Deflection of the Vertical Components from GPS and Precise Leveling Measurements in Hong Kong

Tse, Cheuk-kin; İ̇z, H. Bâki

doi:10.1061/(asce)0733-9453(2006)132:3(97)

Cited by 14 publications

(9 citation statements)

References 2 publications

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“…The combination of GNSS (global navigation satellite system) measurements and spirit leveling in local geodetic networks yields vertical deflection data independent of star observations (e.g. Soler et al 1989, Tse andIz 2006). Gravity measurements are commonly used for the computation of gravimetric vertical deflections applying the Vening-Meinesz formula (e.g.…”

Section: Introductionmentioning

confidence: 99%

Modern Determination of Vertical Deflections Using Digital Zenith Cameras

et al. 2010

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At the beginning of the 21 st century, a significant technological change took place in geodetic astronomy. In Zurich and Hannover, digital zenith camera systems were developed based on digital imaging sensors (CCD) that strongly improved the degree of automation, efficiency and accuracy of the observation of the direction of the plumb line and its vertical deflection. This paper describes the instrumental design of the new digital zenith camera systems and gives an overview of the data processing with focus on the models used for astrometric data reduction and tilt correction. Results of frequently repeated observations of vertical deflections and comparison measurements show an accuracy of vertical deflection measurements of better than 0.1 arc seconds. Application examples for vertical deflection data from zenith camera observations, such as the high-precision local gravity field determination in engineering projects and gravity field validation are summarized.

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Section: Introductionmentioning

confidence: 99%

Modern Determination of Vertical Deflections Using Digital Zenith Cameras

et al. 2010

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“…The basic principle of astronomical levelling gives us a definite mathematical relationship between geoid undulations and vertical deflection (Vӧlgyesi, 2005;Tse andBâki Iz, 2006, Ceylan, 2009). According to the notations of Figure 4 we get: So from determined geodetic azimuth and geodesic distance from equations (18) and (19), ∆N12 can be computed.…”

Section: Geoid Undulation (∆N)mentioning

confidence: 99%

The Role of Astro-Geodetic in Precise Guidance of Long Tunnels

Mirghasempour

Jafari

2015

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:One of prime aspects of surveying projects is guidance of paths of a long tunnel from different directions and finally ending all paths in a specific place. This kind of underground surveying, because of particular condition, has some different points in relation to the ground surveying, including Improper geometry in underground transverse, low precise measurement in direction and length due to condition such as refraction, distinct gravity between underground point and corresponding point on the ground (both value and direction of gravity) and etc. To solve this problems, astro-geodetic that is part of geodesy science, can help surveying engineers. In this article, the role of astronomy is defined in two subjects: 1-Azimuth determination of directions from entrance and exit nets of tunnel and also calibration of gyro-theodolite to use them in Underground transvers: By astronomical methods, azimuth of directions can be determine with an accuracy of 0.5 arcsecond, whereas, nowadays, no gyroscope can measure the azimuth in this accuracy; For instance, accuracy of the most precise gyroscope (Gyromat 5000) is 1.2 cm over a distance of one kilometre (2.4 arcsecond). Furthermore, the calibration methods that will be mention in this article, have significance effects on underground transverse. 2-Height relation between entrance point and exit point is problematic and time consuming; For example, in a 3 km long tunnel ( in Arak-Khoram Abad freeway), to relate entrance point to exit point, it is necessary to perform levelling about 90 km. Other example of this boring and time consuming levelling is in Kerman tunnel. This tunnel is 36 km length, but to transfer the entrance point height to exit point, 150 km levelling is needed. According to this paper, The solution for this difficulty is application of astro-geodetic and determination of vertical deflection by digital zenith camera system TZK2-D. These two elements make possible to define geoid profile in terms of tunnel azimuth in entrance and exit of tunnel; So by doing this, surveying engineers are able to transfer entrance point height to exit point of tunnels in easiest way.

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“…Therefore, the determination of the deflections of the vertical is very important work. Traditionally, the deflection of vertical components are determined from astro-geodesy [21][22][23], gravimetry [24,25], GNSS/leveling [26,27], etc. from which it is easier to calculate the deflections of the vertical with an Earth gravity field model and a geoid model.…”

Section: Introductionmentioning

confidence: 99%

GNSS-Based Verticality Monitoring of Super-Tall Buildings

Zhang

et al. 2018

Applied Sciences

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In the construction of super-tall buildings, it is rather important to control the verticality. In general, a laser plummet is used to transmit coordinates of reference points from the ground layer-by-layer, which can effectively control the verticality of super-tall buildings. However, the errors in transmission will accumulate with increasing height and motion of the buildings in construction. This paper presents a global navigation satellite system (GNSS)-based method to check the results of laser plumbing. The method consists of four steps: (1) Computing the coordinate time series of monitoring points by adjusting the GNSS monitoring network observations at each epoch; (2) Analyzing the horizontal motion of super-tall buildings and its effect on vertical reference transmission; (3) Calculating the deflections of the vertical at the monitoring point using an Earth gravity field model and a geoid model. With deflections of the vertical, the static GNSS-measured coordinates are aligned to the same datum as used by the laser plummet; and (4) Finally, validating/checking the result of laser plumbing by comparing it with static GNSS results corrected by deflections of the vertical. A case study of a 438-m high building is tested in Guangzhou, China. The result demonstrates that the gross errors of baseline vectors can be eliminated effectively by GNSS network adjustment of the first step. The two-dimensional displacements can be measured at millimeter-level accuracy; the difference between the coordinates of the static GNSS measurement and laser plumbing is less than ±2.0 cm after correction with the deflections of the vertical, which meets the design requirement of ±3.0 cm according to the Technical Specification for Concrete Structures of Tall Buildings in China.

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Deflection of the Vertical Components from GPS and Precise Leveling Measurements in Hong Kong

Cited by 14 publications

References 2 publications

Modern Determination of Vertical Deflections Using Digital Zenith Cameras

Modern Determination of Vertical Deflections Using Digital Zenith Cameras

The Role of Astro-Geodetic in Precise Guidance of Long Tunnels

GNSS-Based Verticality Monitoring of Super-Tall Buildings

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