btech l2

STAKING-OUT OR SETTING OUT

The process of relocating the point of boundaries and property line of the site where the building is to be constructed

STEPS TO STAKING 1

1. Measure the required setback from the front corner monuments. Drive two stakes and stretch a string between them to represent the front building line.

STEPS TO STAKING 2

Measure the required side setback from one of the side lot lines along the front building line. Drive stake A which will represent the first corner of the building. From Stake A, measure the width of the building and mark with stake B to obtain the other front corner.

STEPS TO STAKING 3

Estimate right angles from stakes A and B and measure the length of the building. In those two points, drive two temporary stakes C and D, which will mark the rear corners of the building. C-D should be equal to A-B. Draw lines along the diagonals A-D and B-C and ensure that these are equal. Transfer the building lines to the batter boards

STEPS TO STAKING 4

Draw lines along the diagonals A-D and B-C and ensure that these are equal.

STEPS TO STAKING 5

Transfer the building lines to the batter boards

STAKES

- are wooden sticks used as posts sharpened at one end driven into the ground to serve as boundaries or supports of the batter boards.

STRINGS

- are either plastic cords or galvanized wires strung across batter boards and used to indicate the outline of the building wall and foundation.

BATTER BOARDS

– wood sticks or boards nailed horizontally at the stake which serve as the horizontal plane where the reference point of the building measurements are established- horizontal boards that establish the height of the footing trenches and foundations or establish the height of the finish floor levels.

LEVELING

– done with a line level or carpenter’s level, or with a transit. The height of the batter boards may be level with or a little higher than the top of the finished foundation

SPIRIT LEVEL

- an instrument or tool capable of vertical and horizontal line check.

PLUMB BOB

- a weight attached to a string, used for a vertical line check.

PLASTIC HOSE FILLED WITH WATER

– method of leveling batter boards horizontally without transit

PYTHAGOREAN THEOREM’S 3-4-5 METHOD

A manual method of squaring the corners of building lines in staking.

PYTHAGOREAN THEOREM’S 3-4-5 METHOD:

A practical method for creating a precise 90-degree angle, often used in construction and carpentry.

Application of the 3-4-5 method 1.

Begin at an origin point. Measure 3 units along a reference line and mark this point

Application of the 3-4-5 method 2.

From the origin point, measure 4 units perpendicular to the first line and mark this point

Application of the 3-4-5 method 3.

Measure the distance between the two marked points; it should be 5 units. If this measurement is correct, the angle formed between the two lines is a right angle.

3-4-5 METHOD

This method is particularly useful for laying foundations, aligning walls, and verifying the perpendicularity of structural elements. It is easy to implement and only requires basic tools, such as a tape measure.

Excavation

• Refers to the process of removing soil or rock from its original location, typically in preparation for constructing foundations, basements, and underground utility lines, and for grading of the ground surface.

backfill/grading fill

• Excavated material required for blank is stockpiled on the site for subsequent use.

1. Open Excavations

• Refers to large (and often deep) excavations, such as for a basement.

2. Trenches

• Refers to long, narrow excavations, such as for footings, under a wall or utility pipes.

3. Pits

• Excavations for the footing of an individual column, elevator shaft, & so on

3 types of excavation

open excavation

trenches

pits

Leveling and Grading

• Involves moving earth from one location of the site to another and changing the existing land surface to the desired finished surface configuration as per the site plan and drainage plan.

leveling and grading

• A processes that change land elevation and slope by filling in low spots and shaving off high spots

1. Rough Grading

Done along with excavations for foundations, basements, and utility trenches.

Finish Grading

Generally done towards the end of the project as per the landscape design.

Supports for Open Excavations

• The simplest excavation support system consists of providing adequate slope in the excavated (cut) face so that it is able to support itself.

• Maximum slope must be determined from soil investigations.

• Can be uniformly sloped or stair-stepped, called Benched Excavation

Benched Excavation

uniformly sloped or stair-stepped

Support System for restricted or tight site areas

utilizes vertical cuts that can be removed after construction or permanently placed.

supports for open excavations

• Cohesive soils with shallow vertical cuts (1.0 meter and less) may be possible without any support system. Deeper vertical cuts must be provided with a support system.

Stabilizing the soil

is the process of compacting the soil on which the structure will rest.

supports for open excavations

• The protection of adjoining structures is a law that provides that any person making an excavation is responsible for resulting damage to adjoining property

Shoring

A process of transferring a portion of the load of the wall to temporary footings and done when the excavation does not go much below the adjoining footings and when the material is fairly solid

a) Sheet piles

which are timber, steel, or pre-cast planks driven side by side to retain earth and prevent water from seeping into the excavation

b) Wales

or continuous horizontal beams which tie the sheet piles in place

c) Soldier Piles,

which are steel H-sections driven vertically into the ground to support

d) Lagging

or heavy timber planks joined together horizontally to retain the face of an excavation.

e) Cross Bracing

or rakers are diagonals which support the wales and soldier piles bearing on heel blocks or footings.

f) Tiebacks

secured to rock or soil anchors are resorted to when cross bracing or rakers would interfere with the excavation procedure.

Support System for Restricted, Tight, Large Site Areas

Sheet Piles Cantilevered Soldier Piles Anchored Soldier Piles Contiguous Bored Concrete Piles

SHEET PILES

• Consist of individual steel sections that interlock with each other on both sides.

• Available in many cross-sectional profiles: - Z-section is most commonly used.

• Driven into the ground one by one using either hydraulic hammers or vibrators

SHEET PILES

• Deeper excavation (generally greater than 4.5 meters) – sheet piles are braced with horizontal or inclined braces or anchored with tiebacks

CANTILEVERED SOLDIER PILES

• An alternative to Sheet Piles excavation support.

• H-shaped steel columns (called soldier piles or H-piles) are placed in the ground - pre-drilled circular holes with approximately 6-8 ft (1.8m to 2.4m) on center.

CANTILEVERED SOLDIER PILES

• An alternative to Sheet Pile excavation support.

• H-shaped steel columns (called soldier piles or H-piles) are placed in the ground - pre-drilled circular holes with approximately 6-8 ft (1.8m to 2.4m) on center

CANTILEVERED SOLDIER PILES

• An alternative to Sheet Pile excavation support.

• H-shaped steel columns (called soldier piles or H-piles) are placed in the ground - pre-drilled circular holes with approximately 6-8 ft (1.8m to 2.4m) on center.

ANCHORED SOLDIER PILES

• For deeper excavations, an anchored soldier pile system is employed.

• Similar to Cantilevered except that the piles are tied back (anchored) into the ground.

• Commonly used vertical support members for this system consist of 2 steel channels with a space between them.

Tieback anchor detail in an anchored soldier pile support system

with WWR and Shotcrete.

Section though an anchored soldier pile support system

with lumber lagging.

3. ANCHORED SOLDIER PILES

• For deeper excavations, an anchored soldier pile system is employed. • Similar to Cantilevered except that the piles are tied back (anchored) into the ground. • Commonly used vertical support members for this system consist of 2 steel channels with a space between them.

CONTIGUOUS BORED CONCRETE PILES

• In situations where the (deep) excavation is close to an adjacent building or property line.

• Closely spaced reinforced concrete piles made by screwing an auger into the ground. (the auger called a continuous flight auger, has a hollow stem in the middle where concrete is pumped down)

Dewatering

Refers to the process of lowering a water table or preventing an excavation from filling with groundwater. It is accomplished by driving perforated tubes called wellpoints into the ground to collect water from the surrounding area so it can be pumped away

dewatering

It is important to keep excavations free from Groundwater.

dewatering

Disadvantage/Effects: Impedes further excavation, is unsafe for workers, and is harmful to equipment and machines

2 Parts of Groundwater Control a)

Preventing surface water from entering the excavation through runoff.

2 parts of groundwater control

b) Draining the soil around the excavations so that the groundwater level falls below the elevation of the proposed excavation.

1. Sump Pump

• Consists of constructing pits (called sumps) where its bottom is located below the final elevation of the excavation.

• Water is lifted by automatic pumps and discharged away from the building site.

2. Well Points

• Uses forced suction to extract water by sinking a number of vertical pipes with a screened end at the bottom (called well points) around the perimeter of the excavation.

• Caution: Can lower the water table and may affect the adjoining buildings, and can cause consolidation and settling of foundations.

SLOPE PROTECTION AND RETAINING STRUCTURES

1. BENCHED EXCAVATION

2. SOIL BINDERS

BENCHED EXCAVATION

The need for stabilizing a sloping ground can be reduced by diverting the runoff at the top of the slope or by creating a series of terraces to reduce the velocity of the runoff.

2. SOIL BINDERS

A natural means of stabilization; plant materials that inhibit or prevent erosion by providing a ground cover and forming a dense network of roots that bind the soil

RIPRAP

- is a layer of irregularly broken and randomly sized stones placed on the slope of an embankment.

riprap

- a constructed layer or facing of stone, placed to prevent erosion, scour or sloughing of a structure or embankment.

riprap

- The term is also frequently defined as the stone used to construct such a lining

RIPRAP

- a special class of very large aggregate. blank gradations range in diameter from 50mm (2 inches) to 1148mm (42 inches). Because riprap is subject to significant energy, it is important that it be sound and free from defects or entrained substances such as soil, shale, or organic materials.

riprap

Resistance of blank to displacement of moving water is a function of the weight, size, and shape of the stone, the geometry of the channel or bank it is protecting, and the filter blanket over which the riprap is placed.

GABION

Wire-enclosed Riprap

- are modular wire mesh containers filled with stones or rock, widely used for erosion control, retaining walls, and river protection.

gabion

- Wrapping the riprap enables the use of smaller rocks for the same resistance to displacement by water energy as larger unwrapped riprap

GABION

- is particularly advantageous in areas inaccessible to trucks or large construction equipment.

- Wire baskets also allow steeper (i.e., vertical) channel linings to be constructed.

- blank baskets or mattresses can be made from commercially available wire units or from available wire fencing material or may be fabricated from No. 9 or No. 12 galvanized wire

GEOSYNTHETICS

- Construction materials consisting of synthetic components made for use with or within earth materials generally are referred to as geosynthetics. Geosynthetics can be further categorized into the following components

- Geotextiles - Geomembranes - Geocomposites - Geonets - Geocell

CRIBBING

- is a cellular framework of squared steel, concrete, or timber members, assembled in layers at right angles, and filled with earth or stones.

1. GRAVITY RETAINING WALL

- Gravity retaining walls use the gravitational force of their own weight to resist the lateral earth pressure from the soil behind them, which prevents toppling and sliding. They are the simplest and earliest recorded type of retaining wall

T-TYPE AND L-TYPE CANTILEVER RETAINING WALLS

-limited to a height of 20’ (6 M); beyond this height a counterfort wall is employed.

- Commonly constructed from reinforced concrete, T-TYPE cantilever retaining walls are engineered to withstand lateral soil pressure and are suitable for higher retaining requirements.

- L-TYPE is used when the wall abuts a property line or other obstruction

1. COUNTERFORT RETAINING WALL

utilizes triangular-shaped cross walls to stiffen the vertical slab and add weight to the base. The counterforts are spaced at equal intervals equal to one-half the wall height

1. COUNTERFORT RETAINING WALL

- is a type of counterfort wall. These types of retaining wall are constructed on the face of the wall rather than within the backfill. Buttress walls are rarely used since their exposed buttressed design consumes space and detracts from their look. Typically made of concrete, the buttress retaining wall is suitable for sites with heavy loads and poor soil conditions