2024-03-29_REVISION - M1982121 ‎(2)‎

• Permit No: M1982121
• IBM Index Class Name: Revision
• Doc Date: 3/29/2024
• Doc Name: Adequacy Review Response #2
• From: RMR Aggregates, Inc
• To: DRMS
• Type & Sequence: TR6
• Media Type: D
• Archive: No

KIL D UFF4L RMR Aggregates,Inc.
U N U E R 3 R G U N E. Rock Failure Analyses and Stabilization Report
ENGINEER IN G,INC. Mid Continent Limestone Quarry
and lower limestone slope heights ranging from 5 feet to 15 feet were modeled to determine the
resisting force required to reach a FOS of 1.5 static and 1.3 seismic.
Several mechanical stabilization methods were considered, ultimately a 7-strand anchorage was
selected for both logistical purposes and the stand lengths can be changed to accommodate longer
lengths for this difficult to reach location. In some modeled instances,the upper and lower limestone
could exceed greater than 10 ft thickness which would require a long total length of 45 feet. Given
the load and lengths necessary, a traditional bar would be exceptionally long requiring coupled bars
and likely a crane, becoming logistically cumbersome. A concrete bollard with tie backs was also
considered and has been effectively used locally. However, the concrete bollard would require either
pumping concrete from the base or gravity feed from above. Neither are logistically realistic for the
as-needed local stabilization approach.The 6-inch hole could only be reduced in diameter if the
number of strands was reduced, requiring much longer bond lengths per strand, much longer strands
and therefore a much longer drill hole.The longer drill hole would require a much larger drill rig.
Due to the 6-inch hole diameter and depths required, a berm is needed to resist the upper and/or
lower limestone beds from failing and to be used as a work bench to install the required anchors.
Table 7 below provides details of the necessary anchorage, hole diameter and lengths.
Table 7a. Summary of Required Anchor Stabilization 1,3
Upper& Lower Vertical Horizontal Hale
Limestone Anchorage Spacing Spacing Diameter
Height (ft) (ft) (ft) (in)
10-15 8 strand 10 10 6
5-10 6 strand - 10 6
0-5 4 strand - 30 6
Table 7b.Summary of Required Anchor Stabilization 1.3
Upper& Lower Bond Free Tail Total Lock off
Limestone Length Length Length length Load
Height(ft) (ft) (ft)Z (ft) (ft) (kips)
10-15 18 15 2 35 345
5-10 13 15 2 30 250
0-5 8 15 2 25 185
Notes:
1.Lengths shown are the minimum lengths required.
2. Minimum free length per PTI is 15 feet.
3. Data presented is a preliminary design. Final design of the anchorage system will need
to be performed if required on site.
In order to achieve a higher factor of safety, K U E recommends horizontal drains to be installed
through the joint of the upper and lower limestone if active support is required onsite.
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