HomeMy WebLinkAboutCT 73-29; Carrillo Estates; Addendum to Update Soil; 1981-05-143467 Kuru Street
San Diego. Californta 921 10
Telex 697.841 714-224-2911
Woodwara-Clyde Consultants
May 14, 1981
Project No. 51142+U301
Ponderosa Rones, Inc. 11300 Sorrento Valley Road
San Diego, California 92121
Attention: Mr. Ken Cook
ADDEIJDUN TO
_CARRILL0 E
UPDATE INVESTIGATION
CARLSBAD, CALIFO-XVIA
Gentlemen:
i A sloj?e Stability analysis for a 1-1/2 to 1 (horizontal to vertical) fill slope along the proposed El Fuerte Street
extension of the subject site was inadvertently omitted from our update report of May 5, 1981. The fill slope is to be
approximately 30 feet in length and have a maximum height of
less than 20 feet.
The attached analysis was performed utilizing the Janbu nethod of analysis for deep-seated stability. The strength parameters are based on those given in our subject report, our work with similar formations in nearby areas, and our professional
judgment.
Our analysis indicates that the proposed slope has a calcu- lated factor of safety in excess of 1.5 for deep-seated
variations of soil strength parameters, however, there is stability under static conditions. Doe to the natural
still a finite probability that the slope could become un-
stable. In our opinion, the probability of the slope be-
coming unstable is low and it is our professional judgment
that it is reasonable to construct the slope as indicated above.
We recornmend that all slopes be properly constructed in
and that all s1,opes be drained, planted, and maintained accordance with the project plans and specifications,
to help control erosion and surface sloughing.
Ponderosa Homes, Inc.
May 14, 1981
Page 2 Project No. 51142W-UD01
(.' ' Wwdward-Clyde Consultants
Our experience indicates that slopes constructed at incli-
nations steeper than 2 to 1 are particularly susceptible to surficial sloughing in periods of rainfall, heavy
irrigation, or upslope surface runoff. Periodic slope maintenance, including rebuilding the outer 18 to 36 inches,
may be required. Sloughing of fill slopes can be reduced by overbuilding the slopes by at least 3 feet and cutting back
at maximum 4-fOOt fill height intervals. to desired slope. We recommend that fill slopes be backrolled
stability analysis, please give us a call.
If there are any questions concerning our additional slope
Very truly yours,
WOODWARD-CLYDE CONSULTANTS
Richard P. While
R.E. 21992
RPW/RJD/rs
Attachment
(4) Ponderosa Homes, Inc.
(4) Rick Engineering Company
Project No. 511".-.J-UDOl
CAiUILLO ESTATES
UNIT 2
FILL SLOPE
Assumptions:
(1) Maximum height of slopes H ' = 20 Zeet
(2) Plaximum slope inclination 1-1/2 to 1
(3) Unit weight of soil y = 120 pcf
(5 Apparent cohesion
(4) Apparent angle of internal friction 0 = 200
(6) No seepage forces.
c = 300 psf
References:
(1) Janbu, N., "Stability Analysis of Slopes with
Series No. 46, 1954.
Dimensionless Parameters," Harvard Soil Mechanics
(2) Janbu, N., "Dimensionless Parameters for Homogeneous Earth Slopes," JSMFD, No. SM6, November 1967. -
Analyses:
- Safety Factor, F.S. - - Ncf yH
C Where Ncf is the stability number for slopes with both c and $. -
From Fig. 10 of Reference (2) Ncf,= 13