Amir Vakili [email protected] P p-y p-y Pmcivil-strj.iau-maragheh.ac.ir/article_667461_d340980a548...sand Centrifuge 3*7 Square steel 42.9 3 Fixed 0.8 0.4 0.3 0.2 0.2 0.2 0.3 0.34 Rollins

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[email protected]

y-py-pmP

mP

mp

mp

P-Y

p-yp y

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][

p-y

mP

][p

- edge effect

mp

mp

mp

mp][

mP][

mp

- shadowing effect

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mp

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Abaqus

3D

Reported P -multiplier for row

Group reduction

factor 7 6 5 4 3 2 1 Pile head

conditionS/D D(cm)Pile typePile configurationTest typeSoil typeReference

0.6 0.5 0.6 0.7 Free 3 27.3Steel pipe 3*3 Full scale Stiff clay Brown et al (1987)[4] 0.53 0.4 0.5 0.7 Free 3 27.3 Steel pipe 3*3 Full scale Stiff clay

0.5 0.3 0.4 0.8 Free 3 27.3 Steel pipe 3*3Full scale Medium dense sand Brown et al (1987)[4]

0.85 0.7 0.85 1 Free 5 43 Steel pipe 3*3 Centrifuge Medium dense sand

Mc Yay et al (1995)[6] 0.85 0.7 0.85 1 Free 5 43 Steel pipe 3*3 Centrifuge Medium dense

sand

0.48 0.35 0.45 0.65 Free 3 43 Steel pipe 3*3 Centrifuge Medium dense sand

0.5 0.3 0.4 0.8 Free 3 43 Steel pipe 3*3 Centrifuge Medium dense sand

Mc Yay et al (1998)[7]

0.5 0.3 0.4 0.8 Fixed 3 42.9 Square steel3*3 Centrifuge sand0.45 0.3 0.3 0.4 0.8 Fixed 3 42.9 Square steel3*3 Centrifuge sand0.4 0.3 0.2 0.3 0.4 0.8 Fixed 3 42.9 Square steel3*5 Centrifuge sand

0.37 0.3 0.2 0.2 0.3 0.4 0.8 Fixed 3 42.9 Square steel3*6 Centrifuge sand0.34 0.3 0.2 0.2 0.2 0.3 0.4 0.8 Fixed 3 42.9 Square steel3*7 Centrifuge sand0.47 0.43 0.38 0.6 Free 3 40 Steel pipe 3*3 Full scale Clay and silt Rollins et al (1998)[9] 0.69 0.66 0.61 0.61 0.89 Fixed 3 80 Precast RC 3*4 Full scale

0.47 0.43 0.38 0.6 Fixed 3 32.4 Steel pipe 3*3 Full scale Silty and clay Rollins and Sparks(2002)[8]

0.53 0.4 0.4 0.8 Free 3.3 32.4 Steel pipe 3*3 Full scale Sand Rollins et al (2005)[10]

0.62 0.45 0.61 0.82 Free 3 61 Steel pipe 3*5 Full scale Stiff clayRollins et al (2005)[10] 0.87 0.77 0.88 0.95 Free 5.65 32.4 Steel pipe 3*3 Full scale Stiff cl ay

0.78 0.73 0.69 0.8 0.9 Free 4.4 32.4 Steel pipe 3*4 Full scale Stiff clay 0.57 0.51 0.45 0.45 0.61 0.82 Free 3.3 32.4 Steel pipe 3*5 Full scale Stiff clay

p

( )

][2T

][

Length(cm) Spacing/ DiameterDiameter(cm)

Load Cell

ASTM D 421-87

ASTM D 2167-84

ASTM D 698-78

ASTM D 3080-90][

Comments ASTM Standard Quantity Parameters

Picnometer Test

Direct Shear Test

Dry Pour Test

Dynamic Cyclic Loading

In-situ Density

cm

=3.5

][

0.1D][

y-pmp

mp

mp

mP

6P5P4P3P2P1P0.540.380.462×11.50.40 0.620.460.542×12.50.400.870.740.812×13.50.40

0.590.330.240.393×11.50.400.710.500.370.523×12.50.400.930.690.530.713×13.50.40

0.410.410.200.200.312×21.50.400.590.590.370.370.482×22.50.400.740.740.590.590.662×23.50.40

0.450.450.250.250.180.180.293×21.50.400.570.570.420.420.270.270.423×22.50.400.800.800.580.580.440.440.603×23.50.40

mp

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[1]. API, Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms, 15th ed., API RP2A, American Petroleum Institute, 1958, pp115.

[2]. API, Recommended practice for planning, designing, and constructing fixed offshore platform s, API Recommended Practice 2A -WSD, 21st ed. American petroleum Institute, Washington, D. C, 2007.

[3]. Elhakim, A., Elkhouly, M. and Awad, R., Three dimensional modeling of laterally loaded pile groups resting in sand. HBRC journal, 12(1), 2016, pp 78 -87.

[4]. Brown, Dan A., Clark Morrison, and Lymon C. Reese. Lateral load behavior of pile group in sand. Journal of Geotechnical Engineering 114 (11), 1988, pp. 1261-1276.

[5]. Brown, Dan A., et al. Static and dynamic lateral loading of pile groups. Washingt on, DC, USA: TRB, 2001.

[6]. McVay, M., Casper, R. and Shang, T.I. Lateral response of three-row groups in loose to dense sands at 3D and 5D pile spacing. Journal of Geotechnical Engineering, 121(5), 1995, pp 436-441.

[7]. McVay, M., Zhang, L., Molnit, T., and Lai, P., Centrifuge testing of large laterally loaded Pile groups in sands, Journal of Geotechnical and Geoenvironmental Engineering, 124(10), 1998, pp 1016-1026.

[8]. Rollins, Kyle M., and Andrew Sparks. Late ral resistance of full -scale pile cap with gravel backfill. Journal of Geotechnical and Geo environmental Engineering 128(9), 2002, pp 711-723.

[9]. Rollins, K.M., Peterson, K.T., and Weaver, T.J., Lateral load behavior of full -scale pile group in clay,

Journal of Geotechnical and Geo environmental Engineering,124(6), 1998, pp 468-478.

[10]. Rollins, K.M., Lane, J.D., and Gerber, T.M., Measured and computed lateral response of a pile group in sand, Journal of Geotechnical and Geo

environmental Engineering ,131(1), 2005, pp 103-114.

][

][

][

[14]. Bharathi, M., R. N. Dubey, and Sanjay K. Shukla. Experimental investigation of vertical and batter pile groups subjected to dynamic loads. Soil Dynamics and Earthquake Engineering, 116, 2019, pp 107-119.

[15]. Terzaghi, K., Evolution of coefficients of subgrade reaction. Geo technique, 5(4), 1995, pp 297-326.

[16]. Broms, Bengt B. Lateral resistance of piles in cohesionless soils. Journal of the Soil Mechanics and Foundations Division 90(3), 1964, pp 123-158.

[17] ASTM D-4253 & 4254, Annual book of ASTM standards, Baltimore, USA. 2002.

[18]. Wakai, A., Gose, S., and Ugai, K. 3 -D elasto-plastic finite element analysis of pile foundations

subjected to lateral loading, Soil and Foundation, Tokyo, 39(1), 1999, pp 97-111.

[19]. Ovesen, N.K., The use of physical models in design: The scaling law relationship, Proc., 7 th European Conf. on Soil Mechanics and Foundation Engineering,4, 1979, pp 318-323.

Laboratory Investigation of the Pile Group Behavior in Sandy Soils under Lateral Loads

Amir Vakili

Department of Civil Engineering, Beyza Branch, Islamic Azad University, Beyza, Iran Mohammad Ali Zomorodian

Department of Civil Engineering, Shiraz University, Shiraz, Iran Mohammad Hossein Ahmadi

Department of Civil Engineering, Beyza Branch, Islamic Azad University, Beyza, Iran

Abstract Structures are often subjected to lateral loads due to earthquakes, winds, and waves of water. It is very necessary to predict and measure the "load -deflection" behavior of the pile group, as well as its strain behavior, in order to create a safe and economical design. The behavior of piles embedded in soil, placed under the lateral load, is typically modeled and analyzed using the Winkler nonlinear springs method. In this method, the soil-pile interaction is modeled by nonlinear curves of P-Y in a way that P-Y curve modifies and adjust the single pile using a p-multiplier ( ) for each row of piles in the group. The factor depends upon the configuration of pile group and the pile spacing. The value of this factor for the leading rows are considered higher and for the trailing rows lower. The present study was conducted to investigate the effects of various parameters, such as the pile spacing in the group and different layouts on the factor. The factor obtained from this study has good compatibility with the results of the full-scale test on pile group. The results show that the value of the factor for pile groups with different layouts of 2.5-diameter pile spacing was in the range of 0.42 to 0.54, which is very close to the value of obtained by previous study. Key words: Pile group, Lateral load, P-Y method, Group reduction factor