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RE: Road Repair Advice Needed
- To: <seaint(--nospam--at)seaint.org>
- Subject: RE: Road Repair Advice Needed
- From: "Arvel L. Williams, P.E." <awilliams(--nospam--at)gwsquared.com>
- Date: Wed, 16 Mar 2005 10:13:34 -0600
about a pattern of screw anchors under the rock extending under the roadway
anchored in bedrock. I've done this on a 26 foot cut supporting a 3 story
apartment and 20 feet of retained soil upgrade. Only downside is that the
rock wall would need to be pulled down in 5 foot increments and then the anchors
installed. After installation your cut use shotcrete to fake a new
rocklike wall or replace the original rock wall in front of the screw
I have a client who is purchasing two lots for two
custom homes in the foothills of a mountain overlooking a golf course in
Palm Springs. There is an old road about 300 feet long that makes the climb to
the property; one side of the road is a rock hillside cut for the road years
ago. The other side that is seen from below is simply stacked stone slabs
retaining soil. The maximum height of the unsupported roadway (or that which
is supported by the gravity wall of stacked stone slabs) was determined by the
geotechnical engineer to be insufficient for heavy utility vehicles such as a
fire truck that must be allowed access to the lots above.
I have not seen
the road but the City is adamant about keeping the appearance of the stone
wall. I discussed some choices with soil engineer but will not have any design
values until sometime next week. His thoughts followed mine, but these seem
rather expensive solutions for access to the two custom home lots:
Install Soldier Piles behind the existing stacked rock that would need to be
drilled at the most, ten feet into bedrock and would be tied by one or more
beams that would help retain and support the roadway. The potential down side
is that the coring of the soldier piles may "blow out" the stone wall in which
case it would need to be repaired.
2. design a retaining wall behind the
existing stone wall that sets on embedded piles and grade beams and then work
some veneer ties into the stacked stone. Again, the piles would be about ten
feet deep into bedrock at this time and the wall would need to transfer
rotation to the grade beam and top of piles.
3. Trench behind the existing
stacked stone and shore sufficiently to allow a conventional "L" shaped
retaining wall to be constructed, backfill and compact. This would avoid the
need to core piles but would require the removal of more soil to allow the
design of a more conventional wall with an adjacent surcharge for the road and
heavy trucks. The stone would be veneered tied if possible and the face of the
new wall would be constructed close enough to flow in a grout or mortar to
help tie the stone to the wall.
The owner prefers number 3 above as the
soldier piles would be very expensive for a 300-foot stretch of
There must be some other ideas out there. I thought we might be
able to work in a corrugated sheet "pile" idea and then tie it back to the
hillside bedrock using rock anchors.
Can anyone give me some ideas to
search out that might help me make an intelligent choice as to the most
economical solution to the problem?
Dennis S. Wish, PE
-- Dennis S.
Wish, PECalifornia Professional Engineer
(office - fax)
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