The hospital project construction measurement plan is very critical. Only by recording the measurement data can we arrange the subsequent construction. Every detail must be processed to the best to ensure the quality of the project. Zhongda Consulting will explain to you the hospital project construction measurement plan.
1 General Principles
An important feature of this project is the large number of units and the complex plan layout. In order to ensure the accuracy of the plane positions of the building's axis and wall columns, it is necessary to Conduct a same-accuracy review based on the design data and the transferred control points and positioning axes. At the same time, pay attention to joint testing with neighboring national networks or local independent city networks to reflect the overall unity of urban planning.
Carefully check whether the actual deviation can meet the accuracy requirements of superstructure construction. If there are damaged or missing control piles, they must be corrected and repaired in time, and they must be surrounded and protected with brick walls.
According to the independent coordinates of the DA hospital provided by the owner, the polar coordinate method was used to accurately reflect the axis and elevation of the building during the construction process. In strict accordance with the requirements of the "Engineering Surveying Specifications", the overall and then the local In principle, the entire project should be controlled as a whole, and then the control points of each section should be encrypted and staked out.
2 Surveying and Construction Organization
2.1 Surveying Personnel
According to the overall construction deployment of this project, the construction will be organized in parallel in four areas on the plane, that is, the construction of the inpatient building area, the two construction areas of the outpatient medical technology building and the construction areas of dormitory buildings A, B, and C. Therefore, the measurement team of this project is divided into three teams, each of which is responsible for the measurement and setting out of their respective construction areas.
The following surveying personnel are invested in this project:
1 surveying engineer and 9 surveying workers.
2.2 Measuring instruments
According to the characteristics and accuracy requirements of this project, a total station is used for plane control and building positioning, a theodolite is used for axis setting, a precision level is used for elevation measurement, and a spindle Laser plummet for line verticality control. At the same time, it is also equipped with corresponding computer calculation programs for data processing in order to carry out measurement work efficiently and accurately to ensure project quality. Please see the list of measuring instruments planned for this project.
List of main measuring instruments for this project
Instrument name, model, quantity, accuracy and purpose
Total station SET2B/C12＂±(3mm+2ppm) distance and angle Measurement
3 Measurement Control
3.1 Establishment of Plane Control Network
This project is a large public construction project, consisting of the inpatient building, medical technology It is composed of three major areas: the clinic building and the staff dormitory building. There are many construction processes and the building has a unique shape. This is mainly reflected in the large single-story area of ??the building and the complex shape of the building. Therefore, it is necessary to establish a measurement control network that meets the construction requirements and can monitor the entire building. The construction area is fully controlled.
(1) The establishment of a general plane control network
In order to control the entire construction area, improve the quality, progress, accuracy, convenience, etc. of the construction. To meet the needs of all aspects and prevent the loss and damage of the original datum points, we will establish a general measurement plane control network serving the entire construction area based on the original datum points provided by Party A, and control the original datum points layer by layer.
Firstly, use a total station to locate the original datum point to a nearby place with good visibility and difficult to be damaged by human factors, and then mark it with red paint.
Secondly, Connect each lead measurement point into a closed conductor, conduct continuous measurement on each conductor point, collect control network data in the field for in-house analysis, calculate the coordinates of each conductor point in the control network, and use the error principle to analyze the error of each conductor point. The resulting error shall be evaluated within the allowable range of the measurement specification.
Angle error: ⊿α=360ο- (α?+αⅡ+αⅢ+αⅣ+αⅤ+αⅥ+αo2)
< p> Error distribution principle: The total error α is distributed to each corner in proportion according to the principle of large angle distribution. If the error value is positive, the error distribution is based on -⊿α; when the error value is negative, the error is distributed according to +⊿α. .Distance error: Due to the error in angle measurement, each control point will produce distance error and coordinate error accordingly. After the angle error is assigned to each edge, the measured distance between each edge is used. and the error angle assigned to the corresponding side to calculate the coordinate increase or decrease before correction (xi, yi).
Since the assigned angles are positive and negative, and the azimuth angles of each side are in different quadrants, the generated coordinates (xi, yi) are also positive and negative. Find the coordinate increase and decrease of each control point: fx=∑xi, fy=∑yi, and then find the vector sum generated by each control point: fi=(fx2+fy2)1/2, and further find the vector sum generated by each measured edge. Does the error comply with the closed sum difference of side lengths:
f=fi/∑s
When f is less than the specification limit difference (layed according to the first-level wire network), the collected data The result is valid, and then use the following formula to perform the adjustment:
⊿Si=si×f=si×fi/∑s
Error distribution: S=si+⊿Si
In the formula, si----the measured side length, S-----the corrected side length
When f is greater than the specification limit, the measurement should be re-measured and the adjustment calculated again. .
Finally, organize the internal data and draw the overall floor control chart.
The control network mainly controls the accuracy of the buildings in the entire construction area, which is beneficial to the layout and inspection of the axis control network for construction in each area, and improves the quality and progress of the entire project. If a major control point is damaged or lost during construction, each control point can be restored and checked against each other. The coordinates of each point have been calculated as known when arranging the control points on the general plane, so the control points lost or destroyed during construction are restored using the forward intersection method:
S=[(yii-yi)2+ (xii-xi)2]1/2
α=tg-1[(yii-yi)/(xii-xi)]
As shown in the figure below:
(2) Establishment of plane control network in each construction area
This project is divided into three construction areas, namely the inpatient building, the medical and technical outpatient building, and the dormitory building. In order to facilitate the construction flow operations, we When arranging the construction plane control network, the layout method of laying out each area separately, alternating internal and external control, large network controlling small network, layer-by-layer control, and layer-by-layer inspection is used to establish the construction area plane control network in each area.
Schematic diagram of the plane control network
According to the layout of the buildings in each district, the characteristics of the column network, and the elevation and plane characteristics of the buildings in each district, the plane control network in each district is established as follows:< /p>
According to the original reference point provided by Party A, release the building outline coordinates and use the following formula:
⊿x=X+Scosα
⊿y=Y +Ssinα
Back-calculate the coordinates of the control points on the control line, and select the location and number of control points based on the plan and section drawings of areas A, B, and C. Therefore, the number of control points must be controlled. Set out the axis of each layer, and then use a total station to accurately stake out the position of the control line and protect it. After the building is out of the ground, the control lines will be guided into the building, and corresponding control points will be prepared and protected as permanent control points in the entire construction area. Leave holes above the control points to pass the control lines and elevation. Extend two of the mutually perpendicular control lines to the road or the wall of an existing building and mark them as review points.
In addition, the entrance to the exhibition room and foyer is in the shape of a circular arc. For the column points on the arc, we cannot carry out construction stakeout through axis translation, so we can set up coordinate control points. Stake out the column points located on the arc. The control point is used as the control point to control the column point of the arc segment, and the coordinates of the control point are calculated. When setting out, coordinate setting out is carried out by calculating the coordinates of the cylinder points on each arc through control points.
The positioning of circular arc curve structures requires auxiliary point encryption for accurate positioning. We regard this as a key control link in measurement and plan to use the "central longitudinal distance method" (sagittal height method). According to the chord line and the central longitudinal distance The distance M is measured to set up the auxiliary point of the curve. The principle is to measure the midpoint of the chord line from the starting point ZY to the end point YZ of the curve. Vertically measure the mid-longitudinal distance M point to determine the midpoint QZ of the curve; then from the starting point ZY of the curve to the midpoint QZ At the midpoint of the string line, vertically measure the mid-length distance M1 of the string to measure the 1/4 point of the curve. Use the same measurement method, and so on, until the spacing between the auxiliary points of the curve can meet the needs of circular arc positioning.
Calculation formula for the corresponding distance of each point:
3.2 Detailed stakeout of each construction detail point
(1) Setout of the control axis of each floor: move the control axis from the predetermined Leave holes to lead to each floor, and release the coordinates of the axis or control points if necessary.
During each transmission, the four control points must be reviewed with each other or with the original reference point, and records must be kept. The distance, angle, and coordinates between the four points must be checked until they are fully consistent or within the allowable range of the measurement specifications.
(2) Staking out walls, columns and formwork: Stake out the positions of walls, columns, dimension lines or center points according to the control axis and coordinate control point positions, used to check the position of wall and column steel bars, and timely Correct the deviation to facilitate the positioning of the template. Then lay out the template line control line around it (the control line is generally 20cm away from the outside of the structure). Put
Double-line control to ensure the cross-sectional size and position of walls and columns. Then release the center line of the column, and after the column is removed from the template, lead this line to the column surface to determine the position of the upper beam.
(3) Setting out beams and slabs
After the walls and columns are removed from the formwork, carry out elevation transfer and immediately use ink lines to pop up the +0.50M line on the walls and columns without leakage Then, according to this line, the beam, slab bottom and formwork lines can be measured upward.
(4) Setting out doors, windows and openings
While placing the wall lines, pop up the plane position of the door and window openings, and then set out the window openings on the tied steel cage. The height, marked with paint, is placed to form the form for the window opening. The vertical pop-up lines of exterior wall doors, windows and openings are checked against the plane position to control the position of doors, windows and openings.
(5) Setting out the stair treads
According to the design size of the stair treads, use ink lines to pop up on the walls on both sides of the actual position, and pop up two parallel lines at the ladder corners to facilitate correction. .
3.3 Elevation measurement
Since the construction area occupies a relatively large area and the construction area is large, it is difficult to use one or two original level points, so it must be measured throughout the construction area. Lay out a horizontal net to meet the needs of areas A and B.
Set density leveling points H1, H2, H3, H4, H5 in places around the foundation pits in areas A and B that will not affect construction, have good visibility, are easy to preserve, and have solid geology, according to Level IV Measurement methods are used to establish an elevation control network. The elevation is measured from the original level point to each refined level point, and closed with the original level point to form a closed level line. Perform internal analysis on the data collected by the outside industry, the total error is:
⊿h=h1+h2+h3+h4+h5+h6h1…---------- is the encryption level Height difference between points
The limited error for fourth-grade leveling measurement is: 20√S or 5√n, unit: mm
S----- is the closed level The number of kilometers of the route, n------ is the number of measurement stations for round-trip measurement
Analyze the total error of the above measurement settings. If the error exceeds the construction measurement error limit, the result will be invalid, and the measurement and design will be re-measured. If the error is within the construction measurement error limit, the error distribution principle will be used to perform adjustment processing for each encrypted level point:
Distance adjustment
⊿h1=s1×⊿h/(s1+s2+s3+s4+s5+s6)--------si is the distance between adjacent encryption level points Distance
⊿h2, ⊿h3, ⊿h4, ⊿h5, ⊿h6 are the same as above.
Station adjustment
⊿h1=n1×⊿h/(n1+n2+n3+n4+n5+n6)-------ni is adjacent The number of encryption leveling point measurement stations
⊿h2, ⊿h3, ⊿h4, ⊿h5, and ⊿h6 are the same as above.
Then the elevation of each encryption level point is:
H1=H+h1-⊿h1
H2=H+h1+h2-⊿h1-⊿ h2
…….
H=H+(h1+h2+…+h6)-(⊿h1+⊿h2+…+⊿h6)=H
at During construction, the level points of each area are measured from the corresponding encrypted level points to the pillars or walls, and their elevations are drawn with red paint and marked. As the permanent elevation point of the area, a reserved hole is left directly above it. The reserved hole is measured with theodolite and steel ruler, and a permanent floor elevation datum point + 1.000M elevation point is set for each floor, which is marked with red Paint markings shall not be covered or destroyed without permission. After that, use a theodolite on each floor to draw a long straight line along the vertical direction of the pillar or wall at the reserved hole. To eliminate the vertical error of the steel ruler. In order to avoid cumulative errors caused by the number of transmissions as much as possible, the elevation was re-measured every three floors during construction to correct the errors in a timely manner.
Allowable deviation in elevation: floor height shall not be greater than 10mm, and total height shall not be greater than 30mm. As shown in the figure:
3.4 Error basis
Based on the current national standards of the People's Republic of China "Engineering Measurement Specifications" and "Construction and Installation Engineering Quality Inspection and Assessment Standards".
3.5 instruments
(1) Japanese-made TOPCON301D total station, angle measurement accuracy 2", distance measurement accuracy 5mm2ppm. Mainly used for general plane control points and small construction area control points Positioning, coordinate setting out, detection and overall displacement and verticality control of the building.
(2) Swiss-made Leica optical plumbometer, with a measurement accuracy of 2mm/km, mainly used for floor control points.
(3) LETAL3200 automatic leveler produced in Tianjin. The measurement accuracy is 1mm/km. It is mainly used for the measurement and installation of construction control network, floor elevation, settlement observation and detection. /p>
(4) Laser theodolite. The measurement accuracy is 1/20000.
(5) The domestic Suguang J2 theodolite has an angle measurement accuracy of 2". It is mainly used for setting out the axis of each floor and working with the plumb meter for control point detection.
(6) 50m steel ruler. Mainly used for measuring distances and measuring elevations with a level.
3.6 Settlement Observation
(1) Characteristics of Settlement Observation
High accuracy: In order to accurately reflect the deformation of the building, the measurement error is generally specified It should be less than 1/10-1/20 of the deformation. For this reason, precision levels S1 and S05 and precise measurement methods should be used in settlement observation.
(2) Settlement observation method
According to the actual conditions on site, select a strong and stable place in the building, bury the settlement observation points according to the designed settlement observation point layout, and match the settlement observation points away from the site. Points farther away from the building that are easy to observe and strong and stable form a closed horizontal line to ensure the accuracy of the observation results. When the foundation slab is poured, temporary observation points are buried at the positions specified in the design. Set observation points along the vertical and horizontal axes and around the foundation. The number and time of observations should be in accordance with the design requirements. The first observation should be carried out in time after the installation of the observation point is stable. In the future, every time the structure is raised one floor, the temporary observation point will be moved to the next floor and the observation will be carried out until ±0.000, and then the permanent observation point will be buried according to regulations. Then, re-test each layer of construction until completion. After the project is completed, it will be tested four times in the first year, twice in the second year, and once a year after the third year until the subsidence is stable.
(3) Selection and arrangement of benchmark points
To achieve the settlement changes of the settlement observation points, there must be some fixed (relatively fixed) points as benchmarks. According to them, To measure, in order to obtain the required displacement value.
After the construction of an engineering building, the stress in the surrounding area changes with the change of the horizontal distance and vertical distance (depth) away from it. The further away from the building, the greater the depth, and the smaller the stress on the foundation, which means the less impact it will have on the building. In order to achieve the requirement of stabilizing the reference point, there are two methods: one is to stay away from the engineering buildings, and the other is to bury it deeply. However, if the reference point is far away from the building, the measurement workload will increase, the accumulation of measurement errors will also increase, and the reliability of the measured displacement value will be small; if the mark is buried very deep, it will be labor-intensive and It is also wasteful and uneconomical. The selection of datum points and the layout of the control network should be comprehensively considered and reasonably solve the problem of datum point layout as the basis for deformation observation. Specific method: bury steel bars about 1 meter long at the selected appropriate location and secure them for protection. In order to check whether the elevation of the horizontal base point itself has changed, it can be buried in groups, usually three points in each group, and form an equilateral triangle, as shown in the following figure:
At the center of the triangle, with A fixed measuring station is set up at an equidistant location between three points, so that the height difference between the three points can be frequently observed at the measuring station, so that it can be judged whether there is any change in the elevation of the horizontal base point.
(4) Accuracy requirements and observation methods for engineering settlement observation
Elevation error: ±2.0mm
Adjacent point height difference error ±1.0mm
Observation method: third-class leveling measurement
The leveling line for settlement observation (from one leveling point to another leveling point) should form a closed line, as shown in the following figure: compared with the general Compared with the level measurement, the difference is that the sight length is shorter; generally not more than 25m, and the instrument can be placed at several forward sight points at one time. In different observation periods, the instrument should be placed at the same position to weaken the influence of systematic errors. Since the leveling line during observation is often not long, and its closure and difference generally do not exceed 1-2mm, the closure and difference can be evenly distributed according to the measuring station. If the distances between observation points vary greatly, the sum and difference can be distributed proportionally to the distance.
Round-trip difference, echo or loop closed sum difference: 1.4√n
(5) Result data of settlement observation
Building plan
The subsidence statistics table (see attached table) is a summary of the subsidence and accumulated statistical values ??of each observation point based on the original settlement observation records.
Subsidence curve of measuring points
(6) Basic measures for settlement observation
Stability: Stability refers to the reference point on which settlement observation is based, The working base point and the settlement observation point on the object to be observed must be stable. The benchmark point is the basic basis for settlement observation. This project must have at least 3 stable and reliable benchmark points, and the benchmark points shall be re-measured every six months; the working benchmark point is the basis point directly used in the observation, and should be selected close to the observation point but relatively A stable place.
Four fixations: Four fixations means that the instruments and equipment used must be fixed; the observers must be fixed; the observation conditions and environment are basically the same; and the observation routes, mirror positions, procedures and methods must be fixed.
(7) Arrangement and practice of observation points.
Observation point on the reinforced concrete column: Drill a hole 10~50cm above the ±0.000 elevation of the column (or leave a hole during prefabrication), insert the angle steel with a cross-section of 30x30x5mm and a length of 160mm into the hole. In the middle, make it form an inclination angle of 60° with the column surface, and then fill it with 1:2 cement mortar. As shown below:
Observation points on reinforced concrete foundation: According to the location of the arranged observation points, use rivets with a diameter of 20mm and a length of 60mm, weld a 40mm×40mm×5mm steel plate, and bury it on the foundation surface. superior. As shown below:
3.7 How to control points and reserved holes
(1) Reserved holes: Reserve corresponding holes on each layer directly above the control points and corresponding axis control points A number of 300mm and 300mm reserved holes should be reserved, and a 300mm and 300mm reserved hole should be reserved close to the corner of the wall or column. Cover it with a special cover when not in use to protect it and prevent falling objects.
(2) Control points
General plane control points: After the measurement and setting of the general plane conductors, use a cross gantry to control the position of the measured points. Prefabricated cement piles are buried in the position. The method of making prefabricated cement piles is to use thick steel bars with a diameter of 30mm, grind the upper end flat, facet cross lines on the upper end as a mark, bend the lower end into a hook shape, and pour it into concrete. The pile top size is 150mm×150mm, and the pile bottom size b and burial depth c are determined according to specific conditions. After the pit is dug, cement piles are poured into it. Before the cement solidifies, the gantry is used to control the position of the steel bars to the original position. The schematic diagram is shown below:
Construction area axis control points: After the ±0.000 layer is completed, a corresponding number of control points will be made on the control line according to the requirements of segmented construction. Since the axis control points control the measurement work of the entire construction section, the points must be corrected or adjusted, so the stake types are different from the wire points. Place a 100mm × 100mm × 10mm steel plate on the top of the stake. An anchor hook is welded under the steel plate, and then embedded in the concrete of the pile body to be used as an adjustment point. When calibrating the final point on the target plate, it is best to drill a small hole with a diameter of 1~2mm on the steel plate and draw a cross line through the center. Use red paint to draw a circle around the small hole to make the spot eye-catching and protect it. Covering, hitting or other deliberate damage without permission is not allowed.
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