Review Question and Answers

Chapter 1

Q. 1 What is engineering geology ?

Ans. :

Engineering Geology is the application of the geologic sciences to engineering practice for the

purpose of assuring that the geologic factors affecting the location, design, construction, operation and

maintenance of engineering works are recognized and adequately provided for.

Q. 2 State the use of Engineering geology.

Ans. :

Engineering geologic studies may be performed during the planning, environmental impact

analysis, civil engineering design, value engineering and construction phases of public and private works

projects and during post-construction phases of projects. Works completed by engineering geologists

include geologic hazards, geotechnical, material properties, landslide and slope stability, erosion,

flooding, dewatering, and seismic investigations, etc.

Q. 3 State the importance of geology in civil engineering.

Ans. :

The role of geology in civil engineering may be briefly outlined as follows :

Geology provides a systematic knowledge of construction materials, their structure and properties.

The foundation problems of dams, bridges and buildings are directly related with geology of the area

where they are to be built.

The knowledge of ground water is necessary in connection with excavation works, water supply,

irrigation and many other purposes.

Q. 4 State the branches of geology.

Ans. :

1. Physical geology 8. Historical geology

2. Geomorphology 9. Applied geology

3. Mineralogy 10. Hydrology

4. Petrology 11. Indian geology

5. Structural geology 12. Photo-Geology

6. Stratigraphy 13. Relationship of Geology with Other Branches of Science.

7. Palaeontology

Chapter 2

Q. 1 State the difference between disintegration and decomposition.

Ans. :

Disintegration is the process by which the rock is broken into many small pieces by the distractive

mechanical action of the physical agent without chemical change whereas decomposition is the process

by which the rock is broken into many small pieces by chemical action.

Q. 2 Define Weathering.

Ans. :

The process by which the rock is decayed, disintegrated and decomposited with the action of the

distractive mechanical or chemical action of the physical agent of atmosphere like wind, water and ice is

called a weathering.

Q. 3 Differentiate between erosion and weathering.

Ans. :

Erosion is the process by which the rocks is broken into many small pieces by the distractive action

of the physical agent like wind, water and ice, characterized by motion whereas weathering is the process

by which the rock is decayed, disintegrated and decomposited with the action of the distractive

mechanical or chemical action of the physical agent of atmosphere like wind, water and ice.

Q. 4 What is scree and talus.

Ans. :

Scree : It is the frost formed angular, sub angular and irregular particles accumulated in conical heap.

Talus : It is the accumulated scree deposits lie along the full length of slopes.

Q. 5 State the factors affecting weathering.

Ans. :

1. Rock type and structure.

2. Slope

3. Climate

4. Animals

5. Time

Q. 6 Differentiate between Abrasion and Attrition.

Ans. :

Abrasion is the process by which a stream’s irregular bed is smoothed by the constant friction and

scouring impact of rock fragments, gravel, and sediment carried in the water whereas attrition is a

mechanical weathering process just like the abrasion in which transported sediments themselves due to

mutual collision.

Q. 7 State the structures formed by stream deposition.

Ans. :

1. Bars

2. Flood plains

3. Alluvial fans

4. Deltas

5. Meanders

6. Oxbow lake

Q. 8 Differentiate between meanders and oxbow lake.

Ans. :

Meander is the course of a stream bed can be continuously affected by erosion on the outside of

curve and deposition on the inside , transform a gentle curve into a hairpin whereas an oxbow lake is

formed when a meander begins to close on itself and the stream breaks through and bypasses the

meander.

Q. 9 What do you mean by river rejuvenation?

Ans. :

A river is said to be rejuvenated when the base level that it is flowing down to is lowered.

Q. 10 What are the cause of river rejuvenation ?

Ans. : Rejuvenation may result from causes which are the epeirogenic uplift of a land mass or worldwide decrease

in sea level.

Q. 11 State the types of drainage pattern developed in the stream.

Ans. :

1. Dendritic

2. Radial

3. Rectangular

4. Trellis

Q. 12 Explain engineering consideration of running water or stream or river.

Ans. : A running water is the most powerful agent of erosion. Thus, a detailed study of the soil

and velocity of running water is essential to provide the adequate safeguard in the design for the smooth

and successful work of project.

Rivers present have many practical problems to civil engineering projects, few of which are listed

below :

1. Dams, bridges are generally constructed across the river. The foundations of these structure are to

be rest on some firm strata and suitable measures are to be adopted.

2. Water power of the running water can be utilised to generate the hydro electricity.

3. Regulation of river channels are to be done for the navigation and flood control purposes.

4. River deposits such as sand, pebbles are the important construction material.

Q. 13 Define Water table.

Ans. : The upper surface of the groundwater is called water table.

Q. 14 Define oasis.

Meander

Ans. : Oasis a fertile tract of land that occurs in a desert wherever a perennial supply of fresh

water is available. It varies in size, ranging from 1 hectare around small springs to vast areas of naturally

watered or irrigated land.

Q. 15 What are the structures formed by wind erosion.

Ans. :

1. Ventifacts

2. Pedestal Rock / Mushroom Rocks

Q. 16 Explain pedestal rock.

Ans. :Pedestal rocks are the undercut vertical column of rocks which have wider tops, and narrow bases.

When wind blows, the sand particles being travel heavily near the surface and cause undercutting

or rock faces.

Fig. Q.16 : Pedestal rock

Q. 17 What are the structures formed by wind transportation.

Ans. :

(i) transverse dunes (ii) barchans

(iii) longitudinal dunes and (iv) complex dunes.

Q. 18 Explain Barchans

Ans. : Barchans are crescent shaped dunes the convex side of which faces the wind direction. Barchans are

formed where wind is nearly unidirectional. They occur in groups in areas of greatest sand supply.

Fig. Q18 : Barchans

The Q. 19 Explain Loess.

Ans. : The suspended load transported by wind consists mainly of silt and dust particles. When it settles, it forms a blanket deposits of silt, known as “loess”. These deposits are typically non-stratified and have a grayish yellow colour. Loess is composed of many minerals including quartz, feldspar, hornblende and calcite.

Q. 20 What are the structures formed by glacial erosion.

Ans. :

Striations

U-shaped Valleys

Hanging Valleys

Cirques

Serrate Ridges

Roche Moutonnees

Glacial Trough

Fiords

Q. 21 Explain Cirques

Ans. : The bowl-shaped hollows present at the glacier valley heads in the mountains, are called “cirques”. They are formed mainly be the quarrying and frost-wedging action of ice. In cirques, a little gap in generally left between the head of the glaciated alley and the mass of the glacier ice. This gap is known as the “bergschrund”.

Q. 22 Explain Roche Moutonnees

Ans. : These are small mounds of resistance bedrock which have a typically say metrical appearance. The side

facing the direction of ice advance is gentle and smooth, while the leeward side is steep and rough. This form results

from the plucking action on the leeward side and abrasion on the opposite side.

Q. 23 Explain Glacial Trough

Ans. : A ‘U’ shaped valley with steep sides formed by glacial erosion is called as glacial trough. The

glacial trough tends to have a straighter course than river valleys. The shape of a glacial trough more

resembles a parabola than the better ‘U’.

Q. 24 Differentiate between U-shaped Valleys and Hanging Valleys.

Ans. :

U shaped valleys is valley in which walls with flat floor are produced whereas in hanging Valleys,

at the junction where a tributary joints the main glacier, the floors of their valleys do not meet at the dam

level.

Q. 25 What are the structures formed by landform deposition.

Ans. :

Moraines

Outwash plains

Kettle Holes

Drumlins

Eskers

Kames

Varves

Buried Valley

Q. 25 Explain the term Ice Age.

Ans. : The Pleistocene epoch is called an “Ice Age”. The Ice age began at least 2.5 million years

ago and had a duration perhaps of a million years. The most recent retreat of ice had taken place between

10,000 and 15,000 years ago. The areas which were extensively buried by ice sheets included Northern

North America, northern Europe, and northwest Asia. In these areas ice sheets do not exist today.

Chapter 3

Q. 1 Define mineral.

Q. 2 Name the physical properties of the mineral.

Ans. :

Crystal Habit

Cleavage

Parting

Fracture

Hardness

Tenacity

Specific Gravity

Colour

Lustre

Streak

Electricity

Q. 3 Explain Cleavage

Ans. : Crystals often contain planes of atoms along which the bonding between the atoms is weaker than along other planes. In such a case, if the mineral is struck with a hard object, it will tend to break along these planes. This property of breaking along specific planes is termed cleavage.

Cleavage can be described by general forms names, for example if the mineral breaks into rectangular shaped pieces it is said to have cubic cleavage, for example : Galena, if it breaks into prismatic shapes, it is said to have prismatic cleavage, for example, Elaeolite or if it breaks along basal pinacoids, it is said to have pinacoidal cleavage, for example : Peninite.

Q. 4 Write a short notes on Hardness

Ans. : Hardness is determined by scratching the mineral with a mineral or substance of known hardness.

Hardness is a relative scale, thus to determine a mineral’s hardness, you must determine that a substance with a hardness greater than the mineral does indeed scratch the unknown mineral, and that the unknown mineral scratches a known mineral of lesser hardness.

Hardness is determined on the basis of Moh’s relative scale of hardness exhibited by some common minerals.

Q. 5 Explain Lustre

Ans. : Luster refers to the general appearance of a mineral surface to reflected light.

There are two general types of luster defined as follows :

1. Metallic 2. Non-metallic

1. Metallic :

Mineral looks shiny like a metal. Usually opaque and gives black or dark colored streak, for

examples : pyrite, galena.

2. Non-metallic :

Non metallic lusters are referred to as :

(a) Vitreous : Looks glassy, for examples, clear quartz, tourmaline.

(b) Resinous : Looks resinous, for examples, sphalerite, sulfur.

(c) Pearly : Iridescent pearl-like, for example, apophyllite.

(d) Greasy : Appears to be covered with a thin layer of oil for example, nepheline, talc.

(e) Silky : Looks fibrous, for examples, some gypsum, serpentine, malachite.

(f) Adamantine : Brilliant luster, for examples, diamond.

(g) Dull : No light is reflected, for examples, chalk, clay, bauxite, kaoline.

Q. 6 Differentiate between Lustre and streak

Ans. :

Lustre Streak

Luster refers to the general appearance

of a mineral surface to reflected light.

The color of a mineral when it is powdered is

called the streak of the mineral.

It is description of the way light interacts

with the surface of a mineral.

It is obtained by rubbing the mineral across

the surface of a hard, unglazed porcelain

material called a streak plate

Q. 7 How to use lustre as an identification mark of minerals.

Ans. :

It is in the eyes of the viewer to determine what luster a particular specimen exhibits. Luster is only

a useful form of mineral identification when the specimen in question displays a unique luster, such as

waxy, greasy, pearly, etc. Specimens with a vitreous luster cannot be distinguished from one another, nor

can minerals with a metallic luster. Luster is usually just noted as a mineral property, and is not

commonly usually used to help identify a mineral.

Q. 8 How will you determine the hardness of the mineral.

Ans. ; Hardness is determined on the basis of Moh’s relative scale of hardness exhibited by some common minerals.

Q. 9 What do you mean by Moh’s scale of hardness.

Ans. :

A scale to measure hardness was devised by Austrian mineralogist Frederick (Friedrich) Moh’s in

1822, and is the standard scale for measuring hardness. The scale consists of numbers one through ten; 1

being the softest and 10 being the hardest. Each number represents a different mineral - each harder than

the previous.

Q. 10 Differentiate between silicate minerals and non silicate minerals.

Ans. :

Silicate minerals Non silicate minerals

The minerals which all have the elements

silica and oxygen as their main

ingredients are the silicate minerals.

Some minerals do not contain a

combination of Silicon and Oxygen, as

silicate minerals do. These minerals are

called as non silicate minerals.

These are formed when molten rock

cools, either at or near the Earth’s surface

or deep underground.

Some of these groups form when magma

cools, while others form when water

evaporates away leaving mineral crystals

behind, or when other minerals

decompose.

Ex : Quartz, olivine, micas and feldspars are all examples of silicate minerals.

.

Ex : Nonsilicate minerals include very

valuable resources to humAns., such as the

precious metals gold, silver, and platinum,

useful metals like iron, aluminium and

lead, and the precious gems diamond and

ruby.

Q. 11 Differentiate between Mafic minerals and Felsic minerals.

Ans. :

Mafic minerals Felsic minerals

A mineral that is composed predominantly

of the ferromagnesian rock-forming

silicates.

Felsic minerals are usually higher in silica

(SO2) and aluminum and of lower density

than mafic minerals.

Ex : Olivine, pyroxene, amphibole, biotite

mica, and the plagioclase feldspars are the

mafic minerals.

Ex : Pyroxene, amphibole, olivine, mica,

and biotite are the Felsic minerals.

Q. 12 State the origin, structure, lustre , streak and cleavage of the following minerals. Orthoclase, Asbestos, Biotite, Bauxite, Diamond, Gypsum.

Ans. :

Minerals/ Properties

Orthoclase Asbestos Biotite Bauxite Diamond Gypsum

origin Igneous rock like granite

Metamorphic rock

Igneous rock, metamorphic rock

Igneous rock like granite

Igneous rock

Sedimentary rock

structures Monoclinic Monoclinic Monoclinic Amorphous Cubic Monoclinic

lustre Vitreous Sub-Vitreous, Vitreous Dull Resinous Vitreous,

silky Silky

streak White White Colourless White Colourless White

cleavage Perfect Perfect Perfect Uneven Perfect Perfect

Chapter 4

Q. 1 Define Petrology and rock.

Ans. :

Petrology :

Petrology, is the branch of geology, which deals with study of various types of rocks, their mode of

occurrence, their composition, textures, structures, geological and geographical distribution.

Rock : It is aggregates of the minerals.

Q. 2 What are the importance of petrology in civil engineering.

Ans. : Refer section “ Introduction” , Chapter 4

Q. 3 What are the types of rocks ?

Ans. : Igneous rocks, Sedimentary rocks, and Metamorphic rocks.

Q. 4 Define Rock cycle.

Ans. :

Rock is permanent over geologic time; instead, all rocks change slowly from one of the three rock

types to another. This continuous process is called the rock cycle

Q. 5 Define magma.

Ans. :

Under certain conditions, rocks of the upper mantle and lower crust melt, forming a hot liquid

called magma.

Q. 6 Define lava.

Ans. :

Under certain conditions, rocks of the upper mantle and lower crust melt, forming a hot liquid and

erupting through volcano is called lava.

Q. 7 Define Bowen’s Reaction Series.

Ans. :

A schematic description of the order in which minerals form during the cooling and solidification

of magma and of the way the newly formed minerals react with the remaining magma to form yet another

series of minerals. The series is named after American geologist Norman L. Bowen (1887-1956), who

first described the scheme.

Q. 8 Define igneous rock. State the name of few igneous rock.

Ans. :

An igneous rock forms when magma solidifies.

Name of Igneous Rocks : Basalt, Granite, Gabbros, Quartz, Rhyolite

Q. 9 Differentiate between Extrusive & intrusive rocks.

Ans. :

Extrusive rocks Intrusive rocks

An extrusive igneous rock forms when

magma erupts and solidifies on the Earth’s

surface.

An intrusive igneous rock forms when

magma crystallized within the crust.

The texture of these rocks are the fine

grained textureThe texture of rocks are the finer or coarse

grained depending upon the mode of

formation.

For examples : Deccan trap of India,

Basalts

For examples : Granites , Gabbros rocks,

Dolarites rocks.

Q. 10 State the name of igneous rocks based on silica content.

Ans. :

On the basis of the percentage of silica present in the rock, igneous rocks are classified as :

(i) acidic (ii) intermediate

(iii) basic and (iv) ultrabasic.

Q. 11 What are hypabyssal rock.

Ans. : The rocks formed at depth close to the crust are called as hypabyssal rocks.

Q. 12 Give the tabular form of Hatch’s classification system of igneous rocks.

Ans. :

Compositio

n

Silica Content Alkali Series Calc- Alkali Series

Acid > 66 % Granite, Rhyolite Granodiorite, Dacite

Intermediate 52-66 % Syenite, Trachyte Diorite, Andesite

Basic 45-52 % Alkali Gabbro, Alkali Basalt Gabbro, Basalt, Dolerite

Ultra Basic < 45% Dunite, Peridotite

Q. 13 Explain the composition of minerals of igneous rocks.

Ans. : Approximate mineral compositions of the more common types of igneous rocks for example :

granite rocks are summarized as under :

orthoclase 40% quartz 33%

plagioclase 13% mica 9%

hornblende 5%

Q. 14 Name the 5 types of textures of igneous rocks.

Ans. :

1. Phaneritic Texture

2. Aphanitic Texture

3. Porphyritic Texture

4. Poiklitic Texture

5. Vesicular Texture

Q. 15 Explain the vesicular texture of the igneous rocks.

Ans. : A texture in which vesicles (holes, pores, or cavities) within the igneous rock are clearly visible is called vesicular texture. Pumice and scoria are common types of vesicular rocks

Q. 16 What are the structures formed in igneous rocks.

Ans. :

1. Pillow Structures

2. Orbicular Structures

3. Sheet Structures

4. Vesicular Structures

5. Amygdaloidal Structures

6. Mural Jointing Structures

7. Columnar Jointing Structures

Q. 17 Define sill, dyke.

Ans. :

Sill : A sill is a sheet like tabular pluton that has intruded between older layers of sedimentary rock, beds

of volcanic lava or tuff, or even along the direction of foliation in metamorphic rock.

Dike : Dikes are the wall like columnar bodies that cuts discordantly across the bedding planes of the pre-

existing rocks.

Q. 18 Differentiate between Concordant bodies and Discordant bodies.

Ans. :

Concordant bodies Discordant bodies

The intrusive bodies in which magma is

injected always parallel to the bedding

planes , are called as concordant bodies.

The intrusive bodies in which magma is

injected across the bedding planes, are called

as concordant bodies.

Examples of the concordant bodies are

sill, phacoliths, lopoliths and laccoliths.

Examples of the discordant bodies are dikes,

batholiths and volcanic neck.

Q. 19 Define the volcanic neck.

Ans. :

A volcanic plug, also called a volcanic neck or lava neck, is a volcanic landform created when

magma hardens within a vent on an active volcano.

Q. 20 Define mural jointing structures.

Ans. : These structures are formed due to racks developed during cooling and solidification of

magma in the form of various cubical shaped block . It is seen in Granite rock.

Q. 21 Define column jointing structures.

Ans. : These structures are formed due to cracks developed during cooling and solidification of

magma in the form of various polygonal shaped block. It is seen in basalt and other volcanic rocks.

Columnar jointing in Trachyte, Western Express Highway, Malad, Maharashtra is the example in India.

Q. 22 Define vesicular structures.

Ans. : Magma typically has some gas in solution. During eruptions, that gas effervesces out of solution, like CO 2

bubbling out of a soda. As the magma freezes, these bubbles are preserved as vesicles, and rocks containing them

are called vesiclular. These are found in the Deccan Trap Basalt of India.

Q. 23 Define sheet structures.

Ans. :In this types, structures formed in the igneous rocks are composed of various sheet like layers. For example, these structures are generally found in Granitic Pluton . It is found at the tail channel of Gangapur Dam, Nashik, sheet jointing in basalt, at Parli Road, Satara in Maharashtra.

Q. 24 Define orbicular structures.

Ans. : In this types, structures formed in the igneous rocks are composed of ball like segregation. For example,

these structures are generally found in basalt rocks.

Q. 25 Define amygdaloidal structures.

Ans. : The vesicular structures in which the vesicles are filled with one or more of the secondary minerals such as

zeolites or different forms of silica or chlorophaeite. Such structures are called as amygdaloidal structures. These are

found in the Deccan Trap Basalt and railway cutting in Bor Ghat section of Central Railway India.

Chapter 5

Q. 1 What do you mean by clastic formation of sedimentary rocks.

Ans. :

Clastic sedimentary rocks, such as breccia or sandstone were formed from rocks that have been

broken down into fragments by weathering, which then have been transported and deposited elsewhere.

Q. 2 Define Diagenesis and marine environment.

Ans. :

Diagenesis : It is the process that turns sediment into rock.

Marine environment : A marine environment means the rock was formed in a sea or ocean.

Q. 3 What are the textures occurred in sedimentary rocks.

Ans. :

1. Sorting

2. Rounding

3. Maturity

Q. 4 Define Rudaceous rocks and arnaceous rocks.

Ans. :

Rudaceous rocks :

The rocks which include all the coarsed grained of more than 2mm size heterogeneous composition

are called as rudaceous rocks.

Arenaceous rocks :

The rocks which include all the sediment of size between 1/16 – 2 mm are called as arenaceous

rocks.

Q. 5 What are evaporites.

Ans. :

These sedimentary rocks are formed by the evaporation of saline lakes.

Example : Gypsum, Anhydrite, Rock salt, Borates.

Q. 6 Name the structures formed in sedimentary rocks.

Ans. :

1. Stratification

2. Rhythmic Layering

3. Cross Bedding

4. Graded Bedding 

5. Ripple Marks 

6. Mud Cracks

7. Raindrop Marks

8. Tracks and Trails

9. Secretions

10. Oolitic and Pisolitic Structures

Q. 7 Define mud rocks.

Ans. : Result from the drying out of wet sediment at the surface of the Earth.  The cracks form due to shrinkage of

the sediment as it dries. These cracks are also called as sun cracks. These indicate deposition at the land surface.

Q. 8 Define stratification in sedimentary rocks.

Ans. : Sedimentary rocks are laid down in layers called beds or strata. This phenomenon is

known as stratification or bedding. It is shown in Fig. Q.8.

Fig. Q.8 Bedding

Q. 9 Define Ripple Marks  in sedimentary rocks.

Ans. : The wavy undulations are formed on the surface of the bedding planes due to the

mechanical action of wind in loose and soft sediments. These are occurred under shallow water. (Fig.

Q.9)

Fig. Q.9 : Ripple marks

Q. 10 Define Tracks and Trails.

Ans. : These are the markings indicating the passage of some animals over soft sediment.

Chapter 6Q. 1 Define metamorphism and metamorphic rock.

Ans. :

Metamorphism : It refers to the changes in mineral assemblage and texture that result from

subjecting a rock to pressures and temperatures different from those under which the rock originally

formed.

Metamorphic rock : The rock formed by the process of metamorphism is a metamorphic rock.

Q. 2 Define grade of metamorphism.

Ans. :

Metamorphic grade is a general term for describing the relative temperature and pressure conditions

under which metamorphic rocks form.

Q. 3 What are the types of metamorphism.

Ans. :

1. Contact Metamorphism

2. Regional Metamorphism

3. Cataclastic Metamorphism

4. Hydrothermal Metamorphism

5. Burial Metamorphism

Q. 4 Define regional metamorphism.

Ans. :

When metamorphism occurs at high temperature and pressure levels it is said to be high grade

metamorphism, and it results in highly foliated and reorganized rocks with compositional layering

separating layers of different minerals. This type of metamorphism is called as regional metamorphism.

Q. 5 What are the rocks formed by the regional metamorphism.

Ans. :

Shale consists of clay minerals, quartz, and feldspar and is the most abundant sedimentary rock.

Q. 6 Define Contact metamorphism.

Ans. : Contact metamorphism occurs when country rock is exposed to high heat.

Q. 7 What are the rocks formed by the Contact metamorphism.

Ans. : Mica and chlorite.

Q. 8 Define dynamic metamorphism.

Ans. :

Dynamic metamorphism occurs in fault zones when country rock is ground up and partially

recrystallized.

Q. 9 What are the various textures produced in metamorphic rocks.

Ans. :

1. Foliated Texture

i) Slaty Texture

ii) Phyllitic Texture

iii) Schistose Texture

iv) Gneissic Texture

2. Non Foliated Texture

Q. 10 What do mean by Foliated Texture

Ans. :

The mineral constituents of foliated metamorphic rocks are oriented in a parallel or sub-parallel

arrangement. This texture is called as foliated texture.

Q. 11 Define Schistose Texture.

Ans. :

This is a foliated texture resulting from the sub-parallel to parallel orientation of platy minerals

such as chlorite or micas.

Q. 12 Define Gneissic Texture

Ans. :

This is a coarsely foliated texture in which the minerals have been segregated into discontinuous

hands, each of which is dominated by one or two minerals.

Q. 13 Differentiate between Foliated Rocks and non foliated Rocks.

Ans. :

Foliated Rocks Non foliated Rocks

If a rock is foliated, its name is determined

by the type of foliation present and the

dominant minerals.

If a rock is not foliated, its name is derived

from its chemical composition.

Ex. : kyanite schist , Slates are the foliated

rocks.

Ex : Quartzite, marble are the non

foliated rocks.

Q. 14 State the type of metamorphism for the following rocks : Schists, Gneiss, Quartzite,Slate

Ans. :

Schists : Regional metamorphic

Gneiss : Regional metamorphic

Quartzite : Dynamic or thermal or dynamothermal high grade metamorphism.

Slate : low grade dynamic or regional metamorphism

Q. 15 State the type of texture for the following rocks : Schists, Gneiss, Quartzite, Slate

Ans. :

Schists : Fine grained, schistose crystalline

Gneiss : Coarsed grained

Quartzite : Crystalline, interlocking, fine grained.

Slate : Fine grained

Q. 16 State the hydrology for the following rocks : Schists, Gneiss, Quartzite, Slate

Ans. :

Schists : Aquiclude

Gneiss : Generally, no prospects of ground water reservoir but Gneiss with good fractured

and foliated is a good acquifer.

Quartzite : Generally, no prospects of ground water reservoir, aquifuge.

Slate : Aquifer if water yield from factures

Chapter 7

Q. 1 Define structural geology.

Ans. :

Structural geology is the study of the features formed by geological processes. Features include

faults, folds and dipping strata.

Q. 2 What is fault.

Ans. :

When the strata on one side of a fissure have been shifted in any direction relatively to the beds on

the other side, so that the strata, which were once continuous across the fracture, are now separated by a

vertical interval and lie at different levels, the structure is called a fault.

Q. 3 What are the component of faults.

Ans. :

(i) Fault Plane (ii) Hanging Wall

(iii) Foot Wall (iv) Hade

(v) Throw (vi) Heave

(vii) Slip (viii) Strike

Q. 4 Differentiate between dip and strike.

Ans. :

The dip is the angle between a horizontal plane and the inclined plane, measured perpendicular to

the direction of strike whereas the horizontal distance perpendicular to the fault plane is called as strike.

Q. 5 Show the components of faults with sketch.

Ans. : Refer fig. Q.5

Fig. Q.5 : Component of Fault

Q. 6 State the relation between strike and dip.

Ans. : Dip is in the direction at right angles to the strike.

Q. 7 What is dip slip.

Ans. :

The movement of block parallel to the direction of the dip direction is called as dip slip.

Q. 8 What is strike slip.

Ans. :

The movement of block parallel to the direction of the strike direction is called as strike slip.

Q. 9 Differentiate between normal fault and reverse fault.

Ans. :

Normal fault Reverse fault

The Fault that result from horizontal

tensional stresses in brittle rocks and where

the hanging-wall block has moved down

relative to the footwall block, is called as

normal fault.

The Fault that result from horizontal

compressional stresses in brittle rocks and

where the hanging-wall block has moved up

relative to the footwall block, is called as

reverse fault.

It has a high angle of dip It has an angle of fault.

Q. 10 Differentiate between Strike Fault and Dip Faults.

Ans. :

Strike Fault are those which run parallel, or nearly so, to the strike of the beds whereas The fault in

which the fault plane is parallel to the dip of the beds is called as dip fault.

Q. 11 Enumerate the various faults.

Ans. :

1. Normal fault

2. Reverse fault.

3. Thrust fault.

4. Overthrust fault.

5. Horst and grabens

6. Strike fault

7. Dip fault.

8. Step fault.

Q. 12 How will you recognise the fault.

Ans. :(1) Slickenside are scratch marks that are left on the fault plane as one block moves relative to the

other. Slickenside can be used to determine the direction and sense of motion on a fault.(2) Discontinuity of strata shows the existence of a fault.

(3) Presence of the number of water springs in one line shows the existence of a fault along the spring line.

(4) Presence of exceptionally steeper slope than the surrounding ones shows the existence of a fault.

Q. 13 What is fold.

Ans. :

When rocks deform in a ductile manner, instead of fracturing to form faults, they may bend or fold

and the resulting undulating shaped structures are called folds.

Q. 14 What are the components of fold.

Ans. : The fold has the following elements :

(i) Limb (ii) Crest (iii) Trough (iv) Axial Plane

(v) Axis of fold (vi) Plunge of fold

Q. 15 Differentiate between axial plan and axis of fold.

Ans. :

An imaginary plane which divides the fold into two equal halves is called the axial plane whereas

The line of intersection between the axial plane and the surface of any of the constituent rock bed is called

the axis of fold.

Q. 16 Differentiate between crest and trough of fold.

Ans. :

The curved portion of the fold at the top are called the crest. whereas The curved portion of the fold

at the bottom are called the trough.

Q. 17 State the types of fold based on its appearance.

Ans. :

1. Anticline

2. Syncline.

Q. 18 State the types of fold based on position of axial plane.

Ans. :

1. Symmetrical fold

2. Asymmetrical fold

3. Overturned fold

4. Isoclinal fold

5. Recumbent fold

Q. 19 State the types of fold based on its size.

Ans. :

1. Anticlinorium

2. Synclinorium

Q. 20 Differentiate between dome and basin fold.

Ans. :

The fold in which the limbs are up-folded in an arch like structure and dip away in all directions

from a common centre is called as dome fold whereas The fold in which the limbs are down-folded in a

trough like structure and dip in from all directions to a common centre is called as basin fold.

Q. 21 State the causes of fault.

Ans. :

1. When a sequence of layered rocks is shortened parallel to its layering, this deformation may be

accommodated in a number of ways, homogeneous shortening, reverse faulting or folding.

2. Fault bend folds are caused by displacement along a non-planar fault.

Q. 22 What is joint. What are its types.

Ans. :

Joints : Joint are defined as a fracture in rock where there has been no lateral movement in the plane

of the fracture (up, down or sideways) of one side relative to the other.

Types of joints :

(i) Tight joint

(ii) Block or Mural joint

(iii) Sheet joint

(iv) Columnar joint

(v) Strike joint

(vi) Dip joint

(vii) Oblique joint

Q. 23 What is difference between joint and fault.

Ans. :

Joint is the fracture in rock without any displacement whereas fault is fracture in rock along which

displacement occurs.

Q. 24 Define conformity.

Ans. : Consider the stratified rocks as made up of beds which follow upon one another, in orderly sequence, and as

being affected alike by the elevation or depression, folding or dislocation, to which they may have been subjected.

Strata which have thus been laid down in uninterrupted succession, with sensibly parallel bedding-planes, and which

have been similarly affected by movements, are said to be conformable, and the structure is called conformity.

Q. 25 Define unconformity.

Ans. : In many places, however, the strata exposed in a section are very obviously divisible into two groups, each

made up of a series of conformable beds, but the upper group, as a whole, is not conformable with the lower, but

rests upon its upturned edges, or its eroded surface.

Q. 26 What is difference between Angular unconfirmity and Non Confirmity.

Ans. :

The unconfirmity in which the structure implies that the lower series of beds was first laid down

under water, and that these beds were then upturned, tilted, or folded to form a land surface, is called as

angular unconformity whereas The unconformity in which the older beds formation is made up of

plutonic igneous rocks lying below the younger bed of sedimentary rocks, is called as non confirmity.

Q. 27 What is difference between Outlier and Inlier.

Ans. :

Outlier is an outcrop of younger rocks surrounded by the outcrop of the old rocks whereas inlier

is an outcrop of old rocks surrounded by the outcrop of the younger rocks.

Chapter 8

Q. 1 State the geological condition of dam site.

Ans. :

(i) The site along the river valley which has the least area cross-section shall be selected.

(ii) The site should be free from severe leakage otherwise safety of the dam is affected.

(iii) The site should have very strong and stable rocks.

(iv) The site having igneous rocks is safer for dam as comparing with sedimentary rock particularly

shale’s, poorly cemented sandstones and cavernous limestone’s

(v) Occurrence of metamorphic rocks like geneses are also suitable as dam site and schist’s are

undesirable.

(vi) The site should be free from intrusions.

(viii) A dam site with fault zones should be treated careful if there is fault at site.

Q. 2 State the Geological Problem of Dam Sites.

Ans. :

The following geological problems that are usually met with at dam sites.

(i) Dams on shale (ii) Dams on soluble rocks

(iii) Dams on strata dipping upstream (iv) Dams on strata dipping down stream

(v) Dams built across strike of rocks (vi) Dams on jointed and permeable rocks

Q. 3 Explain the suitability of dam to be constructed on strata dipping upstream.

Ans. :The dams located on rocks dipping upstream represent ideal foundation conditions. These strata are

most capable of supporting the weight of dams and the pressure of the reservoir because the

resultant of these two forces acts nearly at right angles to the bedding planes of rocks (Fig. Q.3).

Also, the water in the reservoir does not percolate below the dam due to the upstream dip of rocks.

As a result the leakage of water and the development of uplift pressure will be minimum. (See Fig.

Q.3)

Fig. Q.3 : Dam on rocks dipping upstream

Q. 4 Explain the suitability of dam to be constructed on strata dipping down stream.

Ans. :The dams constructed on rocks dipping downstream (Fig. Q.4) may not be safe due to the

following reasons :

(a) The percolation of water may lubricate the junctions of rock bed, which may facilitate

sliding of dam.

(b) The water percolating through the strata dissolves the cementing materials of rocks and

enlarges the openings by mechanical erosion. This undermines the strength of the rocks and

increases the seepage of water.

(c) The water, which enters into the openings of rocks below the dam, causes the development

of uplift pressure, which tends to decrease the stability of the structure.

(d) In Fig. Q.4, R is the resultant of the weight of the dam and pressure of the reservoir water. In

this case, this resultant acts nearly parallel to the bedding planes and endangers the stability

of the dam.

Fig. Q.4 : Dam on strata on dams upstream dipping downstream

Q. 5 Explain the suitability of dam to be constructed across strike of rocks.

Ans. : The best foundation condition is when only one uniform rock is present along the length of a dam. If a dam is

aligned across the strike of strata, its foundation will be on different rock types of varying properties. In such a case

there are changes of unequal settlement of the dam. Further, as the bedding planes of the strata lie across the axis of

the dam, there is a possibility of serious leakage of water not only through the porous beds but through bedding

planes also (Fig.Q.5).

Fig. Q.5 : Dam aligned across the strike of rocks

Q. 6 Explain the suitability of dam to be constructed on jointed and permeable rocks.

Ans. :Where highly fissured, jointed and permeable rocks exist below the dam, they will not only leakage

of water, but also build uplift pressure at the base of the dam. The uplift pressure acts opposite to

the weight of the structure and it may cause sliding such rocks may be consolidated by grouting.

Q. 7 Explain the suitability of dam to be constructed on shale.

Ans. : (i) The cementation shales are stronger and do not disintegrate when subjected to wetting and drying.

(ii) The compaction shales on the other hand are soft and they slake when subjected to

alternate wetting and drying. Their bearing strength is low and they become plastic when

wetted. The compaction shales have a tendency to flow away from the loaded area and

therefore the structure settles. Swelling and caving may result during the excavation work,

which may cause trouble. If dams have to be built on compaction shales, heavier structures

like gravity dams should be avoided. After excavating the weathered rock either concrete

should be placed immediately without delay or its surface should be coated with asphalt to

avoid swelling and caving.

Q. 8 Explain the suitability of dam to be constructed on soluble rocks.

Ans. :The soluble rocks include limestone and dolomites and marbles. These rocks are generally

sufficiently strong to support the weight of the dam, they may contain underground solution

channels and caverns. If such solution channels are present at a dam site, the leakage through them

may be on such a large scale that the reservoir may not hold water for long. The treatment of such

openings is very expensive therefore; they should be carefully looked for in the soluble rocks

before constructing a dam.

Q. 9 What are the treatment given to Fracture Occurs at Dam Site.

Ans. :

1. Grouting the fractures.

2. Shortcrete.

Q. 10 How will you treat the dam site if leakage occurs.

Ans. :

Leakage occurs at dam site due to fracture found at site which are rectified using method of

grouting or by applying the shortcrete to fill the fractures.

Q. 11 What is problem of tunnel to be proposed in horizontal strata.

Ans. :Such a situation is rare in occurrence for long tunnels. When encountered for small tunnels or for

short lengths of long tunnels, horizontally layered rocks might be considered quite favourable. In

massive rocks, that is, when individual layers are very thick, and the tunnel diameter not very large,

the situation is especially favourable because the layers would overbridge flat excavations by acting

as natural beams (Fig. Q.11a). However, when the layers are thin or fractured, they cannot be

depended upon as beams; in such case, either the roof has to be modified to an arch type or has to

be protected by giving a lining (FigQ.11b).

Fig. Q.11a: Safe situation Fig. Q.11b: Unsafe at the top

Q. 12 What is problem of tunnel to be proposed when tunnel axis parallel to the dip direction

Ans. :When the tunnel axis is parallel to the dip direction (which means it is at right angles to the strike

direction), the layers offer uniformly distributed load on the excavation

(Fig. Q12). The arch action where the rocks at the roof act as natural arch transferring the load on

two sides comes into maximum condition. Even relatively weaker rocks might act as self-

supporting in such cases. It is a favourable condition from this aspect. However, it also implies that

the axis of tunnel has to pass through a number of rocks of the inclined sequence while going

through parallel to dip.

Q. 13 What is problem of tunnel to be proposed when tunnel axis driven parallel to the strike direction

Ans. :When the tunnel is driven parallel to strike of the beds, the pressure distributed to the exposed

layers is asymmetrical along the periphery of the tunnel opening : one half would be bedding

planes opening into the tunnel and hence offer potential planes and conditions for sliding into

opening. The bridge action, though present in part, is weakened due to discontinuities at the

bedding planes running along the arch

(Fig. Q13).

Fig. Q12 : Tunnelling parallel to the dip Fig. Q13 : Tunnelling parallel to layers (against the dip direction) to the strike

Q. 15 What do you mean by soft ground tunneling.

Ans. :

Tunnelling in unconsolidated rocks or loose sediments or shales and clays which require immediate

support after excavation is known as Soft Ground Tunnelling.

Q. 16 What do you mean by reservoirs.

Ans. :

Reservoir is an extensive large storage facility for a predetermined quantity of water behind a dam

constructed across a river.

Q. 17 State the site selection criteria for reservoir site.

Ans. :The following criteria shall be considered for the suitability of site for reservoirs.

(i) An effective storage.

(ii) Water tightness.

(iii) Do not split up soon.

(iv) A good reservoir site would be a valley section constricted by a narrow gorges at its outfall with

steep banks.

(v) A reservoir site should cover a small area but has a great depth to provide the adequate capacity so

as evaporation losses are minimum.

(vi) A site should have very low rate of silting.

(vii) A site should be free from anticlinal strike valley or faults valley.

(viii) A site should not have buried river channel which is source of leakage.

(ix) A site should not have the porous and permeable rocks ( i.e. aquifers).

Q. 18 Differentiate between erosion valley and structural valley.

Ans. :

Erosion valley are the most common type produced by headward erosion and subsequent deepening

and widening of stream valleys. Example : An anticlinal strike valley. Whereas Valley produced by down

folding or faulting of rock strata. These however are uncommon. Example : Synclinal Valleys, Fault

Valleys.

Q. 19 State the suitability of reservoir site at which granite rock is found.

Ans. :

Site having massive hard and resistant granites rocks provide excellent sites for reservoirs. These

rocks are traversed by open mural or sheet joints as can be seen in the exposed rocks in the valley floor

and banks.

Q. 20 State the suitability of reservoir site at which metamorphic rock is found.

Ans. :

Banded, bedded and foliated metamorphic rocks like Quartzites and Schists permit large scale

leakage through bedding planes joints and foliation planes. These site are not suitable but it can used with

proper treatment.

Q. 21 State the suitability of reservoir site at which sedimentary rock is found.

Ans. :

Valley sections cut in massive sedimentary formations may be impermeable but in case of stratified

formations like sandstones, the rocks are rendered blocky and more permeable by erosional enlargement

of bedding planes joints and development of notches, fissures etc. These site are not suitable but it can

used with proper treatment.

Chapter 9

Q. 1 What is volcanism.

Ans. :

The Volcanism is the process in which intrusion of lava inside the earths crust and also its extrusion

over the surface occurs.

Q. 2 Differentiate between creater caldera.

Ans. :

At and around the mouth of volcanic cone, a depression of basin shaped is found, called as creater.

Exeptonally, large sized diameter creater is called as caldera.

Q. 3 Explain Fumaroles.

Ans. :

In Fumaroles, during eruption only hot gases come out regularly or intermittently without solid

materials through fissures or cracks. For example : solfatars are discharging sulphurous vapours.

Q. 4 What is the engineering significance of volcano.

Ans. : With the development of knowledge of volcanic activities, now it becomes possible to predict the

time, its effect and place at which volcanoes will be occurred. Also, it is seen that the volcanoes damages

the man made structures, properties and loss of human life.

Thus, its knowledge is important for engineering projects. So, engineers has to select the suitable

site with the help of geolosits to safe the massive and important structures against damages without the

loss of human life. But, the site at which volcanoes of low intensity occurred, is suitable for poles for

electricity and telegraphic.

Q. 5 Define earthquake.

Ans. :

An earthquake is the result from the sudden release of stored energy due to sudden vibrations of

the Earth’s crust that creates seismic waves.

Q. 6 State the effects of earthquake.

Ans. :

1. Shaking and ground rupture

2. Landslides and Avalanches

3. Soil liquefaction

4. Tsunamis

5. Human impacts

Q. 7 State the causes of earthquake.

Ans. :

(i) Movements of tectonic plates

(ii) Volcanic eruptions

(iii) Anthropogenic sources

(iv) Dams

(v) Use of explosives

(vi) Sport games

(vii) Injection and Extraction of Fluids

(viii) Removal of natural gases

Q. 8 What is the difference between focus and epicentre.

Ans. :

The “focus” of an earthquake, also called its “hypocentre”, is the point below ground level where

the earthquake originates and generates shock waves which generates in all direction; e.g. where the snag

on the fault shears whereas the “epicenter” is the point at the ground level, immediately above the focus.

Q. 9 What are Isoseismal lines.

Ans. :

These are the line joining the places with equal seismic intensity i.e. lines joining points where

similar ground motions were experienced; they are assessed by examining the damage done.

Q.10 What is the difference between magnitude and intensity of earthquake.

Ans. :

Magnitude is a quantitative measure of the actual size of the earthquake whereas intensity is a

qualitative measure of the actual shaking at the location during an earthquake.

Q. 11 What is the use of Richter Scale.

Ans. :

The magnitude of earthquake is measured with the help of Richter Scale.

Q. 12 What do you by seismic waves. What are the various types.

Ans. :

Seismic waves : During each earthquake, the elastic waves are generated which are travel in each

directions are termed as seismic waves.

Types of seismic waves :

i)P waves

ii)S Waves

iii) L wvaes

iv) Rayleigh Waves

Q.13 : Classify the earthquake based on depth.

Ans. :

Type of Earthquake Depth of Shock

Shallow upto 60 km

Intermediate Between 60 km to 300 km

Deep Above 300 km

Q.14: What do you mean by seismic scale. What are its various types.

Ans. :

Seismic scale : A seismic scale is used to measure and compare the relative severity of earthquakes.

Types of Seismic scale :

1) Richter Scale

2) Mercalli intensity scale

3) Modified Mercalli Scale

Q.15 : State the name of equipments with which earthquake is measured.

Ans. : A seismograph

Q.16 : State 4 points to be considered for designing and construction of structures for earthquake affected areas.

Ans. :

1) The foundation should be provided over the hard rock with no sign of faults.

2) The building should be symmetrical and rectangular in plan.

3) Min. 16 mm diameter reinforcing bar should be used in all structural members of RCC buildings.

4) Double reinforced should be provided in case of RCC structures.

Q.17 : In how many zones India is divided.

Ans. : The seismic map has been revised again in the year 2002 and the new zone map has now have only four seismic zones : II, III, IV and V.

Q.18 : What is plate tectonics.

Ans. : The theory that the lithosphere is made up of moving plates i.e. sliding of Earth’s mass takes place

in pieces called Tectonic Plates.

Q.19 : What are the effects of plate tectonics.

Ans. : The movement of tectonic plates has the following effects on earth’s surface :

1) Mountains are formed due to the movement of plates towards each other and colloids

2) Volcanic eruption would occur due to movement of plates away from each other thereby generating

a gap which becomes the likely place for upward movement of magma.

3) Rift valleys are formed due to the sinking of medial block along two parallel faults and

4) Tectonic valley also develops when a trough like depression is created by synclinal folding of the

strata.

5) Tectonic earthquakes are produced due to the folding or faulting.

Q.20 : What do you mean by tectonic earthquake.

Ans. : The tectonic earthquakes are the most common which are occurred due to movement of tectonic

plates and directly and indirectly change the structural features of the earth’s crust.

Q.21 : What is landslides.

Ans. : The term “landslide” describes a wide variety of processes that result in the downward and

outward movement of slope-forming materials including rock, soil, artificial fill, or a combination of

these. The materials may move by falling, toppling, sliding, spreading, or flowing.

Q.22 : What are the causes of landslides.

Ans. : 1. Geological Causes :

Weak or sensitive materials

Weathered materials

Sheared, jointed, or fissured materials

Adversely oriented discontinuity (bedding, schistosity, fault, unconformity, contact, and so

forth)

Contrast in permeability and/or stiffness of materials.

2. Morphological Causes :

Tectonic or volcanic uplift

Glacial rebound

Fluvial, wave, or glacial erosion of slope toe or lateral margins

Subterranean erosion (solution, piping)

Deposition loading slope or its crest

Vegetation removal (by fire, drought)

Thawing

Freeze-and-thaw weathering

Shrink-and-swell weathering

3. Human Causes

Excavation of slope or its toe

Loading of slope or its crest

Drawdown (of reservoirs)

Deforestation

Irrigation

Mining

Artificial vibration

Q.23 : How to Reduce the Effects of Landslides

Ans. :

The hazard from landslides can be reduced by avoiding construction on steep slopes and existing

landslides, or by stabilizing the slopes. Stability increases when ground water is prevented from rising in

the landslide mass by

(1)  Covering the landslide with an impermeable membrane,

(2) Directing surface water away from the landslide,

(3) Draining ground water away from the landslide, and

(4)  Minimizing surface irrigation. Slope stability is also increased when a retaining structure and/or the

weight of a soil/rock beam are placed at the toe of the landslide or when mass is removed from the

top of the slope.

Chapter 10

Q.1 What do you mean by rock mechanics.

Ans. : Rock mechanics is a discipline that uses the principles of mechanics to describe the behaviour of

rocks.

Q.2:State the Physical Properties of Rock Material.

Ans. :

1.Density

2.Porosity

3.Permeability

4.Water content.

5.Hardness

6.Abrasivity

7.Wave velocity

Q.3 : What is compressive strength of rock. State the compressive strength of any 2 rocks.

Ans. :

Compressive strength is the capacity of a material to withstand axially directed compressive forces.

Rock Compressive strength

Granite 100-300 Mpa

Basalt 100-350Mpa

Q.4 : What is tensile strength and shear strength of rock.

Ans. :

Tensile strength : It is the capacity of a material to withstand axially directed tensile forces.

Shear strength : Shear strength is used to describe the strength of rock materials, to resist deformation due

to shear stress.

Q.5 : What is effect of confining pressure on strength of rock.

Ans. : With increasing confining pressure,

(a) The peak strength increases;

(b) There is a transition from typically brittle to fully ductile behaviour with the introduction of plastic

mechanism of deformation;

(c) The region incorporating the peak of the axial stress-axial strain curve flattens and widens;

Q.6 : What is effect of water content on strength of rock.

Ans. : Many tests showed that the when rock materials are saturated or in wet condition, the uniaxial

compressive strength is reduced, compared to the strength in dry condition.

Q.7 : How will you calculate Uniaxial compressive strength.

Ans. : Uniaxial compressive strength, σc, is calculated as the failure load divided by the initial cross

sectional area of the specimen.

Q.8 : List the various Tensile Tests.

Ans. :

1). Direct Tension Test

2) Brazilian Tensile Strength Test

Q.9 : List the various shear strength Tests.

Ans. : (1) Direct Punch Shear :

(2)Shear Strength Determination by Triaxial Compression Results

Q.10 : What is the effect of water content on unconfined compressive strength of intact rock.

Ans. : Researchers have studied the effect of water content on the strength of intact rocks. The unconfined compressive strength of intact rocks decreases as the water content increases.

Q.11 : How will you calculate the tensile strength of intact rock.

Ans. : Tensile strength from the unconfined compressive strength.

t = –

Where, t = Tensile strength of intact rock

c = unconfined compression strength of intact rocks.

Chapter 11

Q.1: What is the necessity of insitu test.

Ans. : For the satisfactory performance of engineering structures, the ground must be carefully studied by investigations conducted in-situ. Engineering structures such as roads, dams, buildings, tunnels and other underground works, are normally constructed according to the requirements of a specific design and from selected construction materials: by observing these requirements the strength of the completed structures is known and their response to load and displacement may be predicted. To obtain comparable information about the soil and rock against which the structure will react, it is necessary to understand the geological processes which formed the soils and rocks, this being the only way to reveal their 'design', and the nature of the materials of which they are composed.

Q.2 : What are the various insitu test.

Ans. :

1) Pressure Tunnel Test

2) In-Situ Shear Test

3) Tests in Boreholes

(i) Standard Penetration Test

(ii) Dynamic Cone Penetration Test

(iii) Static Cone Penetrometer

Chapter 12

Q.1 : What are the necessity of ground improvements.

Ans. : Ground ‘as is’ not adequate for the proposed project :

Too soft / weak to support a particular structure.

Too compressible.

Too much settlement (differential settlement) leading to damage and/or too muchlong-term settlement (on-going damage).

Too loose (sandy/silty soil).

If unsaturated, susceptible to densification under dynamic loading (settlement).

If saturated, susceptible to liquefaction under dynamic loading (complete loss of strength).

Q.2 : How the ground can be done.

Ans : Remove the inadequate soil, and replace with ‘better’ soil-occasionally the best option (e.g. shallow peat layers).

Transfer foundation loads down through the inadequate layer to stronger layer underneath, using piles or similar.

Improve the soil - if the soil is :

o Too loose (sand) - densify it (dynamic compaction, vibroflotation).

o Too permeable - inject something into the soil pores to reduce the permeability.

Q.3 : What is meaning of grouting.

Ans. : Pressure grouting involves the injection under pressure of a liquid or suspension into the voids of a soil or rock mass or into voids between these materials and an existing structure.

Q.4 : What is purpose of grouting.

Ans. : The primary purposes of pressure grouting a soil or rock mass are to improve the strength and

durability of the mass and/or to reduce the permeability of the mass.

Q.5 : Define rock reinforcement.

Ans. : Rock reinforcement including rock dowels and bolts are used to hold loose (key) blocks in place and/or to knit together the rock (ground) arch that actually provides the support for an opening in rock.

Q.6 : Define rock dowel.

Ans. :

Rock dowels are passive reinforcement elements that require some ground displacement to be

activated.

Q.7 : What are the rock bolts.

Ans. :

Rock bolts have a friction or grout anchor in the rock and are tensioned as soon as that anchorage is

attained to actively introduce a compressive force into the surrounding ground.

Chapter 13

Q. 1 Define RQD.

Ans. :

RQD is defined as the percentage of intact core pieces longer than 100 mm (4 inches) in the total

length of core.

Q. 2 Give the formula for calculating RQD.

Ans. :

RQD = 100%

where Li = length of i-th drill-core piece longer than twice the core diameter,

LT = total length of drill run,

N = number of core pieces longer than twice the core diameter.

Q. 3 What is the use of RQD.

Ans. :

RQD is intended to represent the rock mass quality in situ. RQD (rock quality designation) is an

indirect measure of fracture spacings observed in a drill-core run.

Q. 4 Explain the classification of rock based on RQD.

Ans. : From the RQD index, we can classify rock mass

RQD Rock mass quality

<25% Very poor

25-50% Poor

50-75% Fair

75-90% Good

90-100% Excellent

Chapter 14

Q. 1 Name the engineering properties of building stones.

Ans. :

Crushing strength

Transverse strength

Porosity

Absorption value

Density

Frost and Fire resistance

Q. 2 What are general properties of building stones.

Ans. : In order to select the suitable stone, the followings are the general properties of stones in addition

to the properties as discussed earlier.

(i) The stone must be free from cracks, cavities, holes, band.

(ii) The stone must be durable i.e. it should not be easily affected by weathering agents.

(iii) The stone must be tough and impervious.

(iv) For civil engineering projects, the specific gravity of the building stone should not be less than 2.6.

(v) The stone must be capable of preserving their colour uniformly for a long time.

(vi) The stone must not be so hard as to make dressing difficult and at the same time it must be hard

enough to have adequate strength. The fine grained, compact, homogeneous rocks are suitable for

dressing.

Q. 3 State the use of Granite as building stone.

Ans. :It is the most commonly used stone of igneous origin possessing a very high crushing strength. It has also low absorption value, least porosity and good interlocking structures. It can take an ornamental finish and fine polish.

The granites are suitable for concrete, building stones, railway ballast, road metal etc.

The granites are found in abundance in Gujrat, Mysore, Belgaum, Ajmer.

Q. 4 State the use of Basalt as building stone.

Ans. : It is the most commonly used stone of igneous origin possessing a very high crushing strength.

It has also low absorption value, least porosity and good interlocking structures. It can take

an ornamental finish and fine polish.

The basalts are suitable for concrete, railway ballast, road metal etc. and are not suitable as

building stones due to their dull and unpleasant colour.

The basalts are found in abundance in Deccan traps of western and central India.

Q. 5 State the use of lime stone as building stone.

Ans. : It is the most commonly used stone of sedimentary origin possessing a low crushing strength.

It has good absorption value and porosity.

The limestones are of various types but all types are not suitable as building stones. Only

compact and durable limestones are suitable as building stones. Limestones are also used for

making lime and cement.

Q. 3 State the use of marble as building stone.

Ans. : It is the most commonly used stone of metamorphic origin possessing a sufficient crushing

strength. It has low absorption value and least porosity, good interlocking structures. It can

take an ornamental finish and fine polish.

The marbles are suitable for ordinary structural work as well as for decorative purpose because

of their beautiful colours.

Q. 4 State the use of slate as building stone.

Ans. : It is the most commonly used stone of metamorphic origin possessing a perfect cleavage

because of which it can not be used as a building stone except for paving and roofing

purpose.

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