Application of GPS technology in bridge surveying and mapping engineering?

How to apply GPS technology in bridge surveying and mapping engineering? What are the advantages? Please read the article edited by Zhong Da Consulting Company.

With the development of bridge and surveying and mapping industry, more and more high and new technologies are applied to bridge surveying and mapping engineering. The application of GPS technology not only effectively improves the efficiency of surveying and mapping, but also can solve the problems that traditional surveying and mapping technology can not solve. According to the author's working experience for many years, this paper firstly summarizes the GPS surveying and mapping technology, then analyzes and discusses the advantages and application points of GPS technology, and expounds the application of GPS technology in bridge surveying and mapping engineering.

Bridge engineering is large in scale and takes a long time, so it is impossible to use conventional survey methods for bridge mapping. Therefore, it is necessary to use GPS technology to carry out bridge surveying and mapping operations, so as to solve the construction survey problems that can not be solved by conventional leveling and ensure the smooth development of bridge engineering.

Overview of 1GPS surveying and mapping technology

GPS is the abbreviation of GlobalPositioningSystem, which is called Globalpositioning System in English. The system is a satellite navigation and positioning system developed by the U.S. Department of Defense in the 1970s, which can be used for civil and military purposes. The US government announced that the system was established and put into operation in April, 1995. The system mainly uses satellites to realize positioning and navigation. Compared with the traditional positioning technology, the system has the advantages of all-weather, real-time, global, omnipotence and continuity, as well as outstanding anti-interference performance and strict confidentiality. The appearance of the system has brought fundamental changes to navigation technology and positioning technology all over the world, and has brought great influence in military affairs and various fields of people's production and life.

It is precisely because of the good characteristics of GPS positioning system that it is widely used in various survey fields, including urban survey, engineering survey, geodetic survey, aerial photogrammetry and so on. , opened a new chapter in China's surveying and mapping business. GPS is mainly composed of three parts: space satellite constellation, ground monitoring station and user equipment. Compared with conventional measurement methods, the system has the advantages of high measurement accuracy, no visibility between stations, short observation time, simple instrument operation, all-weather function and providing three-dimensional coordinates. The satellite constellation design of GPS consists of 24 satellites (in fact, 27 ~ 32 satellites are often maintained at present). They are distributed in six orbits with an interval of 60 and an inclination of 55, and four satellites are evenly distributed on each orbital plane. The altitude of this satellite on the ground is 20200 kilometers.

The satellite constellation redistributed by GPS can ensure that four or more satellite signals can be received at the same time in any time period and location, thus realizing real-time positioning observation. The difference is the relative positioning between two or more stations. Figure 1 is a schematic diagram of differential GPS. Points A and B in 5438+0 in Figure 65 can observe at least 4 satellites in the same group at the same time. As a known point, point A can transmit the original information to point B through the data link, so that the specific location of point B can be accurately determined. Global Positioning System (GPS) was put into various fields of civil use in 1980s, especially in surveying and mapping industry. At the same time, with the continuous improvement of various surveying and mapping needs, the traditional triangulation method can no longer meet the needs of the surveying and mapping industry, and the characteristics of global positioning system such as high efficiency, all-weather and high precision have gradually achieved very remarkable results in the surveying and mapping industry.

Advantages of 2GPS technology in bridge engineering survey

1) can save a lot of money, material resources and manpower for the bridge surveying and mapping department. Compared with traditional mapping technology, GPS has higher measurement efficiency and higher measurement accuracy. In the bridge surveying and mapping operation, under the condition of complex terrain, the traditional survey technology lacks certain anti-interference and the reliability of the survey is relatively poor. Using GPS technology, the survey can be carried out in the range of 1500m only by setting a single operation station, which effectively reduces the number of monitoring stations and surveyors. 2) The traditional surveying technology is easy to cause surveying errors, which will inevitably lead to the great rework of bridge engineering, and GPS surveying and mapping technology can effectively solve this problem. By establishing 3 ~ 4 mobile stations 1 unit, each lofting point only needs to stay for 0.5s to complete the centerline measurement of 5 ~ 10 km. 3) The degree of automation is higher, and the observation and processing are highly automated by using GPS mapping technology, which can effectively reduce the error of manual measurement and improve the accuracy of measurement results.

Application of 3GPS technology in bridge surveying and mapping engineering

In bridge engineering control survey, GPS is used to establish GPS control network, and its application mainly includes establishing plane control network and elevation control network. In bridge GPS mapping, GPS can provide three-dimensional positioning information, which can effectively solve the problem of bridge crossing river and sea. As long as the abnormal height difference of stations with certain accuracy requirements can be obtained, the geodetic height of GPS points can be converted into normal height, thus realizing the elevation control in bridge construction. The application of GPS in bridge construction control survey solves the difficult problems of offshore elevation control survey and continuous multi-span cross-sea elevation survey, and provides advanced technology for cross-river cross-sea construction.

The layout of GPS control network must be based on the requirements of bridge survey and design and the needs of bridge deformation monitoring, and strictly follow the principle of "overall control and local encryption". When choosing the location of control points, we must comprehensively consider the characteristics and needs of bridge construction, not only requiring the location of control points to be outside the construction sidewalk to meet the requirements of GPS surveying and mapping, but also ensuring intervisibility between adjacent two points as far as possible. For example, the starting pile number of a bridge is DK 172+764.830, the ending pile number is DK 173+939.400, and the span arrangement is: 12-32m simply supported beam+1-(40+64+40). Central mileage: dk173+352.115, total length of bridge 1 174.49 m ... The simply supported box girder of this bridge is prefabricated and erected, and the continuous beam is constructed by cantilever casting method.

The abutment of this bridge adopts double-line rectangular hollow abutment, and the top of abutment is inclined; Pier 1 ~ 1 1 and 16 ~ 33 are solid piers with round ends; Piers No.0 ~ No.34 are bored piles, and the bridge is located on a curve, with a double line and a line spacing of 4.6m The plane control network of the bridge adopts the GPS synchronous static observation mode, adopts the geodetic quadrilateral or triangular synchronous graphic expansion mode to arrange the network, and adopts two public stations to realize the connection between adjacent synchronous rings, which consists of about 5 stations, each synchronous ring is observed synchronously 1 cycle, and each cycle is observed.

The data conversion software provided by the receiver is used to convert GPS observation data into standard Rinex format, and then Leica LGO7.0 software is selected for baseline calculation. After the baseline calculation meets the requirements, the baseline vector file is output, and the adjustment calculation is carried out by visibility. The main technical requirements of leveling observation are strictly implemented in accordance with the specifications, and all relevant technical indicators and tolerances are set in the digital level. In the process of field observation, real-time inspection and prompt are realized through the leveling route measurement software system that comes with the instrument. As long as it is found that it exceeds the standard, it needs to be re-measured immediately to ensure the accuracy and reliability of the measured data. After the plane elevation survey is completed, the survey results shall be submitted to the supervision unit for approval in time, and can only be used after approval.

4 conclusion

To sum up, GPS precise positioning technology has many advantages such as all-weather, high precision, real-time and so on. It has been widely used in bridge surveying and mapping in China, and achieved very good surveying and mapping results, which fully proved the measurement superiority of GPS positioning technology. In the future, with the continuous development of science and technology, GPS technology will be further developed, its application scope will be wider, its measurement results will be more accurate, and it will play a greater role in the development of China's economic construction, national defense construction and scientific and technological progress.

The above are collected and sorted by Zhong Da Consulting Company.

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