A method for projecting and measuring the main control axis of a narrow and deep foundation pit
Through the combination of multi-level control outlets, GPS and total station coordinate staking methods, the problems of inaccurate measurement of main control axis and reduced accuracy in narrow and long foundation pits are solved, and more efficient construction measurement is achieved.
Patent Information
- Application Number
- CN202411338181.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-25
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2044-09-25
AI Technical Summary
In the construction of narrow and long foundation pits, the traditional external control method main control axis measurement method has caused the elevation angle of the instrument to be too small due to the too deep and narrow foundation pits, and the line of sight is blocked, so the accuracy cannot be accurately measured and the accuracy is reduced, which cannot meet the construction measurement requirements.
The multi-level control outlet method is adopted, including determining the first-level, second-level and third-level control outlets, and through GPS static measurement and total station coordinate staking method, multiple base points for measurement and main control axis points to be measured, and mutual verification is carried out. and re-test correction to ensure the accuracy and integrity of axis projection.
The accuracy and efficiency of construction measurement are improved, and the errors caused by repeated angle and distance measurement are avoided. The measurement can be completed with a theodolite, which greatly improves the construction efficiency.
Smart Images
Figure CN118855011B_ABST
Abstract
Description
Technical Field
[0001] The disclosed embodiments relate to the field of building construction technology, and in particular to a method for projecting and measuring the main control axis of a narrow and deep foundation pit. Background Art
[0002] There are two methods for axis projection in construction surveying, one is the "internal control method" and the other is the "external control method". The external control method is used in the construction of basic underground structures. When the foundation pit is excavated in the last step, the main control axis control points should be arranged outside the foundation pit, generally one meter away from the axis. When the foundation pit is excavated to the bottom elevation of the trench, a theodolite should be set up on the axis control point outside the foundation pit to project into the foundation pit. The axis is projected onto the construction surface to check the position deviation of the building's positioning size, sump, elevator shaft, etc. After the concrete of each floor slab of the basement is poured, the first step is to project the main control axis. The basement usually uses the external control method for projection, with no less than two lines in each section, which must be closed with the previous section. After meeting the requirements, other detailed lines such as wall columns, door and window opening lines and template control lines can be placed.
[0003] When encountering a long and narrow deep foundation pit, continuing to use the traditional external control method to project the main control axis will result in the main control axis being unable to be fully projected on the construction surface due to the deep foundation pit. The instrument will be placed at the control point outside the foundation pit, resulting in a small elevation angle and obstructed line of sight. In addition, since the foundation pit is too long and narrow and there are too many construction flow sections, the accuracy of the main control axis will decrease. Therefore, this single projection method cannot meet the requirements in this special foundation pit project. It is now urgently necessary to invent and research a new projection method to meet the construction measurement accuracy requirements for this long and narrow deep foundation pit project. Summary of the invention
[0004] In view of this, an embodiment of the present disclosure provides a method for projecting and measuring the main control axis of a long and narrow deep foundation pit, which solves the problem in the prior art that the projecting and measuring of the main control axis is not accurate and comprehensive when encountering a long and narrow deep foundation pit.
[0005] In a first aspect, an embodiment of the present disclosure provides a method for projecting a main control axis of a narrow and deep foundation pit, comprising the following steps:
[0006] Determine the first-level control network points, wherein the first-level control network points include the first-level measurement base points;
[0007] Determine the secondary control network points according to the primary control network points, the secondary control network points include four secondary survey base points, and two secondary survey base points are set on both sides of the foundation pit;
[0008] The tertiary control network points are determined based on the secondary control network points. The first main control axis point to be measured is obtained based on the two secondary measurement base points on one side of the foundation pit. The second main control axis point to be measured is obtained based on the other two secondary measurement base points on the other side of the foundation pit. The first main control axis point to be measured and the second main control axis point to be measured are cross-checked to obtain the tertiary control network points.
[0009] Furthermore, the axes are projected on each other at the first main control axis point to be measured and the second main control axis point to be measured. If the deviation of the projected main control axis exceeds a threshold, the three-level control points are re-measured and corrected.
[0010] Furthermore, determining the secondary control network points based on the primary control network points includes: using two primary survey base points as survey base points for the secondary control network points, surveying and setting up the secondary control network points at the construction site, and obtaining the secondary control network points.
[0011] Furthermore, after each underground concrete floor is poured, the tertiary control points are determined based on the secondary control points.
[0012] Furthermore, the coordinate points of each main control axis are measured and set at the edge of the crown beam of the foundation pit by using the secondary control points through the total station coordinate layout method to obtain the tertiary control points.
[0013] Furthermore, the total station coordinate layout method is used to set up a total station on one of the secondary survey base points of the secondary control network points, and the other secondary survey base point at the farthest end is looked back to lay out the main control axis points to be measured. After all the points are laid out, they must be closed with the third secondary survey base point to obtain the first main control axis point to be measured.
[0014] Furthermore, the secondary control network points are measured statically using GPS, and the coordinates of the secondary survey base points are calculated after data adjustment.
[0015] Furthermore, the primary control points are used to determine the secondary control points through the GPS static measurement method.
[0016] Beneficial effect: When the floor plan needs to be laid out and the axis needs to be projected, it is only necessary to set up the instrument on the measured axis point, look back at the direction line, and project directly into the foundation pit, avoiding the errors caused by repeated angle and distance measurements, and it can be completed using the most primitive theodolite, greatly improving construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0018] Figure 1 A flow chart of a method provided in accordance with an embodiment of the present disclosure.
[0019] Figure 2 A planar control network layout diagram provided for an embodiment of the present disclosure.
[0020] Figure 3 This is an example diagram of the first step of axis projection provided in an embodiment of the present disclosure.
[0021] Figure 4 This is an example diagram of the second step of axis projection provided in an embodiment of the present disclosure. DETAILED DESCRIPTION
[0022] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.
[0023] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.
[0024] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein may be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein may be implemented independently of any other aspect, and two or more of these aspects may be combined in various ways. For example, any number of aspects described herein may be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein may be used to implement this device and / or practice this method.
[0025] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present disclosure. The drawings only show components related to the present disclosure rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.
[0026] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects described may be practiced without these specific details.
[0027] The following is an example of a construction project in Haidian District, Beijing.
[0028] This specification provides a method for projecting the main control axis of a narrow and deep foundation pit. Figure 1 , Figure 2 and Figure 3 As shown, the following steps are included:
[0029] S1. Determine the primary control network points, wherein the primary control network points include the primary measurement base points;
[0030] In a possible implementation, when selecting the first-level control network points, attention should be paid to the location of the selected points, which should be close to the construction site and in an open area around it. There should be no less than three points. After the construction unit and the construction unit complete the handover of the measurement points, the construction unit's measurement personnel should be organized to re-measure the points. If any problems are found, the points should be re-measured in time. If the accuracy of the re-measured points meets the specifications and design requirements, the construction unit should protect the points and use them directly as the first-level plane control network of the project. This project provides 3 measurement control benchmarks (reference points), which are located on the road outside the construction site. The distance between K1 and K2 is 169.581m, and the distance between K2 and K3 is 123.514m. The point errors after re-measurement are as follows:
[0031]
[0032] From the table data, we know that the point errors are all within ±3mm, which meets the specifications and design requirements, that is: K1, K2, and K3 are used as the first-level control points of this project.
[0033] S2. Determine the secondary control points according to the primary control points, wherein the secondary control points include four secondary survey base points, and two secondary survey base points are respectively set on both sides of the foundation pit;
[0034] In a possible implementation, the first-level control network uses three first-level survey base points (K1, K2, and K3). After re-survey, the accuracy requirements are met. K3 and K1 in the first-level control network are used as survey base points to survey and set up second-level control network points (2JK-1, 2JK-2, 2JK-3, and 2JK-4) at the construction site. In order to ensure accuracy, the second-level control network uses GPS static measurement, and the point coordinates are calculated after data adjustment.
[0035] For example, to ensure the measurement accuracy of the secondary control points, the GPS static measurement method is used. This method has the advantages of short operation time, high precision, avoiding tedious internal calculations, and not being blocked by sight. Static measurement is usually completed by a group (at least three) of GPS receivers at the same time, that is, the instruments set up at known points and unknown points are turned on at the same time to collect data, and after the collection is completed, they are turned off at the same time. The main process is: lay out control points - place receiving 8u machines - turn on - select static measurement mode - measure instrument height - turn off - data processing - adjustment report.
[0036] In this embodiment, four secondary control points are selected, and two sets of GPS are respectively set up on four unknown points and two known points. The data is statically collected for 30 minutes based on the last startup time, and finally the three-dimensional coordinate data of the control points are obtained through data processing.
[0037] The selection of control network points should meet the following conditions: the points should be located in the corners of the construction site, where it is easy to place the receiving equipment, and the field of view should be wide; GPS points should avoid objects that interfere with electromagnetic wave reception, such as microwave stations, TV stations, high-voltage lines, etc.; the distance difference between control points should not be too large, and the stability of the graphics should be met.
[0038] GPS receiver placement: includes centering, leveling and measuring antenna height. The antenna height is generally measured from the slant distance from the measuring mark on the receiver to the center of the ground measuring point mark. During the adjustment process, the software will automatically convert it into the vertical distance from the phase center of the GPS antenna to the center of the observation point mark.
[0039] Observation work: The main task is to capture GPS satellite signals, track, receive and process them to obtain the required positioning information and observation data. After the GPS receiver is installed, turn on the power at the agreed time and start the receiver for observation.
[0040] Observation records: There are two forms: (1) automatically generated by the receiver and stored in the receiver memory for easy access and processing; (2) measurement notebooks, filled in by observers, mainly including instrument number, station name, antenna height, and power on / off time. Observation records are the original data of GPS positioning and the only basis for subsequent data processing. They must be true and accurate.
[0041] Data processing: The internal data processing process can be roughly divided into: preprocessing, coordinate system conversion, baseline processing, adjustment calculation, and results reporting.
[0042] S3. Determine the tertiary control network points based on the secondary control network points, obtain the first main control axis point to be measured based on the two secondary measurement base points on one side of the foundation pit, and obtain the second main control axis point to be measured based on the other two secondary measurement base points on the other side of the foundation pit, and cross-check the first main control axis point to be measured with the second main control axis point to be measured to obtain the tertiary control network points.
[0043] In a possible implementation, a total station is set up on one of the secondary survey base points of the secondary control network using the total station coordinate layout method, and the other secondary survey base point at the farthest end is rear-viewed to lay out the main control axis points to be measured, and after all are laid out, they are closed with the third secondary survey base point to obtain the first main control axis point to be measured. The second main control axis point to be measured can be measured in the same way.
[0044] For example: the third-level control network is the axis control grid. The third-level control network is laid out using the total station coordinate layout method. A total station is set up on the secondary survey base point (2JK-1) of the secondary control network point, and then the farthest secondary survey base point (2JK-3) is looked back to lay out the main control axis points to be measured. After all the points are laid out, they must be closed with the third secondary control point (2JK-2).
[0045] It should be noted that the preparation work of the three-level control network before measurement is particularly important. First of all, it is necessary to ensure that the measured point is 50cm away from the foundation pit, and the error should not be too large or too small. If it is too large, the construction surface will not be visible when projecting the axis into the foundation pit. If it is too small, the measuring instrument cannot be set up. Since the distance to the foundation pit is too small, getting close to the foundation pit will also affect one's own safety. In order to ensure the best distance, first use GPS dynamic measurement (RTK) to collect data along the edge of the foundation pit, confirm the actual position of the foundation pit, use CASS software to display the data, and use CAD to draw the actual foundation pit position in the construction drawing. At the position where the axis control point needs to be measured, the actual foundation pit position line is offset 50cm outward to obtain the best point position on the construction site. The coordinates of each axis control point can be captured through CAD software.
[0046] In order to ensure the accuracy and stability of the main control axis projection measurement, it is proposed to adopt the "external control method" to measure in opposite directions (that is, set up instruments at both ends of the foundation pit for projection measurement, see Figure 3 and Figure 4) and use the total station to track and measure, and the two methods are checked against each other. Since the foundation pit is about 280 meters long from east to west, 7 axis control lines need to be laid out according to the flow section. The opposite projection method will increase the number of control points to be laid out. Too much angle measurement and distance measurement will lead to a decrease in point position accuracy and instability. In order to ensure the accuracy and accuracy of the projected axis control line, it is also necessary to complete the projection of the axis on the working surface through the opposite projection method after the pouring of each underground concrete floor slab is completed. Then, the coordinates of the intersection position of each axis are laid out by the total station set up on the secondary control point using the coordinate projection method, so as to check against the projected axis control line. If it is found that the projected axis deviation is not within the threshold, the third-level control network point, that is, the axis control point, should be re-measured and corrected. The opposite projection method is fast and simple and should be the first choice. It can effectively cope with tight schedules and heavy tasks.
[0047] Preferably, after each underground concrete floor is poured, the tertiary control points are determined based on the secondary control points.
[0048] Preferably, the secondary control points are used to obtain the tertiary control points by measuring and setting each main control axis coordinate point at the edge of the foundation pit crown beam through the total station coordinate setting method.
[0049] It should be understood that various parts of the present disclosure may be implemented in hardware, software, firmware, or a combination thereof.
[0050] The above is only a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present disclosure should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.
Claims
1. A method for projecting and measuring the main control axis of a narrow and deep foundation pit, characterized in that: The following steps are involved: Determine the first-level control network points, wherein the first-level control network points include the first-level measurement base points; Determine the secondary control network points according to the primary control network points, the secondary control network points include four secondary survey base points, two secondary survey base points are set on both sides of the foundation pit, the secondary control network points are measured by GPS static measurement, and the coordinates of the secondary survey base points are calculated after data adjustment; Determine the third-level control network points based on the second-level control network points, obtain the first main control axis point to be measured based on the two second-level survey base points on one side of the foundation pit, and obtain the second main control axis point to be measured based on the other two second-level survey base points on the other side of the foundation pit. Verify the first main control axis point to be measured with the second main control axis point to obtain the third-level control network points; ensure that the measured point is 50cm away from the foundation pit, first use GPS dynamic measurement (RTK) to collect data along the edge of the foundation pit, confirm the actual position of the foundation pit, display the data with CASS software, and draw the actual foundation pit position in the construction drawing with CAD. At the position where the axis control point needs to be measured, offset the actual foundation pit position line outward by 50cm to obtain the best point position on the construction site. The coordinates of each axis control point can be captured by CAD software; In order to ensure the accuracy and stability of the main control axis projection, it is proposed to adopt the "external control method" for opposite projection and use the total station for tracking measurement, and the two methods will be calibrated against each other.
2. A method for projecting and measuring the main control axis of a narrow and deep foundation pit according to claim 1, characterized in that: The axes are projected mutually at the first main control axis point to be measured and the second main control axis point to be measured. If the deviation of the projected main control axis exceeds the threshold, the three-level control points are re-measured and corrected.
3. A method for projecting and measuring the main control axis of a narrow and deep foundation pit according to claim 1, characterized in that: Determining the secondary control network points based on the primary control network points includes: using two primary survey base points as survey base points for the secondary control network points, surveying and setting up the secondary control network points at the construction site, and obtaining the secondary control network points.
4. A method for projecting and measuring the main control axis of a narrow and deep foundation pit according to claim 1, characterized in that: After the pouring of each underground concrete floor is completed, the tertiary control points are determined based on the secondary control points.
5. The method for projecting and measuring the main control axis of a narrow and deep foundation pit according to claim 1 is characterized in that: By using the secondary control network points and the total station coordinate layout method, each main control axis coordinate point is measured and set at the edge of the foundation pit crown beam to obtain the tertiary control network points.
6. A method for projecting and measuring the main control axis of a narrow and deep foundation pit according to claim 1, characterized in that: Use the total station coordinate layout method to set up the total station on one of the secondary survey base points of the secondary control network points, look back at the other secondary survey base point at the farthest end, and lay out the main control axis points to be measured. After all are laid out, they must be closed with the third secondary survey base point to obtain the first main control axis point to be measured.
7. A method for projecting and measuring the main control axis of a narrow and deep foundation pit according to claim 1, characterized in that: The secondary control network points are determined by using the primary control network points through GPS static measurement method.