120 



TUNNELING 



the excavation. In other 

 places, where no disinte- 

 gration was apparent, 

 the rock was full of 

 seams and faults, and it 

 was necessary to support 

 the detached fragments 

 by timbering. In a few 

 places quite large cavi- 

 ties were encountered, 

 which were filled with 

 liquid mud. In one place 

 the inrush of liquid mud 

 was so sudden and the 

 stream so strong that 



\}Q meil barelv CSCaped 



* 



with their lives. 

 Excavation. The excavation was made by a heading 7 ft. 

 high and the full width of the section, and by a single bencli 

 excavation. In driving the heading two sets of holes were 



Double Timbering in Heavy Oround. 



FIG. GO. Transverse Section of Busk Tunnel Colorado 

 Midland R. R., Colorado. 



