HomeMy WebLinkAboutCT 74-04; QUAIL RIDGE; SLOPE STABILITY ANALYSIS; 1977-11-02'~~ "
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GEOeON
INCORPORATED ENGINEERS AND GEOLOGISTS' CONSUI,.TANTS IN THE APPLIED EARTH SCIENCES
File No. D-0684-M01
November ?, 1977
Standard Pacific of San Diego
7906 Convoy Court
San Diego, California 92'111
RECEIVED
, NOV 031977
Attention: Mr. Dave Phares CITY OF CARLSBAD
Subject: . Engineering Department Carlsbad Tract No. 74-4 (Quail R~dge) ,
Carlsbad, California
SLOPE STABILITY ANALYSIS
Gentlemen:
At: the requeSt of the proj ect engineer, Mr,. Alex Pantich,
we have reviewed the project grading plans, and our Novem-
ber 5, 1976 report 'of Soil and Geologic Investigation. The
purpose of our review and slope stability analysis was to
determine if the proposed slopes shown on the grading plans
possess an adequate factor of safety against deep-seated
rotational failure.
The majority of cut and :till ,slopes on the project over
30 feet in height will be constructed with benches. Those
fill slopes that will not be constructed with benches range
from a 65 foot high 2.0 horizontal to 1.0 vertical s'lope to
a 60 foot high 1.5 horizontal to 1.0 vertical slope.'
Utilizing strength criteria as presented in our referenced
soil and geologic investigation and the slope design chart
p~esented by Singh (1970, Figure 1, attached), we have de-
termined that a 60 foot high 1.5 horizontal to 1.0 vertical
fill slope will have a factor of safety of approximately
1. 8. The fa'ctor of safety for a 2..0 horizontal to 1. 0 ,
vertical fill slope 65 fee,t in height; based on the same',
series of charts, would be 2.0. '
The above factors of safety as'Sume static loading condi-
tions and straight slopes (no benches). Benches are not
• 6645 CONVOY COURT' SAN DIEGO, CALIFORNIA 92111 • PHONE (714) 292-5100
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File No. D-0684-MOl
November 2, 1977
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required to obtain the required slope stability. The cal-
culated factors of safety should be.reduced by approximately
0.4 if a seismic load of O.lg is applied.
Very truly yours,
GEOCON, INCORPORATED
T~?(1.u
RCE 20427
MWH:lr
copies: (1) addressee
(4) Alex Pantich
Rick Engineering, Carlsbad
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GEOeON
INCORPORATE])-
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File No. D-~-M01
November 2, 1iJ77
0", 1--+--+--1--1--4--1 A-• 1.5
"" GIVIN c ANa ; Of ISOIL.'.o r 'NO H o,41--i-''i-+-4Of THE SLOPE PLOT POINT c'rH, -.
"" ANO fAD FjTOft OF SAfET'r. I
10 20 30 ;, O£GIIEE. 40
FIG. ll.-F-CONTOURS FOR SLOPE
1-1/2:1
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GIVIN • ANa • Of ~IL''.o r .NO H O,41--'k,~-t--+Of THE 'LOI'E PLOT POINT ClrH, ;
'\ 'NO ,£A1) fACTOII Of S~rETY. I
FIG. 12 ...... F-CONTOtlttS F,OR SLOPE 2:1
After Singh, A., 1970, Shear Strength and
Stability of Man-Made Slopes, Journal Soil
Mechanics and Foundations Division, A.S.C.E.,
Vol. 96, No. SM6, p. 1879-1892
Soil Strength Parameters
(/) = 35.0
C -350
Dry Density -115.2 pcf
SLOPE STABILIl'Y DIAGRAMS
CARLSBAD TRACT NO. 74-4
Carlsbad, California
FIGURE N!
1 GEOCON t INCORPORATED
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GEOeON
INCORPORATED