INDIA
GBT Site Survey & Construction Procedure.
Now, we will discuss about GBT Site Survey & Construction Procedure
Survey ToolsSurvey tools are same for RTT & GBT sites;
White Paper, Scale (30cm), Pencil, etc,. to draw the rough layout Measuring tape – Steel tape or Cloth tape
Compass
Tower Details like
Height
Weight
Base Width
No of Legs (3 legged tower OR 4 legged tower)
Shelter Details like External dimensions, No of pedestals, c/c distance of pedestals, Shelter Weight
DG Bed Size, DG Weight
Earth pit size, No. of pits & c/c distances (INDIA)
Now, we will discuss about GBT Site Survey & Construction Procedure
Survey ToolsSurvey tools are same for RTT & GBT sites;
White Paper, Scale (30cm), Pencil, etc,. to draw the rough layout Measuring tape – Steel tape or Cloth tape
Compass
Tower Details like
Height
Weight
Base Width
No of Legs (3 legged tower OR 4 legged tower)
Shelter Details like External dimensions, No of pedestals, c/c distance of pedestals, Shelter Weight
DG Bed Size, DG Weight
Earth pit size, No. of pits & c/c distances (INDIA)
SITE SURVEY – GBT
SURVEY PROCEDURE / CHECKS
(INDIA)
SITE SURVEY – GBT
Before going to the survey, we should know the following dimensions:
Tower Base Width & Excavation Width,
Shelter Size
DG Size
With the above details we can find out whether the given size of the site is suitable or not to arrange the all above equipments.
(INDIA)
SITE SURVEY – GBT
Tower Excavation Width
If foundation drawing is available, excavation width can be know from that drawing
If foundation drawing is NOT available: take excavation width = 2 x Tower Base width
40 m
Tower
3.2
6.4 = 2 x 3.2
This is only for survey purpose; during execution we have to follow as per foundation drawing only.
Excavation Line
4.01.2 3.53.3
ELECTROTEK(INDIA)ELECTROTEK(INDIA)
1. Write Site Name, Tower Ht., Site Address at the top of the page.
Kota – 40m, Near Petrol Pump, Main Road, Nellore Dt.
3. Indicate the NORTH direction.
2. Draw the boundary line with dimensions.
15m
20m
N
4. Mark the adjacent roads, surrounding structures and its distances.
Street road
Green
Field
Green
Field
5. Mark the site level w.r.t. the road level
6. Mark the proposed area of tower, DG & Shelter
12. Write your name, Employee ID No., Date & Sign
P Rajesh
401501
03.03.06
Rajesh
P
9. Mark the proposed Earth Pits
11. Mark the nearest Elec. Pole / Transformer to the site
PREPARATION OF LAYOUT AT SITE
PROCEDURE / CHECKS
13. Take the Owner sign and customer site engineer sign
Electric Pole
Make sure that, 0o Should be placed upward of your
page
14. This Rough layout should be sent to Design department to prepare CAD Layout
Main Road
15m
20m
40 m
Tower
3.21.51.5
Shelter
2.5x3.2
DG
2 x 1.5
1.5
2.5
1.5
1.5
Security
Room
3 x 3
+ 0.5 m w.r.t. the road level
EP
0.5 x 0.5
EP
0.5 x 0.5
EP
0.5 x 0.5
EP
0.5 x 0.57. Mark all dimensions w.r.t. the boundary as shown
8. Mark the cable tray rooting
10. Mark the Security room and gate GATE
Owner Customer
4.01.2 3.53.3To design the foundation, we require soil parameters like SBC, Density, Angle of repose etc.,
Kota – 40m, Near Petrol Pump, Main Road, Nellore Dt.
15m
20m
NStreet road
Green
Field
Green
Field
P Rajesh
401501
03.03.06
Rajesh
P
SOIL TEST
Electric Pole
Main Road
15m
20m
1.51.5
Shelter
2.5x3.2
DG
2 x 1.5
1.5
2.5
1.5
1.5
Security
Room
3 x 3
+ 0.5 m w.r.t. the road level
GATE
Owner Customer
Soil sample to be collected within the proposed area of the tower
Soil sample collected areas
Soil report should be sent to design department to design the foundation
The following are the different types of foundations depends upon the soil conditions
Isolated Foundation
Raft Foundation
Pile Foundation
Rock-Anchor Foundation
ELECTROTEK(INDIA)
CONSTRUCTION PROCEDURE (Raft Foundation)
Site Cleaning
Marking
Excavation
Levelling of excavated pit
Laying of PCC
Bar-bending
Shuttering
Raft Concreting
1st lift column concreting
Tie beam concreting
Template Fixing
Final concreting
Backfilling with proper compaction
INDIA)
4.01.2 3.53.3Carry the CAD layout and foundation drawing
NStreet road
Green
Field
Green
Field
Marking
Main Road
1.51.5
+ 0.5 m w.r.t. the road level
At site
Mark the distances from the boundary Mark the Excavation line with the help of Foundation Drawing
Ex.: 6 m is the width of the excavation
6
6
Check the diagonal distances
= 8.485 m62 + 62
Excavation with JCB is recommended
Excavation
In case of lose soil, proper shoring should be provided to prevent soil collapse.
ELECTROTEK(INDIA)
Supports to prevent the soil collapse In case of seepage, de-watering
should be done
Seepage of water
Motor for de-watering
Excavation with JCB is recommended
Excavation
Proper levelling should be done to maintain uniform foundation depth
Levelling
Check the depth of foundation at all corners as per drawing
In case of lose soil, proper shoring should be provided to prevent soil collapse.
In case of seepage, de-watering should be done
PCC (Plain Cement Concrete)
Grade of Concrete
Proportion
Ballast (cum)
Sand (cum)
Cement (cum)
M10
1:3:6 0.9 0.45 0.15 4.5 bags
1:4:8 0.92 0.46 0.115 3.45 bags
1:5:10 0.95 0.475 0.095 2.85 bags
Volumes per Cu M
Generally used mix
PCC – Thickness should be as per drawing
Bar bending – Shuttering – Concreting
PCC
After laying the PCC, mark the column positions to place the column reinforcement.
Check the c/c distances and diagonal distances
Bar bending – Shuttering – Concreting Bottom reinforcement in two way direction
Cover Blocks b/w the PCC and bottom reinf.
Bar bending – Shuttering – Concreting Column reinf.
Place the column reif. exactly on marked portion of PCC
Side view
Bar bending – Shuttering – Concreting
Place the column reif. exactly on marked portion of PCC
Side view
Tie the ‘L’ bends of the column reinf. to the bottom steel
Bar bending – Shuttering – Concreting
Column Stirrups
Set
Stirrups at the top of the column reifn.
Stirrups at the bottom of the column reifn.
First arrange the stirrups at top and bottom of the column reinf.
Bar bending – Shuttering – Concreting
Arrangement of chairs to support the top reif.
Chairs
Bar bending – Shuttering – Concreting
Stirrups
Top reinf. of the raft
Bar bending – Shuttering – Concreting
If chairs are not provided properly at regular intervals, top rainf. may sag as shown
Raft Shuttering
Bar bending – Shuttering – Concreting
Now it is ready for Raft Concreting
Bar bending – Shuttering – Concreting
Checks before Raft Concreting
Check the size of the raft reinf. and spacing as per drawing or not
Check the size of the column reinf. and no. of bars as per drawing or not
Check the c/c dist. and diagonal dist. of column reinf. As per drawing or not
Check the raft width and depth as per drawing or not
Check for shuttering gaps
Mixing of concrete should be machine mix
Grade of concrete should be M20 (as per drawing) as discussed in RTT
While concreting, vibrators should be used for compacting the concrete
Bar bending – Shuttering – Concreting
Aggregate should be immersed in the concrete as shown to develop the bond for column concrete
Picture at siteAfter Raft Concrete
Bar bending – Shuttering – Concreting
Side shuttering can be removed after 24hr. from the concreting
Arrange the column shuttering for first lift concreting
Curing should be done properly for the minimum period of 7 days
Bar bending – Shuttering – Concreting
Before first lift concreting:
Again check the c/c distance and diagonal distance of the column shuttering
Check the column sizes as per the drawing or not
Aggregate should be immersed in the concrete as shown to develop the bond for 2nd lift column concrete
Shuttering can be removed 12hr. after concreting
Bar bending – Shuttering – Concreting
After Concreting
Bar bending – Shuttering – Concreting
Tie beam & 2nd lift column
2nd lift column shuttering
Tie beam shuttering
Bar bending – Shuttering – Concreting
Tie beam reinforcement
Tie Beam C.S.
Position of T B Bars
Bar Bending
Bar bending – Shuttering – Concreting
Arrange the tie beam reinf. Tie beam reinf.
Check the alignment of the columns by pulling the thread from one end to other
All corners should be in a straight line
Bar bending – Shuttering – Concreting
Template fixing
Recall the procedure which we have discussed in RTT site
Template & Foundation bolts fixing
Measures before fixing the template on foundation
Fix the template on ground
Check the c/c distance at all sides as per drawing
(In this example c/c distance is 2.1 m )
Check the diagonal distance in both ways
Bar bending – Shuttering – Concreting
Template fixing
Procedure for water level checking
Alignment & Fixing of Anchor Bolts
Isometric View
Side View
Top View
Bar bending – Shuttering – Concreting
Template fixing
Procedure for water level checking
Bar bending – Shuttering – Concreting
Template fixing
Procedure for water level checking
In the same way check at all corners as shown
Bar bending – Shuttering – Concreting
Template fixing
Top level should be same for all fn. bolts
Bar bending – Shuttering – Concreting
Now it is ready for final concreting
Checks before Final Concreting
Check all dimensions are per drawing or not. i.e. Tie beam size, column size and tie beam distance from the top of the column etc.,
Check the tie beam reinf. Size and no. of bar at top and bottom as per drawing or not
Tie Beam C.S.
Check all foundation bolt thread portion is covered to protect while concreting
All the threaded portion of the fn. Bolts should be applied by Greece and covered with polythene cover
Bar bending – Shuttering – Concreting
Now it is ready for final concreting
After Concreting
Bar bending – Shuttering – Concreting
Site shuttering can be removed after 24hr. (except tie beam bottom shuttering)
Tie beam bottom shuttering can be removed after 5 to 7 days
Template can be removed after 12 hr. from the concreting period
Curing should be done min. of 14 days
Back filling
Back filling should be done with proper compaction up to the above ground level to allow settlement in future
Excavation in Hard Rock
If we found hard rock for small depth, it has to be removed to reach the complete foundation depth
Excavation in Hard Rock
If we found hard rock for small depth, it has to be removed to reach the complete foundation depth
If we found hard rock nearer to the below ground level, we have to go for the Anchor Foundation
Level the rock surface
Drilling
Anchorage
Anchoring Rod
Chemical Grouting
Excavation in Hard Rock
If we found hard rock for small depth, it has to be removed to reach the complete foundation depth
If we found hard rock nearer to the below ground level, we have to go for the Anchor Foundation
Level the rock surface
Drilling
Anchorage
Raft and Columns
Pile Foundation
If the bearing capacity is low in the given area, piles are required
Boring
Pile Foundation
If the bearing capacity is low in the given area, piles are required
Boring
Reinforcement & Piling
Pile Concreting should be of M25 mix (1:1:2)
Pile Cap & Column
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