maximum safe pressure should be approached cautiously. A more conserv-
ative policy is to raise the pressure incrementally to approximately three-
fourths of the maximum allowable pressure, hold that pressure constant until
definite slowing of the injection rate is apparent, then raise slowly and by
increments to' the maximum. This reduces the spread of the grout, but more
important it usually permits the inspector to recognize lifting, if it takes
place, and to stop grouting at its inception. When lifting occurs it is often
accompanied by noticeable changes of pressure and grout consumption.
These changes last only a short time and may pass unnoticed by the inspector
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