OVERVIEW PERFORMANCE OF 1. Introduction HOUSES SUBJECTED 2. Project objectives TO BLAST VIBRATIONS 3. Static testing 4. Shaking table specimen design 5. Results - shaking table test 6. Conclusions David Heath 1 Dr. Emad Gad 1,2 Prof. John Wilson 2 1 The University of Melbourne, Victoria, Australia 2 Swinburne University of Technology, Victoria, Australia INTRODUCTION INTRODUCTION “Response of residential structures to blast vibrations” - commenced 2000 - complaints from nearby residents Lilydale Mill Park • Australia – world’s largest exporter of coal Lysterfield • $22.5 billion (AUD) during 2006 – 2007 Kilsyth (19% commodity exports) Bacchus Marsh Colac Geelong Langwarrin • Blasting - fracture rock Wollert - Improves efficiency Pakenham Oaklands Junction 0 500 1000 Scale (metres) 1
MINE AND QUARRY BLASTS PROJECT OBJECTIVES Modes of Response � Identify the relationship between the level of vibration and structural drift � Establish the relationship between drift and damage of non- structural components (Flexural) - Plasterboard (interior) (In-plane) - URM veneer (exterior) � Compare effects of blasting with environmental loads Mine Quarry Blast Blast Blasting Blasting Blasting Blasting � The vibrations travel through the ground in the form of The vibrations travel through the ground in the form of � The vibrations travel through the ground in the form of The vibrations travel through the ground in the form of � � surface and body waves which produce different particle surface and body waves which produce different particle surface and body waves which produce different particle surface and body waves which produce different particle motions in the soil motions in the soil motions in the soil. motions in the soil. Above Above Ground Airblast Ground Structures Structures Subsurface Subsurface Ground Infrastructure Infrastructure Vibration Blast holes 2
Ground Vibration Ground Vibration Ground Vibration Ground Vibration � � Compressive Waves Compressive Waves � Shear Waves � Shear Waves � Denoted as Denoted as P P (Primary) they are the fastest type of (Primary) they are the fastest type of � Denoted as Denoted as S S (Secondary), are the second fastest (Secondary), are the second fastest � � seismic wave. seismic wave. type of seismic wave. type of seismic wave. � Produce particle motion (vibrations) parallel to its Produce particle motion (vibrations) parallel to its � Produce particle motion (vibrations) perpendicular to Produce particle motion (vibrations) perpendicular to � � direction of travel. its direction of travel. direction of travel. its direction of travel. Propagation Direction Ground Vibration Ground Vibration Peak Particle Velocity - Peak Particle Velocity - PPV PPV � � Rayleigh Waves Rayleigh Waves � The peak particle velocity (PPV) is used to represent the The peak particle velocity (PPV) is used to represent the � � Rayleigh waves are slower however they tend to Rayleigh waves are slower however they tend to � intensity of ground vibration. intensity of ground vibration. cause more damage as their particle motion is cause more damage as their particle motion is greater. greater. � PPV is correlated PPV is correlated � � Produce a “elliptical” particle motion. Produce a “elliptical” particle motion. � to damage and to damage and human discomfort. human discomfort . � The intensity of a The intensity of a � blast is governed blast is governed by blast design by blast design = + + V V V V and geological and geological p l t v conditions. conditions. Propagation direction 3
BLAST CHARACTERISTICS VIBRATION STANDARDS “humans are good detectors of vibrations but poor measuring devices” El Centro Typical blast Earthquake vibrations ~20-30sec. 50 40 5mm/s USBM RI 8507 Peak Mine Blast 30 BS 7385-2 Particle ~4sec. Velocity AS 2187.2-1993 (mm/s) 20 ANZEC 5mm/s 10 Quarry Blast ~2sec. 0 1 10 40 100 Frequency (Hz) VIBRATION STANDARDS STATIC TESTING (COMPLETED) Mortar cube Prism tests tests Racking tests (x2) Triplet tests Bond wrench tests 4
TEST HOUSE CONSTRUCTION INSTRUMENTATION Veneer - GP veneer ties - 1:1:6 (C:L:S) mortar - 230x76x110mm extruded clay units - 40mm cavity - 2.3m high masonry - 2.4m x 2.8m in plan - 100x100x6mm EA lintels Frame and Interior - Timber frame - Additional bracing - 1.5T concrete roof mass - Plasterboard interior Photogrammetry model SHAKING TABLE TEST - RESULTS SHAKING TABLE TEST - RESULTS Summary of Test • Total of 564 blasts • Range of intensity: 1 - 383mm/s • First in-plane cracking: - 140mm/s (walls with doors) - 300mm/s (walls with windows) • Other damage: - ties loosened at 85mm/s - flexural cracking at 140mm/s 370mm/s (East-West) 5
NORTH & SOUTH MASONRY DRIFT EAST & WEST MASONRY DRIFT Drift Drift 1/75 1/100 1/100 1/250 1/250 1/500 1/500 SWCA1, SWCB1, NWCB1, SWCC1 NWCB2 EWCB WWCB2, WWCC WWCA1, WWCB1 EWCA SWCA2, SWCA3, SWCC2, SWCD, NWCC SWCB2 Key: EW & WW Key: SW & NW SW fully cracked, NW EW & WW cracked EW & WW fully uncracked uncracked partially cracked cracked EW cracked, WW EW completely cracked, SW & NW partially uncracked WW partially cracked cracked SUMMARY OF DRIFT CONCLUSIONS � A specimen representing a typical brick veneer house has been developed and subjected to simulated uniaxial ground vibrations AS2187.2 Vibration Limits � The threshold drift for the onset of damage has been identified as Human Structural - 1/870 for walls with doors comfort damage - 1/750 for walls with windows Threshold Cracking (less than 1/600 serviceability limit prescribed in Drift, Δ th Drift, Δ cr Δ 5mm/s / Δ th Δ 25mm/s / Δ th Wall AS2870 Residential Slabs and Footings code) North 1/700 1/760 2% 6% � 186mm/s discrepancy at first cracking between the two directions South 1/750 1/370 1% 5% highlights the need for industry displacement based limits East 1/750 1/860 3% 12% � Maximum drift of the test house to vibrations at existing vibration West 1/870 1/390 2% 13% limits was well below the drift at the onset of damage Factor of resistance to cracking 33 7.7 (absence of other loads) � Parametric study in ANSYS (in progress) to further investigate influence of other geometries and material properties Maximum permissible deformation of brick veneer: L/600 (AS2870 Australian Residential Slabs and Footings Code) 6
VIBRATION STANDARDS ACKNOWLEDGEMENTS “humans are good detectors of vibrations but poor measuring devices” • Terrock Consulting Engineers (project partner) Typical blast • ARC linkage grant (No. LP0211407) vibrations • ACARP 50 40 USBM RI 8507 Peak 30 BS 7385-2 Particle Velocity AS 2187.2-1993 (mm/s) 20 ANZEC 10 0 1 10 40 100 Frequency (Hz) 7
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