Cranfield University

Ancillary Experiments
contact area. � h is restrained by the passive earth pressure � p and depending on which is
larger the soil moves or moves not sideways.
For the sandy loam soil of the soil bin cohesion c is 5 kN/m 2 and the angle of internal fric-
tion � is 39 degree (Ansorge, 2005, a). � h is calculated with the following equation:
� �
h � k0 � v
whereby k0 equals:
k
0
� 1�
sin�
from the above equation follows k0 = 0.37.
Eq. 14
Eq. 15
Taking a load of G = 105 kN on a contact area A = 0.94 m 2 and assuming that the soil has a
density of 14kN/m 3 and assuming a depth z = 0.4 m results for � v from the following
equation which takes the surcharge and the additional tyre load into account:
G
� v � � � � z
A
� v = 117.3 kN/m 2
Eq. 16
putting � v in Eq. 14 results in the horizontal pressure component� h = 43.4 kN/m 2 . This is
the force pushing the soil sideways. The force which restrains this movement is the passive
earth pressure equation of Rankine (1943) Theory which results for � p in:
tan ( 45 ) 2 tan( 45 )
2
2
2 �
�
� p � � � z � � � � c � �
with the given numbers from above � p = 45.6 kN/m 2
Eq. 17
As � p > � h the soil can not move sideways. For the softer soil condition used by Antille
(2006) whereby sideways movement was detected for a DBD of 1.2 g/cm 3 and cohesion of
4kN/m 2 , the resulting � p is equal to 37.9 kN/m 2 whereby � h was marginally smaller with
43.2 kN/m 2 and consequently the soil can move sideways. Quod erat demonstrandum.
Ph.D. Thesis Dirk Ansorge (2007)
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