Show SHAFT SINKING BY CEMENT INJECTION cement age 1 new york A paper on shaft sinking against water in fissured ground by cement injection by A L reported in part in the stone trades journal london described a process that is now replacing to some extent the freezing process for the sinking of shafts in water bearing ground it was developed in the chalky formation of the pas de calais co alfield but i is equally suited for any water bearing rocks although not for soft run ning ground such as quicksand the author said that the principle was that a number of boreholes bore holes of suitable dimensions were sunk at equal intervals in the form of a ring surrounding the proposed site of a shaft cement and water injected through these boreholes bore holes by means 0 or force pump found their way into all the cavities and crevices of the ground surrounding each hole in which the cement set AS the cement from one hole penetrated the rocks surrounding it that coming from the adjoining hole was encountered and a cement watertight wall was formed round the proposed site of the shaft in this way it was possible to get rid of the water troubles that occurred in the process of sinking the equipment for the process was small and inexpensive as compared with that required for making an lee ice wall by the process besides which when once the cement had set the work on the plant was finished whilst with the method the machinery had to be kept at work until the shaft had been sunk and lined a considerable extra being thus incurred As a result sult of these savings the cost of sinkin sinking 1 by cement injection was only about one third that of the process the practical advantage was that water was almost completely shut out and a masonry lining if necessary was made more secure though the solid wall of concrete made the he lining almost superfluous the danger to shaft sinker was greatly lessened as they had not to cope with continual water troubles when sinking and in iii the event of repairs to shaft lining being necessary later the existence of the permanent cement wall practically shut out all water from the shaft |