Chapter IIIa construct foundation blockthi cong mong khoi EN

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ARTIFICIAL WORKS F2
GROUP 3:

LÊ VĂN SƠN
ĐỒNG THỊ BÍCH LOAN


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CHAPTER IIIa – CONSTRUCTION OF THE SPREAD
FOOTING ON NATURAL GROUND


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MAIN CONTENTS
 Construction methods for foundation pit
 Bottom foundation treatment
 Concreting spread footing
 Fill up the foundation pit
 Organize spread footing construction

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CONSTRUCT FOUNDATION PIT BY BARE EXCAVATION METHOD
Construction
methods for
foundation pit

Bottom foundation
treatment

Concreting spread
footing

 Ditch with manual-pressed bulldozer :
 Scope of application: The foundation is located on steep terrain, especially the foundation. The
slope does not exceed 30 °, width of machine operation space> 8m, land level I-III, not
waterlogged.
 Use a bulldozer in the direction of cutting the slope to dig up the slope to lower the natural level to
the height that allows the pit to continue digging the ceiling, or use the wall against the wooden
boards, if the excavation volume is low, excavate manually because it can not gather the machine
into this position.
 Excavated earth to create construction site, waste from the foundation pit can be transported by
container and crane.
§ ­ êng­mÆt­®Êt­tù­nhiªn

Fill up the
foundation pit
MÆt­b»ng­®µo­b»ng­m¸y­ñi

Organize spread
footing
construction

Hè­mãng­®µo­b»ng­thñ­c«ng


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CONSTRUCT FOUNDATION PIT BY BARE EXCAVATION METHOD
Construction
methods for
foundation pit

 Excavate by inverse bucket excavator :
 Scope of application: Land level I-III, for the terrain is relatively flat, or combination of surface
leveling and making the road for digging machines with land transporters to the construction site.
 These points should be considered when designing organizations using excavators  :

Bottom foundation
treatment

Concreting spread
footing

Fill up the
foundation pit

Organize spread
footing
construction

 Range of machines: the ability to reach out, pour high, dig to the lowest position.
 The position of the machine compared to the edge of the foundation pit to ensure the stability of the
talus.
 Digging bucket capacity and productivity of the machine.
 Movement of the machine so that it can dig all the positions of the foundation.
 Number of soil trucks and transportation arrangements.


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CONSTRUCT FOUNDATION PIT WITH STRUCTURE AGAINST THE WALL
Construction
methods for
foundation pit

Bottom foundation
treatment

Concreting spread
footing

Fill up the
foundation pit

Organize spread
footing
construction


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CONSTRUCT FOUNDATION PIT IN THE SUBMERGED CONDITION
Construction
methods for
foundation pit

 Excavate foundation pit with submerged base rocks:
 If the flow is narrow, shallow water: use dams.
 If the rock surface is exposed on natural ground: use a siege of soil

Bottom foundation
treatment

Concreting spread
footing

Fill up the
foundation pit

Organize spread
footing

construction

 If the flow is wide, flooded deeply :
use barrels


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CONSTRUCT FOUNDATION PIT IN THE SUBMERGED CONDITION
Construction
methods for
foundation pit

Bottom fundation
treatment

Concreting spread
footing

Fill up the
foundation pit

Organize spread
footing
construction

 Dry treatment of the excavated ground :
 When the groundwater level is higher than the bottom of the foundation, it must be dried before

excavation
 Often used small wells. The suction head is a 60-80cm diameter filter tube, 1.7m long, deep in the
floor with erosion control, suction cups connected to the 38-55mm diameter suction pipe, 5-7m long
connected to the concentrated water pipes 75-125mm diameter.


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BOTTOM FOUNDATION TREATMENT
Construction
methods for
foundation pit

Bottom foundation
treatment

 Treating the bottom of the foundation is soil ground:
 Requirements: 0.5m bottom of the foundation must be excavated by hand to ensure the original,
only take the land, not compensated. Handcrafted thin layer 10 ÷ 15cm.
 Finished excavation should be poured concrete footings. If you have to wait for a new concrete
pouring time, leave 0.1­÷ 0.2m just before the concrete pouring and nodularize the floor with the
foundation.
 The role of padding layer:

Concreting spread
footing

Fill up the

foundation pit

Organize
spreadfooting
construction

 Protects the ground below the bottom of the foundation from being damaged by travel and
trampling during the preparation of the foundation pouring.
 Smooth the bottom of the foundation, forming a lining for cleaning reinforcement and water
loss of cement. It ensures the quality of concrete footings.
 Composition of the foundation: The lining foundation is lower than the bottom of foundation. There
are 2 types  :
 Crushed sand mixture with a thickness of 15cm compacted if encountered wet clay
background. Before pouring the cushioning layer, it is necessary to remove the pasty soil
layer at the top then spread out and leveling gradually.
 Mortar low grade concrete 10cm thick. This is a very effective method because it is clean,
stable should be the bottom plank for pedestals. If the platform is reinforced, the foundation
must be used. Concrete foundation lining directly into the ground just digging and leveling
and flapping by hand. If the background is permeable, use dry concrete mixture to spread and
compact, the concrete will soak and seal.


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BOTTOM FOUNDATION TREATMENT
Construction
methods for
foundation pit

 Treating the bottom of the foundation is rock ground:
 Have to dig up the layer of low intensity on the top above the average 0.5m and make the surface
flat.


Bottom foundation
treatment

Concreting spread
footing

Fill up the
foundation pit

Removing layers of weathered stone with pressure hammer, if small volume can apply small and
shielded explosive measures. Waste rock is put into containers and crane.

 After that, burying the anchor against the sliding of the stone: normal hole drilling Φ­42, l = 50cm
according to the sieve diagram, distance a = 50cm.
 Thoroughly clean the borehole with water, ratio 1 : 2 cement mortar filled with boreholes, without
air bubbles in the hole.
 Anchor the Φ­32 bars with 100cm long edges closed into the hole was stuffed mortar close to the
bottom.
 Then, use a 5 cm thick concrete slab all over the bottom of the foundation to create a flat level
design of the bottom of the foundation.

Neo­chèng­tr­ î t

Organize spread

footing
construction


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WATER PUMP IN FOUNDATION PIT
Construction
methods for
foundation pit

Bottom foundation
treatment

Concreting spread
footing

Fill up the
foundation pit

Organize spread
footing
construction

 Requirements:
 The water pump does not allow the bottom soil to soak in water and during the pouring of concrete
and when the foundation is fixing not to flood the bottom of the foundation. Therefore, it is
necessary to regularly pump the water level lower than the bottom of the foundation until the

concrete foundation finishes setting (after 4 hours).
 Around the bottom of the foundation build ditches to drain, slope along 0.6% leading to one or two
pits located at the corner of the hole, the hole is more deep bottom foundation 0.7m. The
capacitance of the capacitor must be 1 hour to hold the above types of discharge. The pump works
no less than 10 minutes. Around the pits, the wood was used to prevent landslides and gravels or
grit gravel pit bottom.

 Intrusive water sources :
 Underground water: Qng = 1,6.q.F
F : Infiltration area, m2; q : intensity permeable through 1m2 foundation bottom, m3/h.m2.
depending on the type of background, with fine sand  : 0,15÷ 0,25; medium sand : 0,3÷ 0,5; fine sand :1÷ 3.
 Rain water: Qmưa =

m.F .h
24

m : reserve factor = 1,5; F : area of the bottom pit m2; h : daily rainfall of the basin.
 Condensate water : already in the pit because of the pump to clean the bottom foundation : Qtụ.


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CONCRETING SPREAD FOOTING
Construction
methods for
foundation pit

 Requirements:

 The foundation is not reinforced, if any, only the bottom to
strengthen
 It is necessary to erect steel reinforcement at the pier and
abutment body before pouring the footings.

Bottom foundation
treatment

 Concrete in each floor of the foundation is poured
continuously in a batch, if large volume is divided into two
main flows are horizontal, each block <50m2, when the block
is large, can be divided into both horizontal and vertical

Concreting spread
footing

Fill up the
foundation pit

Organize spread
footing
construction







Grout supply

Pour and compact the concrete
Surface treatment
Concrete maintenace
Time for form removal: When the concrete foundation reaches 2.5 MPa


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FILL UP THE SPEAD FOOTING
Construction
methods for
foundation pit

Bottom foundation
treatment

Concreting spread
footing

Fill up the
foundation pit

Organize spread
footing
construction

 Requirements:
 After the foundation is 1 meter away from the NG and tested and covered with soil.

 Prior to filling the soil to scan the hot waterproof plastic..
 The embankment must meet the technical requirements and embellished by the design, covering all
four corner holes of 0.2 m each layer and thoroughly compaction by hand.
 Pay attention to the landfill and the removal of all types of planks and trees.


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ORGANIZE SPREAD FOOTING CONSTRUCTION
Construction
methods for
foundation pit

 Content:
 Planning the construction site, arranging machinery, equipment and personnel, preparing material
and supplying energy to carry out the construction work continuously.
 It should be consistent and reasonable between stages.

Bottom foundation
treatment

Concreting spread
footing

Fill up the
foundation pit

Organize spread

footing
construction