HomeMy WebLinkAboutCT 05-12; Ocean Street Residences; RETAINING WALL CT 05-12; 2013-07-15AGS
ADVANCED GEOTECHISIICAL SOLUTIONS, INC.
9707 Waples Street, Suite 150
San Diego, Califomia 92121
Telephone: (619) 708-1649 Fax: (714) 409-3287
Zephyr Partners
11750 Sorrento Valley Road, Suite 130
San Diego, CA 92121
September 24,2013
P/W 1205-06
Report 1205-06-B-lOR
Attention: Mr. Jim McMenamin
Subject: Revised Response to City of Carlsbad Retaining WaU Review Comments,
Ocean Street Residences, City of Carlsbad, California
Gentlemen:
In accordance to your request Advanced Geotechnical Solutions, Inc. (AGS) has prepared this revised
response to the City of Carlsbad's redlines of the retaining wall submittal package for the proposed Ocean
Street Residences project retaining wall plans and design were prepared by Gouvis Engineering. This
response letter will supersede the previous letter (Report No. 1205-06-B-lO, (AGS 2013J)).
Item 1: SHEET 28 of 29, CMU Retaining Wall Details, DETAIL 7
COMMENT: "Specify gap, must accommodate maximum deflection of the retaining wall to avoid
damage to the buUding."
AGS RESPONSE: Using an active case for dense to loose sand, movement behind a 10 foot high
retaining wall is expected to be on the order of 0.1 inches to 0.5 inches respectively (see Figure 1.1 and
Table 1.1 from US Army Corps of Engineers 2001). Walls for which little or no movement can be
tolerated should be designed for at-rest lateral earth pressures. To further reduce the potential for wall
rotation a higher compaction standard (93% to 95% per ASTM Dl 557) can be used for the retaining wall
subgrade soils. Minimally this increased compaction standard would need to be a minimum depth equal
to the wall footing width. Additional measures should include select backfill with a sand equivalent SE >
30 extending a minimum of H/2 (where H=wall height) behind the wall and a minimum of 12-inches of
crushed rock (3/4 inch rock, wrapped in filter fabric Mirafi HON or equivalent) placed immediately
adjacent to the back of wall. The rock should extend to within 18-inches of design grade. Water proofing
will be a key element given the proximity of the building to the wall face and should be determined by the
Architect.
In general, given the granular soils and the aforementioned recommendations it should be assumed any
significant wall rotation will occur during the backfill operations. Accordingly, construction of the
proposed structures should not occur until the wall has been backfilled. This should minimize the
potential for damage to the structure as a result of wall deflection.
Item 2: SHEET 28 of 29. DETAIL 6 CALC
COMMENT 1: "Provide soils engineer approval of the design criteria used in this calc "
ORANGE AND L.A. COUNTIES
(714)786-5661
INLAND EMPIRE
(619) 708-1649
SAN DIEGO AND IMPERIAL COUNTIES
(619)850-3980
Page 2
Report 1205-06-B-l OR
September 24, 2013
P/W 1205-06
AGS RESPONSE: AGS has reviewed the proposed design criteria for the proposed flow through planter
walls. For the upper planter wall backfill areas where the water will collect in the bio-retention portion of
the wall backfill an equivalent fluid pressure of 62.4psCft should be used in the design of the walls.
Backfill below the bio-retention areas can utilize an equivalent fluid pressure of 35psf/ft. Water proofing
methods and materials for these and other walls onsite which should be determined by a waterproofing
consultant familiar with these types of bio-retention/wall systems.
Item 3: SHEET 28 of29. DETAIL 7 CALC
COMMENT: Evaluate maximum deflection of the retaining wall adjacent to the buildings. May
cause damage to the buUding structure."
AGS RESPONSE: See response to Item 1.
Advanced Geotechnical Solutions, Inc. appreciates the opportunity to provide you with geotechnical
consulting services and professional opinions. If you have any questions, please contact the undersigned
at (619) 708-1649.
Respectfully Submitted,
Advanced Geotechnical Solutions, Inc.
Dislribulion:
ident
xp. 6-30-15
(3) Addressee
(1) Dahlin (Jroup Attn.: Jonathan Shapero (email copy)
ADVANCED GEOTECHNICAL SOLUTIONS, INC.
Page 3 September 24,2013
Report 1205-06-B-1 OR P/W 1205-06
REFERENCES
Advanced Geotechnical Solutions, Inc. (20I3J). Geotechmcal Review of Proposed Ocean Street
Residences Liquefaction Mitigation and Response to Esgil Review Comments (Carlsbad PCJ3-0030),
City of Carlsbad, Califomia, P/W 1205-06, Report P/W 1205-06-B-lO, September24, 2013.
Advanced Geotechnical Solutions, Inc. (2013e). Geotechnical Review of Proposed Ocean Street
Residences Liquefaction Mitigation and Response to Esgil Review Comments (Carlsbad PC13-0030),
City of Carlsbad, California, P/W 1205-06, Report P/W 1205-06 B-8, July 16, 2013.
Advanced Geotechnical Solution.^, Inc. (2013d). Geotechnical Review of Structural Plans Ocean Street
Residences (CD 12-09), City of Carlsbad, California, P/W 1205-06, Report P/W1205-06-B-7, June
19. 2013.
Advanced Geotechnical Solutions, Inc. (2013c). Supplemental Geotechnical Recommendations Ocean
Street Residences (CD 12-09), City of Carlsbad, California, P/W 1205-06, Report P/Wl205-06-B-6,
May 22, 2013.
Advanced Geotechnical Solutions, Inc. (2013b). Preliminary Geotechnical Recommendations for
Permeable Pavers and "Grass Pave", Ocean Street Residences (CD 12-09), City of Carlsbad,
California, P/W1205-06. Report P/W1205-06-B-5, April 12, 2013.
Advanced Geotechnical Solutions, Inc. (2013a). Grading Plan Review, Ocean Street Residences (CD 12-
09), City of Carlsbad, California (CD 12-09), City of Carlsbad, California. P/W 1205-06, Report
P/W1205-06-B-3, March 19, 2013.
Advanced Geotechnical Solutions, Inc. (2012). Response to Cycle Review Comments Ocean Street
Residences (CD 12-09), City of Carlsbad. California, P/W 1205-06, Report P/W1205-06-B-2, October
30, 2012.
City of Carlsbad, Memorandum CDI 2-09-Ocean Street Residences 2"'' Review, dated October 25, 2012..
Esgil Corporation, Plan Check Review Comments, Multi Family Condominium Complex and Parking
Garage, 2303Ocean Street, Carlsbad Califorma. dated July 3, 2013.
Geocon Inc., Geotechnical Investigation, Ocean Street Condominiums, Ocean Street and Mountain View
Drive, Carlsbad, California, dated September 3, 2004 (project no. 07353-22-01).
Hayward Baker Geotechnical Construction, Inc. (HB 2013). Stone Column Construction Submittal Soil
Improvement Ocean Street Residences (CD 12-09), City of Carlsbad, California, July 15, 2013.
RBF Consulting, A Baker Company, Ocean Street Residences, Tentative Tract Map, dated October 8,
2012, Sheets I through 8.
US Army Corps of Engineers, State ofthe Practice in the De.ugn of Tall, Stiff, and Flexible Tieback
Retaining Walls, December 2001.
ADVANCED GEOTECHNICAL SOLUTIONS, INC.
us Army Corps
of Engineers®
Engineer Research and
Deveiopment Center
Innovations for Navigation Projects Research Program
State of the Practice in the Design of Tall,
Stiff, and Flexible Tieback Retaining Walls
Ralph W. Strom and Robert M. Ebeling December 2001
Approved for public release; distribution is unlimited. 20020822 012
level of prestress, soil presi5ures behind the wall in the region ofthe tieback
anchor can approach or possibly exceed at-rest pressure conditions.
An understanding ofthe interdependence between wall deformations and
earth pressures is fiindamental to the proper selection of earth pressures and earth
pressure distributions for the design of tieback wall systems. Ilie relationship
betweeti the movement of sand backfills and the static earth pressure forces
acting on the wall is shown in Figure 1.1. Ths figure is based on the data from
model retaining wall tests conducted by Terzaghi (1934,1936,1954) at the
Massachusetts Institute of Technology and tests by Johnson (1953) at Princeton
University under the direction of Tscliebotarioff. The backflll movements are
o 0.1
PRINCETON
TESTS MEDIUM
SAND
I I I
TERZAGHI
10
8
6
5
A
3
H 2
-LOOSE
SAND :
^2 rDENSE
ce
t/J W UJ QC
o.
tr <
I
0.8
0.6
0.5 0.4
0.3
LU <
<
li. o
o 0.2 .-
0.1
UJ o u
0.06 0.04
WALL ROTATION
0.02
tl
0 0.004
WALL ROTATION JL
PASSIVE CASE ACTIVE CASE
Figure 1.1. Relationship of earth pressure versus wall movements (after NAVFAC
DM 7.2,1982)
Chapter 1 Introduction
presented as the movement at the top of the wall (y) divided by the height of the
wall (H), and the earth pressure forces are expressed in terms of an equivalent
horizontal earth pressure coefficient (KH). Variable Knis equal to the horiz»ntal
effective stress (G'H) divided by the vertical effective stress (cfv). Other
investigations, both experimental and analytical (finite element method), have
been made to determine the wall movements needed to reach active and passive
limit state conditions. These investigations are summarized in Table 1.1, after
Clough and Duncan in Chapter 6 of Fang (1991).
Table 1.1
Approximate Magnitudes of Movements Required to Reach
Minimum Active and Maximum Passive Eartii Pressure Conditions
(adopted from Clough and Duncan 1991)
type of Backflll
Values of A/N'
type of Backflll Active Passive
Dense sand 0.001 0.01
Medium-dense sand 0.002 O.CB
Loose sarKl O.0O4 0.04
Compacted sitt 0.002 0.02
Compacted lean clay O.OlO' 0.05'
Compacted fat day 0.010= 0.06'
' Value of A Is aqua] to movement of top of wall required to reacti minimum active or maximum
passive pressure by lilting or lateral translation; H = haigtiX of wall.
Under stress conditions close to ttie minimum active or maxmum passive eartti pressures,
cohesive soils creep continually. Ttie movements stiown would produce active or passive pressures
onty temporarily. Wltti time, the movements will continue If pressures remain constant. If movement
nsmains constant, active pressures will increase wHh time, and passive pressures will decrease with
time.
Note that the magnitude of wall movement to fully mobilize the shear
resistance in the backfiU and thus develop minimum active or maximum passive
earth pressure conditions depends upon the soil type. For sands, the required
movements are distinguished by soil density. Loose sands require more wall
movement than do dense sands for the same wall height. Clough and Duncan
(1991) and Duncan, Clough, and Ebeling (1990) give the following easy-to-
remember guidelines for the amounts of movement required to reach the pressure
extremes in a cohesionless soil. The movement required to reach the minimum
active condition is no more than about 1 in. (25 mm) in 20 ft (6 m)
(AfH = 0.004), and the movement reqttired to reach the maximum passive
condition is no more than about 1 in. (25 mm) in 2 ft (0.6 m) (A/H = 0.04).
1.4.4 Construction short-term, construction long-term, and
postconstructlon conditions
During anchor wall construction there is a basic tendency for the wall and
soil retained by the anchored wall system to move toward the excavation as
excavation proceeds in front of the waU. When these movements are sufficient to
fully mobilize the shear resistance within the soil wedge within the retained soil,
the backfill is said to be in an active state of stress. The lateral stress exerted, for
Chapter 1 Introduction