First, the technical focus of engineering surveying.
The control of the structural plane size and elevation of this project puts forward higher requirements for engineering surveying.
1. The site plane control network and the main axis of the building should be accurately positioned and measured according to the reviewed building red line pile or urban survey control point, and the pile position should be protected. The spacing of the stakes of the plane control network should not be greater than the length of the steel ruler used, and should form a closed figure, and its measurement allowable deviation should meet the requirements of the specification.
2. The outer outline axis of the building should be measured on the concrete floor cushion according to the site plane control network, and the detailed axis and relevant boundary lines should be released after the closure and calibration are qualified. The allowable deviation of the foundation pay-off size shall be in accordance with the provisions of Table 2.
Table 1 Allowable deviation of basic pay-off size
Note: The allowable deviation of the angle between the outer profile axis should be 1.
3. After the pay-off acceptance of the first layer, the control axis should be measured on the outer surface of the structure, and used as the benchmark for the vertical projection of the main axis of each construction layer. The vertical projection of the axis should be measured vertically from the starting elevation line of the first floor with the building axis control pile as the measuring station, and each building should be transmitted upwards from three places. When the elevation difference of the three points is less than 3mm, the average value should be takenOtherwise, the test should be re-inscribed. The allowable deviation of the vertical projection should be in accordance with the provisions of Table 2.
Table 2 Allowable deviation of vertical projection of the axis.
4. After the control axis is projected to the construction layer, a closed figure should be formed, and its spacing should not be greater than the length of the steel ruler used. The control axis should include:
l The outer profile axis of the building;
l Axis on both sides of deformation joint and settlement joint;
l Axes on both sides of the stairwell;
l The demarcation axis of the unit and the construction flow section.
When the construction layer is laid out, the axis should be checked and measured on the structural plane, and then the detailed axis and the edge lines such as walls, columns, beams, doors and windows should be measured, and the allowable deviation of the pay-off should be in accordance with the provisions of Table 4.
Table 3 Allowable deviation of pay-off of construction layer.
5. The site elevation control network should be guided according to the level point or known elevation point after review, and the elevation should be measured by the conjunctive measurement method, and its closure difference should not exceed 6mm (n is the number of stations) or 20mm (l is the length of the survey line, in km).
6. Before the building envelope is closed, the control axis should be guided to the inside of the structure as the basis for interior decoration and equipment installation and pay-off.
7. In the field plane control measurement, it is advisable to use a total station or rangefinder with a ranging accuracy of not less than (3mm 2 l0-6 d) and an angle measurement accuracy of not less than soil level 5 (d is the ranging, in mm).
In the site elevation measurement, it is advisable to use an automatic leveling level with an accuracy of not less than S3.
In the vertical projection of the axis, it is advisable to use a 2-stage laser theodolite or a laser automatic lead straightener.
Second, the supervision countermeasures of engineering surveying.
1. Before the construction of the project, the supervision party shall require the contractor to prepare a "special construction plan for engineering surveying" for the characteristics of the project to ensure the smooth progress of the engineering surveying workThe supervision party will organize the relevant supervision engineers and even relevant survey experts to review the "special construction plan for engineering surveying" submitted by the contractor, and the focus of the audit should be on the scientificity, rationality and operability of the construction plan.
2. Before carrying out engineering surveying, the supervising party shall check whether the measuring instruments and tools of the contractor are within the validity period of the verification, and whether the verification unit has the corresponding qualification levelAt the same time, ensure that the instruments and tools used by the supervision party for review are also within the validity period of the verification;And carry out the comparison of the measuring tools of both sides to ensure the accuracy of the measuring tools. In addition, the supervising party should also check whether the contractor's surveyors have been professionally trained in surveying to ensure that the surveyors can correctly use the measuring instruments and tools, and the measured results can meet the requirements of the specification.
3. The supervising party will review the intermediate measurement calculation results submitted by the contractorThe company's high-precision measuring instruments are used to review the contractor's measurement results on site to ensure the reliability and accuracy of the measurement data.
4. There should be higher requirements for the selection and layout of the plane control network of the building, or for the setting and management of the stakes of the control points, so as to ensure the stability of these control networks and points in the process of structural construction, so as to ensure that the requirements of structural construction accuracy are met.
5. For the construction measurement of curves and surfaces, it is necessary to carry out mathematical calculations according to the law of change of curves or surfaces (such as the mathematical equations of the trajectory of points or lines, etc.), and the spacing of the measuring points should be able to ensure the requirements of construction.
6. During the construction, the settlement of the building should be observed regularly as required, and if the settlement of the building is found to be abnormal, the construction should be stopped immediately, and the reasons for the abnormal settlement should be analyzed, and the corresponding measures should be taken before the construction can be continued, so as to ensure that the final settlement of the building is within the specification.
7. The building must meet the allowable deviation of the cast-in-place concrete structure.
Table of allowable deviations of cast-in-place concrete structures.
3. Supervision of completion survey.
The completion survey is not only the basic basis for accepting and evaluating whether the project is constructed according to the design, but also the basis for management, maintenance, reconstruction and expansion after the project is delivered. Therefore, the company attaches great importance to the completion survey, and will strictly supervise the construction unit to do this work seriously and realistically. The content includes the following:
Master plan. It includes buildings, structures, etc.
Diagram of the upper and lower sewer pipes.
Power piping diagram.
Power & Communication Diagrams.
The key to doing a good job in the completion survey is to urge the construction unit to accumulate various acceptance data in an orderly and non-obstructive manner from the beginning of the supervision work, especially the concealed engineering data.