| Due to some inevitable factors such as high risk of metro constructing, non-objective awareness of construction safety and non-scientific management system and so on, serious safety accidents frequently occurred, which causes vicious influence and great economic losses. In March,2007, gas pipe was broke when constructing Nanjing metro line. Then gas spilled leading to explosion and fire. A similar case happened in Beijing, the casualty was 6 in metro construction. The most serious economic loss was Shanghai Metro Line No.4 accident, which caused about 0.6 billion RMB loss. Actually, almost each metro tunnel caused casualties in long and big tunnel construction. Therefore, metro construction security becomes an increasingly worthwhile question to be further studied with the high rapid development of modern urban metro construction.Urban metro construction security has two meanings. On one hand, it means surveying security, that is to say, metro tunnel has to smoothly breakthrough at the specific sites according to design acquirements. On the other hand, it indicates safety monitoring, which stands for rock deformation and disturbance during the construction period caused by underground excavation. As the consequence, horizontal movement and settlement occur in the subway structure engineering and construction orientation line or around or underground, ground structures, important pipe lines, roads and so on, during which timely monitoring should be taken to protect surrounding environment.Metro construction security depends on breakthrough surveying technology and surveying management. Breakthrough surveying technology aims at controlling tunnel constructing direction depends on ground control surveying, contact surveying and tunnel traverse surveying technology. An important basis of tunnel breakthrough is correct surveying project, reliable surveying results of high-precision. Viewing from metro surveying management pattern, the construction surveying team, the employer surveying team and the third-party surveying team are all required a second time surveying of ground control surveying, contact surveying and underground traverse surveying. As a result, the surveying results have to turn over to clients and be inspected before being used. The inspection program is complicated, which will cause hidden dangers in metro construction for example sometimes the inspection may be omitted due to construction schedule. By observing monitoring points on deformation body, safety monitoring aims at monitoring any changes of building structure and metro construction surrounding environment. Thus, surveying security (breakthrough technology and surveying management) and safety monitoring are vital to metro construction security. This paper theoretically derived from major factors affecting metro construction surveying security and further studied from the prospective of major error resources affected breakthrough. With the existed problems of metro construction in mind, this paper studies networking metro management pattern based on full using of network resources. Develop safety monitoring system integrating construction designs and monitoring analysis by use of.NET,.ASP, Sliverlight, C#, ArcGIS Server, ArcSDE, SQL Server technology.This paper has concluded the following highlights:1. Error computed model of underground traverse with additional gyroscope orientation is developed in the process of ground control surveying, contact surveying and underground traverse surveying:In ground surveying, relative positional error of ground points reduces between original tunnel wellhead and received wellhead when using GPS. In contact surveying, the precision of pointing can be improved through increasing pointing times and take effective measures to reduce heavy hammer oscillating times strictly according to operating specification. In tunnel traverse surveying, measurement error is smaller than lmm generally using total station with ranging precision 1+1 ppm. The major influence factor is registration accuracy which has been effectively solved in our research by using manually centering rod.We can conclude from the above model that gyro azimuth error is the main error resource of tunnel breakthrough error affected by underground traverse after measuring gyro azimuth.2. The research of integration of GPS receiver and gyro has effectively solved the computation of meridian convergence angle that cannot be computed with urban metro independent coordinates. Develop automatic processing program has been tested correctly in computing gyro orient of experimental interval of Xi'an Metro Line No.1 and No.2.3. Develop YJTQ-1 total station manually centering and contacting device which effectively realizes contact between enforced centering platform and gyro. Not only from theoretical analysis but also from practical surveying results, we can both conclude that gyro enforced centering and contact device has advantages of stability and reusability over tripod. Thus gyro enforced centering and contact device can be applied in actual production.4. According to the principle of gyro azimuth measurement, we analyze known side of measuring instrument constant combining with factors affected metro breakthrough. The conclusion is that breakthrough error can decrease double when measuring instrument constant od known side near station.5. The study has realized visualization of control points. Control points mark is the prerequisite and important basis for securely surveying and could never be destroyed, otherwise, surveying can't carry out. Therefore, safely management of surveying mark is the prerequisite of normally surveying executing. This paper achieve the goal of real-time net visualized management of control point, which make surveyor better understand location and condition of control points to improve efficiency.6. The researched Metro Construction Surveying Networking Management Pattern is verified successfully in Xi'an Metro Line No.l construction and achieves phased results. The monitoring information system provides net adjustment, curve calculation and automatically gyroscope calculating tools for users to develop network management pattern suiting for metro surveying, and realizes network automotive managing in the form of modularization focused on the study of urban metro construction.7. Develop Secure Monitoring Forewarning Analyzing System of CS/BS Pattern. The unique characteristic of this system is meaningfully realizing map cursing changes of monitoring points, changing curves and map forewarning function through showcasing on line after locating each monitoring points on construction design drawings and realizing the combination of Web GIS and engineering practices provided for high-efficient working platform of urban metro security monitoring management. The system is a supplementary means for safely metro construction combining GIS and modern management system which realizes urban metro safely monitoring and analyze forewarning. The system can help metro constructors timely, accurately, directly and comprehensively find out different hidden dangers and accidents, receive various space information and attribute information through data collecting, managing, analyzing and map forewarning. The system can also provide necessary information basis for scientific decision-made by executors and safely construction.Highlights of innovation:1.Theoretically propose major factors affecting metro breakthrough surveying after measuring gyro azimuth of underground traverse.2. Effectively integrate GPS with gyro.3. Develop YJTQ-1 gyro enforced centering and contact device.4. Develop the geographical information system integrated GIS with engineering calculation security management by combing metro construction surveying calculation, surveying management and safety monitoring science.
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