Study On The Method Of Monitoring And Data Processing For Metro Tunnel Deformation

Due to the urbanization and large scale development, kinds of cities are considering underground traffic as an efficient means to solve the problem of worsening ground traffic. On one hand, construction of rail systems has to face the issue of transposition or transfer, newly built lines have to pass through the old ones. On the other hand, metros give a boost to the economy along its path, thus the foundation pits around the section is increasing. Those underground projects break the force balance of the existing tunnels, deformation resulted from this will cost significantly if not handled properly. In the cities like Beijing, Tianjing with a history of underground railway operation more than50years, overall monitoring of the whole line is necessary for a better comprehensive understanding. Therefore, the study for long-term, real-time monitoring solution of underground railway tunnels, and data processing and analysis method is crucial to ensure the safe operation of underground traffic systems.At present, the tunnel monitoring is mainly about segment deformation under expected stress change, and long-term, overall monitoring has never been tapped:The monitoring method now in use bases its analysis of overall deformation on the changes of individual points, so the overall deformation of tunnel section cannot be reflected accurately. Additionally, the reliable base points cannot be guaranteed in large-scale or curve areas. Therefore, the dissertation presents a subway monitoring and management system featuring low-cost and high-efficiency, targeting at long-term overall monitoring of railway tunnel, as well as major monitoring locally. The study focuses on the method of subway monitoring, the establishment of unified coordinate system, the extraction of section deformation information, the analysis and predicament of deformation data. The main contents are as follows.1. On the foundation of the proven contents and methods of subway deformation monitoring, the dissertation introduces wireless sensor network, presenting a feasible program on wireless sensor network applying in long-term monitoring of subway relative deformation. Combining the program with automatic local deformation monitoring and periodic datum network monitoring, a low-cost, high-efficient subway monitoring and management system hence is established.2. By combining relative deformation and overall tunnel cross section deformation, a method of unifying tunnel-based coordinate datum is presented. It studies the netting and observation methods of the free station marginal intersection net which is used in tunnels; relatively, structure the plane net and trigonometric height networks; has analyzed preprocessing, net adjustment and results accuracy of the benchmark network graphic data. It proposes a structuring standard of the vertical control network and studies its data processing. The afore said method is utilized in processing the monitoring data of an Intersection Net established during the constructing period of a certain high speed railway. The precision of planar point coordinate and consecutive point coordinate thusly obtained is in accordance with the result of laboratory analysis, and it can meet with subway deformation monitoring. In the meantime, the result of adjusted height obtained by the above method is compared with that of geometrical leveling to verify the precision of trigonometric height networks.3. With regard to the error of control points and the correlation between each point, the precision of free station by unified datum network is analyzed and simulated. The dissertation introduces the commonly used methods of stability analysis of datum network, and studies the method based on datum coordinate change for free station.4. The approach of describing section deformation feature by scanning the cross section, specifically B-spline curve simulation, is proposed to replace the traditional method, by which the section deformation is simply analyzed by individual points’ deformation. Based on study of different methods for knot placement of uneven B-spline curves, a modified approach to resolve knot vector using doiminat points and new algorithm to distinguish section and out-of-section information is presented.5. The Hausdorff distance algorithm is selected to be the proper distance measurement method of characterizing tunnel cross section deformation based on study and analysis of different methods of distance measuring between free curves. It is described in detail and then applied in deformation data of a selected cross section.6. The comparison and interconversion of different dynamic processing methods that are currently used is presented. The construction simulation analysis function of Midas is used to analyze the data obtained during excavation of foundation trench. The result is then used as control information for data processing. Finally, the Kalman filtering model with regard to construction analysis result is proposed.