What Is Importance And Requirement Of Survey In The Construction | Checklist Of Site Engineer

 

IMPORTANCE AND REQUIREMENT OF SURVEY | CHECKLIST OF SITE ENGINEER

The survey plays an important role in construction activities. The basic requirement is to ensure proper location and alignment, including the height slope required for the structure or overall layout of a plant. The survey is conducted to maintain the above requirement. The following is a summary of the survey terms used:

SURVEYING: Surveying is the art of making such measurements as will determine the relative positions of points on the surface of the earth or on structure in order that the shape and extent of any portions of the earth/structure may be ascertained and shown on the map or plan.

 

LEVELING: Levelling is the art of determining and representing the relative heights or elevations of different points on the surface of the earth/structure.

 

SEQUENCE TO BE FOLLOWED FOR THE SURVEY W.R.T. START OF THE WORK:

Following are the salient points/ sequence of the survey to be followed for start of the project activates/ pour: -

WORK IS DIVIDED IN TWO PARTS.

A. To start a new project: Establishing of Main grid lines and Benchmark with reference to known datum/reference to start in new work.

B. For a pour in existing structure: Use of existing reference/benchmark in the existing structure to define the location, alignment and elevation of a pour.

 

USE OF SURVEY IN VARIOUS DAY-TO-DAY ACTIVITIES OF CONSTRUCTION.

·  Before we deal with the uses of survey for various activities, the following steps are necessary to carry out.

·    Transfer of reference line at each Building/floor to carry out checking of various activities.

·      Transferring of BenchMark at each Building/floor.

·  Above two activities should be performed with great care and without any error, as the effectiveness of total checking depends on these reference points.

·       Establishing layout of the building.

·       Establishing benchmark to check elevations of different floor etc.

·       Use for checking of formworks:

a)   Alignment checking

b)  Checking of verticality.

·       Tolerance for formwork

a)   Section dimension - ± 5 mm

b)  Plumb/ verticality - 5mm in 5 mtr. But should not cumulative.

·       Use in checking of critical EPs.

a)   Checking of location

b)  Checking of elevation tolerance

c)   Before concreting ± 2 mm.

d)  After concreting ± 6mm.

e)  Tolerance on angle ± 0.500.

 

Survey is very important at

·       Pre – construction stage

·       During construction stage

·       Post-construction stage

 

Site Engineers must be aware regarding requirement and importance of survey at pre-construction, during construction and post-construction stages. Few of the requirements are detailed below:

 

PRE-CONSTRUCTION SURVEY IS REQUIRED FOR THE FOLLOWING:

1.   Defining the plant area in 20m X 20m plant grid pattern with existing permanent reference.

2.   Location of various plant structures within defined grid established as above.

3.   Making specific benchmark to take up the work within building/structure.

4.   Marking and identification of a part of the structure in various pours at various elevation w.r.t defined Benchmark / reference.

5.   These marking are possible by:

·       Theodolite.

·       Measuring tapes.

·       Dumpy level.

·       Total station.

6.   At the start of construction- usually the reference point is marked on reference pillars 2-3 meters away from the edge of structure.

7.   After construction, it is transferred to permanent structure and subsequently all reference to be taken from common reference to avoid any cumulative error.

 

DURING CONSTRUCTION IS REQUIRED FOR THE FOLLOWING:

1.   During construction, the survey is very important. Following are the areas where a survey during construction requires by supervisor/site engineers.

2.   Maintaining alignment of wall and position of embedded part, pipe support/ piping sleeves etc.

3.   Maintaining the location of EP’s / specifically critical EP’s.

4.   Maintaining the concrete top elevation of plate EP’s / Critical EP’s.

5.   Maintaining the concrete top elevation during finishing of green cutting.

6.   Maintaining the slopes of floors.

7.   Maintaining the levels of sumps.

8.   During concreting survey is made to ensure the location of PVC water stop.

 

POST CONCRETE SURVEY IS REQUIRED FOR THE FOLLOWING:

1. Post the concrete survey is done for all critical pours to ensure the final position of EP’s / Levels of concrete.

2. It is required to done to assess the tolerance in alignment/level/pockets/bolts etc. in the concrete structure.

3. Post concrete survey is done to examine the spot of honeycombed portion / visual observation of bulging and type of surface finish in concrete.

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