02-GUIDELINES FOR MARKING
GUIDELINES FOR MARKING OF A STRUCTURE
The followings are the important steps that are to be followed for Marking a Structure as per the approved drawings
1. The location of the structure shall be identified with L.S. sheets together with a contour site plan indicating TBL/FSL/CBL & ground levels as indicated in the approved drawing.
2. After careful study of foundation drawing, it has to be divided into different drawings at different elevations such as (i) drawing for foundation excavation (ii) drawings for P.C.C laying (iii) drawing for footing or cut off, whatever be the case and marking on the ground has to be given according to it in each case.
3. A Benchmark has to be established at the vicinity of the site carrying it from an available nearby G.T.S Benchmark by double-checking levels.
4. (a) Suitability of the foundations may be verified to the designed stresses by conducting various field tests such as plate load test before proceeding to the foundation concreting.
(b) Borehole data / T.Ps up to hard strata or for minimum 2 meters for shallow foundation / up to 1/3rd embankments depth below maximum scour depth along the centre line at suitable intervals depending upon the importance of the structure with minimum 3 meters of Trial Pit covering both drain and canal at the centre, upstream and downstream sides shall be collected and got tested to ascertain the bearing capacity of soil as per approved drawings.
5. (a) Centre line of the structure in both the (Perpendicular) directions shall be fixed on concrete pillars and the distances of each component of foundations shall be verified with respect to the centre line, at each stage of foundation concreting.
(b) The length of the structure in the diagonal direction also to be verified.
6. The centre line of a structure shall be established by a theodolite or total station and GPS Software etc.
7. Centreline pegs and TBMs and chainage pegs shall be established prior to marking of any structure.
8. Drainage outlets and diversion roads arrangements shall be considered while giving marking to the structure.
9. Silt traps must be arranged and silty water let down into natural drain below.