INTERACTIVE GEOTECHNICAL DESIGN OF BRIDGE FOUNDATIONS

Abstract: The paper presents the role and the importance of interactive approach to geotechnical designing of bridge foundations. Interactive geotechnical design means that the project design of foundations, and maybe even of the bridge itself, based on investigation works, should be corrected or changed while taking into consideration the results of stress and strain measurements of the main foundation and of the bridge during the construction. Interactive geotechnical design is shown on the example of the "Krapinčica " viaduct, which was constructed as part of Zagreb-Macelj highway project. Pile foundations were designed first. After the construction of piles, bearing capacity testing was carried out on the piles, which turned out to be unexpectedly low. In order to prevent the ground from breaking and to prevent excessive viaduct deformations, ground improvement method Jet Grouting was used to improve stiffness and bearing capacity of the pile ground. Furthermore, sliding micrometers were inserted into the piles and they enabled the monitoring of vertical strain of the piles and of the ground. Measurements were conducted with the sliding micrometer in several stages of the viaduct construction. It was established that the state of viaduct deformations had been within project assumptions and no additional methods for ground improvement or for the basic viaduct construction were necessary. Interactive geotechnical design shown in this paper gives to Foundation Designer and to Bridge Designer the quickest, the safest and the most rational way of intervening into the existing design. 1