Measure the main construction methods and technical measures of the project

Mondo Social Updated on 2024-01-30

This section mainly expounds the engineering axis control, elevation measurement, settlement observation and other aspects. Due to the large number of professional subcontracts, the general contractor provides the control points for the construction control points of each specialty to ensure the unity of elevation and axis.

The project is located at the southwest corner of the intersection of Shengli Road and Yucai Street in Hengshui City. This project is an independent foundation, frame structure, and the site covers an area of 2780,000 square meters, with a total construction area of 25530,000 square meters.

1) General idea.

The whole engineering survey control is carried out in three stages, the earthwork excavation stage, the underground structure construction stage and the above-ground structure construction stage.

In the earthwork excavation stage, the reference point is mainly used, and RTK is used to control the edge line and elevation of the foundation pit earthwork excavation. After the earthwork excavation is completed, the GPS and total station are used to establish the first-level control network, and the corner net is used. In the construction stage of the structure, the steel ruler is used to control it with the total station and the lead straightener.

The layout of the plane control network adopts the principle of hierarchical layout and step-by-step control, which is divided into the first level network and the second level network (axis control network).

The secondary network (axis control network) is established on the basis of the first-level control network. The external control method is used for the measurement of the underground construction plane, and the axis control network is established on the periphery of the foundation pitThe internal control method is used for the measurement of the above-ground construction plane, the axis control network is projected on the first floor, the control point is transmitted synchronously with a laser vertical collimator, and the external control method is used for verification.

The detailed lofting work of the building is based on the axis control network, and the total station is used to carry out the polar coordinate method, and the steel ruler is used locally.

The level network is attached to the plane control network, and the observation is carried out according to the requirements of the third level, and it is used as construction control after adjustment.

2) Measurement basis.

Code for Engineering Surveying (GB50026-2007);

Current national and local norms and standards;

Drawings, design materials and related information documents provided by the owner, etc.

3) Measurement preparation.

The preparation of construction survey includes the review of drawings, the handover and verification of measurement and positioning base points, the organization of personnel and the selection, verification and verification of measuring instruments, and the preparation, demonstration and data preparation of measurement plans.

4) Main measuring instruments.

The main measuring instruments are shown in Table 61-1。

Table 61-1 List of Major Measuring Instruments.

5) Personnel organization.

The personnel organization is shown in Table 61-2。

Table 61-2 Measurement staffing and division of labor.

6) Retest of reference control points (nets).

Before the implementation of the surveying work, the reference control point (network) shall be handed over in writing and on-site with the owner, and the measurement results of the plane control point provided by the owner and the on-site control point (network) shall be retested, and if the retest result exceeds the limit, it shall be reported to the owner and the supervisor for review, and the surveying and mapping institute shall be required to retest.

7) Layout principle and accuracy.

Plane control is considered from the whole, following the principle of first the whole, then the part, hierarchical networking, and step-by-step control.

The layout of the axis control network is carried out according to the design general plan, on-site construction plan, etc.

The control point is selected in a place with good visibility conditions, safety and easy protection.

The accuracy specifications of the plane control network must conform to the table. Provisions of 1-4.

Table 61-3 Main technical indicators of wire measurement.

Table 61-4 Measurement accuracy requirements of plane control network.

The control pile position in the field must be protected with concrete, and a conspicuous fence railing is set above the ground to prevent the construction machinery and vehicles from colliding, see Figure 61-1。The first reference control point laid on the road adopts stainless steel marker, drills holes on the concrete pavement with an electric hammer, and fixes the stainless steel measurement mark firmly with planting glue.

8) Plane control network.

The plane control network is divided into three stages: earthwork excavation, underground structure construction and above-ground structure construction.

The excavation phase uses GPS RTK to control the edges and base elevations of the excavation with datum control points provided by the owner.

In the construction stage of the underground structure, the external control method is adopted, and the control points are laid on the road outside the building and the open space between the buildings. The total station is used to measure the control line of the building axis by using the polar coordinate method, and then the theodolite is used to cooperate with the steel ruler for detailed lofting.

The above-ground construction phase adopts the internal control method, and the construction to the structure 0At 00 hours, a steel plate is buried on the bottom plate of the building, and an axis control point is measured on the steel plate to establish a control network. Use the lead straightener to guide upwards layer by layer.

9) Establishment of elevation control network.

1) Embedding of control points.

The elevation control network is based on the level base point of the site provided by the owner, and is attached to the plane control network, and a total of 4 control points are laid out to form a level network.

2) Control the measurement.

The elevation control measurement is carried out according to the third-class level measurement requirements stipulated in the "Engineering Survey Code (GB50026-2007)", and the instrument is an S3 level level.

3) Accuracy level.

The elevation control network is rated as third-class, and the technical requirements are shown in Table 61-5。

Table 61-5 Technical requirements for leveling.

According to the datum control points provided by the owner, the GPS RTK is used for plane and elevation control. The RTK plane control accuracy is 10mm+1ppm, and the elevation control accuracy is 20mm+1ppm, which meets the accuracy requirements of earthwork excavation and pile foundation construction.

RTK has high control accuracy, fast measurement speed, simple and convenient operation, high measurement accuracy, and only one person is needed to complete the pay-off and measurement work. The collected data can be stored in the instrument and output directly to the computer, and the data to be lofted can also be directly transmitted to the GPS handbook and directly lofted on site. An RTK can control the excavation of several faces at the same time. When needed, it is also convenient to set up temporary control points in the pit, and use total stations and levels to control mechanical construction.

1) Calibration of axis control piles.

During the construction of the building foundation, the axis control pile is retested every half month to prevent the pile position from moving. The calibration instrument adopts the Leica TC802 total station with an angle measurement accuracy of 2 and a ranging accuracy of 2mm+2ppm.

2) Planar measurements.

1) Cushion axis lofting.

Before the foundation positioning and pay-off on the cushion, after the axis control pile is retested, the control line is projected by the theodolite with the positive inverted mirror straightening method, and the allowable error of the projection is 2mm, see figure.

The theodolite is erected on the axis control pile position of the foundation pit side, centered, leveled, and the axis sign in the same direction is viewed, and the required axis is projected to the plane layer of construction;There shall be no less than two longitudinal and transverse axes projected on the same layer;This is used as a check of angle and distance, see Figure 6 above1-4;After verification, other corresponding axes and details can be released on the plane.

3) Floor axis review.

After the completion of the measurement and pay-off of each layer plane or each construction section, self-inspection must be carried out, and the floor pay-off record form must be filled in time after the self-inspection is qualified and reported to the supervision and inspection line, so that the next process can be carried out in time.

3) Elevation measurement.

1) Elevation measurement: When the elevation is measured in the foundation pit, the elevation control network is first measured jointly to judge whether the leveling point in the field is touchedAfter the joint test is confirmed, the required elevation can be measured into the foundation pit. When entering the site for construction, the elevation control point is directly introduced into the foundation pit.

2) use 50m steel tape measure and level to the bottom of the foundation pit to measure the leveling point, guide not less than 3 points, and then use the level to check the three points in the pit, the mutual calibration shall not exceed 3mm, and take the average value as the control point of the construction elevation of the section, and guide to the nearby column for identification, so as to be used in construction. See Figure 6 for details1-5。

3) Elevation control line lofting.

After the formwork is removed, the level is used to copy the structure of each layer on the column other than the elevation control point +1000m line, as the basis for structural construction, building installation elevation and decoration stage elevation control.

6.1.5. Above-ground structural engineering surveys.

1) Layout of plane axis control points.

At 0The embedded parts are embedded in advance at the 000m floor position, and are firmly welded with the floor reinforcement as a reference control point. The embedded iron parts are made of 100 100 8mm thick steel plates, and 12 steel bars are welded under the steel plates, and they are welded and poured with the first floor slab.

After the embedded parts are buried, the vertical and horizontal axes where the internal control points are located are projected to the embedded iron parts respectively, and the coordinates are checked, and the accuracy is qualified as the basis for plane control, see Figure 61-8。

When pouring concrete roof on each floor corresponding to the reference control point, a hole of 200mm 200mm is reserved on the vertical corresponding control point position, so that the axis is projected upward, see Figure 61-9。

2) Control point transfer principle.

In order to ensure the plumb of the floor, each projection is measured with 0The point on 00 is used as the reference, and the control point is transmitted to the construction layer using a plumb meter to control the axes of the construction layer. In order to avoid the accumulation of errors, it is not allowed to upload layer by layer.

3) Floor axis transfer.

The laser straightener is erected on the datum point of the first floor, after centering and leveling, turn on the power supply, move the receiving target, make the target coincide with the laser beam, turn the lead straightener 180 degrees, see whether the center of the laser beam coincides with the center of the laser target, if not, take the center of the two points as the floor control point.

In order to effectively control the axis error within the allowable range, and to achieve that the structural control line can still be based on the decoration stage, it is required to pop up the detail control line, all detail axes, wall edges, door and window openings in the pay-off of the construction layer.

1) Pay-off of the construction layer.

When the construction layer is laid out, the axis of the projection is checked on the structural plane first, and then the details are laid out after closing. The interior should take the contour axis of the building as the key part.

2) Elevation measurement.

1) Establishment of elevation datum points.

Elevation measurement reference points are established on the first floor, and the level is used to guide and measure by the elevation measurement control points in the construction site, and the starting elevation is used after the verification is qualified.

2) Elevation transfer.

The total station ranging (using the reserved hole projected by the plane axis) is used for elevation transmission, and the traditional steel ruler distance measurement method is used for verification. Compared with the traditional steel ruler to transmit the elevation, the total station ranging method has the characteristics of high precision and high accuracy. The specific operation is as follows: set up a total station on the plane control point on the first floor, and set up a reflector on the corresponding point of the measured floor. The elevation of the center of the instrument is determined by setting up the station freely, and then the total station is rotated to aim upwards at the reflector, and the vertical vertical distance is measured to obtain the elevation of the reflector, and then the elevation of the reflector is transmitted to the outer wall of the shear wall with a level. Generally, three points are measured for verification, and the average value is taken as the basis for the elevation control of the layer within the error range.

1) Restoration and introduction of the axis.

Before the axis is restored, the relative distance and angle of each axis are checked, the attachments of the surface layer are cleaned up, and the ink line is re-ejected for the plane position control of the partition wallThe axis of the column façade is guided by the restored axis, and the ink line is ejected and marked with red paint;According to the restored axis and the relationship between the partition wall line and the axis line on the drawing, the partition wall line of each floor is released in turn, and the ink line is popped up.

2) Elevation measurement.

0.The 500m line is easy to cause errors due to the low height in the decoration project, and the decorative line is generally set at 1000m, which can provide convenience for determining the elevation during construction.

Floors +1Before 000m copying, the elevation control point of the structure construction is transmitted from the first layer to the core tube wall with a level, and when the difference is less than 3mm, the average elevation is taken to measure the horizontal line. Floors +1000m line copying, the laser leveler is placed in the center of the measurement point range, and the decorative horizontal line in each construction area is copied and marked with ink line.

Since the deformation observation and settlement monitoring of this project are carried out by the third-party testing unit entrusted by the owner, the specific requirements and implementation rules are detailed in the observation plan provided by the third-party testing unit.

Measurement is the key link of quality, is to ensure the normal construction of the premise of the project, in order to ensure the quality of the measurement results, the following assurance measures are formulated:

1) Surveyors hold certificates, regularly train surveyors, learn specifications, check standards, be familiar with drawings, strengthen the operational level and theoretical level of surveyors, strengthen the quality awareness of operators, measurement work is the premise and key to all other work, surveyors must be careful, patient, and check more to ensure that there are no errors in measurement.

2) The measuring instruments and equipment used on site should be inspected, maintained, maintained and recorded in accordance with the provisions of the "Measures for the Management of the Use of Measuring Instruments", and the instruments and equipment should be sent for inspection, repair or sealed and scrapped immediately after the problems are found, and unqualified instruments are not allowed to be used in the project.

3) Data collection, transmission, processing are carried out by software, the computer and the measuring instrument are connected, the data is directly imported into the instrument, the measured data of the instrument is also directly saved in the fuselage memory, directly through the cable into the computer after returning to the industry, through the measurement of the special software on the CAD drawing or through the Excel** output, the whole process as far as possible to avoid manual input, note-taking, to prevent input, recording errors. The formed data should be sorted out as soon as possible, the results should be calculated, the calculation results should be reviewed, and the errors should be corrected immediately.

4) The surveying technical supervisor arranges the on-site surveying pay-off work according to the construction schedule, the measurement plan and the requirements of the surveying plan, and makes the construction survey log. The plan and measurement method should be scientific and reasonable, and the measurement plan of the important sub-project or sub-project shall be prepared by the measurement technical supervisor and approved by the chief engineer of the project before it can be implemented.

Related Pages