Damage on the stress-strain behaviour of cement-mixed gravel by unloading

Abstract

Compacted cement-mixed gravelly soil (CMG) is now often used to 5 construct important structures requiring a high stability allowing a very limited amount of deformation. CMG may be subjected to various loading histories, including cyclic loading prior to loading during service. For example, cyclic loading in the vertical direction takes place by traffic loads and randomly during seismic events, which may affect the stress-strain behaviour. The pre-peak stress –strain behaviour of sedimentary soft rock is not as reversible as hard rock and prone to various effects of pre-shearing. It may be seen from Fig. 1 that pre-shearing history significantly changed the pre-peak stress-strain relations in a drained triaxial compression (TC) test at a constant effective confining pressure on a saturated core sample of sedimentary soft rock. The stress-strain relation during reloading becomes softer with an increase in the negative axial strain increment during the immediately precedent unloading branch. This trend is opposite to the one usually observed with ordinary unbound granular materials subjected to cyclic loading and due likely to effects of damage to bonding. This issue with CMG was studied by drained TC tests.