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Home My WebLink About; ; Geotechnical Parameters Carlsbad Boulevard Overhead Bridge 573-134 Seismic Retrofit; 2001-03-05I !DELTA: CONSULTANTS March 5, 2001 Simon Wong Engineering 9968 Hilbert Street, Suite 202 San Diego, CA 92131 Attention: Mr. Mark Creveling I Ccrtifird MBE Subject: Recommended Geotechnical Parameters Carlsbad Boulevard Overhead (Bridge No. 57C-134) Seismic Retrofit Project I f11r•1rimm,·11/,1/ t.P1s111,wiug Dear Mark: San Diego County, California Group Delta Project No. 1-147 In response to your request, we are pleased to provide you our recommendations regarding the seismic retrofit design of the existing Carlsbad Boulevard Overhead Bridge. The bridge is located along Carlsbad Boulevard approximately 0.6 mile northwesterly of Elm Avenue (see Figure 1). Review of Existing Data We have reviewed the Preliminary Geotechnical Report dated May 23, 1997 and the Liquefaction Report dated August 12, 1997 prepared by Group Delta Consultants (GDC) as part of the Local Agency Seismic Retrofit Project. There was no Log of Test Borings (LOTB) available for the bridge. GDC performed two hollow-stem auger borings (BH-1 and BH-2) on June 6, 1997 to investigate liquefaction potential at the bridge site. The boring logs and laboratory test data are provided in Appendix A. The Boring Location Plan is shown in Figure A-1 in Appendix A. Subsurface Conditions Based on the results of field investigation by GDC, soils at the bridge site consist mostly of clayey sand to sandy clay (SO'CL) fill soils, overlying terrace deposits consisting of dense to very dense silty to clayey sands (SM/SC) and poorly graded sand (SP). A clayey sandstone bedrock (Santiago Formation) was encountered below the fill and terrace deposits at about El. + 24 ft in boring BH-1 and El. + 14 ft in boring BH-2. A soil cross-section below the bridge is shown in Figure 2. Groundwater was not encountered in boring BH-1. A perched groundwater was encountered in boring BH-2 at El. + 14.5 feet. 92 Argonaut, Suite 120 A Aliso Viejo, California 92656-4121 A (949) 609-1020 voice A (949) 609-1030 fax Torr,11ic1', C1liforni,1 A (11fl) 1~1l-"il(\(l S,1n Diego, C0liforni,1 A (8S8) 'iT"\-1777 www.(;rou~)!Jelta.1.:om I I I Recommended Geotechnical Parameters Carlsbad Blvd. Overhead Simon Wong Engineering GDC Project No. 1-147 Recommended Soil Parameters AprilS,2001 Page 2 At your request we are providing soil parameters for each major soil type encountered. The soil parameters include unit weight (y), friction angle ((j>), cohesion (c), soil modulus (k), and strain at 50% of ultimate stress (&50). In addition, we are also providing ultimate and allowable bearing capacities and coefficient of friction. The recommended geotechnical parameters are summarized in Table 1. References Group Delta Consultants, 1997, "Preliminary Geotechnical Report, Local Agency Seismic Retrofit Project, Bridge No. 57C-134, Carlsbad Overhead, San Diego County, California," prepared for Moffatt & Nichol Engineers, dated May 23, 1997. Group Delta Consultants, 1997, "Liquefaction Report, Carlsbad Overhead, Bridge No. 57C-134, Local Agency Seismic Retrofit Project, San Diego County, California," prepared for Moffatt & Nichol Engineers, dated August 12, 1997. Attachments The following table, figures and appendix are attached and complete this letter report: Table 1 Figure 1 Figure 2 Appendix A Summary of Recommended Geotechnical Parameters Site Location Map Soil Cross Section Existing Geotechnical Data 1147-Rercommended Geotechnical Parameters.doc I I I I IGROUP !?1 DELTA ttMii■ihi:f Recommended Geotechnical Parameters Carlsbad Blvd. Overhead Simon Wong Engineering GDC Project No. 1-147 April 5, 2001 Page 3 We hope this report meets your immediate needs. We appreciate the opportunity to assist you in this important project. If you have any questions, please call us at (949) 609-1020. Very truly yours, GROUP DEL TA CONSULTANTS, INC. J~i&?,. Project Engineer t/r / 2n I 1147-Rercommended Geotechnical Parameters.doc Ku! Bhushan, Ph.D., _.,;G;,;;.E;;..·,..,,,...._ President E 000144 \ 12/31/01 : 'V 1 ,\\c,'t-~ TEC\\'° {I.-~ Fcr,..0:~ -· I I Soil 'Y Type (psf) Fill 120 Terrace 125 Deposits Bedrock 130 ~ --~~i~~iJ TABLE 1 SUMMARY OF RECOMMENDED GEOTECHNICAL PARAMETERS CARLSBAD BOULEVARD OVERHEAD (BRIDGE NO. 57C-134) SEISMIC RETROAT PROJECT ♦ C k F.so Ciltimate Bearing Capacity (deA,) (pst) (pci) Ck.st) 0 2,000 500 0.01 10 38 0 225 N/A 25 0 5,000 2,000 0.005 25 AUowable Friction Bearing Coefficient Capacity (ksf) 3 0.35 5 0.50 5 0.50 I I I I I I I .. • 1 PROJECT SITE Bridge No. 57C-134 l..=lli!l~ .. ,, The.Base Map is from the USGS 7.5 minute San Luis Rey, California Quadrangle, 1968, Photorevised 197 5 GRO ?i DF.l ,. ' \ \ ~ l " ~ ·l-~ \ t." l· . ';_ I ·l""U C· \' . ~ ,-► . . . ..: ~<: A Approx. Scale 1:24000 PROJECT NO. 1-14 7 Site Location Map Carlsbad Overhead FIGURE 1 r i,. l i· ( r l I .I. \ l \. .y I I I I ----1-<1--n-. I ); .5CAt..E': \ 11= 20FT FIGURE2 •,. ' I n> t(JJ' ANGCr:i:.s- lttl/w: p~ ,-.,,11.11~ n~ . 0-&.k ,-,;,., -,.,11 ~ -,o/"~"d,,qj,f""<1'<· . XJ-S.0-C~-"Rd * 51-C-134 sr.,urorcALt~IIA CA.l.ll"?Ya'WA lt.GYWAY alV.11/S&OV BRIIJG£·- . 0'4"' Th.I; 1 ~TDo/lSOV 7VR:7(A U SAN7A FE 1.t:?Y. NaR CARLSBAD-STA.. 476,..3069 8.1W q,a;o COllNTY 0£N~PLAN S'CA.'-:-£--fl,KJf--0"' . I -J I I I ' J APPENDIXA EXISTING GEOTECHNICAL DATA I I I APPENDIX A A. l Introduction The subsurface conditions at the project site were investigated by Group Delta Consultants on June 6, 1997 by performing two soil borings shown in Figure A-1, Boring Location Plan. A summary of the soil borings is presented in Table A-1. The results of field investigation and laboratory testing are summarized in Table A-2. A.2 Field Investigation The borings were advanced utilizing a CME 95 hollow-stem drill rig. The borings had a hole diameter of about 8 inches. The borings were performed by West Hazmat Company under a continuous technical supervision of a Group Delta representative, who visually inspected the soil samples, maintained detailed logs of the borings, interpreted stratigraphy, classified the soils, and obtained split-spoon Standard Penetration Test (SPT) samples at 5 ft interval. The soils were classified in the field and further examined in the laboratory in accordance with the Unified Soil Classification System (Figure A-3). Field classifications were modified, where necessary, on the basis of laboratory test results. Soil samples were obtained using Standard Penetration Tests which were performed in accordance with ASTM Dl586-82 using a 2-inch outside diameter and 1.375-inch inside diameter split-spoon barrel sampler. The SPT sampler was driven with a 140-pound safety hammer dropping 30 inches. The Standard Penetration Test consists of counting the number of hammer blows it takes to drive the sampler 1 foot into the ground. SPT blowcounts are often used as an index of the relative density and resistance of the sampled materials. A.3 Laboratory Testing Soil samples were carefully sealed in the field to prevent moisture loss. All the samples were then transported to our laboratory for examination and testing. Tests were performed on selected samples as an aid in classifying the soils and to evaluate their physical properties and engineering characteristics. All tests were performed in general accordance with appropriate Caltrans Testing Methods (CTM). Brief descriptions of the laboratory testing program and test results are presented below. A.3.1 Soil Classification The subsurface materials were classified using the Unified Soil Classification System, in accordance with ASTM Test Methods D2487-85 and D2488-84. The soil classifications I I I are presented on the boring logs in Appendix A and summarized in Table A-2. A.3.2 In Situ Moisture Content Moisture content and dry density were determined for selected samples. The drive samples were trimmed to obtain volume and wet weight then were dried in accordance with CTM 226. After drying, the weight of each sample was measured, and moisture content and dry density were calculated. The moisture content of selected SPT samples and bulk samples were also determined. Moisture content values are presented on the boring logs in Appendix A and summarized in Table A-2. A.3.3 Grain Size Distribution and Wash Analysis Representative samples were dried, weighed, soaked in water until individual soil particles were separated, and then washed on the #200 sieve. The portion of the material retained on the #200 sieve was oven-dried and then run through a standard set of sieves in accordance with CTM 202. The results of grain size distribution tests performed are graphically shown in Figure A-2. The relative proportion (or percentage) by weight of gravel, sand and fines (silt and clay) are determined from Figure A-2 and summarized in Table A-2. The percentage of fines (i.e., soil passing #200 sieve) is an important factor for evaluating the liquefaction potential of sandy soils. Fines content were determined for selected sandy soil samples which may liquefy. The results are presented in Table A-2. A.4 Boring Logs Detailed logs of the soil borings including blowcount data and in situ moisture content and dry densities are presented in Figures A-4 through A-5. Laboratory tests performed other than the moisture content and dry density determination are shown on the boring logs in the column "Other Tests". The following abbreviations are used on the logs to indicate the type of test performed. GS Grain Size Distribution Test WA Wash Analysis/ Fines Content Determination(% Passing #200 Sieve) A.5 List of Attached Tables and Figures The following tables and figures are attached and complete this appendix: Table A-1 TableA-2 Figure A-1 Figure A-2 Figure A-3 Figures A-4 through A-6 Soil Boring Summary Summary of Field and Laboratory Test Results Boring Location Plan Grain Size Distribution Key for Soil Classification Boring Logs (BH-1 through BH-2) Boring Station No. No. BH-1 477+70 BH-2 48o+I3 Notes: • Groundwater not encountered • * Perched groundwater encountered TABLEA-1 SOIL BORING SUMMARY CARLSBAD OVERHEAD (BRIDGE NO. 57C-134) LOCAL AGENCY SEISMIC RETROFIT PROJECT Offset from Surface Total Groundwater Centerline Elevation Depth Depth (ft) (ft) (ft) (ft) 28.0LT 49.0 30.5 * 48.7LT 39.0 46.0 24.5 ** Associated Excavation Foundation Equipment Support Bent6 CME75 Bent I CME75 I I I I l Boring No. BH-1 BH-2 Sample Depth (ft) 5-6.5 * l 0-1 l.5 15-16.5 20-21.5 25-26.5 30-30.5 l-2 * 5-6.5 10-1 l.5 15-16.5 20-21.5 25-26.5 30-31.5 35-36.5 40-41.5 45-46 * Note: TABLEA-2 SUMMARY OF FIELD AND LADORA TORY TEST RESULTS CARLSBAD OVERHEAD (BRIDGE NO. 57C-134) LOCAL AGENCY SEISMIC RETROFIT PROJECT uses Equiv. SPT Moisture Dry Gravel Sand Fines Soil Blowcount Content Density Content Content Content Type (blows/ft) (%) (pcf) (%) (%) (%) CL 16 CL 26 18.3 109.6 SC 33 10.7 33.8 SC 16 10.5 21.5 SC >100 9.8 120.4 SC > 100 11.l SC 43 SC 32 6.3 29.1 SM/SC 37 5.7 0 76.5 23.4 SM/SC 45 5.6 16.0 SP 81 8.0 0 90.1 9.9 SC 86 6.9 19.6 SC 73 11.0 SC 71 12.7 30.5 SC 71 11.1 SC 87 • No sample recovery Liquid Plastic Limit Limit (%) (%) ' I I, I I t, UNIFIED SOIL CLASSIFICATION COBBLES GRAVEL SAND COARSE I FlNE COARSq MEDIUM I FINE U.S. SIEVE SIZE IN INCHES U.S. STANDARD SIEVE No. 12 6 S S/4 1/2 S/6 4 10 20 40 60 140 200 100 - 9 \ ~ 80 ~ -[; >- ~ :\ v, ) p::i 60 t!, ~ \~ 00 00 a: ~ 40 la::l t..) p:: ~ \ \ p.. \ " ~) 20 l \ ~ I 10 2 ' I l 10 1 10-1 GRAIN SIZE IN MILLIMETER SILT OR CLAY HYDROMETER -, l 1Cf2 0 20 40 60 80 100 10-3 E-< :::c: t!, ..... ~ >-< p::i Q rzl z ~ la::l ~ e-, z ~ CJ p:: r.::I p.. SYMBOL BORING ~tfH ..Mi_ A=n=Es=c=RIP=.;;...aTI=O=N;.;..._ _____________ _ 0 BH-2 □ BH-2 Remark : Project No. 1-111 10-11.5 20-21.5 SM/SC SP CARLSBAD OVERHEAD 'l 1 GROUP DELTA GRAIN SIZE DISTRIBUTION Figure No. A-2 ,,.! CONSULTANTS, INC. 1 ;J I ' 60 g X 40 .g .s i J 20 6:: I GROUP PRIMARY DIVISIONS SECONDARY DIVISIONS SYMBOt. '6 .a OLEAN GW W.UGR&ded Gravell, Gravels Wlh Send, UIII or No Fina•. ~ii!f GRAVELS :-a l (l.e.ss Than 5" GP Poorty Gtadld Gravels. Gravels Wlh Sand. Ude or No Flnet. @J ~jl: .. ~ FI/JIIS < l~ GM aS~ ffi~! ~ GRAVEL SIity Gravels, Slty Gravel WIUl Sand, Non Pfaatlo Anes. ~ -a a :t~ Mom Than 12" ~It i FJnssJ GC Clayey Gravell, Clayey Gravel WIUl Sand. Pasllc Anes. G!!~ 'a .tl. Cl.£.ANSANOS SW Well Gl"Bdod Sands, Sand Wllh GravaL Ulla or No Fklea, w -!:l~ ~i Ce (Less Than 5" ~e cn:i: ~~ F1n11s) SP Poorly Graded Sands, Ullla or NQ Flnas. <~ ~ a! I!.._ i;i 8 ~ ~,~ SANOS SM saty Sandt, Sand-SIil MIXturas. NOfloPlasllc Fhes. rnefll)~ (MMJ Than I ~ c3 Fines) SC Clayey Sands, Sand-Clay Mll<lures. Plaallc Fines. -. lnOrganlc SIila and Vert AM Senda, RQck AJur, SUly or Clayey Fine Sands or en ... ML ~~~i!~ C cnl CL Inorganic Clays ol Low lo Medium Plasllclly, Grave Uy Clays, Sandy :::! " ..JUl?-li Clas Sin Cla g!~& in~5~i--; OL OrganJc SIils and Organic SIity Clays ol Low PlaSUdty. O'ci ., < ~~t! UJ MH Inorganic Elasllc Slls, Mlcacaou• Of Olamaoeoua Fn Sandy orSUty SOIis, Plutlc Slla. ~ifli~ cn;!~~ (!l ., ~ ~u~ij CH Inorganic Clay1 or High Plasl.lcly, Fal Clays. w -z~ (1)0:S'_,t-,; z -OH Organic Clays ol Medium to High f'lasllclly, Organic Sits. u:::: < HIGHLY ORGANIC SOILS PT Peal and Olher Highly Organic SOIis. Dual Gcoop Symbols Are Used For Coarse Grained SoUa Wilh 6% To 12% Anes (PMSing t200 Sieve) And For(CL•ML). Bordertlna Classmcation May Be Represented Wilh Two Symbols Separated By A Sluh. GRANULAR Consistency BlowStfoot• Very loose 0-4 Loose 5-9 SU9hUy Compact 10-19 COl11)act 20-34 Dense 35-69 Very Dense >70 I I I V CHoro7 -"',, CLorOL ., -,, '".,, ~~: IJ:"'" MHorOH '1..U •Numberof Blows of 140 Pound Harn Falling 30 Inches To Drive a 2·Inch O. (1-3/8 Inch I.D.) Split Barrel Sampler COHESIVE (ASTM D-1566 Standard Penetration Consistency BlowStfoot• Strength0 Test). Very Soft 0-4 0-1/2 .. Shear Strength In KSF. Read From Pocket Penetromeler. Soft 6-9 1/2-1 Stiff 10-19 1·2 Very Stiff 20-34 2·4 Hard 35-69 Over4 Very Hard >70 SANO GRAVEL CLAYS ANO SILTS .__--i----,----t~--,...---1 COBBLES BOULOI Fine Medium Coarse Fine Coarse Sieve Sizes 200 "° 10 <4 3/4" 3• 12· U.S. STANDARD SERIES SIEVE CLEAR SQUARE SIEVE OPENINGS Classiftcation of Earth Materials la Based on Field Inspection and Should Not Ba· Construed To lm1 Laboratory AnalyslbUnless So Slalad. (D 30 )2 GW end SW: Cu= ~O GroaterThan 4 For GW and 6 For SW; Cc = O x O Between 1 • 10 10 60 GP and SP: Clean Gravel or Sand Not MesUng Requirement For GW and SW. 'or~ 00 20 40 60 eo GM and SM: Atlerberg Umlt Below "A" Une or P.I. Less Than 4. 1 oo GC and SC: Atlarberg Umil Above • A" Una P,I. Greater Than 7. Uquid Limit (LL) KEY FOR SOIL CLASSIFICATION FIGURE J I I I . i ~ w i:: ~~~ ~ DESCRIPTION OF SUBSURFACE MATERIALS 0:: &.! ~t ~~ ffi Ci:' .o .. ,::,:; oe s~I i THIS SUMMARY Al'f'l.lES ONLY AT THE LOCATION OF THIS BORING AND AT THE TIME OF w 5----.Ult, 5 >-O'ge Cl DRILLING. SUBSURFACE CONDITIONS MAY DIFFER AT OTHER LOCATIONS ANO MAY CHANGE ::E ~ AT THIS LOCATION WITH THE PASSAGE OF TIME. THE DATA PRESENTED IS A SIMPLIFICATION IJ.l ca Cl r.ll OF ACTUAL CONDITIONS ENCOUNTERED. 0 Fill: Clayey SAND (SC). brown. damp, loose to slightly compact Sandy CLAY (CL). brown gray. moist, stiff to very stiff, 5 with trace of gravel 16 s No sample recovery 18.3 109.6 26 D 10 Clayey SAND (SC). brown, moist, slightly compact to compact WA 10.7 33 s 15 WA 10.5 16 s 20 Sand lens Gravels and cobbles 9.8 25 Santiago Formation: Clayey SANDSTONE (SC). light gray, moist, very dense Harder drilling 30 11.1 Auger refusal Boring terminated at Elev. 18.5 ft Groundwater not encountered 35 SAMPLE TYPES: DATE DRILLED: PROJECT NO. 1-111 CARLSBAD OVERHEAD SAN DIEGO COUNTY, CALIFORNIA lg Rock Core 6-6-97 lfil Standard Split Spoon EQUIPMENT/METHOD USED: {Q] Drive Sample CME 95/HSA !ID Bulk Sample SUPERVISOR: LOG OF BORING NO. BH-1 z 0 ~i >"" w'-' ...:l w 49 45 40 35 30 25 20 15 10 !SL_'::![TI=._.:_T:::'.ub~e~S'..'.'..am~pl~e ----~G~-_.::S~P!..A~U:!!.L~O~l~N~G~----•IMlfL!P~A~G~E_:!1~0~F~l'._ _______ ~Fl~G~UR~E~A~ .... I I I ~ ill ~ t:~4? ~~ Cl) ffiQ rno._ 0:: c.e :>uf Ill -----a: 0 ~ 0 >-8,oe ~ 0:: Ill ....l C i:Cl 43 WA 6.3 32 GS 5.7 37 WA 5.6 45 GS 8.0 81 WA 12.9 86 11.0 73 ~ ~Q I Ill l o'-' (I) 0 D s 5 s 10 s 15 s 20 25 s 30 DESCRIPTION OF SUBSURFACE MATERIALS THIS SUMMARY APPLIES ONLY AT THE LOCATION OF THIS BORING ANO AT THE TIME OF DRILLING. SUBSURFACE CONDITIONS MAY DIFfER AT OTHER LOCJ.\TIONS AND MAY CHANGE AT THIS LOCATION WITH THE PASSAGE Of TIME. THE DATA PRESENTED IS A SIMPLIFICATION OF ACTUAL CONDITIONS ENCOUNTERED. Terrace Deposits: Clayey SAND (SC). red brown, damp, compact to dense Silty to Clayey SAND (SM/SC), mottled brown/gray/red, damp, dense Poorly Graded SAND with Silt (SP). brown, damp, very dense . sz . = Perched groundwater at Elev. 14.5 ft Santiago Formation: Clayey SANDSTONE (SC), light olive gray, moist, very dense WA 12.7 71 s 3511 SAMPLE TYPES: DATE DRILLED: lg Rock Core 6-6-97 (fil Standard Split Spoon EQUIPMENT/METHOD USED: (Q] Drive Sample CME 95/HSA rn] Bulk Sample SUPERVISOR; PROJECT NO. 1-111 CARLSBAD OVERHEAD SAN DIEGO COUNTY, CALIFORNIA LOG OF BORING NO. BH-2 ~ P-: ~J Ill, ...l Ill 39 35 30 25 20 15 lO 5 0 ~L.!:[I]~T~u~be::_:S~a~m'..'.!:p~le:._ ____ ~G'..:..·~S'._i_:P~A~U~L~D~l~N~G~ __ _jii,till!ifiil(_!P~A~G~E__!l~O~F'._:2~-------____.!f~IG~U~R~E~A I I I I - ~ b I~ fll ffii ffi 0....., Q...., ~ >--~ ~ Cl 11.1 - -- SAMPLE TYPES: ~ Rock Core [fil Standard Split Spoon [!] Drive Sample (ID Bulk Sample (I] Tube Sample ti~ ~ ~ DESCRIPTION OF SUBSURFACE MATERIALS ~ ~~ ~O.;; t=:-o->U:.t: 5 wl THIS SUMMARY APPi.JES ONLY AT THE LOCATION OF THIS BORING AND AT THE TIME OF ~l 5~.2 oge ~ 0...., DRILLING. SUBSURFACE CONDITIONS MAY DIFFER AT OTHER LOCATIONS AND MAY CHANGE Ul...., AT THIS LOCATION WITH THE PASSAGE OF TIME. THE DATA PRESENTED IS A SIMPLIFICATION ,-I J.tl a:i J.tl fll OF ACTUAL CONDITIONS ENCOUNTERED. 71 s 40 >----- ~-s 87 T 45 ~ Auger refusal r -Boring terminated at Elev. -7 ft -Perched groundwater encountered at Elev. 14.5 ft -~-10 50- - - - --15 55- '--20 60- - - - -'--25 65- - - ~-30 70- - - - --35 75- - - ~-40 DATE DRILLED: ?1 PROJECT NO. 1-1 1 1 6-6-97 CARLSBAD OVERHEAD EQUIPMENT/METHOD USED: SAN DIEGO COUNTY, CALIFORNIA CME95/HSA LOG OF BORING NO. BH-2 SUPERVISOR: G. SPAULDING nmJTA PAGE 2 OF 2 FIGURE A-E I I I TABLE 1 SUMMARY OF PRELIMINARY SEISMIC, GEOLOGIC, AND FOUNDATION INFORMATION Bridge Name: Bridge No.: Geologic Data: Carlsbad Overhead 57C-134 Based on Log of lest Borings for Elm Avenue Undercrossing and the Las Flores Overcrossing bridges, soils consist of compact to dense sands and silty sands. GWS: No groundwater data is available at the site. In Elm Avenue bridge site, groundwater is about 3 to 6 ft below the surface, while in Las Flores Drive bridge site, groundwater is about 42 to 45 ft below the surface. Earthquake Data : Fault: Offshore Zone of Defonnation (Rose Canyon Fault) Distance to Site from Fault: Horizontal Bedrock Acceleration (max): 0.45 g SOIL PROFILE TYPE FORARS CURVES (ATC-32): Lat. 39° 9.8' N Long. J 17° 21.2' W Magnitude: 7 .0 Figure RJ.s (A) (B) (C) ® (E) (F) Liquefaction Potential: Low x --------- "As-Built" Foundation : Piles: Not Used Pile Type(s): NIA Design Load: NIA Est. Ultimate Compression Load for Retrofit: NIA Est. Ultimate Uplift for Retrofit Design: NIA Scour Potential : Yes No I Remarks, Additional Drilling Required: Yes Med ----High ___ _ Spread Footings: Used Allowable Bearing Pressures: NIR X No x I I I 1.0 GENERAL PRELIMINARY GEOTECHNICAL REPORT SEISMIC RETROFIT PROJECT BRIDGE NO. 57C-134 CARLSBAD OVERHEAD SAN DIEGO COUNTY, CALIFORNIA 1.1 Background The County of San Diego is considering the Carlsbad Overhead (Bridge No. 57C-134) for seismic retrofit. The bridge site is shown in Figure 1. The bridge is located along Carlsbad Boulevard approximately 1.0 km (0.6 mi.) northwesterly of Elm Avenue. 1.2 Existing Design Information We have reviewed plans of the Carlsbad Overhead provided to us by Moffatt & Nichol Engineers. The pertinent bridge plans used in our study are presented in Appendix A. The existing bridge was built in 1925 by California Deparonent of Transportation, Division of Structures under Contract No. M-111. In 1935, the bridge was widened. The bridge has five spans with individual span lengths varying from 8.2 to 13.7 m (27 to 45 ft). The total length of the bridge is 50.3 m (165 ft) and the bridge is skewed to the right by 454 degrees. The net width of the bridge is 13.7 m (45 ft) with an overall width of 15.7 m (51.5 ft). The bridge consists of five simple CIP/RC "T" beam girder spans supported by two closed-end backfilled reinforced concrete strutted column bent abutments and four reinforced concrete column bents. All bridge foundations are shallow foundations. 1.3 Scope of Work In general, the purpose of our investigation was to review the existing foundation data and to develop parameters for the seismic retrofit evaluation. Our scope of work consisted of: a brief site visit and reconnaissance, review of as-built plans, evaluation of geotechnical foundation parameters, and preparation of this report. Specifically, we assessed the following geotechnical information: • • • • Spring constants for spread footings, Lateral resistance for abutment walls and spread footings, Ultimate bearing capacity, and Liquefaction potential C:IPROJECTSIMOFF A mRETROFlnBR.S7C 134.DOC I I I Carlsbad Overhead Moffatt & Nichol Engineers 1.4 Pertinent Reports and Investigations GDC Project No. 1-1 I I Page 2 Our understanding of this project is based on discussions with Moffatt and Nichol Engineers, our site visit, and our review of the available plans and bridge summary report. A list of references reviewed is provided in Section 5.0. 2.0 PRELIMINARY SEISMIC, GEOLOGIC, AND FOUNDATION DA TA A summary of existing conditions, and seismic design considerations is presented in Table I. Additional as-built foundation details are summarized in Table 2. 3.0 DISCUSSION AND RECOMMENDATIONS 3.1 Soil Conditions No Log of Test Boring was provided for this bridge. However, Logs of Test Borings from the Elm A venue Undercrossing and the Las Flores Drive Overcrossing bridges were available (see Appendix B). These bridges are within approximately I.I km (0.7 mi.) from the subject bridge. The subsurface investigation at the Elm Avenue Undercrossing consisted of three driven cone borings. The depths of exploration ranged from Elevation 23.6 to 18.6 m (75.5 to 61 ft). The soils encountered consisted of silty sands, sands, and sandy gravel. Penetration resistances in excess of I 00 are reported in the logs. The subsurface investigation at the Las Flores Drive Overcrossing consisted of advancing two 2.5-cm (I-in.) sample borings. The zone of exploration was from Elevation 23.8 to 8.5 m (78 to 28 ft). The soils encountered included sands and silty sands. The penetration resistances of the 2.5-cm {I-in.) sample borings varied between 100 to 4000 blows per foot. Based on our site visit at the Carlsbad Overhead, we noted that exposed soils consisted of formational soils comprised of cemented sands and sandstones. No evidence of seepage was noted. The approximate ground surface elevation underneath the bridge is 7.3 m (24 ft). For purposes of our study, we assumed that the subsurface soils are generally comprised of compact to dense sands and silty sands. We assumed the soils had an equivalent standard penetration test (SPT) blowcount of 30 and average total unit weight of 1,922 kg/m3 (120 pct). 3.2 Groundwater Conditions Groundwater was encountered in Elm Avenue bridge site between Elevations 21 and 21.8 m (69 and 71.5 ft) or approximately 0.9 to 1.8 m (3 to 6 ft) below the ground surface. In Las Flores Drive bridge site, groundwater was reported to be between Elevations 12.8 to 14.0 m (42 to 46 ft) or approximately 9.45 to 10.4 m (31 to 34 ft) below the ground C:IPROJECTS\MOFF A ffiRETROFl1\BR.l7C 134.00C I I I Carlsbad Overhead Moffatt & Nichol Engineers GDC Project No. 1-111 Page 3 surface. Therefore, a potential for shallow groundwater at the Carlsbad Overhead bridge site exists. 3.3 Seismic Parameters 3.3.1 Response Spectra It is our understanding that the Department of Transportation (Caltrans), Engineering Service Center has not developed a recommended response spectra for the Carlsbad Overhead Bridge. We recommend using a bedrock acceleration of 0.45g and ATC-32 Figure R3-8 for response spectra. Our response spectra recommendations are based on our review of the faults in the general area of the bridge as well as DMG OPEN-FILE-REPORT 92-1. According to our review, the controlling fault for the Carlsbad Overhead Bridge is the Offshore Zone of Deformation (Rose Canyon Fault). The magnitude associated with this fault zone is reported to be 7. The estimated bedrock acceleration for the Carlsbad Overhead site is approximately 0.45 g. We characterized the subsurface soil profile as Type D per ATC-32 criteria 3.3.2 Spread Footings All foundations are supported on spread footings. A summary of as-built foundation dimensions and characteristics are .presented in Table 2. The ultimate bearing capacity of the spread footings was estimated by assuming a friction angle of 32 degrees. Spring constants for the spread footings were estimated by using low strain shear modulus values based on energy corrected blow count and published correlation by Sykora (1987) shown in Figure 2 and dynamic spring constant formulas for rigid footings. The calculated spring constants are low strain values and are applicable at small displacements. They should be considered as initial values for starting the analysis. If calculated displacements using the spring constants are such that the ultimate bearing capacity or lateral resistance is exceeded, softer springs should be used so that the limiting values of bearing capacity and ultimate lateral resistance are not exceeded. Ultimate lateral capacity of spread footings is a function of both sliding resistance and passive soil resistance. In our recommendations, we have provided design parameters for both sliding resistance and the ultimate passive soil resistance acting on the side of the foundation. The ultimate passive soil resistance does not include any contribution from sliding. In addition, for passive resistance of spread footings, we assumed that the footing excavations are backfilled with compacted granular fill. The recommended foundation capacities and spring design parameters are summarized in Tables 3 and 4. · C:\PROJECTS\MOFFAffiRETROFffiBR57CJ34.DOC I I I Carlsbad Overhead Moffatt & Nichol Engineers 3.3.3 Pile Foundations Pile foundations were not used for this bridge. 3.3,4 Lateral Load Pile Response of Outer Bent Columns GDC Project No. 1-111 Page 4 At the request of Moffatt and Nichol, we evaluated the lateral load pile response of the outer bent columns of the bridge using the finite difference computer program PILED/G (GEOSOFT, 1988). The program uses non-linear (p-y) soil resistance-lateral deflection curves to represent soil characteristics. These columns extended from the bridge deck to a depth of 1.8 to 3 m (6 to 10 ft) below the ground to the top of the footings. The columns were comprised of 0.6-m (2-ft) square reinforced concrete columns. As requested by Moffatt and Nichol, we applied the lateral load at the ground surface, considered both free and fixed head conditions, and used 40 percent of the EI of the column. We understand that Moffatt and Nichol models the bridge and bridge columns as structural elements with the buried portion of the column and associated foundations modeled as an equivalent structural element. The_characteristics of this equivalent element are developed from the results of our . analyses. Due to the relative shallowness of the column embedments, the lateral load response of the columns corresponded to the behavior of a short, rigid pile. The variation of pile deflection, pile moment, and shear with depth for the cases evaluated are presented as Figures 3 through 8. A summary of the variation of pile displacement at the ground surface and maximum pile moment with applied load is presented in Table 5. 3.3.5 Ultimate Lateral Capacity of Abutment Walls The ultimate lateral capacity of an abutment wall is a function of the height of the abutment wall which is acted on by the passive soil pressure on the backfill. We have provided recommendations for the average ultimate passive soil pressure acting on the abutment wall. This dynamic value is based on a passive pressure coefficient of 10.3 for the compacted backfill providing an average pressure of 239 kPa (5 ksf) for an 2.4-m (8- ft) high wall. The ultimate static lateral pressure was increased by (1/0.65) to account for short-term dynamic loading and use of peak ground acceleration. The ultimate lateral capacity for wall heights 2.4 m (8 ft) and above should be taken as 369 kPa (7.7 ksf). For wall heights less than 2.4 m (8 ft), we recommend that the ultimate capacity be obtained by multiplying 369 kPa (7.7 ksf) value with the ratio (H/2.4) where His the wall height in meters, { (H/8) for H in feet}. Passive pressures are mobilized when the deflection of the wall reaches 0.02 H meters ( or feet), where H is the wall height in meters ( or feet). The estimated abutment wall stiffness then becomes the ultimate lateral capacity of the wall divided by the wall displacement. 3.4 Liquefaction Potential Groundwater data for the site is unavailable. Although there is a potential for shallow groundwater at the site, based on borings at nearby bridge sites, our preliminary estimate C:IPROJECTSIMOFFA TI\RETROFl1\BR57CIJ4.DOC I II ~ I Carlsbad Overhead Moffatt & Nichol Engineers GDC Project No. l-111 Page 5 of liquefaction potential for Carlsbad Overhead is low. However, since there is no Log of Test Borings available for this bridge, we recommend drilling two borings and conducting additional liquefaction analysis based on the results of the new subsurface data. 4.0 LIMITATIONS No field investigation was performed at the sites. In view of past grading and the general geology of the area, possibility of different conditions can not be discounted. It is the responsibility of the owner to bring any deviations or unexpected conditions observed during construction to the attention of the Geo technical Engineer. In this way, any required supplemental recommendations can be made with a minimum of delay. This report was prepared in accordance with generally accepted geotechnical engineering principles and practice. The professional engineering work and judgments presented in this report meet the standard of care of our profession at this time. No other warranty, expressed or implied, is made. 5.0 REFERENCES Available plans as follows: State of California, California Highway Commission, "Bridge over Atchison Topeka & Santa Fe RY. Near Carlsbad-Sta. 478+30.69, San Diego County": General Plans. abutment details, bent details, and miscellaneous plans dated 1925. State of California, California Highway Commission, "Widening of Bridge over Atchison Topeka & Santa Fe RY. Near Carlsbad-Sta. 478+30.69, San Diego County": General Plans and miscellaneous details dated 1934. Log of Test Borings for "Elm Avenue Undercrossing". Log of Test Borings for "Las Flores Drive Overcrossing". References: Applied Technology Council, ATC-32, 1996, "Improved Seismic Design Criteria for California Bridges: Provisional Recommendations". Arya, Suresh; O'Neill, Michael, and Pincus, George, 1979, "Design of Structures for Vibrating Machines," Gulf Publishing Company, Houston, 1979, pp.191. California Department of Conservation, Division of Mines and Geology, 1992, "Peak Acceleration From Maximum Credible Earthquakes in California (Rock and Stiff-Soil Sites)", DMG OPEN-FILE REPORT 92-1. C:IPROJECTSIMOFFA TI\RETROFIT\BR57Cl34.DOC I I . I Carlsbad Overhead Moffatt & Nichol Engineers GDC Project No. 1-11 I Page 6 Department of Transportation, Engineering Service Center, Office of Structural Foundations-MS #5, Structure Foundations Branch, 1996, "Acceleration Response Spectra for Local Agency Seismic Retrofit Bridges", Memorandum, August 13, 1996. Local Agency Seismic Retrofit Contract No. 59Y025, EA 53-965100. Earth Technology Corporation, 1986, Seismic Design of Highway Bridge Foundations, A Report Prepared for the U.S. Department of Transportation, Report No. FHW A/RD-86/ l O l. GEOSOFT, 1988, "PILED/G, Laterally Loaded Drilled Piers and Piles", A Finite Difference Program for Calculating Lateral Load Response of Piles, 1442 Lincoln Avenue, Ste. 146, Orange, CA 92667. State of California Department of Transportation, 1990, Bridge Report, Carlsbad Overhead (Carlsbad Boulevard -0.6 miles northwesterly of Elm Avenue, FAU S352)", May 22, 1990. Sykora, D., 1987, "Examination of Existing Shear Wave Velocity and Shear Modulus Correlations in Soils", U.S. Department of the Anny, Waterways Experiment Station, Corps of Engineers. C:IPROJECTSIMOFF A TnRETROFl1\BR.17C 134.00C I I I I TABLE 1 SUMMARY OF PRELIMINARY SEISl\.flC, GEOLOGIC, AND FOUNDATION INFORMATION Bridge Name: Bridge No.: Carlsbad Overhead 57C-134 Geologic Data: No Log of Test Borings was available for this bridge. Based on Log of Test Borings for Elm Avenue Undercrossing and the Las Flores Overcrossing bridges located approximately I. I km from the subject bridge, soils consist of compact to dense sands and silty sands. GWS: No groundwater data is available at the site. In Elm Avenue bridge site, groundwater is about 3 to 6 ft below the surface, while in Las Flores Drive bridge site, groundwater is about 42 to 45 ft below the surface. Earthquake Data : Fault: Offshore Zone ofDefonnation (Rose Canyon Fault) Distance to Site from Fault 7 km Horizontal Bedrock Acceleration (max): 0.45 g Lat. 39° 9.8' N Long.111°21.2·w Magnitude: 7.0 SOIL PROFILE TYPE FOR ARS CURVES (ATC-32) : Figure R3-8 (A) (B) (C) ® (E) (F) Liquefaction Potential: Low_.....;.;x:..•--Med ___ _ High ___ _ "As-Built" Foundation: See Table 2 Piles: Not Used Pile Type(s): NIA Design Load: NI A Est. Ultimate Compression Load for Retrofit: NIA Est. Ultimate Uplift for Retrofit Design: NIA Scour Potential : Yes No x Remarks: Spread Footings: Used Allowable Bearing Pressures: See Tables 3 and 4 • The liquefaction potential for this bridge was based on limited subsurface soil and groundwater data. [f the conditions considered in the estimate differ from the actual estimate, the liquefaction potential for the site may be high. Additional Drilling Required: Yes X No Of£S Kul Bhush~ Ph.D., G.E. C:\PROJECTS\MOFF A TI\RETROFIT\BRS 7C I J4.DOC UL BHUSHA, I"'"'' Mo. GE G00144 ~)' p /2.-?,/--j 7 . >t-/J CHN\_ __ . I I ~ .. '.1 i I I 2.0 0.7g (0. 7g) 1.5 ,.... 0, z Q < 1.2 c:: l.,.J "" u u <( ...; 0.8 <( ,.... u ...., a.. Vl 0.4 0.0 0 50 40 ·- z ...., ~ 30 .., u <( ...., c.. V) ci <. 20 c:: u .., Bi 10 0 0 Curve -ror Nole: SOIL PROFILE TYPE D MAGNITUDE: 7 .25::::::: 0.25 ceok oround occeterolion volues not ,,,· oorentheses ore for rocK (Soil :>rofiie i)'l)e 9) ond oeok ground oc:eterot,on volues in porentheses ore for Soil 0rofile •)'l)e i)_ curve for Carlsbad OH ( 0,4~9) _ 2 3 ?£RIOD (sec) ! 0.7g (0.79) Cor/sbod QH, (0,45g) 0.69 (0.69) 0.5g (0.59) 0.49 {0.-4-4q) 0.3g (0.36g) D.2q (0.289) 0.lq {0.16g 2 J PERIOD {sec) Figure R3-8 Proposed ARS curves for soil type O (M .. 7 .25::: 0.25) ATC-32 B0S·Recommendations, Section 3: Loads 4 4 37 TABLE 2: SUMMARY OF AS-BUil T FOUNDATION CHARACTERISTICS Spcead Foollngs or Pile Caps No. ol Dlmension1 (ft.) b.o.J. elev. Loc:aH00 Elements L B T D (ft.I Ben! I 4 5.0 S.0 2.0 4109 301033 Bent 2 , 53.S 4.0 2.0 510 7 17 Benll 1 53.5 4.0 2.0 5107 17 Beol4 1 53.5 4.0 2.0 5107 19 BenlS 1 S3.S 4.0 2.0 s101 11.5 Bent& I 5.0 5.0 2.0 310S 24 lo 25 NOTE$ f 2 J ' 5 • 1 Local Agency Seismic Retrofit Project GOCPr No.1-11 Bridge Name: Carlsbad Overhead Bridge Number: 57C-134 qallow Number (ks!) Type Total Vertical N/R NIA NIA NIA NIR NIA NIA NIA NIR NIA NIA NIA NIR NIA NIA NIA NIR NIA NIA NIA N/R NIA NIA NIA , • fO 11 PU. Foundaliana Qallow PIie Baller (klpa) Peoelf•lion NIA NIA NIA NIA NIA NIA NIA NIA NIA NIA NIA NIA NIA NIA NIA NIA NIA NIA u fl " - Pile Tip Elev.(ft.l Convnents NIA NIA NIA NIA NIA NIA f5 " Group Delta Consultants Cl"Jn1n"I' I I I I. 2. 3. 4. NOTES FOR TABLE 2: SUMMARY OF AS-BUILT FOUNDATION CHARACTERISTICS Location refers to the foundation element for which the information is provided ( e.g. Abuonent I or Bent 2). No. or Elements refers to the number of spread footing elements for the specified location. Example. if the no. of elements is 2, there are rwo spread footings for the location. L refers to the length of the spread footing or pile cap. The length of the foundation is the dimension perpendicular to the longitudinal axis of the bridge. If there is more than one element, a range of the lengths is provided. B refers to the width of the spread footing or pile cap. Toe width of the foundation is the dimension perpendicular to the transverse axis of the bridge. If there are more than one element, a range of the lengths are provided. 5. T refers to the thickness of the spread footing of pile cap. 6. D refers to the embedment depth of the spread footing or pile cap as measured from the minimum ground surface to the bottom of the footing or pile cap. 7. b.o.r. elev. refers to the estimated or reponed elevation corresponding to the bottom of the spread footing or pile cap. 8. q ..... refers to the plan reported allowable bearing pressure. If this values could not be obtained from the plans, N/R (Not Reported) is shown. If there are no spread footings, NIA (Not Applicable) is shown. 9. Type refers to the reported type of pile foundation used for the bridge. I 0. Total refers to the total number of pile foundation elements in the specified pile cap. If the number could not be accurately confmned, N/R (Not Reported) is shown. If there are no pile foundations. NI A (Not Applicable) is shown. 11. Vertical refers to number of pile foundation elements which are vertical. If the number could not be accurately determined, N/R (Not Reported) is shown. If there are no pile foundations, N/ A (Not Applicable) is shown. 12. Batter refers to number of pile foundation elements which are battered. If the number could not be accurately determined, N/R (Not Reported) is shown. If there are no pile foundations. N/ A {Not Applicable) is shown. 13. Q.,,_ refers to the plan reported design capacity of the pile foundation element. If this values could not be obtained from the plans, N/R (Not Reported) is shown. If there are no pile foundations. N/A (Not Applicable) is shown. 14. Pile Penetration refers to the length of pile foundation in the ground. If this information could not be obtained from the plans, N/R (Not Reported) is shown. If the bridge was supported on spread footings, NIA {Not Applicable) is shown. 15. Pile Tip Elev. (rt) refers to the reported average pile tip elevation of the pile foundation. If this information could not be obtained from the plans, N/R (Not Reported) is shown. If the bridge was supported on spread footings, NIA (Not Applicable) is shown. 16. This column is for additional comments. TABLE 3: SUMMARY OF RECOMMENDED BRIDGE FOUNDATION CAPACITIES Bridge Name: Carlsbad Overhead Bridge Number: 57C-134 Average Abutment Wall Pressure Foundations • Lateral Resistance of Footim or Pile Cap Q ull (kips) p avg (ksf) limob Type or Qup A axial Pult A. lateral Total Passive Force (kips) Sliding Location H > 8 ft. H < B ft. (inches) q ult (ksf) (kips) (inches) (kips) (inches) Transverse Longitudinal Coefficient Spread Bent 1 7.7 7.7 X (HIB) 0.02•H Footing 20 65 NIA NIA NIA 48 48 0.45 Spread Bent2 NIA NIA NIA Footing 15 140 NIA NIA NIA 38 600 0.45 Spread Bent3 NIA NIA NIA Footing 15 140 NIA NIA NIA 38 600 0.45 Spread Bent4 NIA NIA NIA Footing 15 140 NIA NIA NIA 38 600 0.45 Spread Bents NIA NIA NIA Footlng 15 140 NIA NIA NIA 38 600 0.45 Spread Bent6 7.7 7.7 x (H/8) o.02•H Footing 20 60 NIA NIA NIA 48 48 0.45 Notes 1 2 3 ., 5 6 7 8 9 10 11 12 13 • The foundation capacities shown are our best estimates. Since the Log of Test Borings for this bridge is not available, the actual foundation capacities may vary by 50 %. Local Agency Seismic Retrofit Project GDC ProjectNo.I-111 Group Delta Consultants 5/29/97 I I I NOTES FOR TABLE 3: SUMMARY OF RECOMMENDED FOUNDATION CAPACITIES I. Location refers to the foundation element for which the information is provided. For example. if the location is Abutment I, the information provided is for the abutment 2. 3. The recommended average ultimate abutment wall pressure for wall heights greater than or equal to eight feet. If the wall height is less than 8 feet, then the average abutment wall pressure is computed as follows: P~,=7.7 x (H/8). This equation prorates the maximum wall pressure by the wall height divided by 8 feet. 4. This column represents the wall displacement necessary to mobilize the average abutment wall pressure. This displacement can be used with the wall pressure to compute the equivalent abutment stiffness. 5. Type refers to the foundation type at the specified foundation location. For example, Spread Footing refers to spread footings and Pile refers to pile foundations. 6. If the foundation type is specified as Spread Footing then the reported value refers to q.,, which is the estimated ultimate bearing capacity of the spread footing. Conversely, if the foundation type is pile, the value refers to Q.,, which is the estimated ultimate axial capacity of a single pile foundation element. The q,. values shown apply for vertical loads only and do not take into account lateral loads. For spread footings with lateral loads ranging from 20 to 40 ¾ of the total vertical loads, approximately 20 to 60 ¾ reduction in q,. values are anticipated. 7. If the foundation type is specified as spread footing, then the ultimate uplift capacity of the footing includes the weight of the footing and the soil above the footing. For a pile foundation the value refers to the estimated ultimate uplift capacity of a single pile foundation element. 8. The value specified is the axial displacement necessary to mobilize the ultimate pile capacity. 9. P .. , refers to the ultimate lateral capacity of a single pile for the corresponding specified lateral displacement I 0. This column refers to the lateral pile displacement necessary to mobilize the ultimate lateral capacity of the pile. 11. This value corresponds to the passive resisting force developed on the specified side of the spread footing or pile cap. This value does not include any lateral resistance from piles. This values is assumed to be fully mobilized under a displacement equal to approximately 2 percent of the foundation thickness. 12. This value corresponds to the passive resisting force developed on the specified side of the spread footing or pile cap. This value does not include any lateral resistance from piles. This values is assumed to be fully mobilized under a displacement equal to approximately 2 percent of the foundation thickness. 13. This value corresponds to the coefficient of friction along the bottom of the spread footing. This value is assumed to be fully mobilized under a displacement equal to approximately 2 percent of the foundation thickness. For pile foundation, NIA (Not Applicable) is shown. ,-------l ' -~,:, _..,., ,J t;::11111 .. TABLE 4: SUMMARY OF RECOMMENDED FOUNDATION STIFFNESS Bridge Name: Carlsbad Overhead Bridge Number: 57C-134 Spread Fooling or Pile Cap Stiffness Vertical Horizontal (kips/in) Location (kips/inch) Transverse Bent1 8.40E+03 1.10E+04 Bent2 2.60E+04 2.10E+04 Bent3 2.60E+04 2.10E+04 Bent4 2.60E+04 2.10E+04 Bents 2.60E+04 2.10E+04 Bent6 8.40E+03 1.10E+04 Notes 1 2 2 Local Agency Seismic Retrofit Project GDC Project No.I-111 longitudinal 1.10E+04 2.10E+04 2.10E+04 2.10E+04 2.10E+04 1.10E+04 2 Rocking (kip•inch/rad) Transv. Axis Long. Axis 8.50E+06 8.50E+06 1.40E+07 1.60E+09 1.40E+07 1.60E+09 1.40E+07 1.60E+09 1.40E+07 1.60E+09 8.50E+06 8.50E+06 2 2 Torsional (klp*inch/rad) 5.40E+06 8.20E+08 B.20E+08 8.20E+08 8.20E+08 5.40E+06 2 Single Pile or CIDH Vertical (kips/inch) NIA NIA NIA NIA N/A NIA 3 Horizontal (kips/inch) Comments NIA NIA N/A NIA N/A NIA 4 5 Group Delta Consultants J::/?010'7 I I I I.· 2. 3. 4. NOTES FOR TABLE 4: SUMMARY OF RECOMMENDED FOUNDATION STIFFNESS Location refers to the foundation element for which the information is provided. For example. if the location is Abutment 1, the information provided is for the abutment. Toe recommended foundation stiffnesses are for small-strain shear modulus values and dynamic spring constant formulas for rigid footings. Toe calculated spring constants are small strain values and are applicable for small foundation displacements. If the calculated displacements using the spring constants are such that the ultimate bearing and lateral resistances are exceeded, softer springs should be used. Foundation displacements which would generate shear strains on the order of a few percent would result in a reduction of stiffness on the order of S to IO percent. Toe spring stiffness for the axial direction of the pile is based upon the ultimate pile capacity and the displacement necessary reach the ultimate capacity. Toe spring stiffness for the lateral direction is based upon our lateral load analyses for venical piles. The stiffness is based on the ultimate lateral load divided by the lateral displacement needed to reach the ultimate value. For battered piles, the horizontal component of the axial stiffness can be used instead. S. This column is for appropriate comments.