SUMMARY:

The tunnelling changes the state /conditions of equilibrium, kinematic conditions etc./ of the surrounding soil in a finite region. This results in settlements of the surface. In urban area as it is the case of the Budapest metro too, the settlements must be limited for protecting the buildings against damages. One possibility for decreasing the surface settlements is to use an active /pressed against the soil/supporting system. The method applied at the Budapest metro is presented. The results of a FEM calculation show the beneficial effect of the active supporting system on the surface settlements.

ZUSAMMENFASSUNG:

Der Tunnelbau vera-ndert den Zustand /Gleichgewichtszustand, kinematischen Zustand usw./ der umhuellenden Erdmasse in einem endlichen Bereich. Dadurch entstehen Setzungen an der Oberflache. In Stadtgebieten, wie es auch der Fall bei der Metro in Budapest ist, die Setzungen muessen wegen dem Schutz der Gebaude beschrankt werden. Eine Möglichkeit fuer Herabminderung der Bodensetzungen ist die Verwendung eines aktiven Tunnel-Stuetz-Systems /gegen die Erde gepresst/. Die bei der Budapester Metro verwendete Methode wird vorgefuehrt.

RESUME:

La construction des tunnels modifie l''etat /l''etat d''equilibre, l''etat cinematique, etc./ du sol environnant dans une region finie. Ce qui fait le tassement de la surface du sol. Dans les regions urbaines ce qui est le cas aussi du metro de Budapest, les tassements doit etre limites pour proteger les batiments contre dommages. Une possibilite pour reduire les tassements c''est la construction avec un systeme de soutenement actif /presse contre le so~. Une methode appliquee aux Metro de Budapest est presentee.

INTRODUCTION

The tunnelling changes the state of the surrounding soil in a finite region. The constructing process results in a change in the initial conditions of equilibrium, in the initial kinematic conditions, that means the state of rest, and sometimes in the physical properties of the soil /e.g. dewatering, watering, grouting, etc./.

According to the construction method applied, to the soil conditions land to many other factors/, the field of displacements may be quite different, but may be artificially influenced.

In urban areas it is very important to know the permissible settlements or deflection of the surface for avoiding damages of the buildings standing over the area of tunnelling.

To protect the buildings against damages due to the settlements, there are two general ways. Passive way. - Protection is carried out on the surface. In this case buildings are reinforced by different construction methods /e.g. underpinning, tieing the elements or cutting in blocks etc./ for making them capable to bear the effects of settlements. Active way. - Protection is carried out at the deep level by choosing the appropriate construction method. One of these is the active supporting system /temporary supports supporting system /temporary supports or final structure are pressed against the soil/rock surface/ suited to the tunnelling method. There are at least two possibilities here: In the case of shield tunnelling, the lining is pressed against the surrounding soil/e.g. it was used for running tunnels at the London Underground, Leningrad and Moscow Metros/ In the case of constructing underground cavities /e.g. metro stations etc./ by the mining method, active temporary supporting systems are used /e.g. active temporary supporting system was used at construction of parts of a metro station in Paris/.

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