Table 3 Passive earth pressure coefficients for ϕ = 20° with various angles of sloping backfill (negative wall friction).

From: Passive earth pressure on vertical rigid walls with negative wall friction coupling statically admissible stress field and soft computing

ϕ = 20°

β (degree)

δ (degree)

− 20

− 15

− 10

− 5

0

5

10

15

20

− 0

0.771

1.225

1.517

1.787

2.031

2.302

2.505

2.765

2.964

− 5

0.727

1.114

1.364

1.567

1.765

1.983

2.166

2.336

2.463

− 10

0.677

0.973

1.199

1.368

1.509

1.644

1.807

1.915

2.017

− 15

0.620

0.869

1.019

1.135

1.258

1.330

1.410

1.488

1.566

− 20

0.549

0.713

0.787

0.835

0.866

0.872

0.888

0.876

0.883