JET GROUTING - A METHOD TO CONTROL GROUND SETTLEMENTS AND OVERBREAK FAILURES CAUSED BY TUNNELING IN WEAK ROCK CONDITIONS
This paper presents the gained experience from the use of jet grouting techniques for the control of ground settlements and overbreak failures, caused by tunneling operations in the weak rock environment of the Athens Metro project. Emphasis is given to features and limitations of jet grouting techniques, as these were evaluated with the aid of the results of performed fullscale tests. Moreover, the main characteristics of a complete ground treatment campaign is presented and the results in minimizing, during tunneling, both settlements and overhead failures are reported.
A study of concrete behavior over a large range of strain rates has been the focus of research conducted at the Joint Research Center-Ispra (JRC). The program was developed to produce new data concerning a few basic but debated subjects of industrial importance. In this paper, the influence of increasing aggregate size on the strain-rate tensile behavior of plain concrete is described. This study is a first step toward calibrating the constitutive law of concrete in the high-strain-rate field.