5 of 7_GeoRpt_White River_OR Hwy 35

Draft Geotechnical Data

OR FS ERFO 2007(1)-11(1)

Highway 35 Betterment

This document is a draft and should NOT be relied upon to determine final conditions for bidding.

Final documents will be available during the advertisement period.

APPENDIX C

Pressuremeter Test Report

INSITU TECH INC.

Beaverton, Oregon www.insitutechinc.com

Pressuremeter Testing Report

Proposed Hwy 35 Bridge White River Mt Hood, OR

For

FHWA-WFL

Vancouver, WA

November 2008

TABLE OF CONTENTS

PAGE

TESTING OBJECTIVES AND AUTHORIZATION 3

EQUIPMENT, TESTING, AND DRILLING METHODS 3

TEST RESULTS 5

INTERPRETATION AND PMT PARAMETER RECOMMENDATIONS 7

DEEP FOUNDATION CONSIDERATIONS 9

REFERENCES

APPENDIX 1 PRESSUREMETER CORRECTED CURVES

APPENDIX 2 FIELD DATA SHEETS

TESTING OBJECTIVES AND AUTHORIZATION

A replacement bridge is proposed adjacent to the existing Oregon State Hwy 35 Bridge over the

White River in the Mt. Hood National Forest, OR. The proposed bridge location is adjacent to the existing on the downstream side of the present bridge structure; and, in the approximate location of the earlier bridge replaced in the early 1950’s by the present span. The replacement is of longer span and higher deck elevation to permit less obstruction to the outwash floods and accompanied debris carried off Mt. Hood. It is likely a deep foundation will be selected as the principal bridge span supports at the north and south ends.

The prebored Pressuremeter test (PMT) was selected to supplement the Standard Penetration Test (SPT), as well as logging, to characterize subsurface conditions and to assist in foundation design and analysis under both extreme limit state and serviceability conditions. Subsurface conditions at the site were identified by earlier site investigations. These soil conditions were determined to be granular course sands with occasional gravel. This report details the successful PMT investigation of the site, reports property variations, and discusses the application of the PMT data to deep foundation design.

Scott Corn, Vice-President of Haz-Tech Drilling, Meridian, Idaho, gave authorization in September

2008 for InSitu Tech Inc. to proceed and 4 days of PMT testing was conducted from October 15-18, 2008.

All mud rotary drilling was conducted by Haz-Tech with a CME track mounted drilling rig operated by Mike

Corn.

EQUIPMENT, TESTING, AND DRILLING METHODS

Prebored PMT testing was conducted using a TEXAM (Roctest Inc., NY) hydraulic unit operating a long NX probe. The long probe has an approximate 2.8 in (70mm) initial diameter and a saturated deflated volume of approximately 113 cu. in (1850cc). The probe is a mono-cellular, strain controlled, hydraulic device and the system is saturated with 20%/80% antifreeze to water solution to aid testing in sub-zero temperatures. Testing was conducted to the strain controlled procedure B of ASTM 4719-87 with reload cycles following initial elastic expansion. Some direct PMT foundation design procedures, and applications of elasticity, call for this reload modulus, Er, to be used.

To ensure bore hole stability, Haz-Tech utilized a mud rotary system with the cased borehole drilled and advanced to immediately above a proposed PMT test zone. Drilling of the 4 ft deep PMT test sections was made by either a 2-15/16 in. diameter tri-cone roller bit or with 3-1/8 inch tri-cone roller bit circulating mud down the NW-J drill string to lift sand and gravel cuttings from the roller bit and minimize any stress relief. The first PMT zone in borehole B10 from 9 ft to 13 ft below G.L. with the 2-15/16 inch bit was not open below 10 ft, and no test was attempted. In all other tests, mud circulation and borehole stability was excellent with the remainder of the test zones drilled with the 3-1/8 inch roller bit in granular soils. Occasionally some cuttings remained at the bottom of the test zone hole below the probe. This is not detrimental to high quality PMT testing. Two PMT dedicated boreholes were drilled: B10 on the north bank and B7 on the south bank, with both in close proximity to the existing bridge and of the order 12 ft.

to 15 ft. above the streambed elevation. Five (5) successful tests were conducted in each borehole for a total of 10 tests. It is understood the existing bridge shallow mat footings supporting the piers are approximately 15 to 18 ft. below streambed. It is likely the upper zones in both B10 and B7 boreholes may have been drilled through fill placed in the excavation for these mats, or through other fill placed during the 1950’s bridge contract.

The PMT probe is approximately 4 ft. long overall to the connection with the NW-J support rod and is hollow to permit mud passage through the center as the probe is lowered into the test hole. Probe entry requires a minimum of 2.8 ft. to 3 ft. into the test zone for a valid test. Typically, the probe entered the hole to within 6 in., or less, of the bottom of the carefully prepared drilled test section. Borehole quality was determined to be very good to excellent for all tests.

TEST RESULTS

To measure net soil cavity expansion properties, hydraulic PMT raw field data is corrected for:

membrane resistance, system volume expansion, and hydraulic head pressure down the line to the probe.

Calibrations for membrane resistance and volume losses were conducted on site. Adjustment for hydraulic head in the supply lead was made based on the depth to the probe centerline below the control unit. All

PMT reported parameters are from the corrected data. By convention all calculated PMT modulus values employ a fixed Poisson's ratio of 0.33 and the depths reported for each test were measured from the ground level down to the centerline of the expanding section of the probe. The probe center was 18 in. (0.43m) above the bottom of the probe shoe. Appendix 1 shows PMT plotted test results for all 10 tests, where each test is expressed in plots of borehole cavity pressure (ksf) vs radial expansion (%). Radial expansion during a test is described as probe radius increase, dR, divided by original probe radius, Ro, which is related to soil circumferential strain. Cylindrical expansion by a PMT reveals the soil’s elastic range of behavior, as well as the limiting cavity pressure, PL, dictated by the soil’s shear strength. At the White River Bridge site, all soils tested show drained behavior with considerable strength, and final limit pressures were beyond the capability of the Texam PMT unit. However sufficient plastic behavior is measured to give reasonable estimates of PL.

To assess test quality, InSitu Tech Inc. offers a maximum 3 star (***) quality rating to any completed tests which contain: a well defined modulus, sufficient plastic behavior to approach a limit pressure, PL, and a curve that shows no adverse effects from disturbance. The net limit pressure Pl* reported in Table 1 below, is given by:

Pl* = PL - Po

Where: Po = at rest total horizontal stress.

Pl* is a measure of the increase in horizontal stress beyond Po to mobilize the soil shear stiffness and strength. Typically PL used in the above equation is taken as the clear maximum pressure at twice the cavity expansion or visual extrapolation of pressure from the expansion curve (Appendix 1) to the asymptotic limit.

In these dense soils for evaluation of Po the average saturated unit weight and coefficient of earth pressure at rest, Ko, was taken at 125 lb/cu ft and 0.5 respectively. Pore water pressure was taken as hydrostatic at the river elevation 15 feet below G.L.

Table 1 reports the summary PMT parameters and soil descriptions. Applying the theory of linear elasticity to infinitely long cavity expansion permits the calculation of both the initial modulus and the subsequent unload-reload modulus. For those tests with multiple reload portions the final modulus, Er, is calculated and reported in Table 1. It is accepted practice that the measured initial PMT modulus, Eo, be called a Menard Modulus and is calculated from borehole expansion where an assumed Poisson’s ratio of 0.33 is used. All test results in Appendix 1 indicate excellent borehole quality without disturbance, as these effects were minimized by careful drilling of the test section. No soil creep was observed in any test.

TABLE 1 PRESSUREMETER TEST RESULTS

PROPOSED NORTH PIER B10

Test Number, Quality & B/H

Depth Soil Type

PMT Net Limit Pressure Pl*

PMT

Menard Initial Modulus Eo

PMT

Reload Modulus Er

Comments

(ft) (ksf) (ksf) (ksf) 3 **

14.5 V. dense

coarse sand

>100 2228 6635 Drained-two U/R

4 **

22.0 Dense med

sand

68 723 3648 Drained-two U/R

5 ** 31.0 Dense med sand

>90 1248 5342 Drained- two U/R

6 **

51.25 V. dense

95 2205 4868 Drained- one U/R

7 **

72.0 Dense

Gravelly

>120 2987 6041 Drained- two U/R

NOTE: Missing test numbers are calibration tests

PROPOSED SOUTH PIER B7

Test Number, Quality & B/H

Depth Soil Type

PMT

Net Limit Press Pl*

PMT

Menard Initial Modulus Eo

PMT

Reload Modulus Er

Comments

(ft) (ksf) (ksf) (ksf) 8 **

12.0 V. dense sand >105 2052 8140 Drained- two U/R

9 ** 16.0 Dense gravelly sand

>105 1496 4877 Drained- one U/R

10 ** 26.75 V. dense silty sand

>110 2308 7478 Drained- one U/R

11 ** 51.33 Dense silty

80 1408 4066 Drained - one U/R

12 ** 72.0 V. dense silty

>120 1934 5170 Drained - one U/R

The corresponding SPT blow counts in these soils do fluctuate between high reportable numbers and refusal, probably because of the variable amount of gravel which can occasionally be broken up by the SPT shoe held by the very dense sands. The summary material descriptions given in Table 1 and on the PMT plots in Appendix 1 are based on field notes (given in Appendix 2), observation of cuttings, driller interpretation, and probe condition after removal from the test zone.

INTERPRETATION AND PMT PARAMETER RECOMMENDATIONS

All tests reveal property variations in dense to very dense angular sands, occasionally silty on the south B7 location, and of higher stiffness in the upper 15 ft at both locations if compared to distributions for normally consolidated sand. Limit pressures and stiffness are considerable and at the upper end for dense sands. The ratio of PMT modulus, Eo, to net limit pressure, Pl*, for granular normally consolidated soils are typically less than 11; however, at this site, the ratio is above 11 and strongly indicates all these deposits are to varying degrees over consolidated and/or show some cementation. Net limit pressure place the angle of apparent shearing resistance, φ, above 40 degrees. Consistent for clean sand a trend of generally increasing stiffness with depth, below the previously mentioned upper zone, is found and illustrated in Figure 1 below. The shallowest tests, # 3 in B10 and # 8 in B10, are omitted for two reasons: firstly, as previously mentioned, they may be in compacted fill from the existing bridge construction activities, and second, the slope may influence these layers contribution to deep foundation lateral behavior, but the slope has not influenced the PMT measured result.

All PMT measured modulus values in the upper 75 feet here reveal stiff, dense to very dense, sands. As a measure of the difficulty in using SPT data directly in design in these soils the PMT stiffness correlation between the initial modulus, Eo, to SPT blow count relationship, reported by J.-L.Briaud (Ref

1), is Eo (kPa) = 383N in NC sands and can be used here for illustration. For those PMT tests for which

Insitu Tech Inc recorded SPT results the measured stiffness is between 3 to 4 times the Eo predicted by the correlation. Thus the silty and gravely angular sands at the White River Bridge exhibit possible over consolidation, very dense unit weights, high stiffness, and high strength.

PMT Eo with Depth

B10

B10

B10

B10

B7

B7

B7

B7

-80

-70

-60

-50

-40

-30

-20

-10

0 1000 2000 3000 4000

Modulus (ksf)

D ep th b el ow

G .L

FT

Shallowest test in both B/H's ommitted

Figure 1: PMT Initial Modulus with Depth

Figure 1 illustrates well that differences between borehole B7 and B10 do exist. The south B7 location shows more uniform trend with depth and the north B10 location has a clear increase with depth.

Borehole B10 illustrates Eo increasing linearly at a rate of 40 ksf/ ft -while B7 is uniform at 1800ksf.

Design should proceed on that basis.

DEEP FOUNDATION CONSIDERATIONS

Subsurface conditions at the proposed location of the bridge are revealed in borings B7 and B10 to be excellent for axial and lateral capacity for either shallow foundation or deep foundation options.

InSitu Tech Inc understands that as well as LRFD axial load considerations the lateral load extreme event is of concern from debris flow impact to the structure. It was understood at the time of the site investigation that FHW- WFL will likely select the deep foundation option of a single drilled shaft for both north and south pier supports. The complete profiles of PMT properties at both locations permit a complete axial and lateral analysis to be undertaken based on PMT design rules. However, constructability options such as the use of casing and slurry do modify the soil properties against the shaft wall. Many analyses take some of these variables into considerations and the same is true for the

PMT. Comprehensive design rules based on the PMT initial modulus Eo, Er, and the net limit pressure, Pl*, are available in the literature. These include methods to calculate axial capacity, defined as that load which generates 10% of shaft diameter in settlement, as well as linear and non-linear soil springs to calculate shaft movement under horizontal load. Of significance at the proposed location will be determining the effects of the slope which increases lateral movement when horizontally loaded normal to the slope. Large diameter shafts will feel the slope effect more than a group of driven piles connected by a pile cap. However, it is likely driving piles may be problematic at this site due to the very dense sands revealed by the site investigation, as well as the driving effects to the existing bridge which is in close proximity. For either driven piles or drilled shafts considerable capacity is available.

No details are available to InSitu Tech Inc of the final shaft diameter or embedment length.

However, Insitu Tech Inc was made aware that the preliminary likely drilled shaft option calls for a single

6 ft diameter and approximately 70 ft minimum embedment depth. The popular O’Neill and Reese drilled shaft procedures classify granular soil corrected blow counts above 50 to be called intermediate geo-materials (IGM). For corrected blow counts around the shaft tip of between 50 to 80 bpf, these procedures indicate tip capacity between 2000 kips to 3000 kips. For this size shaft embedded in the more uniform B7 location and by taking a constant PMT Pl* of 110 ksf for the full depth (Table 1) application of the PMT direct design rules given in Reference 1 show axial capacities of the order 5400 kips for the D/10 settlement criteria and shaft/tip ratio of 40/60. At the recommended 2.8 factor of safety for optimum design, suggested in Reference 1, a maximum axial working capacity of approximately 2000 kips is found. However, at this shaft diameter mobilizing the full working capacity is likely to generate excess settlement.

This shaft can also be analyzed for the serviceability limit state under horizontal loads where up to 5 mm (0.2 in) of shaft horizontal movement is considered linear under PMT methods. Again the more uniform B7 location is selected with initial and reload modulus values of 1800 ksf and 6000 ksf, respectively. With the PMT design rules showing horizontal pile subgrade modulus of 7800 ksf, the lateral load for this free head shaft movement is found to be of the order 700 kips. Beyond this load level, non-linear P-y methods are recommended which can also be established from the measured PMT data. The non-linear P-y method would also include the axial P- Δ effect which increases movement and bending moments.

Application of the PMT based pile capacity values for LRFD considerations, under French code, is also reported in the literature. For axial serviceability states these load levels are based on comparison to the, so called, creep load (Qc), beyond which significant curvature is expected in the load settlement relationship. For the 6 feet diameter and 70 feet long shafts analyzed for the White River Bridge this load is of the order 1650 tons.

Frictional resistance in most deep foundation design methods place limits on the maximum permissible side friction values from shallow depth reduction effects as well as other effects. The PMT method for the shaft considered here also has limits to frictional resistance. This caps the available net limit pressure (which is in excess of 100 ksf), used to calculate friction down the side of the shaft, to 30 ksf of the measured net limit pressure at B7 in these very dense sands. However, the higher sand stiffness, expressed by the PMT as Eo and Er, down the shaft significantly improve lateral performance.

The high Pl* available beneath the shaft toe raises the point capacity Qp as there is no limit placed on qu, only a limit placed on the PMT bearing factor, k.

InSitu Tech Inc would be happy to discuss any of these direct design rules further.

REFERENCES

1. The Pressuremeter by Jean-Louis Briaud, Balkema Press, 1987

APPENDIX 1 PRESSUREMETER CORRECTED CURVES

Test 3 in very dense (cemmented?)

med sand at 14.5 Ft in B10

2 4 6 8 10 Radial Expansion (%)

C av ity P re ss ur e

(k sf

Eo = 2228 ksf Er = 6635 ksf Pl* > 100 ksf

Test 4 in med dense sand at 22 FT in B 10

0 5 10 15 20 25 Radial Expansion (%)

R ad ia l E xp an si on

(k sf

Eo = 723 ksf Er = 3648 ksf Pl* = 68 ksf

Test 5 in v. dense sand at 31 FT in B10

5 7 9 11 13 15 17 19 Radial Expansion (%)

C av ity P re ss ur e

(k sf

Eo= 1248 ksf Er = 5342 ksf Pl* >90 ksf

Test 6 in v. dense Sand at 51.25 FT in B10

5 7 9 11 13 15 17 Radial Expansion (%)

C av ity P re ss ur e

(k sf

Eo= 2205 ksf Er = 4868 ksf Pl* = 95 ksf

Test 7 in v.dense sand at 72 FT in B10

7 9 11 13 15 17

Radial Expansion (%)

C av ity P re ss ur e

(k sf

Eo= 2987 ksf Er = 6041 ksf Pl* > 120 ksf

Test 8 in v. dense sand at 12 FT in B7

7 9 11 13 15 17 19 Radial Expansion (%)

C av ity P re ss ur e

(k sf

Eo = 2052 ksf Er = 8144 ksf Pl* >105 ksf

Test 9 in v. dense gravelly sand at 16 FT in B7

4 9 14 19 24 Radial Expansion (%)

C av ity P re ss ur e

(k sf

Eo = 1496 ksf Er = 4877 ksf Pl* >105 ksf

Test 10 in v. dense silty sand at 26.75 FT in B7

7 9 11 13 15 17 Radial Expansion (%)

C av ity P re ss ur e

(k sf

Eo = 2308 ksf Er = 7478 ksf Pl* >110 ksf

Test 11 in dense silty sand at 51.3 FT in B7

5 10 15 20 2 Radial Expansion (%)

C av ity P re ss ur e

(k sf

Eo= 1408 ksf Er = 4066 ksf

Pl* =80 ksf

Test 12 in silty v. dense sand at 72 FT in B7

5 10 15 20 Radial Expansion (%)

C av ity P re ss ur e

(k sf

Eo= 1934 ksf Er = 5170 ksf Pl* > 100 ksf