WEATHERING, ROCK MASS CLASSIFICATION (SSPC), AND REMOTE SENSING WITH A LINK TO LEVEE STABILITY ROBERT HACK ENGINEERING GEOLOGY, ESA, ITC, FACULTY OF GEO-INFORMATION SCIENCE AND EARTH OBSERVATION, UNIVERSITY OF TWENTE, THE NETHERLANDS. PHONE:+31 (0)6 24505442; EMAIL: H.R.G.K.HACK@UTWENTE.NL Fall 2016 Graduate and Undergraduate UMD Civil Engineering Seminar Series University of Minnesota Duluth, Duluth, USA 23 September 2016 CONTENTS      Weathering Rock mass classification Slope Stability Probability Classification (SSPC) Remote sensing of weathering Remote sensing of levees for stability assessment Weathering SSPC levee - Minnesota - Hack 23/09/2016 2 WEATHERING - FUTURE DEGRADATION OF SOIL AND ROCK MASSES Main processes involved in degradation:  Loss of structure due to stress release  Weathering (In-situ change by inside or outside influences)  Erosion (Material transport with no chemical or structural changes) Weathering SSPC levee - Minnesota - Hack 23/09/2016 3 INTACT ROCK WEATHERING 2011 1881 Cleopatra’s needle Central Park, New York Weathering SSPC levee - Minnesota - Hack 23/09/2016 4 FUTURE DEGRADATION OF A SLOPE Weathering SSPC levee - Minnesota - Hack 23/09/2016 5 FUTURE DEGRADATION OF A SLOPE (2) A simple small slope in Spain Rock mass:  Calcareous marls (calcareous clayey, silt) interbedded with very thin limestone beds  Excavated with an excavator at a slope dip of about 70º Weathering SSPC levee - Minnesota - Hack 23/09/2016 6 FUTURE DEGRADATION OF A SLOPE (3) 3.0 1999: 70º 2002: 68º z [m] Reduction in slope angle due to weathering, erosion and ravelling (after Huisman, 2006) 3.5 2.5 2.0 1.5 1.0 7.0 7.5 8.0 Excavated 1999 8.5 9.0 y [m] May 2001 Weathering SSPC levee - Minnesota - Hack 9.5 May 2002 23/09/2016 7 FUTURE DEGRADATION CAUSING SLOPE SLIDING FAILURE Another simple slope in Spain: Rock mass:  Limestone (partially dolomitic) (medium bedded, widely jointed)  Excavated with blasting at a slope dip of about 90º in the 1950’s Weathering SSPC levee - Minnesota - Hack 23/09/2016 8 bedding planes CINDARTO SLOPE: VARIATION IN CLAY CONTENT IN INTACT ROCK CAUSES DIFFERENTIAL WEATHERING April 1990 Slightly higher clay content Slope Weathering Stability SSPC by levee Classification - Minnesota- -Hack Hack 23/09/2016 99 CINDARTO SLOPE VARIATION IN CLAY CONTENT IN INTACT ROCK CAUSES DIFFERENTIAL WEATHERING April 1992 mass slid Slope Weathering Stability SSPC by levee Classification - Minnesota- -Hack Hack 23/09/2016 1010 FUTURE DEGRADATION CAUSING SLOPE SLIDING FAILURE (4) Dissolution of CaCO3 at bedding plane by percolating water, caused reduction of CaCO3 while clay stayed behind; hence bedding plane got an infill of clay-rich material with a lower shear strength than the original CaCO3 bedding plane Weathering SSPC levee - Minnesota - Hack 23/09/2016 11 FUTURE DEGRADATION CAUSING SLOPE SLIDING FAILURE (5) 1991 (dry): φ ≈ 44º coh ≈ 0 kPa 2003 (dry): φ ≈ 23º coh ≈ 9 kPa shearplane Weathering SSPC levee - Minnesota - Hack 23/09/2016 1212 AGAIN ANOTHER SLOPE IN SPAIN Fine-grained limestone (containing some organic material) falls apart in a couple of years from: medium to small cubical blocky structure to very small flaky material Weathering SSPC levee - Minnesota - Hack 23/09/2016 13 Weathering SSPC levee - Minnesota - Hack 23/09/2016 14 How to quantify the influence of weathering and the future influence? Weathering SSPC levee - Minnesota - Hack 23/09/2016 15 ROCK MASS CLASSIFICATION SYSTEMS Classification systems are empirical relations that relate rock mass properties either directly or via a rating system to an engineering application, e.g. slope, tunnel Weathering SSPC levee - Minnesota - Hack 23/09/2016 16 CLASSIFICATION SYSTEMS: Many different classification system developed since the 60’ of the last century for various applications: For underground (tunnels): Bieniawski (RMR), Barton (Q), Laubscher (MRMR), Geological Strength Index (GSI), etcetera For slopes: Selby, Bieniawski (RMR), Vecchia, Robertson (RMR), Romana (SMR), Haines, SSPC, etcetera For excavation: Singh et al. (1987) Etc. Weathering SSPC levee - Minnesota - Hack 23/09/2016 17 EXAMPLE: ROCK MASS RATING (RMR)  Based on a combination of five parameters  Each parameter is expressed by a point rating Weathering SSPC levee - Minnesota - Hack 23/09/2016 18 (from De Mulder et al., 2012) RMR(2) addition of the points results in the RMR rating RMR =(IRS  RQD  spacing  condition  groundwater)  reduction factor (s ) reduction factors for: orientation, excavation damage, etc.  related (empirically) to rock mass cohesion, friction angle of the rock mass, and other rock mass properties (from De Mulder et al., 2012) Weathering SSPC levee - Minnesota - Hack 23/09/2016 19 EXAMPLE: GEOLOGICAL STRENGTH INDEX (GSI) The Geological Strength Index (GSI) is derived from a matrix describing the ‘structure’ and the ‘surface condition’ of the rock mass Weathering SSPC levee - Minnesota - Hack 23/09/2016 20 GSI(2) ‘structure’ is related to the block size and the interlocking of rock blocks ‘surface condition’ is related to weathering, persistence, and condition of discontinuities. (from De Mulder et al., 2012) Weathering SSPC levee - Minnesota - Hack 23/09/2016 21 SLOPE STABILITY PROBABILITY CLASSIFICATION (SSPC) Slope Stability probability Classification (SSPC):  three step classification system  based on probabilities  independent failure mechanism assessment Weathering SSPC levee - Minnesota - Hack 23/09/2016 22 SSPC - THREE STEP CLASSIFICATION SYSTEM (1) proposed new road cut old road river 1 slightly weathered 2 fresh 3 Reference Rock Mass moderately weathered 1: natural exposure made by scouring of river, moderately weathered; 2: old road, made by excavator, slightly weathered; 3: new to develop road cut, made by modern blasting, moderately weathered to fresh. Weathering SSPC levee - Minnesota - Hack 23/09/2016 23 THREE STEP CLASSIFICATION SYSTEM EXPOSURE ROCK MASS (ERM) Exposure rock mass parameters significant for slope stability:  Material properties: strength, susceptibility to weathering  Discontinuities: orientation and sets (spacing) or single  Discontinuity properties: roughness, infill, karst Exposure specific parameters:  Method of excavation  Degree of weathering Factor used to remove the influence of the method excavation and degree of weathering REFERENCE ROCK MASS (RRM) Reference rock mass parameters significant for slope stability:  Material properties: strength, susceptibility to weathering  Discontinuities: orientation and sets (spacing) or single  Discontinuity properties: roughness, infill, karst Slope specific parameters:  Method of excavation to be used  Expected degree of weathering at end of engineering life-time of slope SLOPE GEOMETRY Orientation Height Factor used to assess the influence of the method excavation and future weathering SLOPE ROCK MASS (SRM) Slope rock mass parameters significant for slope stability:  Material properties: strength, susceptibility to weathering  Discontinuities: orientation and sets (spacing) or single  Discontinuity properties: roughness, infill, karst Weathering SSPC levee - Minnesota - Hack SLOPE STABILITY ASSESSMENT 23/09/2016 24 SSPC Excavation specific parameters for the excavation which is used to characterize the rock mass:  Degree of weathering  Method of excavation Weathering SSPC levee - Minnesota - Hack 23/09/2016 25 SSPC Rock mass Parameters:  Intact rock strength  Spacing and persistence of discontinuities  Shear strength along discontinuities: - Roughness - large scale - small scale - tactile roughness - Infill in discontinuities - Karst along discontinuities  Susceptibility to weathering Weathering SSPC levee - Minnesota - Hack 23/09/2016 26 SSPC Slope specific parameters for the new slope to be made:  Expected degree of weathering at end of lifetime of the slope  Method of excavation to be used for the new slope Weathering SSPC levee - Minnesota - Hack 23/09/2016 27 SSPC Intact rock strength (IRS) By simple means test: hammer blows, crushing by hand, etcetera Weathering SSPC levee - Minnesota - Hack 23/09/2016 28 SSPC Spacing and persistence of discontinuities: Determine block size and block form by:  visual assessment, followed by:  quantification (measurement) of the characteristic spacing and orientation of each set Weathering SSPC levee - Minnesota - Hack 23/09/2016 29 SSPC Shear strength – roughness Weathering SSPC levee - Minnesota - Hack 23/09/2016 30 SSPC Infill (In): - cemented - no infill - non-softening (3 grain sizes) - softening (3 grain sizes) - gauge type (larger or smaller than roughness amplitude) - flowing material Weathering SSPC levee - Minnesota - Hack 23/09/2016 31 Discontinuity Condition (TC) factors: CONDITION OF DISCONTINUITY wavy Roughness slightly wavy large scale (Rl) curved (visual area > 0.2 x 0.2 and < slightly curved 1 x 1 m2) straight factor 1.00 0.95 0.85 0.80 0.75 rough stepped/irregular smooth stepped Roughness polished stepped small scale (Rs) rough undulating (tactile and visual on an area smooth undulating of polished undulating 20 x 20 cm2) rough planar smooth planar polished planar 0.95 0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.55 Infill material (Im) cemented/cemented infill no infill - surface staining 1.07 1.00 non softening & sheared material, e.g. free of clay, talc, etc. coarse medium fine 0.95 0.90 0.85 soft sheared material, e.g. clay, talc, etc. coarse medium fine 0.75 0.65 0.55 gouge < irregularities gouge > irregularities flowing material none Weathering SSPC levee - Minnesota - Hack Karst (Ka) karst 0.42 0.17 0.05 23/09/20161.00 32 0.92 SSPC - SHEAR STRENGTH - CONDITION FACTOR Discontinuity condition factor (TC) is a multiplication of the ratings for:     small-scale roughness large-scale roughness infill karst Weathering SSPC levee - Minnesota - Hack 23/09/2016 33 SLIDING CRITERION Condition of Discontinuity (TC) is related to friction along plane by: Rl*Rs*Im*Ka  sliding angle  0.0113 Weathering SSPC levee - Minnesota - Hack 23/09/2016 34 SLIDING CRITERION (EXAMPLE) Bedding dip angle ≈ 35.5º bedding plane description factor large scale straight 0.75 small scale & tactile rough stepped 0.95 infill fine soft sheared 0.55 karst none 1.00  sliding angle  Rl*Rs* Im*Ka 0.75* 0.95* 0.55*1.00   35 degrees 0.0113 0.0113 Weathering SSPC levee - Minnesota - Hack 23/09/2016 35 SSPC’S ROCK MASS PROPERTIES Rock mass properties derived from SSPC system:  Condition of discontinuity (“sliding angle”)  Rock mass angle of internal friction  Rock mass cohesion Weathering SSPC levee - Minnesota - Hack 23/09/2016 36 Quantification of weathering influence Weathering SSPC levee - Minnesota - Hack 23/09/2016 37 IMPACT OF WEATHERING From: De Mulder, E.J.F., Hack, H.R.G.K., Van Ree, C.C.D.F., 2012. Sustainable Development and Management of the Shallow Subsurface. The Geological Society, London. ISBN: 978-1-86239-343-1. p. 192. Weathering SSPC levee - Minnesota - Hack 23/09/2016 38 But if possible to assess the influence quantitatively than also the relation with time if the time of exposure is known Weathering SSPC levee - Minnesota - Hack 23/09/2016 39 TIME RELATION - WEATHERING The susceptibility to weathering is a concept that is frequently addressed by “the” weathering rate of a rock material or mass. Weathering rates may be expected to decrease with time, as the state of the rock mass becomes more and more in equilibrium with its surroundings. Weathering SSPC levee - Minnesota - Hack 23/09/2016 40 WE  t   WEinit  R app WE log 1  t  WE(t) = degree of weathering at time t WEinit = (initial) degree of weathering at time t = 0 RappWE = weathering intensity rate WE as function of time, initial weathering and the weathering intensity rate Weathering SSPC levee - Minnesota - Hack 23/09/2016 41 WEATHERING RATES •Material: Gypsum layers Gypsum cemented siltstone layers Middle Muschelkalk near Vandellos (Spain) Slope Weathering Stability SSPC by levee Classification - Minnesota- -Hack Hack 23/09/2016 4242 SSPC system with applying weathering intensity rate:  - original slope cut about 50º (1998)  - in 15 years decrease to 35º Weathering SSPC levee - Minnesota - Hack 23/09/2016 43 KOTA KINABALU, MALAYSIA 10 years old (after -Tating, & Jetten, 2011) 4444 Weathering SSPC levee - Minnesota Hack Hack, 23/09/2016 KOTA KINABALU Side road (dip 45°, 5 years old) sandstone: slightly weathered SSPC stability: Sandstone: stable (92%) Shale: unstable (< 5%) Weathering SSPC levee - Minnesota - Hack 23/09/2016 45 KOTA KINABALU Main road (dip 30°, 10 years old): sandstone: moderately weathered SSPC stability: Sandstone: stable (95%) Shale: ravelling (<5%) 10 years old Weathering SSPC levee - Minnesota - Hack 23/09/2016 46 KOTA KINABALU time [years] dip [degrees] unit SSPC visual RM friction RM cohesion [degrees] [kPa] shale Slightly weathered 5 45 4 2.4 unstable Moderately weathered 10 30 2 1.1 unstable Slightly weathered 5 45 20 10.0 stable Moderately weathered 10 30 11 6.3 stable sandstone Weathering SSPC levee - Minnesota - Hack 23/09/2016 47 SSPC SSPC system in combination with degradation forecasts gives:     reasonable design for slope stability with minimum of work and in a short time (likely a reasonable tool to forecast susceptibility to weathering) Weathering SSPC levee - Minnesota - Hack 23/09/2016 48 REMOTE SENSING Remote sensing to detect weathering and weathering state:  Possibly from UAV’s (drones)  Also inaccessible areas can be investigated Weathering SSPC levee - Minnesota - Hack 23/09/2016 49 WEATHERING – TEMPERATURE REMOTE SENSING Thermotracer (thermal infra-red) Weathering SSPC levee - Minnesota - Hack 23/09/2016 50 WEATHERING – TEMPERATURE REMOTE SENSING Lidar visual Termal infra-red (after Kekeba, 2008) More weathered rock has higher porosity: contains more water: takes a longer time to heat in the morning than less weathered rock Weathering SSPC levee - Minnesota - Hack 23/09/2016 51 LEVEES If remote sensing is an option to establish weathering than also it may be to establish geology in levees Weathering SSPC levee - Minnesota - Hack 23/09/2016 52 OPTIONS WITH REMOTE SENSING Lidar (geometry) Thermal Infrared (temperature differences, humidity) Multi-spectral (vegetation, type of ground, humidity) Weathering SSPC levee - Minnesota - Hack 23/09/2016 53 REFLECTANCE VERSUS VEGETATION STRESS Weathering SSPC levee - Minnesota - Hack 23/09/2016 54 REFLECTANCE VERSUS VEGETATION STRESS  Vegetation stress may be due to:  Excess water  Shortage water  Vegetation unfriendly minerals or fluids (environmental pollution) Shortage or excess of water may indicate weak areas in a dike Weathering SSPC levee - Minnesota - Hack 23/09/2016 55 PEAT EXCAVATION  The Reeuwijk area is a typical “polder” area in the peat excavation region of Zuid-Holland, The Netherlands  Peat has been excavated for fuel and sometimes table salt since the early Medieval times (since 800 AD)  Peat was excavated “under water” by scooping the peat down to a depth of about 4 - 6 m below the water level  The peat was brought by boat to not-excavated strips of land with paths and roads left behind inbetween the excavation areas Exercise 3D GIS - CTG minor Water - Hack 13/09/2016 56 a b Visual images of Tempeldijk-South showing the difference in the apparent surface roughness in: (a) August 15, 2007, (b) October 31, 2007 and (c) December 13, 2007 c Weathering SSPC levee - Minnesota - Hack 23/09/2016 57 POLDER In the 16th through 19th centuries, land shortage and increasing prices for agricultural land triggered pumping-out the water from the lakes by windmills; the “polders” were created Exercise 3D GIS - CTG minor Water - Hack 13/09/2016 58 SUBSURFACE GEOLOGY - TEMPELDIJK-SOUTH LOCATION Exercise 3D GIS - CTG minor Water - Hack 13/09/2016 59 TEMPERATURE a a b b c c Weathering SSPC levee - Minnesota - Hack 23/09/2016 60 GEOLOGY - HUMIDITY Weathering SSPC levee - Minnesota - Hack 23/09/2016 61 After Cundill et al, 2012 CONCLUSIONS  Weathering can be quantified with help of rock mass classification systems  SSPC seems suitable  Quantified effects of weathering can be forecasted  Remote sensing may be an option to establish different degrees of weathering  Remote sensing may (with the same methodology) be suitable to detect weak areas in levees Weathering SSPC levee - Minnesota - Hack 23/09/2016 62 REFERENCES                   Cundill, S. L., M. Meijde, and H. R. G. K. Hack. 2014. "Investigation of Remote Sensing for Potential Use in Dike Inspection." Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of 7 (2):733-46. doi: 10.1109/jstars.2013.2293617. Cundill, S. L., H. M. A. van der Werff, and M. van der Meijde. 2014. "Cross-Calibration of Indices by Spectrally Convolving Field Spectra to Simulate Very High Spatial Resolution Sensors." Manuscript submitted for publication. Cundill, S.L., H.R.G.K. Hack, M. van der Meijde, J. van der Schrier, and D.J.M. Ngan-Tillard. 2013. "Quality of peat dykes evaluated by remote sensing." In: Comprehensiver flood risk management / ed. by. F. Klijn and T. Schweckediek. London : Taylor & Francis, 2013. ISBN 978-0-415-62144-1. pp. 463-469. De Mulder, E.J.F., Hack, H.R.G.K., Van Ree, C.C.D.F., 2012. Sustainable Development and Management of the Shallow Subsurface. The Geological Society, London. ISBN: 978-1-86239-343-1. p. 192. Hack, H.R.G.K., 2002. An evaluation of slope stability classification; Keynote lecture. In: Dinis Da Gama, C., Ribeira E Sousa, L. (Eds) ISRM EUROCK 2002, Funchal, Madeira, Portugal. Sociedade Portuguesa de Geotecnia, Av. do Brasil, 101, 1700-066 Lisboa, Portugal, pp. 3–32. Hack, H.R.G.K., Price, D.G., Rengers, N., 2003. A new approach to rock slope stability : a probability classification SSPC. Bulletin of Engineering Geology and the Environment. 62 (2). DOI: 10.1007/s10064-002-0155-4. pp. 167-184. Hack, H.R.G.K., Price, D., Rengers, N., 2005. Una nueva aproximación a la clasificación probabilística de estabilidad de taludes (SSPC). In: Proyectos, U.D., Minas, E.T.S.I. (Eds), Ingeniería del terreno : ingeoter 5 : capítulo 6. Universidad Politécnica de Madrid, Madrid. ISBN: 84-96140-14-8. p. 418. (in Spanish) Hack, H.R.G.K., Price, D.G. & Rengers, N., 2003. 研究岩质边坡稳定性新方法—概率分级法 (Translation of "A new approach to rock slope stability - A probability classification (SSPC)"). Original in: Bulletin of Engineering Geology and the Environment. 62 (2). DOI: 10.1007/s10064-002-0155-4. ISSN: 1435-9529; 1435-9537. pp. 167-184. (in Chinese) Hack, H. R. G. K., M. van der Meijde, J. S. van der Schrier, Y. H. Awaju, J. Rupke, S. Barritt, J. van 'T Hof, et al. 2008. "Strength of peat dykes evaluated by remote sensing (Gebiedsdekkende dijksterkte bepaling met remote sensing): Pilot project: RSDYK2008, Program Flood Control 2015." In, 135. Delft: Flood Control 2015 Hoek, E., Marinos, P., Benissi, M., 1998. Applicability of the geological strength index (GSI) classification for very weak and sheared rock masses. The case of the Athens Schist Formation. Bulletin of Engineering Geology and the Environment. 57 (2). DOI: 10.1007/s100640050031. pp. 151-160. Huisman, M., Hack, H.R.G.K., Nieuwenhuis, J.D., 2006. Predicting Rock Mass Decay in Engineering Lifetimes: The Influence of Slope Aspect and Climate. Environmental & Engineering Geoscience. 12 (1). DOI: 10.2113/12.1.39. pp. 39-51. Kekeba, A.D., 2008. Establishing relationship between thermal radiation and intensity of 3D terrestrial laser scan data of weathered rock surface for sloper stability analysis. Hack, H.R.G.K. & Van Der Meijde, M. (Advs). MSc thesis. Engineering Geology, University Twente-ITC, Enschede, The Netherlands. p. 84. Marinos, P., Hoek, E., 2000. GSI: A geologically friendly tool for rock mass strength estimation. In: Drinan, J., Geom Australian (Eds) GeoEng2000 - International Conference on Geotechnical & Geological engineering, Melbourne, 19-24 November 2000. Technomic Publishing Co, Lancaster, PA, USA, pp. 1422–1446. Marinos, V., Marinos, P. & Hoek, E. 2005. The geological strength index: applications and limitations. Bull. of Engineering Geology and the Environment 64/1, doi: 10.1007/s10064-004-0270-5, 55-65. Price, D.G., De Freitas, M.H., Hack, H.R.G.K., Higginbottom, I.E., Knill, J.L., Maurenbrecher, M., 2009. Engineering geology : principles and practice. De Freitas, M.H. (Ed.). Springer-Verlag, Berlin, Heidelberg. ISBN: 978-3-540-29249-4. p. 450. Tating, F.F., Hack, H.R.G.K. & Jetten, V., 2013. Engineering aspects and time effects of rapid deterioration of sandstone in the tropical environment of Sabah, Malaysia. Engineering Geology. 159. DOI: 10.1016/j.enggeo.2013.03.009. ISSN: 0013-7952. pp. 20-30. Tating, F.F., Hack, H.R.G.K. & Jetten, V., 2015. Weathering effects on discontinuity properties in sandstone in a tropical environment: case study at Kota Kinabalu, Sabah Malaysia. Bulletin of Engineering Geology and the Environment. 74 (2). DOI: 10.1007/s10064-014-0625-5. ISSN: 1435-9529. pp. 427-441. White, A.F., Blum, A.E., Schulz, M.S., Vivit, D.V., Stonestrom, D.A., Larsen, M., Murphy, S.F., Eberl, D., 1998. Chemical Weathering in a Tropical Watershed, Luquillo Mountains, Puerto Rico: I. Long-Term Versus Short-Term Weathering Fluxes. Geochimica et Cosmochimica Acta. 62 (2). DOI: 10.1016/s0016-7037(97)00335-9. pp. 209-226. Weathering SSPC levee - Minnesota - Hack 23/09/2016 63