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Z_SOIL.PC DAY 2008 Case Study Stability of an earthdam Stéphane Commend – Françoise Geiser GeoMod consulting engineers www.geomod.ch.

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Presentation on theme: "Z_SOIL.PC DAY 2008 Case Study Stability of an earthdam Stéphane Commend – Françoise Geiser GeoMod consulting engineers www.geomod.ch."— Presentation transcript:

1 Z_SOIL.PC DAY 2008 Case Study Stability of an earthdam Stéphane Commend – Françoise Geiser GeoMod consulting engineers

2 Z_SOIL.PC DAY 2008 Summary Settlement analysis of the existing earthdam Global stability analysis Stability analysis of the earthdam (= local) Simplified seismic analysis Work in progress

3 Z_SOIL.PC DAY 2008 Summary Settlement analysis of the existing earthdam Global stability analysis Stability analysis of the earthdam (= local) Simplified seismic analysis Work in progress

4 M100 – SC – March 2008 Dam and material deposit overview schematic position of the future material deposit existing earthdam 2D cut

5 Z_SOIL.PC DAY 2008

6 Existing earthdam

7 Z_SOIL.PC DAY 2008 Access road

8 Z_SOIL.PC DAY 2008 Material deposit. Step 1

9 Z_SOIL.PC DAY 2008 Material deposit. Step 2 (provisory)

10 Z_SOIL.PC DAY 2008 Material deposit (final configuration) V calc = 1’643’000 m 3

11 Z_SOIL.PC DAY 2008 Existing earthdam Material deposit (final configuration) Water basin

12 M100 – SC – March 2008 future material deposit Dam and material deposit 2D cut about 500 m 25 m earthdam

13 Z_SOIL.PC DAY 2008 Pore pressure, with cracked asphalt (K = 1e-4 m/s) Asphalt

14 Z_SOIL.PC DAY 2008 Absolute displacements, 2D model T = 6: maximal displacement, with provisory deposit Settlement = 3.0 cm

15 Z_SOIL.PC DAY 2008 Deformed mesh (x 20), 2D model T = 6: maximal displacement, with provisory deposit Initial position

16 Z_SOIL.PC DAY 2008 Earth dam Plant

17 Z_SOIL.PC DAY 2008 Earthdam Plant

18 Z_SOIL.PC DAY 2008 Absolute displacements, 3D model Earthdam Plant

19 Z_SOIL.PC DAY 2008 Absolute displacements, 3D model Earthdam Settlement = 0.5 cm

20 Z_SOIL.PC DAY 2008 Déplacement absolu [m] T B A Evolution of the settlements for different models

21 Z_SOIL.PC DAY 2008 Summary Settlement analysis of the existing earthdam Global stability analysis Stability analysis of the earthdam (= local) Simplified seismic analysis Work in progress

22 Z_SOIL.PC DAY 2008 Global stability analysis in Z_Soil (one method) Compute problem with given c i and  i in all materials Divide c i and tan( i ) by a factor 1.0, 1.1, 1.2,... … recompute until failure occurs

23 Z_SOIL.PC DAY 2008 SF = 1.50 Global safety factor, 2D analysis

24 Z_SOIL.PC DAY SF = 1.70 Global safety factor, 3D analysis SF = ???

25 Z_SOIL.PC DAY 2008 Summary Settlement analysis of the existing earthdam Global stability analysis Stability analysis of the earthdam (= local) Simplified seismic analysis Work in progress

26 Z_SOIL.PC DAY 2008

27

28 Summary Settlement analysis of the existing earthdam Global stability analysis Stability analysis of the earthdam (= local) Simplified seismic analysis Work in progress

29 Z_SOIL.PC DAY 2008 Introduction 16 m high earth dam is of class III (SFOE guidelines) => Replacement forces analysis can be conducted Global horiz. acceleration: log(a h ) = 0.26 I MSK in cm/s 2 I MSK from seismic intensity maps, T return = 1’000 years Here, a h = 1.65 cm/s 2 = 0.17·g a v = 2/3·a h = 0.11·g (both upwards and (here) downwards)

30 Z_SOIL.PC DAY 2008

31 a h = 0.17 g a v = 0.11 g

32 Z_SOIL.PC DAY 2008 SF = 1.61

33 Z_SOIL.PC DAY 2008 Summary Settlement analysis of the existing earthdam Global stability analysis Stability analysis of the earthdam (= local) Simplified seismic analysis Work in progress

34 Z_SOIL.PC DAY 2008 Work in progress Influence of rain inflow on stability of slopes Steady state and transient 2D and 3D

35 M100 – SC – March 2008 Water table without rain inflow on the material deposit (steady-state analysis)

36 M100 – SC – March 2008 SF = 1.50 Global safety factor, 2D analysis

37 M100 – SC – March 2008 rain inflow: 2 cm / day Water table with rain inflow on the material deposit (steady-state analysis)

38 M100 – SC – March 2008 SF = 1.20 rain inflow: 2 cm / day Global stability study after rain inflow

39 M100 – SC – March 2008 Châtelard deposit. 3D influence of rain inflow. Pore pressures, dry case (no rain)

40 M100 – SC – March 2008 Châtelard deposit. 3D influence of rain inflow. Dry case Progression of displacements with increasing SF

41 M100 – SC – March 2008 Châtelard deposit. 3D influence of rain inflow. Dry case Progression of displacements with increasing SF

42 M100 – SC – March 2008 Châtelard deposit. 3D influence of rain inflow. Dry case Progression of displacements with increasing SF

43 M100 – SC – March 2008 Châtelard deposit. 3D influence of rain inflow. Dry case Progression of displacements with increasing SF

44 M100 – SC – March 2008 Châtelard deposit. 3D influence of rain inflow. Dry case Progression of displacements with increasing SF

45 M100 – SC – March 2008 Châtelard deposit. 3D influence of rain inflow. Dry case Progression of displacements with increasing SF

46 M100 – SC – March 2008 Châtelard deposit. 3D influence of rain inflow. Dry case Progression of displacements with increasing SF

47 M100 – SC – March 2008 Châtelard deposit. 3D influence of rain inflow. Dry case Progression of displacements with increasing SF

48 M100 – SC – March 2008 Châtelard deposit. 3D influence of rain inflow. Dry case Mechanism associated with diverged step. Global safety factor = 3.00


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