See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/267158596 PRESENTATION ONLY: Instrumentation and Monitoring during Construction of the Ingula Powerhouse Caverns Conference Paper · December 2010 CITATION READS 1 99 3 authors , including: Gerhardus J Keyter SRK Consulting (South Africa) Pty Ltd 19 PUBLICATIONS 56 CITATIONS SEE PROFILE All content following this page was uploaded by Gerhardus J Keyter on 26 August 2015. The user has requested enhancement of the downloaded file.
BRAAMHOEK CONSULTANTS JOINT VENTURE THE INGULA PUMPED STORAGE SCHEME INSTRUMENTATION AND MONITORING DURING CONSTRUCTION OF THE INGULA POWERHOUSE CAVERNS December 2010 BY G Keyter, M Kellaway & D Taylor
BRAAMHOEK CONSULTANTS JOINT VENTURE PRESENTATION OVERVIEW • POWERHOUSE COMPLEX • SIMPLIFIED GEOLOGY OF THE POWERHOUSE COMPLEX • ANALYSIS AND DESIGN • INSTRUMENTATION DESIGN • TRIGGER LEVELS • INSTRUMENTATION • CONVERGENCE • DESIGN VERIFICATION • COMPARISON BETWEEN ANTICIPATED AND ACTUAL CONVERGENCE
BRAAMHOEK CONSULTANTS JOINT VENTURE INGULA POWERHOUSE COMPLEX Machine Transformer Hall Hall
BRAAMHOEK CONSULTANTS JOINT VENTURE SIMPLIFIED POWERHOUSE GEOLOGY • VOLKSRUST Fm (UPPER ECCA GROUP, KAROO SUPERGROUP) 250-260my • thinly laminated siltstones, mudstones and carbonaceous mudstones. • UCS 90MPa (41 – 123MPa), • durability reduces with depth from overlying dolerite sill. • KAROO DOLERITE SUITE • sub horizontal dolerite sills and sub vertical dykes along existing faults or shear planes. Hydrothermal veining. • STRUCTURAL GEOLOGY • sub horizontal bedding shear planes with brecciated, soft rock infill • normal faulting.
BRAAMHOEK CONSULTANTS JOINT VENTURE SIMPLIFIED POWERHOUSE GEOLOGY
BRAAMHOEK CONSULTANTS JOINT VENTURE SIMPLIFIED POWERHOUSE GEOLOGY
BRAAMHOEK CONSULTANTS JOINT VENTURE SIMPLIFIED POWERHOUSE GEOLOGY Locally thinning out
BRAAMHOEK CONSULTANTS JOINT VENTURE ANALAYSIS & DESIGN Focus on: Example : UDEC model of Transformer Hall Cavern • Optimizing crown geometry • Stability, particularly of machine hall with 26m span • Effects of seismic loading BEDDING SHEAR • Long term creep effects • Methods of excavation & support • Excavation & support sequencing Using: • Kinematics: DIPS & Unwedge Example : Phase2 model of Powerhouse Caverns • Continuum: Phase2 V6 & FLAC3D • Discontinuum: Phase2 V7, UDEC & 3DEC Note: UDEC, 3DEC & FLAC3D work done in close cooperation with Tony Leach at Itasca External review: • Dr Evert Hoek
BRAAMHOEK CONSULTANTS JOINT VENTURE EXCAVATION OF TOP HEADING
BRAAMHOEK CONSULTANTS JOINT VENTURE EXCAVATION OF BENCH 1
BRAAMHOEK CONSULTANTS JOINT VENTURE EXCAVATION OF BENCH 2
BRAAMHOEK CONSULTANTS JOINT VENTURE INSTRUMENTATION DESIGN • Located where greatest displacement is expected • On site design optimisation to assess the loading on support elements.
BRAAMHOEK CONSULTANTS JOINT VENTURE INSTRUMENTATION DESIGN MHTH THTH Bench 1 Bench 1 Bench 2
BRAAMHOEK CONSULTANTS JOINT VENTURE CAVERN TRIGGER LEVELS • Primary Support Cavern crown and sidewalls • Relate to the projected increase in convergence between subsequent excavation stages 30 ALARM LEVEL 25 WARNING LEVEL 20 Convergence (mm) Time of secondary support installation BASELINE LEVEL Time of primary support installation 15 10 Projected convergence 5 Convergence measurements 0 Time Convergence Trigger Levels in the Cavern Crowns
BRAAMHOEK CONSULTANTS JOINT VENTURE MACHINE HALL TRIGGER LEVELS • Secondary support in MH Cavern; • Relate to the projected TOTAL convergence with time as cavern excavation progresses; • Measured at different points; • Working loads as measured in cable bolts and cable anchors; • Serve as a GUIDELINE; • A FULL ASSESSMENT OF THE STABILITY would require an assessment of the encountered ROCK MASS, quality of WORKMANSHIP and PERFORMANCE of support elements.
MH Crown Convergence (mm) MACHINE HALL TRIGGER LEVELS 105 120 135 150 BRAAMHOEK CONSULTANTS JOINT VENTURE 15 30 45 60 75 90 0 Relax ahead of CH, zero point for monitoring Rockbolts installed @ face in CH Cable bolts installed in CH crown Relax ahead of side headings Cable bolts installed in side headings Cable anchors installed in CH crown Relax ahead of 1st bench Cable bolts installed in 1st bench Cable anchors installed in side headings Relax ahead of 2nd bench Cable bolts installed in 2nd bench Cable anchors installed in 1st bench Excavated Invert Level (masl) ALARM LEVEL WARNING LEVEL Relax ahead of drainage gallery GRPs installed in drainage gallery Relax ahead of 3rd bench Cable bolts installed in 3rd bench Cable anchors installed in 2nd bench Relax ahead of 4th bench Cable bolts installed in 4th bench Cable anchors installed in 3rd bench Relax ahead of 5th bench Cable bolts installed in 5th bench Cable anchors installed in 4th bench Relax ahead of 6th bench Cable bolts installed in 6th bench Cable anchors installed in 5th bench Relax into turbine pits Cable bolts & floor dowels installed in turbine pits Cable anchors installed in 6th bench Cable anchors installed into turbine pits Convergence Envelope Expected Primary support removed Long term creep 1160 1166 1172 1178 1184 1190 1196 1202 1208 1214 1220 Excavated Cavern Invert Level (masl)
BRAAMHOEK CONSULTANTS JOINT VENTURE INSTRUMENTATION • MULTIPLE POINT BOREHOLE EXTENSOMETERS
BRAAMHOEK CONSULTANTS JOINT VENTURE INSTRUMENTATION • INSTRUMENTED ROCK BOLTS, CABLE BOLTS AND CABLE ANCHORS
BRAAMHOEK CONSULTANTS JOINT VENTURE CONVERGENCE DATA
BRAAMHOEK CONSULTANTS JOINT VENTURE ON SITE DESIGN VERIFICATION • Scheduling the installation of instrumentation following review of encountered ground. • Review of Convergence Data • Initial review of data, identify any problems etc. • Assessing Reliability of Data (ground movement or other) • Scheduling Readings (Frequency) • High level summary – provide OVERVIEW & IDENTIFY POTENTIAL PROBLEM AREAS. • Review by Designer & external Design Reviewer (DR. EVERT HOEK).
BRAAMHOEK CONSULTANTS JOINT VENTURE DESIGN VERIFICATION
BRAAMHOEK CONSULTANTS JOINT VENTURE MH E4 ARRAY MHTH Bench 1 THTH Bench 2 Bench 1 Bedding Shears
BRAAMHOEK CONSULTANTS JOINT VENTURE PROVISIONAL COMPARISON OF CONVERGENCE DATA
BRAAMHOEK CONSULTANTS JOINT VENTURE PROVISIONAL COMPARISON OF CONVERGENCE DATA
BRAAMHOEK CONSULTANTS JOINT VENTURE PROVISIONAL COMPARISON OF CONVERGENCE DATA
BRAAMHOEK CONSULTANTS JOINT VENTURE POSSIBLE REASONS FOR DIFFERENCES IN EXPECTED AND ACTUAL CONVERGENCE • Sequence of excavation incl. overall sequence for PH complex • Support sequence – bringing forward the installation of cable anchors • Profile changes and variations in shotcrete support thickness • Performance of the support • Reliability of geotechnical instrumentation readings. • Local variations in the geology
BRAAMHOEK CONSULTANTS JOINT VENTURE MACHINE HALL View publication stats View publication stats
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