describe difference types of shoring systems and their suitability for various situation

 Shoring Systems

Definition (1 mark)

Shoring is a temporary structure used to support unsafe walls, structures, or excavations to prevent collapse during construction or repair work.

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Types of Shoring Systems and Their Suitability (2.5–3 marks)

1. Raking Shoring

• Inclined supports (rakers) are placed against a wall.
• Transfers load from the wall to the ground.

👉 Suitability:

• When a wall is weak or bulging
• During repair of existing walls
• Where ground space is available for rakers

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2. Flying Shoring

• Horizontal supports provided between two parallel walls.
• No support from the ground.

👉 Suitability:

• When adjacent buildings need support
• When the space between buildings must be kept clear (e.g., roads, passages)

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3. Dead Shoring

• Vertical supports (props) are used to carry loads.
• Used to transfer load from upper parts while lower parts are altered.

👉 Suitability:

• During removal of lower walls or foundations
• For making openings in walls
• When rebuilding or altering structural elements

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Key Concept

• Shoring systems are selected based on type of structure, available space, and nature of work.

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Conclusion (1 mark)

Different types of shoring—raking, flying, and dead shoring—are used according to site conditions to ensure safety and stability of structures during construction or repair.

Describe the different tyes of walls based on their functions

Describe the different tyes of walls based on their functions

Walls can be classified based on their functions (purpose in a building). Here are the main types explained clearly:

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1. Load-Bearing Wall

This type of wall carries the weight of the structure (roof, floors, slabs) and transfers it to the foundation.

• Essential structural element
• Usually thicker and stronger
• Common in traditional construction

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2. Non-Load Bearing Wall

This wall does not support any structural load except its own weight.

• Used mainly for partitioning spaces
• Can be removed or modified without affecting the building structure
• Example: partition walls in offices

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3. Partition Wall

A wall used to divide a large space into smaller rooms.

• Lightweight and thin
• Made from materials like wood, glass, or bricks
• No structural role

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4. Retaining Wall

This wall is used to hold back soil or earth on one side.

• Common in hilly areas and road construction
• Prevents soil erosion and landslides
• Designed to resist lateral pressure

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5. Boundary Wall (Compound Wall)

A wall built to enclose a property or land area.

• Provides security and privacy
• Usually constructed around houses, schools, or industries

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6. Shear Wall

A structural wall designed to resist lateral forces like wind and earthquakes.

• Very important in high-rise buildings
• Adds stability and stiffness to the structure

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7. Curtain Wall

An outer wall that does not carry any load except its own weight.

• Common in modern buildings with glass facades
• Attached to the frame of the building

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8. Parapet Wall

A low-height wall constructed at the edge of roofs, balconies, or terraces.

• Provides safety (prevents falling)
• Also improves appearance

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9. Fire Wall

A wall built to prevent the spread of fire between sections of a building.

• Made of fire-resistant materials
• Common in factories and large buildings

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10. Dwarf Wall

A short wall (low height) used for support or decoration.

• Often used below windows or for fencing

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Conclusion

Different types of walls are used in construction depending on their function such as supporting loads, dividing spaces, ensuring safety, or providing protection. Each type plays a specific role in making a structure stable, safe, and functional.

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Explain the purposes of surveying what are the uses of theodolite describe various sources of errors in theodolite surveying

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## Surveying and Theodolite

Purpose of Surveying (2.5–3 marks)

Surveying is carried out for the following purposes:

1. Preparation of Maps and Plans

• To represent natural and artificial features on maps.

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2. Determination of Relative Positions

• To locate points on the ground with respect to each other.

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3. Construction Work

• For setting out roads, railways, buildings, bridges, etc.

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4. Boundary Determination

• To fix property lines and land boundaries.

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5. Calculation of Area and Volume

• Used in earthwork estimation and land measurement.

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6. Route Alignment

• To select suitable routes for engineering projects.

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Uses of Theodolite (2.5–3 marks)

A theodolite is mainly used for precise measurement of angles and alignment work:

1. Measurement of Horizontal Angles

• Used in triangulation and traverse surveys.

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2. Measurement of Vertical Angles

• Used in height determination and trigonometric levelling.

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3. Alignment of Points

• Used for prolonging straight lines and setting out works.

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4. Trigonometric Levelling

• Used to determine elevation of inaccessible points.

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5. Setting Out Engineering Works

• Used in construction for accurate positioning.

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Sources of Errors in Theodolite Surveying (3–4 marks)

Errors in theodolite surveying arise due to the following:

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1. Instrumental Errors

• Imperfect adjustment of the instrument
• Eccentricity of verniers and circles
• Collimation error (line of sight not horizontal)

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2. Personal Errors

• Improper centering or leveling
• Inaccurate reading of vernier
• Parallax due to improper focusing

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3. Natural Errors

• Wind affecting instrument stability
• Temperature variations causing expansion
• Refraction and curvature of the earth

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Key Concept

• Errors can be minimized by proper adjustment, careful observation, and repeated measurements.

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Conclusion (1 mark)

Surveying serves essential purposes in mapping and construction, while the theodolite is a vital instrument for precise angle measurement, though care must be taken to reduce instrumental, personal, and natural errors for accurate results.

Define close traverse. Why checks are necessary in closed traverse

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## Closed Traverse

Definition (1 mark)

A closed traverse is a type of traverse in which the series of survey lines forms a closed polygon, either by returning to the starting point or by closing on another known point.

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Why Checks are Necessary in Closed Traverse (2.5–3 marks)

Checks are necessary in a closed traverse for the following reasons:

1. Detection of Errors

• Helps to identify errors in angle and distance measurements.

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2. Angular Check

• The sum of interior angles should satisfy the condition:

  (2n - 4) \times 90^\circ \quad \text{(for n sides)}

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3. Linear (Closing) Check

• The traverse should close properly, meaning the final point should coincide with the starting point.
• Any gap is called closing error.

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4. Accuracy Verification

• Ensures that the survey work is reliable and accurate.

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5. Adjustment of Errors

• Errors can be distributed and corrected using methods like Bowditch rule.

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Key Concept

• A closed traverse allows both angular and linear checks, which are not possible in open traverse.

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Conclusion (1 mark)

Checks are essential in a closed traverse to detect, evaluate, and adjust errors, ensuring accuracy and reliability of the survey results.

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State the main principles of plane table survey also write its advantages and disadvantage

 

## Plane Table Survey

Main Principles of Plane Table Survey (2.5–3 marks)

The plane table survey is based on the following principles:

1. Parallelism (Orientation)

• The position of objects on the map is obtained by drawing lines parallel to the directions of objects on the ground.
• Proper orientation ensures that plotted lines represent true ground directions.

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2. Radiation Principle

• From a single station, lines are drawn to various points.
• The distances are measured and plotted to scale.

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3. Intersection Principle

• The position of a point is fixed by the intersection of two rays drawn from two known stations.

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4. Traversing Principle

• A series of connected points are plotted by moving the table from one station to another.

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Advantages of Plane Table Survey (2–3 marks)

• Fieldwork and plotting are done simultaneously → saves time
• No need for field book → reduces recording errors
• Errors can be detected and corrected on the spot
• Simple equipment and easy to use
• Suitable for small-scale and detailed surveys

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Disadvantages of Plane Table Survey (2–3 marks)

• Not suitable for high precision work
• Cannot be used in bad weather (rain, wind)
• Requires clear visibility of points
• Equipment is bulky and difficult to handle
• Not suitable for large areas

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Conclusion (1 mark)

Plane table surveying is based on graphical representation and orientation principles, offering quick and simple fieldwork, but it is limited in accuracy and weather conditions.

Method of contouring

 

## Methods of Contouring

Definition (1 mark)

Contouring is the process of determining the elevation of points on the ground and representing them by contour lines on a map.

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Methods of Contouring (2.5–3 marks)

There are two main methods:

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1. Direct Method

• Contours are traced directly on the ground.
• Points of equal elevation are located using a levelling instrument.
• These points are then plotted to form contour lines.

👉 Features:

• Highly accurate
• Time-consuming and costly

👉 Example: Used for small areas where high precision is required.

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2. Indirect Method

• Elevations of selected points are measured.
• Contours are drawn by interpolation between these points.

👉 Common techniques:

• Method of squares (grid method)
• Cross-section method
• Radial line method

👉 Features:

• Faster and economical
• Less accurate than direct method

👉 Example: Used in large area surveys like road or railway projects.

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Key Concept

• Direct method → accurate but slow
• Indirect method → faster but involves estimation (interpolation)

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Conclusion (1 mark)

Contouring can be done by direct or indirect methods, where the choice depends on accuracy required, area size, and available time, with indirect methods being more commonly used in practice.