Report (56) 7 k7 \ - oo01C1 5\,Ci r .
C EOPIERFF COPY Geopier Northwest
40 Lake Bellevue,Suite 100
Bellevue,Washington 98005
Tel. 425.646.2995-Fax 425.646.3118
www.geopier.com
August 6, 2018
TO: Mr. Anders Otterlei
Hill Architects
SUBJECT: Design Submittal
Geopier Ground Improvement
72nd Ave Apartments—Tigard, OR
Dear Mr. Otterlei:
This letter and the attached documents represent our design submittal for Geopier® soil
reinforcement at the site of the planned 72nd Ave Apartments development located in Tigard, OR.
The following paragraphs document our design of the patented Geopier-Impact reinforcement
system for support of spread and continuous foundations.
Geopier Reinforcement Design
Subsurface information, as documented in the geotechnical report prepared by GeoPacific, Inc.,
was utilized for our design. The subsurface conditions below the existing grades consist of 10
feet of stiff to very stiff clay, underlain by 20 to 25 feet of soft to stiff silt, then by very stiff elastic
silt. Groundwater was encountered at a depth of 12 to 15 feet.
In view of the soft cohesive soils across the site coupled with a high groundwater table, the
Geopier-Impact system or "displacement process" will be used. The Geopier-Impact system
which we propose to utilize consists of a hollow mandrel with an internal compaction surface
which is driven into the ground using a powerful static down force augmented by dynamic vertical
impact energy. After driving to the design depth, the hollow mandrel serves as a conduit for
aggregate placement. As the mandrel is raised and redriven downward thin lifts of compacted
aggregate are formed and compacted both vertically and laterally. The process is repeated until
the rammed aggregate pier is constructed. Also, the risk of casing is eliminated and our system
does not utilize messy and disturbing methods of water and air jetting to advance our Geopier
mandrel.
Our Geopier elements will be installed directly beneath all footings and are designed utilizing a
Geopier cell capacity of approximately 50 kips. Our design has utilized the loading information
provided by the structural engineer for our design which provides up to an allowable 4,000 psf
bearing capacity, which can be increased by 1/3 for short duration loading. The Geopier
elements will be installed to 25 feet or refusal, whichever is reached first. Practical refusal is
considered less than 1 foot of mandrel advancement in 30 seconds. In addition to foundation
support and slab support, a row of confining Geopier elements will also be installed encircling the
building, where space permits. Our ground improvement solution (approximately 275 Geopier
elements to 25 feet) will mitigate lateral spread and liquefaction settlements of the soils on-site,
but we are not responsible for liquefaction and lateral spread of soil between the site and site
wall across the street and subsequent damage that may occur to the structure. The Geopier
system is designed to limit differential seismic settlements to less than 2 inches over 30 feet.
Geopier"and Rammed Aggregate Pier'are registered trademarks of Geopier Foundation Company,Inc.
72nd Ave Apartments August 6, 2018
Tigard, OR Page 2
Settlement
For our analysis, settlements are first calculated for a zone extending from the bottom of the
footing to the depth of the reinforcement. The weighted modulus method (Bowles 1988) is used
to estimate settlement in the reinforced zone. This method is described in the Geotechnical
Engineering Division/ASCE publication "Control of Settlement and Uplift of Structures Using
Short Aggregate Piers) by Dr. Evert C. Lawton, Dr. Nathanial Fox, and Dr. Richard L. Handy.
Additional settlement may occur in the "lower zone" or in the unimproved soil beneath the
reinforced zone. The lower zone settlement is calculated using an elastic approach. We
estimate that total settlement (static)will be less than one inch. Differential settlement most likely
will be less than one-half inch. Please see our attached calculations for additional information.
Geopier Installation
The installation of the Geopier reinforcement will be completed in accordance with the attached
specifications. The installation will be conducted under the supervision of an experienced
geotechnical engineer from Geopier Northwest, Inc.
We appreciate the opportunity to work with you on this project. If you have any questions or
require further information, please call.
Sincerely,
Geopier Northwest Inc. i .tiO PROr
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Attachments: Geopier Foundation Plan and Construction Notes and Geopier Calculations
GEOPIER® Foundation Company GEOPIER ®
Project:72nd Ave Apartments
No.:
Engnr:DVT SQUARE FOOTINGS
Date: Version 3.0.6 August 2013
INPUT PARAMETER VALUES: _ TOP OF PIER STRESS-SQUARE FOOTINGS
(Parameter Symb I Val.I 'Parameter I Symb lEquation 1F4 (F5 1F6 IF7 1E8 .1
'RAP diameter(in) d 221 Column load(kips) P ... 50 100 156 200 2 0
Depth to groundwater(ft) dgw 4 Requited footing width(ft) Br sqrt(P/qaf) 3.54 5.00 8.12 7.07 7.91
.Total unit weight of soil(pcf) g 120 Selected footing width(ft) B 4 5 6 7 9
-Soil frill.angle(degr) f 26 Footing bearing pressure q P/(B'B) 3.13 4.00 4.17 4.08 3.09
Max.hor.pressure(OM) pmax 2500 Required No.RAP elems Nr P/Qcall 1.0 2.0 3.0 4.0 5.0
From Table 4.2: Selected No.RAP elems N 1 2 3 4 5
RAP cell cap.(kips) Qcell 50 Area replacement ratio Ra N•Agl(813) 0.165 0.211 0.220 0.215 0.163
Footing bearing press.(kat) pat 4 Stiffness ratio Rs kg/km 9.0 9.0 9.0 9.0 9.0
RAP stiffn.modulus(pci) kg 180 Stress at top of GP(ksf) qg q"Rs/(Rs•Ra-Ra+1) 12.12 13.39 13.59 13.49 12.06
Soil stiffness modulus(pc) km 20 Load at toot GP(kips) Qg gg•Ag 32.0 35.3 35.9 35.6 31.8
SHAFT LENGTH REQUIREMENTS
Depth of Embedment DI 2.0 2.0 2.0 2.0 2.0
Trial shaft length(ft) Hs 23.0 23..0 23.0 23.0 23.0
Drill depth(ft) Hdrill Df+Hs 25 25 25 25 25
Frictional resistance force(kips) Qs fs'pi•d•Hs 137 137 137 137 137
Allowable tensile resistance(kips'Osalt Qs/2 69 69 69 69 69
Allowable end-bearing rest.(kips)Qeb Qeb 0 0 0 0 0
Is shaft long enough? Qs+Qeb,Pcdem? ok ok ok ok ok
INPUT PARAMETER VALUES: UPPER ZONE SETTLEMENT-SQUARE FOOTINGS
Upper Zone Elastic Parameters Parameter Symb Equation
Parameter ISym Val UZ Settlement Approach 1-Stiffness,2-Modulus 2 2 2 2 2 2 2
'Pier Modulus Layer 1(ksf) Egl 2500 Thickness of UZ sublayer 1(ft) H,m, 5.0 5.0 5.0 5.0 5.0
Pier Modulus Layer 2(ksf) Egg 2500 Thickness of UZ sublayer 2(ft) I-L 4.0 4.0 4.0 4.0 4.0
fI Pier Modulus Layer 3(ksf) Eg3 1400 Thickness of UZ sublayer 3(ft) Hmes 5.0 5.0 5.0 5.0 5.0
I Pier Modulus Layer 4(ksf) Eg4 1400 Thickness of UZ sublayer 4(ft) ti,. 5.0 5.0 5.0 5.0 5.0
Pier Modulus Layer 5(ksf) Eg5 1400' Thickness of UZ sublayer 5(ft) H. 6.0 6.0 6.0 6.0 6.0
Soil Modulus Layer 1(kat) Em1 200. Total UZ Thickness OK? Huz=Hs+d ok ok ok ok ok
Soil Modulus Layer 2(ksf) Em2 200• Composite Modulus Layer 1(ksf) E,,,,,,p, Eg1 Ra+Em1(1-Ra) 579 686 706 896 575
Soil Modulus Layer 3(ksf) Em3 75 . Composite Modulus Layer 2(ksf) E,,,,,2 Eg2Ra+Em2(1-Ra) 579 686 706 696 575
Soil Modulus Layer 4(ksf) Em4 75 Composite Modulus Layer 3(kat) F.,„,ps Eg3Ra+Em3(1-Ra) 294 355 366 361 291
Soil Modulus Layer 5(ksf) Em5 75 Composite Modulus Layer 4(list) Emma Eg4Ra+Em4(1-Ra) 294 355 386 361 291
Composite Nodulus Layer 5(ksf) E,,,,as Eg5Ra+Em5(1-Ra) 294 355 366 381 291
Sett.of L2 sublayer 1(in) s., %NV w qlo-vaa i Ecomp 0.20 0.24 0.27 0.29 0.28
Sett.of LZ sublayer 2(m) s.2 q7 a-2•H„,JE,,,,p2 0.04 0.06 0.08 0.09 0.12
Sett.of LZ sublayer 3(in) %a q9 o-3i4 SEv,,,,,3 0.04 0.08 0.08 0.10 0.15
Sett.of LZ sublayer 4(in) s..4 q•lo-41H4,01E,,,„o 0.02 0.03 0.04 0.05 0.08
Sett.of 12 sublayer 5(in) sues q•la3•H,,srE,,,,,,,, 0.01 0.02 0.03 0.04 0.06
(Total Upper Zone Settlement(in)I s,m I s,a,+3,2+s,a,+s„„+5,as 1 0.30 I 0.41 I 0.50 10.58 I 0.69 I '
INPUT PARAMETER VALUES: LOWER ZONE SETTLEMENTS-SQUARE FOOTINGS
Parameter - I Symb I Val' 'Parameter CSymb Equation IF4 IF5 IFE IF7 F8 1 I
Allowable end-bearing(kips) Qeb Dpth to bottm of LZ from fig(ft) X'B X•B 8 10 12 14 18
E or c.for L2 sublyr 1 E,/c,,, Upper zone thickness(ft) H,II Hs+d
1E or c for LZ sublyr 2 %I C.' ' Lower zone thickness(ft) Ha H2b-Hlz r
E or c,for LZ sublyr 3 E4/ca : Thickness of LZ sublayer 1(ft) H.
E or S:for LZ sublyr 4 E./c. I Thickness of LZ sublayer 2(ft) H.
E or c for LZ sublyr 5 Es/cc • [Thickness of LZ sublayer 3(ft) H.
Calc.settlement to X•B X 2 ; Thickness of LZ sublayer 4(ft) Hr.
Thickness of LZ sublayer 5(ft) Hss
Total LZ thickness ok? No LZ No LZ No LZ No LZ No L2
E or c for 12 sublyr 1 E1/c1 E(ksf)or c r r ( . r
E or c for LZ sublyr 2 E_/c2 E(ksf)or c e r r e r
I E or c,for LZ sublyr 3 Es f c,s E(ksf)or P. r r r . r
Eorcfor LZsublyr 4 E./c. E(ksf)orc r r 0 r e
E or c for LZ sublyr 5 Es/ca E(ksf)or c 0 e r r
Initial stress for sublyr 1(list) P., 1.795 1.795 1.795 1.795 1.795
Initial stress for sublyr 2(kW) P. 1.795 1.795
Initial stress for sublyr 3(list) P,a 1.795 1.705 1.795 1.795 1.795
Initial stress for sublyr 4(list) P,. 1.795 1.795 1.79.5 1.795 1.795
Initial stress for sublyr 5(kW) P,s 1.795 1.795 1.795 1.795 1.795
Ftg stress on sublyr 1(ksf) AP1 q•1 0.06 0.08 0.11 0.15 0.18
Ftg stress on sublyr 2(ksf) AP2 el 0.06 0.08 0.11 0.15 0.16
Ftg stress on sublyr 3(ksf) 8P3 q•I 0.06 0.08 0.11 0.15 0.18
Ftg stress on sublyr 4(ksf) AP4 q•1 0.06 0.08 0.11 0.15 0.18
Ftg stress on sublyr 5(ksf) APS p1 0.08 0.08 0.11 0.15 0.18
Sett.0112 sublayer 1(in) sr, wrHrilo((PP1.DPtyPoi) 0.00 0.00 0.00 0.00 0.00
Sett.of 12 sublayer 2(in) s1a eo21Hm•14((w62.oP2)/w.2) 0.00 0.00 0.00 0.00 0.00
Sett.of LZ sublayer 3(in) s® e -s3•xa(ma+•oesyeon 0.00 0.00 0.00 0.00 0.00
Sett.of LZ sublayer 4(m) sr. wear.l®lw.op.)mo.) 0.00 0.00 0.00 0.00 0.00
Sett.of LZ sublayer 5(in) sss ,os•Hrs•wq(ros.cws).a>s) 0.00 0.00 0.00 0.00 0.00
Total lower zone sett.(in) ss sr,+ss2+sm+sr,+sas 0.0 0.0 0.0 0.0 0.0
(Total UZ+12 settlement(in), I sI I 0.3 I 0.4 I 0.5 1 0.6 I 0.7 1 I
Note:When"No L2"is displayed,thicknesses of lower zone should equal 0
pg1 of