A053
ATLANTIC TGV - MONTPARNASSE STATIONMONTPARNASSE STATION PROJECT
- COVER SLAB - PARIS - FRANCE
Grouting
Filling of underground galleries and consolidation ofcollapsed
rock prior to constructing deep, heavy loadbearing foundations
CLIENT: S.N.C.F. (FRENCH RAILWAYS)CONSULTING ENGINEERS:
SIMECSOLINSPECTION AUTHORITY: SOCOTECMAIN CONTRACTOR: J.V. FOR THE
PARIS-MONTPARNASSE
COVER SLABCONSULTANT: TERRASOLSPECIALIST CONTRACTOR:
BACHYDURATION OF WORKS: AUGUST 1987 TO NOVEMBER 1989
WORKS QUANTITIES
71,500 linear meters of drilling 31,000 m3 of mortar injected
16,200 m3 of grout injected
Geological section
60
50
40
30
20Marl
Coarse limestone
Quarry zone
Marls andlimestone beds
Marls and limestone beds
Beauchamp sand
Fill and old alluvium
EM = Pressiometer modulus (MPa)E = Young modulus (MPa)
EM = 7 to 15
EM = 25
EM = 50
E = 1,000 to 2,000
E = 40 to 100
Geologicalandhistorical backgroundThe Montparnasse
StationProject in Paris consisted of buil-
ding a cover slab over the existing
railway tracks to support a future
building complex.
It was decided to carry the loads
involved in the project on heavy
load capacity barrettes socketed
into the coarse limestone at about
25 m depth.
This hard limestone bed had been
mined in the past in its upper
section for building stone, leaving
some open and some partially
filled galleries. Locally, collapse
of the gallery roofs had caused
bell-shaped subsidence features in
the overlying marls and gravel
soils.
The const ruct ion of the
foundations thus necessitated
the complete infilling of the
galleries to avoid mud losses
during the excavation of the
barrettes. The upper slumped soils
also had to be compacted and
consolidated by grouting from
the existing working platform
level, to mobilise lateral positive
friction along the surfaces of the
barrettes.
A053
0
62.5
125
187.5
250
312.5
375
437.5
500 0 100 200 0 100 200
1
10
20
26
-1-1-1
-10-10-10
-20-20-20
-26-26-26
TCH 100 DRILLING RIG
Embank-ment
Marls&
Limestone
M & Pdcompressed
Marls&
Limestone
Limestone
LimestoneVoid
DRILLING SPEED(M/H)
LITHOLOGY
THRUSTPO (bar)
GROUTPI (bar)
0
62.5
125
187.5
250
312.5
375
437.5
500 0 100 200 0 100 200
DRILLING SPEED(M/H)
LITHOLOGY
1
10
20
26
-1-1-1
-10-10-10
-20-20-20
-26-26-26
B.E. DRILLING RIG
Embank-ment
Marls&
Limestone
Void
Limestone
THRUSTPO (bar)
GROUTPI (bar)
Primary grout holes(mortar)Secondary grout holes(grout)
Grout holes for mortar+ groutSecondary grout holes
(grout)grouted down to 1 m below thefoot of the barrettes
A B C
D
A) Mortar filling of the gallery voidB) Additional grouted
slurryC) Soil strengthening in the vicinity of the barrettesD)
Possible strengthening if decompressed zone
Gallery
Barre
tte
6.00
6.00
6.00 1.00
1.00
1.00
3.00
3.00
3.001.001.001.00
1.001.001.00
Bentonite Mud storage CementMud mixingplant
Slurrypreparation plant
Moritzmixer
LoaderFine sand Groutpump
Groutpump
FillMarls &
limestone
Quarryzone
Coarse limestone
FillingStrengthening
Injection borehole equipmentRecording of the drilling
parameters
Mud preparation plant and grouting process
Injection treatment grid around a group ofbarrettes
Surveying the voids and thesubsidenceIn order to be able to
modify thetreatment required on a hole by holebasis, bearing in
mind the random distri-bution of the voids and loosened ground,a
systematic survey was carried out bydrilling a pattern of holes
with digitalrecording of the drilling parameters.
Filling and Quality ControlOpen cavities were filled with
mortarwhile loosened ground was pressuregrouted with traditional
bentonite cementgrout adapted to the ground conditionsanticipated
locally. For each processcriteria were established based on
maxi-mum pressures and precisely calculatedgrout quantities related
to the digitaldrilling parameter data for that hole.The grouts and
mortars were continuously
monitored for consistency with thedesigned mixes in a complete
lyautomated batching and mixing plant.This had a capacity of 40
m3/h for groutsand 25 m3/h for mortar. The actual volu-mes injected
were measured at theindividual pumps by electromagneticflow
meters.
Rate of Production for Stage 1- 30 no to 40no drill holes per
day with4 no rigs working double shift,- 200 to 300 m3 of mortar
and 100 to500 m3 of grout injected per day with6 no mortar pumps
and 12 no grout pumpsworking double shift.
Grouting chronology- preliminary infil l ing of the
opengalleries by gravity injection of mortar(5 m x 5 m grid),
- pressure grouting at the crown of thef i l led gal lery zones
to access anyremaining voids and to compensate forshrinkage on
setting of the mortar,- consolidation of the overlying
loosenedrocks and soils by injection of bentonite-cement grout,-
grouting of any limestone fissures belowthe toes of the
barrettes.These latter operations were carried outby grouting under
pressure through"tubes--manchettes" installed in a newseries of
holes on a 5 m x 5 m grid acrossthe site.Peripheral barriers were
installed aroundvarious zones in the site through a seriesof
"tubes-a-manchettes". Both mortar andgrout were injected in the
formation ofthese barriers.
