DESIGN OF CANTILEVER TYPE SHEET PILE PENETRATING SAND

Enter the value of the angle of shearing resistance of sand (f) degrees

Enter the value of the dry unit weight of sand (gd) kN/m3

Enter the value of the saturated unit weight of sand (gsat) kN/m3

Enter the sheet pile depth to sea level (L1) m

Enter the sheet pile depth from sea level to dredge line (L2) m

the value of the effective unit weight of sand gsub = gsat - (gw = 9.81 kN/m3) = kN/m3

coefficient of active earth pressure (Ka) = (1 - sin f) / (1 + sin f) =

coefficient of passive earth pressure (Kp) = (1 + sin f) / (1 - sin f) =

pressure P1 = gd L1 Ka = kPa

pressure P2 = (gd L1 + gsub L2) Ka = kPa

distance L3 = P2 / [gsub (Kp - Ka)] = m

force F1 = P1 L1 / 2 = kN/m

force F2 = P1 L2 = kN/m

force F3 = (P2 - P1) L2 / 2 = kN/m

force F4 = P2 L3 / 2 = kN/m

force F = F1 + F2 + F3 + F4 = kN/m

distance d = [F1 (L1 / 3 + L2 + L3) + F2 (L2 / 2 + L3) + F3 (L2 / 3 + L3) + F4 (2 L3 / 3)] / F = m

pressure P5 = (gd L1 + gsub L2) Kp + gsub L3 (Kp - Ka) = kPa

coefficient A1 = P5 / [gsub (Kp - Ka)] =

coefficient A2 = 8 F / [gsub (Kp - Ka)] =

coefficient A3 = 6 F [2 d gsub (Kp - Ka) + P5] / [(gsub)2 (Kp - Ka)2] =

coefficient A4 = F (6 d P5 + 4 F) / [(gsub)2 (Kp - Ka)2] =

To find the length L4, the following equation must satisfy

(L4)4 + A1 (L4)3 - A2 (L4)2 - A3 L4 - A4 = 0

Enter a trial value for the length L4 m

the right hand side (RHS) of the above L4 equation , if different from zero, assume a new trial value for L4, enter in the box in the previous step and calculate RHS again. Repeat these steps until RHS matches zero.

the theoretical depth of sheet pile D = L3 + L4 = m

the actual depth of sheet pile Dact = 1.3 D = m

the total height of sheet pile L1 + L2 + Dact = m

Calculation of maximum moment and section modulus

distance of plane of zero shear Z' = [2 F / gsub (Kp - Ka)]1/2 = m

maximum moment Mmax = F (d + Z') - [gsub (Kp - Ka) / 6] (Z')3 = kN.m

Steel

Type

 Allowable Stress

(sall) MN/m2
ASTM A-328 170
ASTM A-572 210
ASTM A-690 210

Enter, from Table above, the allowable flexural stress of the sheet pile material sall = MN/m2

section modulus of sheet pile S = Mmax / sall = m3/m of wall

Summary of Design

Angle of shearing resistance of sand (f) degrees

Dry unit weight of sand (gd) kN/m3

Saturated unit weight of sand (gsat) kN/m3

Depth to sea level (L1) m

Depth from sea level to dredge line (L2) m

Theoretical depth of sheet pile D = m

Actual depth of sheet pile Dact = m

Total height of sheet pile L1 + L2 + Dact = m

Maximum moment Mmax = kN.m

Allowable flexural stress of the sheet pile material sall = MN/m2

Section modulus of sheet pile S = m3/m of wall

Copyright 2007-2024 A. Ghaly. All rights reserved. Contact A. Ghaly at ghalya@union.edu

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Disclaimer: The author disclaims any and all responsibility for the application of stated principles, and shall not be liable for any loss or damage arising therefrom.