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International Conference on Case Histories in (2004) - Fifth International Conference on Case Geotechnical Engineering Histories in Geotechnical Engineering

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Performance of a Highway Embankment Constructed over Landfill Material

Paul J. Lewis Gannett Fleming, Inc., Camp Hill, Pennsylvania

Jack Mansfield Department of Transportation, Trenton, New Jersey

Syed Ashraf Gannett Fleming, Inc., South Plainfield, New Jersey

Kessi Zicko Gannett Fleming, Inc., Camp Hill, Pennsylvania

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Recommended Citation Lewis, Paul J.; Mansfield, Jack; Ashraf, Syed; and Zicko, Kessi, "Performance of a Highway Embankment Constructed over Landfill Material" (2004). International Conference on Case Histories in Geotechnical Engineering. 30. https://scholarsmine.mst.edu/icchge/5icchge/session02/30

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PERFORMANCE OF A HIGHWAY EMBANKMENT CONSTRUCTED OVER LANDFILL MATERIAL

Paul J. Lewis, P.E. Jack Mansfield, P.E. Syed Ashraf, P.E. Kessi Zicko, E.I.T. Gannett Fleming, Inc. New Jersey Dept. of Transportation Gannett Fleming, Inc. Gannett Fleming, Inc. Camp Hill, Pennsylvania - Trenton, New Jersey - South Plainfield, New Jersey - Camp Hill, Pennsylvania - USA-17011 USA-08625 USA-07080 USA-17011

ABSTRACT

This paper presents settlement data over a period of 12 years for two portions of a highway embankment constructed over landfill material. Construction was completed in 1989 and included dynamic compaction to limit post construction settlement. A preload / surcharge was used over a separate portion of one of the highway embankments as an alternative foundation improvement technique for the purpose of comparison and evaluation of the effectiveness of the two methods. Elevation measurements taken over a period of 12 years are presented for comparison of post construction settlement of both dynamically compacted and surcharged sections of the highway embankments.

INTRODUCTION SITE CONDITIONS

The of New Jersey Route 18 with the Garden The project grades and alignment required construction of State was constructed in 1988. The alignments of the highway embankments ranging from 3 to 9 meters in height mainline roadways and connector ramps associated with this over the landfill. The landfill material generally consists of interchange traverse the former Tinton Falls Landfill. This domestic sanitary refuse with occasional deposits of organic municipal landfill ceased operation in the early 1970’s. refuse (yard waste) and construction debris. In general, the Dynamic compaction was used to densify the landfill prior to landfill material was estimated to consist of approximately constructing the highway embankments in order to limit post- 45 percent organic material. The typical depth of the landfill construction settlement. For comparison to dynamic material varied from about 1.8 to 7.4 meters. The landfill is compaction, a preload / surcharge embankment was used over underlain by coastal plain deposits consisting primarily of a portion of one embankment as an alternative soil medium dense to dense silty sand. Groundwater is located at improvement technique. Elevation measurements taken over a the bottom of the landfill. period of twelve years following completion of construction provide a comparison of the effectiveness of the two ground improvement techniques. The purpose of this paper is to DYNAMIC COMPACTION present the elevation data collected over the twelve years following completion of construction and provide an Dynamic compaction completed on this site consisted of high- evaluation of the effectiveness of dynamic compaction versus energy drops with an 18,160-kilogram weight dropped from a surcharging / preloading in limiting long term settlement of a height of 24.4 meters. Two solid steel weights with different highway embankment constructed over a municipal landfill. cross sections were used for high-energy drops. One consisted An evaluation and comparison of the monitored secondary of a 1.8-meter square weight while the other consisted of a compression settlements are presented. A brief description of 2.1-meter diameter circular weight. The weight was dropped the project site conditions, dynamic compaction process and five to ten times at each location until maximum compaction surcharge / preload construction are presented herein. A more was achieved as evidenced by no increase in crater depth. detailed description of the project can be found in Lewis and Dynamic compaction was completed on a square grid pattern Langer [1994]. A plan view of the project site showing the with a final grid spacing of 3.8 meters center to center. monitoring sections and the approximate limits of the landfill Craters produced from high-energy impacts were backfilled is presented in Fig. 1. with granular material which was subsequently compacted with a low-energy ironing pass performed with an 18,160-kilogram weight dropped from a height of 12.2 meters.

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Fig.1 Plan view of the project site showing the station limits of dynamic compaction and preload / surcharge ground improvements.

The low-energy weight consisted of a 5.8-meter square weight the periodic survey elevation data to the as-built roadway constructed of solid steel. The ironing pass utilized an elevations allows for the computation of settlement with time. overlapping grid pattern. Tables 1 and 2 present the embankment height, landfill thickness, and total settlement observed over the monitoring period at each location monitored for the roadway SURCHARGE / PRELOAD embankment underlain by landfill treated by dynamic compaction and preload / surcharge, respectively. A portion of one of the interchange ramps (Ramp E) was selected to receive a preload / surcharge in lieu of dynamic compaction. A 1.5-meters high surcharge was constructed EVALUATION OF LONG TERM PERFORMANCE over the final profile grade and the embankment was monitored for a period of 6 months. At the end of the 6-month Analysis of the data presented in Tables 1and 2 indicates that preload period, the surcharge was removed and final roadway the total settlement observed over the monitoring period for construction was completed. the embankment underlain by landfill treated by dynamic compaction ranges from approximately 85 to 215 mm. Total settlement observed for the same period for the embankment MONITORING underlain by landfill treated by preload / surcharge ranges from approximately 282 to 651 mm. Tables 3 and 4 present Following completion of construction, portions of the roadway the ratio of total settlement in mm to landfill thickness in embankment were monitored by periodic elevation surveys. meters in order to compare the total settlement based on an Elevation measurements were collected along Route 18 SW at equivalent thickness of landfill material. From Table 3, the 100-foot intervals from station 1394+00 to station 1399+00 observed settlement for the area treated by dynamic where the underlying landfill material was compacted by the compaction ranged from 24.3 to 48.3 and averaged 36.9 mm dynamic compaction process. Elevation measurements were of settlement per meter of landfill thickness over the 12-year also collected along Ramp E at 100-foot intervals from station monitoring period. In comparison, from Table 4, the observed 13+00 to station 19+00 where the underlying landfill material settlement for the area treated by preload / surcharge ranged was treated by preloading / surcharging. Survey elevation from 47.8 to 89.2 and averaged 72.4 mm of settlement per data were collected over a period of twelve years. Comparing meter of landfill thickness over the 12-year monitoring period.

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Table 1. Dynamic Compaction Summary

Embankment Landfill Settlement Height Thickness (mm) Station (m) (m) Sep-91 Jul-93 Apr-95 Sep-97 Feb-00 Mar-03

1394+00 8.3 2.3 46 40 48 66 51 114 1395+00 7.7 1.8 9 24 17 36 25 87 1396+00 5.4 3.5 30 1 23 13 85 1397+00 4.5 4.6 58 79 62 85 77 149 1398+00 3.0 6.7 24 58 75 116 126 215 1399+00 3.3 6.5 33 55 62 93 Note: Construction of embankment completed in 1989.

Table 2. Preload / Surcharge Summary

Embankment Landfill Settlement Height Thickness (mm) Station (m) (m) Sep-91 Jul-93 Apr-95 Sep-97 Feb-00 Mar-03

13+00 7.5 6.2 55 43 179 228 261 375 14+00 6.7 6.3 186 213 321 378 414 536 15+00 5.2 7.1 167 183 325 397 441 564 16+00 4.0 7.4 217 241 387 464 508 636 17+00 3.2 7.3 147 180 308 426 497 651 18+00 2.7 6.6 25 34 147 214 256 389 19+00 2.3 5.9 18 100 144 168 282 Note: Construction of embankment completed in 1989.

Table 3. Ratio of Total Settlement to Landfill Thickness for Table 4. Ratio of Total Settlement to Landfill Thickness for Dynamic Compaction Area Preload / Surcharge Area

Ratio of Total Ratio of Total Settlement to Settlement to Landfill Total Landfill Landfill Total Landfill Thickness Settlement Thickness Thickness Settlement Thickness Station (m) (mm) (mm/m) Station (m) (mm) (mm/m)

1394+00 2.3 114 49.6 13+00 6.2 375 60.5 1395+00 1.8 87 48.3 14+00 6.3 536 85.1 1396+00 3.5 85 24.3 15+00 7.1 564 79.4 1397+00 4.6 149 32.4 16+00 7.4 636 85.9 1398+00 6.7 215 32.1 17+00 7.3 651 89.2 1399+00 6.5 - - 18+00 6.6 389 58.9 Range = 24.3 to 49.6 mm/m 19+00 5.9 282 47.8 Average = 37.3 mm/m Range = 47.8 to 89.2 mm/m Average = 72.4 mm/m

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Figure 2 presents a settlement profile vs. time for the the roadway embankment constructed over landfill material embankment underlain by landfill treated by dynamic treated by dynamic compaction is performing well with compaction while Fig. 3 presents a settlement profile vs. time respect to observed settlement over the 12-year monitoring for the embankment underlain by landfill and treated by period as compared to the roadway embankment constructed preload / surcharge. Review of Figures 2 and 3 indicate that over landfill material treated by preload / surcharge.

-800 16

-600 12

-400 8

Embankment )

m 1989 (

) Height

s

m Landfill -200 4 s 1991 e m n ( Thickness

k 1993 t 1989 c n i e 0 0 h 1995 T m

e l l a

t 1997 i t r e e S 200 -4 t 2000 a

2003 M 2003 400 -8

600 -12

800 -16 1393 1394 1395 1396 1397 1398 1399 1400 Station (+00)

Fig. 2. Settlement profile along portion of mainline embankment subjected to dynamic compaction.

-800 16

-600 12 Embankment Height -400 8 )

m 1989 ( ) Landfill s

m -200 4 s 1991

Thickness e m n (

1989 k 1993 t c n i e 0 0 h 1995 T m

e l l

a 1997 t i t r e e S 200 -4 t 2000 a

M 2003 400 -8 2003 600 -12

800 -16 12 13 14 15 16 17 18 19 20 Station (+00)

Fig. 3. Settlement profile along portion of Ramp E embankment subjected to preload / surcharge.

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Secondary settlement in the dynamic compaction area is data collected for each monitoring point. The following progressing at a much slower rate and differential settlement is equation from Bowles [1984] was used to perform the back not as extreme as that observed in the preload / surcharge area. calculation assuming that primary compression was complete Figures 4 and 5 present photographic representation of the in 1991: roadway performance for each of the sections monitored. C = / Log (t /t ) (1) α ∆ε 2 1

Tables 5 and 6 present the computed coefficient of secondary compression for each monitoring location. Review of Table 5 indicates that Cα ranges from 0.0153 to 0.0513 with an average value of 0.0313 for the landfill material treated by dynamic compaction. Review of Table 6 indicates that Cα ranges from 0.0529 to 0.0817 with an average value of 0.0657 for the landfill material treated by preload / surcharge.

NAVFAC [1982] indicates that the coefficient of secondary compression for landfills which have experienced decomposition for 10 to 15 years prior to new loading ranges from 0.02 to 0.07. For the landfill materials subjected to dynamic compaction, the Cα values are generally in the lower portion of this range. The Cα values for the landfill materials that underwent the preload / surcharge soil improvement are in the upper portion of the range.

Fig. 4. Minimal deformation of the roadway occurred due to settlement at the Dynamic Compaction location. CONCLUSION

Review of settlement data collected over a period of 12 years after construction of a highway embankment built over landfill material treated using two different ground modification techniques indicates that dynamic compaction is more effective in reducing the rate of secondary compression than preload / surcharging. The settlement observed over the 12-year period per meter of landfill thickness is approximately double in the preload / surcharge area as compared to the area treated by dynamic compaction. Furthermore, back calculation of the coefficient of secondary compression indicates that this parameter was effectively reduced by up to 50 percent for landfill material treated by dynamic compaction as compared to landfill material treated by preload / surcharging.

REFERENCES

Bowles, J.E. [1984]. “Physical and Geotechnical Properties Fig. 5. Significant deformation of the roadway was caused by of Soils”, McGraw-Hill Book Company, New York, NY. settlement at the Ramp E Preload / Surcharge location.

Lewis, P.J. and J.A. Langer [1994]. “Dynamic Compaction of

Landfill Beneath Embankment”, ASCE Geotechnical Special Figure 6 presents total settlement vs. time for all monitored Publication No. 40: Vertical and Horizontal Deformations of locations for both the dynamic compaction and preload / Foundations and Embankments, pp. 451-461. surcharge treatment areas. As shown in this figure, dynamic compaction was more effective in reducing the rate of U.S. Department of the Navy [1983]. “Soil Dynamics, Deep secondary settlement as compared to the preload / surcharge Stabilization, and Special Geotechnical Construction”, Design treated area. In order to compare and quantify the reduction in Manual 7.3, NAVFAC DM7.3, Naval Facilities Engineering the rate of secondary settlement, the coefficient of secondary Command, Alexandria, VA. compression (Cα) was computed from total settlement vs. time

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0

100 13+00 14+00 200 15+00 16+00 )

m 300 17+00 m (

18+00 t n

e 400 19+00 m e l 1394+00 t t e

S 500 1395+00 1396+00 600 1397+00 Solid Lines - Preload / Surcharge 1398+00 Dashed Lines - Dynamic Compaction 700 1399+00

800 1988 1990 1992 1994 1996 1998 2000 2002 2004 Year

Fig. 6. Comparison of the amount settlement of embankments at the Dynamic Compaction and Preload / Surcharge locations.

Table 5. Coefficient of Secondary Compression (Cα) of Landfill Material at the Dynamic Compaction Area

Landfill Thickness Settlement (mm) Station (m) Sep-91 Mar-03 Cα

1394+00 2.3 46 114 0.0350 1395+00 1.8 9 87 0.0513 1396+00 3.5 30(a) 85 0.0289 1397+00 4.6 58 149 0.0234 1398+00 6.7 24 215 0.0337 1399+00 6.5 33 93(b) 0.0153 (a) Jul-93 data point Range = 0.0153 to 0.0513 (b) Sep-97 data point Average = 0.0313

Table 6. Coefficient of Secondary Compression (Cα) of Landfill Material at the Preload / Surcharge Area

Landfill Thickness Settlement (mm) Station (m) Sep-91 Mar-03 Cα

13+00 6.2 55 375 0.0611 14+00 6.3 186 536 0.0657 15+00 7.1 167 564 0.0662 16+00 7.4 217 636 0.0670 17+00 7.3 147 651 0.0817 18+00 6.6 25 389 0.0653 19+00 5.9 18 282 0.0529 Range = 0.0529 to 0.0817 Average = 0.0657

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