HomeMy WebLinkAbout; Winslow Pacific Inc.; Soils Report; 1970-04-29.
SorL AND MATERIAL!~~TING LABORATORY
_~~. OF NORTH COUNTY. INC.
29 April 1970
Mr. James C. UJinslow
466 East Duarte Road Monrovia, California 91016
ENGINEERING DEPT. LIBRARY Re: Job No’. 70-48
City of Carl&ad Winslow Pacific Inc.
2075 Las Palmas Drive Por. Lot H, Ranch0 Agua
CaflsbaQ CA 92009-4859 Hedionda, Nlap 823
Carlsbad, California
Subject: Final Clearance on Controlled Fill and
Foundation Recommendations
Dear Mr. Ulinslow:
Enclosed are the test results and our findings concerning
the soil conditions for the above referenced project as you re-
quested. Prior to grading a visual inspection was made of the
subject site and it was concluded that the native soil was firm
and required only minimal preparation prior to placing fill.
As grading progressed,compection, bearing, and expansion tests
were performed upon which the included recommendations are based.
It is understood the site is intended to be developed for
several one story steel frama industrial buildings. The build-
ings will have perimeter wall footings with isolated piers to
support the column loads and concrete floor slabs. There will
be a parking lot in the northwest corner. The scope of our
work was to control the fill, the extent of which is shown on the
enclosed Site Plan, Plate 1. The location of one building had
been definitely established at the time of grading. Since this
building is in a cut area which contains expansive soils,
-
recommendations are included to minimize structural damage to,
the proposed building
The grading plan from which the enclosed Plate 1 ulas drawn
was prepared by the engineer of work, E. Brian Smith, RCE,
Oceanside. The approximate locations of fill placed under our
control and of field density tests are shomn on Plate 1. Also
shown are two areas of stockpiled soil which are uncontrolled
fills which should be excavated and recompacted if any structures
are planned for those areas.
The grading was done between the dates of 6 April 1970 and
20 April 1970.
The native ground was stripped of vegetation and top soil
prior to placement of any fill ground. There was no existing:
fill or unstable soils. The areas to receive fill were ripped,
6 inches, watered, and recompacted to at least 90% of the maxi-c
mum dry density. Sloped areas were also properly benched under
our supervision.
Field density tests were made in accordance with ASTM 01556-
64, the sand cone method, and are reported in the enclosure
entitled "Field Density Test Results". Tests were taken at least
every 2 foot gain in elevation and so spaced as to give the best
horizontal coverage. Areas of low compaction were brought to
the attention of the grading contractor, reworked, retested, and
proven to be compacted to a minimum of 90% of the maximum dry
density.
SOIL AND MATERIAL TESTING LABORATORY
OF NORTH ED”NTI.‘INC.
9
LABORATORY TESTS
1 - Compaction Tests
Four laboratory compaction tests were made to determine the
maximum dry density and optimum moisture content as specified
by ASTM D1557-64T (method A). This test uses the minus #4 sieve
soil in a 4 inch diameter 4 inch high cylindericel mold. The
sample is formed with a 10 pound hammer falling 18 inches for
25 blows on each of 5 layers. The results follow.
Soil Soil Max.Dry Optimum
Type Description Density, Moisture (pcf) Content (%)
1 Brown Silty Sandy Clay 120.0 12.3
2 Light Gray Clayey Sand 127.2 10.6
3 Gray Sandy Clay 116.0 12.8
4 Gray Silty Clay with White Streaks 114.7 13.8
2 - Expansion Tests
Four expansion tests were performed on the soil types, (one
each) described under “Compaction Tests” to determine if these
soils would constitute a structural hazard to the building with
respect to volumetric soil change. The tests were performed on
24 inch diameter 1 inch high ring samples. Three of the samples
which represent the fill were compacted to 90% of the maximum
dry density at optimum moisture content. The samples were loaded
with 1 psi, instrumented, air dried, and then submerged in dis-
tilled water until expansion stopped. The percent expansion is
recorded as the ratio of the final change in height to the initial
height. A similar test procedure was made on an undisturbed
sample of Soil Type 4, the material found in the cut area of the
proposed building.
SOIL ANII MATERIAL TRSTING LABORATORY OFNDRTH COUNTI. INC. 3
EXPANSION TESTS
Soil Initial Air Dry Saturated Expansion
Type Test * W W x W (%I
1 Remolded 110.1 13.0 112.0 1.7 95.4 24.4 17.4
2 Remolded 117.8 10.9 119.3 .4 116.2 14.1 2.8
3 Remolded 105.1 13.4 108.1 2.4 94.1 26.9 15.0
4 Undisturbed 101.6 23.2 101.6 4.9 86.9 29.8 16.9
*x: dry density (pcf)
w = moisture content ($)
3 - Direct Shear Test
A direct shear test was performed on the soil in the building
ares for strength parameters to be used in bearing capacity cal-
culations. Three specimens of the soil mere loaded with normal
loads of . 5, 1.0, and 1.5 K.S.F. respectfully and sheared to fail-
ure in the undrained condition. The results follow.
DIRECT SHEAR TEST
Soil Description Dry Angle of Apparent
Density Internal Cohesion
(pcf) Friction (psf) P
Gray Silty Clay with White Streaks 101.6 12 1600
The values of internal friction and apparent cohesion derived
from the direct shear tests were used in the Terzaqhi Formula in
accordance with the procedure outlined in Reference 1, page 170,
to compute the allowable bearing capacity.
Terzaghi Formula:
Bearing Capacity = ~/~cN'~+~D~N'~+~~BN;
SOIL AND MATERIAL TESTING LABORATORY
OF NDR7-” COUNT~.‘INC. *
Assumptions
Depth of Footing, Df = 2'
Width of Footing B = 1'
Nlc, N' q’ Nld = dimensionless parameters found from
Fig. 75, Ref. 1.
Factor of Safety = 3
Allowable Bearing Capacity = 3000
CONCLUSIONS AND RECOMMENDATIONS
1 - The results of our observations, field density tests,
and laboratory compaction tests indicate the compacted filled
ground has been placed at not less than. 90% of the maximum dry
density.
2 - The following recommendations are made for the proposed
building to be constructed on the expansive clay:
a - rip 6 to 8 inches of the native ground (a total of
at least 12 inches below the bottom of the slab), water lib-
erally, and roll lightly, to approximate soil consistency of
85% of maximum dry density at 3% over optimum moisture con-
tent,
b - place at least 6 inches of sand on top of this sur-
face and between the bottom of the slab,
c - reinforce the slab with wire mesh and place expan-
sion joints at least every 30 feet,
d - place the continuous footings two feet into the
ground below final grade and reinforce with two #4 reinforc-
ing rods - one rod within 4 inches of the bottom and one rod
within 2 inches of the top of the footing,
SOIL AND MATERIAL TESTING LABORATORY
q F NDRTH EOUNTI.‘INE.
5
e - place the isolated footings a minimum depth of
four feet into the ground,
f - use an admixture such as Red Label Suconem in
the floor slab to limit the flow of moisture.
3 - If our recommendations are followed, the footings may
be designed to withstand a bearing capacity of 3000 psf.
4 - Inspection by a qualified soil engineer should be made
of the trenches several days prior to casting the footings and
slab.
5 - The uncontrolled fill in the stockpile'areas should be
excavated end recompacted under the supervisionof a qualified
engineer if any construction is planned for these areas.
It is our understanding that the grading for this phase has
been completed. Our laboratory should be notified prior to any
future grading.
REFERENCE
1 - Terzaghi and Peck, Soil Mechanics in Enqineerinq Practice,
John Wiley, N. Y., 1948.
Respectfully submitted,
SOIL AND MATERIAL TESTING
LABORATORY OF NORTH COUNTY, INC.
Claude 6. Parker RCE 18,987
CBP:ec
Distribution: Addressee 6
SOIL AND MATERIAL TESTING LABORATORY
OF NORTHFmYNTY, INE.
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FIELD MNSITY TEST 5l-rE FUN
CDMWCTEDFIUAREA WINSIDW LFIC INC.
SOIL ANDY MATERIAL TESTItiG LABORATORY
or HO”,” ED”NTI, WE.
,
FIELD DENSITY TEST RESULTS
i-
Date Test Ht. of Field Field Max. Relative
of No. Fill Moisture Dry Dry Test Tested Content
1970 (Feet) %I
Density Density
,pcf pcf)
4-6
4-8
4-9
4-10
4-14,
..-
4-15
4-20
1 2.0 13.6 113.6 120.0
2 2.0 15.0 104.4 116.0
3 2.0 13.6 112.0 120.0
4 2.0 17.6 111.4 116.0
5 2.0 14.3 112.2 120.0
6 2.0 12.3 120.9 127.2
7 2.0 11.1 108.8 116.0
8 2.0 13.6 107.8 116.0
9 2.0 9.9 105.3 116.0
10 4.0 12.3 110.4 120.0
11 4.0 10.5 100.7 116.0
12 6.0 11.1 108.6 116.0
13 8.0 12.3 104.9 114.7
14" 4.0 9.3 103.8 114.7
15 2.0 12.3 108.7 120.0
16 6.0 13.6 108.0 116.0
17 4.0 11.1 110.9 116.0
18 10.0 9.9 116.5 127.2
19 4.0 11.1 108.9 120.0
20 6.0 10.5 109.3 120.0
21 8.0 12.3 109.5 116.0
22 10.0 12.3 107.9 116.0
23 12.0 11.7 113.3 116.0
24 4.0 13.6 109.3 120.0
25 F.G. 8.7 109.3 116.0
26 F.G. 9.9 116.7 120.0
27 F.G. 7.5 105.0 116.0
28 F.G. 10.5 110.1 120.0
29 F.G. 6.9 112.2 120.0
30 F.G. 11.7 114.8 120.0
31 F.G. 11.1 115.4 127.2
*14 q Re-Test of Test No. 11
:'-'-
F.C. = Finish Grade
See Site Plan for test locations.
94.6
90.2
93.4
96.0
93.4
95.1
93.8
92.8
90.7
91.8 I *
93.5
91.5 d.-- ,. '~ 90.6 ,
i,.~ 90.5
93.2
95.7
91.5
90.8
91.1
94.4
93.1
97.7
91.2
94.5
97.2
90.5
91.7
93.4
95.6
90.6
SOIL AND MATERIAL TESTING LABORATORY
OF NmRT” CDUNTI. INC. 7