HomeMy WebLinkAboutCT 82-04; PALOMAR OAKS II; RETAINING WALL DESIGN PARAMETERS; 1988-08-31SO U THERN CAL I F ORNI A SO IL A ND TES T ING , INC .
6280 RIVEROALE ST. SAN OIEGO, CALIF". 92120 • TELE 280·432 P.O. BOX 20627 SAN OIEGO. CALIF", 921 20
6 7 8 £NTC:RP R IS C: ST. ~ C'." O N D I O 0, C A L t r 9 2 0 2 ~
Augus .. 31, 1988
Birtcher Construction
27822 El Laza Road
Laguna Niguel, California 92656-3989
SCS&T 8821057
Report No . 3
SUBJECT: Retaining Wall Design Paraneters, West Oaks Way, Palomar Oaks II,
Carlsbad, California.
REF'EREICE: Suwlenentary Geotechnical Investigation, Palomar oaks II
Business Park, Southern California Soil and Testing, Inc., Report
No. 1, dated April 26, 1988.
Gentlenen:
In accordance with the request of Chris Christakos, Structural Engineer,
this report has been prepared to present retaining wall design paraneters
for the retaining wall planned along the southside of West oaks way. The
prop::,sed wall will have a height of about ten feet and will have a backslope
of about two horizontal to one vertical or flatter. The soils within a depth
of five feet of the fOWldation have been renoved and replaced as carpacted
fill. The backcut for the renoval operation exposed a stiff colluvium.
Based on our observations and grading recormerx:lations, it is our opinion
that the unrestrained cantilever retaining wall should be designed with an
active soil pressure of 53 powxis per cubic f oot. The wall should have
sufficient weep holes and gravel behind the wall to prevent hydrostatic
pressure build-up. The gravel drain should be at least 12 inches wide am
should extend to within two feet of the ground surface at the top of the
SOUTHERN CALIFORN I A S O IL AND TEST I NG, I N C .
SCS&T 8821057 Augus t 31, 1988 Page 2
wall. The gravel should be separated from t he adjacent soil by a Geofabric
Filter material.
The foundation for the retaining wall may be designed using an maxim.mt
allowable soil bearing pressure of 4000 pounds per square foot. The
coefficient of friction bet~n the concrete footing and soil may be taken
as O. 35. A passive pressure against the side of the footing and key can be
assuned to be 350 p:Junds per square f(X)t per foot of depth. The friction and
passive resistance may be conbined, however, when doing so, the friction
value should be reduced by one-third.
All backfill for the retaining wall should be nonexpansive and should be
coopacted to at least 90 percent relative corrpaction.
If you should have any questions after reviewing this rep:Jrt, please do not
hesitate to contact this office.
This ORX)rtunity to be of professional service is sincerely awreciated.
Respectfully sul::mitted,
SCUIHERN CALIFORNIA SOIL & TESTI~, IOC.
4fl<L.ltdt:r
Charles H. Christian, R.G.E. #00215
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cc: (3) Sul::mitted
(3) Chris Christakos Engineering