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Re: Monday Rambles - link to report
Author: Graham Buxton
Date: 03-03-2010 - 17:38
synonymouse Wrote:
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> The CHSRA faithful claim that this route would
> require a crossing in tunnel of the Garlock fault
> and that this fault is much more likely to cause
> damage than the San Andreas. I have a strong
> suspicion that there is way around this but that
> PB was not interested.
[cahighspeedrail.ca.gov]
The report itself notes potential problems at Garlock, but offers a solution:
4.1.2 Oversized Fault Chambers
The primary fault crossing of concern is at the Garlock Fault. Because of the high likelihood of fault rupture during the life of the facility, preventive measures should be made to avoid an unnecessarily long shut-down of the system after a major earthquake. The maximum displacement on the Garlock Fault is expected to be about nine meters (30 feet), and the expected direction is left lateral. To accommodate this large offset, the tunnel should be oversized, larger than the minimum needed for operation reasons to accommodate track realignment and passage of the train subsequent to a major fault rupture event (see Figure 4-1). A special design must be developed consisting of an enlarged double track tunnel section which takes advantage of the predicted direction and magnitude of fault slippage. After damage from a major earthquake event, this type of tunnel can quickly be returned to service by realigning the tracks.
See page 25, there is also a diagram that illustrates the solution, but it won't paste here.
-------------------------------------------------------
> The CHSRA faithful claim that this route would
> require a crossing in tunnel of the Garlock fault
> and that this fault is much more likely to cause
> damage than the San Andreas. I have a strong
> suspicion that there is way around this but that
> PB was not interested.
[cahighspeedrail.ca.gov]
The report itself notes potential problems at Garlock, but offers a solution:
4.1.2 Oversized Fault Chambers
The primary fault crossing of concern is at the Garlock Fault. Because of the high likelihood of fault rupture during the life of the facility, preventive measures should be made to avoid an unnecessarily long shut-down of the system after a major earthquake. The maximum displacement on the Garlock Fault is expected to be about nine meters (30 feet), and the expected direction is left lateral. To accommodate this large offset, the tunnel should be oversized, larger than the minimum needed for operation reasons to accommodate track realignment and passage of the train subsequent to a major fault rupture event (see Figure 4-1). A special design must be developed consisting of an enlarged double track tunnel section which takes advantage of the predicted direction and magnitude of fault slippage. After damage from a major earthquake event, this type of tunnel can quickly be returned to service by realigning the tracks.
See page 25, there is also a diagram that illustrates the solution, but it won't paste here.
