Préconsolidation sousglaciaire des sédiments et signification paléogéographique du glaciaire de la vallé de l'Isére, la Tronche (Grenoble)
1. Préconsolidation sousglaciaire des sédiments et signification
paléogéographique du glaciaire de la vallée de l'Isére,
la Tronche (Grenoble)
Valenti Turu
3. 1
2 h
+
1
2
Tests
Bore-hole
Shear test
Voidratio
Pressure ( !)
1
Oedometric test
Sediment normally consolidated
Pressuremeter test =
Oedometric + Shear test
!
!'
"h*#*g
1 2
(Example)
876543210
0
50
100
150
200
250
P/V diagram
Stress (x 100 KPa)
Strain(Volumecm3)
( P o )
( P o ' )
Po
Po’
Pressurometer testing
4. Borehole data across the valley margin
SP107: Borehole coring and AMS
14C dating by G.Ménard
SP106: Pressurometer sounding
SP105: Pressurometer sounding
SP103: Pressurometer sounding
9. Geomorphological interptretation (classical)
H-ice – Hw ~ constant
small preconsolidation differences
H-ice – Hw <> constant
Hw
H-ice
> α(º)
high pervasive shearing zone
(glacier confluence)
Low pervasive
Shearing zone
High
pervasive
shearing
zone
Upper zoneLower zone
Vertical scale > Horizontal scale
10. Seeking out for plumbing paths
A) Glacier surpass a granular aquifer
B) Englacial and subglacial meltwaters
may be drained beneath the glacier
in the most efficient known form
(tunnels)
C) Flow paths under the central tunnel
D) Water and effective pressure in C
E) The same as D but further far from C
F) The shape of the effective pressure
beneath tunnels
11. Lateral moraines and lateral valleys are the main water inputs
Andorra modelling
Central tunnel is the sink of the groundwater flow. Equipotencitals goes from high to low values
Equipotentials and groundwater flowpaths
12. Consolidation of sediments near the subglacial tunnel
Andorra modelling
Equipotential refraction between permeabilities
Preconsolidation path
15. Preconsolidation values are in function of the palaeo-pore water pressures.
Gradation in preconsolidations should be exist in a stratified model (stratified permeability),
then preconsolidations order (fluence pressure) should be:
SP106 < SP105 < SP103
Paleaeorheology
17. Inverted chronology
Données nouvelles sur les formations argileuses du pied SE de la Chartreuse.
Conséquences paléogéographiques et néotectoniques
Gilles Ménard (2014) Lyon Q9 AFEQ