The effect of tunnelling on repeated precise levelling measurements for vertical deformation control of the Metro4 project

Cs. Égető, L. Földváry, T. Huszák
2013 Journal of Geodetic Science  
The effect of the construction of the 4th subway line of Budapest (Metro4) on the potential surfaces of the gravity field has been simulated, using the prism modelling technique. In the study mass loss due to the excavation of the two tunnels and of the stations has been considered. Mass variations deform the level surfaces; as so, the vertical reference surface of the levelling measurements is changing by time. In this study, the effect of the mass loss on levelling measurements was determined
more » ... ents was determined at a level 1 m above the ground, roughly simulating common instrument heights. Subsequently, the effect of the actual deformations of the surface on the levelling measurements has also been determined. According to the results, under certain arrangements of the levelling line with respect to the position of the excavations, the error due to the change of the vertical reference is in the 1 µm order of magnitude, thus negligible. Keywords: Budapest Metro4 project • levelling • prism modelling • temporal variations of gravity where δh is the actual surface deformation, δH is the change in orthometric height, and δNis the change of the geoid undulation due to the mass variation. (Temporal variation between two Brought to you by | Kando Muszaki Foiskola
doi:10.2478/jogs-2013-0015 fatcat:6m7xtas5x5f6tj77o5bvi2tgru