Before get downing a building work it is really of import to cognize about the land country on which the building work is to be carried out. To cognize the physical visual aspect of a land country surveying is done.In puting out, there are several methods.
But they had selected Grid Line method.Before structural hemorrhoids were started all grid lines were made by twine and heap places besides were marked by nogs. When beams and heap caps are excavated out line of those are needed. First grid lines, which are extended from one time casted portion of floor by theodalight, are made by strings ( When we start our developing portion of cellar floor had been finished ) .
From grid lines centre line of beams are marked and out line of beams and heap caps are besides made.Once floor is casted grid lines, column lineations, lift wall lineations, retaining wall lineations and step instance lineations are marked. On floors grid lines can’t be marked which is hard to tag and utilize because of columns are on the grid lines. So that alternatively of grid line 1000mm off line of grid line is marked.
From the chief two perpendicular grid lines, which are transferred from lower floor, other grids off lines are marked. When we mark grids off lines we use both manual and theodalight. Following grid off line distance is manually measured by long tape ( length of which is 50m ) and marked by pencil on grid line which is crossed by taging grid.On the cross tripods of theodalight is laid and centered on the cross.
When attempt port is laid home base is leveled to oculus degree. Then theodalight is fitted to the attempt port. First by looking through optical plumb bob instrument is set up reasonably closely over the cross by traveling the instrument legs while one leg contacts the floor. Then instrument is leveled about by the tripods caputs.
And instrument is centered accurately by traveling the theodalight on the home base.Finally instrument is accurately leveled by all three foot-screws. Before leveling all three foot-screws are brought to centre. The instrument is turned to be the bubble tubing on the upper home base is parallel to the line fall ining the two pes prison guards.
Then those two prison guards are turned to convey the air bubble to focus on. Like wise it is turned to be perpendicular to the line fall ining two prison guards and air bubble is centered utilizing merely 3rd foot-screw. The above process is repeated for the opposite way rotary motion and degree is checked.After puting the theodalight reading is set.
Therefore first lower clinch is tightened and upper home base is turned about to zero reading. Then upper clinch is tightened and it is turned to zero accurately by micro prison guard. Lower clinch is loosened and closely turned to the grid line marked. Lower clinch is clamed and focused on the grid line.
Micro prison guard is turned to accurately focus on the grid line and perpendicular line of cross-hair. Then upper clam is loosened and turned by 180 grade.It is checked whether it accurately coincide with grid line after concentrating the on grid line. It is turned by 90 grade and grid line alliance is marked by pencil on the floor.
Like wise it is turned by 180 grade and same process is followed. Line is marked by threading utilizing lasting marker ink. The above process is used for taging other grid off lines besides. From these grid lines columns out lines, lift walls out lines, retaining walls out lines and step instance out lines are manually marked.
While out lines are marked 200mm off lines are besides marked.Grid line transferring is the really of import thing in appraising. It should be done really carefully. Because if grid line is shifted by small all columns will be shifted so due to eccentricity of column construction may fall in.
First theodalight is set over the hole of the floor and optical plumb bob centre and down floor junction of two perpendicular grid lines are coincided. Theodalight is set as stated above.After puting the theodalight and reading, theodalight is focused on the mention marker of grid off line which is on the stiff frame, and lower clinch is clamped and theodalight is accurately centered over mention marker by micro prison guard. Then it is turned by 90 grade for look intoing with the mention.
Like wise other mention are checked. If mention marker is non available by plump British shilling, it can be checked. Therefore plump is hanged accurately over grid off line and checked. Two grids off lines in the perpendicular are marked and after taging is finished once more it is checked with the mention markers.
Grading is the portion of the surveying. It is besides of import in edifice building. There are two types of grading instruments which are Dumping degree and Engineer’s degree or Leaning degree.
- Dumping degree: – Telescope of this grading instrument is fixed to the upper home base stiffly.
And the telescope can be moved merely in horizontal plane. Once instrument is leveled without any other intermediate degree checking readings are taken. Here, while the instrument is flat upper home base and line of collimation are parallel. Of cause if degree is out by small due to quiver or some tolerance with the distance mistake of reading will increase.
Accurate is less.
- Engineer’s degree: -This is same as Dumping degree. In add-on this telescope is fixed to the upper home base as hing and tilting prison guard is attached to travel the telescope in perpendicular plane without altering the upper home base degree. Always it is easy to maintain the telescope horizontally.
Before every reading telescope is leveled merely by leaning prison guard without altering the upper home base, foremost of all upper home base is leveled. We can acquire readings with error independent of distance which mistake is really smaller than Dumping flat mistake. Engineer’s degree is more accurate than Dumping degree.
For the digging, we need height of digging which is measured by leveling instrument.
For the approximative measuring some other agencies can be used. But, for accurate measuring leveling instrument is used in our site, which is Dumping degree. For digging of beams, heap caps and lift Wellss degree is given by leveling instrument.Before reading is taken instrument should be leveled.
When we level, first tripod is set to be to the tallness of oculus degree and the home base is horizontal. Leveling instrument is fixed to the upper home base before repairing all three foot-screws are centered. Air bubble is centered closely by traveling the leg caputs without altering the place of legs. Then round bubble centered accurately by all three foot-screws.
Leveling of concrete: -When degree is given it is reduced by 5mm due to cutting mistake. While staff is kept on the concrete it may drop, to avoid staff is kept on Mason trowel.Leveling of slab formwork: – By inverter leveling method signifier work is leveled. While leveling staff is kept on GI pipe.
Because plyboard may debar it self but GI pipe is directly. First beam underside is leveled while it is leveled staff is straight kept on plyboard. Beam bottom plyboard can’t deflect because underside is fixed stiffly.Off line marker: – 1000 millimeter off line from the floor is marked on columns, retaining wall and lift wall.
For mention off line is marked on stiff frame. Off line taging on structural member is for easy to look into highs and for formwork devising.Plastering thickness marker: – we have already marked line of wall from that marked required thickness ( usually 16mm ) , utilizing of plump 2 nails nailed on wall and nylon twine tightened.