itw2008: p. campus, r. oldfield bermuda, 3-7 november 2008 the recently installed ims infrasound...

ITW2008: P. Campus, R. Oldfield Bermuda, 3-7 November 2008

The recently installed IMS Infrasound Station IS51, Bermuda

Paola CampusComprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) IMS, Engineering and Development Section, Acoustic Monitoring Projecte-mail: [email protected]

Roger Oldfield, Eng.Telecom Consultante-mail: [email protected]



The installation of IS51 is the result of a very efficient teamwork

involving the Bermuda Government, Local and Overseas Companies and

Consultants, who provided the Provisional Technical Secretariat of CTBTO with a crucial contribution

to the realization of the project


Cabinet Conclusion number 23(07)7 dated 19 June 2007 indicating the Cabinet’s approval

for the establishment of an Infrasound Monitoring Station IS51 at five sites in

Bermuda


Installation: July 2008


Location of IS51 in Bermuda


Installation works, July 2008


Examples of infrasound signals recorded at

IS51


Natural events


Storm


IS51:


Can IS51 help track hurricanes in the future?


Man-made events


Flight activity


IS51: Flight activity


Quarry blasting


IS51: Wilkinson Quarry ~400m from H4


Old Club Med Implosion


Club Med Demolition St. George, Bermuda

25th August, 2008


Interior Demolition

• All asbestos containing materials has been removed from the building

• The internal demolition included the following:

– Removal of all Non-Load Bearing Walls

– Removal of any remaining debris

– Removal of all material, leaving only the structural members


Before

After


The Implosion Process

The building will not be blown up.

Explosives will be used as a tool to displace selected load-bearing members in a controlled sequence to cause a progressive collapse of the structure within the building footprint.

Total weight of Explosives was 730 lbs 2,030 sticks of Dynamite or Explosive Charges


Columns

Pre-determined columns will be drilled and prepared for the placement of explosives.

Explosives will displace the selected load bearing columns.

Typical Charge Placement with plug and detonator.


•Over 1,700 horizontal bore holes will be drilled at column and wall positions.

• Holes will provide acceptance for predetermined quantities of high explosives.

•Holes will be drilled roughly 2/3’s the depth of the column. Explosives will be place in the holes and then plugged with a sealing material.


Walls

Secondary masonry wall units on the lower two levels and selected upper floor level will be modified. Modification is to include making columns in shear walls, elevator shafts, and stairwells.

Selected sections of the end walls will be modified in order to create planes of failure for the east and west wings of the structure.


Protection

• Covering Protection will be installed on/around the structure to create a blast curtain.

• Approximately 35,000 square feet of 11 ½ - gauge fencing and 80,000 square feet of geo-textile fabric will be used for protection.


Vibrations

The performance phase of the explosive demolition work will create a 7-second duration per an “Impact Event.” During this relatively concise demolition period three physical force types will actively emerge and produce their respective levels of vibration and air over-pressure values. The following are the stated forces as they relate to blast data criteria:

1. Air Transmitted Over-Pressure (Concussion)

2. Vibration per Explosive Detonation

3. Dynamic Compaction per Structural Collapse


Seismic Monitoring

A geological firm will be employed to perform pre-blast survey inspections on selected adjacent properties prior to the scheduled demolition date. The survey will address the stated area and document their findings per existing conditions.

The same firm will then conduct a post-blast survey to inspect the post-blast conditions of the selected areas around the site.

Seismographs will be placed in strategic locations, which will surround this structure and monitor the seismic impact of the event which will provide us with the magnitude of both vibrations and air over-pressure.

Seismic Locations and Readings: #1 was placed 381ft North West of Blast Site - 0.35in/s at 64 Hz, >148 dB#2 was placed 390 ft North of Blast Site - 0.17in/s at 64 Hz, >148 dB#3 was placed 690 ft South East of Blast Site - <0.10in/s at 64Hz, <125 dB#4 was placed 175 ft South West of Blast Site – 0.16in/s at 23 Hz, 141.8 dB


Implosion video link:F:\ITW 2008\presentations\Session 3 - The International Monitoring System\3-05 Campus Oldfield\VIDEO_TS\VTS_01_0.IFO


Results of analysis of data recording the Club Med Hotel implosion on the 25th August, 2008 using the

Progressive Multi-Channel Correlation technique

Data filtered between 0.4 and 8 Hz


IS51: Old Club Med implosion 2008/08/25: location of Old Club Med and of IS51


IS51: Old Club Med implosion 2008/08/25


IS51: Old Club Med implosion 2008/08/25 Detail of waveforms


IS51: Old Club Med implosion 2008/08/25


Implosion video link:F:\ITW 2008\presentations\Session 3 - The International Monitoring System\3-05 Campus Oldfield\VIDEO_TS\VTS_01_0.IFO


IS51: potential for detection of a large number of events


Thank you

itw2008: p. campus, r. oldfield bermuda, 3-7 november 2008 the recently installed ims infrasound...

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