An Investigation into Support Interaction of Ground Support Through Numerical Modelling and Laboratory Testing

Tunneling within soil and weaker rock oftentimes utilizes temporary support elements. Over the years, developments have included specialized pre-manufactured support, mechanized installation systems, new techniques and new grout materials. Other advances, to the design process specifically, have been the improvement of computer modelling software that allow for predictions of tunnel behaviour and support behaviour. Despite these advances, there is currently limited knowledge on the mechanisms involved with how, specifically, the surface of the support element interacts with the ground and with the adhesive medium (e.g. grout) which often acts as the internal fixture in the support system. There also exists limited database in technical literature of interface parameters for the support system materials (i.e. grout–ground, grout–support element, support element–ground). These interaction parameters are fundamental to better inform design decisions and help to improve the numerical models used to predict excavation mechanical behaviour. In this way, this paper presents an attempt to identify, via numerical modelling, the most sensitive mechanical interaction parameters at the interfaces of ground support system materials as well as quantify their value through pull-out and shear laboratory tests. The mechanical behaviour of the support materials interface is also investigated.