Application of Engineering Survey Technology in Building Construction
Engineering surveying technology refers to the general term of various surveying theories, methods and technologies used in the survey and design, construction and management stages of engineering construction. The service fields of traditional engineering survey technology include construction, water conservancy, transportation, mining and other departments, and its basic contents include mapping and lofting two parts.
Engineering surveying mainly includes engineering surveying for engineering buildings and industrial surveying for equipment and machine installation. In the subject can be divided into general engineering survey and precision engineering survey.
The main task of engineering surveying is to provide surveying and mapping guarantee for all kinds of engineering construction and meet the requirements of engineering.
Precision engineering surveying represents the development direction of engineering surveying. The construction of large special precision engineering is the driving force to promote the development of engineering surveying.
According to the different functions of survey in each stage of construction engineering, construction engineering survey can also be divided into three aspects: pre-construction survey, in-construction survey and post-construction monitoring:
The survey work is mainly to provide large scale topographic maps for engineering construction, and to complete the survey work in the planning and design stage of architectural engineering by means of ground manual mapping and photogrammetry mapping.
Ground manual mapping is based on the principle of overall to local construction projects, to establish plane and elevation control points in the survey area, according to the control points mapping topography and geomorphology. The survey work before construction is the foundation of a project, must be careful, can not have the slightest bit careless.
Measurement work is mainly in accordance with the design and construction requirements to establish the construction control network, and on this basis in the field to the required precision lofting out of the building and production equipment position work, is the foundation of construction and installation of construction engineering, construction has important guiding significance.
In recent years, due to the construction process of measurement and lofting work quality problems caused by the bad end of the building, the main reason is due to the quality problems of measurement and lofting work, measurement management and quality control is not in place.
The measurement work is to monitor the status of engineering buildings and ensure their safe operation of deformation observation.
Its main focus is to carry out vertical displacement (settlement), horizontal displacement, tilt, deflection, wind vibration, sunshine deformation and other content observation. It is to ensure the quality of construction engineering can meet the requirements of the use of measurement work. It is also an important work to protect the personal safety of building users.
Application of surveying technology in engineering buildings
The control measurement is the foundation of construction, the control measurement of the building is generally arranged in the form of grid, in order to facilitate the construction, the coordinate system uses the building coordinate system, the coordinate axis is parallel to the main axis of the building. The layout of the engineering control network generally follows the principle of from the whole to the local, hierarchical distribution network and step by step control.
Before the construction of the project, firstly, the building on the construction drawings should be lofted and positioned in the field and the control elevation should be measured, so as to provide the benchmark for the next construction. In the stage of foundation construction, the construction of foundation pile position needs more accurate engineering survey technology.
In the process of earthwork excavation and foundation construction of floor, due to the design requirements, earthwork excavation of floor, cap and bottom beam is to avoid the soil layer below the flexible working face as far as possible, so careful and careful measurement work can control the depth and part of earthwork excavation, avoid overdigging and disorderly digging.
Engineering measurement in the foundation construction stage is another key point is the positioning of the foundation wall column reinforcement line, for the structure of complex, large area of the project, only careful and meticulous measurement of the line can ensure the quality of wall column inserted reinforcement, to avoid deviation, displacement and other circumstances.
Lofting the design drawings of the plane position and elevation of engineering buildings, with certain measuring instruments and methods to measure the set to the field of measurement work called construction lofting (also known as construction line).
Construction lofting is on the contrary, according to the design size of the building, find out the geometric relationship between the position of each part of the building feature points and control points, calculate the distance, angle, elevation, coordinates and other lofting data, and then use the control points, on the ground to determine the building feature points, according to the construction.
Read the design drawing, calibrate the control point data of the building contour and mark the dimensions, record the drawing review result.
Select the method of measuring lofting and calculate the lofting data or write the procedure of measuring lofting calculation, draw the lofting sketch and independently check and prepare the instruments and tools, the instruments used must be within the valid verification period.
2. Polar coordinate method
- Set up the total station on the control point and straighten the center.
- After initialization, check the instrument settings: temperature, pressure, prism constant;
- Input the three-dimensional coordinates of the measurement site, measure and input the height of the instrument;
- Input the coordinates of the rear view point, and look at the rear view point;
- Aim at another control point and check the azimuth or coordinates;
- The eye line height of the instrument is checked with a prism or ruler at another known elevation point;
The person in charge of measuring and lofting will compare the labeled data with the recorded results one by one, and check the geometric dimension relationship between the points and the relative dimension relationship with the edges of the relevant structure and record it, so as to verify the correctness of the labeled data and the lofting points. Fill in the measurement lofting and submit the sample sheet.
3. Error processing
Construction lofting results are usually immediately (or a few hours later) delivered, often can not wait to check the correctness of the results.
This requires lofting operators to have self-check conditions everywhere in the operation, in order to find mistakes in time, timely correction. Try to avoid errors.
4. Retest work
Survey retest (inspection and survey) is an essential work to ensure the quality of construction projects.
The purpose of retest is to check whether the plane position and elevation data of the building (structure) meet the design requirements. In the past, most of the construction survey accidents were caused by neglecting the retest work. External measurement records should be fully reviewed by another surveyor.
Building elevation measurement
Elevation is the basis of vertical positioning of buildings. Elevation is often measured using a level.
For any point to be measured, it is necessary to find a known point to measure.
For the case that the distance between the two points is close, the level should be set up in the middle of the two points, and the tower should be set up at the known point for reading record a1, and then the tower should be set up at the point to be measured for reading record b1.
Assuming that the elevation of the known point is X, then the elevation of the point to be measured is Y=X+a1-b1. If it's far away, you can't measure it all at once, so this is a station, Y=X+a1-b1 and that's just the elevation of the turn point.
Same procedure, same algorithm, until the tower is not the turn point, but the point to be measured, the job is done.
Measurement of verticality
Perpendicularity measurement is an important part of construction engineering measurement. Perpendicularity measurement refers to the vertical projection from up to down or a vertical line provided by the instrument on a station, and the coordinates on the plane are calibrated in the required position after vertical transmission to ensure the perpendicularity of the building.
To sum up, the construction survey is firstly based on the general plan of the project and the topographic conditions to establish the construction control network, and then the site leveling, according to the construction control points in the field to determine the main axis and auxiliary axis of each building, and then according to the main axis and auxiliary axis of the calibration of each detail of the building. After the completion of the project, it is necessary to carry out completion measurement, and regular deformation observation during and after the construction.
The common survey tool in building construction includes total stations and GNSS receivers, learn more about the tools,
Total Station: https://www.singularxyz.com/TS1000.html
GNSS Receiver: https://www.singularxyz.com/Y1.html