The advance ratio is inherently related to the rest and
advance phases of a cement grout. When it is greater than
one, the grout is at rest, and when it is less than one, the
grout is advancing. When it is equal to one, it divides the
energy diagram into two subdomains which have the zero
flow path (ZFP) as a common border. Any grouting model
for rock fractures must take into account the ZFP.
An explicit consideration of the injection time together
with pressure control or flow rate control defines completely
and continuously the state of an advancing cement
grout.
The GIN target is inaccessible. The grout advance may
attain the reach or exceed it only if the grouting path in the
energy diagram crosses the edge hyperbola infringing the
GIN rule and principle.
The North American refusal criterion is reformulated
such that, from a desired grout advance to within a tolerated
margin is defined a necessary grouting pressure and a
corresponding flow rate limit that takes into consideration
the property of the grout and of the fracture.
Second-order effects are obtained, relaxing the basic
hypotheses that are used to obtain the analytic solution.
They are mostly felt at the beginning of the grouting process
and in the vicinity of the injection borehole.