Lateral Load Capacity and Passive Resistance of Full-Scale Pile Group and Cap

Abstract

Static and dynamic (statnamic) lateral load tests were performed on a full-scale 3 × 3 pile group driven in saturated low-plasticity silts and clays. The 324-mm outside diameter steel pipe piles were attached to a reinforced concrete pile cap (2.74 m square in plan and 1.21 m high), which created an essentially fixed-head end constraint. A gravel backfill was compacted in place on the back side of the cap. Lateral resistance was therefore provided by pile-soil-pile interaction as well as by base friction and passive pressure on the cap. In this case, passive resistance contributed about 40 percent of the measured static capacity. The measured resistance was compared with that computed by several techniques. The log-spiral method provided the best agreement with measured resistance. Estimates of passive pressure computed using the Rankine or GROUP p-y curve methods significantly underestimated the resistance, whereas the Coulomb method overestimated resistance. The wall movement required to fully mobilize passive resistance in the dense gravel backfill was approximately 0.06 times the wall height, which is in good agreement with design recommendations. The p-multipliers developed for the free-head pile group provided reasonable estimates of the pile-soil-pile resistance for the fixed-head pile group. Default p-multipliers in the program GROUP led to a 35 percent overestimate of pile capacity. Overall dynamic resistance was typically 100 to 125 percent higher than static; however, dynamic passive pressure resistance was over 200 percent higher than static.

Get full access to this article

View all access options for this article.

References

Brown

D. A.

, Reese

L. C.

, and O’Neill

M. W.

. Behavior of a Large Scale Pile Group Subjected to Cyclic Lateral Loading. Journal of Geotechnical Engineering, ASCE, Vol. 113, No. 11, 1987, pp. 1326–1343.

Rollins

K. M.

, Peterson

K. T.

, and Weaver

T. J.

. Lateral Load Behavior of a Full-Scale Pile Group in Clay. Journal of Geotechnical and Geoenvironmental Engineering, Vol. 124, No. 6, 1998, pp. 468–478.

Peterson

K. T.

, and Rollins

K. M.

. Static and Dynamic Lateral Load Testing of a Full-Scale Pile Group in Clay. Research Report CEG.96-02. Civil Engineering Department, Brigham Young University, Provo, Utah, 1996, 223 pp.

Rollins

K. M.

, Clayton

R. J.

, Mikesell

R. C.

, and Blaise

B. C.

. Drilled Shaft Side Friction in Gravelly Soils. Report No. UT-97.02. Utah Department of Transportation, 1997, 180 pp.

Matlock

, and Reese

L. C.

. Generalized Solutions for Laterally Loaded Piles. Journal of Soil Mechanics and Foundations Division, ASCE, Vol. 86, SM5, 1960, pp. 63–91.

Reese

L. C.

, Wang

S. T.

, Arrellaga

J. A.

, and Hendrix

. Computer Program GROUP for Windows, User’s Manual, Version 4.0. Ensoft, Inc., Austin, Tex., 1996, 370 pp.

Reese

L. C.

, Cox

W. R.

, and Koop

F. D.

. Analysis of Laterally Loaded Piles in Sand. In Proc., Fifth Annual Offshore Technology Conference, Paper No. OTC 2080, Houston, Tex., 1974.

Matlock

Correlations for Design of Laterally-Loaded Piles in Soft Clay. In Proc., Second Annual Offshore Technology Conference, Paper No. OTC 1204, 1970, Vol. 1, pp. 577–594.

Caquot

, and Kerisel

. Active and Passive Earth Pressure Tables. Balkema, Rotterdam, Netherlands, 1948.

10.

Memo to Designers 5-1. Division of Structures, California Department of Transportation, Sacramento, Sept. 1988.

11.

Ovesen

N. K.

, and Stromann

. Design Methods for Vertical Anchor Slabs in Sand. In Proc., Specialty Conference on Performance of Earth and Earth-Supported Structures, ASCE, New York, 1972, Vol. 2.1, pp. 1481–1500.

12.

Potyondy

J. G.

Skin Friction Between Various Soils and Construction Materials. Geotechnique, Vol. 11, No. 4, 1961, pp. 339–363.

13.

Carder

D. R.

, Pockock

R. G.

, and Murray

R. T.

. Experimental Retaining Wall Facility: Lateral Stress Measurements with Sand Backfill. Report 7565. U.K. Transport and Road Research Laboratory, Crowthorne, Berkshire, England, 1977, 18 pp.

14.

Narain

R. J.

, Saran

, and Nandakumaran

. Model Study of Passive Pressure in Sand. Journal of Soil Mechanics and Foundations Division, ASCE, Vol. 95, SM4, 1969, pp. 969–983.

15.

Foundations and Earth Structures, Design Manual 7.2. Naval Facilities Engineering Command, U.S. Department of the Navy, Alexandria, Va., 1982, pp. 7.2–60.

16.

Tschebotarioff

G. P.

, and Johnson

E. G.

. The Effects of Restraining Boundaries on the Passive Resistance of Sand. Office of Naval Research Report. Department of Civil Engineering, Princeton University, Princeton, N.J., 1953.

17.

Rollins

K. M.

, and Peterson

K. T.

. Lateral Statnamic Load Testing and Analysis of a Pile Group. In Proc., Specialty Conference on Geotechnical Earthquake Engineering and Soil Dynamics, ASCE Geo-Institute, 1998, Vol. 2, pp. 1319–1330.