671017.pdf

A com parison of water perm eability aer grouting

Wat

er

perm eabi

lit

y

(Lu)

2. 5

2

1. 5

1

0. 5

0

Grouting stage

0 2 4 6 8 10 12

Simulated value

Design im perm eable Actual value

(a)

A com parison of wave velocity aer grouting

Wave

vel

oci

ty

(m/

s)

7000

6000

5000

4000

3000

2000

1000

0

Grouting stage

024681012

Simulated value

Actual value

(b)

Figure 4: Comparison of the grouting effect after grouting with 1 m as the design diffusion radius.

0

00.511.522.533.544. 5

Distance from central of hole (m)

Dept

h

of

hol

e (

m)

Diusion line of 3 Lu

Diusion line of 1 Lu

Hole location

− 10

− 20

− 30

− 40

− 50

− 60

Figure 5: Distribution of the water permeability at different dis-
tances.

As for the simulation results with 95% confidence, the
grouted stages whose diffusion distance away from the
drilling center was the smallest and also satisfied the design
standard were Stage 8 (40.5–45.5 m) and Stage 9. The hole
distance in these two stages was 2.2 m, more than the design
value, 2 m. Therefore, if the simulation value with that
confidence was adopted, the hole spacing could be optimized
to2.2m,anincreaseof0.2moverthedesignvalue,directly
savingupto10%oftheprojectamount.
As for the simulation results with 80% confidence, the
grouted stages whose diffusion distance away from the
drilling center was the smallest and also satisfied the design
standard were Stage 6 (30.5–35.5 m), Stage 8, and Stage 9. The
hole spacing in these three stages was 2.4 m. It should not be
applied directly due to its 80% confidence.

0

0 0.511.522. 53 3. 5

Distance from central of hole (m)

Dept

h

of

hol

e

(m)

Diusion line of 1 Lu on con dence space with 100%

Diusion line of 1 Lu on con dence space with 95%

Diusion line of 1 Lu on con dence space with 90%

Diusion line of 1 Lu on con dence space with 80%

Diusion line of 1 Lu on the mean

Hole location

− 10

− 20

− 30

− 40

− 50

− 60

Figure 6: Probability of the distance in each grouting stage with

permeability rate less than 1 Lu.

5. Conclusion

Basedonthemutualcouplingofthediffusionprocessof

cement grouting in the fissures and the deformation of

rock mass under grouting pressure, the diffusion and filling

process for cement grouting in V-diabase grouting test in the

Dagang Mountain Hydropower Station was simulated using

the finite element method, considering the time variability

of rheological parameters of cement grout, the changes in

thefissureopening,andtheprecipitationlawofthecement

particles. Distribution of the permeability rate in grouted

rock mass was analyzed, and the reliability and optimization