Development of a Mobile Laser Measurement System for Subway Tunnel Deformation Detection
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In recent years, mobile laser measurement systems have markedly enhanced the capabilities of deformation detection and defect identification within metro tunnels, attributed to their superior efficiency, precision, and versatility. Nevertheless, challenges persist, including substantial equipment costs, inadequate after-sales support, technological barriers, and limitations in customization. This paper develops a mobile laser measurement system that has been specifically developed for the purpose of detecting deformation in metro tunnels. The system integrates multiple modules, comprising a rail inspection vehicle, a three-dimensional laser scanner, an odometer, and an inclinometer, to facilitate multi-sensor temporal synchronization. By leveraging data from the inclinometer and odometer, the system performs point cloud coordinate corrections and three-dimensional linear reconstructions. Experiments conducted on the Xuzhou Metro validate the reliability and stability of the system, demonstrating its capability to meet routine deformation detection requirements. To improve deformation detection utilizing point cloud data, a pre-processing algorithm has been proposed, which incorporates point cloud denoising, centerline calculation, roadbed removal, and relative positioning based on mileage. Disturbed points are systematically identified and eliminated, while the convergence of tunnel sections and inter-ring misalignment are evaluated through ellipse fitting. Furthermore, to address encroachments upon tunnel locomotive limits, encroachment points and associated information are identified using the ray method. In conclusion, the proposed mobile laser measurement system offers an efficient and reliable solution for metro tunnel deformation detection, with significant potential for broader applications and future advancements.Keywords:
Inclinometer
Odometer
Mobile mapping
Deformation monitoring
Laser Scanning
Positioning technology
Locata Corporation's positioning technology "Locata" is a terrestrial-based RF-ranging technology that provides high accuracy position solutions using a network (LocataNet) of time synchronised pseudolite-like transceivers (LocataLites). This technology provides centimetre level accurate position solutions for static positioning using carrier phase measurement data which provides an advantage over other technology for monitoring structural movement in many applications. The Locata network can be deployed in such a configuration around a structure that optimal network geometry could be ensured despite site constraints. This paper describes the first deformation trial using Locata technology carried out at Tumut Pond Dam, in the state of New South Wales, Australia. This trial was run for 22 hours and yielded millimetre-level precision for horizontal positions, and centimetre-level vertical precision for all observed epochs. The accuracy of the coordinate solutions was at the few millimetre level with standard deviations of 2.5 mm, 2.1 mm and 18 mm for the east, north and height components respectively. The position solutions were generated by an iterative least squares estimation process of Locata carrier phase observations per epoch. Then mean of sixty seconds coordinate solutions was used as input for a Kalman filter. Standard deformation detection methods were applied. No significant displacement was observed during this trial.
Deformation monitoring
Positioning technology
Position (finance)
Ambiguity Resolution
Ranging
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In special area such as vehicle mobile mapping system,post high accuracy of position and attitude is required.Contraposed to these characteristics of the integrated system,a new method which using the position information of DGPS to calibrate misalignment angle of static initial self-alignment is introduced.The practical application results illustrate the efficiency of the new method,which can be accorded with the demand of engineering.
Odometer
Position (finance)
Mobile mapping
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One of the most intricate branches of metrology involves the monitoring of displacements and deformations of natural and anthropogenic structures under environmental forces, such as tidal or tectonic phenomena, or ground water level changes. Technological progress has changed the measurement process, and steadily increasing accuracy requirements have led to the continued development of new measuring instruments. The adoption of an appropriate measurement strategy, with proper instruments suited for the characteristics of the observed structure and its environmental conditions, is of high priority in the planning of deformation monitoring processes. This paper describes the use of precise digital inclination sensors in continuous monitoring of structural deformations. The topic is treated from two viewpoints: (i) evaluation of the performance of inclination sensors by comparing them to static and continuous GPS observations in deformation monitoring and (ii) providing a strategy for analyzing the structural deformations. The movements of two case study objects, a tall building and a geodetic monument in Istanbul, were separately monitored using dual-axes micro-radian precision inclination sensors (inclinometers) and GPS. The time series of continuous deformation observations were analyzed using the Least Squares Spectral Analysis Technique (LSSA). Overall, the inclinometers showed good performance for continuous monitoring of structural displacements, even at the sub-millimeter level. Static GPS observations remained insufficient for resolving the deformations to the sub-centimeter level due to the errors that affect GPS signals. With the accuracy advantage of inclination sensors, their use with GPS provides more detailed investigation of deformation phenomena. Using inclinometers and GPS is helpful to be able to identify the components of structural responses to the natural forces as static, quasi-static, or resonant.
Inclinometer
Deformation monitoring
Continuous monitoring
Structural Health Monitoring
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The geological subsidence of substations is sudden and complex, and its rapid and accurate monitoring and early warning is of great significance to the safe and stable operation of the power system. This paper presents a method for monitoring the geological subsidence of substations with high-precision Beidou positioning technology. On the one hand, it can optimize the PTK technology, and on the other hand, it can comprehensively process the data of the reference station and monitoring station and use the reference station as a reference to grasp and understand. The deformation of monitoring points ensures the accuracy of monitoring. In this paper, the output of pseudorange, carrier phase and other information of high-precision Beidou satellites is used to meet the requirements of positioning solution. Secondly, the principle of vertical and horizontal displacement monitoring of geology substations of high-precision Beidou satellite receivers is given. Finally, the settlement is given. The selection principle of monitoring base station, monitoring station and communication network. The high-precision Beidou positioning monitoring method proposed in this paper can quickly, real-timely, and accurately monitor and warn the geological subsidence of substations, changing the previous situation of manual monitoring of geological subsidence.
Deformation monitoring
Positioning technology
Master station
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The fixed inclinometer is an effective tool in monitoring the internal status of tailing dam,with the character of high sensitivity,high-precision and high stability,and it can monitor the internal displacement,deformation velocity and movement direction of tailing dam in real time.The GK-6150 clinometer is described and the application of real time monitoring of a tailing dam is introduced.It is shown that the clinometers not only provide effective information on analyzing the structure,evaluating the stability and deformation trend,but also play a very good effect on dam monitoring.
Inclinometer
Deformation monitoring
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To meet the need for calculating road slop and relative altitude changes while moving in vehicle navigation system,this paper proposes a new estimation algorithm for slope and relative altitude based on odometer and single-axis accelerometer.This algorithm overcomes the drawback of traditional inclinometer which cannot function when accelerating,thus it is able to measure road slop in any state of movement.The method also designs a simple fusion algorithm of inclinometer measurement and strategy on slope driving discrimination on this basis.It enables fast,precise measurement and judgment when driving on a slope,therefore provides strong support for road auto-judgment of vehicle navigation system during complex circumstances.
Inclinometer
Odometer
Sensor Fusion
Navigation System
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Innovation of the mining deformation monitoring technology has been aroused with the development of GNSS technology. This paper probe into the feature of mine Continuously Operating Reference Station (CORS) and precise height difference model was constructed in Yanzhou and inner Mongolia to practise the technology. Based on the technology of mining CORS, we proposed the mining 3D deformation monitoring technology of large area. Based on the technology of RTK, we proposed the mining subsidence monitoring technology of small area. Based on the construction of the model of height difference, GNSS-RTK technology was proposed to be used in subsidence monitoring. This paper provides specific ways to the modernization GNSS monitoring technology in mining deformation.
Deformation monitoring
Positioning technology
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This paper presents the current internal defects positioning technology of pipeline, and deeply analyzes the characteristics of the main positioning methods, error causing mechanism and accumulative characteristics, and proposes a new combined positioning procedure, which applies INS (inertial navigation system) assisted by ground markers /weld /odometer to achieve the exact position of internal defects of oil and gas pipeline. INS is the core of positioning as a non-contact measurement. Its positioning manner is not affected by the internal environment of the pipeline and the error production and accumulation characteristics can be estimated; applying ground markers and weld signal, INS errors could be limited at a small range. This paper also develops a mathematical model of INS, establishes the INS/odometer navigation algorithms in accordance with positioning characteristics of the pipeline internal defects, and makes quantitative analysis on the algorithm errors of INS and the combination, which makes a useful exploration so as to reduce positioning errors and develops high accuracy of the positioning scheme.
Odometer
Positioning technology
Precise Point Positioning
Position (finance)
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This chapter describes the observables and the operation principles of various geotechnical instrumentations for deformation monitoring. It discusses the advantages and disadvantages (or limitations) of various geotechnical instrumentations for deformation monitoring. The geotechnical and structural techniques of deformation monitoring mainly focus on monitoring and analysis of hydroelectric dams. The chapter discusses the various applications of geotechnical monitoring techniques, using extensometers, four-pin gauges, joint meters, plumblines, inclinometers, tiltmeters, fiber-optic sensors (FOS), and micro-electro-mechanical system (MEMS) sensors. In Geomatics, the design of monitoring schemes is usually done based on the criteria such as precision, reliability, and overall cost of measurements. The chapter identifies the differences between geotechnical and geodetic deformation monitoring schemes. It explores accuracy specifications for various geotechnical instrumentations with regard to deformation monitoring. The chapter explains how geotechnical monitoring techniques complement geodetic monitoring techniques.
Inclinometer
Extensometer
Tiltmeter
Deformation monitoring
Geotechnical investigation
Vibrating wire
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The significance of dam deformation monitoring,not only on new projects but also the automation transformation of old projects,was emphasized here.The deficiency of conventional monitoring points arrangement on dam top for horizontal deformation was pointed out which also exert bad influence on data analysis.By analysis on existing deformation monitoring instruments,it was found that they all had serviceable range and condition that when instrument choosing,actual need should be considered.Referring to the inclinometer and similar instruments for indirect measurement methods,possible precision and change range of the object should be forecasted to meet the require of measurement precision.This paper,at last,stressed the management and maintenance of the automatic monitoring system.Only in this way,data reliability and system operation stability can be guaranteed.
Inclinometer
Deformation monitoring
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