Analysis of the Importance of the Filling Material Characteristics Injected Around the Precast Concrete Lining in the Microtunnelling Technology

Abstract Microtunnelling is an excavation technique capable of positioning underground pipes with considerable advantages from the point view environment, safety, construction times and also total costs, when lengths are significant. The technology used now reliable suitable for use in different types soils rocks without particular problems. installation concrete lining micro-tunnel takes place behind machine starting a thrust shaft. A filling material must be injected between outer surface tunnel wall. This plays very important role, because it conditions overall stiffness support system and, therefore, influences radial load applied by ground to system. Therefore, necessary take into account presence order correctly size micro-tunnel. paper illustrates new procedure analyzing behavior system, based on widely tested analytical calculation methods. was real case, underway Northern Italy. results obtained were then compared those numerical modeling, which made possible simulate detail. From comparison note how leads stress states similar (slightly higher) modeling; first, can effectively preliminary stages design micro-tunnels obtain useful information characteristics systems adopted ensure stability.