Evaluation of the behaviour of an arch-gravity dam featuring a - PowerPoint PPT Presentation

Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack Dr Aïssa Mellal, Civil Engineer STUCKY SA, Switzerland NUMERICS IN GEOTECHNICS AND STRUCTURES - ZSoil Days - 1-2 September 2011, Lausanne

Spitallamm Dam l = 258 m h = 114 m Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Objectives 1. Crack Identification 2. Reliable Numerical Model of the Dam (incl. THM calibration) 3. Seismic safety assessment Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Crack location and measurements 1900 1880 Cement grout 1860 1840 1820 Cement grout 1800 Section 3a Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Crack location and measurements Crack zone 6a 6 5a 5 4a 4 3a 3 2a 2 1a 1 0a 1908.74 m 1900.74 m 1899.74 m Block 3a Block 3a Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Inclinometer measurements Upstream-Downstream Displacements Measures with inclinometer Displacement [mm] Displacement [mm] US DS US DS -35 -30 -25 -20 -15 -10 -5 0 5 -35 -30 -25 -20 -15 -10 -5 0 5 0 6 5 4 3a 3 2 1 0 1911.24 Crest 1900 5 5 1885.0 Depth from dam crest [m] 1880 Depth from dam crest [m] B4 B3 B1& B2 1860 10 10 1840 1820 RIGHT BANK LEFT BANK 15 15 1800 Downstream view 20 20 Initial measure: 01.10.1996 Borehole B3, RIGHT Borehole B1, CENTER UPSTREAM Reservoir level: 1898.90 Range 2005 Range 2004 25 25 Reference measure: Range 2003 04.03.1997 Range 2002 Displacement [mm] Displacement [mm] Reservoir level: 1862.36 US DS US DS Range 2001 -35 -30 -25 -20 -15 -10 -5 0 5 -35 -30 -25 -20 -15 -10 -5 0 5 1911.24 Crest 0 0 5 5 Depth from dam crest [m] Boreholes B2, B3 and B4 Borehole B1, Center Depth from dam crest [m] 10 10 15 15 20 20 Borehole B4, LEFT Borehole B2, CENTER DOWNSTREAM 25 25 Face concrete "Trog" concrete 1885.0 Mass concrete Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Crack location and measurements 1900 1880 1860 1840 1820 1800 Section 3a Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Numerical modelling approach 3D Model 3D Model TM Transient Thermal Mechanical Coupling analysis analysis 3D FE Model dam incl. crack + foundation Thermal Displacement calibration calibration Static and dynamic Stability analysis evaluation global and local Retrofit proposal Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Geometry and Finite element mesh (3D) Concrete: Linear elastic Pre-existing crack: Frictional contact Solid BC Rock: Linear elastic Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Tensile (major principal stress) stress fields Full reservoir – No thermal effects Zone of potential horizontal cracking Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Progressive crack opening Full reservoir – no thermal effects No crack model Horizontal crack model Complete crack model S1=190 kPa S1=80 kPa S1=20 kPa S1: major principal (tensile) stress Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Crack configuration at the interface Face / Intermediate concrete 4 3a 3 1900.74 m 4a 2a 1899.74 m 2 5 1a 5a 1 6 0a 6a Pre-existing crack zone 1830 m Section 3a Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Loading condition Combined effects Water level + Air-water temperature + solar radiation Air temperature + upstream solar radiation Air temperature + downstream solar radiation Varying level Water temperature Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Thermal evolution 2008 February May August November UNIT [°C] Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Results of thermal analysis Comparison with the measurements Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Results of thermal analysis Comparison with the measurements Sec. 3a T1 (T1) Sec. 3a T2.1 (T2) Measured Model Measured Model 14.0 14.0 12.0 12.0 10.0 10.0 8.0 Temperature (°C) 8.0 Temperature (°C) 6.0 6.0 4.0 4.0 2.0 2.0 0.0 0.0 -2.0 -2.0 -4.0 -4.0 -6.0 -6.0 Time (date) Time (date) Sec. 3a T2.2 (T3) Measured Model Sec. 3a T2.3 (T4) Measured Model 14.0 14.0 12.0 12.0 10.0 10.0 8.0 8.0 Temperature (°C) Temperature (°C) 6.0 6.0 4.0 4.0 2.0 2.0 0.0 0.0 -2.0 -2.0 -4.0 -4.0 -6.0 -6.0 Time (date) Time (date) Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Results of thermal analysis Comparison with the measurements Sec. 3a T3.1 (T5) Sec. 3a T3.2 (T6) Measured Model Measured Model 14.0 14.0 12.0 12.0 10.0 10.0 8.0 8.0 Temperature (°C) Temperature (°C) 6.0 6.0 4.0 4.0 2.0 2.0 0.0 0.0 -2.0 -2.0 -4.0 -4.0 -6.0 -6.0 Time (date) Time (date) Sec. 3a T3.3 (T7) Sec. 3a T3.4 (T8) Measured Model Measured Model 14.0 14.0 12.0 12.0 10.0 10.0 8.0 8.0 Temperature (°C) Temperature (°C) 6.0 6.0 4.0 4.0 2.0 2.0 0.0 0.0 -2.0 -2.0 -4.0 -4.0 -6.0 -6.0 Time (date) Time (date) Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Thermo-mechanical analysis Model vs. measured displacement Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Thermo-mechanical analysis Model vs. measured displacement Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Thermo-mechanical analysis Model vs. measured displacement (with assumed linear deviation) Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Thermo-mechanical analysis Crack Opening Model vs. joint meter measurements (with assumed linear deviation) Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Crack opening Extreme US calculated displacement: 18.65 mm (13.08.2003) Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland

Crack opening Major principal stress at crack tip: (+) Tensile / (-) Compressive stresses Evaluation of the behaviour of an arch-gravity dam featuring a pre-existing crack A. Mellal Numerics in Geotechnics and Structures 2011 - Z_Soil Days - 1-2 September 2011, Lausanne, Switzerland