conductive rocks. These currents, in turn, create secondary electromagnetic fields that are detected by receiver antennae.
Electromagnetic (EM) Methods
74
This and resistivity are two electrical properties measured in near-surface sediments as indirect hydrocarbon indicators. They are usually measured at the same time by inserting two electrodes into the earth surface and passing a current through them.
Induced Polarization (IP)
75
A method of geotechnical investigation that physically samples and tests soil, rocks, and groundwater to analyze underground conditions.
Direct Penetration
76
The purpose of direct penetration is to determine soil strength, density, and
composition __________, __________, and _________.
soil strength, density, and composition
77
This helps in designing stable foundations for buildings and infrastructure. This is also essential for assessing soil suitability for construction.
Direct Penetration
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Inclusion in Direct Penetration
Trenching
Pitting
79
This is a pit that is elongated over some distance in order to establish how the
surface conditions change over various parts of the work.
Trenching
80
This test pits are dug either manually or
with an excavator in order to reveal the
subsurface conditions to the depth desired.
Pitting
81
Types of Direct Penetration Tests
Standard Penetration Test (SPT)
Cone Penetration Test (CPT)
82
Measures soil resistance using a hammer-driven sampler.
Standard Penetration Test (SPT)
83
Determines relative density and shearing
resistance of cohesionless soils and strength of stiff cohesive soils.
Standard Penetration Test (SPT)
84
These are used for sands, silts, clays, and weathered rocks. These are common in foundation analysis for buildings, bridges, and roads. This provides an approximate guide to soil properties but is cost-effective and widely used.
Standard Penetration Test (SPT)
85
This is a common in situ testing
method used to determine the geotechnical engineering
properties of soils and assessing subsurface stratigraphy.
The test is also called, Dutch Cone test.
Cone Penetration Test (CPT)
86
Cone Penetration Test (CPT) is also called ___________.
Dutch Cone Test
87
Determines soil type, strength, and layering
without disturbing the ground significantly.
Cone Penetration Test (CPT)
88
This direct penetration test has the following advantages:
- No borehole required—fast and cost-efficient.
- Provides continuous soil profile readings.
- Best for soft clays, silts, and sands where sampling is difficult.
Cone Penetration Test (CTP)
89
A drilling method that extracts cylindrical cores of rock or soil for analysis.
Core Boring
90
Its purpose is to evaluate subsurface geology, identify rock formations and ground conditions, and it is essential for foundation design, tunneling, and
mining exploration.
Core Boring
91
A hollow cylindrical drill made of metal with
diamond or carbide tips for cutting through
surfaces.
Core Drill
92
cutting process that uses a drill bit to cut/enlarge a hole of circular cross-section in solid material
Drilling
93
Scaling, leaching, or pattern cracking can be signs of the need for ____________.
core drilling
94
Four Methods of Drilling
1. Percussion Drilling
2. Churn Drilling
3. Diamond Core Drilling
4. Rotary Drilling
95
It consists basically of a hammer unit
which is driven by compressed air. This hammer unit imparts a series of short, rapid, blows to the drill steel or rods and at the same time slowly rotates them. Mainly used for water well drilling and not commonly used in mineral expo.
Percussion Drilling
96
It is a drilling technique in which a sharpened steel bit attached to rope or cable is repeatedly raised and lowered
at the rate of 30-60 strokes/min and crushing the rock and making the hole deeper. Useful in exploration work for sampling soft formations up to a depth of
100-150 m.
Churn Drilling
97
Designed specifically for mineral exploration and is the most important type of drilling. Recovery of the core drill enables details of the geology, ground conditions and mineralogy to be obtain ed that is not possible with any other method.
Diamond Core Drilling
98
Two Types of Diamond Core Drilling
Conventional drilling
Wire line drilling
99
Type of diamond core drilling wherein the rods have to be removed from the hole each time. It is necessary to recover core from the core barrel.
Conventional Barrel
100
Type of diamond core drilling wherein the core can be removed from the hole without withdrawing the rods.
Wire Line Drilling
101
It is a placer sampling method where a
casing and chisel-pointed bit are advanced by percussion while water is forced ahead to loosen the material and to flush out and bring the sample to the surface. It is replacing churn drilling in many placer mining districts where minerals other than gold are involved.
Jet Drilling
102
They are important in soil sampling, beach
placer sampling, and in evaluating clay deposits. In any event, this stops at the first boulder.
Auger Drills
103
It is mostly used to drill big holes in large
quarries, open pit mines, petroleum extraction, and other fields.
Rotary Drills
104
Excavation or fills for any building structure and excavations or fills accessory thereto shall be so constructed or protected that they do not endanger life and property.
Whenever or wherever the depth of any excavation for a new construction is such that the lateral and subjacent support of the adjoining property or existing structure there on would be affected in a manner that the stability of safety of the same is in endanger, the person undertaking or causing the excavation to be undertaking or causing the excavation to be undertaken shall be responsible for the expense of underpinning or extending the foundation or footings of the aforementioned property or structure only when such underpinning is necessary for the safety of the same during excavation.
PD. 1096 National Building Code of the Philippines Section 08.01 Article 2 Paragraph B
105
Two Types of Percussion Drill
Down-the-Hole Hammer Drill
Top Hammer Drill
106
As the name implies, the hammer unit is lowered down the hole at the end of the rods.
Down-the-Hole Hammer Drill
107
In this type of drill, both percussive action and rod rotation are provided by a hammer unit which is track mounted on the rig and is moved up and down by a chain feed.
Top Hammer Drill
108
Diamond core drilling is invented by ______________, a French engineer.
Rodolphe Leschot
109
A mechanical device on a drilling rig that provides clockwise rotational force to the drill string to facilitate the process of drilling a borehole. It can obtain sample fragments by chopping its way through almost any kind of ground-unconsolidated, heterogeneous, hard, or completely fractured.
Rotary Drilling
110
Other Drilling Methods
Jet Drilling
Auger Drills
111
This is a cylindrical section of rock, or fragment thereof, taken as a sample of the interval penetrated by a core barrel and brought to the surface for examination and for analysis.
Core
112
All drill hole data gathering is called _________.
logging
113
This provides data and parameters necessary for mass classification and should be conducted so that the data can be easily applied to all industry standard classification systems.
Geotechnical core logging
114
This is a barrier that stops or restricts the flow of water or underground streams. Reservoir created by these not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aquaculture, and navigability.
dam
115
Geological Conditions for Construction of Dams
- Narrow River Valleys
- Occurrence of the bedrock at the shallow depth
- Competent rocks to offer a stable foundation
- Proper geological structures
- Spillway size and location
- Earthquake zone
116
Spillway disposes the surplus river discharge. The capacity of the spillway will depend on the ______________ to be by-passed. The spillway is therefore much more important on rivers and streams with large flood potential.
magnitude of the floods
117
If dam is situated in an earthquake zone, its design must include ______________.
earthquake forces
118
The type of structure best suited to resist earthquake shock without danger are ______________ and ________________.
earthen dams and concrete gravity dams
119
This is an underground passageway, dug through the surrounding soil/earth/rock and enclosed except for entrance and exit, commonly at each end.
tunnel
120
Geological Conditions for Construction of Tunnels
- The type of the rock and their strength and deformation behavior
- Geological discontinuities and associated strength and deformation behavior
- Groundwater conditions
- Squeezing and swelling rock conditions
- Running Ground
- Gases in rocks
- Rock temperature
- Topographic conditions
121
Type of the Rock and their Strength and Deformation Behavior
Igneous Rocks
Sedimentary Rocks
Metamorphic Rocks
122
Geological Discontinuities and Associated Strength and Deformation Behavior
Folds
Faults
Joints
123
These are sometimes the natural traps of natural gases, which might be harmful to the persons working in tunnels.
Folds
124
The orientation of these in relation to tunnel line is vitally important since this govern the length of tunnel affected by them and its accompanying zones.
Faults
125
These are structural plane of weakness and greatly affect shear strength of properties of rocks and rocks masses.
Joints
126
The presence of __________ is recognized as a major hazard in addition to causing operation difficulties in respect of tunnel construction works.
groundwater
127
a type of displacement into an excavation due to stress gradient created around the tunnel by excavation
Squeezing
128
is a time dependent process and involves physico-chemical reactions with water.
Swelling
129
This is often saturated and the presence of water can courage liquefaction when disturbed by tunnelling activities. This can arise at a later stage due to the progressive collapse and formation of a significant cavity tapping a major aquifer and overlying unconsolidated saturated deposits.
Running Ground
130
These are frequently in the sedimentary rock.
Gases
131
These have significant amounts of organic material generally in the excess of the total organic carbon.
Organic-rich sedimentary rocks
132
Temperature increases about _____ for every 60-80 meters in geologically stable areas and for 10-15 meters in volcanically active areas. Effective ventilations is perhaps the only mean to alleviate the problem.
10°C
133
The arrangement of the natural and artificial physical features of an area.
Topographic Conditions
134
A _______, or edifice, is a structure with a roof and wall standing more or less permanently in one place, such as a house or factory. They come in a variety of sizes, shapes, and functions, and have been adapted throughout history for a wide number of factors, from building materials available, to weather conditions, land prices, ground conditions, specific uses, and aesthetic reasons.
building
135
Geological Conditions for Construction of Buildings
- General Landforms
- Flood Risk
- Historical or present risk of landslide and subsidence
- Soil Types
- Drainage and Runoff
- Framed Structure
- Foundations
136
These are the building blocks of landscapes, so measuring the morphometric properties of these can help evaluate how and why the physical attributes of landscapes vary over time and space.
Landforms
137
If construction of a new building goes ahead on a site prone to flooding, minimize the risk by:
- ensuring the building is located on the highest section of the site
- building away from natural drainage paths or channels
- making the finished floor level of the lowest floor well above (600mm minimum) the maximum flood level.
- installing additional land drainage for low-lying areas.
138
Erosion of soil from deforestation, heavy rainfall, and poor land-use control, in addition to steep slopes add to the risk of ________ and __________.
landslides
building collapse.
139
This is the artificial removal of water, both surface and sub-surface. This is often a major element of civil engineering and construction projects and is necessary to avoid flooding and other damage.
Drainage
140
This is a building construction method where columns and beams support the load, allowing flexible design, open spaces, and lightweight walls
framed structure
141
The ________ conditions of rocks and soils are an important consideration for determining how surface construction loads are transmitted into the ground safely and for the lifespan of the project.
foundation
142
The main considerations of foundations are:
- strength or bearing capacity
- settlement (compressibility) and differential settlement
- volume change of the ground due to climatic conditions
- subsidence due to natural voids beneath the foundation, leading to ground failure.
