Site Report Geology NEW (Repaired)

CHAPTER 1 1.0 INTRODUCTION The trip to Ayer Hitam and Pulau Mawar, Johor is a programmer that oriented by the academic under Engineering Geology Subject, BFC 21303. The main purpose of this site visit is to expose the student about the real life situation at the geological site and our interest for this site visit is to learn more about the study of rock thus the problems occur related with rock and give the exposure to the students about the building material and raw material that oriented by the geology material. Besides that, it is also to reveal student into types rock study before this and the reason we choose the place because it will give exposure to the students or participants in determine cut slope stability and recovering method. 1.1 Objective i. ii. iii. iv. v. vi.

To carry out an appropriately comprehensive desk study in contex of the site visit / engineering project To recognize, identify and observed distinguishing features of rock in the field To plot poles and grest circle of the circle of the structural geology data. To identify the major and minor discontinuities set, plot the great circle of discontinuities and analyze the failure modes To identify which discontinuities are potential to fail and calculate the factor of safety To identify the rock slope stabilization technique applied in the fields.

1.2 Learning outcomes i. Student will appreciate the need of preliminary desk study process prior to field investigation ii. Student will be able to identify rocks and its structure geology iii. Student will be able to use the geological compass iv. Student will be able to measure the dip and dip direction of any geological or other uniform planes v. Student will be able to plot poles and great circles of the structural geology data vi. Student will be able to analyze the potential failure modes vii. Student will be able to calculate the safety factor for plane failure and wedge failure viii. Student will be able to recognize some types of rock slope stabilization CHAPTER 2

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2.0 LITERATURE REVIEW 2.1 Theory Geological mapping of surface outcrops or existing cuts, in similar geological formations ti that in which the excafation will be made, usually furnishes the fundamental information on site condition required for slope design. While mapping is a vital part of the investigation program it is also an inexact process because a certain amount of judgement is usually required to extrapolate the small amount of information available from surface outcrop to the overall cut slope. The processes involved in geological mapping are identifiying type of rock, measurement discontinuities orientation an identify the characteristic of discontinuities.

2.2 Introduction Of Geology Geology is the study of this planet Earth, its origin, history, composition, structure and dynamics of how it changes. It is an interdisciplinary field, in which principals of geosciences are used to solve engineering and environmental problems. It connects geology, civil engineering and other field to provide a versatile set of skills applicable to a wide range of contemporary problems. Engineering Geology in practice are responsible in civil engineering project that involve the earth or earth material include the identification and evaluation of the physical environmental of the site and also the analysis of the impact of the geological processes on the proposed project. As the result, it is important to civil engineering to understand about history, nature, and the variety behavior of the soil and rock. Geological engineering is the application of the earth sciences to human problem that rlate to Earth and earth system. It is board, interdisciplinary field with many specialty areas such as geotechnical site invstigation for a variety of project, rock and soil slope stability, environmental site characterization and planning, hydrogeology, groundwater stidies and engineering. Natural and man made hazard and invstigation.

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2.3 History of Ayer Hitam, Johor. Ayer Hitam simply means Black Water. A lively town, Ayer Hitam is always bustling with passing vehicles and people who travels north and south. This place is well-known for its ceramic items such as flower vases in an assortment of colours, photo frames, jars, ashtrays, and other home decorative items. For a closer look, you can also watch the potters at work. Aside from quality souvenirs, Ayer Hitam is also dotted with many stalls selling local tidbits. Amongst the famous ones are prawn crackers, steamed corn, tapioca chips, and the all-time must-try “otak-otak”. These food items are fresh and prepacked for you, and sold at reasonable prices. Located in the district of Batu Pahat. Before the advent of the North-South Expressway, Air Hitam was a major route intersection leading to Malacca and Kuala Lumpur going northbound, Johor Bahru and Singapore going southbound, and Kluang and Mersing going eastbound. It was a popular rest stop for many tour buses and travellers between Singapore and Kuala Lumpur. Visitors could find souvenir shops, restaurants and locals peddling to sell their vegetables. The E2 Expressway between Ayer Hitam and Yong Peng flyover is reputed to be haunted. Drivers would feel drowsiness and uneasiness as they drive through the area at night especially when there are no other vehicles nearby and accident rates around the area are much higher than usual, despite the road lacking any high-prone accident bends.

2.4 History of Pulau

Mawar,

Mersing, Johor

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Pulau Mawar is an island and is located in Johor, Malaysia. The estimate terrain elevation above sea level is 35 meters. Pulau Mawar (Rose Island) is located about 26km from Mersing town. It is a 20 mins walk on beach from the main land. It is a small restricted island that is only accessible by foot during low tide. Hiking through its small jungle and mangrove areas can add just a little bit more action onto our trip and provide educational value for the eco-lovers. Access to certain parts of the island requires skillful manoeuvring on big rocks, therefore it may be a bit more difficult for kids and the elderlies. However, the views are certainly worth the effort.

2.5 The Study Of Rock. 2.5.1 Sedimentary Rock 4

Sedimentary rocks are the second major rock group. It is formed from fine constituents of rock usually from mountainous areas which are transported to lower elevation due to certain processes. After traveling at some distance it may get deposited over some existing rocks which on consolidation will result in formation of what as known as sedimentary rocks. Sedimentary rocks cover about 70% of surface of continents but less than 10% of rocks in the earth's crust and most encountered in construction projects. It contains certain metallic and nonmetallic mineral deposits that are important to humanity e.g. deposits of petroleum and coal.

Figure 2.5.1 Formation of Sendimentary RocK

2.5.2 Igneous Rock

Igneous rock (derived from the Latin word ignis meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet's mantle or crust. Typically, the melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition. Solidification into rock occurs either below the surface as intrusive rocks

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or on the surface as extrusive rocks. Igneous rock may form with crystallization to form granular, crystalline rocks, or without crystallization to form natural glasses.

2.5.2.1 Intrusive Rock Intrusive igneous rocks are formed from magma that cools and solidifies within the crust of a planet, surrounded by pre-existing rock (called country rock) the magma cools slowly and, as a result, these rocks are coarse-grained. The mineral grains in such rocks can generally be identified with the naked eye. Intrusive rocks can also be classified according to the shape and size of the intrusive body and its relation to the other formations into which it intrudes. Typical intrusive formations are batholiths, stocks, laccoliths, sills and dikes. When the magma solidifies within the earth's crust, it cools slowly forming coarse textured rocks, such as granite, gabbro, or diorite. The central cores of major mountain ranges consist of intrusive igneous rocks, usually granite. When exposed by erosion, these cores (called batholiths) may occupy huge areas of the Earth's surface.

2.5.2.2 Extrusive Rock Extrusive igneous rocks, also known as volcanic rocks, are formed at the crust's surface as a result of the partial melting of rocks within the mantle and crust. Extrusive igneous rocks cool and solidify quicker than intrusive igneous rocks. They are formed by the cooling of molten magma on the earth's surface. The magma, which is brought to the surface through fissures or volcanic eruptions, solidifies at a faster rate. Hence such rocks are smooth, crystalline and finegrained. Basalt is a common extrusive igneous rock and forms lava flows, lava sheets and lava plateaus. Some kinds of basalt solidify to form long polygonal columns.

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Figure 2.5.2.2 Process of Igneous Rock

2.5.3 Pyroclastic Rocks Pyroclastic rocks or pyroclastics (derived from the Greek: πῦρ, meaning fire; and κλαστός, meaning broken) are clastic rocks composed solely or primarily of volcanic materials. Where the volcanic material has been transported and reworked through mechanical action, such as by wind or water, these rocks are termed volcaniclastic. Commonly associated with unsieved volcanic activity—such as Plinian or krakatoan eruption styles, or phreatomagmatic eruptions—pyroclastic deposits are commonly formed from airborne ash, lapilli and bombs or blocks ejected from the volcano itself, mixed in with shattered country rock. Pyroclastic rocks may be a range of clast sizes, from the largest agglomerates, to very fine ashes and tuffs. Pyroclasts of different sizes are classified as volcanic bombs, lapilli,

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and volcanic ash. Ash is considered to be pyroclastic because it is a fine dust made up of volcanic rock. One of the most spectacular forms of pyroclastic deposit are the ignimbrites, deposits formed by the high-temperature gas-and-ash mix of a pyroclastic flow event.

Identify the type of discontinuity whether fault, joint, cleavage and others

CHAPTER 3 3.0 METHODOLOGY Start

Fall the small rock to know dip direction of the rock

Determine the dip angle using compass. The angle will plus with 90° to get their strike

Determine the persistence where less than 1m is low and more than 20m is high

The aperture / width identify based on their distance 8

The next step is nature of filling. It has 8 characteristics such as 1 for clean, 2 for surface staining and 9 for other sppecify

When we touch a surface of rock, we can identify the surface roughness. We find that rock at Ayer Hitam are rough than Pulau Mawar

Lastly, we classify their water flow and spacing. All data will fill in the table of discontinuity survey data sheet

3.1 Equipment End

Name

: Geology Compass

Function : To measure dip direction and dip angle

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Name

: Digital Rebound Hammer

Function : To determine a rock strength on different types of rock and hardness value.

3.2 Procedure 1. Type. a. See type such as joint, fault and cleavage at the point that we found to determine 2. Dip Angle a. Take the compass and put the down-side compass level with rock slope to find the slope amgle or dip angle b. Make sure the value of a bearing dip angle is in the left side. Read the value that we achieve. The bearing that we achieve is the stepness of the slope. The concept of the dip angle is the radian or bearing from horizontal level to the gradient of the slope rock. 3. Dip Direction a. The dip direction is the maximum angle of inclination downward that a vein or bed makes with a horizontal plane b. To determine the dip direction, take all small rock or material then lay the material to the surface or slope rock. See the direction then the material fall based on gravity. So, the direction is the dip direction.

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c. Draw the dip direction that we achieve d. With compass, level compass to the north direction and see the value of the bearing dip direction. Every strike or dip direction, the value must be determine from north e. The dip direction also can determined by formula:Dip Direction = Strike + 90° f. That is the procedure to determined or measure the dip direction.

4. Strike. a. Strike is he bearing of a horizontal line in the plane of a vein, bed, or fault with respect to the cardinal points of the compass. b. With the dip direction value, we can get the value of strike. c. To determine strike, we can get the formula. Value of strike is 90° anticlockwise from the value of dip direction. d. The formula is :Strike = Dip Direction - 90° e. Same as dip direction can be drawing on the rock and take the compass to get the value or bearing of srike from north direction 5. Persistence a. Measure the length of type. 6. Width a. Measure the width of type (joint) 7. Nature of filling 11

a. Any kind of mineral or water that contains in the joint or fracture 8. Surface roughness a. Determine the surface roughness if the surface rough, smooth, polished or slickenside. 9. Water flow. a. See the point of type that we chosen (joint or fracture) have water flow or not. Fill if water flow (open) or water flow (filled) as description. 10. Spacing a. The distance between joint to another joint near the point.

CHAPTER 4 4.0 RESULT AND DISCUSSIONS AYER HITAM No

Type

Dip angle ( ) 45

strike ( )

Persistence (m)

Apature (mm)

Infilling

Roughness

Water

Fault

Dip direction ( ) 73

1.

336

6

Clean

Rough

Wet

2. 3. 4.

Joint Joint Joint

69 254 81

61 53 54

335 156 351

5 4 6

Others Narrow Clean

Rough Soil Rough

Dry Dry Wet

5. 6.

Joint Slope

78 339

50 68

335 70

7 5

Very narrow Narrow Narrow Very narrow Narrow Narrow

Soil Clean

Smooth Rough

Wet Dry

4.1 Type of Rock. Based on the data and observation that we do in Ayer Hitam, the type of rock that found is igneous rock and sedimentary rock. 4.1.1 Igneous Rock

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4.1.1.1 Intrusive Rocks Intrusive rocks form from molten material (magma) that flows and solidifies underground. These rocks usually have a coarse texture (individual minerals are visible without magnification), because the magma cools slowly underground, allowing crystal growth. Common rock types within the intrusive category are granite and diorite. 4.1.1.2 Extrusive Rocks: Extrusive igneous rocks solidify from molten material that flows over the earth’s surface (lava). Extrusive igneous rocks typically have a fine-grained texture (individual minerals are not visible unless magnified) because the lava cools rapidly when exposed to the atmosphere, preventing crystal growth. Common extrusive rocks are basalt, andesite, and rhyolite.

In construction industry, igneous rock are used in stabilizing and stone pitching the area. The crush rock aggregates of igneous rock also can be used in construction such as in highway engineering. One of the benefits are hard and do not absorb water, that’s why igneous rock are good to be used in the lower courses of building.

4.1.2 Sendimentary Rocks Erosion and deposition play a key part in the formation of sedimentary rocks. Wind, water, ice, and chemicals break down existing rock into sediment that is then transported and deposited by wind, water, and glaciers.

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As sediment accumulates with time (thousands of years) it becomes compacted and cemented (lithified), eventually forming rock. Over a period spanning hundreds of millions of years, oceans, rivers, and great deserts covered Utah and deposited the sediment that has lithified into the sedimentary rocks we see today. Some common sedimentary rocks are shale, sandstone, limestone, and conglomerate. Sedimentary rock also used in construction industry. Example of using sedimentary rock are sedimentary rock are used in building such as sandstone and limestone. This type of also used to be a slabs because its soft enough to cut easily into slabs. Builders also used sandstone and limestone on walls of the buildings. Limestone also are used in making steel and cement.

4.2 Weathering Process Based on the observation of the rock and slope at Ayer Hitam, the weathering processes are occur. Weathering occurs because most of rocks are in equilibrium with higher temperatures and pressure deep within the Earth. If they are exposed to the much lower temperatures and pressures at the surface to the gases in the atmosphere and the elements in water, they become unstable and undergo varius chemical changes and mechanical stresses. The physical weathering process that we found in this area is organic activities. The activities of plants and animals also promote rock disintegration. Burrowing animals such as worms, ants and rodents mechanically mix the soil and loose rock particle. Pressure from growing roots widens cracks and contributes to the rock breakdown

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Example of organic activities

The chemical weathering that have found at Ayer Hitam is oxidation process. We can see clearly that the rock become yellowish color. Oxidation occurs when oxygen in air assisted by water combines with minerals to form oxides. That’s mean the rock at Ayer Hitam contain high iron content and therefore produce rusty, red, yellow and brown rocks and soils. Oxidation process at the rock.

4.3 Geological Structure The geological structure that we found in Ayer Hitam have fault and joint.

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Figure shows the fault at Ayer Hitam. (arrow)

Figure show the joint that have at the rock at Ayer Hitam. 4.4 Schmidt's Hammer Test (Rebound Hammer L-Type) Result: Rebound Hammer 1. 38

2. 58

3. 59

4. 60

5. 61

6. 54

7. 44

8. 62

9. 55

Table 1 At bottom 1. 32

2. 27

3. 30

4. 28

5. 32

6. 28

7. 42

8. 33

9. 36

Table 2 16

To the wall 1. 48

2. 54

3. 56

4. 60

5. 58

6. 53

7. 44

8. 56

9. 58

Table 3

Test is simple and fast and equipments is portable. Test can be undertaken on the surface of block or core samples and does not involve destruction of sample. Index value obtained is rebound number (R) which is a measure of the degree of hardness of rock surface. R 1= 38+58+59+60+61+54+44+62+55 = 54.55 9 R 2 = 32+27+30+28+32+28+42+33+36 = 32 9 R3 = 48+54+56+60+58+53+44+56+58 = 54.11 9 4.5 Slope Failure Based on the great circle that we have draw, type of failure that have in Ayer Hitam is only wedge failure. Wedge failure: (Joint 1, Joint 2)

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JOINT

DIP DIRECTION ( )

DIP ANGLE ( )

Joint 1

73

45

Joint 2

69

61

PULAU MAWAR No

Type

1. 2.

Figure show wedge failure at Ayer Hitam. Dip angle ( ) 313

strike ( )

Persistence (m)

Apature (mm)

Infilling

Roughness

Water

Fault

Dip direction ( ) 37

65

10

Clean

Rough

Dry

Joint

60

324

48

9

Very Narrow Very Narrow

Others

Rough

Dry

18

3. 4.

Joint Joint

34 21

304 302

78 40

2 2.5

5.

Joint

23

290

41

2

6.

Slope

112

26

79

2

Narrow Moderately Wide Moderately Wide Narrow

Clean Clean

Rough Rough

Dry Dry

Clean

Rough

Dry

Clean

Rough

Dry

4.6 Type Of Rock Rock or stone is a naturally occurring substance, a solid aggregate of one or more minerals or mineraloids. For example, granite, a common rock, is a combination of the minerals quartz, feldspar and biotite. The Earth's outer solid layer, the lithosphere, is made of rock. Rock has been used by mankind throughout history. The minerals and metals found in rocks have been essential to human civilization. Three major groups of rocks are defined: igneous, sedimentary, and metamorphic. The scientific study of rocks is called petrology, which is an essential component of geology. From the geology trip in Pulau Mawar, the type of rock there is pyroclastic rocks. Pyroclastic rocks are volcaniclastic rocks formed by accumulation of pyroclasts (fragments) during explosive eruption.

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Rock from Pulau Mawar : Pyroclastic rocks

A pyroclastic texture shows a mixture of rock fragments, pumice, and volcanic ash. The ash is very fine grained, so only the rock fragments and pumice are identifiable. A rock with a pyroclastic texture is termed a tuff if the largest fragments are less than 2.5 inches long, a volcanic breccia if the fragments are larger.

4.7 Weathering Pulau Mawar has a rock which is different from Ayer Hitam, that is because of several factors. Besides that, rock from Pulau Mawar also have low strength if compered rock from Ayer Hitam. First, it is because surrounding factors such as, the rock from Pulau Mawar having a weathering proses. Weathering is a general term describing all changes that result from the exposure of rock materials to the atmosphere. It is one of the most important geologic processes that leads to the disintegration or decomposition of geologic deposits. There are two classification of weathering processes which is physical weathering and chemical weathering. Physical weathering is a term used in science that refers to the geological process of rocks breaking apart without changing their chemical composition. Over time, movements of the Earth and environment can break apart rock formations, causing physical weathering. In among

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physical weathering that have in Pulau Mawar such as, frost action, saline crystal growth, organic activities.

Condition of rock in Pulau Mawar

Weathering occurs because most rocks are in equilibrium with higher temperatures and pressure deep within the Earth. Rocks which are deeply buried lies in a different environment physically and chemically than those exposed on the earth's surface and therefore changes will take place to accommodate these new conditions. If they are exposed to the much lower temperatures and pressures at the surface, to the gases in the atmosphere, and to the elements in water, they become unstable and undergo various chemical changes and mechanical stresses.

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The rock having Frost action, that occur when water freezer and expands within crack in rock enlarging them.

As a result, the solid bedrock breaks down into loose, decomposed products. Rock fragments produced by weathering are removed by erosion and the general term for both weathering and erosion is known as denudation. If we can see at figure 3, the picture show the rock from Pulau Mawar have a diffrerent surface of rock if compared the rock from Ayer Hitam.

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Figure 3 : That is rock from Pulau Mawar The rock from Pulau Mawar also having salt weathering. Salt weathering is a form of mechanical or physical weathering of rock. No chemical alteration of rock constituents is involved in salt weathering. The salt derives from an external source (capillary rising ground water, eolian origin, sea water along rocky coasts, atmospheric pollution). Salt weathering is favoured by dry conditions, such as are found in warm and cold (arctic) arid climates. Salt weathering (salt damage, salt decay) also occurs on buildings and monuments in arid climates as well as under dry microclimatic conditions in humid climates. Corrosion by sea water (marine corrosion, aqueous corrosion) is not a mechanical but an electrochemical process. One of the salt weathering, that we can see is honeycomb happen at rock fromPulau Mawar.

Honeycomb

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Combination of moisture and salts (halite, gypsum, etc.) has been found to cause scaling or decay of building stones.

The Stresses due to growth of salt can cause the rock to break apart physically. This process is particularly effective in porous rocks subjected to alternate wetting and drying. Further

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disintegration of rock may occur due to expansion of salt crystals which have grown in former voids.

From observation at Pulau Mawar, it also has organic activities. Organic activity, with regards to weathering and erosion, is defined as the activity of plants and animals that cause physical weathering of disintegration. This activity includes tree roots growing into crevices, lichens growing on rocks and animals burrowing into dirt.

Tree roots growing into crevices

The activities of plants and animals also promote rock disintegration and burrowing animals such as worms, ants and rodents mechanically mix the soil and loose rock particle. Then pressure from growing roots widens cracks and contributes to the rock breakdown.

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The stone form Pulau Mawar also having chemical weathering. Chemical weathering reactions produced minerals of increased volume. The Decomposition produces a chemical breakdown of rocks, which may destroy the original minerals and produce new ones while expansion will result in the physical disintegration or break up of rock. Common processes of chemical weathering reactions are, oxidation hydration, hydrolysis and dissolution.

Oxidation

From this picture, we can see oxidation happen to the rock. Oxidation occurs when oxygen in air assisted by water combines with minerals to form oxides. The oxidation normally occurs to rock or minerals such as olivine pyroxene and amphibole that contain high iron content and therefore produce rusty, red, yellow and brown rocks and soils.

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From this picture, it also showing of chemical weathering reaction from hydration. Hydration is the process whereby mineral combines with water to form a hydrated mineral especially hydrated silicates and hydroxides.

The most important of aspect of hydration is that the hydrated mineral is larger in volume than the parent mineral to exert pressure on its surrounding space and contribute to rock disintegration.

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weathering of feldspar

The rock from Pulau Mawar also have weathering reaction like hydrolysis. Hydrolysis is the chemical union of water and a mineral. This is the reaction of mineral with water to produce a new mineral or minerals.

An example is the weathering of feldspar by reacting with water to form clay. Feldspar is an abundant mineral in a great many igneous, sedimentary, and metamorphic rocks, so it is important to understand how feldspars weather and decompose into clay minerals, which form the most abundant sedimentary rock, shale and the rock increases in volume due to the reaction of the Felds phatic minerals by hydrolysis process.

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Next, we also found there spheroidal weathering on a rock from Pulau Mawar. In this type of weathering, a rounded shape is produced. This shape is caused by weathering that attacks an exposed rock from all sides at once.

Rock with rounded shape

Argular boulder

Corner s and edges of boulde r decom pose

Ronde d bould er

Therefore, decomposition is more rapid along corners and edges of the rock. As the decomposed material falls off, the corners become rounded and the block eventually is reduced to an ellipsoid or a sphere. Exfoliation is a special type of spheroidal weathering, where the rocks break apart by separation along a series of layer.

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4.8 Geology Structures Structural geology is the study of the processes that result in the formation of geologic structures and how these structures affect rocks. The rocks comprising the crust respond to such stresses by undergoing changes of shape (strain), therefore various geological structures are developed which provide a record of type of deformation. The Compressional, tensional and shearing forces acting on rocks may cause them to form, fold, fractures and joints. So, from our view at Pulau Mawar has geology structures such as joint. In geology, the term joint refers to a fracture in rock where the displacement associated with the opening of the fracture is greater than the displacement due to lateral movement in the plane of the fracture (up, down or sideways) of one side relative to the other. Typically, there is little to no lateral movement across joints. This makes joints different from a fault which is defined as a fracture in rock in which one side slides laterally past the other with a displacement that is greater than the separation between the blocks on either side of the fracture. Joints normally have a regular spacing related to either the mechanical properties of the individual rock or the thickness of the layer involved. Joints generally occur as sets, with each set consisting of joints sub-parallel to each other. Joints form in solid, hard rock that is stretched such that its brittle strength is exceeded (the point at which it breaks). When this happens the rock fractures in a plane parallel to the maximum principal stress and perpendicular to the minimum principal stress (the direction in which the rock is being stretched). This leads to the development of a single sub-parallel joint set. Continued deformation may lead to development of one or more additional joint sets. The presence of the first set strongly affects the stress orientation in the rock layer, often causing subsequent sets to form at a high angle to the first set. Joint sets are commonly observed to have relatively constant spacing, which is roughly proportional to the thickness of the layer.

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The picture show wedge failure appearing in Pulau Mawar. Wedge failure of rock slope results when rock mass slides along two intersecting discontinuities, both of which dip out of the cut slope at an oblique angle to the cut face, thus forming a wedge-shaped block. Wedge failure can occur in rock mass with two or more sets of discontinuities whose lines of intersection are approximately perpendicular to the strike of the slope and dip towards the plane of the slope. This mode of failure requires that the dip angle of at least one joint intersect is greater than the

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friction angle of the joint surfaces and that the line of joint intersection intersects the plane of the slope. 4.9 Result Obtained Related To Civil Engineering Or Construction Rocks cover the earth's surface, including what is below or near human-made structures. With rocks everywhere, breaking rocks can be hazardous and potentially disastrous to people. Students are introduced to three types of material stress related to rocks: compressional, torsional and shear. They learn about rock types (sedimentary, igneous and metamorphic), and about the occurrence of stresses and weathering in nature, including physical, chemical and biological weathering. Geotechnical engineers study rocks in the earth's crust. They conduct tests and simulations to predict volcanoes, earthquakes and rockslides. To avoid potential disasters that might occur if rocks fail, engineers routinely apply their understanding of rocks and soils prior to the construction of complex and costly structures such as airports, roads, dams, skyscrapers and tunnels. They identify underground rock types and predict their behavior under stress, as well as determine the best way to excavate them as part of the construction process. So, from the task that are given, our group agreed, that important to us, to know about geology of rock. It can help us to know type of rock, strength of rock before any construction have built. For example, rock from Pulau Mawar not suitable to use as construction materials because it’s have lowest of strength. Besides that rocks are extremely important in terms of their properties of stability and strength as a geological material on which construction foundations are made and historically as building material from which important and monumental buildings are made. Rock used for wall, building, and bridge construction over history until recent times is generally cut from natural rocks. So, important to us know type of rock and properties of rock. Rock from Ayer Hitam have a good strength if compared with rock from Pulau Mawar. That because several factors. Both of rock are taken from two different place. Rock from Pulau Mawar have more expose to weathering process like, saline crystal growth, frost action and others. Therefore, it has a lower strength, lower density, lower stability.

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CHAPTER 5 5.0

QUESTION

1. The Name of rock particularly at Pulau Mawar and Ayer Hitam. a) Pulau Mawar The rock in Pulau Mawar are categories Sedimentary rocks. It is formed from fine constituents of rock usually from mountainous areas which are transported to lower elavation due to certain processes. Classification of Sedimentary Rock: Detrital Sedimentary Rock Classic Texture

Sediment Name Sand (feldspar is present the rock is called Arkose)

Rock Name

Akose Sandstone

Medium (1/16mm to 2mm)

Mud

Shale

Mud

Siltstone

Very fine (less than 1/256mm)

Fine (1/16mm to 1/256mm)

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b) Ayer Hitam The rock in Ayer Hitam are categories an Igeneous Rock. They are formed when volcanoes erupt, causing the magma to rise above the earth’s surface. When magma appears above the earth as lava , its cools above the ground. They are called Extrusive or Volcanic.

Classification of Igneous Rock: Texture

Chemical Composition

Dominant Minerals

Name of Rock

Phaneritic (coarse-grained)

Basaltic (Mafic)

Pyroxene Calciumrich plagioclase feldspar

Gabbro

Aphanitic (finegrained)

Basaltic (Mafic)

Pyroxene Calciumrich plagioclase feldspar.

Basalt

Aphanitic (fine-grained)

Andesitic (intermediate)

Amphibole Sodium and calcium rich plagioclase feldspar.

Andesite

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2. Parents materials of rock at Pulau Mawar and Ayer Hitam. Parent materials that are predominantly composed of consolidated rock are formed residual parent material. The consolidated rocks consist of igneous, sedimentary and methamorphic rock. a) Pulau Mawar Parent rock at Pulau Mawar are formed from fine constituents of rock usually from mountanious area which are transported to lower elevation due to certain process. After travelling at some distance it will deposition and cementation of that material at the earth’s surface and within bodies of water. The formation are known as sedimentary rocks.

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Weathering process from the exposure of rock material: i. Frost Wedging

ii.

The rock at Pulau Mawar are freezing and thawig of water in cracks.

Mechanical Exfoliation

Rock expand and cracks as overlaying rocks are removed by erosion.

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iii.

Organic activities

Powerful tree roots grow in rock fracture iv.

Abrasion

-

Rock collide in a moving current They also grid away at exposed rock, forming patholes in bedrock

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b) Ayer Hitam Parent rock at Ayer Hitam are formed from the eruption of volcanoes, fissures or cracks in the erath’s crust. Some materials will be emitted with gasses into atmosphere, where they cool quickly and fall to the earth as volcanic ash and dust. Volcanic action is a lava emitted from within the earth as a molten stream over the surface until it solidifies.They also called as Extrusive Igneous rock. Extrusive rocks are generally distinguished by their usual fine-grained texture.

3. Geological structure available at Pulau Mawar and Ayer Hitam. a) Pulau Mawar

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Types

Fracture Normal Fault

Fold Overturned anticlined and syncline.

Joints Joint in granite.

Lateral fault

Syncline fold

Joint in folded stratum

Normal Fault

Anticline fold

Join in folded stratum

b) Ayer Hitam

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Types

Fracture

Fold

Joint

Normal Fault

Anticline Fold

Joint in granite.

Lateral Fault

Anticline Fold

Parallel slope joint.

Normal fault

Anticline Fold

Parallel slope joint.

Reverse Fault

Syncline Fold

Joint in granite.

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4.

State the rock testing to measure joint compressive strenght of rock from surface. i.

Shear Test The test is done on rock sample and is important in project involving excavation of fracture and jointed rock. Shear test is normally conducted on weakness planes in rock (joint, fault and bedding plane). Strength parameters of discontinuity obtained from shear test include cohesion, basic friction, peak shear strength and residual shear strength. Surface texture and roughness vary between planes and type of rock. Value of the parameters is the values represent the particular discontinuity tested. The average basic friction angles for joint in rocks, under dry condition, are between 30º (siltstone & slate) and 40º (limestone, basalt and dolerite). When the dicontinuities are critical to a structure, in situ shear test are necessary.

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5.

Explain types of rock slope stabilization which may be applied at Ayer Hitam and Pulau Mawar. 

Plane failure Slope failure represent at Pulau Mawar is a plane failure. The surface in planar failures are resulted by structural discontinuities like bedding planes, faults or the interface between weathered rock and the underlaying bedrock. This kind of failure leads to sliding action along the failure surface.



Wedges Failure This kind of failure causes a rock mass to slide along two intersecting discontinuites. This mood of failure needs the deep angle of at least one joint intersection to be greater than the angle of friction of the joint surface. The lithology for he development of wedges failure includes inclined bedding, foliation and well defined cleavage.

Stabilization of slopes is very important and justified the unstable slopes might be hazardous. There are some methods that reduce slope failure and support system to provide stability: i.

Excavation and removal the upper slope. The stability of slope types depends on height of slope.

ii.

Installed the rock bolts across failure surfaces. This can be used for smaller failure planes or small rock masses.

iii.

Retaining walls This are usually reinforced concrete structure constructed at the toe of the slopes. This give a kind of passive resistance against sliding.

iv.

Fences These can be used to intercept rocks rolling down slope with an angle less than 40 degrees.

v.

Cables

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Installed the cables across failure surfaces to increase its strenght. These can be used large rocks as cables have higher strenght than rock bolts.

CHAPTER 6 6.0 CONCLUSION In conclusion, rock types, geology structure and orientation are strongly controlled rock slope stability. There are required to acquire a thorough understanding of these parameters mentioned. The field trip really helped our group to learn some of the stuff that we studied during this course being able to see some real examples and having them explained to us. Next,

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this field trip also help us to determined the 3 categories of rock which is igneous rock, sedimentary rock and metamorphic rock. Based on the data and observation that we do in Ayer Hitam, the type of rock that found is igneous rock and sedimentary rock. Based on result also we can see that the water condition at there is balance some part are dry and some of the joint are wet. As an example on joint 4 dip direction that we get is 81 dip angle 54 and strike 351. The apature is very narrow and infilling clean. It also rough and wet condition. When we are there we need to take 5samples of rock to determine the strength. From our previous lab,we do the testing on rock strength and we get the value for Point Load Index Strength Is(Mpa) for Ayer Hitam is more than >5 Mpa compare to Pulau Mawar which is less than