Lateral Earth Pressure

Lateral earth pressure is the pressure exerted by a fill material on the wall of a structure like a retaining wall.  Lateral earth pressure is represented by the coefficient of lateral earth pressure at rest, KO, which is horizontal stress divided by vertical stress.  Poisson's ratio, μ, relates horizontal deformation to vertical deformation.  Table 1 lists values for the coefficient of lateral earth pressure and Poisson's ratio.

Table 1. Summary of coefficient of lateral earth pressure at rest and Poisson's ratio

Particle size range (in.)	Tire shred type	Source of tire shreds	Ko	μ	Reference
2	Mixed	Sawyer Environmental	0.44	0.30	(1)
3	Mixed	Palmer Shredding	0.26	0.20	(2)
2	Mixed	Pine State Recycling	0.41	0.28	(2)
1	Glass	F & B Enterprises	0.47	0.32	(2)
----	----	----	----	0.3 to 0.17	(3)
2	Mixed	Maust Tire Recycles	0.4a	0.3	(4)

Notes:  a.  For vertical stress less than 25 psi.

 References:

            (1)  Manion and Humphrey (1992); Humphrey and Manion (1992)
            (2)  Humphrey, et al. (1992, 1993); Humphrey and Sandford (1993)
            (3)  Edil and Bosscher (1992, 1994)
            (4)  Drescher and Newcomb (1994)

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