TI:::A HKKOI s <;I;I;M> MKTH'I> 1G7 



CHAPTER XVI. 



SPECIAL TREACHEROUS GROUND METHOD; 

 ITALIAN METHOD; QUICKSAND TUN- 

 NELING; PILOT METHOD. 



ITALIAN METHOD. 



THE Italian method of tunneling was first employed in con- 

 structing the Cristina tunnel on the Foggia & Benevento K.K. 

 in Italy. This tunnel penetrated a laminated clay of the most 

 treacherous character, and after various other soft-ground 

 methods of tunneling had been tried and had failed, Mr. Procke, 

 the engineer, devised and used successfully the method which 

 is now known as the Italian or C'ristiiui method. The Italian 

 method is essentially a treacherous soil method. It consists in 

 excavating the bottom half of the section by means of several 

 successive drifts, and building the invert and side walls; the 

 space is then refilled and the upper half of the section is exca- 

 vated, and the remainder of the side walls and the roof an b 

 are built ; finally, the earth filling in the lower half of the 

 sei-tion is re-excavated and the tunnel completed. The method 

 is an expensive one, but it has proved remarkably successful in 

 treacherous soils such as those of the Apennine Mountains, 

 in which some of the most notable Italian tunnels are located. 

 1 1 ii, ini'..ver, a single-track tunnel method, since any soil 

 which is so treacherous as to warrant its use is too treacherous 

 to permit an opening to be excavated of sufficient size for a 

 double-track railway, except by the us.- of shields. 



Excavation. The plan of excavation in the Italian method 

 is shown by the diagram Fig. 92. Work is begun by driving 



