Nanometrics Trillium Compact, Руководство пользователя

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The recommended concrete mixture is 50 percent Portland cement and 50 percent sieved
sand.
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After pouring the concrete, shake it to allow trapped bubbles to escape. Allow 24 hours
for the concrete to harden before positioning the seismometer on the pier.
The pier may generate spurious signals as the concrete cures, which can take two to
four weeks.
3.5.2 Decoupling the Pier and Vault Walls
When setting up the concrete forms for the pier, include a gap between the edge of the
concrete and the walls of the vault. Decoupling the pier and the vault walls prevents the
transfer of non-seismic forces, such as those generated by surface winds, from the vault walls
to the pier. Such forces can cause the pier to tilt or twist and obscure the desired seismic
signal. These signals are mostly long period, so vault wall decoupling is critical for quiet site
long period studies.
3.6 Alignment, Leveling, and Placement Features
To aid in the proper alignment of your seismometer, each Trillium Compact Vault has:
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Vertically-scribed marks on the north-south axis.
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A north-south guide on the top of the case.
"Features and Dimensions" on page 82 provides illustrations that show the relative
orientation of the east-west and north-south alignment features in top, bottom and side
views.
For leveling purposes, each Trillium Compact Vault seismometer is equipped with:
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Three adjustable-height feet with lock nuts. A 2.5 mm hex screwdriver works well to
tighten the lock nuts in place.
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Bob Uhrhammer and Bill Karavas, Guidelines for Installing Broadband Seismic Instrumentation
(Berkeley: The Regents of the University of California, 1997),
http://seismo.berkeley.edu/bdsn/instrumentation/guidelines.html.
Chapter 3 - Installing a Trillium Compact Vault Seismometer
16889R10 • 2020-11-12 Page 36