Liquefaction of a coal ash investigated by monotonic and cyclic triaxial tests

The critical state soil mechanics (CSSM) has been, recently, introduced as the major analytical framework for synthesising liquefaction behaviours of granular soils. However, liquefaction studies on coal ash have not been synthesised within the CSSM framework. Therefore, a series of monotonic and cyclic triaxial tests covering a range of initial states and testing conditions were conducted to evaluate static and cyclic liquefaction behaviours of coal ash. From the monotonic test results, a unique steady state line (SSL) was established for coal ash. Cyclic test results showed that cyclic liquefaction can be categorised into three distinct forms: cyclic instability, cyclic mobility and hybrid behaviour. Test results suggest that the occurrence of cyclic instability is related to static instability. Furthermore, the forms, if cyclic liquefaction occurred, were governed by the location of the initial state relative to the SSL.