Performance assessment of timber support system subjected to combined actions

Timber chocks are commonly used in underground operations as the standing support system to stabilise the excavations. They are constructed by stacking notched hardwood components into interlocking structures, and depending on various factors such as level of stress redistribution, ground movement, and roof or floor convergence, they could be subjected to different actions including combined vertical and horizontal. This study, for the first time, examines the mechanical performance of timber chock under combined actions, being (1) axial service load followed by ultimate axial displacement to failure; (2) axial service load followed by ultimate lateral displacement to failure and (3) axial service load followed by a combination of ultimate axial and lateral displacements simultaneously to failure. Nine timber chock specimens are tested using the Multi-Axis Substructure Testing (MAST) system followed by an extensive experimental analysis. These include the performance of specimens from the elastic range through to collapse along with the damage progression analysis, offering critical insights into the load carrying capacity, damage initiation and failure mechanisms of timber chock under complex loading conditions envisaged in the underground mining environments. • Characterising the mechanical behaviour of timber support system under axial, lateral and combined actions. • Assessing the damage progression and failure mechanisms of timber support system under complex loading conditions. • Development of a design protocol to enhance the performance and safety of timber support system in service.